WorldWideScience

Sample records for bearing thymine 5-methylcytosine

  1. The use of permanganate as a sequencing reagent for identification of 5-methylcytosine residues in DNA.

    OpenAIRE

    Fritzsche, E; Hayatsu, H; Igloi, G L; Iida, S.; Kössel, H

    1987-01-01

    The use of permanganate as a reagent for DNA sequencing by chemical degradation has been studied with respect to its specificity for 5-methylcytosine residues. At weakly acidic pH and room temperature, 0.2 mM potassium permanganate reacts preferentially with thymine, 5-methylcytosine, and to a lesser extent with purine residues, while cytosine remains essentially intact. Permanganate oxidation is, therefore, a suitable DNA sequencing reaction for positive discrimination between 5-methylcytosi...

  2. Direct determination of 5-methylcytosine based on electrochemical activation of surfactant functionalized graphene modified pyrolytic graphite electrode

    International Nuclear Information System (INIS)

    Highlights: ► Surfactant functionalized graphene modified electrode was fabricated. ► Electrochemistry activation process significantly improved the electron transfer. ► This sensor could distinguish C and 5-mC at low potentials in a mixture solution. ► 5-mC could be detected when DNA bases existed by direct electrochemical way. -- Abstract: In this paper, a simple and sensitive method was proposed for 5-methylcytosine determination based on sodium dodecyl sulfate functionalized graphene (SDS-GR) modified pyrolytic graphite electrode (PGE), where SDS-GR was synthesized by electrolyzing graphite rod in 0.01 M SDS solution containing 0.1 M KNO3. After electrochemical activation by cyclic voltammetry (CV), activated SDS-GR modified PGE (A-SDS-GR/PGE) was fabricated for discriminating 5-methylcytosine from other nucleic acid bases. The results indicated that SDS-GR could improve the conductivity of the electrode and promote the electron transfer rate. And the process of electrochemical activation significantly enhanced the amount of active sites and oxygenated groups on electrode surface. As a result, 5-methylcytosine, guanine, adenine and cytosine could be distinguished with different oxidation potentials in a mixture solution except the overlap of the oxidation potential of thymine and 5-methylcytosine. However, the interference caused by thymine could be eliminated because the content of it is equal to adenine. The fabricated A-SDS-GR/PGE provided an alternative route for 5-methylcytosine determination when cytosine existed

  3. Oxidative damage to 5-methylcytosine in DNA.

    OpenAIRE

    Zuo, S; Boorstein, R J; Teebor, G.W.

    1995-01-01

    Exposure of pyrimidines of DNA to ionizing radiation under aerobic conditions or oxidizing agents results in attack on the 5,6 double bond of the pyrimidine ring or on the exocyclic 5-methyl group. The primary product of oxidation of the 5,6 double bond of thymine is thymine glycol, while oxidation of the 5-methyl group yields 5-hydroxymethyluracil. Oxidation of the 5,6 double bond of cytosine yields cytosine glycol, which decomposes to 5-hydroxycytosine, 5-hydroxyuracil and uracil glycol, al...

  4. Electrochemical detection of 5-methylcytosine in bisulfite-treated DNA

    Czech Academy of Sciences Publication Activity Database

    Bartošík, Martin; Fojta, Miroslav; Paleček, Emil

    2012-01-01

    Roč. 78, SEP (2012), s. 75-81. ISSN 0013-4686 R&D Projects: GA ČR(CZ) GAP301/11/2055; GA MŠk(CZ) ME09038 Institutional research plan: CEZ:AV0Z50040702 Keywords : DNA methylation * 5-methylcytosine analysis * sodium bisulfite Subject RIV: BO - Biophysics Impact factor: 3.777, year: 2012

  5. A plant DNA-binding protein that recognizes 5-methylcytosine residues.

    OpenAIRE

    Zhang, D. L.; Ehrlich, K C; Supakar, P C; Ehrlich, M

    1989-01-01

    A novel, 5-methylcytosine-specific, DNA-binding protein, DBP-m, has been identified in nuclear extracts of peas. DBP-m specifically recognizes 5-methylcytosine residues in DNA without appreciable DNA sequence specificity, unlike a mammalian DNA-binding protein (MDBP), which recognizes 5-methylcytosine residues but only in a related family of 14-base-pair sequences.

  6. Reprogramming of the paternal genome upon fertilization involves genome-wide oxidation of 5-methylcytosine

    OpenAIRE

    Iqbal, Khursheed; Jin, Seung-Gi; Pfeifer, Gerd P; Szabó, Piroska E.

    2011-01-01

    Genome-wide erasure of DNA cytosine-5 methylation has been reported to occur along the paternal pronucleus in fertilized oocytes in an apparently replication-independent manner, but the mechanism of this reprogramming process has remained enigmatic. Recently, considerable amounts of 5-hydroxymethylcytosine (5hmC), most likely derived from enzymatic oxidation of 5-methylcytosine (5mC) by TET proteins, have been detected in certain mammalian tissues. 5hmC has been proposed as a potential interm...

  7. Mutagenic and Cytotoxic Properties of Oxidation Products of 5-Methylcytosine Revealed by Next-Generation Sequencing

    OpenAIRE

    Xi-Wen Xing; Yu-Li Liu; Mario Vargas; Yinsheng Wang; Yu-Qi Feng; Xiang Zhou; Bi-Feng Yuan

    2013-01-01

    5-methylcytosine (5-mC) can be sequentially oxidized to 5-hydroxymethylcytosine (5-hmC), 5-formylcytosine (5-foC), and finally to 5-carboxylcytosine (5-caC), which is thought to function in active DNA cytosine demethylation in mammals. Although the roles of 5-mC in epigenetic regulation of gene expression are well established, the effects of 5-hmC, 5-foC and 5-caC on DNA replication remain unclear. Here we report a systematic study on how these cytosine derivatives (5-hmC, 5-foC and 5-caC) pe...

  8. Folic acid functionalized surface highlights 5-methylcytosine-genomic content within circulating tumor cells

    KAUST Repository

    Malara, Natalia

    2014-07-01

    Although the detection of methylated cell free DNA represents one of the most promising approaches for relapse risk assessment in cancer patients, the low concentration of cell-free circulating DNA constitutes the biggest obstacle in the development of DNA methylation-based biomarkers from blood. This paper describes a method for the measurement of genomic methylation content directly on circulating tumor cells (CTC), which could be used to deceive the aforementioned problem. Since CTC are disease related blood-based biomarkers, they result essential to monitor tumor\\'s stadiation, therapy, and early relapsing lesions. Within surface\\'s bio-functionalization and cell\\'s isolation procedure standardization, the presented approach reveals a singular ability to detect high 5-methylcytosine CTC-subset content in the whole CTC compound, by choosing folic acid (FA) as transducer molecule. Sensitivity and specificity, calculated for FA functionalized surface (FA-surface), result respectively on about 83% and 60%. FA-surface, allowing the detection and characterization of early metastatic dissemination, provides a unique advance in the comprehension of tumors progression and dissemination confirming the presence of CTC and its association with high risk of relapse. This functionalized surface identifying and quantifying high 5-methylcytosine CTC-subset content into the patient\\'s blood lead significant progress in cancer risk assessment, also providing a novel therapeutic strategy.© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Linking active DNA demethylation by Thymine DNA Glycosylase with epigenetic regulation of gene expression

    OpenAIRE

    Wirz, Annika

    2014-01-01

    The correct regulation of epigenetic modifications is crucial for cell plasticity and the establishment of cell identity. The underlying molecular mechanisms are not clear, but a role for DNA repair proteins has been implicated in this context, the investigation of which was the overall aim of my PhD thesis. The Thymine DNA Glycosylase (TDG) was described to excise the deamination products of cytosine (C) and 5-methylcytosine (5-mC), thereby initiating base excision repair (BER; Nedderman...

  10. Detection and mapping of 5-methylcytosine and 5-hydroxymethylcytosine with nanopore MspA.

    Science.gov (United States)

    Laszlo, Andrew H; Derrington, Ian M; Brinkerhoff, Henry; Langford, Kyle W; Nova, Ian C; Samson, Jenny Mae; Bartlett, Joshua J; Pavlenok, Mikhail; Gundlach, Jens H

    2013-11-19

    Precise and efficient mapping of epigenetic markers on DNA may become an important clinical tool for prediction and identification of ailments. Methylated CpG sites are involved in gene expression and are biomarkers for diseases such as cancer. Here, we use the engineered biological protein pore Mycobacterium smegmatis porin A (MspA) to detect and map 5-methylcytosine and 5-hydroxymethylcytosine within single strands of DNA. In this unique single-molecule tool, a phi29 DNA polymerase draws ssDNA through the pore in single-nucleotide steps, and the ion current through the pore is recorded. Comparing current levels generated with DNA containing methylated CpG sites to current levels obtained with unmethylated copies of the DNA reveals the precise location of methylated CpG sites. Hydroxymethylation is distinct from methylation and can also be mapped. With a single read, the detection efficiency in a quasirandom DNA strand is 97.5 ± 0.7% for methylation and 97 ± 0.9% for hydroxymethylation. PMID:24167255

  11. Incorporation of [14C]-orotic acid into DNA of regenerating rat liver results in a greater specific radioactivity of DNA-5-methylcytosines than DNA-cytosines

    International Nuclear Information System (INIS)

    To examine in vivo organization of events related to 5-methylcytosine (5-MC) occurrence in DNA, they determined the distribution of orotic acid incorporation into 5-MC vs cytosine (C) of rat liver DNA during liver compensatory hyperplasia. Rats were injected with 5 μCi of [6-14C]-orotic acid at 2 h intervals from 12 to 26 h post-partial hepatectomy. After a 2-h incorporation, livers were removed, DNA was isolated by Marmur's procedure and hydrolyzed by formic acid. Individual pyrimidines were isolated, quantitated by preparative and analytical high pressure liquid chromatography, and specific radioactivities determined. Two peaks of DNA synthesis were observed: a major peak at 18 h and a smaller peak at 22-24 h. The specific radioactivity of labeled thymine in DNA was approximately twice that of labeled C from 16 to 24 h. A more complex pattern was seen for labeling in 5-MC vs C during the same period. Values for 5-MC/C ratios increased to a maximum of 1.5 from 16 to 20 h, then decreased to 1.0 from 20 to 26 h. Thus in regenerating rat liver, [14C]-orotic acid label occurred to a 1.5-fold greater extent among DNA-5-MC than DNA-C during DNA synthesis. These results suggest the existence of mechanisms for: (a) preferential DNA synthesis in regions enriched in 5-MC content, or (b) different rates of turnover for 5-MC and C during DNA replication

  12. Dynamics of 5-methylcytosine and 5-hydroxymethylcytosine during germ cell reprogramming.

    Science.gov (United States)

    Yamaguchi, Shinpei; Hong, Kwonho; Liu, Rui; Inoue, Azusa; Shen, Li; Zhang, Kun; Zhang, Yi

    2013-03-01

    Previous studies have revealed that mouse primordial germ cells (PGCs) undergo genome-wide DNA methylation reprogramming to reset the epigenome for totipotency. However, the precise 5-methylcytosine (5mC) dynamics and its relationship with the generation of 5-hydroxymethylcytosine (5hmC) are not clear. Here we analyzed the dynamics of 5mC and 5hmC during PGC reprograming and germ cell development. Unexpectedly, we found a specific period (E8.5-9.5) during which both 5mC and 5hmC levels are low. Subsequently, 5hmC levels increase reaching its peak at E11.5 and gradually decrease until E13.5 likely by replication-dependent dilution. Interestingly, 5hmC is enriched in chromocenters during this period. While this germ cell-specific 5hmC subnuclear localization pattern is maintained in female germ cells even in mature oocytes, such pattern is gradually lost in male germ cells as mitotic proliferation resumes during the neonatal stage. Pericentric 5hmC plays an important role in silencing major satellite repeat, especially in female PGCs. Global transcriptome analysis by RNA-seq revealed that the great majority of differentially expressed genes from E9.5 to 13.5 are upregulated in both male and female PGCs. Although only female PGCs enter meiosis during the prenatal stage, meiosis-related and a subset of imprinted genes are significantly upregulated in both male and female PGCs at E13.5. Thus, our study not only reveals the dynamics of 5mC and 5hmC during PGC reprogramming and germ cell development, but also their potential role in epigenetic reprogramming and transcriptional regulation of meiotic and imprinted genes. PMID:23399596

  13. Similar kinetics for 5-methylcytosine and 5-hydroxymethylcytosine during human preimplantation development in vitro.

    Science.gov (United States)

    Petrussa, Laetitia; Van de Velde, Hilde; De Rycke, Martine

    2016-07-01

    After fertilization, the mammalian embryo undergoes epigenetic reprogramming with genome-wide DNA demethylation and subsequent remethylation. Oxidation of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC) was suggested to be an intermediate step in the DNA demethylation pathway. Other evidence, such as the stability of 5hmC in specific tissues, suggests that 5hmC constitutes a new epigenetic modification with its own biological function. Since few studies have been conducted on human material compared to animal models and species-specific epigenetic differences have been reported, we studied global DNA methylation and hydroxymethylation patterns in human in vitro preimplantation embryos using immunocytochemistry, comparing these patterns in good-quality and abnormally developing embryos. Our data showed that DNA methylation and hydroxymethylation modifications co-exist. 5mC and 5hmC signals were found in oocytes and in paternal and maternal pronuclei of zygotes, present in non-reciprocal patterns-which contrasts published data for the mouse. These two epigenetic modifications are present between Days 1 and 7 of in vitro development, with 5mC levels declining over cell divisions without noticeable remethylation during this period. A main decline in 5mC and 5hmC occurred as the embryo progressed from compaction to the blastocyst stage. No difference in (hydroxy)methylation was found between the inner cell mass and trophectoderm. When comparing normally and abnormally developing embryos, DNA (hydroxy)methylation reprogramming was abnormal in poor-quality embryos, especially during the first cleavages. Mol. Reprod. Dev. 83: 594-605, 2016 © 2016 Wiley Periodicals, Inc. PMID:27163211

  14. Whole-genome analysis of 5-hydroxymethylcytosine and 5-methylcytosine at base resolution in the human brain

    OpenAIRE

    Wen, Lu; Li, Xianlong; Yan, Liying; Tan, Yuexi; Li, Rong; Zhao, Yangyu; Wang, Yan; Xie, Jingcheng; Zhang, Yan; Song, Chunxiao; Yu, Miao; Liu, Xiaomeng; Zhu, Ping; Li, XiaoYu; Hou, Yu

    2014-01-01

    Background 5-methylcytosine (mC) can be oxidized by the tet methylcytosine dioxygenase (Tet) family of enzymes to 5-hydroxymethylcytosine (hmC), which is an intermediate of mC demethylation and may also be a stable epigenetic modification that influences chromatin structure. hmC is particularly abundant in mammalian brains but its function is currently unknown. A high-resolution hydroxymethylome map is required to fully understand the function of hmC in the human brain. Results We present gen...

  15. Pre-analytical variables of circulating cell-free nucleosomes containing 5-methylcytosine DNA or histone modification H3K9Me3

    DEFF Research Database (Denmark)

    Rasmussen, Louise; Herzog, Marielle; Aastrup rømer, Eva Christine;

    2016-01-01

    AIM: To evaluate pre-analytical variables of circulating cell-free nucleosomes containing 5-methylcytosine DNA (5mC) or histone modification H3K9Me3 (H3K9Me3). MATERIALS AND METHODS: Six studies were designed to assess the possible influence of pre-analytical variables. Study 1: influence of stasis...

  16. A 5-methylcytosine DNA glycosylase/lyase demethylates the retrotransposon Tos17 and promotes its transposition in rice

    KAUST Repository

    La, Honggui

    2011-09-06

    DNA 5-methylcytosine (5-meC) is an important epigenetic mark for transcriptional gene silencing in many eukaryotes. In Arabidopsis, 5-meC DNA glycosylase/lyases actively remove 5-meC to counter-act transcriptional gene silencing in a locus-specific manner, and have been suggested to maintain the expression of transposons. However, it is unclear whether plant DNA demethylases can promote the transposition of transposons. Here we report the functional characterization of the DNA glycosylase/lyase DNG701 in rice. DNG701 encodes a large (1,812 amino acid residues) DNA glycosylase domain protein. Recombinant DNG701 protein showed 5-meC DNA glycosylase and lyase activities in vitro. Knockout or knockdown of DNG701 in rice plants led to DNA hypermethylation and reduced expression of the retrotransposon Tos17. Tos17 showed less transposition in calli derived from dng701 knockout mutant seeds compared with that in wild-type calli. Overexpression of DNG701 in both rice calli and transgenic plants substantially reduced DNA methylation levels of Tos17 and enhanced its expression. The overexpression also led to more frequent transposition of Tos17 in calli. Our results demonstrate that rice DNG701 is a 5-meC DNA glycosylase/lyase responsible for the demethylation of Tos17 and this DNA demethylase plays a critical role in promoting Tos17 transposition in rice calli.

  17. Effects of Tet-mediated Oxidation Products of 5-Methylcytosine on DNA Transcription in vitro and in Mammalian Cells

    Science.gov (United States)

    You, Changjun; Ji, Debin; Dai, Xiaoxia; Wang, Yinsheng

    2014-11-01

    5-methylcytosine (5-mC) is a well-characterized epigenetic regulator in mammals. Recent studies showed that Ten-eleven translocation (Tet) proteins can catalyze the stepwise oxidation of 5-mC to produce 5-hydroxymethylcytosine (5-HmC), 5-formylcytosine (5-FoC) and 5-carboxylcytosine (5-CaC). The exciting discovery of these novel cytosine modifications has stimulated substantial research interests about their roles in epigenetic regulation. Here we systematically examined the effects of the oxidized 5-mC derivatives on the efficiency and fidelity of DNA transcription using a recently developed competitive transcription and adduct bypass assay. Our results showed that, when located on the transcribed strand, 5-FoC and 5-CaC exhibited marginal mutagenic and modest inhibitory effects on DNA transcription mediated by single-subunit T7 RNA polymerase or multi-subunit human RNA polymerase II in vitro and in human cells. 5-HmC displayed relatively milder blocking effects on transcription, and no mutant transcript could be detectable for 5-HmC in vitro or in cells. The lack of considerable mutagenic effects of the oxidized 5-mC derivatives on transcription was in agreement with their functions in epigenetic regulation. The modest blocking effects on transcription suggested that 5-FoC and 5-CaC may function in transcriptional regulation. These findings provided new evidence for the potential functional interplay between cytosine methylation status and transcription.

  18. Association of 5-methylcytosine and 5-hydroxymethylcytosine with mitochondrial DNA content and clinical and biochemical parameters in hepatocellular carcinoma.

    Directory of Open Access Journals (Sweden)

    Fan Shen

    Full Text Available Increasing epidemiological evidence has indicated that inherited variations of mitochondrial DNA (mtDNA copy number affect the genetic susceptibility of many malignancies in a tumour-specific manner and that DNA methylation also plays an important role in controlling gene expression during the differentiation and development of hepatocellular carcinoma (HCC. Our previous study demonstrated that HCC tissues showed a lower 5-hydroxymethylcytosine (5-hmC content when compared to tumour-adjacent tissues, but the relationship among 5-hmC, 5-methylcytosine (5-mC and mtDNA content in HCC patients is still unknown. This study aimed to clarify the correlation among mtDNA content, 5-mC and 5-hmC by quantitative real-time PCR and liquid chromatography tandem mass spectrometry analysis. We demonstrated that 5-hmC correlated with tumour size [odds ratio (OR 0.847, 95% confidence interval (CI 0.746-0.962, P = 0.011], and HCC patients with a tumour size ≥ 5.0 cm showed a lower 5-hmC content and higher levels of fasting plasma aspartate aminotransferase, the ratio of alanine aminotransferase to aspartate aminotransferase, γ-glutamyltransferase, alpha-fetoprotein than those with a tumour size <5 cm (all P<0.05. We further revealed that the mtDNA content of HCC tumour tissues was 225.97(105.42, 430.54 [median (25th Percentile, 75th Percentile] and was negatively correlated with 5-mC content (P = 0.035, but not 5-hmC content, in genomic DNA from HCC tumour tissues.

  19. Reduced 5-Methylcytosine Level as a Potential Progression Predictor in Patients with T1 or Non-Invasive Urothelial Carcinoma

    Directory of Open Access Journals (Sweden)

    Chi-Jung Chung

    2014-12-01

    Full Text Available This study aims to elucidate the level of DNA methylation in urothelial carcinomas (UCs using 5-methylcytosine (5-MeC immunohistochemistry (IHC. We examined the relationship among 5-MeC levels, DNA (cytosine-5-methyltransferase 1 (DNMT1 immunostaining levels, and clinicopathologic features. Tissue samples included 23 normal urothelia and 150 urothelial neoplasia, which comprised 40 non-invasive and 110 invasive UCs. The levels of 5-MeC and DNMT1 were assessed based on their immunoreactivities and then divided into low and high levels. In addition, we collected information on clinical variables, pathologic features, and recurrent status from patient questionnaires and medical records. Chi-square test and multivariate logistic regression model were used for analyses. Results showed that 5-MeC levels were positively associated with DNMT1 levels in UC (p = 0.0288. Both 5-MeC and DNMT1 were low in approximately 50% (76/150 of UC. The percentage of low 5-MeC levels was higher in invasive UC (65/110; 59% than in normal urothelia (2/23; 13% and non-invasive UC (18/40; 45%. Clinical factors were independently associated with low 5-MeC levels after adjusting for age and sex, including cancer stages II–IV, presence of UC in situ, and marked inflammation. Low 5-MeC levels in stage I invasive UC were not significantly different from those of non-invasive tumors (p = 0.8478. Low DNMT1 levels were only associated with UC with squamous differentiation (p = 0.0365. Neither 5-MeC nor DNMT1 levels were associated with UC recurrence. In conclusion, a low 5-MeC level could predict the progression of UC invasion into muscle.

  20. Eukaryotic rRNA Modification by Yeast 5-Methylcytosine-Methyltransferases and Human Proliferation-Associated Antigen p120.

    Directory of Open Access Journals (Sweden)

    Gabrielle Bourgeois

    Full Text Available Modified nucleotide 5-methylcytosine (m5C is frequently present in various eukaryotic RNAs, including tRNAs, rRNAs and in other non-coding RNAs, as well as in mRNAs. RNA:m5C-methyltranferases (MTases Nop2 from S. cerevisiae and human proliferation-associated nucleolar antigen p120 are both members of a protein family called Nop2/NSUN/NOL1. Protein p120 is well-known as a tumor marker which is over-expressed in various cancer tissues. Using a combination of RNA bisulfite sequencing and HPLC-MS/MS analysis, we demonstrated here that p120 displays an RNA:m5C- MTase activity, which restores m5C formation at position 2870 in domain V of 25S rRNA in a nop2Δ yeast strain. We also confirm that yeast proteins Nop2p and Rcm1p catalyze the formation of m5C in domains V and IV, respectively. In addition, we do not find any evidence of m5C residues in yeast 18S rRNA. We also performed functional complementation of Nop2-deficient yeasts by human p120 and studied the importance of different sequence and structural domains of Nop2 and p120 for yeast growth and m5C-MTase activity. Chimeric protein formed by Nop2 and p120 fragments revealed the importance of Nop2 N-terminal domain for correct protein localization and its cellular function. We also validated that the presence of Nop2, rather than the m5C modification in rRNA itself, is required for pre-rRNA processing. Our results corroborate that Nop2 belongs to the large family of pre-ribosomal proteins and possesses two related functions in pre-rRNA processing: as an essential factor for cleavages and m5C:RNA:modification. These results support the notion of quality control during ribosome synthesis by such modification enzymes.

  1. 5-Methylcytosine-DNA glycosylase activity is present in a cloned G/T mismatch DNA glycosylase associated with the chicken embryo DNA demethylation complex

    OpenAIRE

    Zhu, Bing; Zheng, Yong; Hess, Daniel; Angliker, Herbert; Schwarz, Steffen; Siegmann, Michel; Thiry, Stéphane; Jost, Jean-Pierre

    2000-01-01

    We previously have shown that DNA demethylation by chicken embryo 5-methylcytosine DNA glycosylase (5-MCDG) needs both RNA and proteins. One of these proteins is a RNA helicase. Further peptides were sequenced, and three of them are identical to the mammalian G/T mismatch DNA glycosylase. A 3,233-bp cDNA coding for the chicken homologue of human G/T mismatch DNA glycosylase was isolated and sequenced. The derived amino acid sequence (408 aa) shows 80% identity with the human G/T mismatch DNA ...

  2. Accurate Measurement of 5-Methylcytosine and 5-Hydroxymethylcytosine in Human Cerebellum DNA by Oxidative Bisulfite on an Array (OxBS-Array)

    OpenAIRE

    Field, Sarah F.; Beraldi, Dario; Bachman, Martin; Stewart, Sabrina K.; Beck, Stephan; Balasubramanian, Shankar

    2015-01-01

    The Infinium 450K Methylation array is an established tool for measuring methylation. However, the bisulfite (BS) reaction commonly used with the 450K array cannot distinguish between 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). The oxidative-bisulfite assay disambiguates 5mC and 5hmC. We describe the use of oxBS in conjunction with the 450K array (oxBS-array) to analyse 5hmC/5mC in cerebellum DNA. The “methylation” level derived by the BS reaction is the combined level of 5mC a...

  3. Natural Larval Diet Differently Influences the Pattern of Developmental Changes in DNA 5-Methylcytosine Levels in Apis mellifera Queens as Compared with Workers and Drones.

    Science.gov (United States)

    Strachecka, A; Olszewski, K; Bajda, M; Demetraki-Paleolog, J

    2015-08-01

    The principal mechanism of gene activation/silencing is DNA 5-methylcytosine methylation. This study was aimed at determining global DNA methylation levels in larvae, prepupae, pupae, and 1-day-old adults of Apis mellifera queens, workers and drones. The Imprint Methylated DNA Quantification Kit MDQ1 was used. Percentages of DNA 5-methylcytosine were low and relatively similar in the larvae of all the castes until 4th day of larval development (3-5%). However, they were higher in the drone and worker larvae than in the queen larvae. Generally, the developmental patterns of changes in the DNA methylation levels were different in the queens in comparison with the drones and workers. While methylation increased in the queens, it decreased in the drones and workers. Methylated DNA methylcytosine percentages and weights in the queen prepupae (15%, 9.18 ng) and pupae (21%, 10.74 ng) were, respectively, three and four times higher than in the worker/drone brood of the same age (2.5-4%, 0.03-0.07 ng). Only in the queens, after a substantial increase, did DNA methylation decrease almost twice between the pupal stage and queen emergence (from 21% and 10.74 ng to 12% and 6.78 ng). This finding seems very interesting, particularly for experimental gerontology. PMID:26547070

  4. Activation of tumor suppressor p53 gene expression by magnetic thymine-imprinted chitosan nanoparticles.

    Science.gov (United States)

    Lee, Mei-Hwa; Thomas, James L; Chen, Jian-Zhou; Jan, Jeng-Shiung; Lin, Hung-Yin

    2016-02-01

    Chitosan is a natural biodegradable polysaccharide that has been used to enhance gene delivery, owing to the ease with which chitosan nanoparticles enter the nucleus of cells. To study the effects of nuclear delivery of telomeric gene sequences, which contain thymine, we formed magnetic thymine-imprinted chitosan nanoparticles (TIPs) by the precipitation of chitosan, mixed with thymine and magnetic nanoparticles (to aid in separations). The mean size of the TIPS was 116 ± 18 nm; the dissociation constant for thymine was 21.8 mg mL(-1). We then treated human hepatocellular carcinoma (HepG2) with TIPs nanoparticles bearing bound thymine or a bound telomeric DNA sequence. The expression of the tumor suppressor p53 gene increased when TIPs were applied and decreased when telomere-bound TIPs were applied. PMID:26693943

  5. Distributive Processing by the Iron(II)/α-Ketoglutarate-Dependent Catalytic Domains of the TET Enzymes Is Consistent with Epigenetic Roles for Oxidized 5-Methylcytosine Bases.

    Science.gov (United States)

    Tamanaha, Esta; Guan, Shengxi; Marks, Katherine; Saleh, Lana

    2016-08-01

    The ten-eleven translocation (TET) proteins catalyze oxidation of 5-methylcytosine ((5m)C) residues in nucleic acids to 5-hydroxymethylcytosine ((5hm)C), 5-formylcytosine ((5f)C), and 5-carboxycytosine ((5ca)C). These nucleotide bases have been implicated as intermediates on the path to active demethylation, but recent reports have suggested that they might have specific regulatory roles in their own right. In this study, we present kinetic evidence showing that the catalytic domains (CDs) of TET2 and TET1 from mouse and their homologue from Naegleria gruberi, the full-length protein NgTET1, are distributive in both chemical and physical senses, as they carry out successive oxidations of a single (5m)C and multiple (5m)C residues along a polymethylated DNA substrate. We present data showing that the enzyme neither retains (5hm)C/(5f)C intermediates of preceding oxidations nor slides along a DNA substrate (without releasing it) to process an adjacent (5m)C residue. These findings contradict a recent report by Crawford et al. ( J. Am. Chem. Soc. 2016 , 138 , 730 ) claiming that oxidation of (5m)C by CD of mouse TET2 is chemically processive (iterative). We further elaborate that this distributive mechanism is maintained for TETs in two evolutionarily distant homologues and posit that this mode of function allows the introduction of (5m)C forms as epigenetic markers along the DNA. PMID:27362828

  6. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  7. The inactive X chromosome in the human female is enriched in 5-methylcytosine to an unusual degree and appears to contain more of this modified nucleotide than the remainder of the genome

    Indian Academy of Sciences (India)

    Deepti D. Deobagkar; H. Sharat Chandra

    2003-04-01

    By employing a procedure that combines ELISA and photoacoustic spectroscopy, we have examined the content of 5-methylcytosine (m5C) in DNA of individuals who differed from one another in the number of X chromosomes in their genomes. The results show that the human inactive X chromosome (Xi) contains very high amounts of this modified nucleotide. We estimate that in the 46,XX female there is more m5C in Xi (∼3.6 × 107) than in all the remaining chromosomes put together (∼2.1 × 107). Our results also suggest that nearly one-fifth of all cytosines in Xi are methylated and that, in addition to CpG methylation, there is extensive non-CpG methylation as well.

  8. Dithiothreitol-induced formation of thymine glycol in heated solutions of thymine or DNA

    International Nuclear Information System (INIS)

    Although it has been known for a number of years that autoxidation of thiols in solution generates hydroxyl radical ( . OH) through the iron-catalized and superoxide ion-dependent conversion of hydrogen peroxide, the magnitude of these effects on DNA and its constituent bases has yet to be determined. The authors measured thymine glycol (TG), a major product of thymine- . OH reactions, in phosphate-buffered (10 mM, pH 7) solutions of thymine and dithiothreitol (DTT, 0.01-20 mM) and in similar solutions containing single-stranded or double-stranded DNA. TG is readily produced in heated (450C) or refrigerated (50C) thymine-DTT mixtures. After 2 hr of heating (450C), TG yield is equivalent to that produced in thymine solutions irradiated to 50 Gy (in O/sub 2/). Disodium-EDTA (0.5 mM) produced a 7-fold increase in TG formation whereas diethylenetriaminepentaacetic acid (DTPA, 1 mM) inhibited TG production. The actions of these chelators strongly suggest that iron (present as a contaminant in the phosphate buffer) is required for the production of TG. Preliminary results show that TG yields in DTT-treated (10 mM) and heated DNA (450 x 4 hr) are reduced in comparison to the yields obtained with free thymine. This work provides additional - molecular-level - evidence that thiol autoxidation might explain the enhanced toxicity of thiols in heated cells

  9. Comparison of Alpha- and Gamma-Ray Radiolysis of Thymine

    International Nuclear Information System (INIS)

    The radiolysis of thymine with polonium-210 alpha particles shows that qualitatively the same products of radiolysis are formed as with X- or gamma rays. In the presence of oxygen thymine hydroperoxide and thymine glycols are the main products of radiolysis with alpha rays. The amount of thymine hydroperoxide is about 30% of all products formed. In the absence of oxygen, thymine glycols, dihydrothymine and its monohydro- xyderivatives and 5-hydroxymethyluracil are formed. These results prove that the OH radical is the main species taking part in the alpha radiolysis of thymine. The presence of dihydrothymine and its derivatives shows the H atom to take part also in the splitting of thymine by alpha particles. Among other products of alpha radiolysis there is a higher percentage of urea and 5-hydroxymethyluracil if compared with gamma rays. (author)

  10. On the Formation of Thymine Photodimers in Thymine Single Strands and Calf Thymus DNA

    DEFF Research Database (Denmark)

    Baggesen, Lisbeth Munksgård; Hoffmann, S.V.; Nielsen, Steen Brøndsted

    2014-01-01

    Solar light leads to thymine dimers that are mutagenic and primary cause of skin cancer. Here, we report absorption and synchrotron radiation circular dichroism (CD) spectra of Tn single strands with different number n of bases (n = 2–7, 10, 11) recorded after various 254 nm irradiation times. Fr...

  11. The effect of microhydration on ionization energies of thymine

    Energy Technology Data Exchange (ETDEWEB)

    Khistyev, Kirill; Bravaya, Ksenia B.; Kamarchik, Eugene; Kostko, Oleg; Ahmed, Musahid; Krylov, Anna I.

    2011-01-03

    A combined theoretical and experimental study of the effect of microhydration on ionization energies (IEs) of thymine is presented. The experimental IEs are derived from photoionization efficiency curves recorded using tunable synchrotron VUV radiation. The onsets of the PIE curves are 8.85+-0.05, 8.60+-0.05, 8.55+-0.05, and 8.40+-0.05 eV for thymine, thymine mono-, di-, and tri-hydrates, respectively. The computed (EOM-IP-CCSD/cc-pVTZ) AIEs are 8.90, 8.51, 8.52, and 8.35 eV for thymine and the lowest isomers of thymine mono-, di-, and tri-hydrates. Due to large structural relaxation, the Franck-Condon factors for the 0<-- 0 transitions are very small shifting the apparent PIE onsets to higher energies. Microsolvation strongly affects IEs of thymine -- addition of each water molecule reduces the first vertical IE by 0.10-0.15 eV. The adiabatic IE decreases even more (up to 0.4 eV). The magnitude of the effect varies for different ionized states and for different isomers. For the ionized states that are localized on thymine the dominant contribution to the IE reduction is the electrostatic interaction between the delocalized positive charge on thymine and the dipole moment of the water molecule.

  12. Photosensitization of bioinspired thymine-containing polymers.

    Science.gov (United States)

    Martino, Debora M; Reyna, Dalila; Estenoz, Diana A; Trakhtenberg, Sofia; Warner, John C

    2008-05-29

    Here, we report a sensitization study on a family of water-soluble photopolymers based on thymine. The goal of this study was to determine whether the presence of sensitizer molecules would promote photocrosslinking/immobilization of the polymers using low-energy irradiation (520 nm) as compared to the UV irradiation (approximately 280 nm) necessary for the standard photoinduced process to take place. With the aid of Eosin Y Spirit Soluble (EY) as a sensitizer, water-soluble polystyrene copolymers of vinylbenzylthymine-vinylbenzyltriethylammonium chloride (VBT-VBA) were immobilized after exposure to visible irradiation. By exciting the sensitizer molecule in the presence of VBT copolymers at a wavelength where absorption by the latter does not occur, the triplet state of the sensitizer is generated in high yields, and consequently, polymer photocross-linking takes place. UV-vis spectroscopy has been used to study the effect of irradiation dose, copolymer composition, and sensitizer concentration on the photoreactivity of VBT polymers. These studies demonstrate the feasibility of using Eosin Y as a sensitizer to achieve the thymine photodimer formation, resulting in immobilization of VBT-VBA-EY films on PET substrate. This provides complementary information on photoinduced immobilization of VBT-VBA films that are crucial for developing new classes of environmentally benign materials and new energy-saving methods. PMID:18457375

  13. Local piezoresponse and polarization switching in nucleobase thymine microcrystals

    Science.gov (United States)

    Bdikin, Igor; Heredia, Alejandro; Neumayer, Sabine M.; Bystrov, Vladimir S.; Gracio, José; Rodriguez, Brian J.; Kholkin, Andrei L.

    2015-08-01

    Thymine (2-oxy-4-oxy-5 methyl pyrimidine) is one of the four nucleobases of deoxyribonucleic acid (DNA). In the DNA molecule, thymine binds to adenine via two hydrogen bonds, thus stabilizing the nucleic acid structure and is involved in pairing and replication. Here, we show that synthetic thymine microcrystals grown from the solution exhibit local piezoelectricity and apparent ferroelectricity, as evidenced by nanoscale electromechanical measurements via Piezoresponse Force Microscopy. Our experimental results demonstrate significant electromechanical activity and polarization switchability of thymine, thus opening a pathway for piezoelectric and ferroelectric-based applications of thymine and, perhaps, of other DNA nucleobase materials. The results are supported by molecular modeling of polarization switching under an external electric field.

  14. Radiation-induced crosslinks between thymine and phenylalanine

    Energy Technology Data Exchange (ETDEWEB)

    Dizdaroglu, M.; Simic, M.G. (National Bureau of Standards, Gaithersburg, MD (USA))

    1985-01-01

    OH radicals generated by ionizing radiation in aqueous solutions of thymine (T) and phenylalanine (Phe) induced crosslinking between thymine and phenylalanine. The crosslinked products were isolated and characterized by capillary gas chromatography-mass spectrometry. They are formed via OH radical adducts to thymine and phenylalanine and the reaction between dissimilar radicals is greatly favoured (T-Phe:Phe-Phe:T-T=0.46:0.14:0.05). The reaction mechanism presented may serve as a model for radiation or any free radical-induced crosslinks between DNA and proteins.

  15. The self assembly of thymine at Au(110)/liquid interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Molina Contreras, J.R. [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Mexico (Mexico); Smith, C.I.; Bowfield, A.; Weightman, P. [Physics Department, University of Liverpool (United Kingdom); Tillner, F. [Fachbereich Physik, Universitaet Konstanz (Germany)

    2012-06-15

    We show that thymine self-assembles into an ordered structure when adsorbed at a Au(110)/liquid interface. Reflection anisotropy spectroscopy (RAS) shows that as found for cytosine and adenine the adsorbed thymine molecules are oriented essentially vertically on the Au(110) surface with the molecule aligned along one of the principal axes of the Au(110) surface. Simulations of the RA spectra to an empirical model indicates that as found for adsorbed cytosine and adenine, thymine is aligned along the [1 anti 10] direction on the Au(110) surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Electron accommodation dynamics in the DNA base thymine

    International Nuclear Information System (INIS)

    The dynamics of electron attachment to the DNA base thymine are investigated using femtosecond time-resolved photoelectron imaging of the gas phase iodide-thymine (I−T) complex. An ultraviolet pump pulse ejects an electron from the iodide and prepares an iodine-thymine temporary negative ion that is photodetached with a near-IR probe pulse. The resulting photoelectrons are analyzed with velocity-map imaging. At excitation energies ranging from −120 meV to +90 meV with respect to the vertical detachment energy (VDE) of 4.05 eV for I−T, both the dipole-bound and valence-bound negative ions of thymine are observed. A slightly longer rise time for the valence-bound state than the dipole-bound state suggests that some of the dipole-bound anions convert to valence-bound species. No evidence is seen for a dipole-bound anion of thymine at higher excitation energies, in the range of 0.6 eV above the I−T VDE, which suggests that if the dipole-bound anion acts as a “doorway” to the valence-bound anion, it only does so at excitation energies near the VDE of the complex

  17. Photoaddition of p-aminobenzoil acid to thymine and thymidine

    International Nuclear Information System (INIS)

    Several studies in the literature have shown that DNA is damaged after UV irradiation in the presence of the sunscreen agent p-aminobenzoic acid (PABA), both in vivo and in vitro. One type of damage has been shown to be the result of increased yields of pyrimidime cyclobutane dimer formation. However, it has been suggested that other types of lesions are produced as well. We have studied the photochemistry of the thymine-PABA and thymidine-PABA systems and report here the isolation and characterization of thymine-PABA and thymidine-PABA photoadducts. These products have been identified, respectively as 5-(2-amino-5-carboxyphenyl)-5,6-dihydrothymine and isomeric forms of 5-(2-amino-5-carboxyphenyl)-5,6-dihydrothymidine. The quantum yields for the formation of these ducts in deaerated aqueous solutions at pH 7.0 have been determined to be 9.5 x 10-4 and 4.3 x 10-3 for the thymine and thymidine based adducts respectively. A pH profile for the thymine-PABA system indicated a maximum quantum yield for adduct formation at pH 6.5, although it could be detected over the whole pH range studied (pH 3.5-11.0). (Author)

  18. Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency

    OpenAIRE

    Anna K. Ciuk; Lindhorst, Thisbe K

    2015-01-01

    Multivalency effects are essential in carbohydrate recognition processes as occurring on the cell surface. Thus many synthetic multivalent glycoconjugates have been developed as important tools for glycobiological research. We are expanding this collection of molecules by the introduction of carbohydrate-scaffolded divalent glycothymine derivatives that can be intramolecularily dimerized by [2 + 2] photocycloaddition. Thus, thymine functions as a control element that allows to restrict the co...

