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1

Crystal Structure of NFAT Bound to the HIV-1 LTR Tandem ?B Enhancer Element  

SciTech Connect

Here, we have determined the crystal structure of the DNA binding domain of NFAT bound to the HIV-1 long terminal repeat (LTR) tandem {kappa}B enhancer element of 3.05 {angstrom} resolution. NFAT binds as a dimer to the upstream {kappa}B site (Core II), but as a monomer to the 3' end of the downstream {kappa}B site (Core I). The DNA shows a significant bend near the 5' end of Core I, where a lysine residue from NFAT bound to the 3' end of Core II inserts into the minor groove and seems to cause DNA bases to flip out. Consistent with this structural feature, the 5' end of Core I become hypersensitive to dimethylsulfate in the in vivo footprinting upon transcriptional activation of the HIV-1 LTR. Our studies provide a basis for futher investigating the functional mechanism of NFAT in HIV-1 transcription and replication.

Bates, Darren L.; Barthel, Kristen K.B.; Wu, Yongqing; Kalhor, Reza; Stroud, James C.; Giffin, Michael J.; Chen, Lin (UCLA); (Colorado)

2008-05-27

2

Enhanced expression, detection and purification of recombinant proteins using RNA stem loop and tandem fusion tags  

Microsoft Academic Search

The creation of a double His-tag fusion that forms a RNA stem loop in the mRNA encoding the N-terminus of the target protein\\u000a is a novel approach for the enhancement of expression, purification, and detection of a recombinant protein. Compared to a\\u000a single His-tag fusion, a tandem His-tag fusion RNA stem loop, located downstream of the constitutive groE and Ch

Mohamed Seleem; Mohammed Ali; M. W. Abd Al-Azeem; Stephen M. Boyle; Nammalwar Sriranganathan

2007-01-01

3

Tandem shock wave cavitation enhancement for extracorporeal lithotripsy.  

PubMed

Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 micros is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 micros using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator. PMID:12476975

Loske, Achim M; Prieto, Fernando E; Fernandez, Francisco; van Cauwelaert, Javier

2002-11-21

4

Tandem shock wave cavitation enhancement for extracorporeal lithotripsy  

NASA Astrophysics Data System (ADS)

Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 µs is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 µs using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator.

Loske, Achim M.; Prieto, Fernando E.; Fernández, Francisco; van Cauwelaert, Javier

2002-11-01

5

Tandem Fluorescent Proteins as Enhanced FRET-based Substrates for Botulinum Neurotoxin Activity  

PubMed Central

The light chain of botulinum neurotoxin A (BoNT/A-LC) is a zinc-metalloprotease that requires two extended exosites for optimal substrate binding and recognition of its intracellular target SNAP25. CFP and YFP connected through SNAP25 peptide (141–206) containing both exosites (CsY) has been used in a FRET-based assay for BoNT/A. To further improve the FRET efficiency in this BoNT/A substrate for in vitro high-throughput assays, we explored the feasibility of enhancing the capture of CFP emission by doubling the number of YFP acceptors. In comparison to CsY, the tandem fluorescence substrates CsYY and YsCsY enhanced the ratiometric fluorescence signal between YFP and CFP. YsCsY, containing two substrate sites, offered the greatest fluorometric change upon toxin-catalyzed cleavage. In addition to known approaches for enhancing fluorescence yield through various mutations, this alternative tandem substrate approach can boost the FRET signal and is particularly useful for substrates requiring extensive exosite recognition for specificity.

Pires-Alves, Melissa; Ho, Mengfei; Aberle, Karla K.; Janda, Kim D.; Wilson, Brenda A.

2009-01-01

6

Two structurally distinct {kappa}B sequence motifs cooperatively control LPS-induced KC gene transcription in mouse macrophages  

SciTech Connect

The mouse KC gene is an {alpha}-chemokine gene whose transcription is induced in mononuclear phagocytes by LPS. DNA sequences necessary for transcriptional control of KC by LPS were identified in the region flanking the transcription start site. Transient transfection analysis in macrophages using deletion mutants of a 1.5-kb sequence placed in front of the chloramphenicol acetyl transferase (CAT) gene identified an LPS-responsive region between residues -104 and +30. This region contained two {kappa}B sequence motifs. The first motif (position -70 to -59, {kappa}B1) is highly conserved in all three human GRO genes and in the mouse macrophage inflammatory protein-2 (MIP-2) gene. The second {kappa}B motif (position -89 to -78, {kappa}B2) was conserved only between the mouse and the rat KC genes. Consistent with previous reports, the highly conserved {kappa}B site ({kappa}B1) was essential for LPS inducibility. Surprisingly, the distal {kappa}B site ({kappa}B2) was also necessary for optimal response; mutation of either {kappa}B site markedly reduced sensitivity to LPS in RAW264.7 cells and to TNF-{alpha} in NIH 3T3 fibroblasts. Although both {kappa}B1 and {kappa}B2 sequences were able to bind members of the Rel homology family, including NF{kappa}B1 (P50), RelA (65), and c-Rel, the {kappa}B1 site bound these factors with higher affinity and functioned more effectively than the {kappa}B2 site in a heterologous promoter. These findings demonstrate that transcriptional control of the KC gene requires cooperation between two {kappa}B sites and is thus distinct from that of the three human GRO genes and the mouse MIP-2 gene. 71 refs., 8 figs.

Ohmori, Y.; Fukumoto, S.; Hamilton, T.A. [Cleveland Clinic Foundation, Cleveland, OH (United States)

1995-10-01

7

MEASUREMENT OF PYRETHROID RESIDUES IN ENVIRONMENTAL AND FOOD SAMPLES BY ENHANCED SOLVENT EXTRACTION/SUPERCRITICAL FLUID EXTRACTION COUPLED WITH GAS CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY  

EPA Science Inventory

The abstract summarizes pyrethorid methods development research. It provides a summary of sample preparation and analytical techniques such as supercritical fluid extraction, enhance solvent extraction, gas chromatography and tandem mass spectrometry....

8

Modulation of quaternary structure and enhancement of ligand binding by the K-turn of tandem glycine riboswitches.  

PubMed

Most known glycine riboswitches have two homologous aptamer domains arranged in tandem and separated by a short linker. The two aptamers associate through reciprocal "quaternary" interactions that have been proposed to result in cooperative glycine binding. Recently, the interaptamer linker was found to form helix P0 with a previously unrecognized segment 5' to the first aptamer domain. P0 was shown to increase glycine affinity, abolish cooperativity, and conform to the K-turn motif consensus. We examine the global thermodynamic and structural role of P0 using isothermal titration calorimetry (ITC) and small-angle X-ray scattering (SAXS), respectively. To evaluate the generality of P0 function, we prepared glycine riboswitch constructs lacking and including P0 from Bacillus subtilis, Fusobacterium nucleatum, and Vibrio cholerae. We find that P0 indeed folds into a K-turn, supports partial pre-folding of all three glycine-free RNAs, and is required for ITC observation of glycine binding under physiologic Mg(2+) concentrations. Except for the unusually small riboswitch from F. nucleatum, the K-turn is needed for maximally compacting the glycine-bound states of the RNAs. Formation of a ribonucleoprotein complex between the B. subtilis or the F. nucleatum RNA constructs and the bacterial K-turn binding protein YbxF promotes additional folding of the free riboswitch, and enhances glycine binding. Consistent with the previously reported loss of cooperativity, P0-containing B. subtilis and V. cholerae tandem aptamers bound no more than one glycine molecule per riboswitch. Our results indicate that the P0 K-turn helps organize the quaternary structure of tandem glycine riboswitches, thereby facilitating ligand binding under physiologic conditions. PMID:23249744

Baird, Nathan J; Ferré-D'Amaré, Adrian R

2012-12-17

9

Tandem metal-oxide affinity chromatography for enhanced depth of phosphoproteome analysis.  

PubMed

In eukaryotic cells many diverse cellular functions are regulated by reversible protein phosphorylation. In recent years, phosphoproteomics has become a powerful tool to study protein phosphorylation because it allows unbiased localization, and site-specific quantification, of in vivo phosphorylation of hundreds of proteins in a single experiment. A common strategy to identify phosphoproteins and their phosphorylation sites from complex biological samples is the enrichment of phosphopeptides from digested cellular lysates followed by mass spectrometry. However, despite the high sensitivity of modern mass spectrometers the large dynamic range of protein abundance and the transient nature of protein phosphorylation remained major pitfalls in MS-based phosphoproteomics. Tandem metal-oxide affinity chromatography (MOAC) represents a robust and highly selective approach for the identification and site-specific quantification of low abundant phosphoproteins that is based on the successive enrichment of phosphoproteins and -peptides. This strategy combines protein extraction under denaturing conditions, phosphoprotein enrichment using Al(OH)3-based MOAC, tryptic digestion of enriched phosphoproteins followed by TiO2-based MOAC of phosphopeptides. Thus, tandem MOAC effectively targets the phosphate moiety of phosphoproteins and phosphopeptides and, thus, allows probing of the phosphoproteome to unprecedented depth. PMID:24136551

Beckers, Gerold J M; Hoehenwarter, Wolfgang; Röhrig, Horst; Conrath, Uwe; Weckwerth, Wolfram

2014-01-01

10

Enhanced Detection of Sphingoid Bases via Divalent Ruthenium Bipyridine Complex Derivatization and Electrospray Ionization Tandem Mass Spectrometry  

PubMed Central

Sphingoid bases, such as unsaturated sphingosine (So) and its corresponding dihydro-saturated species sphinganine (Sa), are present in cell samples in low abundance. This fact combined with their low-to-moderate electrospray ionization (ESI) potential, compared to other sphingolipids such as sphingomyelins, limits their detection and quantitation by liquid chromatography tandem mass spectrometry (LC-MS2). To enhance the ESI efficiency of sphingoid bases, a novel procedure to generate stably derivatized analytes that enhance the LC-MS2 detection of sphingoid bases when analyzed using LC-MS2 was developed. In this method, a ruthenium complex, [4-(N-succimidyloxycarbonyl propyl)-4/-methy-2,2/-bipyridine] bis (2,2/-bipyridine) Ru(11) dihexafluorophosphate, is added directly to a cell extract. This complex reacts with and covalently binds to an amino group within the sphingoid bases. The dicationic nature of the ruthenium ion, enhances the compound’s ionization efficiency resulting in increased LC-MS2 signals for the derivatized sphingoid bases. Consequently, the detection and quantitation of sphingoid bases is greatly improved.

Masood, M. Athar; Xu, Xia; Acharya, Jairaj K.; Veenstra, Timothy D.; Blonder, Josip

2009-01-01

11

Broadband, polarization-insensitive and wide-angle absorption enhancement of a-Si:H/?c-Si:H tandem solar cells by nanopatterning a-Si:H layer.  