  19. Density Functional Theory Study on Interaction between Catechin and Thymine

    Institute of Scientific and Technical Information of China (English)

    Wan-fei Cai; Yan Zheng; Lai-cai Li; An-min Tian

    2012-01-01

    The interacting patterns and mechanism of the catechin and thymine have been investigated with the density functional theory Becke's three-parameter nonlocal exchange functional and the Lee,Yang,and Parr nonlocal correlation functional (B3LYP) method by 6-31+G* basis set.Thirteen stable structures for the catechin-thymine complexes have been found which form two hydrogen bonds at least.The vibrational frequencies are also studied at the same level to analyze these complexes.The results indicated that catechin interacted with thymine by three different hydrogen bonds as N-H…O,C-H…O,O-H…O and the complexes are mainly stabilized by the hydrogon bonding interactions.Theories of atoms in molecules and natural bond orbital have been adopted to investigate the hydrogen bonds involved in all systems.The interaction energies of all complexes have been corrected for basis set superposition error,which are from-18.15 kJ/mol to 32.99 kJ/mol.The results showed that the hydrogen bonding contribute to the interaction energies dominantly,The corresponding bonds stretching motions in all complexes are red-shifted relative to that of the monomer,which is in agreement with experimental results.

  20. Kinetics and mechanism of protection of thymine from sulphate radical anion under anoxic conditions

    Indian Academy of Sciences (India)

    M Sudha Swaraga; M Adinarayana

    2003-04-01

    The rates of photooxidation of thymine in presence of peroxydisulphate (PDS) have been determined by measuring the absorbance of thymine at 264 nm spectrophotometrically. The rates and the quantum yields () of oxidation of thymine by sulphate radical anion have been determined in the presence of different concentrations of caffeic acid. Increase in [caffeic acid] is found to decrease the rate of oxidation of thymine suggesting that caffeic acid acts as an efficient scavenger of SO$^{\\bullet -}_{4}$ and protects thymine from it. Sulphate radical anion competes for thymine as well as for caffeic acid. The rate constant of sulphate radical anion with caffeic acid has been calculated to be 1.24 × 1010 dm3 mol-1 s-1. The quantum yields of photooxidation of thymine have been calculated from the rates of oxidation of thymine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to sulphate radical anion. From the results of experimentally determined quantum yields (exptl) and the quantum yields calculated (cl) assuming caffeic acid acting only as a scavenger of SO$^{\\bullet -}_{4}$ radicals show that exptl values are lower than cl values. The ' values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for SO$^{\\bullet-}_{4}$ scavenging by caffeic acid, are also found to be greater than exptl values. These observations suggest that the thymine radicals are repaired by caffeic acid in addition to scavenging of sulphate radical anions.

  1. Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency.

    Science.gov (United States)

    Ciuk, Anna K; Lindhorst, Thisbe K

    2015-01-01

    Multivalency effects are essential in carbohydrate recognition processes as occurring on the cell surface. Thus many synthetic multivalent glycoconjugates have been developed as important tools for glycobiological research. We are expanding this collection of molecules by the introduction of carbohydrate-scaffolded divalent glycothymine derivatives that can be intramolecularily dimerized by [2 + 2] photocycloaddition. Thus, thymine functions as a control element that allows to restrict the conformational flexibility of the scaffolded sugar ligands and thus to "organize" multivalency. With this work we add a parameter to multivalency studies additional to valency. PMID:26124869

  2. Analysis of products of thymine irradiated by 18O8+ ion beam in N2O saturated aqueous solution

    International Nuclear Information System (INIS)

    Some methods of capillary gas chromatography, such as GC, GC-MS GC-FT-IR, are used to analyze the products of thymine irradiated by 18O8+ ion beam in N2O saturated aqueous solution. From the results of GC-MS the molecular weight of products can be determined, and from the results of GC-FT-IR some molecular structure information of products can be obtained. By this way the products, 5,6-Dihydro-thymine, 5-Hydroxyl-5-Methylhydantoin, 5-Hydroxyl-6-Hydro-thymine, 5-Hydro-6-Hydroxyl thymine, 5-Hydroxymethyluracil, Trans-Thymine glycol, Cis-Thymine glycol and dimers are determined without separation of them from samples. Though these products are as same as those products of thymine irradiated by γ rays in N2O saturated aqueous solution, the mechanism of thymine irradiated by heavy ion beam in aqueous solution is different from that by γ rays. The main products of thymine irradiated by 18O8+ ion beam in N2O saturated aqueous solution are hydroxyl adducts at 5-6 band of thymine, while the main products of thymine irradiated by γ ray in N2O saturated aqueous solution are dimers of thymine

  3. Detection of thymine [2+2] photodimer repair in DNA: selective reaction of KMnO4.

    OpenAIRE

    Ramaiah, D; Koch, T.; Orum, H; Schuster, G B

    1998-01-01

    The specific reaction of potassium permanganate with thymine in single-stranded DNA was employed to analyze thymine [2+2] dimer repair in DNA and in DNA/peptide nucleic acid hybrid duplexes. This simple and highly sensitive chemical assay is convenient for monitoring repair of thymine dimers in oligonucleotides.

  4. Linoleic acid, thymine, and tryptophan radiosensitization by protoporphyrin in presence of oxygene

    International Nuclear Information System (INIS)

    Sensitizing effect induced by protoporphyrin, an active molecule in photooxidation is studied. Studied substances are tryptophan, thymine, linoleic acid, each component representing one of the great groups of biological components, nucleic acid, proteins, lipids

  5. Internal Energies of Ion-Sputtered Neutral Tryptophan and Thymine Molecules Determined by Vacuum Ultraviolet Photoionization

    OpenAIRE

    Zhou, Jia

    2010-01-01

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi3 + in...

  6. Characteristics of thymine dimer excision from xeroderma pigmentosum chromatin

    International Nuclear Information System (INIS)

    We investigated thymine dimer excision from xeroderma pigmentosum (XP) chromatin in the cell-free reconstruction system. The normal-cell extract performed specific dimer excision from native chromatin and DNA isolated from 100 J/m2-irradiated cells. Such an excision in vitro was rapid and required high concentrations of extract. The extracts of XP group A, C and G cells were unable to excise from their own native-chromatin, but capable of excising from chromatin deprived of loosely bound nonhistone proteins with 0.35 M NaCl, as were from purified DNA. Thus, group A, C and G cells are most likely to be defective in the specific XP factors facilitating the excising activity under multicomponent regulation at the chromatin level. Further, either of group A, C and G extracts successfully complemented the native chromatin of the alternative groups. Uniquely, the XP group D extract excised dimers from native chromatin in the normal fashion under the condition. These results suggest that XP group A, C, D and G cells examined may not be defective in the dimer specific endonuclease and exonuclease per se. 19 references, 3 figures, 2 tables

  7. Internal Energies of Ion-Sputtered Neutral Tryptophan and Thymine Molecules Determined by Vacuum Ultraviolet Photoionization

    International Nuclear Information System (INIS)

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi3 + indicates that the ion-sputtered parent molecules have ∼2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi3 + ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis.

  8. Internal energies of ion-sputtered neutral tryptophan and thymine molecules determined by vacuum ultraviolet photoionization.

    Science.gov (United States)

    Zhou, Jia; Takahashi, Lynelle K; Wilson, Kevin R; Leone, Stephen R; Ahmed, Musahid

    2010-05-01

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi(3)(+) indicates that the ion-sputtered parent molecules have approximately 2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi(3)(+) ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis. PMID:20353160

  9. Internal Energies of Ion-Sputtered Neutral Tryptophan and Thymine Molecules Determined by Vacuum Ultraviolet Photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jia; Takahashi, Lynelle; Wilson, Kevin R.; Leone, Stephen R.; Ahmed, Musahid

    2010-03-11

    Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi3 + indicates that the ion-sputtered parent molecules have ~;;2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi3 + ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis.

  10. A DNA glycosylase from human lymphoblasts that releases cis-thymine glycol from oxidized DNA

    International Nuclear Information System (INIS)

    An endonuclease (termed the UVX endonuclease) partially purified from cultured human leukemic lymphoblasts (CEM-CCRF line) was previously shown to act specifically on DNA irradiated by ionizing radiation, UV light, or treated with osmium tetroxide. This activity is tightly associated with an endonuclease specific for apurinic /apyrimidinic (AP) sites in DNA, suggesting that the initial attack on the radiation or oxidation induced lesions is by a DNA glycosylase that generates such AP sites. Thymine glycol has been shown to be a product common to γ-irradiated and oxidized DNA and in the present studies the authors have shown that the UVX endonuclease releases free cis-thymine glycol from osmium tetroxide treated DNA. HPLC analysis of the reaction products failed to detect any cis-thymidine glycol or nucleotide material indicating that the activity responsible is truly a DNA glycosylase. This enzyme thus resembles Endonuclease III of E. coli which contains both AP endonuclease and thymine glucol-DNA glycosylase activities

  11. Transcriptional regulation of thymine DNA glycosylase (TDG) by the tumor suppressor protein p53

    OpenAIRE

    da Costa, Nathalia Meireles; Hautefeuille, Agnès; Cros, Marie-Pierre; Melendez, Matias Eliseo; Waters, Timothy; Swann, Peter; Hainaut, Pierre; Pinto, Luis Felipe Ribeiro

    2012-01-01

    Thymine DNA glycosylase (TDG) belongs to the superfamily of uracil DNA glycosylases (UDG) and is the first enzyme in the base-excision repair pathway (BER) that removes thymine from G:T mismatches at CpG sites. This glycosylase activity has also been found to be critical for active demethylation of genes involved in embryonic development. Here we show that wild-type p53 transcriptionally regulates TDG expression. Chromatin immunoprecipitation (ChIP) and luciferase assays indicate that wild-ty...

  12. Defective thymine dimer excision by cell-free extracts of xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    Crude extracts of normal human diploid fibroblasts and of human peripheral blood lymphocytes excise thymine dimers from purified ultraviolet-irradiated DNA, or from the DNA presumably present as chromatin in unfractionated cell-free preparations of cells that had been labeled with [3H]thymidine. Extracts of xeroderma pigmentosum cells from complementation groups A, C, and D also excise thymine dimers from purified DNA, but extracts of group A cells do not excise dimers from the DNA of radioactively labeled unfractionated cell-free preparations

  13. Low-energy Electron Collisions with Gas-phase Thymine Molecule

    Directory of Open Access Journals (Sweden)

    Irina V. CHERNYSHOVA

    2011-09-01

    Full Text Available The paper presents an investigation of the negative ion formation of the thymine (T molecule. The formation of negative ions by electron impact of this molecule is measured. The quantum mechanical investigations are performed to calculate the electron attachment cross section, the force constants, the resulting vibrational frequencies and intensities. The absorption spectrum and their nature are investigated too. The obtained results allows us to foresee the mechanism of production of the [T-H]- ion and explain the origin of some features in the experimental negative ion formation of the thymine molecule.http://dx.doi.org/10.5755/j01.ms.17.3.601

  14. A convenient, high-yield synthesis of 1-substituted uracil and thymine derivatives

    Czech Academy of Sciences Publication Activity Database

    Rejman, Dominik; Kovačková, Soňa; Pohl, Radek; Rosenberg, Ivan

    Manchester : University of Manchester, 2009. s. 70-70. [Nucleic Acids at the Chemistry - Biology Interface. 07.09.2009-08.09.2009, Manchester] R&D Projects: GA MZd NR9138; GA MŠk 2B06065 Institutional research plan: CEZ:AV0Z40550506 Keywords : uracil * thymin Subject RIV: CC - Organic Chemistry

  15. Ternary DNA chip based on a novel thymine spacer group chemistry.

    Science.gov (United States)

    Yang, Yanli; Yildiz, Umit Hakan; Peh, Jaime; Liedberg, Bo

    2015-01-01

    A novel thymine-based surface chemistry suitable for label-free electrochemical DNA detection is described. It involves a simple two-step sequential process: immobilization of 9-mer thymine-terminated probe DNAs followed by backfilling with 9-mer thymine-based spacers (T9). As compared to commonly used organic spacer groups like 2-mercaptoethanol, 3-mercapto-1-propanol and 6-mercapto-1-hexanol, the 9-mer thymine-based spacers offer a 10-fold improvement in discriminating between complementary and non-complementary target hybridization, which is due mainly to facilitated transport of the redox probes through the probe-DNA/T9 layers. Electrochemical measurements, complemented with Surface Plasmon Resonance (SPR) and Quartz Crystal Microbalance (QCM-D) binding analyses, reveal that optimum selectivity between complementary and non-complementary hybridization is obtained for a sensing surface prepared using probe-DNA and backfiller T9 at equimolar concentration (1:1). At this particular ratio, the probe-DNAs are preferentially oriented and easily accessible to yield a sensing surface with favorable hybridization and electron transfer characteristics. Our findings suggest that oligonucleotide-based spacer groups offer an attractive alternative to short organic thiol spacers in the design of future DNA biochips. PMID:25465760

  16. Effect of serotonin on the yield of UV-induced thymine dimers in DNA

    International Nuclear Information System (INIS)

    Using fluorescence method serotonin interaction with DNA is studied and bond constant Ksub(c)=4.2x104 M-1 is defined. It is shown that bound serotonin reduces yield of UV-induced thymine dimers. Value of efficient distance of protective serotonin effect constituting part of DNA chain of 4 base pairs, is determined

  17. Mechanisms for the formation of thymine under astrophysical conditions and implications for the origin of life

    Science.gov (United States)

    Bera, Partha P.; Nuevo, Michel; Materese, Christopher K.; Sandford, Scott A.; Lee, Timothy J.

    2016-04-01

    Nucleobases are the carriers of the genetic information in ribonucleic acid and deoxyribonucleic acid (DNA) for all life on Earth. Their presence in meteorites clearly indicates that compounds of biological importance can form via non-biological processes in extraterrestrial environments. Recent experimental studies have shown that the pyrimidine-based nucleobases uracil and cytosine can be easily formed from the ultraviolet irradiation of pyrimidine in H2O-rich ice mixtures that simulate astrophysical processes. In contrast, thymine, which is found only in DNA, is more difficult to form under the same experimental conditions, as its formation usually requires a higher photon dose. Earlier quantum chemical studies confirmed that the reaction pathways were favorable provided that several H2O molecules surrounded the reactants. However, the present quantum chemical study shows that the formation of thymine is limited because of the inefficiency of the methylation of pyrimidine and its oxidized derivatives in an H2O ice, as supported by the laboratory studies. Our results constrain the formation of thymine in astrophysical environments and thus the inventory of organic molecules delivered to the early Earth and have implications for the role of thymine and DNA in the origin of life.

  18. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  19. Thermodynamic Potential for the Abiotic Synthesis of Adenine, Cytosine, Guanine, Thymine, Uracil, Ribose, and Deoxyribose in Hydrothermal Systems

    NARCIS (Netherlands)

    LaRowe, D.E.; Regnier, P.

    2008-01-01

    The thermodynamic potential for the abiotic synthesis of the five common nucleobases (adenine, cytosine, guanine, thymine, and uracil) and two monosaccharides (ribose and deoxyribose) from formaldehyde and hydrogen cyanide has been quantified under temperature, pressure, and bulk composition conditi

  20. First-principles and semi-empirical van der Waals study of thymine on Cu(110) surface

    OpenAIRE

    Caciuc, V.; Atodiresei, N.; Lazic, P.; Morikawa, Y; Blugel, S.

    2008-01-01

    In this study we investigated by means of density functional theory calculations the adsorption geometry and bonding mechanism of a single thymine (C$_5$H$_6$N$_2$O$_2$) molecule on Cu(110) surface. In the most stable energetic configuration, the molecular plane is oriented perpendicular to substrate along the $[1\\bar{1}0]$ direction. For this adsorption geometry, the thymine molecule interacts with the surface via a deprotonated nitrogen atom and two oxygen ones such that the bonding mechani...

  1. Synthesis of Novel Aliphatic N-sulfonylamidino Thymine Derivatives by Cu(I)-catalyzed Three-component Coupling Reaction

    OpenAIRE

    Krstulović, Luka; Ismaili, Hamit; Višnjevac, Aleksandar; Glavaš-Obrovac, Ljubica; Žinić, Biserka

    2012-01-01

    A series of new aliphatic N-sulfonylamidino thymine derivatives containing nucleobase, N-sulfonyl and amidine pharmacophores in the structure were synthesized by Cu(I)-catalyzed threecomponent coupling of 1-propargyl thymine, benzenesulfonyl azides and amines or ammonium salts. Preliminary in vitro antitumor screening (human cervix adenocarcinoma -HeLa and leukemia cells - Jurkat) revealed promising activities of N,N-diethyl- (2) and N-4-cyanobenzyl- (6) derivatives of 4-acetamido...

  2. Production of thymine glycols in DNA by radiation and chemical carcinogens as detected by a monoclonal antibody.

    OpenAIRE

    Leadon, S A

    1987-01-01

    In order to understand the role in carcinogenesis of damage indirectly induced by chemical carcinogens, it is important to identify the primary DNA lesions. We have measured the formation and repair of one type of DNA modification, 5,6-dihydroxydihydrothymine (thymine glycol), following exposure of cultured human cells to the carcinogens N-hydroxy-2-naphthylamine or benzo(a)pyrene. The efficiency of production of thymine glycols in DNA by these carcinogens was compared to that by ionizing rad...

  3. Temperature dependence of the cross section for the fragmentation of thymine via dissociative electron attachment

    Energy Technology Data Exchange (ETDEWEB)

    Kopyra, Janina [Faculty of Science, Siedlce University, 3 Maja 54, 08-110 Siedlce (Poland); Abdoul-Carime, Hassan, E-mail: hcarime@ipnl.in2p3.fr [Université de Lyon, Université Claude Bernard Lyon1, Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, 43 Bd du 11 novembre 1918, 69622 Villeurbanne Cedex (France)

    2015-05-07

    Providing experimental values for absolute Dissociative Electron Attachment (DEA) cross sections for nucleobases at realistic biological conditions is a considerable challenge. In this work, we provide the temperature dependence of the cross section, σ, of the dehydrogenated thymine anion (T − H){sup −} produced via DEA. Within the 393-443 K temperature range, it is observed that σ varies by one order of magnitude. By extrapolating to a temperature of 313 K, the relative DEA cross section for the production of the dehydrogenated thymine anion at an incident energy of 1 eV decreases by 2 orders of magnitude and the absolute value reaches approximately 6 × 10{sup −19} cm{sup 2}. These quantitative measurements provide a benchmark for theoretical prediction and also a contribution to a more accurate description of the effects of ionizing radiation on molecular medium.

  4. Formation of positive and negative ions of thymine molecules under the action of slow electrons

    Science.gov (United States)

    Shafranyosh, I. I.; Sukhoviya, M. I.; Shafranyosh, M. I.; Shimon, L. L.

    2008-12-01

    The formation of positive and negative molecules of thymine—a base of nucleic acids—under the action of slow electrons is investigated by the method of crossed electron and molecular beams. The method developed makes it possible to measure the molecular beam intensity and determine the energy dependences and absolute values of total cross sections for the formation of positive and negative ions of thymine molecules. It is found that the maximal cross section for the formation of positive ions is reached at an energy of 95 eV and its absolute value is, accordingly, 1.4 × 10-15 cm2. The total cross section for the formation of negative ions is 8.2 × 10-18 cm2 at an energy of 1.1 eV. The mass spectra of thymine molecules are measured and the cross sections of dissociative ionization are determined.

  5. Functionalized gold nanoparticles/reduced graphene oxide nanocomposites for ultrasensitive electrochemical sensing of mercury ions based on thymine-mercury-thymine structure.

    Science.gov (United States)

    Wang, Nan; Lin, Meng; Dai, Hongxiu; Ma, Houyi

    2016-05-15

    A sensitive, selective and reusable electrochemical biosensor for the determination of mercury ions (Hg(2+)) has been developed based on thymine (T) modified gold nanoparticles/reduced graphene oxide (AuNPs/rGO) nanocomposites. Graphene oxide (GO) was electrochemically reduced on a glassy carbon substrate. Subsequently, AuNPs were deposited onto the surface of rGO by cyclic voltammetry. For functionalization of the electrode, the carboxylic group of the thymine-1-acetic acid was covalently coupled with the amine group of the cysteamine which self-assembled onto AuNPs. The structural features of the T bases functionalized AuNPs/rGO electrode were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) spectroscopy. Each step of the modification process was characterized by cyclic voltammetry (CV) and electrochemical impedence spectroscopy (EIS). The T bases modified AuNPs/rGO electrode was applied to detect various trace metal ions by differential pulse voltammetry (DPV). The proposed biosensor was found to be highly sensitive to Hg(2+) in the range of 10ng/L-1.0µg/L. The biosensor afforded excellent selectivity for Hg(2+) against other heavy metal ions such as Zn(2+), Cd(2+), Pb(2+), Cu(2+), Ni(2+), and Co(2+). Furthermore, the developed sensor exhibited a high reusability through a simple washing. In addition, the prepared biosensor was successfully applied to assay Hg(2+) in real environmental samples. PMID:26720921

  6. A convenient, high-yield synthesis of 1-substituted uracil and thymine derivatives

    Czech Academy of Sciences Publication Activity Database

    Rejman, Dominik; Kovačková, Soňa; Pohl, Radek; Dračínský, Martin; Fiedler, Pavel; Rosenberg, Ivan

    2009-01-01

    Roč. 65, č. 41 (2009), s. 8513-8523. ISSN 0040-4020 R&D Projects: GA MŠk(CZ) LC06077; GA MŠk(CZ) LC06061; GA AV ČR KAN200520801; GA ČR GA203/09/0820; GA MZd NR9138 Institutional research plan: CEZ:AV0Z40550506 Keywords : uracil * thymine Subject RIV: CC - Organic Chemistry Impact factor: 3.219, year: 2009

  7. Characterization of laser-induced plasmas of nucleobases: Uracil and thymine

    International Nuclear Information System (INIS)

    In this work, nanosecond laser ablation plasmas generated at 266 and 1064 nm of the two pyrimidine nucleobases uracil and thymine were characterized using time-of-flight mass spectrometry, optical emission spectroscopy and temporally resolved third harmonic generation of a probe laser. This multiple technique approach provides insight into the role played by the irradiation wavelength on the composition and dynamics of plasma species and on the differences between the laser plasmas of the two nucleobases.

  8. Thymine Photodimers. Two-dimensional NMR and photo-CIDNP studies

    OpenAIRE

    Kemmink, Johan

    1987-01-01

    De erfelijke eigenschappen van levende organismen zijn vastgelegd in DNA molekulen in de vorm van een specifieke volgorde van de basen adenine, cytosine, guanine en thymine. Het essentieel voor de ontwikkeling van levende organisemen, dat de DNA molekulen zeer vaak gedupliceerd kunnen worden zoder dat de vastgelegde code noemenswaardig veranderd. Dit vereist een extreem hoge stabiliteit van het DNA molekuul. In schijnbare tegenspraak hiermee is het feit, dat het DNA wordt blootgesteld aan een...

  9. Production of thymine glycols in DNA by radiation and chemical carcinogens as detected by a monoclonal antibody.

    Science.gov (United States)

    Leadon, S A

    1987-06-01

    In order to understand the role in carcinogenesis of damage indirectly induced by chemical carcinogens, it is important to identify the primary DNA lesions. We have measured the formation and repair of one type of DNA modification, 5,6-dihydroxydihydrothymine (thymine glycol), following exposure of cultured human cells to the carcinogens N-hydroxy-2-naphthylamine or benzo(a)pyrene. The efficiency of production of thymine glycols in DNA by these carcinogens was compared to that by ionizing radiation and ultraviolet light. Thymine glycols were detected using a monoclonal antibody against this product in a sensitive immunoassay. We found that thymine glycols were produced in DNA in a dose dependent manner after exposure to the carcinogens and that their production was reduced if either catalase or superoxide dismutase or both were present at the time of treatment. The efficiency of thymine glycol production following exposure to the chemical carcinogens was greater than that following equi-toxic doses of radiation. Thymine glycols were efficiently removed from the DNA of human cells following treatment with either the chemical carcinogens, ionizing radiation or ultraviolet light. PMID:3477281

  10. 1D self-assembly of chemisorbed thymine on Cu(110) driven by dispersion forces.

    Science.gov (United States)

    Temprano, I; Thomas, G; Haq, S; Dyer, M S; Latter, E G; Darling, G R; Uvdal, P; Raval, R

    2015-03-14

    Adsorption of thymine on a defined Cu(110) surface was studied using reflection-absorption infrared spectroscopy (RAIRS), temperature programmed desorption (TPD), and scanning tunnelling microscopy (STM). In addition, density functional theory (DFT) calculations were undertaken in order to further understand the energetics of adsorption and self-assembly. The combination of RAIRS, TPD, and DFT results indicates that an upright, three-point-bonded adsorption configuration is adopted by the deprotonated thymine at room temperature. DFT calculations show that the upright configuration adopted by individual molecules arises as a direct result of strong O-Cu and N-Cu bonds between the molecule and the surface. STM data reveal that this upright thymine motif self-assembles into 1D chains, which are surprisingly oriented along the open-packed [001] direction of the metal surface and orthogonal to the alignment of the functional groups that are normally implicated in H-bonding interactions. DFT modelling of this system reveals that the molecular organisation is actually driven by dispersion interactions, which cause a slight tilt of the molecule and provide the major driving force for assembly into dimers and 1D chains. The relative orientations and distances of neighbouring molecules are amenable for π-π stacking, suggesting that this is an important contributor in the self-assembly process. PMID:25770505

  11. Isolation and identification of thymine products from DNA γ irradiated in oxygen-free aqueous solutions

    International Nuclear Information System (INIS)

    A solution of Escherichia coli DNA 14CH3 labelled in the thymine moiety was deaerated under vacuum by repeated cycles of freezing and pumping; sample was irradiated in sealed vial by 60Co γ rays with a dose rate of 70 Gy/m at Gy(gy = gray). The resulting polymeric material was separated from the low-molecular weight material by dialysis. Formic acid hydrolysis of the high-molecular weight material yielded thymine, 5,6-dihydrothymine, cis- and trans-5,6-dihydroxythimine, and 5-hydroxy-5,6-dihydrothymine. The initial step of a proposed mechanism involves the formation of hydroxyl radicals, hydrogen atoms, and hydrated electrons, which are formed when water absorbs gamma rays. These species are short-lived and react with DNA. The hydroxyl radicals attack both the C-5 and C-6 sites of the thymine ring; the hydrated electrons react pyrimidine to form ions which then undergo protonation; and hydrogen atoms add preferentially at C-6. The pyrimidine radicals are then able to undergo electron transfer through a dismutation reaction. Solvolytic substitution of the pyrimidic ions and hydrogen atom exchange produce the final reaction products

  12. Spectroscopic assessment of argon gas discharge induced radiolysis of aqueous adenine and thymine

    Energy Technology Data Exchange (ETDEWEB)

    Su Xi [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China); Huang Qing, E-mail: huangq@ipp.ac.cn [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China); Dang Bingrong [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000 (China); Wang Xiangqin; Yu Zengliang [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China)

    2011-12-15

    Ionizing radiation influences life profoundly for it can modify genetic materials. It is a long-standing task to investigate the interaction between energetic particles and DNA together with its components such as nucleotides, nucleosides and bases so as to predict and assess the potential biological effects. In this study, argon gas discharge was employed to produce energetic ions and electrons. The gas discharge caused the radiolysis of aqueous bases and the involved reactions were analyzed by means of spectroscopic tools including UV-vis absorption, fluorescence and Fourier transformation infrared (FTIR) spectroscopy, also assisted by liquid chromatography/mass spectrometry (LC/MS). It was found that the discharge resulted in the adenine-derived lesions such as 4,6-diamino-5-formamidopyrimidine, 8-OH-Ade and 2-OH-Ade in the radiolysis of aqueous adenine, as well as the thymine-derived lesions such as thymine glycol, 5-hydroxy-6-hydrothymine and/or 6-hydroxy-5-hydrothymine, 5-hydroxymethyluracil and 5-formyluracil in the radiolysis of aqueous thymine. The study of radio-sensitivity showed that adenine was more resistant to the discharge. The mechanisms of the involved reactions were studied in detail, confirming that the hydroxyl radical played a dominant role. - Highlights: > Effective new way to study radiolysis of bases via a home-made argon discharge apparatus. > Quantitative analysis of base radiolysis employing spectroscopic tools combined with HPLC/MS. > Discovery of different radiolysis effect compared with other forms of ionizing radiations.

  13. Spectroscopic assessment of argon gas discharge induced radiolysis of aqueous adenine and thymine

    International Nuclear Information System (INIS)

    Ionizing radiation influences life profoundly for it can modify genetic materials. It is a long-standing task to investigate the interaction between energetic particles and DNA together with its components such as nucleotides, nucleosides and bases so as to predict and assess the potential biological effects. In this study, argon gas discharge was employed to produce energetic ions and electrons. The gas discharge caused the radiolysis of aqueous bases and the involved reactions were analyzed by means of spectroscopic tools including UV-vis absorption, fluorescence and Fourier transformation infrared (FTIR) spectroscopy, also assisted by liquid chromatography/mass spectrometry (LC/MS). It was found that the discharge resulted in the adenine-derived lesions such as 4,6-diamino-5-formamidopyrimidine, 8-OH-Ade and 2-OH-Ade in the radiolysis of aqueous adenine, as well as the thymine-derived lesions such as thymine glycol, 5-hydroxy-6-hydrothymine and/or 6-hydroxy-5-hydrothymine, 5-hydroxymethyluracil and 5-formyluracil in the radiolysis of aqueous thymine. The study of radio-sensitivity showed that adenine was more resistant to the discharge. The mechanisms of the involved reactions were studied in detail, confirming that the hydroxyl radical played a dominant role. - Highlights: → Effective new way to study radiolysis of bases via a home-made argon discharge apparatus. → Quantitative analysis of base radiolysis employing spectroscopic tools combined with HPLC/MS. Discovery of different radiolysis effect compared with other forms of ionizing radiations.

  14. Association of thymine glycol lesioned DNA with repair enzyme endonuclease III-molecular dynamics study

    International Nuclear Information System (INIS)

    The 2 nanoseconds molecular dynamics (MD) simulation has been performed for the system consisting of repair enzyme and DNA 30-mer with native thymine at position 16 replaced by thymine glycol (TG) solvated in water environment. After 950 picoseconds of MD the enzyme and DNA associated together to form complex that lasted stable up to 2 ns when simulation was terminated. At the contact area of enzyme and DNA there is glutamic acid located as close as 1.6 A to the C3' atom of phosphodiester bond of TG. Initial B-DNA molecule was bent and kinked at the TG during MD. This distortion caused that phosphodiester bond was easier accessible by amino acids of enzyme. The negative value of electrostatic energy (-26 kcal/mol) discriminates TG from nearly neutral native thymine and contributes to the specific recognition of this lesion. Higher number of close water molecules at TG site before formation of complex (compared with other nucleotides) indicates that glycosyl bond of the lesion is easily approached by repair enzyme during scanning of DNA surface and suggests the importance of specific hydration at the lesion during recognition process. (author)

  15. Transport Selectivity of a Diethylene Glycol Dimethacrylate-Based Thymine-imprinted Polymeric Membrane over a Cellulose Support for Nucleic Acid Bases

    Institute of Scientific and Technical Information of China (English)

    QU Xiang-Jin; CHEN Chang-Bao; ZHOU Jie; WU Chun-Hui

    2007-01-01

    The binding mechanism between 9-vinyladenine and pyrimidine base thymine in methanol was studied with UV-visible spectrophotometric method. Based on this study, using thymine as a template molecule, 9-vinyladenine as a novel functional monomer and diethylene glycol dimethacrylate as a new cross-linker, a specific diethylene glycol dimethacrylate-based molecularly imprinted polymeric membrane was prepared over a cellulose support.Then, the resultantly polymeric membrane morphologies were visualized with scanning electron microscopy and its permselectivity was examined using thymine, uracil, cytosine, adenine and guanine as substrates. This result showed that the imprinting polymeric membrane prepared with diethylene glycol dimethacrylate exhibited higher transport capacity for the template molecule thymine and its optimal analog uracil than other nucleic acid bases. The membrane also took on higher permselectivity than the imprinted membrane made with ethylene glycol dimethacrylate as a cross-linker. When a mixture including five nucleic acid bases thymine, uracil, cytosine, adenine and guanine passed through the diethylene glycol dimethacrylate-based thymine-imprinted polymeric membrane,recognition of the membrane for the template molecule thymine and its optimal analog uracil was demonstrated. It was predicted that the molecularly imprinted membrane prepared with diethylene glycol dimethacrylate as cross-linker might be applicable to thymine assay of absolute hydrolysates of DNA or uracil assay of absolute hydrolysates of RNA in biological samples because of its high selectivity for the template molecule thymine and its optimal analog uracil.

  16. Functionalization of single-walled carbon nanotubes with uracil, guanine, thymine and L-alanine

    Science.gov (United States)

    Silambarasan, D.; Iyakutti, K.; Vasu, V.

    2014-06-01

    Experimental investigation of functionalization of oxidized single-walled carbon nanotubes (OSWCNTs) with three nucleic acid bases such as uracil, guanine, thymine and one amino acid, L-alanine is carried out. Initially, the SWCNTs are oxidized by acid treatment. Further, the oxidized SWCNTs are effectively functionalized with aforementioned biological compounds by ultrasonication. The diameter of OSWCNTs has increased after the adsorption of biological compounds. The cumulative Π-Π stacking, hydrogen bond and polar interaction are the key factors to realize the adsorption. The amount of adsorption of each biological compound is estimated. The adsorption of guanine is more among all the four biological compounds.

  17. The effect of pi-stacking, h-bonding, and electrostatic interactions on the ionization energies of nucleic acid bases: adenine-adenine, thymine-thymine and adenine-thymine dimers

    Energy Technology Data Exchange (ETDEWEB)

    Bravaya, Ksenia B.; Kostko, Oleg; Ahmed, Musahid; Krylov, Anna I.

    2009-09-02

    A combined theoretical and experimental study of the ionized dimers of thymine and adenine, TT, AA, and AT, is presented. Adiabatic and vertical ionization energies(IEs) for monomers and dimers as well as thresholds for the appearance of the protonated species are reported and analyzed. Non-covalent interactions stronglyaffect the observed IEs. The magnitude and the nature of the effect is different for different isomers of the dimers. The computations reveal that for TT, the largestchanges in vertical IEs (0.4 eV) occur in asymmetric h-bonded and symmetric pi- stacked isomers, whereas in the lowest-energy symmetric h-bonded dimer the shiftin IEs is much smaller (0.1 eV). The origin of the shift and the character of the ionized states is different in asymmetric h-bonded and symmetric stacked isomers. Inthe former, the initial hole is localized on one of the fragments, and the shift is due to the electrostatic stabilization of the positive charge of the ionized fragment by thedipole moment of the neutral fragment. In the latter, the hole is delocalized, and the change in IE is proportional to the overlap of the fragments' MOs. The shifts in AAare much smaller due to a less effcient overlap and a smaller dipole moment. The ionization of the h-bonded dimers results in barrierless (or nearly barrierless) protontransfer, whereas the pi-stacked dimers relax to structures with the hole stabilized by the delocalization or electrostatic interactions.

  18. Production of thymine glycols in DNA by N-hydroxy-2-naphthylamine as detected by a monoclonal antibody.

    Science.gov (United States)

    Kaneko, M; Leadon, S A

    1986-01-01

    We have quantitated the production of thymine glycols in DNA following treatment of cultured human fibroblasts or DNA in solution with the carcinogen N-hydroxy-2-naphthylamine. Thymine glycols, detected by using a monoclonal antibody specific to this base damage, were produced in DNA in a dose dependent manner both in vitro and in vivo. Exposure of DNA to N-hydroxy-2-naphthylamine in the presence of catalase and superoxide dismutase, which break down hydrogen peroxide and superoxide anions, respectively, inhibited the production of this base damage. Thymine glycols were efficiently removed from DNA in both normal human fibroblasts and in cells from a patient with xeroderma pigmentosum complementation group A, which are deficient in nucleotide excision repair. PMID:3940211

  19. Kinetic observation of rapid electron transfer between thymine and thymidine anion radicals and caffeic acid: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Rapid electron transfer from thymine or thymidine anion radicals to caffeic acid with rate constant of 1 x 109 M-1s-1 was observed by pulse radiolysis, leading to the formation of anion radicals of caffeic acid which is characterized with absorption maximum at 360nm. Caffeic acid has a higher one-electron reduction potential than the target molecule (thymine or thymidine) and acts as a electrophilic protector which prevent the target anion radical from its irreversible protonation at C6 leading to its 5-yl radical via fast electron transfer. The kinetic demonstrations have provided dynamic evidence of charge transfer protection mechanism. (author)

  20. Thymine- and Adenine-Functionalized Polystyrene Form Self-Assembled Structures through Multiple Complementary Hydrogen Bonds

    Directory of Open Access Journals (Sweden)

    Yu-Shian Wu

    2014-06-01

    Full Text Available In this study, we investigated the self-assembly of two homopolymers of the same molecular weight, but containing complementary nucleobases. After employing nitroxide-mediated radical polymerization to synthesize poly(vinylbenzyl chloride, we converted the polymer into poly(vinylbenzyl azide through a reaction with NaN3 and then performed click chemistry with propargyl thymine and propargyl adenine to yield the homopolymers, poly(vinylbenzyl triazolylmethyl methylthymine (PVBT and poly(vinylbenzyl triazolylmethyl methyladenine (PVBA, respectively. This PVBT/PVBA blend system exhibited a single glass transition temperature over the entire range of compositions, indicative of a miscible phase arising from the formation of multiple strong complementary hydrogen bonds between the thymine and adenine groups of PVBT and PVBA, respectively; Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy confirmed the presence of these noncovalent interactions. In addition, dynamic rheology, dynamic light scattering and transmission electron microscopy provided evidence for the formation of supramolecular network structures in these binary PVBT/PVBA blend systems.

  1. A germline polymorphism of thymine DNA glycosylase induces genomic instability and cellular transformation.

    Directory of Open Access Journals (Sweden)

    Ashley Sjolund

    2014-11-01

    Full Text Available Thymine DNA glycosylase (TDG functions in base excision repair, a DNA repair pathway that acts in a lesion-specific manner to correct individual damaged or altered bases. TDG preferentially catalyzes the removal of thymine and uracil paired with guanine, and is also active on 5-fluorouracil (5-FU paired with adenine or guanine. The rs4135113 single nucleotide polymorphism (SNP of TDG is found in 10% of the global population. This coding SNP results in the alteration of Gly199 to Ser. Gly199 is part of a loop responsible for stabilizing the flipped abasic nucleotide in the active site pocket. Biochemical analyses indicate that G199S exhibits tighter binding to both its substrate and abasic product. The persistent accumulation of abasic sites in cells expressing G199S leads to the induction of double-strand breaks (DSBs. Cells expressing the G199S variant also activate a DNA damage response. When expressed in cells, G199S induces genomic instability and cellular transformation. Together, these results suggest that individuals harboring the G199S variant may have increased risk for developing cancer.

  2. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  3. Thermodynamic potential for the abiotic synthesis of Adenine, Cytosine, Guanine, Thymine, Uracil, Ribose, and Deoxyribose in hydrothermal systems

    OpenAIRE

    Larowe, D. E.; Regnier, P.

    2008-01-01

    The thermodynamic potential for the abiotic synthesis of the five common nucleobases (adenine, cytosine, guanine, thymine, and uracil) and two monosaccharides (ribose and deoxyribose) from formaldehyde and hydrogen cyanide has been quantified under temperature, pressure, and bulk composition conditions that are representative of hydrothermal systems. The activities of the precursor molecules (formaldehyde and hydrogen cyanide) required to evaluate the thermodynamics of biomolecule synthesis w...