PubMed

A photonic crystal design that significantly enhances the absorption of tandem thin-film solar cells composed by amorphous and microcrystalline silicon (i.e., a-Si:H/?c-Si:H tandem cell) is proposed. The top junction with a-Si:H is nanopatterned as a one-dimensional photonic crystal. Considering the photocurrent matching, we optimally design the junction thickness and the configuration of the nanopattern; moreover, both transverse electric and magnetic incidences with various illuminating angles are taken into account. Calculations by rigorous coupled-wave approach and finite-element method show that the nanophotonic crystal design can improve the absorption and output photocurrent by over 20%, which shows very low sensitivity to the incident polarization. Moreover, the proposed structure is able to sustain the performance for a very wide angle ranges from 0° to ~80°. PMID:24104494

Li, Xiaofeng; Zhang, Cheng; Yang, Zhenhai; Shang, Aixue

2013-07-01

12

Enhanced detection of low abundance human plasma proteins using a tandem IgY12-SuperMix immunoaffinity separation strategy.  

PubMed

The enormous dynamic range of human bodily fluid proteomes poses a significant challenge for current MS-based proteomics technologies as it makes it especially difficult to detect low abundance proteins in human biofluids such as blood plasma, which is an essential aspect for successful biomarker discovery efforts. Here we present a novel tandem IgY12-SuperMix immunoaffinity separation system for enhanced detection of low abundance proteins in human plasma. The tandem IgY12-SuperMix system separates approximately 60 abundant proteins from the low abundance proteins in plasma, allowing for significant enrichment of low abundance plasma proteins in the SuperMix flow-through fraction. High reproducibility of the tandem separations was observed in terms of both sample processing recovery and LC-MS/MS identification results based on spectral count data. The ability to quantitatively measure differential protein abundances following application of the tandem separations was demonstrated by spiking six non-human standard proteins at three different levels into plasma. A side-by-side comparison between the SuperMix flow-through and IgY12 flow-through samples analyzed by both one- and two-dimensional LC-MS/MS revealed a 60-80% increase in proteome coverage as a result of the SuperMix separations, suggesting significantly enhanced detection of low abundance proteins. A total of 695 plasma proteins were confidently identified in a single analysis (with a minimum of two peptides per protein) by coupling the tandem separation strategy with two-dimensional LC-MS/MS, including 42 proteins with reported normal concentrations of approximately 100 pg/ml to 100 ng/ml. The concentrations of two selected proteins, macrophage colony-stimulating factor 1 and matrix metalloproteinase-8, were independently validated by ELISA as 202 pg/ml and 12.4 ng/ml, respectively. Evaluation of binding efficiency revealed that 45 medium abundance proteins were efficiently captured by the SuperMix column with >90% retention. Taken together, these results illustrate the potential broad utilities of this tandem IgY12-SuperMix strategy for proteomics applications involving human biofluids where effectively addressing the dynamic range challenge of the specimen is imperative. PMID:18632595

Qian, Wei-Jun; Kaleta, David T; Petritis, Brianne O; Jiang, Hongliang; Liu, Tao; Zhang, Xu; Mottaz, Heather M; Varnum, Susan M; Camp, David G; Huang, Lei; Fang, Xiangming; Zhang, Wei-Wei; Smith, Richard D

2008-07-15

13

Enhanced Detection of Low Abundance Human Plasma Proteins Using a Tandem IgY12-SuperMix Immunoaffinity Separation Strategy*S?  

PubMed Central

The enormous dynamic range of human bodily fluid proteomes poses a significant challenge for current MS-based proteomics technologies as it makes it especially difficult to detect low abundance proteins in human biofluids such as blood plasma, which is an essential aspect for successful biomarker discovery efforts. Here we present a novel tandem IgY12-SuperMix immunoaffinity separation system for enhanced detection of low abundance proteins in human plasma. The tandem IgY12-SuperMix system separates ?60 abundant proteins from the low abundance proteins in plasma, allowing for significant enrichment of low abundance plasma proteins in the SuperMix flow-through fraction. High reproducibility of the tandem separations was observed in terms of both sample processing recovery and LC-MS/MS identification results based on spectral count data. The ability to quantitatively measure differential protein abundances following application of the tandem separations was demonstrated by spiking six non-human standard proteins at three different levels into plasma. A side-by-side comparison between the SuperMix flow-through and IgY12 flow-through samples analyzed by both one- and two-dimensional LC-MS/MS revealed a 60–80% increase in proteome coverage as a result of the SuperMix separations, suggesting significantly enhanced detection of low abundance proteins. A total of 695 plasma proteins were confidently identified in a single analysis (with a minimum of two peptides per protein) by coupling the tandem separation strategy with two-dimensional LC-MS/MS, including 42 proteins with reported normal concentrations of ?100 pg/ml to 100 ng/ml. The concentrations of two selected proteins, macrophage colony-stimulating factor 1 and matrix metalloproteinase-8, were independently validated by ELISA as 202 pg/ml and 12.4 ng/ml, respectively. Evaluation of binding efficiency revealed that 45 medium abundance proteins were efficiently captured by the SuperMix column with >90% retention. Taken together, these results illustrate the potential broad utilities of this tandem IgY12-SuperMix strategy for proteomics applications involving human biofluids where effectively addressing the dynamic range challenge of the specimen is imperative.

Qian, Wei-Jun; Kaleta, David T.; Petritis, Brianne O.; Jiang, Hongliang; Liu, Tao; Zhang, Xu; Mottaz, Heather M.; Varnum, Susan M.; Camp, David G.; Huang, Lei; Fang, Xiangming; Zhang, Wei-Wei; Smith, Richard D.

2008-01-01

14

Tandem Repeat of a Transcriptional Enhancer Upstream of the Sterol 14alpha Demethylase Gene (CYP51) in Penicillium digitatum  

Microsoft Academic Search

We investigated the mechanism of resistance to demethylation inhibitors (DMI) in Penicillium digitatum by isolating the CYP51 gene, which encodes the target enzyme (P45014DM) of DMI, from three DMI-resistant and three DMI-sensitive strains. The structural genes of all six strains were identical, but in the promoter region, a unique 126-bp sequence was tandemly repeated five times in the DMI-resistant strains

HIROSHI HAMAMOTO; KOJI HASEGAWA; RYOJI NAKAUNE; YOUNG JIN LEE; YOSHIYUKI MAKIZUMI; KATSUMI AKUTSU; TADAAKI HIBI

2000-01-01

15

Tandemization of a Subregion of the Enhancer Sequences from SRS 19-6 Murine Leukemia Virus Associated with T-Lymphoid but Not Other Leukemias  

PubMed Central

Most simple retroviruses induce tumors of a single cell type when infected into susceptible hosts. The SRS 19-6 murine leukemia virus (MuLV), which originated in mainland China, induces leukemias of multiple cellular origins. Indeed, infected mice often harbor more than one tumor type. Since the enhancers of many MuLVs are major determinants of tumor specificity, we tested the role of the SRS 19-6 MuLV enhancers in its broad disease specificity. The enhancer elements of the Moloney MuLV (M-MuLV) were replaced by the 170-bp enhancers of SRS 19-6 MuLV, yielding the recombinants ?Mo+SRS+ and ?Mo+SRS? M-MuLV. M-MuLV normally induces T-lymphoid tumors in all infected mice. Surprisingly, when neonatal mice were inoculated with ?Mo+SRS+ or ?Mo+SRS? M-MuLV, all tumors were of T-lymphoid origin, typical of M-MuLV rather than SRS 19-6 MuLV. Thus, the SRS 19-6 MuLV enhancers did not confer the broad disease specificity of SRS 19-6 MuLV to M-MuLV. However, all tumors contained ?Mo+SRS M-MuLV proviruses with common enhancer alterations. These alterations consisted of tandem multimerization of a subregion of the SRS 19-6 enhancers, encompassing the conserved LVb and core sites and adjacent sequences. Moreover, when tumors induced by the parental SRS 19-6 MuLV were analyzed, most of the T-lymphoid tumors had similar enhancer alterations in the same region whereas tumors of other lineages retained the parental SRS 19-6 MuLV enhancers. These results emphasize the importance of a subregion of the SRS 19-6 MuLV enhancer in induction of T-cell lymphoma. The relevant sequences were consistent with crucial sequences for T-cell lymphomagenesis identified for other MuLVs such as M-MuLV and SL3-3 MuLV. These results also suggest that other regions of the SRS 19-6 MuLV genome contribute to its broad leukemogenic spectrum.

Granger, Steven W.; Bundy, Linda M.; Fan, Hung

1999-01-01

16

Effect of resveratrol on activation of nuclear factor kappa-B and inflammatory factors in rat model of acute pancreatitis  

Microsoft Academic Search

AIM: To observe the effect of resveratrol on nuclear factor Kappa-B (NF-?B) activation and the inflammatory response in sodium taurocholate-induced pancreatitis in rats. METHODS: Seventy-two male SD rats were randomly divided into three groups: sham operation group (control), severe acute pancreatitis (SAP) group, and severe acute pancreatitis group treated with resveratrol (RES). A SAP model was established by injecting 4%

Yong Meng; Qing-Yong Ma; Xiao-Ping Kou; Jun Xu

17

Tranilast inhibits cytokine-induced nuclear factor kappaB activation in vascular endothelial cells.  

PubMed

Tranilast [N-(3,4-dimethoxycinnamoyl)anthranilic acid] inhibits vascular inflammation. However, the relevant anti-inflammatory mechanisms are not completely understood. We studied the effects of tranilast on nuclear factor-kappaB (NF-kappaB)-dependent endothelial cell adhesion molecule expression and transcriptional regulation. Cultured human umbilical vein endothelial cells were preincubated with 12.5 to 100 microg/ml tranilast. Tumor necrosis factor-alpha (TNF-alpha)-induced endothelial VCAM-1, ICAM-1, and E-selectin surface expression was inhibited dose dependently. Maximal inhibition achieved with 100 microg/ml tranilast was 38 +/- 6.9, 31.8 +/- 1.5, and 31.9 +/- 1.9%, respectively (mean +/- S.E.M., p < 0.001, n = 5). Secretion of interleukin 6, which is also NF-kappaB-sensitive, was significantly inhibited by tranilast. Endothelial MHC-I expression, which is independent of NF-kappaB, was not inhibited. Although cytokine-induced degradation of NF-kappaB inhibitor proteins (IkappaB-alpha, -beta, and -epsilon), nuclear translocation of NF-kappaB, and binding of NF-kappaB to kappaB cis-acting elements in the adhesion molecule promoters were not affected by tranilast, ICAM-1-kappaB and E-selectin-kappaB reporter gene activity was inhibited by 53% (n = 5, p < 0.01) and 51% (n = 5, p < 0.001), respectively. In contrast, using SP-1 and C/EBP constructs, reporter gene activity was not altered. Expression of the transcriptional coactivator cAMP response element binding protein binding protein (CBP) was inhibited by tranilast, resulting in a loss of interaction between NF-kappaB and CBP. Therefore, in therapeutically relevant concentrations (50 microg/ml), tranilast inhibits NF-kappaB-dependent transcriptional activation by interfering with the NF-kappaB/CBP association. We propose that inhibition of NF-kappaB dependent gene transcription contributes to the anti-inflammatory effects of tranilast. PMID:12237332