  4. Bearing structures

    International Nuclear Information System (INIS)

    A hydrostatic bearing for the lower end of the vertical shaft of a sodium pump comprises a support shell encircling the shaft and a bush located between the shell and shaft. Liquid sodium is fed from the pump outlet to the bush/shaft and bush/shell interfaces to provide hydrostatic support. The bush outer surface and the shell inner surface are of complementary part-spherical shape and the bush floats relative to the shaft so that the bush can align itself with the shaft axis. Monitoring of the relative rotational speed of the bush with respect to the shaft (such rotation being induced by the viscous drag forces present) is also performed for the purposes of detecting abnormal operation of the bearing or partial seizure, at least one magnet is rotatable with the bush, and a magnetic sensor provides an output having a frequency related to the speed of the bush. (author)

  5. Radiosensitization of thymine by Fe(III)-1,2 dihydroxyanthraquinone complex in dilute aqueous solution

    International Nuclear Information System (INIS)

    A complex of Fe(III) with 1,2 dihydroxy 9, 10, anthraquinone (DHA) has been prepared. The metal ion forms a 1:3 complex with DHA. The complex is formed due to the dissociation of one proton per ligand bound to the metal ion. The stability constant of the Fe(III) complex is 1.61 x 1032. The complex reduces the catalytic flow of electrons from NADH to molecular O2 through NADH dehydrogenease over DHA. The Fe(III) complex is seen to be an efficient radiosensitizer towards γ-radiation induced degradation of thymine in a nitrous oxide saturated medium. (author). 31 refs., 2 figs., 1 tab

  6. Electronic structure of uracil-like nucleobases adsorbed on Si(001): uracil, thymine and 5-fluorouracil

    Science.gov (United States)

    Molteni, Elena; Onida, Giovanni; Cappellini, Giancarlo

    2016-04-01

    We study the electronic properties of the Si(001):Uracil, Si(001):Thymine, and Si(001):5-Fluorouracil systems, focusing on the Si dimer-bridging configuration with adsorption governed by carbonyl groups. While the overall structural and electronic properties are similar, with small differences due to chemical substitutions, much larger effects on the surface band dispersion and bandgap show up as a function of the molecular orientation with respect to the surface. An off-normal orientation of the molecular planes is favored, showing larger bandgap and lower total energy than the upright position. We also analyze the localization of gap-edge occupied and unoccupied surface states. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjb/e2016-70011-1

  7. Ultrafast dynamics of uracil and thymine studied using a sub-10 fs deep ultraviolet laser.

    Science.gov (United States)

    Xue, Bing; Yabushita, Atsushi; Kobayashi, Takayoshi

    2016-06-22

    Single 9.6 fs deep ultraviolet pulses with a spectral range of 255-290 nm are generated by a chirped-pulse four-wave mixing technique for use as pump and probe pulses. The electronic excited state and vibrational dynamics are simultaneously observed for an aqueous solution of uracil and thymine over the full spectral range using a 128-channel lock-in amplifier detector. Two probe photon energy-dependent lifetimes gradually increasing with the probe photon energy are obtained from the decay dynamics data. Ultrafast decay dynamics through the conical intersection is assigned from the first excited ππ* to the final ground state involving the nπ* states. Vibrational modes of the electronic ground state and excited states can be observed, which are strongly coupled to the decay dynamics of the electronic excited state. PMID:27299165

  8. Role of sugar in controlling reaction pathways: A study with thymine and thymidine

    International Nuclear Information System (INIS)

    Magnetic field effect in conjunction with laser flash photolysis have been used for studying interactions of 9,10-anthraquinone and 2-methyl 1,4-naphthoquinone (menadione) with a DNA base, thymine (Thy) and its nucleoside, thymidine (dThd). Irrespective of medium Thy has been found to support both electron transfer (ET) and hydrogen abstraction with the quinones while dThd has exhibited a complete reluctance towards ET. This unique behavior of dThd has been attributed to a failure in attaining aromaticity by virtue of keto-enol tautomerism upon addition of a sugar moiety. Electron withdrawing effect of sugar unit is also considered responsible for reduction of ET from dThd. Again both Thy and dThd have exhibited hydrogen abstraction in homogeneous medium, which is normally unexpected. The above behaviors of the bases have been explained on the basis of their chemical structures.

  9. Transcriptional regulation of thymine DNA glycosylase (TDG) by the tumor suppressor protein p53.

    Science.gov (United States)

    da Costa, Nathalia Meireles; Hautefeuille, Agnès; Cros, Marie-Pierre; Melendez, Matias Eliseo; Waters, Timothy; Swann, Peter; Hainaut, Pierre; Pinto, Luis Felipe Ribeiro

    2012-12-15

    Thymine DNA glycosylase (TDG) belongs to the superfamily of uracil DNA glycosylases (UDG) and is the first enzyme in the base-excision repair pathway (BER) that removes thymine from G:T mismatches at CpG sites. This glycosylase activity has also been found to be critical for active demethylation of genes involved in embryonic development. Here we show that wild-type p53 transcriptionally regulates TDG expression. Chromatin immunoprecipitation (ChIP) and luciferase assays indicate that wild-type p53 binds to a domain of TDG promoter containing two p53 consensus response elements (p53RE) and activates its transcription. Next, we have used a panel of cell lines with different p53 status to demonstrate that TDG mRNA and protein expression levels are induced in a p53-dependent manner under different conditions. This panel includes isogenic breast and colorectal cancer cell lines with wild-type or inactive p53, esophageal squamous cell carcinoma cell lines lacking p53 or expressing a temperature-sensitive p53 mutant and normal human bronchial epithelial cells. Induction of TDG mRNA expression is accompanied by accumulation of TDG protein in both nucleus and cytoplasm, with nuclear re-localization occurring upon DNA damage in p53-competent, but not -incompetent, cells. These observations suggest a role for p53 activity in TDG nuclear translocation. Overall, our results show that TDG expression is directly regulated by p53, suggesting that loss of p53 function may affect processes mediated by TDG, thus negatively impacting on genetic and epigenetic stability. PMID:23165212

  10. Tooling Converts Stock Bearings To Custom Bearings

    Science.gov (United States)

    Fleenor, E. N., Jr.

    1983-01-01

    Technique for reworking stock bearings saves time and produces helicopter-rotor bearings ground more precisely. Split tapered ring at one end of threaded bolt expands to hold inside of inner race bearing assembly; nut, at other end of bolt, adjusts amount of spring tension. Piece of hardware grasps bearing firmly without interfering with grinding operation. Operation produces bearing of higher quality than commercially available bearings.

  11. Determination of 5-methylcytosine from plant DNA by high-performance liquid chromatography.

    Science.gov (United States)

    Wagner, I; Capesius, I

    1981-06-26

    The relative amounts of the five nucleosides (deoxycytidine, 5-methyldeoxycytidine, deoxyadenosine, deoxyguanosine and thymidine) in the DNA of nine plant species, one plant satellite DNA, and one animal species were determined by high performance liquid chromatography. The method allows the clean separation of the nucleosides from 10 microgram samples with 15 min. The following values for the proportion of methylated cytosines among all cytosines were obtained: Lobularia maritima 18.5%, Nicotiana tabacum 32.6%, Pisum sativum 23.2%, Rhinanthus minor 29.2%, Sinapsis alba 12.2%, Vicia faba 30.5%, Viscum album 23.2%, Cymbidium pumilum 18.8%, Cymbidium pumilum AT-rich satellite DNA 15.8%, Triticum aestivum 22.4%. DNA of an animal, the gerbil, Meriones unguiculatus, had a methylation percentage of 3.1%. An estimate of the GC content based on the buoyant density of DNA tends to be lower than the actual value, an estimate based on the melting temperature tends to be higher. This supports the finding by other authors that DNA methylation decreases the buoyant density and may increase the melting temperature at high m5C concentration. PMID:7272310

  12. Crystal structures of B-DNA dodecamer containing the epigenetic modifications 5-hydroxymethylcytosine or 5-methylcytosine

    Czech Academy of Sciences Publication Activity Database

    Renčiuk, Daniel; Blacque, O.; Vorlíčková, Michaela; Spingler, B.

    2013-01-01

    Roč. 41, č. 21 (2013), s. 9891-9900. ISSN 0305-1048 R&D Projects: GA ČR GAP205/12/0466; GA MŠk(CZ) ED1.1.00/02.0068 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : NUCLEIC-ACID STRUCTURES * CIRCULAR-DICHROISM * DEOXYRIBONUCLEIC-ACID Subject RIV: BO - Biophysics Impact factor: 8.808, year: 2013

  13. Deposition of 5-Methylcytosine on Enhancer RNAs Enables the Coactivator Function of PGC-1α.

    Science.gov (United States)

    Aguilo, Francesca; Li, SiDe; Balasubramaniyan, Natarajan; Sancho, Ana; Benko, Sabina; Zhang, Fan; Vashisht, Ajay; Rengasamy, Madhumitha; Andino, Blanca; Chen, Chih-hung; Zhou, Felix; Qian, Chengmin; Zhou, Ming-Ming; Wohlschlegel, James A; Zhang, Weijia; Suchy, Frederick J; Walsh, Martin J

    2016-01-26

    The Peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) is a transcriptional co-activator that plays a central role in adapted metabolic responses. PGC-1α is dynamically methylated and unmethylated at the residue K779 by the methyltransferase SET7/9 and the Lysine Specific Demethylase 1A (LSD1), respectively. Interactions of methylated PGC-1α[K779me] with the Spt-Ada-Gcn5-acetyltransferase (SAGA) complex, the Mediator members MED1 and MED17, and the NOP2/Sun RNA methytransferase 7 (NSUN7) reinforce transcription, and are concomitant with the m(5)C mark on enhancer RNAs (eRNAs). Consistently, loss of Set7/9 and NSun7 in liver cell model systems resulted in depletion of the PGC-1α target genes Pfkl, Sirt5, Idh3b, and Hmox2, which was accompanied by a decrease in the eRNAs levels associated with these loci. Enrichment of m(5)C within eRNA species coincides with metabolic stress of fasting in vivo. Collectively, these findings illustrate the complex epigenetic circuitry imposed by PGC-1α at the eRNA level to fine-tune energy metabolism. PMID:26774474

  14. Deposition of 5-Methylcytosine on Enhancer RNAs Enables the Coactivator Function of PGC-1α

    Directory of Open Access Journals (Sweden)

    Francesca Aguilo

    2016-01-01

    Full Text Available The Peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α is a transcriptional co-activator that plays a central role in adapted metabolic responses. PGC-1α is dynamically methylated and unmethylated at the residue K779 by the methyltransferase SET7/9 and the Lysine Specific Demethylase 1A (LSD1, respectively. Interactions of methylated PGC-1α[K779me] with the Spt-Ada-Gcn5-acetyltransferase (SAGA complex, the Mediator members MED1 and MED17, and the NOP2/Sun RNA methytransferase 7 (NSUN7 reinforce transcription, and are concomitant with the m5C mark on enhancer RNAs (eRNAs. Consistently, loss of Set7/9 and NSun7 in liver cell model systems resulted in depletion of the PGC-1α target genes Pfkl, Sirt5, Idh3b, and Hmox2, which was accompanied by a decrease in the eRNAs levels associated with these loci. Enrichment of m5C within eRNA species coincides with metabolic stress of fasting in vivo. Collectively, these findings illustrate the complex epigenetic circuitry imposed by PGC-1α at the eRNA level to fine-tune energy metabolism.

  15. Detection and mapping of 5-methylcytosine and 5-hydroxymethylcytosine with nanopore MspA

    OpenAIRE

    Laszlo, Andrew H; Derrington, Ian M.; Brinkerhoff, Henry; Langford, Kyle W.; Nova, Ian C.; Samson, Jenny Mae; Bartlett, Joshua J.; Pavlenok, Mikhail; Gundlach, Jens H.

    2013-01-01

    Cells attach a methyl group (—CH3) to certain cytosines in DNA to control gene expression. These methylation patterns change over time and can be related to cell differentiation and diseases such as cancer. Existing methylation detection techniques are not ideal for clinical use. We pulled single-stranded DNA molecules through the biological pore MspA and found that ion currents passing through the pore reveal the methylation sites with high confidence. Hydroxymethylation, which differs from ...

  16. Glucometer-based quantitative determination of Hg(II) using gold particle encapsulated invertase and strong thymine-Hg(II)-thymine interaction for signal amplification

    International Nuclear Information System (INIS)

    We report on a simple and sensitive protocol for quantitative assay of Hg(II) ions. The process involves the following steps: A thymine (T)-rich single-stranded DNA1 is used to modify the surface of a well of a microplate by the use of biotin-avidin interface chemistry. In parallel, clusters of gold microspheres with a core containing the enzyme invertase were prepared and modified, via thiol chemistry, with a second T-rich oligomer (DNA2). If the gold clusters incorporating invertase and carrying DNA2 are added to the DNA1 immobilized in the wells of the microplate, no interaction will occur and the gold cluster will be removed in the subsequent washing step. If, however, Hg(II) is present in the sample, the DNA on the gold clusters incorporating the enzyme invertase will bind to the DNA in the wells due to the formation of strong T-Hg(II)-T links between the two DNA strands. The encapsulated invertase will not be removed in the following washing step. Sucrose is added in the next step along with invertase which will hydrolyze it to form glucose and fructose. The quantity of glucose formed increases with the quantity of Hg(II) ions present in the sample. The glucose generated is then quantified by using a commercial personal glucometer. Under optimal conditions, the signal for glucose increases with Hg(II) concentration in the range from 0.05 to 80 nM, and the detection limit is as low as 10 pM. The assay has good repeatability and shows an intermediate precision of down to 7.5 %. The method is highly specific for Hg(II) over other metal ions. It was applied to the determination of Hg(II) in naturally contaminated sewage and in spiked samples of drinking water. This approach has a wide scope of application in that it may be extended to numerous other kinds of nanoparticles, oligomer interactions, enzymes and ions. (author)

  17. HCCCH Experiment for Through-Bond Correlation of Thymine Resonances in 13C-Labeled DNA Oligonucleotides

    Science.gov (United States)

    Sklenář, Vladimír.; Masse, James E.; Feigon, Juli

    1999-04-01

    Application of heteronuclear magnetic resonance pulse methods to13C,15N-labeled nucleic acids is important for the accurate structure determination of larger RNA and DNA oligonucleotides and protein-nucleic acid complexes. These methods have been applied primarily to RNA, due to the availability of labeled samples. The two major differences between DNA and RNA are at the C2‧ of the ribose and deoxyribose and the additional methyl group on thymine versus uracil. We have enzymatically synthesized a13C,15N-labeled 32 base DNA oligonucleotide that folds to form an intramolecular triplex. We present two- and three-dimensional versions of a new HCCCH-TOCSY experiment that provides intraresidue correlation between the thymine H6 and methyl resonances via the intervening carbons (H6-C6-C5-Cme-Hme).

  18. Structure and mechanism of hydroxyl radical-induced formation of a DNA-protein cross-link involving thymine and lysine in nucleohistone

    International Nuclear Information System (INIS)

    Hydroxyl radical-induced formation of a DNA-protein cross-link involving thymine and lysine in calf thymus nucleohistone in vitro is reported. Basic amino acids such as lysine constitute a very high proportion of the amino acids of histones, and help histones to bind to DNA in chromatin. For this reason, basic amino acids are likely to participate in DNA-protein cross-linking. For identification of the thymine-lysine cross-link in nucleohistone, hydroxyl radical-induced cross-linking of thymine to lysine was investigated first using a model system, i.e., an aqueous mixture of thymine and lysine. Hydroxyl radicals were generated by exposure of this mixture to ionizing radiation after N2O saturation. The technique of gas chromatography-mass spectrometry was used to analyze the samples for possible cross-links. One thymine-lysine cross-link was found and its structure was elucidated. Using gas chromatography-mass spectrometry with selected-ion monitoring, this thymine-lysine cross-link was identified in acidic hydrolysates of calf thymus nucleohistone gamma-irradiated in N2O-saturated aqueous solution. The yield of this DNA-protein cross-link was also measured and found to be a linear function of radiation dose between 15 and 200 Gy. This yield amounted to 0.0085 mumol/J. Possible mechanisms for the formation of this DNA-protein cross-link in nucleohistone were proposed

  19. Kinetics and binding of the thymine-DNA mismatch glycosylase, Mig-Mth, with mismatch-containing DNA substrates.

    Science.gov (United States)

    Begley, Thomas J; Haas, Brian J; Morales, Juan C; Kool, Eric T; Cunningham, Richard P

    2003-01-01

    We have examined the removal of thymine residues from T-G mismatches in DNA by the thymine-DNA mismatch glycosylase from Methanobacterium thermoautrophicum (Mig-Mth), within the context of the base excision repair (BER) pathway, to investigate why this glycosylase has such low activity in vitro. Using single-turnover kinetics and steady-state kinetics, we calculated the catalytic and product dissociation rate constants for Mig-Mth, and determined that Mig-Mth is inhibited by product apyrimidinic (AP) sites in DNA. Electrophoretic mobility shift assays (EMSA) provide evidence that the specificity of product binding is dependent upon the base opposite the AP site. The binding of Mig-Mth to DNA containing the non-cleavable substrate analogue difluorotoluene (F) was also analyzed to determine the effect of the opposite base on Mig-Mth binding specificity for substrate-like duplex DNA. The results of these experiments support the idea that opposite strand interactions play roles in determining substrate specificity. Endonuclease IV, which cleaves AP sites in the next step of the BER pathway, was used to analyze the effect of product removal on the overall rate of thymine hydrolysis by Mig-Mth. Our results support the hypothesis that endonuclease IV increases the apparent activity of Mig-Mth significantly under steady-state conditions by preventing reassociation of enzyme to product. PMID:12509271

  20. A novel monofunctional DNA glycosylase activity against thymine glycol in mouse cell nuclei

    International Nuclear Information System (INIS)

    Reactive oxygen species continuously oxidize DNA bases and threaten the genetic integrity. Thymine glycol (TG), one of the representative oxidized products, is repaired mainly by base excision repair (BER). In Escherichia coli, endonuclease III (Nth) and endonuclease VIII (Nei) are known to actively remove TG from DNA, and the homologs are well conserved in various organisms. These are bifunctional glycosylases, also associated with apurinic/apyrimidinic (AP) lyase activity. In the present study, a monofunctional TG-DNA glycosylase activity is shown to be one of the predominant nuclear activities present in some mouse tissues. By combining hypertonic extraction and column chromatography, we successfully separated the novel activity from majority of the bifunctional activities. Since it has been reported that mNTH1 may not be a dominant nuclear activity, the monofunctional glycosylase activity, together with mNEIL1, may be the major TG-DNA glycosylases in the mouse nucleus. The optimal reaction conditions for the monofunctional activity were found to be pH 7-8 and 100-150 mM KC1, and the activity was resistant to 20 mM EDTA. High monofunctional activity was detected in the spleen and stomach, while the level was significantly lower in the liver, suggesting that the contribution of the monofunctional activity is variable among organs. (author)

  1. Damage mechanism of hydroxyl radicals toward adenine—thymine base pair

    International Nuclear Information System (INIS)

    The adenine—thymine base pair was studied in the presence of hydroxyl radicals in order to probe the hydrogen bond effect. The results show that the hydrogen bonds have little effect on the hydroxylation and dehydrogenation happened at the sites, which are not involved in a hydrogen bond, while at the sites involved in hydrogen bond formation in the base pair, the reaction becomes more difficult, both in view of the free energy barrier and the exothermicity. With a 6–311++G(d,p) level of description, both B3LYP and MP2 methods confirm that the C8 site of isolated adenine has the highest possibility to form covalent bond with the hydroxyl radicals, though with different energetics: B3LYP predicts a barrierless pathway, while MP2 finds a transition state with an energy of 106.1 kJ/mol. For the dehydrogenation reactions, B3LYP method predicts that the free energy barrier increases in the order of HN9 < HN61 < HN62 < H2 < H8. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Theoretical and Experimental Photoelectron Spectroscopy Characterization of the Ground State of Thymine Cation.

    Science.gov (United States)

    Majdi, Youssef; Hochlaf, Majdi; Pan, Yi; Lau, Kai-Chung; Poisson, Lionel; Garcia, Gustavo A; Nahon, Laurent; Al-Mogren, Muneerah Mogren; Schwell, Martin

    2015-06-11

    We report on the vibronic structure of the ground state X̃(2)A″ of the thymine cation, which has been measured using a threshold photoelectron photoion coincidence technique and vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum, recorded over ∼0.7 eV above the ionization potential (i.e., covering the whole ground state of the cation) shows rich vibrational structure that has been assigned with the help of calculated anharmonic modes of the ground electronic cation state at the PBE0/aug-cc-pVDZ level of theory. The adiabatic ionization energy has been experimentally determined as AIE = 8.913 ± 0.005 eV, in very good agreement with previous high resolution results. The corresponding theoretical value of AIE = 8.917 eV has been calculated in this work with the explicitly correlated method/basis set (R)CCSD(T)-F12/cc-pVTZ-F12, which validates the theoretical approach and benchmarks its accuracy for future studies of medium-sized biological molecules. PMID:25539153

  3. Interactions of Some Divalent Metal Ions with Thymine and Uracil Thiosemicarbazide Derivatives.

    Science.gov (United States)

    Hammud, Hassan H; El-Dakdouki, Mohammad H; Sonji, Nada; Sonji, Ghassan; Bouhadir, Kamal H

    2016-05-01

    The study of interactions between metal ions and nucleobases, nucleosides, nucleotides, or nucleic acids has become an active research area in chemical, biological, and therapeutic fields. In this respect, the coordination behavior of nucleobase derivatives to transition metals was studied in order to get a better understanding about DNA-metal interactions in in vitro and in vivo systems. Two nucleobase derivatives, 3-benzoyl-1-[3-(thymine-1-yl)propamido]thiourea and 3-benzoyl-1-[3-(uracil-1-yl)propamido]thiourea, were synthesized and their dissociation constants were determined at different temperatures and 0.3 ionic strength. Potentiometric studies were carried out on the interaction of the derivatives towards some divalent metals in 50% v/v ethanol-water containing 0.3 mol.dm(-3) KCl, at five different temperatures. The formation constants of the metal complexes for both ligands follow the order: Cu(2+) > Ni(2+) > Co(2+) > Zn(2+) > Pb(2+) > Cd(2+) > Mn(2+). The thermodynamic parameters were estimated; the complexation process has been found to be spontaneous, exothermic, and entropically favorable. PMID:27049340

  4. Base excision by thymine DNA glycosylase mediates DNA-directed cytotoxicity of 5-fluorouracil.

    Directory of Open Access Journals (Sweden)

    Christophe Kunz

    2009-04-01

    Full Text Available 5-Fluorouracil (5-FU, a chemotherapeutic drug commonly used in cancer treatment, imbalances nucleotide pools, thereby favoring misincorporation of uracil and 5-FU into genomic DNA. The processing of these bases by DNA repair activities was proposed to cause DNA-directed cytotoxicity, but the underlying mechanisms have not been resolved. In this study, we investigated a possible role of thymine DNA glycosylase (TDG, one of four mammalian uracil DNA glycosylases (UDGs, in the cellular response to 5-FU. Using genetic and biochemical tools, we found that inactivation of TDG significantly increases resistance of both mouse and human cancer cells towards 5-FU. We show that excision of DNA-incorporated 5-FU by TDG generates persistent DNA strand breaks, delays S-phase progression, and activates DNA damage signaling, and that the repair of 5-FU-induced DNA strand breaks is more efficient in the absence of TDG. Hence, excision of 5-FU by TDG, but not by other UDGs (UNG2 and SMUG1, prevents efficient downstream processing of the repair intermediate, thereby mediating DNA-directed cytotoxicity. The status of TDG expression in a cancer is therefore likely to determine its response to 5-FU-based chemotherapy.

  5. Structures in dissociative electron attachment cross-sections in thymine, uracil and halo-uracils

    International Nuclear Information System (INIS)

    The low energy parts (0 - 3 eV) of the dissociative electron attachment (DEA) cross-sections in uracil, thymine, and the halo-uracils 5-BrU, 5-ClU, 6-ClU, 5-FU, have been revisited with an improved energy resolution, focussing onto the puzzling structures observed on most cross-sections of the various anions fragments versus electron energy. The elastic electron scattering cross-sections near zero energy have also been recorded. In most cases they present a few features (cusps) related to the low energy peaks found in DEA cross-sections. Substantial differences are found in the detailed spectra of the fragments produced in 5-ClU and 6-ClU. Several interpretations already proposed to explain the previous observations, in terms of different thresholds and/or contributions of vibrational Feshbach resonances, and their limits, are discussed in the light of our new results. We expect that our more detailed results will stimulate theoretical work for a better understanding of the features observed. (authors)

  6. Restoration of bearings

    Science.gov (United States)

    Parker, R. J.; Zaretsky, E. V.; Hanau, H.

    1977-01-01

    Process consisting of grinding raceways to oversize but original quality condition and installing new oversize balls or bearings restores wornout ball and roller bearings to original quality, thereby doubling their operating life. Evaluations reveal process results in restoration of 90% of replaced bearings at less than 50% of new-bearing costs.

  7. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F.

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  8. Enzymatic synthesis of DNA strands containing α-L-LNA (α-L-configured locked nucleic acid) thymine nucleotides

    DEFF Research Database (Denmark)

    Højland, Torben; Veedu, Rakesh N; Vester, Birte;

    2012-01-01

    We describe the first enzymatic incorporation of an α-L-LNA nucleotide into an oligonucleotide. It was found that the 5'-triphosphate of α-L-LNA is a substrate for the DNA polymerases KOD, 9°N(m), Phusion and HIV RT. Three dispersed α-L-LNA thymine nucleotides can be incorporated into DNA strands...... by all four polymerases, but they were unable to perform consecutive incorporations of α-L-LNA nucleotides. In addition it was found that primer extension can be achieved using templates containing one α-L-LNA nucleotide....

  9. Enzymatic synthesis of DNA strands containing α-L-LNA (α-L-configured locked nucleic acid) thymine nucleotides.

    Science.gov (United States)

    Højland, Torben; Veedu, Rakesh N; Vester, Birte; Wengel, Jesper

    2012-01-01

    We describe the first enzymatic incorporation of an α-L-LNA nucleotide into an oligonucleotide. It was found that the 5'-triphosphate of α-L-LNA is a substrate for the DNA polymerases KOD, 9°N(m), Phusion and HIV RT. Three dispersed α-L-LNA thymine nucleotides can be incorporated into DNA strands by all four polymerases, but they were unable to perform consecutive incorporations of α-L-LNA nucleotides. In addition it was found that primer extension can be achieved using templates containing one α-L-LNA nucleotide. PMID:22679529

  10. Base residue release from 3H-thymine labeled DNA in irradiated E. coli under conditions of enzyme inhibition

    International Nuclear Information System (INIS)

    E. coli C and E. coli K12 cells were incorporated with (3H-C-6)-thymine, irradiated with 60Co-gamma rays, and then variously treated with EDTA and lysed with sodium lauryl sulfate. The 3H-material released from DNA was then measured by Sephadex G-10 gel filtration. Because the focus of this work was the examination of the radiolytic lesions within the DNA, an attempt was made to exclude enzymatic contributions to in vivo product yields from these cells which were irradiated in the presence and absence of O2

  11. Maintenance Free Bearings

    OpenAIRE

    S. M. Muzakkir & Harish Hirani

    2015-01-01

    In the present research work the need of a Maintenance Free Bearings (MFB) is established. The paper presents preliminary friction calculations to highlight the ways to achieve maintenance free bearings. The existing technologies of well established maintenance free bearings are described. The hybridization of bearing technologies to achieve low cost maintenance free bearings has been exemplified. Finally a combination of passive magnetic repulsion and hydrodynamics ha...

  12. Optimization of Environmentally Benign Polymers Based on Thymine and Polyvinyl Sulfonate Using Plackett-Burman Design and Surface Response

    Directory of Open Access Journals (Sweden)

    Julieta Ledesma

    2013-01-01

    Full Text Available Traditional approaches to the development of integrated circuits involve the use and/or manufacture of toxic materials that have a potential environmental impact. An extensive research has been done to design environmentally benign synthetic polymers containing nucleic acid bases, which can be used to enhance the photoresistor technologies. Water soluble, environmentally benign photopolymers of 1-(4-vinylbenzyl thymine (VBT and vinylphenyl sufonate (VPS undergo a photodimerization reaction when exposed to low levels of ultraviolet irradiation leading to an immobilization of the copolymer on a variety of substrates. Plackett-Burman design (PBD and central composite design (CCD were applied to identify the significant factors influencing the polymer crosslinking and dye adsorption processes, which are relevant in the fabrication of copolymer films for potential photoresist use. The PBD results assigned a maximum absorption signal of 0.67, while optimal conditions obtained in this experiment following the CCD method predictions provided a response of 0.83 ± 0.03, being a solid foundation for further use of this methodology in the production of potential photoresistors. The pH effect was relevant for low concentrations but not significant for higher concentrations. To the best of our knowledge, this was the first report applying statistical experimental designs to optimize the crosslinking of thymine-based polymers.

  13. Hg(2+) detection using a phosphorothioate RNA probe adsorbed on graphene oxide and a comparison with thymine-rich DNA.

    Science.gov (United States)

    Huang, Po-Jung Jimmy; van Ballegooie, Courtney; Liu, Juewen

    2016-06-01

    Mercury is a highly toxic heavy metal and many DNA-based biosensors have been recently developed for Hg(2+) detection in water. Among them, thymine-rich DNA is the most commonly used for designing Hg(2+) sensors. However, the thymine-Hg(2+) interaction is strongly affected by the buffer conditions. We recently reported a molecular beacon containing phosphorothioate (PS)-modified RNA linkages that can be cleaved by Hg(2+). In this work, the fluorescence quenching and DNA adsorption properties of nano-sized graphene oxide (NGO) were used to develop a new sensor using the PS-RNA chemistry. Three DNA probes, containing one, three and five PS-RNA linkages, respectively, were tested. Finally, a fluorophore-labeled poly-A DNA with five PS-RNA linkages was selected and adsorbed by NGO. In the presence of Hg(2+), the fluorophore was released from NGO due to the cleavage reaction, resulting in a fluorescence enhancement. This sensor is highly selective for Hg(2+) with a detection limit of 8.5 nM Hg(2+). For comparison, a fluorophore-labeled poly-T DNA was also tested, which responded to Hg(2+) more slowly and was inhibited by high NaCl concentrations, while the PS-RNA probe was more tolerant to different buffer conditions. This work indicates a new method for interfacing DNA with NGO for Hg(2+) detection. PMID:26580137

  14. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...

  15. The sensitivity of Mycoplasma mycoides var. capri cells to γ-radiation after growth in a medium containing the thymine analogue 5-vinyluracil

    International Nuclear Information System (INIS)

    Cells of the bacterium Mycoplasma mycoides var. capri grown in a medium containing the potential radiation-sensitive thymine analogue 5-vinyluracil show a 3-fold increase in sensitivity towards irradiation of a dose of 15 krads of γ-rays. (author)

  16. Reduced graphene oxide conjugate thymine as a new probe for ultrasensitive and selective fluorometric determination of mercury(II) ions

    International Nuclear Information System (INIS)

    We report on a highly sensitive and remarkably selective fluorometric assay for mercury(II) ion. It is based on the formation of a complex between thymine (T) and Hg(II) to form the [Hg(T)2(H2O)2]n complex on the surface of reduced graphene oxide (rGO). This causes the fluorescence emission of rGO (peaking at 550 nm) to be quenched. Under optimal conditions, quenching is selective and fluorescence intensity is linearly related to the concentration of Hg(II) in the range between 100 and 700 nM. The limit of detection is 5 nM. In addition to its sensitivity and selectivity, the method is simple and direct. (author)

  17. 99mTc-thymine scintigraphy may be a promising method in the diagnosis of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Monica Pires; Souza, Sergio Augusto Lopes de; Lopes, Flavia Paiva Proenca Lobo; Rosado-de-Castro, Paulo Henrique; Fonseca, Lea Mirian Barbosa da; Gutfilen, Bianca [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Medicina. Hospital Universitario Clementino Fraga Filho, Departamento de Radiologia

    2013-05-01

    Objective: Mammography has been established as the gold standard for the detection of breast cancer, and imaging techniques such as ultrasonography, magnetic resonance imaging, scintigraphy and positron emission tomography may be useful to improve its sensitivity and specificity. The objective of this study with breast scintigraphy was to evaluate the uptake of {sup 99m}Tc-thymine in mammary lesions. Methods: A total of 45 patients were included in this study. Thirty-three patients (73%) were subjected to surgery or percutaneous biopsy, providing histopathological data. The other 12 patients who remained under surveillance received clinical examinations and biannual mammography with a normal follow-up of at least three years, the data from which were used for comparison with the scintimammography results. Results: The majority of patients (64.4%) had clinically impalpable lesions with a mammogram diagnosis of microcalcifications, impalpable nodules, or focal asymmetry. Of the studied lesions, 87% were smaller or equal to 20 mm in diameter, and 22% had malignant histopathological findings. Scintigraphy with {sup 99m}Tc-thymine had a sensitivity of 70%, a specificity of 85.7%, positive and negative predictive values of 58.3% and 90.9%, respectively, and an accuracy of 82.2%. Conclusions: The results of this study are consistent with those previously reported by other authors. The good specificity and high negative predictive value of this technique and the absence of uptake in the heart indicate that it may be a promising complementary method in clinical practice and that it may contribute to reducing unnecessary benign biopsies. (author)

  18. Cleavage of thymine N3-H bonds by low-energy electrons attached to base π* orbitals

    International Nuclear Information System (INIS)

    In this work, we extend our earlier studies on single strand break (SSB) formation in DNA to consider the possibility of cleaving a thymine N3-H bond to generate a nitrogen-centered anion and a hydrogen radical which might proceed to induce further bond cleavages. In earlier studies, we considered SSBs induced by low-energy electrons that attach to DNA bases' π* orbitals or to phosphate P=O π* orbitals to cleave sugar-phosphate C-O bonds or base-sugar N1-C bonds. We also studied the effects of base π-stacking on the rates of such bond cleavages. To date, our results suggest that sugar-phosphate C-O bonds have the lowest barriers to cleavage, that attachment of electrons with energies below 2 eV most likely occurs at the base π* orbitals, that electrons with energy above 2 eV can also attach to phosphate P=O π* orbitals, and that base π stacking has a modest but slowing effect on the rates of SSB formation. However, we had not yet examined the possibility that base N3-H bonds could rupture subsequent to base π* orbital capture. In the present work, the latter possibility is considered and it is found that the barrier to cleavage of the N3-H bond in thymine is considerably higher than for cleaving sugar-phosphate C-O bonds, so our prediction that SSB formation is dominated by C-O bond cleavage remains intact

  19. Bear Spray Safety Program

    Science.gov (United States)

    Blome, C.D.; Kuzniar, R.L.

    2009-01-01

    A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

  20. Optimal Synchronizability of Bearings

    OpenAIRE

    Araújo, N. A. M.; Seybold, H.; Baram, R. M.; Herrmann, H. J.; Andrade, J. S.

    2013-01-01

    Bearings are mechanical dissipative systems that, when perturbed, relax toward a synchronized (bearing) state. Here we find that bearings can be perceived as physical realizations of complex networks of oscillators with asymmetrically weighted couplings. Accordingly, these networks can exhibit optimal synchronization properties through fine tuning of the local interaction strength as a function of node degree [Motter, Zhou, and Kurths, Phys. Rev. E 71, 016116 (2005)]. We show that, in analogy...

  1. Bearing restoration by grinding

    Science.gov (United States)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  2. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager;

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

  3. Bearing fatigue investigation 3

    Science.gov (United States)

    Nahm, A. H.; Bamberger, E. N.; Signer, H. R.

    1982-01-01

    The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects.

  4. Arcturus and the Bears

    Science.gov (United States)

    Antonello, E.

    2009-08-01

    Arcturus is the brightest star in Bootes. The ancient Greek name Arktouros means Bear Guard. The star, however, is not close to Ursa Maior (Big She-Bear) and Ursa Minor (Little She-Bear), as the name would suggest. This curious discrepancy could be explained by the star proper motion, assuming the name Bear Guard is a remote cultural heritage. The proper motion analysis could allow us to get an insight also into an ancient myth regarding Ursa Maior. Though we cannot explain scientifically such a myth, some interesting suggestions can be obtained about its possible origin, in the context of the present knowledge of the importance of the cult of the bear both during the Palaeolithic times and for several primitive populations of modern times, as shown by the ethnological studies.

  5. Zn(2+)-cyclen-based complex enable a selective detection of single-stranded thymine-rich DNA in aqueous buffer.

    Science.gov (United States)

    Zhu, Zece; Wang, Sheng; Wei, Danqing; Yang, Chuluo

    2016-11-15

    It is a big challenge to develop fluorescent probes for selective detection of DNA with specific sequences in aqueous buffers. We report a new tetraphenylethene-based Zn(2+)-cyclen complex (TPECyZn), and a chemo-sensing ensemble of the Zn complex with phenol red. TPECyZn showed significant fluorescence enhancement upon binding to thymine-rich DNA in HEPES buffers. But its selectivity was not high enough to eliminate the interference from some random DNA. By constructing the chemo-sensing ensemble of TPECyZn with phenol red, the background fluorescence was eliminated due to the energy transfer from TPECyZn to phenol red. Moreover, this chemo-sensing ensemble revealed high selectivity in detecting thymine-rich single-stranded DNA over other DNA in aqueous buffer. It can detect poly deoxythymidylic acid sequence as short as 2 nt. This detection in aqueous media makes this probe feasible in real application. PMID:27288711

  6. Fundamental studies on the radiation chemical dose-response with use of thymine. Is activation of the surface between radiation biology and radiation chemistry possible?

    International Nuclear Information System (INIS)

    The review described the importance and difficulty of radiation chemical assessment of dose-response. The assessment has the tasks of the unit, low dose region evaluation and direct/indirect effects in biology. The authors' vacuum evaporated thymine for G-value determination is appropriate for XANES (X-ray absorption near edge structures) measurement with monochromic ultrasoft X-rays (-550 eV photon) generated by SPring-8. However, the data of yielded thymine derivatives as well as those yielded after 60Co γ-ray (1.5 MeV photon) irradiation are not suitable for direct application in DNA damage evaluation of living cells due to trans-scientific uncertainty. Efforts are required for reducing the uncertainty present in dose-response assessment. (K.H.)

  7. Detection of single base mismatches of thymine and cytosine residues by potassium permanganate and hydroxylamine in the presence of tetralkylammonium salts.

    OpenAIRE

    Gogos, J.A.; Karayiorgou, M; Aburatani, H; Kafatos, F C

    1990-01-01

    In the presence of tetramethylammonium chloride, potassium permanganate specifically modifies mismatched thymines. Similarly, the modification of mismatched cytosines by hydroxylamine was enhanced by tetraethylammonium chloride. Modification followed by piperidine cleavage permits specific identification of the T and C mismatches and by extension, when the opposite DNA strand is analyzed, of A and G mismatches as well. These reactions can be performed conveniently with DNA immobilized on Hybo...

  8. Solvent effects on the ultrafast nonradiative deactivation mechanisms of thymine in aqueous solution: Excited-state QM/MM molecular dynamics simulations

    International Nuclear Information System (INIS)

    On-the-fly excited-state quantum mechanics/molecular mechanics molecular dynamics (QM/MM-MD) simulations of thymine in aqueous solution are performed to investigate the role of solvent water molecules on the nonradiative deactivation process. The complete active space second-order perturbation theory (CASPT2) method is employed for a thymine molecule as the QM part in order to provide a reliable description of the excited-state potential energies. It is found that, in addition to the previously reported deactivation pathway involving the twisting of the C-C double bond in the pyrimidine ring, another efficient deactivation pathway leading to conical intersections that accompanies the out-of-plane displacement of the carbonyl group is observed in aqueous solution. Decay through this pathway is not observed in the gas phase simulations, and our analysis indicates that the hydrogen bonds with solvent water molecules play a key role in stabilizing the potential energies of thymine in this additional decay pathway

  9. Kinetics of in vitro and in vivo dimerisation of thymines in the DNA of plant seedlings and excision of dimers from DNA

    International Nuclear Information System (INIS)

    The conditions of a chromatographic separation of the products of hydrolysis of irradiated DNA used for estimation of the quantity of thymine dimers in acid hydrolysates of polymeric DNA were studied. Using the modified methods of paper chromatography, we studied the kinetics of in vitro and in vivo thymine dimerisation in the DNA of grass pea (Lathyrus sativa L.). The germs isolated from the dry seeds of grass pea were soaked and left for 3 - 5 days in the dark in sterile Petri dishes containing WHITE's medium with 2-C14-thymidine. After UV-irradiation the seedlings were immediately frozen with liquid nitrogen. DNA was isolated according to the modified method of MARMUR and hydrolysed with formic acid. It has been shown that after in vivo irradiation of seedlings the amount of thymine dimers, when the curves dose-effect reach a saturation level, was twice lower than that in the in vitro irradiated DNA. During a 6 hours incubation of UV-irradiated seedlings nearly 30% of pyrimidine dimers were excised from the DNA. (author)

  10. Rapid photometric detection of thymine residues partially flipped out of double helix as a method for direct scanning of point mutations and apurinic DNA sites.