Spiecker, Martin; Lorenz, Ioana; Marx, Nikolaus; Darius, Harald

2002-10-01

18

Cardiovascular disease associated with radiotherapy: activation of nuclear factor kappa-B.  

PubMed

There have been several recent reports of an increased risk of cardiovascular disease after radiotherapy. Hence, with an increasing number of cancer survivors, the incidence of cardiovascular disease caused by radiotherapy will increase. The existence of a type of vascular disease, or vasculopathy, induced by radiotherapy has been known for decades. It is important to identify and understand the molecular causes of this vasculopathy to determine preventive strategies. Recently, a chronic inflammation with similarities to atherosclerosis has been observed, with activation of the transcription factor nuclear factor kappa-B (NF-?B) as a possible cause. However, the trigger for NF-?B activation is unclear although it may be that reactive oxygen species or direct DNA damage is involved. To minimize the risk of cardiovascular disease in vulnerable patients, careful selection of patients, radiation dose and fractionation are important, together with the development of new techniques that reduce radiation dose to the blood vessels. In the light of the finding of an interaction between risk factors for cardiovascular disease and radiotherapy, it is reasonable to modify these factors including diabetes mellitus, hyperlipidaemia, hypertension and smoking. We believe that preventive strategies focusing on NF-?B can reduce the risk of future adverse cardiovascular events. PMID:21255133

Halle, M; Hall, P; Tornvall, P

2011-02-22

19

Manganese potentiates lipopolysaccharide-induced expression of NOS2 in C6 glioma cells through mitochondrial-dependent activation of nuclear factor kappaB.  

PubMed

Neuronal injury in manganese neurotoxicity (manganism) is thought to involve activation of astroglial cells and subsequent overproduction of nitric oxide (NO) by inducible nitric oxide synthase (NOS2). Manganese (Mn) enhances the effects of proinflammatory cytokines on expression of NOS2 but the molecular basis for this effect has not been established. It was postulated in the present studies that Mn enhances expression of NOS2 through the cis-acting factor, nuclear factor kappaB (NF-kappaB). Exposure of C6 glioma cells to lipopopolysaccharide (LPS) resulted in increased expression of NOS2 and production of NO that was dramatically potentiated by Mn and was blocked through overexpression of mutant IkappaBalpha (S32/36A). LPS-induced DNA binding of p65/p50 was similarly enhanced by Mn and was decreased by mutant IkappaBalpha. Phosphorylation of IkappaBalpha was potentiated by Mn and LPS and was not blocked by U0126, a selective inhibitor of ERK1/2. Mn decreased mitochondrial membrane potential and increased matrix calcium, associated with a rise in intracellular reactive oxygen species (ROS) that was attenuated by the mitochondrial-specific antioxidant, MitoQ. Blocking mitochondrial ROS also attenuated the enhancing effect of Mn on LPS-induced phosphorylation of IkappaBalpha and expression of NOS2, suggesting a link between Mn-induced mitochondrial dysfunction and activation of NF-kappaB. Overexpression of a dominant-negative mutant of the NF-kappaB-interacting kinase (Nik) prevented enhancement of LPS-induced phosphorylation of IkappaBalpha by Mn. These data indicate that Mn augments LPS-induced expression of NOS2 in C6 cells by increasing mitochondrial ROS and activation of NF-kappaB. PMID:15010209

Barhoumi, Rola; Faske, Jennifer; Liu, Xuhong; Tjalkens, Ronald B

2004-03-30

20

A tandem sequence motif acts as a distance-dependent enhancer in a set of genes involved in translation by binding the proteins NonO and SFPQ  

PubMed Central

Background Bioinformatic analyses of expression control sequences in promoters of co-expressed or functionally related genes enable the discovery of common regulatory sequence motifs that might be involved in co-ordinated gene expression. By studying promoter sequences of the human ribosomal protein genes we recently identified a novel highly specific Localized Tandem Sequence Motif (LTSM). In this work we sought to identify additional genes and LTSM-binding proteins to elucidate potential regulatory mechanisms. Results Genome-wide analyses allowed finding a considerable number of additional LTSM-positive genes, the products of which are involved in translation, among them, translation initiation and elongation factors, and 5S rRNA. Electromobility shift assays then showed specific signals demonstrating the binding of protein complexes to LTSM in ribosomal protein gene promoters. Pull-down assays with LTSM-containing oligonucleotides and subsequent mass spectrometric analysis identified the related multifunctional nucleotide binding proteins NonO and SFPQ in the binding complex. Functional characterization then revealed that LTSM enhances the transcriptional activity of the promoters in dependency of the distance from the transcription start site. Conclusions Our data demonstrate the power of bioinformatic analyses for the identification of biologically relevant sequence motifs. LTSM and the here found LTSM-binding proteins NonO and SFPQ were discovered through a synergistic combination of bioinformatic and biochemical methods and are regulators of the expression of a set of genes of the translational apparatus in a distance-dependent manner.

2011-01-01

21

Analysis of estrogenic compounds in environmental and biological samples by liquid chromatography-tandem mass spectrometry with stable isotope-coded ionization-enhancing reagent.  

PubMed

A sensitive and reliable stable isotope labeling technology was developed for the determination of estrogenic compounds in environmental and biological samples based on the derivatization of estrogenic compounds with 10-methyl-acridone-2-sulfonyl chloride (d(0)-MASC) and its deuterated counterpart d(3)-MASC. The labeling reaction of MASC with estrogenic compounds is simple and robust and can be carried out under mild conditions within 5 min. Internal standard-based quantification was achieved by this labeling strategy without the need of using expensive internal standard analogy to every analyte of interest. Meanwhile, the sensitivity obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was enhanced by 2-3 orders of magnitude compared to the underivatized counterparts. Application of the stable isotope labeling technology in relative and absolute quantification of estrogenic compounds in complicated samples indicated that the labeling strategy was effective in overcoming matrix effects. The proposed method was successfully applied to the analysis estrogenic compounds in different environmental and biological samples with high sensitivity and accuracy. PMID:23374368

Zhang, Shijuan; You, Jinmao; Ning, Shujing; Song, Cuihua; Suo, You-Rui

2013-01-16

22

Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of carbamates in wines by ultra-high performance liquid chromatography-tandem mass spectrometry.  

PubMed

A new sensitive multiresidue method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the detection, confirmation and quantification of twenty five carbamates in wine samples. The separation was achieved in 5.5min, using a Zorbax Eclipse plus RRHD C18 column (50mm×2.1mm, 1.8?m), with a mobile phase of water and methanol, both of them with 0.01% formic acid. The analytes were detected in positive mode with multiple reaction monitoring mode. Ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME), using a low-density extraction solvent has been optimized for the satisfactory extraction of carbamates and clean-up of extracts. The matrix effect was studied, showing that the proposed procedure provides very clean extracts. Under optimum conditions, recoveries for fortified wine samples ranged from 74 to 102%, with relative standard deviations lower than 6%. Limits of quantification ranged from 0.15 to 0.92?gl(-1), showing the high sensitivity of this fast and simple method and its compliance with current requirements. PMID:24094484

Moreno-González, David; Huertas-Pérez, José F; García-Campaña, Ana M; Bosque-Sendra, Juan M; Gámiz-Gracia, Laura

2013-09-13

23

Tandem betatron  

DOEpatents

Two betatrons are provided in tandem for alternately accelerating an electron beam to avoid the single flux swing limitation of conventional betatrons and to accelerate the electron beam to high energies. The electron beam is accelerated in a first betatron during a period of increasing magnetic flux. The electron beam is extracted from the first betatron as a peak magnetic flux is reached and then injected into a second betatron at a time of minimum magnetic flux in the second betatron. The cycle may be repeated until the desired electron beam energy is obtained. In one embodiment, the second betatron is axially offset from the first betatron to provide for electron beam injection directly at the axial location of the beam orbit in the second betatron.

Keinigs, R.K.

1991-01-01

24

Tandem betatron  

DOEpatents

Two betatrons are provided in tandem for alternately accelerating an electron beam to avoid the single flux swing limitation of conventional betatrons and to accelerate the electron beam to high energies. The electron beam is accelerated in a first betatron during a period of increasing magnetic flux. The electron beam is extracted from the first betatron as a peak magnetic flux is reached and then injected into a second betatron at a time of minimum magnetic flux in the second betatron. The cycle may be repeated until the desired electron beam energy is obtained. In one embodiment, the second betatron is axially offset from the first betatron to provide for electron beam injection directly at the axial location of the beam orbit in the second betatron.

Keinigs, R.K.

1991-12-31

25

Tandem assays of protein and glucose with functionalized core/shell particles based on magnetic separation and surface-enhanced Raman scattering.  

PubMed

Tandem assays of protein and glucose in combination with mannose-functionalized Fe3 O4 @SiO2 and Ag@SiO2 tag particles have promising potential in effective magnetic separation and highly sensitive and selective SERS assays of biomaterials. It is for the first time that tandem assay of glucose is developed using SERS based on the Con A-sandwiched microstructures between the functionalized magnetic and tag particles. PMID:23585333

Kong, Xianming; Yu, Qian; Lv, Zhongpeng; Du, Xuezhong

2013-04-15

26

Whole grape intake impacts cardiac peroxisome proliferator-activated receptor and nuclear factor kappaB activity and cytokine expression in rats with diastolic dysfunction.  