    Science.gov (United States)

    Logvina, N A; Yakubovskaya, M G; Dolinnaya, N G

    2011-02-01

    A spectroscopic assay for detection of extrahelical thymine residues in DNA heteroduplexes under their modification by potassium permanganate has been developed. The assay is based on increase in absorbance at 420 nm due to accumulation of thymidine oxidation intermediates and soluble manganese dioxide. The analysis was carried out using a set of 19-bp DNA duplexes containing unpaired thymidines opposite tetrahydrofuranyl derivatives mimicking a widespread DNA damage (apurinic (AP) sites) and a library of 50-bp DNA duplexes containing all types of base mismatches in different surroundings. The relation between the selectivity of unpaired T oxidation and the thermal stability of DNA double helix was investigated. The method described here was shown to discriminate between DNA duplexes with one or two AP sites and to reveal thymine-containing mismatches and all noncanonical base pairs in AT-surroundings. Comparative results of CCM analysis and the rapid photometric assay for mismatch detection are demonstrated for the first time in the same model system. The chemical reactivity of target thymines was shown to correlate with local disturbance of double helix at the mismatch site. As the spectroscopic assay does not require the DNA cleavage reaction and gel electrophoresis, it can be easily automated and used for primary screening of somatic mutations. PMID:21568858

  11. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  12. DNA methylation patterns of candidate genes regulated by thymine DNA glycosylase in patients with TP53 germline mutations

    International Nuclear Information System (INIS)

    Li-Fraumeni syndrome (LFS) is a rare, autosomal dominant, hereditary cancer predisposition disorder. In Brazil, the p.R337H TP53 founder mutation causes the variant form of LFS, Li-Fraumeni-like syndrome. The occurrence of cancer and age of disease onset are known to vary, even in patients carrying the same mutation, and several mechanisms such as genetic and epigenetic alterations may be involved in this variability. However, the extent of involvement of such events has not been clarified. It is well established that p53 regulates several pathways, including the thymine DNA glycosylase (TDG) pathway, which regulates the DNA methylation of several genes. This study aimed to identify the DNA methylation pattern of genes potentially related to the TDG pathway (CDKN2A, FOXA1, HOXD8, OCT4, SOX2, and SOX17) in 30 patients with germline TP53mutations, 10 patients with wild-type TP53, and 10 healthy individuals. We also evaluated TDG expression in patients with adrenocortical tumors (ADR) with and without the p.R337H TP53 mutation. Gene methylation patterns of peripheral blood DNA samples assessed by pyrosequencing revealed no significant differences between the three groups. However, increased TDG expression was observed by quantitative reverse transcription PCR in p.R337H carriers with ADR. Considering the rarity of this phenotype and the relevance of these findings, further studies using a larger sample set are necessary to confirm our results

  13. DNA methylation patterns of candidate genes regulated by thymine DNA glycosylase in patients with TP53 germline mutations

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, F.P. [CIPE, Laboratrio de Oncogentica Molecular, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Kuasne, H. [CIPE, Laboratrio NeoGene, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Departamento de Urologia, Faculdade de Medicina, Universidade Estadual Paulista, Botucatu, SP (Brazil); Marchi, F.A. [CIPE, Laboratrio NeoGene, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Programa Inter-Institucional em Bioinformtica, Instituto de Matemtica e Estatstica, Universidade So Paulo, So Paulo, SP (Brazil); Miranda, P.M. [CIPE, Laboratrio NeoGene, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Rogatto, S.R. [CIPE, Laboratrio NeoGene, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Departamento de Urologia, Faculdade de Medicina, Universidade Estadual Paulista, Botucatu, SP (Brazil); Achatz, M.I. [CIPE, Laboratrio de Oncogentica Molecular, A.C. Camargo Cancer Center, São Paulo, SP (Brazil); Departamento de Oncogentica, A.C. Camargo Cancer Center, So Paulo, SP (Brazil)

    2015-04-28

    Li-Fraumeni syndrome (LFS) is a rare, autosomal dominant, hereditary cancer predisposition disorder. In Brazil, the p.R337H TP53 founder mutation causes the variant form of LFS, Li-Fraumeni-like syndrome. The occurrence of cancer and age of disease onset are known to vary, even in patients carrying the same mutation, and several mechanisms such as genetic and epigenetic alterations may be involved in this variability. However, the extent of involvement of such events has not been clarified. It is well established that p53 regulates several pathways, including the thymine DNA glycosylase (TDG) pathway, which regulates the DNA methylation of several genes. This study aimed to identify the DNA methylation pattern of genes potentially related to the TDG pathway (CDKN2A, FOXA1, HOXD8, OCT4, SOX2, and SOX17) in 30 patients with germline TP53mutations, 10 patients with wild-type TP53, and 10 healthy individuals. We also evaluated TDG expression in patients with adrenocortical tumors (ADR) with and without the p.R337H TP53 mutation. Gene methylation patterns of peripheral blood DNA samples assessed by pyrosequencing revealed no significant differences between the three groups. However, increased TDG expression was observed by quantitative reverse transcription PCR in p.R337H carriers with ADR. Considering the rarity of this phenotype and the relevance of these findings, further studies using a larger sample set are necessary to confirm our results.

  14. Ab initio study of the structural, tautomeric, pairing, and electronic properties of seleno-derivatives of thymine.

    Science.gov (United States)

    Vázquez-Mayagoitia, Alvaro; Huertas, Oscar; Brancolini, Giorgia; Migliore, Agostino; Sumpter, Bobby G; Orozco, Modesto; Luque, F Javier; Di Felice, Rosa; Fuentes-Cabrera, Miguel

    2009-10-29

    The structural, tautomeric, hydrogen-bonding, stacking, and electronic properties of a seleno-derivative of thymine (T), denoted here as 4SeT and created by replacing O4 in T with Se, are investigated by means of ab initio computational techniques. The structural properties of T and 4SeT are very similar, and the geometrical differences are mainly limited to the adjacent environment of the C-Se bond. The canonical "keto" form is the most stable tautomer, in the gas phase and in aqueous solution, for both T and 4SeT. It is argued that the competition between two opposite trends, i.e., a decrease in the base-pairing ability and an increase of the stacking interaction upon incorporation of 4SeT into a duplex, likely explains the similar experimental melting points of a seleno-derivative duplex (Se-DNA) and its native counterpart. Interestingly, the underlying electronic structure shows that replacement of O4 with Se promotes a reduction in the HOMO-LUMO gap and an increase in interplane coupling, which suggests that Se-DNA could be potentially useful for nanodevice applications. This finding is further supported by the fact that transfer integrals between 4SeT...A stacked base pairs are larger than those determined for similarly stacked natural T...A pairs. PMID:19813710

  15. Ab initio Study of the Structural, Tautomeric, Pairing and Electronic Properties of Seleno-Derivatives of Thymine

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez-Mayagoitia, Alvaro [ORNL; Fuentes-Cabrera, Miguel A [ORNL; Sumpter, Bobby G [ORNL; Luque, Javier [Universitat de Barcelona; Huertas, Oscar [Universitat de Barcelona; Orozco, Modesto [Institut de Recerca Biomedica, Parc Cientific de Barcelona, Barcelona, Spain; Felice, Rosa [INFM-CNR National Research Center S3; Brancolini, Giorgia [ORNL; Migliore, Agostino [University of Pennsylvania

    2009-01-01

    The structural, tautomeric, hydrogen-bonding, stacking and electronic properties of a seleno-derivative of thymine (T), denoted here as 4SeT and created by replacing O4 in T with Se, are investigated by means of ab initio computational techniques. The structural properties of T and 4SeT are very similar and the geometrical differences are mainly limited to the adjacent environment of the C-Se bond. The canonical keto form is the most stable tautomer, in gas phase and in aqueous solution, for both T and 4SeT. It is argued that the competition between two opposite trends, i.e. a decrease in the base-pairing ability and an increase of the stacking interaction upon incorporation of 4SeT into a duplex, likely explains the similar experimental melting points of a seleno-derivative duplex (Se-DNA) and its native counterpart. Interestingly, the underlying electronic structure shows that replacement of O4 with Se promotes a reduction in the HOMO-LUMO gap and an increase in inter-plane coupling, which suggests that Se-DNA could be potentially useful for nanodevice applications. This finding is further supported by the fact that transfer integrals between 4SeT---A stacked base pairs are larger than those determined for similarly stacked natural T---A pairs.

  16. DNA methylation patterns of candidate genes regulated by thymine DNA glycosylase in patients with TP53 germline mutations.

    Science.gov (United States)

    Fortes, F P; Kuasne, H; Marchi, F A; Miranda, P M; Rogatto, S R; Achatz, M I

    2015-07-01

    Li-Fraumeni syndrome (LFS) is a rare, autosomal dominant, hereditary cancer predisposition disorder. In Brazil, the p.R337H TP53 founder mutation causes the variant form of LFS, Li-Fraumeni-like syndrome. The occurrence of cancer and age of disease onset are known to vary, even in patients carrying the same mutation, and several mechanisms such as genetic and epigenetic alterations may be involved in this variability. However, the extent of involvement of such events has not been clarified. It is well established that p53 regulates several pathways, including the thymine DNA glycosylase (TDG) pathway, which regulates the DNA methylation of several genes. This study aimed to identify the DNA methylation pattern of genes potentially related to the TDG pathway (CDKN2A, FOXA1, HOXD8, OCT4, SOX2, and SOX17) in 30 patients with germline TP53 mutations, 10 patients with wild-type TP53, and 10 healthy individuals. We also evaluated TDG expression in patients with adrenocortical tumors (ADR) with and without the p.R337H TP53 mutation. Gene methylation patterns of peripheral blood DNA samples assessed by pyrosequencing revealed no significant differences between the three groups. However, increased TDG expression was observed by quantitative reverse transcription PCR in p.R337H carriers with ADR. Considering the rarity of this phenotype and the relevance of these findings, further studies using a larger sample set are necessary to confirm our results. PMID:25945745

  17. DNA methylation patterns of candidate genes regulated by thymine DNA glycosylase in patients with TP53 germline mutations

    Directory of Open Access Journals (Sweden)

    F.P. Fortes

    2015-07-01

    Full Text Available Li-Fraumeni syndrome (LFS is a rare, autosomal dominant, hereditary cancer predisposition disorder. In Brazil, the p.R337H TP53 founder mutation causes the variant form of LFS, Li-Fraumeni-like syndrome. The occurrence of cancer and age of disease onset are known to vary, even in patients carrying the same mutation, and several mechanisms such as genetic and epigenetic alterations may be involved in this variability. However, the extent of involvement of such events has not been clarified. It is well established that p53 regulates several pathways, including the thymine DNA glycosylase (TDG pathway, which regulates the DNA methylation of several genes. This study aimed to identify the DNA methylation pattern of genes potentially related to the TDG pathway (CDKN2A, FOXA1, HOXD8, OCT4, SOX2, and SOX17 in 30 patients with germline TP53 mutations, 10 patients with wild-type TP53, and 10 healthy individuals. We also evaluated TDG expression in patients with adrenocortical tumors (ADR with and without the p.R337H TP53 mutation. Gene methylation patterns of peripheral blood DNA samples assessed by pyrosequencing revealed no significant differences between the three groups. However, increased TDG expression was observed by quantitative reverse transcription PCR in p.R337H carriers with ADR. Considering the rarity of this phenotype and the relevance of these findings, further studies using a larger sample set are necessary to confirm our results.

  18. Management recommendations: Bear River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document is a review of land management practices at the Bear River Migratory Bird Refuge, by a land use specialist. Recommendations, time frame and additional...

  19. Crystal structures of bis[2-(pyridin-2-ylphenyl-κ2N,C1]rhodium(III complexes containing an acetonitrile or monodentate thyminate(1− ligand

    Directory of Open Access Journals (Sweden)

    Mika Sakate

    2016-04-01

    Full Text Available The crystal structures of bis[2-(pyridin-2-ylphenyl]rhodium(III complexes with the metal in an octahedral coordination containing chloride and acetonitrile ligands, namely (OC-6-42-acetonitrilechloridobis[2-(pyridin-2-ylphenyl-κ2N,C1]rhodium(III, [RhCl(C11H8N2(CH3CN] (1, thyminate(1− and methanol, namely (OC-6-42-methanol(5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ido-κN1bis[2-(pyridin-2-ylphenyl-κ2N,C1]rhodium(III, [Rh(C11H8N2(C5H5N2O2(CH3OH]·CH3OH·0.5H2O (2, and thyminate(1− and ethanol, namely (OC-6-42-ethanol(5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ido-κN1bis[2-(pyridin-2-ylphenyl-κ2N,C1]rhodium(III, [Rh(C11H8N2(C5H5N2O2(C2H5OH]·C2H5OH (3, are reported. The acetonitrile complex, 1, is isostructural with the IrIII analog. In complexes 2 and 3, the monodeprotonated thyminate (Hthym− ligand coordinates to the RhIII atom through the N atom, and the resulting Rh—N(Hthym bond lengths are relatively long [2.261 (2 and 2.252 (2 Å for 2 and 3, respectively] as compared to the Rh—N bonds in the related thyminate complexes. In each of the crystals of 2 and 3, the complexes are linked via a pair of intermolecular N—H...O hydrogen bonds between neighbouring Hthym− ligands, forming an inversion dimer. A strong intramolecular O—H...O hydrogen bond between the thyminate(1− and alcohol ligands in mutually cis positions to each other is also observed.

  20. Cloning, Purification and Initial Characterization of E. coli McrA, a Putative 5-methylcytosine-specific Nuclease

    Energy Technology Data Exchange (ETDEWEB)

    Mulligan,E.; Dunn, J.

    2008-01-01

    Expression strains of Escherichia coli BL21(DE3) overproducing the E. coli m5C McrA restriction protein were produced by cloning the mcrA coding sequence behind a T7 promoter. The recombinant mcrA minus BL21(DE3) host produces active McrA as evidenced by its acquired ability to selectively restrict the growth of T7 phage containing DNA methylated in vitro by HpaII methylase. The mcrA coding region contains several non-optimal E. coli triplets. Addition of the pACYC-RIL tRNA encoding plasmid to the BL21(DE3) host increased the yield of recombinant McrA (rMcrA) upon induction about 5- to 10-fold. McrA protein expressed at 37 C is insoluble but a significant fraction is recovered as soluble protein after autoinduction at 20 C. rMcrA protein, which is predicted to contain a Cys4-Zn2+ finger and a catalytically important histidine triad in its putative nuclease domain, binds to several metal chelate resins without addition of a poly-histidine affinity tag. This feature was used to develop an efficient protocol for the rapid purification of nearly homogeneous rMcrA. The native protein is a dimer with a high a-helical content as measured by circular dichroism analysis. Under all conditions tested purified rMcrA does not have measurable nuclease activity on HpaII methylated (Cm5CGG) DNA, although the purified protein does specifically bind HpaII methylated DNA. These results have implications for understanding the in vivo activity of McrA in 'restricting' m5C-containing DNA and suggest that rMcrA may have utility as a reagent for affinity purification of DNA fragments containing m5C residues.

  1. Cloning, purification and initial characterization of E. coli McrA, a putative 5-methylcytosine-specific nuclease

    OpenAIRE

    Mulligan, Elizabeth A.; Dunn, John J.

    2008-01-01

    Expression strains of Escherichia coli BL21(DE3) overproducing the E. coli m5C McrA restriction protein were produced by cloning the mcrA coding sequence behind a T7 promoter. The recombinant mcrA minus BL21 (DE3) host produces active McrA as evidenced by its acquired ability to selectively restrict the growth of T7 phage containing DNA methylated in vitro by HpaII methylase. The mcrA coding region contains several non-optimal E. coli triplets. Addition of the pACYC-RIL tRNA encoding plasmid ...

  2. Cloning, purification and initial characterization of E. coli McrA, a putative 5-methylcytosine-specific nuclease.

    Science.gov (United States)

    Mulligan, Elizabeth A; Dunn, John J

    2008-11-01

    Expression strains of Escherichia coli BL21(DE3) overproducing the E. coli m(5)C McrA restriction protein were produced by cloning the mcrA coding sequence behind a T7 promoter. The recombinant mcrA minus BL21(DE3) host produces active McrA as evidenced by its acquired ability to selectively restrict the growth of T7 phage containing DNA methylated in vitro by HpaII methylase. The mcrA coding region contains several non-optimal E. coli triplets. Addition of the pACYC-RIL tRNA encoding plasmid to the BL21(DE3) host increased the yield of recombinant McrA (rMcrA) upon induction about 5- to 10-fold. McrA protein expressed at 37 degrees C is insoluble but a significant fraction is recovered as soluble protein after autoinduction at 20 degrees C. rMcrA protein, which is predicted to contain a Cys(4)-Zn(2+) finger and a catalytically important histidine triad in its putative nuclease domain, binds to several metal chelate resins without addition of a poly-histidine affinity tag. This feature was used to develop an efficient protocol for the rapid purification of nearly homogeneous rMcrA. The native protein is a dimer with a high alpha-helical content as measured by circular dichroism analysis. Under all conditions tested purified rMcrA does not have measurable nuclease activity on HpaII methylated (Cm(5)CGG) DNA, although the purified protein does specifically bind HpaII methylated DNA. These results have implications for understanding the in vivo activity of McrA in "restricting" m(5)C-containing DNA and suggest that rMcrA may have utility as a reagent for affinity purification of DNA fragments containing m(5)C residues. PMID:18662788

  3. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  4. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  5. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  6. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  7. Effects of microinjected photoreactivating enzyme on thymine dimer removal and DNA repair synthesis in normal human and xeroderma pigmentosum fibroblasts

    International Nuclear Information System (INIS)

    UV-induced thymine dimers (10 J/m2 of UV-C) were assayed in normal human and xeroderma pigmentosum (XP) fibroblasts with a monoclonal antibody against these dimers and quantitative fluorescence microscopy. In repair-proficient cells dimer-specific immunofluorescence gradually decreased with time, reaching about 25% of the initial fluorescence after 27 h. Rapid disappearance of dimers was observed in cells which had been microinjected with yeast photoreactivating enzyme prior to UV irradiation. This photoreactivation (PHR) was light dependent and (virtually) complete within 15 min of PHR illumination. In general, PHR of dimers strongly reduces UV-induced unscheduled DNA synthesis (UDS). However, when PHR was applied immediately after UV irradiation, UDS remained unchanged initially; the decrease set in only after 30 min. When PHR was performed 2 h after UV exposure, UDS dropped without delay. An explanation for this difference is preferential removal of some type(s) of nondimer lesions, which is responsible for the PHR-resistant UDS immediately following UV irradiation. After the rapid removal of these photoproducts, the bulk of UDS is due to dimer repair. From the rapid effect of dimer removal by PHR on UDS it can be deduced that the excision of dimers up to the repair synthesis step takes considerably less than 30 min. Also in XP fibroblasts of various complementation groups the effect of PHR was investigated. The immunochemical dimer assay showed rapid PHR-dependent removal comparable to that in normal cells. However, the decrease of (residual) UDS due to PHR was absent (in XP-D) or much delayed (in XP-A and -E) compared to normal cells. This supports the idea that in these XP cells preferential repair of nondimer lesions does occur, but at a much lower rate

  8. QM/MM & Monte Carlo simulation of single wall nano tube carbon SWNT (15, 15 binding with thymine dimer

    Directory of Open Access Journals (Sweden)

    Soudeh Safari

    2016-06-01

    Full Text Available In this research, we have studied of thymine dimer binding on the relative energies and dipole moment values and the structural properties of solvent effect (water, methanol and ethanol surrounding single-walled and multi walled carbon nanotube, by using QM/MM simulation, those calculations have carried out with the Gaussian and Hyper Chem package. In this study we investigated the polar solvents effects on SWCNT within the Onsager self - consistent reaction field (SCRF model using a Hartree-Fockmethod and the temperature effect on the stability of SWCNT in various. Because some of the Physicochemical parameters related to structural properties of SWCNT, we used different force fields to determine energy and other types of geometrical parameters, on the particular SWCNT, Because of the differences among force fields, the energy of a molecule calculated using two different force fields will not be the same. It is important to understand the energetic, stability dependent physical properties of armchair (m, n carbon nanotube. In this study, the difference in force fields illustrated by comparing the calculated energies by using force fields such as AMBER ,MM+, and BIO+ .The quantum Mechanics calculations were carried out with the GAUSSIAN 98 program based on density functional theory (DFT at the B1LYP/6-31G* level. Normal Mode Analysis is an important tool for studying the structure and dynamics of Nano-sized systems. The vibrational frequencies obtained can be used to relate observed spectra to the details of the molecular structure, dynamics and other thermodynamic properties.

  9. Glycogen Synthase Kinase-3 regulates IGFBP-1 gene transcription through the Thymine-rich Insulin Response Element

    Directory of Open Access Journals (Sweden)

    Marquez Rodolfo

    2004-09-01

    Full Text Available Abstract Background Hepatic expression of several gene products involved in glucose metabolism, including phosphoenolpyruvate carboxykinase (PEPCK, glucose-6-phosphatase (G6Pase and insulin-like growth factor binding protein-1 (IGFBP-1, is rapidly and completely inhibited by insulin. This inhibition is mediated through the regulation of a DNA element present in each of these gene promoters, that we call the Thymine-rich Insulin Response Element (TIRE. The insulin signalling pathway that results in the inhibition of these gene promoters requires the activation of phosphatidylinositol 3-kinase (PI 3-kinase. However, the molecules that connect PI 3-kinase to these gene promoters are not yet fully defined. Glycogen Synthase Kinase 3 (GSK-3 is inhibited following activation of PI 3-kinase. We have shown previously that inhibitors of GSK-3 reduce the activity of two TIRE-containing gene promoters (PEPCK and G6Pase, whose products are required for gluconeogenesis. Results In this report we demonstrate that in H4IIE-C3 cells, four distinct classes of GSK-3 inhibitor mimic the effect of insulin on a third TIRE-containing gene, IGFBP-1. We identify the TIRE as the minimum requirement for inhibition by these agents, and demonstrate that the target of GSK-3 is unlikely to be the postulated TIRE-binding protein FOXO-1. Importantly, overexpression of GSK-3 in cells reduces the insulin regulation of TIRE activity as well as endogenous IGFBP-1 expression. Conclusions These results implicate GSK-3 as an intermediate in the pathway from the insulin receptor to the TIRE. Indeed, this is the first demonstration of an absolute requirement for GSK-3 inhibition in insulin regulation of gene transcription. These data support the potential use of GSK-3 inhibitors in the treatment of insulin resistant states such as Type 2 diabetes mellitus, but suggest that it will be important to identify all TIRE-containing genes to assess potential side effects of these agents.

  10. Basis set dependence using DFT/B3LYP calculations to model the Raman spectrum of thymine.

    Science.gov (United States)

    Bielecki, Jakub; Lipiec, Ewelina

    2016-02-01

    Raman spectroscopy (including surface enhanced Raman spectroscopy (SERS) and tip enhanced Raman spectroscopy (TERS)) is a highly promising experimental method for investigations of biomolecule damage induced by ionizing radiation. However, proper interpretation of changes in experimental spectra for complex systems is often difficult or impossible, thus Raman spectra calculations based on density functional theory (DFT) provide an invaluable tool as an additional layer of understanding of underlying processes. There are many works that address the problem of basis set dependence for energy and bond length consideration, nevertheless there is still lack of consistent research on basis set influence on Raman spectra intensities for biomolecules. This study fills this gap by investigating of the influence of basis set choice for the interpretation of Raman spectra of the thymine molecule calculated using the DFT/B3LYP framework and comparing these results with experimental spectra. Among 19 selected Pople's basis sets, the best agreement was achieved using 6-31[Formula: see text](d,p), 6-31[Formula: see text](d,p) and 6-11[Formula: see text]G(d,p) sets. Adding diffuse functions or polarized functions for small basis set or use of a medium or large basis set without diffuse or polarized functions is not sufficient to reproduce Raman intensities correctly. The introduction of the diffuse functions ([Formula: see text]) on hydrogen atoms is not necessary for gas phase calculations. This work serves as a benchmark for further research on the interaction of ionizing radiation with DNA molecules by means of ab initio calculations and Raman spectroscopy. Moreover, this work provides a set of new scaling factors for Raman spectra calculation in the framework of DFT/B3LYP method. PMID:26508426

  11. Nonhomologous end joining of complex DNA double-strand breaks with proximal thymine glycol and interplay with base excision repair.

    Science.gov (United States)

    Almohaini, Mohammed; Chalasani, Sri Lakshmi; Bafail, Duaa; Akopiants, Konstantin; Zhou, Tong; Yannone, Steven M; Ramsden, Dale A; Hartman, Matthew C T; Povirk, Lawrence F

    2016-05-01

    DNA double-strand breaks induced by ionizing radiation are often accompanied by ancillary oxidative base damage that may prevent or delay their repair. In order to better define the features that make some DSBs repair-resistant, XLF-dependent nonhomologous end joining of blunt-ended DSB substrates having the oxidatively modified nonplanar base thymine glycol at the first (Tg1), second (Tg2), third (Tg3) or fifth (Tg5) positions from one 3' terminus, was examined in human whole-cell extracts. Tg at the third position had little effect on end-joining even when present on both ends of the break. However, Tg as the terminal or penultimate base was a major barrier to end joining (>10-fold reduction in ligated products) and an absolute barrier when present at both ends. Dideoxy trapping of base excision repair intermediates indicated that Tg was excised from Tg1, Tg2 and Tg3 largely if not exclusively after DSB ligation. However, Tg was rapidly excised from the Tg5 substrate, resulting in a reduced level of DSB ligation, as well as slow concomitant resection of the opposite strand. Ligase reactions containing only purified Ku, XRCC4, ligase IV and XLF showed that ligation of Tg3 and Tg5 was efficient and only partially XLF-dependent, whereas ligation of Tg1 and Tg2 was inefficient and only detectable in the presence of XLF. Overall, the results suggest that promoting ligation of DSBs with proximal base damage may be an important function of XLF, but that Tg can still be a major impediment to repair, being relatively resistant to both trimming and ligation. Moreover, it appears that base excision repair of Tg can sometimes interfere with repair of DSBs that would otherwise be readily rejoined. PMID:27049455

  12. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  13. Blood Pump Bearing System

    Science.gov (United States)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  14. Modular gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  15. XRD and optical microscopic studies of Co(III) complexes containing 5-cyano-6-(4-pyridyl)-2-thiouracil, thymine and adenine bases

    Indian Academy of Sciences (India)

    Lallan Mishra; Brajesh Pathak; R K Mandal

    2001-06-01

    Multifunctional ligand 5-cyano-6-(-4-pyridyl)-2-thiouracil (L) was prepared and allowed to react with trans [Co(en)2Cl2]+Cl– resulting into [Co(en)2LCl]2+.2Cl– which upon further reaction with equimolar ratio of ligand [L] gave the complex [Co(en)2L2]3+.3Cl–. These metal complexes were then separately reacted with thymine and adenine bases. Complexes thus prepared after characterization by their elemental analysis, FAB mass and spectral (IR, 1HNMR, UV-visible) data were studied for their powder X-ray diffraction and optical microscopic characteristics.

  16. Development of Flexible Bearing

    Directory of Open Access Journals (Sweden)

    K.S.Mohanraj

    2014-06-01

    Full Text Available Elastomeric base isolation systems are proven to be effective in reducing seismic forces transmitted to buildings. However, due to their cost, the use of these devices is currently limited to large and expensive buildings. A fiber reinforced elastomeric isolator utilizes fiber fabric, such as carbon fiber, glass fibre, and etc. as the reinforcement material instead of solid steel plates. The fibre fabric reinforcement is extensible in tension and has no flexural rigidity. Elastomers normally used in the isolator are natural rubber; neoprene, butyl rubber and nit rile rubber etc. These devices were fabricated by binding alternating layers of rubber and fibre mesh. The fibre mesh is used to increase the vertical stiffness of the bearings while maintaining low lateral stiffness. Characterizing the behaviour of a fibre reinforced bearing “shape factor” of the bearing, Poisson’s ratio of the elastomeric material and flexibility of the reinforcing sheets and investigate the effect of reinforcement flexibility on compressive behaviour of elastomeric bearings with different geometrical and material properties. Bonding with fibre reinforcements can increase the stiffness of elastic layers only when the elastic layer is compressed.

  17. Flexure Bearing Reduces Startup Friction

    Science.gov (United States)

    Clingman, W. Dean

    1991-01-01

    Design concept for ball bearing incorporates small pieces of shim stock, wire spokes like those in bicycle wheels, or other flexing elements to reduce both stiction and friction slope. In flexure bearing, flexing elements placed between outer race of ball bearing and outer ring. Elements flex when ball bearings encounter small frictional-torque "bumps" or even larger ones when bearing balls encounter buildups of grease on inner or outer race. Flexure of elements reduce high friction slopes of "bumps", helping to keep torque between outer ring and inner race low and more nearly constant. Concept intended for bearings in gimbals on laser and/or antenna mirrors.

  18. Reliability for fluid bearings design

    OpenAIRE

    DIOP, Khadim; CHARKI, Abdérafi; CHAMPMARTIN, Stéphane; AMBARI, Abdelhak

    2013-01-01

    This paper presents a new methodology for evaluating the failure probability of fluid bearings which are sensitive components for the design of machine rotors, mechatronic systems and high precision metrology. The static and dynamic behavior of a fluid bearing depends on several parameters, such as external load, bearing dimensions, supply pressure, quality of the machined surfaces, fluid properties, etc. In this paper, the characteristics of a simple geometry thrust bearing are calculated an...

  19. Reliability of a hydrostatic bearing

    OpenAIRE

    CHARKI, Abderafi; DIOP, Khadim; CHAMPMARTIN, Stéphane; AMBARI, Abdelhak

    2013-01-01

    This paper presents a methodology for evaluating the failure probability of fluid bearings, which are sensitive components for the design of machine rotors, mechatronic systems, and high precision metrology. The static and dynamic behavior of a fluid bearing depends on several parameters, such as external load, bearing dimensions, supply pressure, quality of the machined surfaces, fluid properties, etc. In this paper, the characteristics of a simple geometry hydrostatic bearing are calculated...

  20. Households' Interest-bearing Assets

    OpenAIRE

    Ellis Connolly; Fiona Fleming; Jarkko Jääskelä

    2012-01-01

    Households invest around two-fifths of their financial assets in interest-bearing assets. These assets are predominantly held directly in deposits and also via superannuation and other investment funds. Deposits have grown strongly in recent years, although there has been no growth in interest-bearing securities. Compared with other advanced economies, interest-bearing assets represent a relatively small share of financial assets. For the household sector as a whole, interest-bearing assets a...

  1. γ radiolysis of thymine in oxygen-free aqueous solution in the presence of electron affinic radiosensitizers: identification of stable products

    International Nuclear Information System (INIS)

    Radiosensitizers react with nucleic radicals by addition and by electron transfer reactions. A study has been made of the steady-state γ radiolysis of 1 mM thymine in oxygen-free aqueous solutions containing different classes of radiosensitizing drugs: N-oxyl-free radicals (TAN and TMPN), quinones (menadione and naphthoquinone), nitroheterocyclic compounds (metronidazole and 5-nitro-2-furoic acid) and N-ethylmaleimide. Two classes of thymine degradation products were isolated by thin-layer chromatography and characterized by spectroscopic measurements. The main products, irrespective of radiosensitizers, resulting from oxidation reaction were identified as the cis and trans isomers of 5,6-dihydroxy-5, 6-dihydrothymine, N-pyruvyl-N'-formylurea, 6-hydroxy-5,6-dihydrothymine and 5-hydroxy-5,6-dihydrothymine. In the experimental conditions used only N-oxyls and to a lesser extent NEM reacted with 5-hydroxy-5,6-dihydrothymine-6-yl radical, giving stable covalently-bonded addition products with a high yield. TAN showed a higher binding ability with respect to TMPN, which is in good agreement with the rate-constants previously reported for these bimolecular reactions. (author)

  2. Centrifugally decoupling touchdown bearings

    Science.gov (United States)

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  3. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  4. Rotating plug bearing and seal

    Science.gov (United States)

    Wade, Elman E.

    1977-01-01

    A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

  5. Rotating plug bearing and seal

    International Nuclear Information System (INIS)

    Disclosed is a bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing. 19 claims, 3 figures

  6. ANSWER: A bear paw.

    OpenAIRE

    Ian BICKLE

    2012-01-01

    (Refer to page 186)Answer: Bear Paw sign of Xanthogranulomatous PyelonephritisThe contrast enhanced (portal venous phase)CT of the abdomen showed a global enlargement of the right kidney. There are multiplelow attenuation areas in the renal parenchyma, in a ‘hydronephrotic type manner’, but with no true hydronephrosis. This is due to a renal calculus lying in a contracted pelvis with dilated calyces that contain inflammatory debris. A rim of normal renal tissue enhancesperipherally. The appea...

  7. Anti-backlash gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  8. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. PMID:25775930

  9. Bearings only naval tracking

    Energy Technology Data Exchange (ETDEWEB)

    Barth, M.J.

    1984-11-01

    Two commonly used Extended Kalman Filter tracking algorithms utilize the Relative Cartesian and Modified Polar coordinate systems. This report compares the two algorithms by exercising a destroyer-Submarine (DD/SS) computer simulation. A simple engagement geometry is employed which encompasses the major DD/SS options available. Error statistics are developed by Monte Carlo methods. Results are presented which show that the circular error depends upon the diagonal values of the error covariance matrix. The results also support (but do not establish) that the optimum DD manuevuer is that which minimizes the range while maximizing the bearing rate. 4 refs., 5 figs., 4 tabs.

  10. Self lubricating fluid bearings

    International Nuclear Information System (INIS)

    The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid

  11. Superconducting bearings in flywheels

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, T.A.; Campbell, A.M.; Ganney, I.; Lo, W. [Cambridge Univ. (United Kingdom). Interdisciplinary Research Centre in Superconductivity (IRC); Twardowski, T. [International Energy Systems, Chester High Road, Neston, South Wirral (United Kingdom); Dawson, B. [British Nuclear Fuels, Capenhurst, South Wirral (United Kingdom)

    1998-05-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.) 5 refs.

  12. Superconducting bearings in flywheels

    International Nuclear Information System (INIS)

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.)

  13. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  14. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  15. The Reactivity of Thymine and Thymidine 5,6-Epoxides with Organometallic Reagents - A Route to Thymidine (6-4) Photoproduct Analogues.

    Science.gov (United States)

    Wrigstedt, Pauli; Kavakka, Jari; Heikkinen, Sami; Nieger, Martin; Räisänen, Minna; Repo, Timo

    2016-05-01

    This report describes an efficient procedure for the generation and isolation of various thymine and thymidine 5,6-epoxides from the corresponding trans-5,6-bromohydrins by reaction with triethylamine. The quantitative isolation of the epoxides, accomplished by solvent precipitation of triethylamine hydrobromide, enabled their regiospecific ring-opening at C6 position by organometallic nucleophiles. The reaction was amenable to a broad range of alkyl, aryl, alkenyl, and alkynyl organomagnesium, -zinc, -aluminum, or -boron reagents, although the reactivity was strongly affected by the electronic effects of N3 protecting group. Additionally, the reaction featured excellent cis-diastereoselectivity providing access to C6-carbon-functionalized dihydrothymidine cis-alcohols, which are synthetic derivatives of UV-induced DNA lesions, namely, thymidine (6-4) photoproducts. PMID:27080560

  16. Laser flash photolysis and magnetic-field-effect studies on interaction of thymine and thymidine with menadione: role of sugar in controlling reaction pattern

    International Nuclear Information System (INIS)

    The magnetic field effect (MFE) in conjunction with laser flash photolysis has been used for the study of the interaction of one of the small drug like quinone molecules, 2-methyl, 1,4-naphthoquinone, commonly known as menadione (MQ), with one of the DNA bases, thymine (THN), and its corresponding nucleoside, thymidine (THDN), in acetonitrile (ACN) and sodium dodecylsulfate (SDS) micelles. It has been observed that THN undergoes electron transfer (ET) and hydrogen (H) abstraction with MQ, while THDN undergoes only H abstraction in both the media. However, our earlier studies showed that a purine base, adenine (ADN), and its nucleoside, 2'-deoxyadenosine (ADS), undergo ET in ACN and H abstraction in SDS. Here we have attempted to explain the differences in the reactions of these DNA bases with MQ. We also reveal the crucial role of a sugar unit in altering the behavior of purine and pyrimidine bases with respect to ET and H abstraction

  17. Laser flash photolysis and magnetic-field-effect studies on interaction of thymine and thymidine with menadione: role of sugar in controlling reaction pattern

    Directory of Open Access Journals (Sweden)

    Adity Bose, Debarati Dey and Samita Basu

    2008-01-01

    Full Text Available The magnetic field effect (MFE in conjunction with laser flash photolysis has been used for the study of the interaction of one of the small drug like quinone molecules, 2-methyl, 1,4-naphthoquinone, commonly known as menadione (MQ, with one of the DNA bases, thymine (THN, and its corresponding nucleoside, thymidine (THDN, in acetonitrile (ACN and sodium dodecylsulfate (SDS micelles. It has been observed that THN undergoes electron transfer (ET and hydrogen (H abstraction with MQ, while THDN undergoes only H abstraction in both the media. However, our earlier studies showed that a purine base, adenine (ADN, and its nucleoside, 2'-deoxyadenosine (ADS, undergo ET in ACN and H abstraction in SDS. Here we have attempted to explain the differences in the reactions of these DNA bases with MQ. We also reveal the crucial role of a sugar unit in altering the behavior of purine and pyrimidine bases with respect to ET and H abstraction.

  18. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  19. Fish of Bear Lake, Utah

    OpenAIRE

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    There are 13 species of fish found in the waters of Bear Lake. Of those 13, 4 are endemic (found only in Bear Lake). The 4 endemics species are Bonneville cisco, Bonneville whitefish, Bear Lake whitefish, and Bear Lake sculpin. Five of the remaining 9 fish species are native to the region, and 4 are exotic introductions. These native fishes are the Bonneville cutthroat trout, Utah sucker, redside shiner, speckled dace and Utah chub. The exotic fishes are lake trout, common carp, yellow p...

  20. Dynamic Analysis of Engine Bearings

    Directory of Open Access Journals (Sweden)

    H. Hirani

    1999-01-01

    Full Text Available This paper presents a simple methodology to evaluate the stiffness and damping coefficients of an engine bearing over a load cycle. A rapid technique is used to determine the shaft ‘limit cycle’ under engine dynamic loads. The proposed theoretical model is based on short and long bearing approximations. The results obtained by present approximation are compared with those obtained by numerical method. The influence of thermal effects on the stiffness and damping coefficients is predicted by using a simplified thermal analysis. In order to illustrate the application of the proposed scheme, one engine main bearing and a connecting rod bearing are analysed.

  1. Autosizing Control Panel for Needle Bearing

    OpenAIRE

    Prof.A.R.Wadhekar,; Ms Jyoti R. Rajput

    2016-01-01

    A needle roller bearing is a bearing which uses small cylindrical rollers. Bearings are used to reduce friction of any rotating surface. Needle bearings have a large surface in contact with the bearing outer surfaces as compared to ball bearings. There is less added clearance(Diameter of the shaft and the diameter of the bearing are different) so they are much compact. The structure consists of a needle cage which contains the needle rollersthemselves and an outer race (The housin...

  2. The use of {sup 99m}Tc-thymine to identify metastatic disease in dogs presenting the cutaneous form of canine transmissible venereal tumor; Uso da {sup 99m}Tc-timina na identificacao de metastases de tumor venereo transmissivel canino com apresentacao cutanea

    Energy Technology Data Exchange (ETDEWEB)

    Castelo-Branco, Paulo S.M. [Universidade Estacio de Sa, Rio de Janeiro, RJ (Brazil)]. E-mail: p.castelobranco@ig.com.br; Castro, Veronica; Sena, Priscila [Sociedade Uniao Internacional Protetora dos Animais (SUIPA), Rio de Janeiro, RJ (Brazil); Souza, Sergio A. Lopes de; Lopes, Flavia P.P. Lobo; Pereira, Joao Batista; Fonseca, Lea M. Barbosa da; Gutfilen, Bianca [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil). Dept. de Radiologia

    2008-08-15

    The venereal canine transmissible tumor (VCTT) is described in literature as a rare metastatic tumor. However accurate methods for verification of this affirmative are not available in the veterinary medicine routine. In this study, we evaluated the dissemination from VCTT with cutaneous presentation using the {sup 99m}Tc-Thymine scintigraphy. The labelled thymine was up taken by the three cases of VCTT. {sup 99m}Tc-Thymine is a promising imaging technique for non-invasive veterinarian evaluation of tumoral dissemination degree decurrent from the VCTT cases. (author)

  3. Superconducting bearings for flywheel applications

    OpenAIRE

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings in flywheels.

  4. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  5. What about the Javan Bear?

    NARCIS (Netherlands)

    Jentink, F.A.