PubMed

Prolonged hypertension is the leading cause of heart failure. Failing hearts show reduced peroxisome proliferator-activating receptor (PPAR) activity and enhanced nuclear factor kappaB (NF-kappaB) activity, which together modify cardiac inflammation and fibrosis. In vitro studies suggest that phytochemicals alter PPAR and NF-kappaB activity, but the capabilities of a phytochemical-rich diet are less understood. Grapes contain an array of commonly consumed dietary phytochemicals. In Dahl salt-sensitive hypertensive rats, we showed previously that dietary provision of whole table grape powder (3% weight:weight) for 18 weeks reduced blood pressure, cardiac hypertrophy, and diastolic dysfunction. The hypothesis tested here is that, in this model, phytochemical provision from whole grape powder impacts cardiac PPAR and NF-kappaB activity and their related gene transcripts. Grape-fed rats had enhanced PPAR-alpha and PPAR-gamma DNA binding activity but reduced NF-kappaB DNA binding activity. RT-PCR revealed that grape-fed rats showed upregulated mRNA for PPAR-alpha, PPAR-gamma coactivator-1alpha, PPAR-gamma, and the cytosolic NF-kappaB inhibitor, inhibitor-kappaBalpha. By contrast, grape-fed rats showed downregulated mRNA for tumor necrosis factor-alpha and transforming growth factor-beta1. Finally, grape-fed rats showed significantly reduced cardiac tumor necrosis factor-alpha and transforming growth factor-beta protein expression, increased inhibitor-kappaBalpha expression, and reduced cardiac fibrosis. In the Dahl salt-sensitive rat, chronic intake of grapes altered cardiac transcripts related to PPAR and NF-kappaB that may be significant to the observed diet-associated cardioprotection. PMID:20231522

Seymour, E Mitchell; Bennink, Maurice R; Watts, Stephanie W; Bolling, Steven F

2010-03-15

27

Enhanced short wavelength response in laser-scanned-photodiode image sensor using an aSiC:H\\/aSi:H tandem structure  

Microsoft Academic Search

We report in this paper the recent advances we obtained in optimizing a color image sensor based on the laser-scanned-photodiode (LSP) technique. A novel device structure based on a a-SiC:H\\/a-Si:H pin\\/pin tandem structure has been tested for a proper color separation process that takes advantage on the different filtering properties due to the different light penetration depth at different wavelengths

A. Fantoni; P. Louro; M. Fernandes; M. Vieira; G. Lavareda; C. Nunes De Carvalho

2005-01-01

28

Effect of fluoride on calcium ion concentration and expression of nuclear transcription factor kappa-B ?65 in rat hippocampus.  

PubMed

The study investigated the neurotoxicity of drinking water fluorosis in rat hippocampus. Just weaning male Sprague-Dawley (SD) rats were given 15, 30, 60 mg/L NaF solution and tap water for 9 months. The calcium ion concentration ([Ca(2+)]) in synaptosomes was measured by double wavelength fluorescence spectrophotometer and the expression level of nuclear transcription factor kappa-B ?65 (NF-?B ?65) in hippocampal CA3 region was measured by immunohistochemistry. The results showed that [Ca(2+)] significantly increased (F = 33.218, P < 0.01) in moderate fluoride group compared with the control group, and the expression level of NF-?B ?65 in CA3 region presented an increasing trend as fluoride concentration increased. These results indicate that increase of synaptosomes [Ca(2+)] and NF-?B ?65 expression level may be the molecular basis of central nervous system damage caused by chronic fluoride intoxication. NF-?B ?65 in CA3 region is probably a target molecule for fluorosis. PMID:20304620

Zhang, Jing; Zhu, Wen-Jing; Xu, Xiao-Hong; Zhang, Zi-Gui

2010-03-21

29

Tandem hydrofoil system  

Microsoft Academic Search

A tandem hydrofoil system enables an improvement in the lift-drag ratio of a high-speed ship. The conditions for favorable application of this type of foil structure are determined. The data on hydrofoil boats using a tandem system are presented. The problem of the stability of the vertical plane motion of a hydrofoil with bow and stern foils is considered. The

Konstantin I. Matveev; Ivan Ivanovich Matveev

2001-01-01

30

The tandem ?-zipper: modular binding of tandem domains and linear motifs.  

PubMed

The tandem ?-zipper protein-protein binding interface involves an intrinsically disordered protein (IDP) binding two or more globular domains through ?-sheet-augmentation in a modular fashion, and represents a paradigm in IDP-mediated protein-protein interactions. While characterised tandem ?-zippers are rare, known examples are associated with diverse biological processes. A combination of their advantages (binding specificity and the ability to generate high affinity binding sites by linking multiple lower affinity motifs) and the prevalence of both tandem domains and IDPs points to the existence of many more ?-zippers in nature. The characterisation of these interactions has greatly enhanced the understanding of the biological systems involved but given their apparent tolerance to mutation, detecting other tandem ?-zipper interactions using bioinformatics may be challenging. PMID:23333654

Matthews, Jacqueline M; Potts, Jennifer R

2013-01-16

31

Nucling mediates apoptosis by inhibiting expression of galectin-3 through interference with nuclear factor kappaB signalling.  

PubMed Central

Nucling is a novel apoptosis-associated molecule, which is involved with cytochrome c /Apaf-1/caspase-9 apoptosome induction following pro-apoptotic stress. In the present study, we show first that Nucling is able to interact with galectin-3. Galectin-3 is known to participate in many biological processes, including apoptotic cell death. Nucling was found to down-regulate the expression level of galectin-3 mRNA/protein. Nucling-deficient cells, in which galectin-3 expression is up-regulated, appeared to be resistant to some forms of pro-apoptotic stress as compared with wild-type cells. In addition, the preputial gland from Nucling-deficient mice expressed a significant level of galectin-3 and exhibited a high incidence of inflammatory lesions, indicating that Nucling plays a crucial role in the homoeostasis of this gland by interacting with the galectin-3 molecule and regulating the expression level of galectin-3. Up-regulation of galectin-3 was also observed in the heart, kidney, lung, testis and ovary of the Nucling-deficient mice. In order to confirm the functional interaction between Nucling and galectin-3, a well-documented candidate for the mediator of galectin-3 expression, NF-kappaB (nuclear factor kappaB), was investigated as well. Nucling was shown to interfere with NF-kappaB activation via the nuclear translocation process of NF-kappaB/p65, thus inhibiting the expression of galectin-3. Taken together, we propose that Nucling mediates apoptosis by interacting and inhibiting expression of galectin-3.