    1898-01-01

    The other day I read in a dutch popular periodical a paper dealing with the different species of Bears and their geographical distribution. To my great surprise the Malayan Bear was mentioned from Java: the locality Java being quite new to me I wrote to the author of that paper and asked him some in

  6. Space Station alpha joint bearing

    Science.gov (United States)

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  7. Fire safety of rubber bearings

    International Nuclear Information System (INIS)

    The objective of the study is to experimentally evaluate the fire resistance of the natural-rubber bearings to be incorporated into a Fast Reactor (FBR) under study. Four experiments were performed to look at the effect of bearing diameters and heating conditions on the performance. The full-scale specimen sustained the design-basis load for more than 3.5 hours under 'standard fire.' Medium-size bearings showed resistance for 2-4 hours, according to heating temperatures. The paper also summarizes the methods and the results of simulation analyses of rubber bearings subjected to load/temperature conditions under fire. The vertical deformation of the bearings can be calculated very well, using the temperature profiles obtained from testing. However, the heat transfer analyses did not give good results, especially in the cases/portions where heat was generated due to rubber combustion. (author)

  8. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

    OpenAIRE

    Cahill, J.; Stirling, I.; Kistler, L.; Salamzade, R.; Ersmark, E.; Fulton, T.; Stiller, M.; Green, R.; Shapiro, B.

    2015-01-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear...

  9. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  10. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  11. eBear: An Expressive Bear-Like Robot

    OpenAIRE

    Zhang, Xiao; Mollahosseini, Ali; B., Amir H. Kargar; Boucher, Evan; Voyles, Richard M.; Nielsen, Rodney; Mahoor, Mohammd H.

    2015-01-01

    This paper presents an anthropomorphic robotic bear for the exploration of human-robot interaction including verbal and non-verbal communications. This robot is implemented with a hybrid face composed of a mechanical faceplate with 10 DOFs and an LCD-display-equipped mouth. The facial emotions of the bear are designed based on the description of the Facial Action Coding System as well as some animal-like gestures described by Darwin. The mouth movements are realized by synthesizing emotions w...

  12. Mixed-mu superconducting bearings

    Science.gov (United States)

    Hull, John R.; Mulcahy, Thomas M.

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  13. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  14. Failure analysis of superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Amit; Campbell, A M; Coombs, T A [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2006-06-01

    The dynamics of superconductor bearings in a cryogenic failure scenario have been analyzed. As the superconductor warms up, the rotor goes through multiple resonance frequencies, begins to slow down and finally touches down when the superconductor goes through its transition temperature. The bearing can be modelled as a system of springs with axial, radial and cross stiffness. These springs go through various resonant modes as the temperature of the superconductor begins to rise. We have presented possible explanations for such behavio0008.

  15. Failure analysis of superconducting bearings

    International Nuclear Information System (INIS)

    The dynamics of superconductor bearings in a cryogenic failure scenario have been analyzed. As the superconductor warms up, the rotor goes through multiple resonance frequencies, begins to slow down and finally touches down when the superconductor goes through its transition temperature. The bearing can be modelled as a system of springs with axial, radial and cross stiffness. These springs go through various resonant modes as the temperature of the superconductor begins to rise. We have presented possible explanations for such behaviour

  16. Genetic effects of decay of tritium incorporated into cells of yeast Saccharomyces cerevisiae. 5. Lethal and mutagenic effects and the nature of mutations induced by /sup 3/H decay in the 6-th position of thymine

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, E.L.; Korolev, V.G. (AN SSSR, Leningrad. Inst. Yadernoj Fiziki)

    1982-03-01

    Lethal and mutagenous effects as well as nature of mutations induced with /sup 3/H decay in the sixth position of thymine (6-/sup 3/H-T) have been studied. Inactivation probability of haploid yeasts constituted ..cap alpha..=(6.1+-1.0)x10/sup -3/ decay/sup -1/ or ..cap alpha..=(7.6+-1.3)x10/sup -5/ rad/sup -1/, and probability of mutation appearance in genes ade 1, ade -K is (2.8+-1.7)x10/sup -8/ decay/sup -1/ or K=(3.5+-2.1)x10/sup -10/ rad/sup -1/. Lethal and mutageneous effects of 6-/sup 3/H-T don't differ considerably from those for /sup 3/H decay in the fifth position of thymine (5-/sup 3/H-T). From the point of view of frequency of transversions and mutations of read-out frame shift type induced in ade 2 gene, 6-/sup 3/H-T doesn't differ from 5-/sup 3/H-T. However, in comparison with the latter 6-/sup 3/H-T causes appearance of a larger amount of AT ..-->.. GTs transitions. A scheme, according to which 5 methyl barbituric acid (5MBK) is a finite product of /sup 3/H decay in the sixth position of thymine, is suggested. The results obtained point to that fact that 5MBK represents weak mutageneous damage of thymine causing the exchange of AT pair.

  17. Designing Rolling-Element Bearings

    Science.gov (United States)

    Moore, James D., Jr.

    2007-01-01

    Bearing Analysis Tool (BAT) is a computer program for designing rolling-element bearings for cryogenic turbomachines. BAT provides a graphical user interface (GUI) that guides the entry of data to develop mathematical models of bearings. The GUI breaks model data into logical subsets that are entered through logic-driven input screens. The software generates a threedimensional graphical model of a bearing as the data are entered. Most dataentry errors become immediately obvious in the graphical model. BAT provides for storage of all the data on a shaft/bearing system, enabling the creation of a library of proven designs. Data from the library can be transferred to subsequent projects by use of simple cut-and-paste routines. BAT includes a library of temperature- dependent cryogenic bearing-material properties for use in the mathematical models. BAT implements algorithms that (1) enable the user to select combinations of design and/or operating-condition parameters, and then (2) automatically optimize the design by performing trade studies over all of the parameter combinations. This feature enables optimization over a large trade space in a fraction of the time taken when using prior bearingmodel software.

  18. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Science.gov (United States)

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  19. A study of fast and metastable dissociations of adenine-thymine binary-base oligonucleotides by using positive-ion MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Chan, T W Dominic; Fung, Y M Eva; Li, Y C Leo

    2002-09-01

    In the present study, fast and metastable dissociations of a number of adenine-thymine binary-base oligonucleotides under the conditions of UV matrix-assisted laser desorption/ionization mass spectrometry were investigated. 2-Aminobenzoic acid/ammonium fluoride (ABA/NH4F) matrix system was used. The spectra obtained under metastable and fast dissociation conditions exhibit distinctive dissociation products. From the post-source-decay analysis, all oligonucleotides underwent predominantly metastable dissociations at the 3' C-O linkages to form [a(n)-B]+ and w(n)+ complimentary ion series. Based on the present results, the so-called "[wn+80]+" ions were postulated to be the complimentary [Z(8-n)AH]+ ions rather than the expected phosphate rearrangement products. In addition, these oligonucleotides were found to generate fast dissociation products of b(n)+, d(N)+, w(N)+ and y(N)+ ions through backbone cleavages at 5' C-O, 5' O-P, 3' C-O and 3' P-O linkages, respectively. Product ion series formed under PSD conditions were not observed. The implications of this mutually exclusive occurrence of the two sets of fragment ions under fast and metastable conditions using ABA/NH4F matrix would be discussed. A model of ion activation under UV-MALDI conditions was also proposed. PMID:12322953

  20. Increased sensitivity of UV-repair-deficient humancells to DNA bound platinum products which unlike thymine dimers are not recognised by an endonuclease extracted from Micrococcus luteus

    International Nuclear Information System (INIS)

    The response of human cells in culture to cis platinum [II] diammine dichloride (cis Pt[II]) induced DNA damage has been studied. The survival data, measured as a function of cis Pt[II] dose were similar in a normal cell line (Human foetal lung) compared to a UV-sensitive, thymine dimer excision repair-deficient cell line (Xeroderma pigmentatosum). However, there was a marked difference between the two cell lines when binding to DNA was plotted against dose of cis Pt[II] given for 1 h. When these findings were expressed as cell survival versus binding to DNA, a 4.1-fold difference between the slopes of the survival curves for the two cell lines was obtained. These findings are consistent with the notion that normal cells are able to excise cis Pt[II] induced damage from their genome and thus increase their ability to survive as compared to excision deficient cells. An endonuclease preparation from Micrococcus luteus is able to recognise UV damage in DNA, but did not recognise cis Pt[II] induced damage. These results possibly indicate differences in the pathways of repair of damage caused by the two agents. (Auth.)

  1. Bear reintroduction: Lessons and challenges

    Science.gov (United States)

    Clark, Joseph D.; Huber, Djuro; Servheen, Christopher

    2002-01-01

    Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. Historically, one of the most successful programs was the reintroduction of 254 American black bears (Ursus americanus) from Minnesota to the Interior Highlands of Arkansas in the 1960s; that population has grown to >2,500 today. More recent efforts have involved fewer but better monitored animals and have sometimes employed techniques to improve site fidelity and survival. In Pennsylvania, for example, pregnant female American black bears were successfully translocated from winter dens, the premise being that the adult females would be less likely to return because of the presence of young cubs. That winter-release technique was compared to summer trapping and release in Tennessee; winter releases resulted in greater survival and reduced post-release movements. Homing has not been a problem for small numbers of brown bears (Ursus arctos) reintroduced to the Cabinet-Yaak ecosystem in Montana and Idaho and to the mountains of Austria and France. Reintroduction success appears to be correlated with translocation distance and is greater for subadults and females. As with any small population, reintroduced bear populations are susceptible to environmental variation and stochastic demographic and genetic processes. Although managers have focused on these biological barriers, sociopolitical impediments to bear reintroduction are more difficult to overcome. Poor public acceptance and understanding of bears are the main reasons some reintroduction programs have been derailed. Consequently, the public should be involved in the reintroduction process from the outset; overcoming negative public perceptions about bear reintroduction will be our greatest challenge.

  2. 49 CFR 229.69 - Side bearings.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Side bearings. 229.69 Section 229.69....69 Side bearings. (a) Friction side bearings with springs designed to carry weight may not have more than 25 percent of the springs in any one nest broken. (b) Friction side bearings may not be run...

  3. 36 CFR 13.1236 - Bear orientation.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bear orientation. 13.1236... Developed Area § 13.1236 Bear orientation. All persons visiting the BCDA must receive an NPS-approved Bear Orientation. Failure to receive an NPS-approved Bear Orientation is prohibited....

  4. Neisseria gonorrhoeae FA1090 Carries Genes Encoding Two Classes of Vsr Endonucleases ▿

    OpenAIRE

    Kwiatek, Agnieszka; Łuczkiewicz, Maciej; Bandyra, Katarzyna; Stein, Daniel C.; Piekarowicz, Andrzej

    2010-01-01

    A very short patch repair system prevents mutations resulting from deamination of 5-methylcytosine to thymine. The Vsr endonuclease is the key enzyme of this system, providing sequence specificity. We identified two genes encoding Vsr endonucleases V.NgoAXIII and V.NgoAXIV from Neisseria gonorrhoeae FA1090 based on DNA sequence similarity to genes encoding Vsr endonucleases from other bacteria. After expression of the gonococcal genes in Escherichia coli, the proteins were biochemically chara...

  5. Superconductor bearings, flywheels and transportation

    Science.gov (United States)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  6. Superconductor bearings, flywheels and transportation

    International Nuclear Information System (INIS)

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS–FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  7. Future Bearing Surfaces in Total Hip Arthroplasty

    OpenAIRE

    Chang, Jun-Dong

    2014-01-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom...

  8. 'Dodo' and 'Baby Bear' Trenches

    Science.gov (United States)

    2008-01-01

    NASA's Phoenix Mars Lander's Surface Stereo Imager took this image on Sol 11 (June 5, 2008), the eleventh day after landing. It shows the trenches dug by Phoenix's Robotic Arm. The trench on the left is informally called 'Dodo' and was dug as a test. The trench on the right is informally called 'Baby Bear.' The sample dug from Baby Bear will be delivered to the Phoenix's Thermal and Evolved-Gas Analyzer, or TEGA. The Baby Bear trench is 9 centimeters (3.1 inches) wide and 4 centimeters (1.6 inches) deep. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  9. Trends in Controllable Oil Film Bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar

    2011-01-01

    This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing .......e., as tilting-pad bearings, multirecess journal bearings and plain bearings.......This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing...... the rotational speed ranges by improving damping and eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing startup torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable bearings can act as...

  10. Delta-elimination by T4 endonuclease V at a thymine dimer site requires a secondary binding event and amino acid Glu-23.

    Science.gov (United States)

    Latham, K A; Lloyd, R S

    1995-07-11

    Endonuclease V from bacteriophage T4 is a well characterized enzyme that initiates the repair of ultraviolet light induced pyrimidine dimers. Scission of the phosphodiester backbone between the pyrimidines within a dimer, or 3' to an abasic (AP) site, occurs by a beta-elimination mechanism. In addition, high concentrations of endonuclease V have been reported to catalyze the cleavage of the C5'-O-P bond in a reaction referred to as delta-elimination. To better understand the enzymology of endonuclease V, the delta-elimination reaction of the enzyme has been investigated using an oligonucleotide containing a site-specific cis-syn cyclobutane thymine dimer. The slower kinetics of the delta-elimination reaction compared to beta-elimination and the ability of unlabeled dimer-containing DNA to compete more efficiently for delta-elimination than beta-elimination indicate that delta-elimination most likely occurs during a separate enzyme encounter with the incised DNA. Previous studies have shown that both the alpha-amino group of the N-terminus and the acidic residue Glu-23 are necessary for the N-glycosylase and AP lyase activities of endonuclease V. Experiments with T2P, E23Q, and E23D mutants, which are defective in pyrimidine dimer-specific nicking, demonstrated that delta-elimination requires Glu-23, but not the primary amine at the N-terminus. In fact, the T2P mutant was much more efficient at promoting delta-elimination than the wild-type enzyme. Besides lending further proof that delta-elimination requires a second encounter between enzyme and DNA, this result may reflect an enhanced binding of the T2P mutant to dimer-containing DNA. PMID:7612620

  11. EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

    Directory of Open Access Journals (Sweden)

    Jarosław KACZOR

    2014-06-01

    Full Text Available Durability deep groove ball bearings depends on factors (called attributes design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bearings to work three-bearing shafts, including elasticity and resilience three-bearing shafts.

  12. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  13. Mobile bearing and fixed bearing total knee arthroplasty

    Science.gov (United States)

    Dolfin, Marco; Saccia, Francesco

    2016-01-01

    The mobile bearing (MB) concept in total knee arthroplasty (TKA) was developed as an alternative to fixed bearing (FB) implants in order to reduce wear and improve range of motion (ROM), especially focused on younger patients. Unfortunately, its theoretical advantages are still controversial. In this paper we exhibit a review of the more recent literature available comparing FB and MB designs in biomechanical and clinical aspects, including observational studies, clinical trials, national and international registries analyses, randomized controlled trials, meta-analyses and Cochrane reviews. Except for some minor aspects, none of the studies published so far has reported a significant improvement related to MBs regarding patient satisfaction, clinical, functional and radiological outcome or medium and long-term survivorship. Thus the presumed superiority of MBs over FBs appears largely inconsistent. The routine use of MB is not currently supported by adequate evidences; implant choice should be therefore made on the basis of other factors, including cost and surgeon experience. PMID:27162777

  14. 5-METHYLCYTOSINE IN CPG SITES AND THE REACTIVITY OF NEAREST NEIGHBORING GUANINES TOWARD THE CARCINOGEN AFLATOXIN B1-8,9-EPOXIDE. (R825809)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  15. Effects of bearing deadbands on bearing loads and rotor stability

    Science.gov (United States)

    1984-01-01

    A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

  16. Live-trapping and handling brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper reports techniques developed to live trap and handle brown bears on the Kodiak National Wildlife Refuge. The brown bears (Ursus middendorffi) on the...

  17. Brown bear telemetry and trapping: Special report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brown bear studies were continued during the 1967 field season with emphasis on development of techniques for instrumenting bears with radio transmitters and...

  18. Goose Eggs Could Save Polar Bears

    Institute of Scientific and Technical Information of China (English)

    孙淑敏

    2009-01-01

    Polar bears could avoid extinction despitemany starving to death in coming years, ac-cording to scientists and other observers whohave discovered that some of the bears havefound a new food source--goose and duckeggs.

  19. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... the years. In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work, but the...

  20. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Science.gov (United States)

    Hopkins, John B., III; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  1. Oil film pressure in hydrodynamic journal bearings

    OpenAIRE

    Valkonen, Antti

    2009-01-01

    Hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in various machines. Therefore, knowing the true operating conditions of hydrodynamic journal bearings is essential to machine design. Oil film pressure is one of the key operating parameters describing the operating conditions in hydrodynamic journal bearings. Measuring the oil film pressure in bearings has been a demanding task and theref...

  2. Mercury in polar bears from Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  3. Technology development for indigenous water lubricated bearings

    International Nuclear Information System (INIS)

    Water Lubricated Bearings (WLB) are used in various mechanisms of fuel handling systems of PHWRs and AHWR. Availability and random failures of these bearings was a major factor in refuelling operations. Indigenous development of these bearings was taken up and 7 types of antifriction bearings in various sizes (totaling 37 variants) for PHWR, AHWR and Dhruva applications were successfully developed. This paper deals with various aspects of WLB development. (author)

  4. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  5. 49 CFR 229.64 - Plain bearings.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Plain bearings. 229.64 Section 229.64 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION....64 Plain bearings. A plain bearing box shall contain visible free oil and may not be cracked to...

  6. Passive Thermal Management of Foil Bearings

    Science.gov (United States)

    Bruckner, Robert J. (Inventor)

    2015-01-01

    Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

  7. Hazards within the Bear Lake basin, Utah

    OpenAIRE

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    The Bear Lake basin developed from fault subsidence that continues today, slowly deepening the lake along the eastern side. The Bear Lake graben is about 5 miles long and 4.3-8.6 miles wide. It extends across the Utah-Idaho border and involves faults on both eastern and western sides of Bear Lake....

  8. Virginia Tech Bear Researchers Ensure Populations

    OpenAIRE

    Davis, Lynn

    2003-01-01

    The Cooperative Alleghany Bear Study (CABS) was initiated in 1994 as a 10-year study to ensure survival of Virginia's hunted black bear population of western Virginia. During the first six years of the study, researchers have placed radio collars on 376 of the 746 bears captured.

  9. The vented pressure fed gas journal bearing

    International Nuclear Information System (INIS)

    Hydrodynamic-type gas journal bearings with stabilising venting slots are often operated hydrostatically during starting-up as a means of 'jacking'. A simplified mathematical treatment of the circumferential gas flows in a vented, pressure-fed journal bearing is used to predict the relationship between load capacity, bearing geometry and gas properties. (author)

  10. Cool Polar Bears: Dabbing on the Texture

    Science.gov (United States)

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  11. Fractal analysis of polar bear hairs

    Directory of Open Access Journals (Sweden)

    Wang Qing-Li

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus are of superior properties such as the excellent thermal protection. Why do polar bears can resist such cold environment? The paper concludes that its fractal porosity plays an important role, and its fractal dimensions are very close to the golden mean, 1.618, revealing the possible optimal structure of polar bear hair.

  12. Microstructural degradation of bearing steels

    OpenAIRE

    Solano Alvarez, Wilberth

    2015-01-01

    The aim of the work presented in this thesis is to clarify one of the most fundamental aspects of fatigue damage in bearings steels through critical experiments, in particular whether damage in the form of cracks precedes hard ?white-etching matter" formation, which is carbon supersaturated nanoscaled ferrite. Heat treatments have been designed to create four different crack types and distributions: scarce martensite plate cracks, fine grain boundary cracks, abundant martensite plate cracks, ...

  13. Elid superfinishing of spherical bearings

    OpenAIRE

    Raffles, Mark H.

    2007-01-01

    Driven by a requirement to extend the lifespan of self-aligning lined spherical bearings, this research investigates the use of Elid (electrolytic in-process dressing) as a method of improving ball surface finish. Elid is a continuous and self-regulating electrochemical dressing process that modifies the surface of a grinding, lapping, or superfinishing wheel. It provides improved grit protrusion, impedes wheel loading / glazing and promotes effective cutting. The characteri...

  14. Risk-bearing and Entrepreneurship

    OpenAIRE

    Newman, Andrew

    2007-01-01

    In the 'Knightian' theory of entrepreneurship, entrepreneurs provide insurance to workers by paying fixed wages and bear all the risk of production. This paper endogenizes entrepreneurial risk by allowing for optimal insurance contracts as well as the occupational self-selection. Moral hazard prevents full insurance; increases in an agent’s wealth then entail increases in risk borne. Thus, even under decreasing risk aversion, there are robust instances in which workers are wealthier than entr...

  15. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    OpenAIRE

    Andrzej RACZYŃSKI; Jarosław KACZOR

    2014-01-01

    Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  16. EFFECT OF PRELOAD OF ANGULAR CONTACT BALL BEARINGS ON LIFE OF BEARINGS

    Directory of Open Access Journals (Sweden)

    Andrzej RACZYŃSKI

    2014-06-01

    Full Text Available Angular contact ball bearings are commonly used in such situations when you need to reach high bearing stiffness. However, a significant stiffness increase can be achieved only through the introduction of preload to the angular contact bearings. The purpose of this paper is to present a method for assessing the effect of preload of the angular contact bearings for their durability.

  17. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    Science.gov (United States)

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  18. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  19. Ball Bearing Analysis with the ORBIS Tool

    Science.gov (United States)

    Halpin, Jacob D.

    2016-01-01

    Ball bearing design is critical to the success of aerospace mechanisms. Key bearing performance parameters, such as load capability, stiffness, torque, and life all depend on accurate determination of the internal load distribution. Hence, a good analytical bearing tool that provides both comprehensive capabilities and reliable results becomes a significant asset to the engineer. This paper introduces the ORBIS bearing tool. A discussion of key modeling assumptions and a technical overview is provided. Numerous validation studies and case studies using the ORBIS tool are presented. All results suggest the ORBIS code closely correlates to predictions on bearing internal load distributions, stiffness, deflection and stresses.

  20. Valve assembly having remotely replaceable bearings

    Science.gov (United States)

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  1. Heuristic explanation of journal bearing instability

    Science.gov (United States)

    Crandall, S. H.

    1982-01-01

    A fluid-filled journal bearing is viewed as a powerful pump circulating fluid around the annular space between the journal and the bearing. A small whirling motion of the journal generates a wave of thickness variation progressing around the channel. The hypothesis that the fluid flow drives the whirl whenever the mean of the pumped fluid velocity is greater than the peripheral speed of the thickness variation wave is discussed and compared with other simple explanations of journal bearing instability. It is shown that for non-cavitation long bearings the hypothesis predicts instability onset correctly for unloaded bearings but gradually overpredicts the onset speed as the load is increased.

  2. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    OpenAIRE

    Yu Lie; R.B. Bhat

    1995-01-01

    The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distri...

  3. Components of bull and bear markets: bull corrections and bear rallies

    OpenAIRE

    Maheu, John M; Thomas H. McCurdy; Yong Song

    2010-01-01

    Existing methods of partitioning the market index into bull and bear regimes do not identify market corrections or bear market rallies. In contrast, our probabilistic model of the return distribution allows for rich and heterogeneous intra-regime dynamics. We focus on the characteristics and dynamics of bear market rallies and bull market corrections, including, for example, the probability of transition from a bear market rally into a bull market versus back to the primary bear state. A Baye...

  4. Chromatographic (TLC) differentiation of grizzly bear and black bear scats

    Science.gov (United States)

    Picton, Harold D.; Kendall, Katherine C.

    1994-01-01

    While past work concluded that thin-layer chromatography (TLC) was inadequate for the separation of grizzly (Ursus arctos horribilis) and black bear (U. americanus) scats, our study found differences adequate for species separation. A key was constructed using 19 of 40 data points recorded on each(N)=356 profiles of 178) know-species scat. Accuracy was best for late summer scats (94%). Methods for specimen preparation, analysis, and reading the TLC profiles are discussed. Factors involved in scat variation were tested.

  5. A prototype construction of bearing heater system

    International Nuclear Information System (INIS)

    A bearing heater system has been successfully constructed using transformer-like method of 1000 VA power, 220 V primary voltage, and 50 Hz electrical frequency. The bearing heater consists of primary coil 230 turns, U type and bar-type iron core with 36 cm2, 9 cm2 ,and 3 cm2 cross-section, and electrical isolation. The bearing heater is used to enlarge the diameter of the bearing so that it can be easily fixed on an electric motor shaft during replacement because the heating is conducted by treated the bearing as a secondary coil of a transformer. This bearing heater can be used for bearing with 3 and 6 cm of inner diameter and 12 cm of maximum outside diameter. (author)

  6. Wave Journal Bearings Under Dynamic Loads

    Science.gov (United States)

    Hendricks, Robert C.; Dimofte, Florin

    2002-01-01

    The dynamic behavior of the wave journal bearing was determined by running a three-wave bearing with an eccentrically mounted shaft. A transient analysis was developed and used to predict numerical data for the experimental cases. The three-wave journal bearing ran stably under dynamic loads with orbits well inside the bearing clearance. The orbits were almost circular and nearly free of the influence of, but dynamically dependent on, bearing wave shape. Experimental observations for both the absolute bearing-housing-center orbits and the relative bearing-housing-center-to-shaft-center orbits agreed well with the predictions. Moreover, the subsynchronous whirl motion generated by the fluid film was found experimentally and predicted theoretically for certain speeds.

  7. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears.

    Science.gov (United States)

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-03-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. PMID:25490862

  8. Development and Evaluation of Titanium Spacesuit Bearings

    Science.gov (United States)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Raymond, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z-series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z-series space suit architecture allows us to reduce mass by an estimated 23 lbs per suit system compared to the previously used stainless steel bearing race designs, without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race- 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility (WSTF) that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approx. 3 years), design parameters for maximum contact stress need to be identified. To identify these design parameters, bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination and design around a cycle life requirement for an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an

  9. Hydrostatic bearings for a turbine fluid flow metering device

    Science.gov (United States)

    Fincke, J.R.

    1980-05-02

    A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

  10. Conditioning of alpha bearing wastes

    International Nuclear Information System (INIS)

    Alpha bearing wastes are generated during the reprocessing of spent fuel, mixed oxide fuel fabrication, decommissioning and other activities. The safe and effective management of these wastes is of particular importance owing to the radiotoxicity and long lived characteristics of certain transuranic (TRU) elements. The management of alpha bearing wastes involves a number of stages which include collection, characterization, segregation, treatment, conditioning, transport, storage and disposal. This report describes the currently available matrices and technologies for the conditioning of alpha wastes and relates them to their compatibility with the other stages of the waste management process. The selection of a specific immobilization process is dependent on the waste treatment state and the subsequent handling, transport, storage and disposal requirements. The overall objectives of immobilization are similar for all waste producers and processors, which are to produce: (a) Waste forms with sufficient mechanical, physical and chemical stability to satisfy all stages of handling, transport and storage (referred to as the short term requirements), and (b) Waste forms which will satisfy disposal requirements and inhibit the release of radionuclides to the biosphere (referred to as the long term requirements). Cement and bitumen processes have already been successfully applied to alpha waste conditioning on the industrial scale in many of the IAEA Member States. Cement systems based on BFS and pozzolanic cements have emerged as the principal encapsulation matrices for the full range of alpha bearing wastes. Alternative technologies, such as polymers and ceramics, are being developed for specific waste streams but are unlikely to meet widespread application owing to cost and process complexity. The merits of alpha waste conditioning are improved performance in transport, storage and disposal combined with enhanced public perception of waste management operations. These

  11. Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

    Science.gov (United States)

    Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

    2016-01-01

    Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. PMID:26264178

  12. Seismic isolation rubber bearings for nuclear facilities

    International Nuclear Information System (INIS)

    This paper describes results of biaxial breaking tests by compression and shear and by tension and shear for seismic isolation rubber bearings with bolted-type connections. The bearings used in the tests were low-damping rubber bearings, high-damping rubber bearings, and lead-rubber bearings. Three modes of failure of the bolted-type bearings were observed in the tests. They are the breaking failure by tension and shear; the breaking failure by compression and shear; and the buckling failure by compression and shear. The first and the second modes of failures are almost independent of the types and the sizes of the bearings. The breaking conditions of those failure modes are described in the axial stress-shear strain plane. This expression is useful for the evaluation of safety margins of the bearings. The paper outlines the basic design of the nuclear-grade bearings which were used for large-scale rubber bearing tests in a research project for seismic isolation of fast breeder reactor (FBR) plants. The paper also discusses the protection method against aging and the quality control which are important for implementation

  13. Interference Fit Life Factors for Roller Bearings

    Science.gov (United States)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2008-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner ring interference fit. Calculations were performed for up to seven interference fit classes for each of ten bearing sizes. Each fit was taken at tightest, average and loosest values within the fit class for RBEC-5 tolerance, thus requiring 486 separate analyses. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. The method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings based on interference fit. All calculated lives are for zero initial bearing internal clearance. Any reduction in bearing clearance due to interference fit was compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate and heavy loads and interference fits ranging from extremely light to extremely heavy and for bearing accuracy class RBEC 5 (ISO class 5). Interference fits on the inner bearing ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference fit life factors for a particular fit. The tightest fit at the high end of the RBEC-5 tolerance band defined in ANSI/ABMA shaft fit tables produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  14. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Directory of Open Access Journals (Sweden)

    Yu Lie

    1995-01-01

    Full Text Available The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distribution of journal bearings and the static deflection of the rotor and delays the instability of the system considerably in lateral shaft vibration.

  15. Bearing Health Assessment Based on Chaotic Characteristics

    Directory of Open Access Journals (Sweden)

    Chen Lu

    2013-01-01

    Full Text Available Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM. Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.

  16. Hydrodynamic bearing for light loaded turbo machinery

    International Nuclear Information System (INIS)

    The rotor of any turbo-machinery running in journal bearings is prone to two types of well-known vibrations. Synchronous Vibrations occur due to run out or forces resulting from unbalancing of the shaft. Sub synchronous vibrations are more serious, this phenomenon is commonly associated with oil film forces of the journal bearing. In order to avoid sub synchronous vibrations, different types of journal bearings having helical grooves were investigated both theoretically and experimentally. (author)

  17. Probabilistic Aspect of Rolling Bearings Durability

    OpenAIRE

    Styp-Rekowski, Michał

    2007-01-01

    Many factors generate situations that real dimensions of each machine elements are different from nominal ones. In the case of rolling bearings elements mentioned disagreements are small - their values are rank of micrometers. However, such small differences can generate significant changes of operational features of bearings. The analysis of influence of ball dimensional deviation on load distribution in ball bearings is presented in this paper. The probability of occurrence of ball diameter...

  18. A miniature tilting pad gas lubricated bearing

    Science.gov (United States)

    Sixsmith, H.; Swift, W. L.

    1983-12-01

    This paper describes the design and development of a miniature tilting pad gas bearing developed for use in very small turbomachines. The bearings have been developed for cryogenic turboexpanders with shaft diameters down to about 0.3 cm and rotational speeds up to one million rpm. Cryogenic expansion turbines incorporating this type of bearing should be suitable for refrigeration rates down to about 10 w.

  19. Bearing fault diagnosis based on vibration signals.

    OpenAIRE

    Abdusslam, S.A.; Gu, Fengshou; Ball, Andrew

    2009-01-01

    The vibration signal obtained from operating machines contains information relating to machine condition as well as noise. Further processing of the signal is necessary to elicit information particularly relevant to bearing faults. Many techniques have been employed to process the vibration signals in bearing faults detection and diagnosis. Two common techniques, time domain techniques and frequency domain techniques are used in this paper to investigate bearings condition.

  20. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers

    International Nuclear Information System (INIS)

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL)

  1. Bear Capture. Research, and Request for Consideraton of Releases of Bears at Dahomey NWR in 1996

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A series of memos and correspondences concerning the capture of a bear in Cleveland, MS and release on Dahomey NWR along with graduate research on bears from...

  2. Dynamic modelling and response characteristics of a magnetic bearing rotor system with auxiliary bearings

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1995-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied.

  3. Dynamic modelling and response characteristics of a magnetic bearing rotor system including auxiliary bearings

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1993-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotor-dynamic model and assess the dynamic behavior of a magnetic bearing rotor system which includes the effects of auxiliary bearings. Of particular interest is the effects of introducing sideloading into such a system during failure of the magnetic bearing. A model is developed from an experimental test facility and a number of simulation studies are performed. These results are presented and discussed.

  4. Long-term bearing wear tests of conventional journal bearings and development of hydrostatic bearings for the LOFT drag-disc turbine transducer

    International Nuclear Information System (INIS)

    The details of a two-year development program concerning materials for use as turbine bearings in a pressurized water reactor environment are reported. Two types of bearings have been examined, both conventional journal bearings and hydrostatic bearings. The results of long-term bearing wear tests conducted at 590 K and 15.1 MPa in water are presented. The feasibility of using hydrostatic bearings for the same transducer is demonstrated

  5. Living in Bear Country: increasing municipal compliance with the Bear Smart Program in British Columbia

    OpenAIRE

    Hamilton, Anthony David

    2011-01-01

    Many communities in British Columbia are grappling with the presence of bears in their communities. The Ministry of Environment (MOE) created the Bear Smart Program in 2002 to assist these communities to prevent human-bear conflict. However, at the end of 2010 only two communities have completed the program. This study draws upon informant interviews and local documentation to develop a better understanding of why communities are participating but not completing the Bear Smart Program. Th...

  6. Journal bearing performance and metrology issues

    Directory of Open Access Journals (Sweden)

    S. Sharma

    2009-01-01

    Full Text Available Purpose: In this paper, a radial clearance of a journal bearings and the metrology of the radial clearance measurement is described.Design/methodology/approach: In this experimental study out-of-roundness and radial clearance of journal bearings were measured with high precision and the impact of their metrology was examined on the specific oil film thickness of the bearing. Some metrological issues were emerged and these should be taken into account when bearings are designed.Findings: An investigation showed that the radial clearance measurements can vary from one measuring device to another and the specified clearance may not necessarily meet the design criteria of specific oil film thickness. The study indicates that the radial clearance measurement can differ from one measuring device to another depending upon the precision that can be achieved by the device. The radius of the bearing or the shaft also varies along the circumference, mainly due to out-of-roundness. The out-of-roundness contributes to the error in radial clearance measurement and hence similar to the cut off length specified with the surface roughness, the out-of-roundness needs to be specified with the radial clearance.Practical implications: The radial clearance of a journal bearing is a key design parameter and bearing performance mainly depends upon this parameter. In this paper was showed that the metrology of the radial clearance measurement plays a significant role and not only that the bearing manufacturer or the user of the bearing is aware of this fact but the bearing designer must also take this fact into account while designing bearingsOriginality/value: This paper showed that The radial clearance is a sensitive micro-geometry parameter and hence metrology plays a vital role in making decisions

  7. Active magnetic bearing-supported rotor with misaligned cageless backup bearings: A dropdown event simulation model

    Science.gov (United States)

    Halminen, Oskari; Kärkkäinen, Antti; Sopanen, Jussi; Mikkola, Aki

    2015-01-01

    Active magnetic bearings (AMB) offer considerable benefits compared to regular mechanical bearings. On the other hand, they require backup bearings to avoid damage resulting from a failure in the component itself, or in the power or control system. During a rotor-bearing contact event - when the magnetic field has disappeared and the rotor drops on the backup bearings - the structure of the backup bearings has an impact on the dynamic actions of the rotor. In this paper, the dynamics of an active magnetic bearing-supported rotor during contact with backup bearings is studied with a simulation model. Modeling of the backup bearings is done using a comprehensive cageless ball bearing model. The elasticity of the rotor is described using the finite element method (FEM) and the degrees of freedom (DOF) of the system are reduced using component mode synthesis. Verification of the misaligned cageless backup bearings model is done by comparing the simulation results against the measurement results. The verified model with misaligned cageless backup bearings is found to correspond to the features of a real system.

  8. Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder

    2012-01-01

    bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas the...

  9. Phylogeography of mitochondrial DNA variation in brown bears and polar bears

    Science.gov (United States)

    Shields, Gerald F.; Adams, Deborah; Garner, Gerald; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

    2000-01-01

    We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

  10. Methods and systems for micro bearings

    Science.gov (United States)

    Stalford, Harold L.

    2012-10-09

    A micro drive assembly may comprise a substrate, a micro shall oriented in-plane with the substrate and at least one micro bearing to support rotation of the micro shaft. The micro shaft and micro bearing may be in or less than the micrometer domain.

  11. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  12. 33 CFR 117.543 - Bear Creek.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bear Creek. 117.543 Section 117.543 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.543 Bear Creek. (a) The draws of the...

  13. Friction coefficients of PTFE bearing liner

    Science.gov (United States)

    Daniels, C. M.

    1979-01-01

    Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

  14. Movie Director Bags a Silver Bear

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Chinese director and film writer Wang Xiaoshuai has walked away with the Silver Bear award at the 58th Berlin International Film Festival for best script of Zuo You, or In Love We Trust. Back in 2001, Wang won his first Silver Bear award for directing Beijing

  15. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this method...... over the years. In 1966 Jorgen W. Lund [5]published an approach to ¯nd the dynamic coe±cients of a journal bearing by a ¯rst order perturbation of the Reynold's equation. These coe±cients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coe±cients of the bearing could be used to ¯nd the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for ¯nding the damping coe±cients in this work, but the...

  16. Experimental investigations of active air bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    greatest challenges in a high-speed gas bearing design. A great deal of research is devoted to attack such issues, where most propose passive designs such as compliant foil bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic......Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread of...

  17. EFFECT OF CLEARANCE THE BALL BEARINGS ON INCORRECT WORK OF THREE-SUPORT BEARING SHAFT

    OpenAIRE

    Jarosław KACZOR

    2014-01-01

    Durability deep groove ball bearings depends on factors (called attributes) design, technological and operational. Among the design features one of the most important is play in the bearings. Polish Norm shows five groups of looseness in the bearings, in which the play range from 0 to 105 microns. Manufacturers of rolling bearings they only play group, which has a bearing data, without giving the exact value of the slack. Aim of this study is to determine how it affects the play in the bea...

  18. Effect of DNA target sequence on triplex formation by oligo-2′-deoxy- and 2′-O-methylribonucleotides

    OpenAIRE

    Cassidy, Rachel A.; Puri, Nitin; Miller, Paul S.

    2003-01-01

    The interactions of pyrimidine deoxyribo- or 2′-O-methylribo-psoralen-conjugated, triplex-forming oligonucleotides, psTFOs, with a 17-bp env-DNA whose purine tract is 5′-AGAGAGAAAAAAGAG-3′, or an 18-bp gag-DNA whose purine tract is 5′-AGG GGGAAAGAAAAAA-3′, were studied over the pH range 6.0–7.5. The stability of the triplex formed by a deoxy-env-psTFO containing 5-methylcytosines and thymines decreased with increasing pH (Tm = 56°C at pH 6.0; 27°C at pH 7.5). Replacement of 5-methylcytosines ...

  19. Genomic sequencing of Pleistocene cave bears

    Energy Technology Data Exchange (ETDEWEB)

    Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot; Krause, Johannes; Detter, J. Chris; Paabo, Svante; Rubin, Edward M.

    2005-04-01

    Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.

  20. Passive Magnetic Bearing With Ferrofluid Stabilization

    Science.gov (United States)

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  1. Intelligent monitoring of ball bearing conditions

    Science.gov (United States)

    Liu, T. I.; Mengel, J. M.

    1992-09-01

    Ball bearings are widely used in various kinds of robots, manufacturing machines, and equipment. In order to enhance productivity and improve product quality, an on-line monitoring system is essential to check the status of ball bearings. In this work, peak amplitude in the frequency domain, peak RMS, and the power spectrum were used as indirect indices to develop a system for monitoring and classifying ball bearing defects. These indices were then processed by artificial neural networks. Six different cases of ball bearing states were observed. The data from these observations were then input into neural networks with different architectures to train these neural networks in a learning process. All the trained neural networks are capable of distinguishing the normal bearings from defective bearings with a 100 percent success rate. They can also classify the bearing conditions into six different states with a success rate of up to 97 per cent. The effects of training set sizes and neural network structures on the monitoring performance have also been investigated.

  2. Design of gas bearing systems for precision applications

    Science.gov (United States)

    Wang, Junming

    Research to provide the up to date knowledge and efficient tools to design better Externally Pressurized Gas (EPG) bearing systems, including the design of individual bearings, and to arrange all the bearings used in an optimal way is reported. Both circular and rectangular EPG pads with rigid bearing surfaces and rigid inlet restrictors were used. The following topics closely related to the applications in precision engineering are discussed: influences of gap shape on the bearing performance; effects of bearing body tilt on the bearing performance; influences of bearing surface imperfections on bearing performance; temperature drops in EPG bearings in quasistationary conditions; the optimal use of multiple bearings in a mechanical system; the use of EPG bearing damping characteristics in the design; and the effects of motion velocity.

  3. Future bearing surfaces in total hip arthroplasty.

    Science.gov (United States)

    Chang, Jun-Dong

    2014-03-01

    One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements

  4. Compressor ported shroud for foil bearing cooling

    Science.gov (United States)

    Elpern, David G.; McCabe, Niall; Gee, Mark

    2011-08-02

    A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.

  5. Corporate risks, risk bearing ability and equity

    OpenAIRE

    Handschin, Lukas

    2011-01-01

    There is a relation between corporate risks, risk bearing ability and equity. In order to assess the risk bearing ability of a corporation, one reference figure is equity, understood as the sum of legal capital and reserves, free reserves and accrued profits. Equity shows the risk bearing ability related to the risk of asset reduction as well as the ability of the corporation to attract new liquidity by increasing debts, in case of a negative free cash flow. Equity is the risk reserve of the ...

  6. Hydrostatic, aerostatic and hybrid bearing design

    CERN Document Server

    Rowe, W Brian

    2012-01-01

    Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: Clear e

  7. Microeconomic analysis of military aircraft bearing restoration

    Science.gov (United States)

    Hein, G. F.

    1976-01-01

    The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

  8. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement with...

  9. Bear bile: dilemma of traditional medicinal use and animal protection

    OpenAIRE

    Nagamatsu Tadashi; Tsao Sai-Wah; Ng Kwan-Ming; Wang Ning; Siu Kayu; Feng Yibin; Tong Yao

    2009-01-01

    Bear bile has been used in Traditional Chinese Medicine (TCM) for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Techn...

  10. Transient unbalance response of four multilobe journal bearings

    Science.gov (United States)

    Allaire, P. E.; Li, D. F.; Choy, K. C.

    1979-01-01

    This work carries out an analysis of the transient response of four multilobe journal bearings (elliptical, offset, three-lobe, and four-lobe) subject to unbalance both below and above the linearized stability thresholds for the bearings. It extends the work of a previous paper on a balanced rotor in the same four bearing types. Transient orbits, bearing forces, and a numerical fast Fourier transform analysis of the orbits are presented. A comparison of bearing forces above the stability threshold for each bearing indicates that the elliptical bearing has the most violent whirl vibration amplitudes, while the offset bearing exhibits the least amount of subsynchronous vibration.

  11. Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

    Science.gov (United States)

    Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

    2014-01-01

    We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears. PMID:24477675

  12. All Polar Bear Critical Habitat Combined

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This layer shows all categories of polar bear critical habitat combined into one overall polygon. This polygon includes the following critical habitat types: 1)...

  13. Telemetry techniques used on Kodiak brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a study on the techniques used to monitor the movements of Kodiak brown bears instrumented with radio transmitters. Methods...

  14. Bear Lake-Minidoka - Phragmites Control

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Bear Lake: Phragmites patches were sprayed on the refuge & north of the lake proper. Minidoka: patches along the Snake River & Lake Walcott were treated...

  15. Failure tests of laminated rubber bearings

    International Nuclear Information System (INIS)

    Three different types of rubber bearing - natural rubber bearing (NRB), lead-rubber bearing (LRB), and high-damping rubber bearing (HRB) - were tested up to failure under various combinations of axial and shear forces. The test results are summarized as follows: 1) Offset shear strain greatly affects tensile behavior and failure. 2) Axial stress or strain does not so greatly affect shear behavior and failure. 3) The characteristics of NBR and LRB are almost independent of strain rate, but those of HRB depend greatly on it. 4) Cyclic loading affects large-deformation behavior and failure to some extent. 5) failure limits which include the interaction between axial stress and shear strain were quantitatively evaluated. 6) A lead plug of LRB has no bad influence on failure. These will be very useful for developing an ultimate response prediction technique, which is necessary to establish rational design philosophy of base isolation systems for FBR plants. (author)

  16. Mercury biomagnification in polar bears ( Ursus maritimus)

    Science.gov (United States)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  17. LIGHT-WEIGHT LOAD-BEARING STRUCTURE

    DEFF Research Database (Denmark)

    2009-01-01

    the core (3) of strong concrete. The invention also relates to a method of casting of light-weight load-bearing structures (1) with optimized compression zone (2) where one or more channels, grooves, ducts, pipes and/or hoses (5) formed in the load-bearing structure (1) serves as moulds for moulding......The invention relates to a light-weight load-bearing structure (1) with optimized compression zone (2), where along one or more compression zones (2) in the structure (1) to be cast a core (3) of strong concrete is provided, which core (3) is surrounded by concrete of less strength (4) compared to...... one or more cores (3) of strong concrete in the light-weight load-bearing structure (1)....

  18. Ceramic Rail-Race Ball Bearings

    Science.gov (United States)

    Balzer, Mark A.; Mungas, Greg S.; Peters, Gregory H.

    2010-01-01

    Non-lubricated ball bearings featuring rail races have been proposed for use in mechanisms that are required to function in the presence of mineral dust particles in very low-pressure, dry environments with extended life. Like a conventional ball bearing, the proposed bearing would include an inner and an outer ring separated by balls in rolling contact with the races. However, unlike a conventional ball bearing, the balls would not roll in semi-circular or gothic arch race grooves in the rings: instead, the races would be shaped to form two or more rails (see figure). During operation, the motion of the balls would push dust particles into the spaces between the rails where the particles could not generate rolling resistance for the balls

  19. Novel nano bearings constructed by physical adsorption

    Science.gov (United States)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  20. Cavitation Peening of Aerospace Bearings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-value bearings are a critical part of the safety, reliability, cost and performance of modern aircraft. A typical passenger jet will have 100 to 175 high-valve...

  1. Polar bear research in Alaska, spring 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  2. Polar bear research in Alaska, spring 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  3. The polar bear and its protection

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — No census has been made of the polar bear population and indeed the general movements of the animals within their range are poorly known. At present it is not...

  4. Bearings for the HFIR control plates

    International Nuclear Information System (INIS)

    Recent accelerated wear of HFIR bearings seems to be a more advanced stage of the situation encountered in 1967. The latest observations are in agreement with the hypothesis that high-frequency impact loads at a 300 angle on these bearings are the apparent basic cause of their short life. In view of the limited possibilities for change at this stage of HFIR operation, the region of best payoff seems to be an increase in the load-carrying area at some acceptable sacrifice of low rolling friction. On this basis three types of bearings are proposed for test--two of these are journal types and one is a slider type. The next planned shutdown for major parts replacement provides an opportunity to test these modified bearing types in the HFIR under full mechanical operating conditions but without nuclear operation. The program is recommended for consideration and adoption. (U.S.)

  5. Gauge Measures Large Spherical Bearing Surfaces

    Science.gov (United States)

    Davis, George L.

    1992-01-01

    Radius of spherical portion of surface computed from reading of depth gauge. Measuring tool calibrated by applying it to reference spherical surface of known radius. Used onsite, so unnecessary to ship bearings to laboratory for examination by computerized test equipment.

  6. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Science.gov (United States)

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. PMID:26803551

  7. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus).

    Science.gov (United States)

    Cronin, Matthew A; MacNeil, Michael D

    2012-01-01

    Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. We used previously published genotype data for 8 microsatellite DNA loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life-history characteristics that distinguish polar bears and brown bears as different species with little or no gene flow among extant populations. PMID:23125409

  8. Spectral properties and identification of aerostatic bearings

    Institute of Scientific and Technical Information of China (English)

    Jan Kozánek; Ladislav P(u)st

    2011-01-01

    Modified rotor kit BentlyNevada was used for dynamic characteristics measurements of new developed aerostatic bearings. Mathematical model of these bearings is considered as linear. Model was identified with the help of harmonic force excitation independently from the speed of journal rotation. The stiffness and damping matrices were identified for different air inlet pressures. The calculated spectral properties allow to determine the stability boundary for suitable variation of model parameters.

  9. Flywheel energy storage with superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.; Lynds, Jr., Lahmer; Hull, John R.

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  10. Partial Lubrification of Full Cylindrical Bearings

    OpenAIRE

    Capriz, Gianfranco; Cimatti, Giovanni

    1981-01-01

    the phenomenon of cavitation in bearings is often studied under the assumption that the pressure and the pressure gradient both vanish along the unknown boundary of the cavitation bubble. However, such conditions (often namend after Swift and Stieber) may be inconsistent with mass conservation. The discrepancy is particularly striking when the case of long bearings is studied within the so called Sommerfeld approximation. Therefore a complete analysis of the Sommerfeld case is carried out her...

  11. Surface layer characterisation of bearing rings

    OpenAIRE

    S.J. Skrzypek; M. Goły

    2007-01-01

    austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in bearing rings and following measurements of residual stresses were carried out as well. The bearing elements were made of 100Cr6 steel and they were smoothed and grinded.Design/methodology/approach: Particular features of diffraction patterns like angle position; shape and intensity are used to characterize phase composition, residual micro and macro-stresses, crystallographic tex...

  12. Design of bearing structures of dwelling - house

    OpenAIRE

    Sodja, Urška

    2007-01-01

    Graduation thesis represents design of bearing structures of dwelling-house including materials and materials´ properties of bearing structures. Self weight, imposed load, snow, and wind are determinated regarding EC1. Static calculation of building is divided to design of timber, reinforced concrete elements and control of resistance of walls. Summary contains earthquake rules for simple masonry buildings. Enclosure contains plans for positions of slaps and reinforces.

  13. Rotordynamics and bearing design of turbochargers

    Science.gov (United States)

    Chen, Wen Jeng

    2012-05-01

    Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

  14. Rolling Bearing Life Prediction, Theory, and Application

    Science.gov (United States)

    Zaretsky, Erwin V.

    2013-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg- Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application.

  15. A circumpolar monitoring framework for polar bears

    Science.gov (United States)

    Vongraven, Dag; Aars, Jon; Amstrup, S.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Mike; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

    2012-01-01

    Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

  16. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  17. Noise reduction of rotating machinery by viscoelastic bearing supports

    NARCIS (Netherlands)

    Tillema, Hetzer Gido

    2003-01-01

    The demand for silent rolling bearing applications, such as electric motors and gearboxes, has resulted in an investigation of viscoelastic bearing supports. By placing a thin viscoelastic layer between the bearing outer ring and the surrounding structure, vibrations of the shaft-bearing arrangement

  18. Severity estimation of cracked shaft vibrations within fluid film bearings

    Science.gov (United States)

    Prabhu, B. S.; Sekhar, A. S.

    1995-07-01

    The equations of motion, with four degrees of freedom, taking into consideration the flexibility, damping and cross coupling of the fluid film bearings are derived for a cracked Jeffcott rotor supported on fluid film bearings. Dimensionless equations are developed for dynamic radial load, dynamic pressure developed in the fluid film bearings and coefficient of dissipation considering the journal vibrations in two harmonics; bearing fluid film stiffness and damping coefficients. These are applied to a cracked Jeffcott rotor supported on different types of bearings, i.e., cylindrical journal bearings, offset cylindrical bearings, tilting pad journal bearings and three-lobe bearings. Based on the allowable dynamic pressure developed in the fluid bearings, the severity of cracked shaft and allowable crack depths are estimated in this study. Measurement of dynamic pressure and dissipation for monitoring the crack growth is suggested. However, 2x vibration is the best indicator of cracks in the shafts.

  19. Bearing assemblies, apparatuses, and motor assemblies using the same

    Energy Technology Data Exchange (ETDEWEB)

    Sexton, Timothy N.; Cooley, Craig H.; Knuteson, Cody W.

    2015-12-29

    Various embodiments of the invention relate to bearing assemblies, apparatuses and motor assemblies that include geometric features configured to impart a selected amount of heat transfer and/or hydrodynamic film formation. In an embodiment, a bearing assembly may include a plurality of superhard bearing pads distributed circumferentially about an axis. At least some of the plurality of superhard bearing pads may include a plurality of sub-superhard bearing elements defining a bearing surface. At least some of the plurality of sub-superhard bearing elements may be spaced from one another by one or more voids to impart a selected amount of heat transfer and hydrodynamic film formation thereon during operation. The bearing assembly may also include a support ring that carries the plurality of superhard bearing pads. In addition, at least a portion of the sub-superhard bearing elements may extend beyond the support ring.

  20. Rotor-Bearing System Stability Performance Comparing Hybrid versus Conventional Bearings

    Directory of Open Access Journals (Sweden)

    Gomez-Mancilla Julio

    2005-01-01

    Full Text Available New closed-form expressions for calculating the linear stability thresholds for rigid and flexible Jeffcott systems and the imbalance response for a rotor supported on a hybrid bearing are presented. For typical bearings characteristics, expressions yield stability thresholds practically equal to those reported by Lund (1966. The hybrid bearing design has a single injection port whose location is so chosen to stabilize the bearing performance and to reduce the steady equilibrium attitude angle. Rotordynamics coefficients graphs for conventional and pressurized bearings, as functions of bearing equilibrium eccentricity and/or Sommerfeld number, are presented. Using the rotordynamics coefficients into the expressions for the corresponding velocity thresholds and the imbalance response, the system stability and vibration performances are estimated and analyzed. When comparing the Jeffcott flexible shaft supported on two journal bearings of the conventional type with the hybrid type, the results show a clear superiority of the pressurized design as far as stability behavior is concerned. Specifically for cases of flexible shafts with similar characteristics to those used in industry, the analysis shows that this design yields velocity thresholds 25%–40% higher compared to the conventional circular ones. Also this bearing displays nonlinear feeding pressure behavior, and it is capable of reducing the synchronous vibration amplitude in most speed ranges, except around the critical speed; moreover, for certain Jeffcott configurations the amplitude reduction can be substantial.

  1. 77 FR 59639 - Bear Lake National Wildlife Refuge, Bear Lake County, ID and Oxford Slough Waterfowl Production...

    Science.gov (United States)

    2012-09-28

    ... notice in the Federal Register (75 FR 35829; June 23, 2010). Bear Lake National Wildlife Refuge Bear Lake... Fish and Wildlife Service Bear Lake National Wildlife Refuge, Bear Lake County, ID and Oxford Slough... our draft comprehensive conservation plan and environmental assessment (Draft CCP/EA) for the...

  2. Fatigue Life Analysis of Rolling Bearings Based on Quasistatic Modeling

    OpenAIRE

    Wei Guo; Hongrui Cao; Zhengjia He; Laihao Yang

    2015-01-01

    Rolling bearings are widely used in aeroengine, machine tool spindles, locomotive wheelset, and so forth. Rolling bearings are usually the weakest components that influence the remaining life of the whole machine. In this paper, a fatigue life prediction method is proposed based on quasistatic modeling of rolling bearings. With consideration of radial centrifugal expansion and thermal deformations on the geometric displacement in the bearings, the Jones’ bearing model is updated, which can pr...

  3. An Advanced Microturbine System with Water-Lubricated Bearings

    OpenAIRE

    Susumu Nakano; Tadaharu Kishibe; Tomoaki Inoue; Hiroyuki Shiraiwa

    2009-01-01

    A prototype of the next-generation, high-performance microturbine system was developed for laboratory evaluation. Its unique feature is its utilization of water. Water is the lubricant for the bearings in this first reported application of water-lubricated bearings in gas turbines. Bearing losses and limitations under usage conditions were found from component tests done on the bearings and load tests done on the prototype microturbine. The rotor system using the water-lubricated bearings ach...

  4. Noise reduction of rotating machinery by viscoelastic bearing supports

    OpenAIRE

    Tillema, Hetzer Gido

    2003-01-01

    The demand for silent rolling bearing applications, such as electric motors and gearboxes, has resulted in an investigation of viscoelastic bearing supports. By placing a thin viscoelastic layer between the bearing outer ring and the surrounding structure, vibrations of the shaft-bearing arrangement can be isolated and damped in such a way that the radiated sound power is reduced. The ultimate goal of this research was to develop a design strategy for viscoelastic bearing supports resulting i...

  5. Method for changing removable bearing for a wind turbine generator

    Energy Technology Data Exchange (ETDEWEB)

    Bagepalli, Bharat Sampathkumaran (Niskayuna, NY); Jansen, Patrick Lee (Scotia, NY), Gadre; Aniruddha Dattatraya (Rexford, NY)

    2008-04-22

    A wind generator having removable change-out bearings includes a rotor and a stator, locking bolts configured to lock the rotor and stator, a removable bearing sub-assembly having at least one shrunk-on bearing installed, and removable mounting bolts configured to engage the bearing sub-assembly and to allow the removable bearing sub-assembly to be removed when the removable mounting bolts are removed.

  6. Assessing bear-human conflicts in the Yukon Territory

    OpenAIRE

    Lukie, Raechel Dawn

    2010-01-01

    Managing conflicts between bears and humans is vital for human safety and for the conservation of bears. This study investigated black bear (Ursus americanus) and grizzly bear (Ursus arctos) interactions with humans in 18 major communities of the Yukon Territory. I used an information theoretic approach to generate predictive models of the relative potential of bear-human interaction for the 9 conservation officer management regions in the Yukon Territory. I independently modeled interactions...

  7. Vascular injuries after bear attacks: Incidence, surgical challenges and outcome

    OpenAIRE

    Wani Mohd; Ahangar Abdul; Lone Gh; Lone Reyaz; Ashraf Hakeem; Dar Abdul; Bhat M; Singh Shyam; Bijli Akram; Irshad Ifat

    2011-01-01

    Background : Bear mauling is rarely reported in medical literature due to its rare occurrence. Present study was undertaken to describe the pattern and management of bear maul vascular injuries in Kashmir. Methods : Study of patients with bear maul vascular injury from 1st Jan 2004 to 31st Dec. 2008. Fifteen patients with bear maul vascular injury were studied. All patients of bear maul without vascular injury were excluded from the study. Results : Most of the patients were treated by revers...

  8. Aerial strip surveys of polar bears in the Barents Sea

    OpenAIRE

    Wiig, Øystein; Bakken, Vidar

    1990-01-01

    Aerial strip surveys of polar bears in the Barents Sea were performed by helicopter in winter 1987. The number of bears within 100 m on each side of the helicopter was counted. A total of 263.6 km2 was surveyed and 21 bears were counted. Most of the bears were found in the southern part of the area, which indicates that the southwestern ice edge area in the Barents Sea is a very important winter habitat for polar bears.

  9. ES and H-compatible lubrication for duplex bearings

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.G.

    1997-10-01

    Two ES and H-compatible lubricants (environment, safety, and health) for duplex bearing applications and one hybrid material duplex bearing were evaluated and compared against duplex bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in strong link mechanisms since 1974. Hybrid duplex bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, duplex bearings lubricated with sputtered MoS{sub 2} on races and retainers, and duplex bearings lubricated with electrophoretic deposited MoS{sub 2} were evaluated. Bearings with electrophoretic deposited MoS{sub 2} performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax. Hybrid bearings with silicon nitride balls performed worse than bearings lubricated with Vydax, but their performance would still be acceptable for most applications. Bearings lubricated with sputtered MoS{sub 2} on the races and retainers had varying amounts of film on the bearings. This affected the performance of the bearings. Bearings with a uniform coating performed to acceptable levels, but bearings with no visible MoS{sub 2} on the races and retainers did not perform as well as bearings with the other coatings. Unless process controls are incorporated in the sputtering process or the bearings are screened, they do not appear to be acceptable for duplex bearing applications.

  10. A Comparative Study on Surface-Enhanced Raman Spectra of Thymine onto Silver Colloids and Island Films%银胶和银岛膜上胸腺嘧啶的表面增强拉曼光谱对比研究

    Institute of Scientific and Technical Information of China (English)

    郭浩; 丁丽; 莫育俊

    2011-01-01

    Surface-enhanced Raman scattering (SERS) spectra of thymine obtained on silver colloids and island films were studied comparatively. The spectroscopic characterization showed that the molecule configuration of thymine hydrolyzed ion compound was transformed from keto-amino to enol-amino after adsorption. On either silver surface, the N(3)-deprotonated tautomer was favorable. Thymine adsorbed on the silver colloids surfaces as enolate through the 0(7) and N(3) atoms while through the 0(8) and N(3) atoms in the case of silver island films surfaces.%利用表面增强拉曼光谱对胸腺嘧啶在银胶和银岛膜上的吸附状态进行了对比研究.光谱分析表明,胸腺嘧啶吸附在银胶和银岛膜表面后其分子结构发生了互变异构,由原来的酮式结构变成了烯醇式结构.在银胶和银岛膜表面胸腺嘧啶主要以N(3)去质子化异构体的形式存在.胸腺嘧啶通过O(7)和N(3)倾斜地吸附在银胶颗粒表面,通过O(8)和N(3)倾斜地吸附在银岛膜表面.

  11. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    Science.gov (United States)

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  12. Powder metallurgy bearings for advanced rocket engines

    Science.gov (United States)

    Fleck, J. N.; Killman, B. J.; Munson, H.E.

    1985-01-01

    Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.

  13. On Controllable Elastohydrodynamic Fluid Film Bearings

    DEFF Research Database (Denmark)

    Haugaard, Martin Asger

    This thesis gives a theoretical description of the active tilting-pad journal bearing (ATPJB). It provides the qualified reader with the tools to model an ATPJB, while staying clear of pitfalls. The model is based on well known techniques and allows for local stability analyses, harmonic stationary...... are performed for a tilting-pad journal bearing (TPJB) and an ATPJB under static conditions, followed by a generalisation to dynamic conditions (transient as well as stationary harmonic). These analyses will be of interest to experimentalists, since they permit experiments performed on scaled down...... great care, since the addition of a control system may just as well harm rotor-bearing performance as improve it....

  14. Robust bearing estimation for 3-component stations

    Energy Technology Data Exchange (ETDEWEB)

    CLAASSEN,JOHN P.

    2000-02-01

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the inherent information in the arrival at every step of the process to achieve near-optimal results. In particular the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, and finally to apply bias corrections when calibration information is available to yield a single final estimate. The algorithm was applied to a small but challenging set of events in a seismically active region. It demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted from these findings.

  15. Big Bear Exploration Ltd. 1998 annual report

    International Nuclear Information System (INIS)

    During the first quarter of 1998 Big Bear completed a purchase of additional assets in the Rainbow Lake area of Alberta in which light oil purchase was financed with new equity and bank debt. The business plan was to immediately exploit these light oil assets, the result of which would be increased reserves, production and cash flow. Although drilling results in the first quarter on the Rainbow Lake properties was mixed, oil prices started to free fall and drilling costs were much higher than expected. As a result, the company completed a reduced program which resulted in less incremental loss and cash flow than it budgeted for. On April 29, 1998, Big Bear entered into agreement with Belco Oil and Gas Corp. and Moan Investments Ltd. for the issuance of convertible preferred shares at a gross value of $15,750,000, which shares were eventually converted at 70 cents per share to common equity. As a result of the continued plunge in oil prices, the lending value of the company's assets continued to fall, requiring it to take action in order to meet its financial commitments. Late in the third quarter Big Bear issued equity for proceeds of $11,032,000 which further reduced the company's debt. Although the company has been extremely active in identifying and pursuing acquisition opportunities, it became evident that Belco Oil and Gas Corp. and Big Bear did nor share common criteria for acquisitions, which resulted in the restructuring of their relationship in the fourth quarter. With the future of oil prices in question, Big Bear decided that it would change its focus to that of natural gas and would refocus ts efforts to acquire natural gas assets to fuel its growth. The purchase of Blue Range put Big Bear in a difficult position in terms of the latter's growth. In summary, what started as a difficult year ended in disappointment

  16. Conflict Bear Translocation: Investigating Population Genetics and Fate of Bear Translocation in Dachigam National Park, Jammu and Kashmir, India

    OpenAIRE

    Mukesh,; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth ‘conflict bears’ from different sit...

  17. Cationic ruthenium alkylidene catalysts bearing phosphine ligands

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2016-01-01

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bear-ing bulky phosphine ligands. Simple ligand exchange using silver(I) salts of non-coordinating or weakly coordinating anions pro-vided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported...

  18. A CAD approach to magnetic bearing design

    Science.gov (United States)

    Jeyaseelan, M.; Anand, D. K.; Kirk, J. A.

    1988-01-01

    A design methodology has been developed at the Magnetic Bearing Research Laboratory for designing magnetic bearings using a CAD approach. This is used in the algorithm of an interactive design software package. The package is a design tool developed to enable the designer to simulate the entire process of design and analysis of the system. Its capabilities include interactive input/modification of geometry, finding any possible saturation at critical sections of the system, and the design and analysis of a control system that stabilizes and maintains magnetic suspension.

  19. Wear Analysis of Wind Turbine Gearbox Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  20. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  1. Rotor/bearing system dynamic stiffness measurements

    Science.gov (United States)

    Muszynska, A.

    1985-01-01

    Sweep perturbation testing as used in Modal Analysis when applied to a rotating machine has to take into consideration the machine dynamic state of equilibrium at its operational rotative speed. This stands in contrasts to a static equilibrium of nonrotating structures. The rotational energy has a significant influence on rotor dynamic characteristics. The best perturbing input for rotating machines is a forward or reverse rotating, circular force applied directly to the shaft. Determination of Dynamic Stiffness Characteristics of the rotor bearing system by nonsynchronous perturbation of a symmetric rotating shaft supported in one relatively rigid and one oil lubricated bearing.

  2. Bear Lake Basin : History, geology, biology, people

    OpenAIRE

    Palacios, Patsy; Luecke, Chris; Robinson, Justin

    2007-01-01

    Bear Lake is a large, deep lake located on the border of Utah and Idaho in Rich County Utah and Bear Lake County Idaho. It was formed through seismic activity along a fault on the eastern side of the lake. Tectonic shifts of the plates along this fault resulted in a lake basin that is over 200 ft deep along the eastern shore with a gradual slope to the western shore. The lake water has high concentrations of calcium carbonate because of high levels of evaporation typical of this semi-arid ...

  3. ACS air bearing test-bed design

    OpenAIRE

    Glitt, Sascha

    2010-01-01

    This thesis is about the construction and design of a new air bearing test-bed to verify the programmed ACS attitude control algorithm and to validate the ACS MATLAB/SimuLink¬ model of NPSAT1, the second small satellite currently under development at the Naval Postgraduate School Space Systems Academic Group. The software was already verified and validated using a comparable air bearing test-bed. But due to changes in hardware from commercial magnetic torque rods to custom, NPS-built, magneti...

  4. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    Directory of Open Access Journals (Sweden)

    David Fraser

    2013-09-01

    Full Text Available The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing.

  5. On the Design of Tilting-Pad Thrust Bearings

    DEFF Research Database (Denmark)

    Heinrichson, Niels

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...... geometries are given. Parallel-step bearings theoretically have smaller friction coefficients than tilting-pad bearings. A design of a tilting-pad bearing is suggested which combines the benefits of the two types of bearings in a tilting-pad bearing with inlet pockets. This design results in a substantial...

  6. Lubricant replacement in rolling element bearings for weapon surety devices

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

    1996-05-01

    Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

  7. Extended Life Testing of Duplex Ball Bearings

    Science.gov (United States)

    Mobley, Jeffrey; Robertson, Michael; Hodges, Charles

    2016-01-01

    Sierra Nevada Corporation’s Space Systems performed bearing life testing for the Scan Mirror Motor/Encoder Assembly (SMMA), part of the Scan Mirror Assembly on-board the Aerosol Polarimetry Sensor (APS) on the NASA Glory Spacecraft. The baseline bearing life test duration extended beyond the launch date for the Glory Spacecraft; a risk that the program was willing to undertake with the understanding that if any anomalies or failures occurred before the required life was achieved, then the mission objectives or operating profile could be modified on orbit to take those results into account. Even though the Glory Spacecraft failed to reach orbit during its launch in March of 2011, the bearing life testing was continued through a mutual understanding of value between Sierra Nevada Corporation and our customer; with a revised goal of testing to failure rather than completing a required number of life cycles. Life testing thus far has not only exceeded the original mission required life, but has also exceeded the published test data for Cumulative Degradation Factor (CDF) from NASA/CR-2009-215681. Many lessons were learned along the way regarding long life testing. The bearing life test has been temporarily suspended due to test support equipment issues.

  8. Angular-momentum-bearing modes in fission

    International Nuclear Information System (INIS)

    The angular-momentum-bearing degrees of freedom involved in the fission process are identified and their influence on experimental observables is discussed. The excitation of these modes is treated in the ''thermal'' limit, and the resulting distributions of observables are calculated. Experiments demonstrating the role of these modes are presented and discussed. 61 refs., 12 figs

  9. Bearings fault detection using inference tools

    OpenAIRE

    Prieto, Miguel Delgado; Roura, Jordi Cusidó i; Martínez, Jose Luis Romeral

    2011-01-01

    The most used electric machine in the industry is the Induction Motor (IM), due to its simplicity and reduced cost. The analysis of the origin of IMs failures exhibits that the bearings are the major source of fault, and even a common cause of degradation in other kinds of motors as Permanent Magnet Synchronous Machines.

  10. The economics of roadside bear viewing

    Science.gov (United States)

    Richardson, Leslie; Rosen, Tatjana; Gunther, Kerry; Schwartz, Chuck

    2014-01-01

    Viewing bears along roadside habitats is a popular recreational activity in certain national parks throughout the United States. However, safely managing visitors during traffic jams that result from this activity often requires the use of limited park resources. Using unique visitor survey data, this study quantifies economic values associated with roadside bear viewing in Yellowstone National Park, monetary values that could be used to determine whether this continued use of park resources is warranted on economic grounds. Based on visitor expenditure data and results of a contingent visitation question, it is estimated that summer Park visitation would decrease if bears were no longer allowed to stay along roadside habitats, resulting in a loss of 155 jobs in the local economy. Results from a nonmarket valuation survey question indicate that on average, visitors to Yellowstone National Park are willing to pay around $41 more in Park entrance fees to ensure that bears are allowed to remain along roads within the Park. Generalizing this value to the relevant population of visitors indicates that the economic benefits of allowing this wildlife viewing opportunity to continue could outweigh the costs of using additional resources to effectively manage these traffic jams.

  11. Thermo-hydrodynamic lubrication in hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the thermo-hydrodynamic and the thermo-elasto-hydrodynamic lubrication. The algorithms are methodically detailed and each section is thoroughly illustrated.

  12. Weak and strong nonlinearities in magnetic bearings

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav

    2004-01-01

    Roč. 39, č. 7 (2004), s. 779-795. ISSN 0094-114X R&D Projects: GA ČR GA101/00/1471; GA AV ČR IBS2076301 Institutional research plan: CEZ:AV0Z2076919 Keywords : weak nonlinearitiy * strong nonlinearity * magnetics bearings Subject RIV: BI - Acoustics Impact factor: 0.605, year: 2004

  13. Experimental investigation of gas aerostatic bearings

    Czech Academy of Sciences Publication Activity Database

    Steinbauer, P.; Šika, Z.; Kozánek, Jan; Šimek, J.

    2008-01-01

    Roč. 3, - (2008), s. 769-776. ISSN 1335-2393 R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * experimental identification * measurement Subject RIV: BI - Acoustics

  14. Surface layer characterisation of bearing rings

    Directory of Open Access Journals (Sweden)

    S.J. Skrzypek

    2007-11-01

    Full Text Available austenite. Theoretical calculation of residual macro-stresses due to volume fraction of transformed austenite in bearing rings and following measurements of residual stresses were carried out as well. The bearing elements were made of 100Cr6 steel and they were smoothed and grinded.Design/methodology/approach: Particular features of diffraction patterns like angle position; shape and intensity are used to characterize phase composition, residual micro and macro-stresses, crystallographic texture, lattice parameter, defects density and crystalline size.Findings: Machining by micro-deformation causes microstructural changes i.e. mechanically induced phase transformation of retained austenite and residual macrostresses. E.g. grinding cased tension and small compression whereas the mechanical smoothing of bearing rings caused high compresive residual stresses about -713 MPa.Research limitations/implications: For precise interpretation of differences between following results needs another investigations: i.e. measurement of retained austenite and residual stresses in rings after heat treatment before any mechanical treatment.Practical implications: The non-destructive character and large number of structural informations contained in diffraction pattern are the beneficial feature of diffraction methods. Therefore they have potential ability in application to technological operations and to diagnostic during fatigue.Originality/value: The non-destructive structure characterisation of surface layers for various kinds of bearing rings can be powerful method in surface characterization and in quality control. This results contribute in general relations between microstructure and properties.

  15. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    Directory of Open Access Journals (Sweden)

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.

  16. Load-Bearing Capacity of Roof Trusses

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Damkilde, Lars; Munch-Andersen, J.

    2004-01-01

    structural systems such as roof trusses are established and statistical characteristics of the load bearing capacity are determined. The results show that there is a significant increase in the characteristic (nominal) value and a reduction in the coefficient of variation (COV) for typical loads such as...

  17. Grievous Temporal and Occipital Injury Caused by a Bear Attack

    OpenAIRE

    Sampath Chandra Prasad; Nikhil Dinaker Thada; Pallavi Rao; Smitha Rani Thada; Kishore Chandra Prasad

    2013-01-01

    Bear attacks are reported from nearly every part of the world. The chance of a human encountering a bear increases as the remote bear territory diminishes. The sloth bear is one of the three species of bears found in India, which inhabits the forests of India and its neighboring countries. Here we describe a teenager who came to us with a critical injury involving the face, temporal and occipital bones inflicted by a sloth bear attack. He underwent a temporal exploration, facial nerve decompr...

  18. Computing Operating Characteristics Of Bearing/Shaft Systems

    Science.gov (United States)

    Moore, James D.

    1996-01-01

    SHABERTH computer program predicts operating characteristics of bearings in multibearing load-support system. Lubricated and nonlubricated bearings modeled. Calculates loads, torques, temperatures, and fatigue lives of ball and/or roller bearings on single shaft. Provides for analysis of reaction of system to termination of supply of lubricant to bearings and other lubricated mechanical elements. Valuable in design and analysis of shaft/bearing systems. Two versions of SHABERTH available. Cray version (LEW-14860), "Computing Thermal Performances Of Shafts and Bearings". IBM PC version (MFS-28818), written for IBM PC-series and compatible computers running MS-DOS.

  19. Rotor Bearing System Analysis Using the Transfer Matrix Method with Thickness Assumption of Disk and Bearing

    CERN Document Server

    Ghasemalizadeh, Omid; Sadeghi, Hossein; Ahmadian, Mohammad Taghi

    2013-01-01

    One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary conditions to the discretized system. In this paper the dynamics of a rotor-bearing system is analyzed, considering the gyroscopic effect. The thickness of the disk and bearings is also taken into account. Continuous model is used for shaft. Results Show that, the stiffness of the shaft and the natural frequencies of the system increase, while the amplitude of vibration decreases as a consequence of increasing the thickness of the bearing.

  20. Kenai Peninsula Brown Bear Studies : Report of the Interagency Brown Bear Study Team, 1986

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes work conducted during the 1986 field season on brown bear Ursus arctos from the Kenai Peninsula, Alaska. Ground surveys were conducted to...

  1. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    OpenAIRE

    David Fraser; Sara Dubois

    2013-01-01

    Simple Summary The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia. Residents of this small community were surveyed by phone twice over the following year, before and after government actions. This study aimed to understand local attitudes on how these bears should be managed and whether they differed from existing bea...

  2. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    OpenAIRE

    Zhengjun Tang; Daibiao Zhou; Chenwei Peng; Wenping Wu

    2015-01-01

    The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with prof...

  3. The thermodynamic properties of a new type catcher bearing used in active magnetic bearings system

    International Nuclear Information System (INIS)

    Normally a rotor levitated by active magnetic bearings (AMBs) system would rotate without contacting with any stator component, but the possibility still remains that the supporting force might lose temporarily or permanently, thus requiring the Catcher bearings (CBs) to provide backup protection in case of the failure of AMBs. A new type CB with two separate rolling element bearing series could have the speed distribution between the inner race and intermediate race according to certain ratio, in which the speed of each roller element bearing decreases with the limit speed of the whole CB increasing, offering high capability to sustain its initial rotation speed. Based on the theory of heat transfer, tribology, and rotor dynamics, this paper analyzes the thermal structure of double-decker catcher bearing (DDCB) and single-decker catcher bearing (SDCB), respectively. Through this structure, the thermal resistances and equations of heat transfer can be obtained. Then we calculate the friction heat and temperature distribution in the various CBs upon rotor's dropping on SDCB or DDCB, followed by the discussion on the CBs temperature rise's effects on lubrication conditions and rotor dynamics parameters. Finally various experiments are carried out to measure the temperature rise of different CBs. The results obtained validate the theoretical analysis and also provide main methods to reduce heat generation. Using DDCB is proved to be effective to reduce the temperature rise. - Highlights: • The DDCB is a more suitable catcher bearing for AMBs. • Compared to SDCB, using DDCB, the temperature rise can decrease in the same states. • A lower viscosity of lubricant may induce a lower temperature rise. • The inner raceway temperature of the first layer bearing is the highest. • Reducing the unbalance mass of the rotor is a method to decrease the temperature rise

  4. Biomechanical analysis of fixed bearing and mobile bearing total knee prostheses

    OpenAIRE

    Urwin, Samuel

    2014-01-01

    In total knee replacement (TKR) surgery, mobile bearing (MB) total knee prostheses were designed to more closely mimic the function of the normal knee than traditional fixed bearing (FB) designs by allowing axial mobility between the polyethylene insert and tibial tray. Despite the hypothetical benefits of the MB design, few studies have objectively analysed knee biomechanics during activities of daily living (ADLs) in the laboratory compared to FB designs. This thesis aimed to substantiate t...

  5. Population Parameters and Harvest Characteristics of Black Bears in Georgia

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes findings of black bear distribution and population trends throughout Georgia and evaluates black bear harvest trends from 1992 to 2002....

  6. Kodiak brown bear population on Kodiak Island, Alaska

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Methods and estimates of the Brown bear population on Kodiak Island. The total number of Kodiak Brown Bears on Kodiak Island has been estimated to be 1669. Three...

  7. Investigation of tribological and mechanical properties of metal bearings

    Indian Academy of Sciences (India)

    Bekir Sadik Ünlü

    2009-08-01

    Copper, aluminum and tin–lead based alloys are widely used as journal bearing materials in tribological applications. Bronze and brass are widely used as journal bearing materials for copper based alloys. Zamacs find applications as journal bearing materials for zinc based alloys, while duralumines are chosen as journal bearing materials for aluminum based alloys. In addition, white metals are widely used as journal bearing materials for tin–lead based alloys. These alloys ensure properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured by metals were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for a total of 150 min by using radial journal bearing wear test rig.

  8. Self-Bearing Motor-Generator for Flywheels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Self-bearing or ?bearingless? motors perform both motor and bearing support functions but such devices have not yet achieved speeds above 15,000 rpm. The innovation...

  9. Polar bear den survey, Arctic National Wildlife Range

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In conjunction with the Polar Bear Research Project being supervised by Mr. Jack Lentfer of the Bureau of Sport Fisheries and Wildlife two Polar Bear den surveys...

  10. Interchangeable Bearings for Profile and Weight Trade Studies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Air-Lock, Incorporated is proposing to design fully sealed shoulder and arm bearings with interchangeable bearing housings. The interchangeable housings shall be...

  11. Blade Bearing Friction Estimation of Operating Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    Blade root bearing on a wind turbine (WTG) enables pitching of blades for power control and rotor braking and is a WTG critical component. As the size of modern WTGs is constantly increasing, this leads to relatively less rigid bearings, more sensitive to deformations, thus WTG operational...... reliability can be increased by continuous monitoring of blade bearing. High blade bearing friction is undesirable, as it may be associated with excessive heating of the surfaces, damage and/or inefficient operation. Thus, continuous observation of bearing friction level is crucial for blade bearing health...... monitoring systems. A novel algorithm for online monitoring of bearing friction level is developed combining physical knowledge about pitch system dynamics with state estimator, i.e. observer theory and signal processing assuming realistic sensor availability. Results show estimation of bearing friction...

  12. A plan for the management of the Kodiak brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Management districts will be used as a tool to manage the population of bear on Kodiak Island. Theoretically, 204 bear may be taken off the refuge annually without...

  13. Shaft centre orbit for dynamically loaded radial bearings

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2002-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 Booker1 and described further in 1972 Booker2. Several authors have refined...... this method over the years. In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold´s equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In...... the mid seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in...

  14. The possibility of evaluating turbo-set bearing misalignment defects on the basis of bearing trajectory features

    Science.gov (United States)

    Rybczyński, Józef

    2011-02-01

    This paper presents the results of computer simulation of bearing misalignment defects in a power turbogenerator. This malfunction is typical for great multi-rotor and multi-bearing rotating machines and very common in power turbo-sets. Necessary calculations were carried out by the computer code system MESWIR, developed and used at the IFFM in Gdansk for calculating dynamics of rotors supported on oil bearings. The results are presented in the form of a set of journal and bush trajectories of all turbo-set bearings. Our analysis focuses on the vibrational effects of displacing the two most vulnerable machine bearings in horizontal and vertical directions by the maximum acceptable range calculated with regard to bearing vibration criterion. This assumption required preliminary assessment of the maximum values for the permissible bearing dislocations. We show the relations between the attributes of the particular bearing trajectories and the bearing displacements in relation to their base design position. The shape and dimensions of bearing trajectories are interpreted based on the theory of hydrodynamic lubrication of oil bearings. It was shown that the relative journal trajectories and absolute bush trajectories carry much important information about the dynamic state of the machine, indicating also the way in which bearings are loaded. Therefore, trajectories can be a source of information about the position and direction of bearing misalignments. This article indicates the potential of using trajectory patterns for diagnosing misalignment defects in rotating machines and suggests including sets of trajectory patterns to the knowledge base of a machine diagnostic system.

  15. Rotor stability estimation with competing tilting pad bearing models

    Science.gov (United States)

    Cloud, C. Hunter; Maslen, Eric H.; Barrett, Lloyd E.

    2012-05-01

    When predicting the stability of rotors supported by tilting pad journal bearings, it is currently debated whether or not the bearings should be represented with frequency dependent dynamics. Using an experimental apparatus, measurements of pad temperatures, unbalance response and stability are compared with modeling predictions for two tilting pad bearing designs. Predictions based on frequency dependent tilting pad bearing dynamics exhibited significantly better correlation with the stability measurements than those assuming frequency independent dynamics.

  16. Dynamic behaviour of ball bearing applications with constrained damping layers

    OpenAIRE

    Tillema, Hetzer G.

    2001-01-01

    Rolling bearing noise has become an aspect of increasing importance for the performance of rotating machinery, like electric motors and gearboxes. Generally, two aspects are important with regard to bearing noise, i.e. the transmission characteristics and the vibration generation characteristics. A potential source of vibrations are for example manufacturing imperfections of the different bearing components. Damping of bearing vibrations is enhanced by the lubrication film between the rolling...

  17. Stiffness calculation and application of spline-ball bearing

    Science.gov (United States)

    Gu, Bo-Zhong; Zhou, Yu-Ming; Yang, De-Hua

    2006-12-01

    Spline-ball bearing is widely adopted in large precision instruments because of its distinctive performance. For the sake of carrying out detail investigation of a full instrument system, practical stiffness formulae of such bearing are introduced with elastic contact mechanics, which are successfully applied for calculating the stiffness of the bearing used in astronomical telescope. Appropriate treatment of the stiffness of such bearing in the finite element analysis is also discussed and illustrated.

  18. Passive axial stabilization of a magnetic radial bearing by superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Marinescu, M.; Marinescu, N. (Ing.-Buro f. Magnettechnik, Mailander Str.19, D-6000 Frankfurt/M. 70 (DE)); Tenbrink, J.; Krauth, H. (Vacuumschmelze GmbH, Gruner Weg 37, D-6450 Hanau (DE))

    1989-09-01

    Contactless bearings for high-speed operation can be constructed using passive magnet systems, which inherently need a second, active bearing for their stabilization. Completely passive bearings only can be obtained using diamagnetic materials. This study deals with the axial stabilization of magnetic radial bearings using a permanent magnet/superconductor system. Using finite element calculation procedures it is shown that axial forces of up 3000 N and stiffnesses of up to 400 N/mm may be achieved.

  19. Active Magnetic Bearings – Magnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision......Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  20. Static Load Distribution in Ball Bearings

    Science.gov (United States)

    Ricci, Mario

    2010-01-01

    A numerical procedure for computing the internal loading distribution in statically loaded, single-row, angular-contact ball bearings when subjected to a known combined radial and thrust load is presented. The combined radial and thrust load must be applied in order to avoid tilting between inner and outer rings. The numerical procedure requires the iterative solution of Z + 2 simultaneous nonlinear equations - where Z is the number of the balls - to yield an exact solution for axial and radial deflections, and contact angles. Numerical results for a 218 angular-contact ball bearing have been compared with those from the literature and show significant differences in the magnitudes of the ball loads, contact angles, and the extent of the loading zone.

  1. An Evershed type superconducting flywheel bearing

    Energy Technology Data Exchange (ETDEWEB)

    Cansiz, A.; Campbell, A.M.; Coombs, T.A

    2003-07-15

    The objective of this work is to develop a bearing using high temperature superconductors (HTSs) for use in an energy storage flywheel. The experimental apparatus includes a cylindrical rotor levitated with the Evershed design in which the majority of the levitation force is provided by a permanent magnet arrangement and the stabilization of the system is achieved by HTS elements. The design characteristics and dynamics of the bearing associated with the rotor part are presented. The instrumentation measures the out of balance force and magnetomechanical stiffness associated with the rotor. A study of the rotational losses was performed using free spin down experiments associated with magnetic field variation measurements. The results are consistent with the loss being caused by hysteresis in the superconductor due to magnet inhomogeneity.

  2. An Evershed type superconducting flywheel bearing

    International Nuclear Information System (INIS)

    The objective of this work is to develop a bearing using high temperature superconductors (HTSs) for use in an energy storage flywheel. The experimental apparatus includes a cylindrical rotor levitated with the Evershed design in which the majority of the levitation force is provided by a permanent magnet arrangement and the stabilization of the system is achieved by HTS elements. The design characteristics and dynamics of the bearing associated with the rotor part are presented. The instrumentation measures the out of balance force and magnetomechanical stiffness associated with the rotor. A study of the rotational losses was performed using free spin down experiments associated with magnetic field variation measurements. The results are consistent with the loss being caused by hysteresis in the superconductor due to magnet inhomogeneity

  3. Active Magnetic Bearings – Magnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... the work is the characterization of magnetic forces by using two experimental different experimental approaches. Such approaches are investigated and described in details. A special test rig is designed where the 4 poles - AMB is able to generate forces up to 1900 N. The high precision...... characterization of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input...

  4. Radioactivity and the French uranium bearing minerals

    International Nuclear Information System (INIS)

    This special issue of Regne Mineral journal is entirely devoted to the French uranium mining industry. It comprises 4 parts dealing with: the uranium mining industry in France (history, uranium rush, deposits, geologic setting, prosperity and recession, situation in 1998, ore processing); radioactivity and the uranium and its descendants (discovery, first French uranium bearing ores, discovery of radioactivity, radium and other uranium descendants, radium mines, uranium mines, atoms, elements and isotopes, uranium genesis, uranium decay, isotopes in an uranium ore, spontaneous fission, selective migration of radionuclides, radon in mines and houses, radioactivity units, radioprotection standards, new standards and controversies, natural and artificial radioactivity, hazards linked with the handling and collecting of uranium ores, conformability with radioprotection standards, radioactivity of natural uranium minerals); the French uranium bearing minerals (composition, crystal structure, reference, etymology, fluorescence). (J.S.)

  5. Mechatronics Applied to Fluid Film Bearings: Towards More Efficient Machinery

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier

    Film Bearings: Towards more Efficient Machinery" was aimed at improving the state of the art regarding the usage of fluid film bearings as "smart" machine elements. Specifically, this project dealt with a tilting pad journal bearing design that features a controllable lubrication system, capable...

  6. 14 CFR 73.5 - Bearings; radials; miles.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Bearings; radials; miles. 73.5 Section 73.5 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRSPACE SPECIAL USE AIRSPACE General § 73.5 Bearings; radials; miles. (a) All bearings and radials in this...

  7. PROVIDING SERVICEABILITY OF STRUCTURAL BEARING TYPES FOR ROADWAY BRIDGES

    Directory of Open Access Journals (Sweden)

    R. I. Polyuga

    2010-03-01

    Full Text Available In the article the description of structural bearing types for roadway bridges and their classification is given. Special attention is paid to effective bearings with elastomeric materials – rubber, pot, spherical ones. Characteristic defects of structural bearings and demands of serviceability are noticed.

  8. 14 CFR 71.7 - Bearings, radials, and mileages.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Bearings, radials, and mileages. 71.7 Section 71.7 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... REPORTING POINTS § 71.7 Bearings, radials, and mileages. All bearings and radials in this part are true...

  9. 24 CFR 3285.202 - Soil classifications and bearing capacity.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Soil classifications and bearing... Soil classifications and bearing capacity. The soil classification and bearing capacity of the soil must be determined before the foundation is constructed and anchored. The soil classification...

  10. 49 CFR 230.103 - Tender roller bearing journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender roller bearing journal boxes. 230.103... Locomotives and Tenders Running Gear § 230.103 Tender roller bearing journal boxes. Tender roller bearing journal boxes shall be maintained in a safe and suitable condition....

  11. Temperature Distribution and Scuffing of Tapered Roller Bearing

    Institute of Scientific and Technical Information of China (English)

    WANG Ailin; WANG Jiugen

    2014-01-01

    In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

  12. 77 FR 73967 - Drawbridge Operation Regulation; Bear Creek, Dundalk, MD

    Science.gov (United States)

    2012-12-12

    ... Regulation; Bear Creek, Dundalk, MD'' in the Federal Register (77 FR 5201). The rulemaking concerned would... SECURITY Coast Guard 33 CFR Part 117 RIN 1625-AA09 Drawbridge Operation Regulation; Bear Creek, Dundalk, MD... highway bridge at Wise Avenue across Bear Creek, mile 3.4, between Dundalk and Sparrows Point, MD....

  13. Mechanical design problems associated with turbopump fluid film bearings

    Science.gov (United States)

    Evces, Charles R.

    1990-01-01

    Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

  14. Analyzing the use of pins in safety bearings

    DEFF Research Database (Denmark)

    da Fonseca, Cesar A. L. L.; Weber, Hans I.; Fleischer, Philip F.;

    2015-01-01

    A new concept for safety bearings is analyzed: useful in emergency situations, it shall protect the bearing from destruction by the use of pins which impact with a disc, both capable of good energy dissipation. Results of work in progress are presented by validating partial stages of the...... the bearing....

  15. Bearing pad to pressure tube contact simulation

    International Nuclear Information System (INIS)

    Thermal creep strain deformation is a very important pressure tube failure mechanism. During a postulated LOCA (loss of coolant accident) with failure of emergency core injection sys- tem (ECIS), the fuel cladding temperature rapidly increases and the pressure tube becomes completely dry in a few seconds after flow stagnation occurs. Subsequently, the pressure tube circumference is heated by thermal radiation except at the spots where the bearing pads are in direct contact with the pressure tube. Therefore, the localized hot spots are developed on the pressure tube's inner surface under the bearing pads. The main objective of this paper is to evaluate the local thermal-mechanical deformation of a pressure tube in a CANDU reactor and to investigate the fuel channel integrity under localized contact between bearing pad and pressure tube. Furthermore, the mechanistic models are validated against the experimental works per- formed at WRL (Whiteshell research laboratory). Calculations are performed using the finite element method in which the heat, thermal mechanical and creep strain equations are solved, simultaneously. According to the experimental set up, the heat conduction from bearing pads to the inner surface of the pressure tube with appropriate convective and radiation boundary conditions has been simulated. Furthermore, the thermal creep strain deformation has been obtained for when the pressure tube is still under operational condition. It is observed that the pressure tube thermal strain will occur if sufficient high temperature is reached however, depending on the severity of flow degradation in the fuel channel, these localized hot spots could represent a potential creep strain failure of the pressure tube. Whether the pressure tube would fail at these hot spots before contacting the calandria tube depends on the localized temperature and experienced pressure transients. Sensitivity analysis is performed in order to evaluate the contact conductance, the

  16. Motion of rotor supported on aerodynamic bearings

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Šimek, J.; Kozánek, Jan

    Praha : Institute of Thermomechanics AS CR, v. v. i., 2007 - (Zolotarev, I.), s. 235-236 ISBN 978-80-87012-06-2. [Engineering Mechanics 2007: national conference with international participation. Svratka (CZ), 14.05.2007-17.05.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : rotor dynamics * aerodynamic bearing * tilting pad s Subject RIV: BI - Acoustics

  17. Mutual interaction of two aerodynamic bearings

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Kozánek, Jan

    Lodz : Department of Automatics and Biomechanics Technical University of Lodz, 2007, s. 387-394. ISBN 978-83-924382-9-8. [Conference on Dynamical Systems - Theory and Applications /9./. Lodz (PL), 17.12.2007-20.12.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerodynamic bearing * evolutive systems * numerical solution Subject RIV: BI - Acoustics

  18. Sensorless Control of Axial Magnetic Bearings

    Science.gov (United States)

    Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.

  19. Existence of equilibria in articulated bearings

    Science.gov (United States)

    Buscaglia, G.; Ciuperca, I.; Hafidi, I.; Jai, M.

    2007-04-01

    The existence of equilibrium solutions for a lubricated system consisting of an articulated body sliding over a flat plate is considered. Though this configuration is very common (it corresponds to the popular tilting-pad thrust bearings), the existence problem has only been addressed in extremely simplified cases, such as planar sliders of infinite width. Our results show the existence of at least one equilibrium for a quite general class of (nonplanar) slider shapes. We also extend previous results concerning planar sliders.

  20. Determinattion of aerostatic journal bearing dynamic properties

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Šimek, J.; Steinbauer, P.; Neusser, Z.

    Praha: Ústav termomechaniky AV ČR, v. v. i., 2008 - (Pešek, L.), s. 161-168 ISBN 978-80-87012-10-9. [Dynamika strojů 2008. Praha (CZ), 05.02.2008-06.02.2008] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * stiffness and damping coefficients * identification Subject RIV: BI - Acoustics

  1. Low-Wear Ball-Bearing Separator

    Science.gov (United States)

    Hawkinson, Elden L.

    1991-01-01

    Proposed ball-bearing separator for use in cryogenic pump stronger and more resistant to wear. Consists of molded plastic-and-metal composite ring imbued with solid lubricant and containing embedded metal ring. Obtains combination of strength and lubricity. Before molding and machining, ring includes tooling portion for handling and indexing. Molded composite blend of PTFE and fluorinated ethylene/propylene (FEP) filled with brass and bronze powder and molybdenum disulfide powder.

  2. Friction and wear of HPSN bearing materials

    International Nuclear Information System (INIS)

    Silicon nitride-based ceramics are used as high-performance materials for roller bearings. Its low specific gravity (about one-third that of ball-bearing steel), retention of strength at high temperature and corrosion resistance make Si3N4 ideal for this application. The first study of hot-pressed silicon nitride (HPSN) was made by Baumgartner. Later works were reviewed by Cranmer. Most previous work was related to the evaluation of HPSN in contact with itself. In this paper, the authors present work on wear and friction of HPSN and its composites in contact with ball-bearing steel. HPSN was made by sintering a nitrogen-rich Si3N4 liquid phase. The effect of sintering aids on the wear behavior of HPSN and its composites was investigated. The composites were made by adding either a high-temperature lubricating material, e.g., hexagonal boron nitride (BN) or harder particulates, e.g., titanium carbide (TiC)

  3. Concurrent Initialization for Bearing-Only SLAM

    Directory of Open Access Journals (Sweden)

    Antoni Grau

    2010-03-01

    Full Text Available Simultaneous Localization and Mapping (SLAM is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes.

  4. Concurrent initialization for Bearing-Only SLAM.

    Science.gov (United States)

    Munguía, Rodrigo; Grau, Antoni

    2010-01-01

    Simultaneous Localization and Mapping (SLAM) is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range) cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras) in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes. PMID:22294884

  5. How Many Ore-Bearing Asteroids?

    CERN Document Server

    Elvis, Martin

    2013-01-01

    A simple formalism is presented to assess how many asteroids contain ore, i.e. commercially profitable material, and not merely a high concentration of a resource. I apply this formalism to two resource cases: platinum group metals (PGMs) and water. Assuming for now that only Ni-Fe asteroids are of interest for PGMs, then 1% of NEOs are rich in PGMs. The dearth of ultra-low delta-v (= US$1 B and the population of near-Earth objects (NEOs) larger than 100 m diameter is ~20,000 (Mainzer et al. 2011) the total population of PGM ore-bearing NEOs is roughly 10. I stress that this is a conservative and highly uncertain value. For example, an order of magnitude increase in PGM ore-bearing NEOs occurs if delta-v can as large as 5.7 km s-1. Water ore for utilization in space is likely to be found in ~1/1100 NEOs. NEOs as small as 18 m diameter can be water-ore-bodies because of the high richness of water (~20%) expected in ~25% of carbonaceous asteroids, bringing the number of water-ore-bearing NEOs to ~9000 out of th...

  6. Hydrolyzable polyureas bearing hindered urea bonds.

    Science.gov (United States)

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications. PMID:25406025

  7. AN INVESTIGATION OF MAGNETIC BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Gürcan SAMTAŞ

    2007-02-01

    Full Text Available The magnetic bearing consists of levitating a shaft so that it is free to rotate about its axis. The magnetic bearing has the advantages of being very quiet work and very cleanliness because there is no mechanical friction or lubricants. The shaft has two permanent magnets attached to it. These two magnets determine a straight line rotation axis of the rotor shaft. The magnets are radially levitated and centered within a cavity by a passive permanent magnetic field in the adding stator housing assembly. The levitation and centering of the shaft axially is stabilized by a closed loop electronic servo circuit that regulates an electromagnetic field in the stator housing that pushes and pulls on the shaft magnets. The rotor weight can be between one gram and forty five thousand, four hundred grams. In 1985, the first magnetic bearing was developed that it had used to applications of gas turbines and other compressors. In these days, they can be used by many applications which are Medical, Transportation, Machine and Tools Industry, Aerospace, Vacuum and Clean room Environments... etc.

  8. Conservation of brown bear in the Alps: space use and settlement behavior of reintroduced bears

    Science.gov (United States)

    Preatoni, Damiano; Mustoni, Andrea; Martinoli, Adriano; Carlini, Eugenio; Chiarenzi, Barbara; Chiozzini, Simonetta; Van Dongen, Stefan; Wauters, Luc A.; Tosi, Guido

    2005-11-01

    Large carnivores typically need large home ranges containing habitats patches of different quality. Consequently, their conservation requires habitat protection and management at the landscape scale. In some cases, reintroduction might be used to support remnant or restore extinct populations. This is the case for the brown bear ( Ursus arctos) in the Italian Alps. We monitored spacing behavior and settlement of reintroduced brown bears in Adamello-Brenta Natural Park, North-Italy, using radio-tracking. Habitat use, dispersion and survival were studied to evaluate the success of reintroduction and possible conflicts with man. All three males and five of seven females settled in the study area. Most bears roamed widely the first months after release, exploring the new habitat. Patterns of home range overlap between seasons and years revealed that home range use stabilized the year after first hibernation. Home ranges were larger in the mating season (May-July) than in spring or autumn. Home ranges varied between 34 and 1813 km 2 the year after release, but core-areas, where feeding activity was concentrated, were much smaller. Some bears had exclusive core-areas in summer and autumn, but most showed considerable core-area overlap with animals of the same and/or the opposite sex. Bears selected deciduous forests, mixed and conifer forests were used according to availability, and areas with anthropogenic disturbance were avoided. Most bears settled and some reproduced successfully at the release site, causing high initial population growth, suggesting that reintroduction can help to re-establish a brown bear population in the Italian Alps.

  9. Conflict bear translocation: investigating population genetics and fate of bear translocation in Dachigam National Park, Jammu and Kashmir, India.

    Science.gov (United States)

    Mukesh; Sharma, Lalit Kumar; Charoo, Samina Amin; Sathyakumar, Sambandam

    2015-01-01

    The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth 'conflict bears' from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears) returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape. PMID:26267280

  10. Conflict bear translocation: investigating population genetics and fate of bear translocation in Dachigam National Park, Jammu and Kashmir, India.

    Directory of Open Access Journals (Sweden)

    Mukesh

    Full Text Available The Asiatic black bear population in Dachigam landscape, Jammu and Kashmir is well recognized as one of the highest density bear populations in India. Increasing incidences of bear-human interactions and the resultant retaliatory killings by locals have become a serious threat to the survivorship of black bears in the Dachigam landscape. The Department of Wildlife Protection in Jammu and Kashmir has been translocating bears involved in conflicts, henceforth 'conflict bears' from different sites in Dachigam landscape to Dachigam National Park as a flagship activity to mitigate conflicts. We undertook this study to investigate the population genetics and the fate of bear translocation in Dachigam National Park. We identified 109 unique genotypes in an area of ca. 650 km2 and observed bear population under panmixia that showed sound genetic variability. Molecular tracking of translocated bears revealed that mostly bears (7 out of 11 bears returned to their capture sites, possibly due to homing instincts or habituation to the high quality food available in agricultural croplands and orchards, while only four bears remained in Dachigam National Park after translocation. Results indicated that translocation success was most likely to be season dependent as bears translocated during spring and late autumn returned to their capture sites, perhaps due to the scarcity of food inside Dachigam National Park while bears translocated in summer remained in Dachigam National Park due to availability of surplus food resources. Thus, the current management practices of translocating conflict bears, without taking into account spatio-temporal variability of food resources in Dachigam landscape seemed to be ineffective in mitigating conflicts on a long-term basis. However, the study highlighted the importance of molecular tracking of bears to understand their movement patterns and socio-biology in tough terrains like Dachigam landscape.

  11. Development and Evaluation of Titanium Space Suit Bearings

    Science.gov (United States)

    Rhodes, Richard; Battisti, Brian; Ytuarte, Ray, Jr.; Schultz, Bradley

    2016-01-01

    The Z-2 Prototype Planetary Extravehicular Space Suit Assembly is a continuation of NASA's Z series of spacesuits, designed with the intent of meeting a wide variety of exploration mission objectives, including human exploration of the Martian surface. Incorporating titanium bearings into the Z series space suit architecture allows us to reduce mass by an estimated 23 pounds per suit system compared to the previously used stainless steel bearing designs without compromising suit functionality. There are two obstacles to overcome when using titanium for a bearing race: 1) titanium is flammable when exposed to the oxygen wetted environment inside the space suit and 2) titanium's poor wear properties are often challenging to overcome in tribology applications. In order to evaluate the ignitability of a titanium space suit bearing, a series of tests were conducted at White Sands Test Facility that introduced the bearings to an extreme test profile, with multiple failures imbedded into the test bearings. The testing showed no signs of ignition in the most extreme test cases; however, substantial wear of the bearing races was observed. In order to design a bearing that can last an entire exploration mission (approximately 2 years), bearing test rigs were developed that allow for the quick evaluation of various bearing ball loads, ball diameters, lubricants, and surface treatments. This test data will allow designers to minimize the titanium bearing mass for a specific material and lubricant combination around a maximum contact stress that will allow the bearing to survive the life of an exploration mission. This paper reviews the current research and testing that has been performed on titanium bearing races to evaluate the use of such materials in an enriched oxygen environment and to optimize the bearing assembly mass and tribological properties to accommodate for the high bearing cycle life for an exploration mission.

  12. Unbalance Response Prediction for Rotors on Ball Bearings Using Speed- and Load-Dependent Nonlinear Bearing Stiffness

    Directory of Open Access Journals (Sweden)

    Fleming David P.

    2005-01-01

    Full Text Available Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus, an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work, bearing forces were calculated by COBRA-AHS, a recently developed rolling-element bearing analysis code. Bearing stiffness was found to be a strong function of bearing deflection, with higher deflection producing markedly higher stiffness. Curves fitted to the bearing data for a range of speeds and loads were supplied to a flexible rotor unbalance response analysis. The rotordynamic analysis showed that vibration response varied nonlinearly with the amount of rotor imbalance. Moreover, the increase in stiffness as critical speeds were approached caused a large increase in rotor and bearing vibration amplitude over part of the speed range compared to the case of constant-stiffness bearings. Regions of bistable operation were possible, in which the amplitude at a given speed was much larger during rotor acceleration than during deceleration. A moderate amount of damping will eliminate the bistable region, but this damping is not inherent in ball bearings.

  13. Late Quaternary cave bears and brown bears in Europe: implications for distribution, chronology, and extinction based on a multidisciplinary approach

    Science.gov (United States)

    Pacher, Martina

    2010-05-01

    Cave bear remains are one of the most numerous fossils found in European caves. Despite their frequency of occurrence, many aspects of cave bear palaeontology still remain poorly understood. New methodological approaches and ongoing studies led to controversial results and discussion about its taxonomy, palaeoecology, and final extinction. Are we dealing with one single or several species of cave bears? Was cave bear exclusively vegetarian or after all more omnivorous? Did he go extinct before or after the Late Glacial Maximum? Was cave bear restricted to Europe or did he also occur in Asia? Late Pleistocene brown bears, on the other hand, are often rare and little is known about the possible co-occurrence of cave and brown bears during the Late Pleistocene. Based on direct radiocarbon dates the distribution pattern of both, cave and brown bears is reconstructed during the Late Pleistocene in Europe. In addition, the reasons for the achieved pattern will be tested leading to the main question - why did cave bear become extinct while brown bears survived until today? To answer this question palaeobiological data of Late Pleistocene cave and brown bears will be tested against results from isotope analyses, while aDNA data may contribute to the question of distinct local population or even species of bears. The current state of evidence will be presented and on the basis of resulting pattern implications for further multi-disciplinary studies will be discussed.

  14. Bearing life in contaminated oil and oil passing into bearing for tapered roller bearing; Ensui koro jikuuke ni okeru ibutsu yuchu deno jumyo to kantsu yuryo

    Energy Technology Data Exchange (ETDEWEB)

    Asai, Y.; Oshima, H.; Sakamoto, K. [Koyo Seiko Co. Ltd., Osaka (Japan)

    1997-10-01

    In this paper a relationship between depth of dents, area of dents gathered and bearing life has been investigated for tapered roller bearings used in differential gear case. It is effective for the longer bearing life to reduce hard particles of Fe especially among several contaminations existing in the gear case. It is also effective to make oil level lower in the case from the view point for reduction of number of dents. 8 refs., 8 figs., 4 tabs.

  15. Experimental verification of an eddy-current bearing

    Science.gov (United States)

    Nikolajsen, Jorgen L.

    1989-01-01

    A new type of electromagnetic bearing was built and tested. It consists of fixed AC-electromagnets in a star formation surrounding a conducting rotor. The bearing works by repulsion due to eddy-currents induced in the rotor. A single bearing is able to fully support a short rotor. The rotor support is inherently stable in all five degrees of freedom. No feedback control is needed. The bearing is also able to accelerate the rotor up to speed and decelerate the rotor back to standstill. The bearing design and the experimentation to verify its capabilities are described.

  16. Stability of multi orifice active tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that the...... nature and magnitude of this influence depends on the rotor mass, preload factor and rotational speed. Furthermore, it is shown that assuming the bearing pads to be rigid can produce a substantial error. A rigid pad model will overpredict the stable range of the bearing, thus it may lead to failure if...

  17. On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2011-01-01

    modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... and drawbacks of this special kind of hybrid fluid film bearing....

  18. Relationship of rolling bearing stiffness with diameter of roller

    Institute of Scientific and Technical Information of China (English)

    郭茂林; 王刚; 张瑞

    2002-01-01

    The theoretical formula of roller bearing stiffness is induced and compared with its empirical formula.In the experience formula the stiffness of roller bearing has nothing to do with the roller diameter. The relation-ship of roller bearing stiffness with roller diameter was studied using Hz contacting theory. It is concluded thatconclusion in experience formula is only approximate result of data processing under special conditions, and therelation between stiffness of roller bearing and roller diameter must be taken into consideration while designingor selecting roller bearings.

  19. Sudden venting test of an emergency bearing for the magnet bearing type compound molecular pump

    International Nuclear Information System (INIS)

    The vacuum evacuation system for nuclear fusion reactors bears the role of exhausting hydrogen isotopes in large quantity together with helium continuously for long hours, and as the high vacuum pumps for this purpose, the mechanical pumps which can do continuous evacuation and decrease the quantity of staying radioactive tritium, such as turbo molecular pumps and compound molecular pumps, are promising. Because of the compatibility with tritium, oil lubrication is not desirable, accordingly, the pumps with ceramic rotating vanes and magnetic bearings are demanded. As a part of the development of a magnetic bearing type mechanical pump which can be used for nuclear fusion reactors, the compound molecular pump, in which emergency bearings were incorporated, was made for trial, and the test of sudden air intrusion was carried out, as the results, various knowledges were obtained. The constitution of the testing setup, and the test results are reported. When air was injected at the pressure rise of 3.3x104 Pa/s from exhaust port side, after about 2.5 s, the maximum lift of 4.2x103 N arose. When air was injected at the pressure rise of 2.7x105 Pa/s from the suction part side, after about 0.4s, the maximum lift of 6.9x103 N arose. In the air injection alternately from the suction port and exhaust port sides, the emergency bearings functioned normally in 10 times of the test. (K.I.)

  20. Rolling Bearing Steels - A Technical and Historical Perspective

    Science.gov (United States)

    Zaretsky, Erwin V.

    2012-01-01

    Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburizing grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with advanced lubrication technology, the potential improvements in bearing life can be as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability. The single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburized and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

  1. Analysis of thermoelastohydrodynamic performance of journal misaligned engine main bearings

    Science.gov (United States)

    Bi, Fengrong; Shao, Kang; Liu, Changwen; Wang, Xia; Zhang, Jian

    2015-05-01

    To understand the engine main bearings' working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic(TEHD) reaction on engine main bearings is investigated. The calculated method of main bearing's thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic(EHD) and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings.

  2. Research of Two Different Impulsive Faults of Rolling Element Bearing

    International Nuclear Information System (INIS)

    Fans and pumps are key machines in process industries such as petrochemical and petroleum industries. Their faults can be catastrophic and result in costly downtime. Bearing fault is almost the most common fault of fans and pumps as rolling element bearings are widely used in these machines. Hence, condition monitoring and diagnosis of bearings are important. Two different impulsive faults of bearings have been observed and studied in previous research. The first fault presents very clear impulsive symptom in envelope spectrum, but the bearing can work for a long time. The other fault shows relatively indistinct symptom, but the bearing will break down in a short time. To overcome the problems of inaccurate diagnosis, a combinational approach based on an impulsive energy indicator and traditional enveloping analysis is proposed in this paper. This approach discriminate these two faults well and can support the maintenance decision for the machines with rolling element bearings.

  3. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation...... performance of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure...

  4. Performance of passive target tracking using bearing-frequency and bearings of multiple arrays

    Institute of Scientific and Technical Information of China (English)

    DU Xuanmin; YAO Lan

    2002-01-01

    Two target motion analysis (TMA) methods using multi-dimension information are studied, one is TMA with bearing-frequency and the other is TMA with multiple arrays. The optimization algorithm combining Gauss-Newton (G-N) method with Levenberg-Marquardt(LM) method is applied to analyze the performance of target tracking with maximum likelihood estimation(MLE), and Monte Carlo experiments are presented. The results show that although the TMA with multi-dimension information have eliminated the maneuvers needed by conventional bearing-only TMA, but the application are not of universality.

  5. Method of recertifying a loaded bearing member

    Science.gov (United States)

    Allison, Sidney G. (Inventor)

    1992-01-01

    A method is described of recertifying a loaded bearing member using ultrasound testing to compensate for different equipment configurations and temperature conditions. The standard frequency F1 of a reference block is determined via an ultrasonic tone burst generated by a first pulsed phased locked loop (P2L2) equipment configuration. Once a lock point number S is determined for F1, the reference frequency F1a of the reference block is determined at this lock point number via a second P2L2 equipment configuration to permit an equipment offset compensation factor Fo1=((F1-F1a)/F1)(1000000) to be determined. Next, a reference frequency F2 of the unloaded bearing member is determined using a second P2L2 equipment configuration and is then compensated for equipment offset errors via the relationship F2+F2(Fo1)/1000000. A lock point number b is also determined for F2. A resonant frequency F3 is determined for the reference block using a third P2L2 equipment configuration to determine a second offset compensation factor F02=((F1-F3)/F1) 1000000. Next the resonant frequency F4 of the loaded bearing member is measured at lock point number b via the third P2L2 equipment configuration and the bolt load determined by the relationship (-1000000)CI(((F2-F4)/F2)-Fo2), wherein CI is a factor correlating measured frequency shift to the applied load. Temperature compensation is also performed at each point in the process.

  6. Flexure Based Linear and Rotary Bearings

    Science.gov (United States)

    Voellmer, George M. (Inventor)

    2016-01-01

    A flexure based linear bearing includes top and bottom parallel rigid plates; first and second flexures connecting the top and bottom plates and constraining exactly four degrees of freedom of relative motion of the plates, the four degrees of freedom being X and Y axis translation and rotation about the X and Y axes; and a strut connecting the top and bottom plates and further constraining exactly one degree of freedom of the plates, the one degree of freedom being one of Z axis translation and rotation about the Z axis.

  7. Bear Creek Project. Final environmental statement

    International Nuclear Information System (INIS)

    The Bear Creek Project consists of certain mining and milling operations involving uranium ore deposits located in Converse County, Wyoming. Mining of uranium from nine known ore bodies will take place over a period of ten years (estimated); a mill with a nominal capacity of 1000 tons per day of ore will be constructed and operated as long as ore is available. The waste material (tailings) from the mill, also produced at a rate of about 1000 tons per day, will be stored onsite in an impoundment. Environmental impacts and adverse effects are summarized

  8. Are organohalogen contaminants a bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Leifsson, PS;

    2006-01-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver......PBDE, polychlorinated biphenyl, and hexachlorocyclohexane concentrations. The lesions were consistent with those reported previously in highly OHC-contaminated Baltic seal populations and exposed laboratory animals. The renal lesions were a result of aging. However, based on the above statistical findings as well as...... health status among wildlife populations and humans relying on food resources that are contaminated with OHCs....

  9. Spectral properties and identification of aerostatic bearings

    Czech Academy of Sciences Publication Activity Database

    Kozánek, Jan; Půst, Ladislav

    2011-01-01

    Roč. 27, č. 1 (2011), s. 63-67. ISSN 0567-7718. [International Conference on Dynamical Systems - Theory and Applications /10./. Lodz, 07.12.2009-10.12.2009] R&D Projects: GA ČR GA101/09/1522 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerostatic bearing * identification * stiffness * damping coefficients Subject RIV: BI - Acoustics Impact factor: 0.860, year: 2011 http://www.springerlink.com/content/34l382r75g8wu716/

  10. Carbon Segregation of Bearing Steel Concasting Billet

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The formation mechanism of “white band” and central carbon segregation of high-carbon Cr bearing steel concasting billets are discussed in this paper. The maximum oxygen content in the steel produced by concasting process was 13x10-6 with an average oxygen content of 9.3x 10-6.Comparison of metallurgical quality and fatigue property between the concasting steel (CC) andingot casting steel (IC) showed that the carbon segregation (C/C0) in former steel was 0.92~1.10and its fatigue life was equal to that of the latter steel.

  11. Bearing capacity of mixed soil model

    Directory of Open Access Journals (Sweden)

    Mehdi Khodashenas Pelkoo

    2009-01-01

    Full Text Available The main objective of this research is improvement of red soil with addition of construction materials. This method could provide a scientific way to create a soil foundation with sufficient stability against geo-technical problems or instabilities. Laboratory tests have been conducted to assess the behavior of red soil, when amended with different types of gravels, soils and sand under compacted conditions with Optimum Moisture Content (OMC. Safe bearing capacity of all models, have been calculated to identify best and worst soil mixed model.

  12. Coronal properties of planet-bearing stars

    OpenAIRE

    Poppenhaeger, K.; Robrade, J.; Schmitt, J. H. M. M.

    2010-01-01

    Do extrasolar planets affect the activity of their host stars? Indications for chromospheric activity enhancement have been found for a handful of targets, but in the X-ray regime, conclusive observational evidence is still missing. We want to establish a sound observational basis to confirm or reject major effects of Star-Planet Interactions (SPI) in stellar X-ray emissions. We therefore conduct a statistical analysis of stellar X-ray activity of all known planet-bearing stars within 30pc di...

  13. Mechatronic stand for gas aerostatic bearing measurement

    Czech Academy of Sciences Publication Activity Database

    Steinbauer, P.; Kozánek, Jan; Neusser, Z.; Šika, Z.; Bauma, V.

    Berlin: Springer, 2008 - (Jablonski, R.; Turkowski, M.; Szewczyk, R.), s. 438-442 ISBN 978-3-540-73955-5. [International Symposium Mechatronics /7./. Waršava (PL), 19.09.2007-21.09.2007] R&D Projects: GA ČR GA101/06/1787 Institutional research plan: CEZ:AV0Z20760514 Keywords : gas aerostatic bearings * dynamical experiments * identification of stiffness and damping Subject RIV: BI - Acoustics http://www.springer.com/engineering/ robotics /book/978-3-540-73955-5

  14. Estimating Potential Effects of Hypothetical Oil Spills on Polar Bears

    Science.gov (United States)

    Amstrup, Steven C.; Durner, G.M.; McDonald, T.L.; Johnson, W.R.

    2006-01-01

    Much is known about the transport and fate of oil spilled into the sea and its toxicity to exposed wildlife. Previously, however, there has been no way to quantify the probability that wildlife dispersed over the seascape would be exposed to spilled oil. Polar bears, the apical predator of the arctic, are widely dispersed near the continental shelves of the Arctic Ocean, an area also undergoing considerable hydrocarbon exploration and development. We used 15,308 satellite locations from 194 radiocollared polar bears to estimate the probability that polar bears could be exposed to hypothetical oil spills. We used a true 2 dimensional Gausian kernel density estimator, to estimate the number of bears likely to occur in each 1.00 km2 cell of a grid superimposed over near shore areas surrounding 2 oil production facilities: the existing Northstar oil production facility, and the proposed offshore site for the Liberty production facility. We estimated the standard errors of bear numbers per cell with bootstrapping. Simulated oil spill footprints for September and October, the times during which we hypothesized effects of an oil-spill would be worst, were estimated using real wind and current data collected between 1980 and 1996. We used ARC/Info software to calculate overlap (numbers of bears oiled) between simulated oil-spill footprints and polar bear grid-cell values. Numbers of bears potentially oiled by a hypothetical 5912 barrel spill (the largest spill thought probable from a pipeline breach) ranged from 0 to 27 polar bears for September open water conditions, and from 0 to 74 polar bears in October mixed ice conditions. Median numbers oiled by the 5912 barrel hypothetical spill from the Liberty simulation in September and October were 1 and 3 bears, equivalent values for the Northstar simulation were 3 and 11 bears. In October, 75% of trajectories from the 5912 barrel simulated spill at Liberty oiled 9 or fewer bears while 75% of the trajectories affected 20 or

  15. Software Developed for Analyzing High- Speed Rolling-Element Bearings

    Science.gov (United States)

    Fleming, David P.

    2005-01-01

    COBRA-AHS (Computer Optimized Ball & Roller Bearing Analysis--Advanced High Speed, J.V. Poplawski & Associates, Bethlehem, PA) is used for the design and analysis of rolling element bearings operating at high speeds under complex mechanical and thermal loading. The code estimates bearing fatigue life by calculating three-dimensional subsurface stress fields developed within the bearing raceways. It provides a state-of-the-art interactive design environment for bearing engineers within a single easy-to-use design-analysis package. The code analyzes flexible or rigid shaft systems containing up to five bearings acted upon by radial, thrust, and moment loads in 5 degrees of freedom. Bearing types include high-speed ball, cylindrical roller, and tapered roller bearings. COBRA-AHS is the first major upgrade in 30 years of such commercially available bearing software. The upgrade was developed under a Small Business Innovation Research contract from the NASA Glenn Research Center, and incorporates the results of 30 years of NASA and industry bearing research and technology.

  16. Qualification of high damping seismic isolation bearings for the ALMR

    International Nuclear Information System (INIS)

    The Advanced Liquid Metal Reactor (ALMR) seismic isolation system consists of high damping steel-laminated elastomeric bearings. This type of bearing is used worldwide to isolate buildings and large critical components. A comprehensive testing program has been developed to qualify the use of this system for the ALMR. The program includes material characterization tests, various scale bearing tests, full-size bearing tests, shake table tests, and long-term aging tests. The main tasks and objectives of this program are described in the paper. Additionally, a detailed assessment of completed ALMR bearing test results will be provided. This assessment will be mainly based on half-scale bearing tests performed at the Earthquake Engineering Research Center (EERC) of the University of California at Berkeley and at the Energy Technology Engineering Center (ETEC). These tests were funded by the U.S. Department of Energy (DOE). Both static and dynamic tests were performed. Bearings with two types of end connections were tested: dowelled and bolted. The parameters examined will include the vertical, horizontal stiffness and damping of the bearings under different loading conditions up to failure. This will determine the available margins in the bearings above the design vertical load and horizontal displacement. Additionally, the self-centering capability of the bearings after an earthquake will be addressed. On the basis of these findings, recommendations can be made if necessary, to improve current manufacturing procedures, quality control, and procurement specifications. (author)

  17. Experimental study on bearing preload optimum of machine tool spindle

    International Nuclear Information System (INIS)

    An experimental study is conducted to investigate the possibility and the effect of temperature rise and vibration level of bearing by adjusting axial preloads and radial loads in spindle bearing test rig. The shaft of the test rig is driven by a motorized high speed spindle at the range of 0∼20000 rpm. The axial preloads and radial loads on bearings are controlled by using hydraulic pressure which can be adjusted automatically. Temperature rise and radial vibration of test bearings are measured by thermocouples and Polytec portable laser vibrometer PDV100. Experiment shows that the temperature rise of bearings is nonlinear varying with the increase of radial loads, but temperature rise almost increases linearly with the increase of axial preload and rotating speed. In this paper, an alternate axial preload is used for bearings. When the rotating speed passes through the critical speed of the shaft, axial preload of bearings will have a remarkable effect. The low preload could reduce bearing vibration and temperature rise for bearings as well. At the others speed, the high preload could improve the vibration performance of high speed spindle and the bearing temperature was lower than that of the constant pressure preload spindle.

  18. Electron Detachment as a Probe of Intrinsic Nucleobase Dynamics in Dianion-Nucleobase Clusters: Photoelectron Spectroscopy of the Platinum II Cyanide Dianion Bound to Uracil, Thymine, Cytosine and Adenine

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Ananya; Hou, Gao-Lei; Wang, Xue B.; Dessent, Caroline

    2015-08-05

    We report the first low-temperature photodetachment photoelectron spectra of isolated gas-phase complexes of the platinum II cyanide dianion bound to nucleobases. These systems are model systems for understanding platinum-complex photodynamic therapies, and knowledge of the intrinsic photodetachment properties is crucial for understanding their broader photophysical properties. Well-resolved, distinct peaks are observed in the spectra consistent with the complexes where the Pt(CN)42- moiety is largely intact. The adiabatic electron detachment energies for the dianion-nucleobase complexes are measured to be between 2.39-2.46 eV. The magnitudes of the repulsive Coulomb barriers of the complexes are estimated to be between 1.9 and 2.1 eV, values that are lower than for the bare Pt(CN)42- dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photodetachment spectra of the four nucleobase-dianion complexes, and also in the 266 nm spectra of the Pt(CN)42-∙thymine and Pt(CN)42-∙adenine complexes. The selective excitation of these features in the 266 nm spectra is attributed to one-photon excitation of [Pt(CN)42-∙T]* and [Pt(CN)42-∙A]* long-lived excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment signals. We attribute the resonant electron detachment bands observed here for Pt(CN)42-∙T and Pt(CN)42-∙A but not for Pt(CN)42-∙U and Pt(CN)42-∙C to fundamental differences in the individual nucleobase photophysics following 266 nm excitation. This indicates that the Pt(CN)42- dianion in the Pt(CN)42-∙M clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase disaplys a long-lived excited state.

  19. Non-fuel bearing hardware melting technology

    International Nuclear Information System (INIS)

    Battelle has developed a portable hardware melter concept that would allow spent fuel rod consolidation operations at commercial nuclear power plants to provide significantly more storage space for other spent fuel assemblies in existing pool racks at lower cost. Using low pressure compaction, the non-fuel bearing hardware (NFBH) left over from the removal of spent fuel rods from the stainless steel end fittings and the Zircaloy guide tubes and grid spacers still occupies 1/3 to 2/5 of the volume of the consolidated fuel rod assemblies. Melting the non-fuel bearing hardware reduces its volume by a factor 4 from that achievable with low-pressure compaction. This paper describes: (1) the configuration and design features of Battelle's hardware melter system that permit its portability, (2) the system's throughput capacity, (3) the bases for capital and operating estimates, and (4) the status of NFBH melter demonstration to reduce technical risks for implementation of the concept. Since all NFBH handling and processing operations would be conducted at the reactor site, costs for shipping radioactive hardware to and from a stationary processing facility for volume reduction are avoided. Initial licensing, testing, and installation in the field would follow the successful pattern achieved with rod consolidation technology

  20. Load bearing capacity of degraded nuclear piping

    International Nuclear Information System (INIS)

    Integrity assessment of piping components with postulated cracks is important for safe and reliable operation of power plants. While various equations and methods are available for prediction of the load bearing capacity of pipes and elbows, it is very important to choose the correct equation and method whose predictions are consistent, safe but not too conservative with respect to the experimental results. Towards this goal, a comprehensive Component Integrity Assessment Program was initiated under a joint MPA-BARC collaborative program where a large number of austenitic and ferritic pipes and elbows of nominal diameter of 50-400 mm with various crack configurations and sizes were tested. These test results along with results of previous tests were analysed with various available limit load equations present and also with the R6 method. Based on the comparison of these test results and predictions, the correct equation and method are recommended to reliably predict the load bearing capacity of flawed pipes and elbows reliably. (authors)

  1. Individual effects of seasonal changes, visitor density, and concurrent bear behavior on stereotypical behaviors in captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Kelly, Krista R; Harrison, Michelle L; Size, Daniele D; MacDonald, Suzanne E

    2015-01-01

    Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy. PMID:24933263

  2. Detection of bearing damage by statistic vibration analysis

    Science.gov (United States)

    Sikora, E. A.

    2016-04-01

    The condition of bearings, which are essential components in mechanisms, is crucial to safety. The analysis of the bearing vibration signal, which is always contaminated by certain types of noise, is a very important standard for mechanical condition diagnosis of the bearing and mechanical failure phenomenon. In this paper the method of rolling bearing fault detection by statistical analysis of vibration is proposed to filter out Gaussian noise contained in a raw vibration signal. The results of experiments show that the vibration signal can be significantly enhanced by application of the proposed method. Besides, the proposed method is used to analyse real acoustic signals of a bearing with inner race and outer race faults, respectively. The values of attributes are determined according to the degree of the fault. The results confirm that the periods between the transients, which represent bearing fault characteristics, can be successfully detected.

  3. A Review on Prognosis of Rolling Element Bearings

    Directory of Open Access Journals (Sweden)

    N.S. Jammu

    2011-10-01

    Full Text Available Bearings are amongst the frequently encountered components to be found in rotating machinery. Though inexpensive, their failure can interrupt the production in a plant causing unscheduled downtime and production losses. So the bearing prognosis plays a significant role in reducing plant down time and enhanced operation safety, by estimating the Remaining Useful Life (RUL of damaged bearing. Admitting the importance of bearing prognosis, this literature reviewattempts to summarize various techniques, methods and models used in the prognosis of bearing till date. The definition of bearing prognosis is discussed in the beginning, followed by classification ofvarious prognostic methods, review of methods used by various investigators in this research domain and concluding the topic with the summary of future research directions.

  4. On the future of controllable fluid film bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar

    2011-01-01

    This work gives an overview of the theoretical and experimental achievements of mechatronics applied to fluid film bearings. Compressible and uncompressible fluids are addressed. Rigid and elastic (deformable) bearing profiles are investigated. Hydraulic, pneumatic, magnetic and piezoelectric...... controllable fluid film bearings is to improve the overall machine performance by: controlling the lateral vibration of rigid and flexible rotating shafts; modifying bearing dynamic characteristics, such as stiffness and damping properties; increasing the rotational speed ranges by enhancing damping and...... eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing start-up torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable fluid film bearings can act as “smart” machine components and be applied to...

  5. Wear fault diagnosis of an emulsion pump crank bearing

    Institute of Scientific and Technical Information of China (English)

    HAN Xiao-ming; DU Chang-long; ZHANG Yong-zhong; TIE Zhan-xu

    2008-01-01

    The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism.The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the bearing axis was obtained. As the crank bearing gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank bearing can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.

  6. Improvement of design technique of track machines bodies bearing structures

    Directory of Open Access Journals (Sweden)

    Bogdan TOVT

    2012-01-01

    Full Text Available The paper is devoted to improvement of design technique of track machines bodies bearing structures. The review and analysis of state-of-the-art of the mathematical programming theory and the optimal designing are done. The numerical optimization procedure for track machines bodies bearing structures is proposed. The approbation of the proposed procedure is taken on structural optimization problems. Mathematical aspects of proposed procedure implementation are investigated, particularly the algorithm convergence and the sensitivity analysis of initial designs.Deflected mode of the ballast leveling machine SPZ-5/UA body bearing structure was investigated analytically (FEM study and experimentally (trial running inspection on durability. The necessity of optimization implementation for bodies bearing structures is substantiated. The rational design of track machine SPZ-5/UA bearing structure was obtained with the numerical optimization procedure proposed in the paper. The deflected mode of the body rational bearing structure was investigated.

  7. The R and D D's bearing test benches

    International Nuclear Information System (INIS)

    In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author)

  8. A Low Friction Thrust Bearing for Reciprocating Compressors

    OpenAIRE

    Nagata, Shuhei; Kousokabe, Hirokatsu; Sekiyama, Nobuya; Ono, Toshiaki

    2012-01-01

    A thrust bearing with a micro texture on its sliding surface that produces hydrodynamic pressure was developed for use in reciprocating compressors. Evaluation using an elemental friction test showed that its friction loss was 20–60 % lower than that of the current design. Measurement of the efficiency of a compressor with the developed thrust bearing showed that the coefficient of performance was 1.4 % higher than that of a compressor with a conventional thrust bearing.

  9. A magnetic bearing based on eddy-current repulsion

    Science.gov (United States)

    Nikolajsen, J. L.

    1987-01-01

    This paper describes a new type of electromagnetic bearing, called the Eddy-Current Bearing, which works by repulsion between fixed AC-electromagnets and a conducting rotor. The following advantages are expected: inherent stability, higher load carrying capacity than DC-electromagnetic bearings, simultaneous radial, angular and thrust support, motoring and generating capability, and backup mode of operation in case of primary power failure. A prototype is under construction.

  10. Suppression of Base Excitation of Rotors on Magnetic Bearings

    OpenAIRE

    Steven Marx; C. Nataraj

    2007-01-01

    This paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional, and differential feedback control. A four-degree-of-freedom model is used for the rotor system, and the bearings are ...

  11. Variable viscosity condition in the modeling of a slider bearing

    OpenAIRE

    Uprety, Kedar Nath; Mancas, Stefan C.

    2014-01-01

    To reduce tear and wear of machinery lubrication is essential. Lubricants form a layer between two surfaces preventing direct contact and reduce friction between moving parts and hence reduce wear. In this short letter the lubrication of two slider bearings with parallel and nonparallel is studied. First, we show that bearings with parallel plates cannot support any load. For bearings with nonparallel plates we are interested on how constant and temperature dependent viscosity affects the pro...

  12. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    OpenAIRE

    Nittmannová Ľubica; Magura Martin

    2016-01-01

    The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types ...

  13. Food availability and foraging near human developments by black bears

    Science.gov (United States)

    Merkle, Jerod A.; Robinson, Hugh S.; Krausman, Paul R.; Alaback, Paul B.

    2013-01-01

    Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

  14. The peculiarities of bear numbers dynamics in the Eastern Carpathians

    OpenAIRE

    Khoyetskyy, Pavlo

    2013-01-01

    There have been two periods of change in the dynamics of bear population in the Eastern Carpathians. The first period lasted over 50 years, starting in the late 1940s and ending in the year 2001. The second period started in the early 21st century. The bear population reached its maximum – of about 1100 individuals – in the early 1970s. Over 85% of recorded bear deaths have resulted from poaching.

  15. Household Portfolios and Risk Bearing over Age and Time

    OpenAIRE

    Alessandro Bucciol; Raffaele Miniaci

    2011-01-01

    We exploit the US Survey of Consumer Finances from 1998 to 2007 to study households’ portfolio risk bearing. We compare four alternative measures of risk, two based on a financial portfolio and two based on a broader portfolio also including – as illiquid assets – human capital, real estate, business wealth and related debt. The measures provide a different ranking of household risk bearing, but they consistently show that risk bearing fell after 2001, and it positively correlates with wealth...

  16. Spatial Distribution of Black Bear Incident Reports in Michigan.

    Directory of Open Access Journals (Sweden)

    Jamie E McFadden-Hiller

    Full Text Available Interactions between humans and carnivores have existed for centuries due to competition for food and space. American black bears are increasing in abundance and populations are expanding geographically in many portions of its range, including areas that are also increasing in human density, often resulting in associated increases in human-bear conflict (hereafter, bear incidents. We used public reports of bear incidents in Michigan, USA, from 2003-2011 to assess the relative contributions of ecological and anthropogenic variables in explaining the spatial distribution of bear incidents and estimated the potential risk of bear incidents. We used weighted Normalized Difference Vegetation Index mean as an index of primary productivity, region (i.e., Upper Peninsula or Lower Peninsula, primary and secondary road densities, and percentage land cover type within 6.5-km2 circular buffers around bear incidents and random points. We developed 22 a priori models and used generalized linear models and Akaike's Information Criterion (AIC to rank models. The global model was the best compromise between model complexity and model fit (w = 0.99, with a ΔAIC 8.99 units from the second best performing model. We found that as deciduous forest cover increased, the probability of bear incident occurrence increased. Among the measured anthropogenic variables, cultivated crops and primary roads were the most important in our AIC-best model and were both positively related to the probability of bear incident occurrence. The spatial distribution of relative bear incident risk varied markedly throughout Michigan. Forest cover fragmented with agriculture and other anthropogenic activities presents an environment that likely facilitates bear incidents. Our map can help wildlife managers identify areas of bear incident occurrence, which in turn can be used to help develop strategies aimed at reducing incidents. Researchers and wildlife managers can use similar mapping

  17. Design of load-bearing elements of a multiresidental building

    OpenAIRE

    Klopčič, gradbenik, Jure

    2012-01-01

    This thesis presents the design and analysis of load-bearing elements in a four storey multiresidental building according to current Eurocode standards for the design of building structures. Load-bearing elements, composed of monolith reinforced concrete, are slabs, separated walls, walls with openings and pillars. In the analysis of the load-bearing structure the influence of permanent and variable weight and also the impact of wind, snow and earthquake are considered. Detailed analysis of v...

  18. MOBILE TIBIAL POLYETHYLENE BEARING IN TOTAL KNEE ARTHROPLASTY

    OpenAIRE

    de Araújo Barros Cobra, Hugo Alexandre; da Palma, Idemar Monteiro

    2015-01-01

    Debris of polyethylene tibial bearings have been recognized as a major cause for the onset of the cascade of biological events leading to osteolysis and loosening of prosthetic components after total knee arthroplasty. Since then, research has been focused on alternative bearing surfaces in order to minimize the amount and rate of polyethylene wear off and, in doing so, increasing the survivorship rate for knee arthroplasties. One such option is to have a mobile tibial bearing allowing more c...

  19. Fatigue Crack Initiation and Propagation of Aluminum Alloy Bearings

    Institute of Scientific and Technical Information of China (English)

    CHENG Xian-Hua; MA Yan-Yan

    2004-01-01

    Observation of fatigue crack initiation and propagation during fatigue test in ALSn20Cu bearing has been presented. Journal center orbit, oil film pressure and stress distribution in alloy layer have been calculated and are taken as the basis for theoretically simulating the bearing fatigue process. It is found that the calculated results are in good accordance with the experimental results, which provides a feasible way for investigation of fatigue crack propagation process in the bearing.

  20. Incorporation of radioactive pyrimidic precursors into the deoxyribonucleic acids of Chlorella pyrenoidosa

    International Nuclear Information System (INIS)

    (2-14C) thymidine is incorporated into the nuclear and chloroplastic DNAs of Chlorella pyrenoidosa, strain Emerson. (me-14C) thymidine is incorporated into chloroplastic DNA, but never into nuclear DNA. The radioactivity is still found to be associated with thymine. When the cultures are supplied with (2-14C) uracil, both DNAs are radioactive and the radioactivity is found to be associated with thymine, cytosine, and, for the nuclear DNA, 5-methylcytosine. (2-14C) deoxycytidine is also incorporated into both DNAs, but their specific activity is very low. These results suggest that thymidine is specifically incorporated into chloroplastic DNA of the strain Emerson. In the case of the nuclear DNA, they suggest the existence of a thymidine demethylation mechanism, probably localized in the cytoplasm. (orig.)

  1. A MICRO TURBINE DEVICE WITH ENHANCED MICRO AIR-BEARINGS

    OpenAIRE

    Shan, X.-C.; Zhang, Qide; Sun, Y. F.; Maeda, R

    2006-01-01

    As part of progress in developing a micro gas turbine engine, this paper presents the design, fabrication and testing of a silicon-based micro turbine device, which is driven by compressed air. To improve its rotational speed and stability, the turbine device has enhanced journal air bearing and thrust air bearings. The thrust air bearings are utilized for supporting the rotor from both its top- and bottom- sides. The top thrust air bearing employs pump-in type spiral grooves, and the bottom ...

  2. Numerical Analysis of Nonlinear Rotor-bearing-seal System

    Institute of Scientific and Technical Information of China (English)

    CHENG Mei; MENG Guang; JING Jian-ping

    2008-01-01

    The system state trajectory, Poincaré maps, largest Lyapunov exponents, frequency spectra and bifurcation diagrams were used to investigate the non-linear dynamic behaviors of a rotor-bearing-seal coupled system and to analyze the influence of the seal and bearing on the nonlinear characteristics of the rotor system. Various nonlinear phenomena in the rotor-bearing-seal system, such as periodic motion, double-periodicmotion, multi-periodic motion and quasi-periodic motion were investigated. The results may contribute to a further understanding of the non-linear dynamics of the rotor-bearing-seal coupled system.

  3. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  4. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  5. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  6. Interaction of Reinforced Elastomeric Bearings in Bridge Construction

    Directory of Open Access Journals (Sweden)

    Nittmannová Ľubica

    2016-03-01

    Full Text Available The aim of this paper is to demonstrate the behavior of reinforced elastomeric bearings under various loads. They are made of special types of bearings. The experimental verification of these special bearings has been tested on various types of loading. The results of the experimental measurements are compared with the results of the numerical modeling and calculations according to the standard assumptions in STN EN 1337-3. In the conclusion, the results are summarized for the selected types of bearings.

  7. Wear Performance of Ceramic-On-Metal Hip Bearings

    OpenAIRE

    Jörn Reinders; Robert Sonntag; Christian Heisel; Tobias Reiner; Leo Vot; Jan Philippe Kretzer

    2013-01-01

    Ceramic-on-metal (CoM) bearings are considered to be a promising alternative to polyethylene-based bearings or hard-on-hard bearings (Ceramic-on-Ceramic (CoC) and Metal-on-Metal (MoM)). Although, CoM shows lower wear rates than MoM, in-vitro wear testing of CoM shows widely varying results. This may be related to limitations of wear-measuring methods. Therefore, the aim of this study was to improve the gravimetric measurement technique and to test wear behaviour of CoM bearings compared to Co...

  8. INVESTIGATION OF TRIBOLOGICAL PROPERTIES CuSn10 BEARING MATERIAL

    Directory of Open Access Journals (Sweden)

    Bekir Sadık ÜNLÜ

    2005-01-01

    Full Text Available Bronzes which copper based alloys is widely used because of properties physical, thermal and tribological as journal bearing material. This material that has tribological performance good conclusions gives at journal bearings. In this study, CuSn10 bronze that were manufactured journal bearings friction and wear properties has been examined and compared. SAE 1050 steel shaft has been used as counter abrader. Experiments have been carried out 10 N and 20 N loads, 750 and 1500 rpm, dry and lubricated conditions by using radial journal bearing wear test rig. As a results, high friction coefficient and weigh loss have been obtained at dry condition more than lubricated condition.

  9. Targeting Faulty Bearings for an Ocean Turbine Dynamometer

    Directory of Open Access Journals (Sweden)

    David J. Vendittis

    2013-01-01

    Full Text Available A real-time, vibrations-based condition monitoring method used to detect, localize, and identify a faulty bearing in an ocean turbine electric motor is presented in this paper. The electric motor is installed in a dynamometer emulating the functions of the actual ocean turbine. High frequency modal analysis and power trending are combined to assess the operational health of the dynamometer’s bearings across an array of accelerometers. Once a defect has been detected, envelope analysis is used to identify the exact bearing containing the defect. After a brief background on bearing fault detection, this paper introduces a simplified mathematical model of the bearing fault, followed with the signal processing approach used to detect, locate, and identify the fault. In the results section, effectiveness of the methods of bearing fault detection presented in this paper is demonstrated through processing data collected, first, from a controlled lathe setup and, second, from the dynamometer. By mounting a bearing containing a defect punched into its inner raceway to a lathe and placing an array of accelerometers along the length of lathe, the bearing fault is clearly detected, localized, and identified as an inner raceway defect. Through retroactively trending the data leading to the near-failure of one of the electric motors in the dynamometer, the authors identified a positive trend in energy levels for a specific frequency band present across the array of accelerometers and identify two bearings as possible sources of the fault.

  10. Accurately bearing measurement in non-cooperative passive location system

    International Nuclear Information System (INIS)

    The system of non-cooperative passive location based on array is proposed. In the system, target is detected by beamforming and Doppler matched filtering; and bearing is measured by a long-base-ling interferometer which is composed of long distance sub-arrays. For the interferometer with long-base-line, the bearing is measured accurately but ambiguously. To realize unambiguous accurately bearing measurement, beam width and multiple constraint adoptive beamforming technique is used to resolve azimuth ambiguous. Theory and simulation result shows this method is effective to realize accurately bearing measurement in no-cooperate passive location system. (authors)

  11. Numerical investigation of cavitation flow in journal bearing geometry

    Science.gov (United States)

    Riedel, M.; Schmidt, M.; Stücke, P.

    2013-04-01

    The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  12. Numerical investigation of cavitation flow in journal bearing geometry

    Directory of Open Access Journals (Sweden)

    Stücke P.

    2013-04-01

    Full Text Available The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

  13. Gene transcription in polar bears (Ursus maritimus) from disparate populations

    Science.gov (United States)

    Bowen, Lizabeth; Miles, A. Keith; Waters, Shannon C.; Meyerson, Randi; Rode, Karyn D.; Atwood, Todd C.

    2015-01-01

    Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

  14. Platelet function in brown bear (Ursus arctos compared to man

    Directory of Open Access Journals (Sweden)

    Särndahl Eva

    2010-06-01

    Full Text Available Abstract Background Information on hemostasis and platelet function in brown bear (Ursus arctos is of importance for understanding the physiological, protective changes during hibernation. Objective The study objective was to document platelet activity values in brown bears shortly after leaving the den and compare them to platelet function in healthy humans. Methods Blood was drawn from immobilized wild brown bears 7-10 days after leaving the den in mid April. Blood samples from healthy human adults before and after clopidogrel and acetylsalicylic acid administration served as control. We analyzed blood samples by standard blood testing and platelet aggregation was quantified after stimulation with various agonists using multiple electrode aggregometry within 3 hours of sampling. Results Blood samples were collected from 6 bears (3 females between 1 and 16 years old and from 10 healthy humans. Results of adenosine diphosphate, aspirin, and thrombin receptor activating peptide tests in bears were all half or less of those in humans. Platelet and white blood cell counts did not differ between species but brown bears had more and smaller red blood cells compared with humans. Conclusion Using three different tests, we conclude that platelet function is lower in brown bears compared to humans. Our findings represent the first descriptive study on platelet function in brown bears and may contribute to explain how bears can endure denning without obvious thrombus building. However, the possibility that our findings reflect test-dependent and not true biological variations in platelet reactivity needs further studies.

  15. Synchronous dynamics of a coupled shaft/bearing/housing system with auxiliary support from a clearance bearing: Analysis and experiment

    Science.gov (United States)

    Lawen, James L., Jr.; Flowers, George T.

    1995-01-01

    This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing synchronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified.

  16. Geomechanical Modeling of Gas Hydrate Bearing Sediments

    Science.gov (United States)

    Sanchez, M. J.; Gai, X., Sr.

    2015-12-01

    This contribution focuses on an advance geomechanical model for methane hydrate-bearing soils based on concepts of elasto-plasticity for strain hardening/softening soils and incorporates bonding and damage effects. The core of the proposed model includes: a hierarchical single surface critical state framework, sub-loading concepts for modeling the plastic strains generally observed inside the yield surface and a hydrate enhancement factor to account for the cementing effects provided by the presence of hydrates in sediments. The proposed framework has been validated against recently published experiments involving both, synthetic and natural hydrate soils, as well as different sediments types (i.e., different hydrate saturations, and different hydrates morphologies) and confinement conditions. The performance of the model in these different case studies was very satisfactory.

  17. Handling of tritium-bearing wastes

    International Nuclear Information System (INIS)

    The generation of nuclear power and reprocessing of nuclear fuel results in the production of tritium and the possible need to control the release of tritium-contaminated effluents. In assessing the need for controls, it is necessary to know the production rates of tritium at different nuclear facilities, the technologies available for separating tritium from different gaseous and liquid streams, and the methods that are satisfactory for storage and disposal of tritiated wastes. The intention in applying such control technologies and methods is to avoid undesirable effects on the environment, and to reduce the radiation burden on operational personnel and the general population. This technical report is a result of the IAEA Technical Committee Meeting on Handling of Tritium-bearing Effluents and Wastes, which was held in Vienna, 4 - 8 December 1978. It summarizes the main topics discussed at the meeting and appends the more detailed reports on particular aspects that were prepared for the meeting by individual participants

  18. Load Bearing Innovative Construction from Glass

    Science.gov (United States)

    Kalamar, R.; Eliášová, M.

    2015-11-01

    Glass plays an exceptional role in the modern architecture due to the optical properties and transparency. Structural elements from glass like beams, facades and roofs are relatively frequent in common practice [1]. Although glass has significantly higher compressive strength in comparison with tensile strength, load bearing glass elements are relatively rare. This opens up new opportunities for application of glass in such structures as transparent columns loaded by the axial force. This paper summarizes the experimental results of the tests on glass columns loaded by centric pressure, which were performed in the laboratories of the CTU in Prague, Faculty of Civil Engineering. The first set of experiments was composed of three specimens in a reduced scale 1:2 to verify real behaviour of the specimens with enclosed hollow cross-section. The main goal of the experiment was to determine force at the first breakage and consequently the maximal force at the collapse of this element.

  19. Mastication forces and implant-bearing surface.

    Science.gov (United States)

    Le Gall, M G; Lauret, J F; Saadoun, A P

    1994-01-01

    This article discusses the shift of emphasis in implantology from the phenomenon of osseointegration of implants to the accurate fabrication of the prosthesis, recognizing the implant/prosthesis unit as an actual replica rather than a replacement of the missing tooth. The study of kinetics with its succession of mandibular cycles is used to discuss the integration of mastication and occlusion. The importance of periimplant ligament in natural teeth is discussed, along with the impact of its absence on implant mobility. The impact of the bone types and the root surface architecture on the implant-bearing surface is presented along with the stress of the mastication forces. All these factors have to be considered in the treatment planning and effectively communicated to the laboratory. The learning objective of this article is to provide updated information in those areas for the reader. PMID:7488751

  20. Pooh Bear rock and Mermaid Dune

    Science.gov (United States)

    1997-01-01

    One of the two forward cameras aboard Sojourner imaged this area of Martian terrain on Sol 26. The large rock dubbed 'Pooh Bear' is at far left, and stands between four and five inches high. Mermaid Dune is the smooth area stretching horizontally across the top quarter of the image. The Alpha Proton X-Ray Spectrometer (APXS) instrument aboard Sojourner will be deployed on Mermaid Dune, and the rover will later use its cleated wheels to dig into it.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages and Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  1. Batch fabrication of carbon nanotube bearings

    International Nuclear Information System (INIS)

    Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes (MWNTs) can be used as a robust nanoscale motion enabling mechanism. Here, we report on a novel method suited for structuring large arrays of MWNTs into such nanobearings in a parallel fashion. By creating MWNT nanostructures with nearly identical electrical circuit resistance and heat transport conditions, uniform Joule heating across the array is used to simultaneously engineer the shell geometry via electric breakdown. The biasing approach used optimizes process metrics such as yield and cycle-time. We also present the parallel and piecewise shell engineering at different segments of a single nanotube to construct multiple, but independent, high density bearings. We anticipate this method for constructing electromechanical building blocks to be a fundamental unit process for manufacturing future nanoelectromechanical systems (NEMS) with sophisticated architectures and to drive several nanoscale transduction applications such as GHz-oscillators, shuttles, memories, syringes and actuators

  2. Toxicity of Magnetic Albumin Microspheres Bearing Adriamycin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Magnetic albumin microspheres bearing adriamycin (ADM-MAM) is a novel chemotherapeutic compound with site-specific drug delivery characteristics. The acute and subacute toxic tests of the compound, local irritating test and anaphylactic test were performed on mice and guinea pigs. The results showed there was no macroscopically and microscopically direct cytotoxic injuries of the compound to the animal organs or to the cells. The LD50 value of the compound was higher than that of the single used adriamycin, indicating that the compound was less toxic than the single adriamycin and quite safe in its therapeutic dosage. Furthermore, there was also no side effects or toxic reactions to be observed on clinical patients with advanced carcinoma or gastric cancer.

  3. Bear Creek Project. Draft environmental statement

    International Nuclear Information System (INIS)

    The Bear Creek Project consists of mining and milling operations involving uranium ore deposits located in Converse County, Wyoming. Mining of uranium from six known ore bodies will take place over ten years; a 1000 tons ore/day will be constructed and operated as long as ore is available. The tailings will be stored onsite in an impoundment. The project would convert 2700 acres from grazing use to mining/milling activities for about ten years. Mining would disturb a total of 1600 acres but, because of reclamation, the max acreage disturbed at any one time would be about 1000 acres, the average being about 650 acres. Dose rates were computed for an individual in a ranch house at the nearest ranch. Conditions for the protection of the environment are proposed. Possible environmental impacts evaluated cover air, land, water, soil, vegetation, wildlife, and community. A benefit-cost analysis is made

  4. GPU-BSM: a GPU-based tool to map bisulfite-treated reads.

    Directory of Open Access Journals (Sweden)

    Andrea Manconi

    Full Text Available Cytosine DNA methylation is an epigenetic mark implicated in several biological processes. Bisulfite treatment of DNA is acknowledged as the gold standard technique to study methylation. This technique introduces changes in the genomic DNA by converting cytosines to uracils while 5-methylcytosines remain nonreactive. During PCR amplification 5-methylcytosines are amplified as cytosine, whereas uracils and thymines as thymine. To detect the methylation levels, reads treated with the bisulfite must be aligned against a reference genome. Mapping these reads to a reference genome represents a significant computational challenge mainly due to the increased search space and the loss of information introduced by the treatment. To deal with this computational challenge we devised GPU-BSM, a tool based on modern Graphics Processing Units. Graphics Processing Units are hardware accelerators that are increasingly being used successfully to accelerate general-purpose scientific applications. GPU-BSM is a tool able to map bisulfite-treated reads from whole genome bisulfite sequencing and reduced representation bisulfite sequencing, and to estimate methylation levels, with the goal of detecting methylation. Due to the massive parallelization obtained by exploiting graphics cards, GPU-BSM aligns bisulfite-treated reads faster than other cutting-edge solutions, while outperforming most of them in terms of unique mapped reads.

  5. Study of a four Titled Pad Bearing

    Directory of Open Access Journals (Sweden)

    Ibrahim A. Mohsen

    2013-05-01

    Full Text Available This research deal with an analytical study of a four titled pad bearing. These pads are arranged around the journal. A computer program has been used to solve Reynolds equation numerically using the finite difference technique.            The results showed that, the non dimensional force is increased with the increase of the non dimensional load and the gradient of the curve is increased with the decrease of the ( ratio. while the gradient is decreased with the increase of the number of pads which gives less power absorption due to the decrease of the friction force.            Also the results showed  that the eccentricity ratio is in the range of (0.4-0.8 and the maximum attitude angle is (43o. The curve of the relation between the eccentricity ratio and the load number does not start from the zero.            It has been noticed that the increase of the friction factor cause an increase in Summerfield number and the curve gradient is increase with the decrease of the ( ratio. Also the gradient is increased for a fixed value of the ( ratio with the decrease of external load, where as the decrease of the ( ratio cause a decrease of the oil film thickness and this cause an increase of the shearing rate.             Finally, the oil flow rate is increased with the increase of the ( ratio and this would increased more with the increase of the number of pads for the same value of ( ratio which leads to a decrease of the bearing temperature and this maintain the same value of the oil film thickness due to maintaining the same viscosity for the lubricant.

  6. Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

    Science.gov (United States)

    Flowers, George T.

    1995-01-01

    Progress made in the current year is listed, and the following papers are included in the appendix: Steady-State Dynamic Behavior of an Auxiliary Bearing Supported Rotor System; Dynamic Behavior of a Magnetic Bearing Supported Jet Engine Rotor with Auxiliary Bearings; Dynamic Modelling and Response Characteristics of a Magnetic Bearing Rotor System with Auxiliary Bearings; and Synchronous Dynamics of a Coupled Shaft/Bearing/Housing System with Auxiliary Support from a Clearance Bearing: Analysis and Experiment.

  7. Gulf-Wide Information System, Environmental Sensitivity Index Bear Database, Geographic NAD83, LDWF (2001) [esi_bear_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains sensitive biological resource data for the Louisiana black bear in coastal Louisiana. Vector polygons represent occupied habitat for this...

  8. Ancestral Polymorphisms and Sex-Biased Migration Shaped the Demographic History of Brown Bears and Polar Bears

    OpenAIRE

    Shigeki Nakagome; Shuhei Mano; Masami Hasegawa

    2013-01-01

    Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA) and matrilineal mitochondrial DNA (mtDNA). Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA) or more than 14 times (mtDNA) larger population sizes than p...

  9. Ancestral polymorphisms and sex-biased migration shaped the demographic history of brown bears and polar bears.

    Directory of Open Access Journals (Sweden)

    Shigeki Nakagome

    Full Text Available Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA and matrilineal mitochondrial DNA (mtDNA. Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA or more than 14 times (mtDNA larger population sizes than polar bears and that polar bear lineage is derived from within brown bear diversity. In brown bears, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar bears across aDNA genes and mtDNA.

  10. Interference-Fit Life Factors for Roller Bearings

    Science.gov (United States)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2009-01-01

    The effect of hoop stresses in reducing cylindrical roller bearing fatigue life was determined for various classes of inner-ring interference fit. Calculations were performed for up to 7 fit classes for each of 10 bearing sizes. The hoop stresses were superimposed on the Hertzian principal stresses created by the applied radial load to calculate roller bearing fatigue life. A method was developed through a series of equations to calculate the life reduction for cylindrical roller bearings. All calculated lives are for zero initial internal clearance. Any reduction in bearing clearance due to interference fit would be compensated by increasing the initial (unmounted) clearance. Results are presented as tables and charts of life factors for bearings with light, moderate, and heavy loads and interference fits ranging from extremely light to extremely heavy for bearing accuracy class RBEC-5 (ISO class 5). Interference fits on the inner ring of a cylindrical roller bearing can significantly reduce bearing fatigue life. In general, life factors are smaller (lower life) for bearings running under light load where the unfactored life is highest. The various bearing series within a particular bore size had almost identical interference-fit life factors for a particular fit. The tightest fit at the high end of the tolerance band produces a life factor of approximately 0.40 for an inner-race maximum Hertz stress of 1200 MPa (175 ksi) and a life factor of 0.60 for an inner-race maximum Hertz stress of 2200 MPa (320 ksi). Interference fits also impact the maximum Hertz stress-life relation.

  11. Rotor Bearing System Analysis Using the Transfer Matrix Method with Thickness Assumption of Disk and Bearing

    OpenAIRE

    Ghasemalizadeh, Omid; Mirzaee, Mohammad Reza; Sadeghi, Hossein; Ahmadian, Mohammad Taghi

    2013-01-01

    One of the methods to find the natural frequencies of rotating systems is the application of the transfer matrix method. In this method the rotor is modeled as several elements along the shaft which have their own mass and moment of inertia. Using these elements, the entire continuous system is discretized and the corresponding differential equation can be stated in matrix form. The bearings at the end of the shaft are modeled as equivalent spring and dampers which are applied as boundary con...

  12. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    Science.gov (United States)

    Flowers, George T.; Xie, Huajun; Sinha, S. C.

    1995-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness, and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  13. Seasonal carbohydrate storage and mobilization in bearing and non-bearing pistachio (Pistacia vera) trees.

    Science.gov (United States)

    Spann, Timothy M; Beede, Robert H; Dejong, Theodore M

    2008-02-01

    We analyzed annual carbohydrate storage and mobilization of bearing ("on") and non-bearing ("off") 'Kerman' pistachio (Pistacia vera L.) trees growing on three different rootstocks. On all rootstocks, carbohydrate storage in shoots and branches of "on" and "off" trees was lowest following the spring growth flush. In "off" trees, stored carbohydrates increased and remained high after the initial growth flush. In "on" trees, stem carbohydrates increased temporarily in early summer, but were mobilized in mid-season during kernel fill, and then increased again after nut harvest. During the dormant season, the only substantial differences in carbohydrate storage between previously "on" and "off" trees were found in the roots of the weakest rootstock. The annual carbohydrate storage and mobilization pattern in canopy branches of heavily cropped pistachio trees appeared to be driven by carbohydrate demands related to nut development and untempered by tree vigor. Mobilization of carbohydrates from current-season and 1- and 2-year-old stem wood of "on" trees during the primary period of kernel fill corresponded with the period of inflorescence bud abscission. Thus, the alternate bearing pattern associated with inflorescence bud abscission in 'Kerman' pistachio may be a function of mid-season mobilization of stored carbohydrates in current-season stems resulting in stimulation of inflorescence bud abscission. PMID:18055431

  14. 19 CFR 133.21 - Articles bearing counterfeit trademarks.

    Science.gov (United States)

    2010-04-01

    ...: “The sample described as and provided pursuant to 19 CFR 133.21(d) was (damaged/destroyed/lost) during... 19 Customs Duties 1 2010-04-01 2010-04-01 false Articles bearing counterfeit trademarks. 133.21... Recorded Trademarks or Recorded Trade Names § 133.21 Articles bearing counterfeit trademarks....

  15. 36 CFR 7.80 - Sleeping Bear Dunes National Lakeshore.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Sleeping Bear Dunes National Lakeshore. 7.80 Section 7.80 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.80 Sleeping Bear Dunes...

  16. Permanent magnet design for high-speed superconducting bearings

    Science.gov (United States)

    Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

    1996-09-10

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs.

  17. Removal of radionuclides by analcime-bearing rocks

    International Nuclear Information System (INIS)

    The study of the removal of radionuclides (uranium, radium and thorium) in static conditions from aqueous solutions by analcime-bearing rocks and pure analcime was carried out. The high removal efficiency of all studied radionuclides by analcime-bearing rocks was determined. Analcime was efficient in removing of thorium only

  18. On the future of controllable fluid film bearings

    OpenAIRE

    Santos, Ilmar

    2011-01-01

    This work gives an overview of the theoretical and experimental achievements of mechatronics applied to fluid film bearings. Compressible and uncompressible fluids are addressed. Rigid and elastic (deformable) bearing profiles are investigated. Hydraulic, pneumatic, magnetic and piezoelectric actuators are used. The ideas of combining control techniques, informatics with hydrodynamic, thermo-hydrodynamic, elasto-hydrodynamic and thermo-elasto-hydrodynamic lubrication techniques are carefully ...

  19. Performance of an active electric bearing for rotary micromotors

    International Nuclear Information System (INIS)

    An electric bearing used to support a micromachined rotor of variable-capacitance motors was designed and tested in order to study the characteristics of this frictionless bearing. Electrostatic suspension of a ring-shaped rotor in five degrees of freedom is required to eliminate the mechanical bearing and thus the friction and wear between the rotor and the substrate. Bulk microfabrication-based glass/silicon/glass bonding is chosen for this device, allowing the fabrication of large area sense capacitors and rotor, which make the device potentially suitable for the development of an electrostatically suspended micromachined gyroscope. The device and its basic operating principle are described, as well as the dynamics of the rotor and basic design considerations of the electric bearing system. A theoretical relationship to relate the characteristics of a classical lag–lead compensator to the stiffness properties of the electric bearing is developed to explain the experimental bearing measurements. The experimental results of closed-loop frequency response, suspension stiffness and drive voltage effects are presented and discussed for the bearing operated initially in the atmospheric environment. The performance of a tri-axial electrostatic accelerometer has also been experimentally investigated on the prototype of the electric bearing system

  20. Peculiar Aspects of Rotor-Bearing Systems Vibrations

    Directory of Open Access Journals (Sweden)

    Radu Panaitescu-Liess

    2011-09-01

    Full Text Available The rotor-bearing systems are marked both by an asymmetrical stiffness and by important damping properties, which are causing instability in their rotating motion. The asymmetrical properties presented in this paper are displayed in the rotor motion preferential direction due to the damping internal forces mainly, and also to forces in slide bearings.