Liu, Li; Sakai, Takashi; Sano, Nobuya; Fukui, Kiyoshi

2004-01-01

32

Direct angiotensin II type 2 receptor stimulation acts anti-inflammatory through epoxyeicosatrienoic acid and inhibition of nuclear factor kappaB.  

PubMed

Angiotensin II type 2 (AT(2)) receptors can be regarded as an endogenous repair system, because the AT(2) receptor is upregulated in tissue damage and mediates tissue protection. A potential therapeutic use of this system has only recently come within reach through synthesis of the first selective, orally active, nonpeptide AT(2) receptor agonist, compound 21 (C21; dissociation constant for AT(2) receptor: 0.4 nM; dissociation constant for angiotensin II type 1 receptor: >10,000 nM). This study tested AT(2) receptor stimulation with C21 as a potential future therapeutic approach for the inhibition of proinflammatory cytokines and of nuclear factor kappaB. C21 dose-dependently (1 nM to 1 micromol/L) reduced tumor necrosis factor-alpha-induced interleukin 6 levels in primary human and murine dermal fibroblasts. AT(2) receptor specificity was controlled for by inhibition with the AT(2) receptor antagonist PD123319 and by the absence of effects in AT(2) receptor-deficient cells. AT(2) receptor-coupled signaling leading to reduced interleukin 6 levels involved inhibition of nuclear factor kappaB, activation of protein phosphatases, and synthesis of epoxyeicosatrienoic acid. Inhibition of interleukin 6 promoter activity by C21 was comparable in strength to inhibition by hydrocortisone. C21 also reduced monocyte chemoattractant protein 1 and tumor necrosis factor-alpha in vitro and in bleomycin-induced toxic cutaneous inflammation in vivo. This study is the first to show the anti-inflammatory effects of direct AT(2) receptor stimulation in vitro and in vivo by the orally active, nonpeptide AT(2) receptor agonist C21. These data suggest that pharmacological AT(2) receptor stimulation may be an orally applicable future therapeutic approach in pathological settings requiring the reduction of interleukin 6 or inhibition of nuclear factor kappaB. PMID:20157051

Rompe, Franziska; Artuc, Metin; Hallberg, Anders; Alterman, Mathias; Ströder, Katja; Thöne-Reineke, Christa; Reichenbach, Anne; Schacherl, Jens; Dahlöf, Björn; Bader, Michael; Alenina, Natalia; Schwaninger, Markus; Zuberbier, Torsten; Funke-Kaiser, Heiko; Schmidt, Cosima; Schunck, Wolf-Hagen; Unger, Thomas; Steckelings, U Muscha

2010-02-15

33

Enhanced determination of abscisic acid (ABA) and abscisic acid glucose ester (ABA-GE) in Cistus albidus plants by liquid chromatography-mass spectrometry in tandem mode.  

PubMed

An improved, quick and simple method for the extraction and quantification of the phytohormones (+)-abscisic acid (ABA) and its major glucose conjugate, abscisic acid glucose ester (ABA-GE) in plant samples is described. The method includes the addition of deuterium-labeled internal standards to the leaves at the beginning of the extraction for quantification, a simple extraction/centrifugation process and the injection into the liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) system in multiple reaction monitoring mode (MRM). Quality parameters of the method (detection limits, repeatability, reproducibility and linearity) have been studied. The objective of this work is to show the applicability of this method for quantifying the endogenous content of both ABA and ABA-GE in Cistus albidus plants that have been grown during an annual cycle under Mediterranean field conditions. Leaf samples from winter plants have low levels of ABA which increase in spring and summer showing two peaks that corresponded to April and August. These increases are coincident with the high temperature and solar radiation and the low RWC and RH registered along the year. On the other hand, the endogenous levels of ABA-GE increase until maximum values in July just before the ABA content reaches its highest concentration, decreasing in August and during autumn and winter. Our results suggest that the method is useful for quantifying both compounds in this plant material and represents the advantage of a short-time sample preparation with a high accuracy and viability. PMID:19167901

López-Carbonell, Marta; Gabasa, Marta; Jáuregui, Olga

2008-12-30

34

Thyrotropin modifies activation of nuclear factor kappaB by tumour necrosis factor alpha in rat thyroid cell line.  

PubMed Central

We have recently demonstrated that nuclear factor kappaB (NF-kappaB) mediates the tumour necrosis factor alpha (TNF-alpha)-dependent expression of the gene encoding interleukin 6 (IL-6) in rat thyroid FRTL-5 cells cultured in the presence of thyrotropin (TSH). In the present study we investigated how TSH is involved in the activation of NF-kappaB by TNF-alpha in the cells. Electrophoretic mobility-shift assay revealed that, in the absence of TSH, TNF-alpha activated a single protein-DNA complex containing the p50 subunit but not other NF-kappaB subunits such as p65. In contrast, two distinct protein-DNA complexes were activated in the presence of TSH: the faster-migrating complex contained only p50 subunit; the slower-migrating complex consisted of p65-p50 heterodimer. This TSH effect was mimicked by forskolin and thyroid-stimulating antibodies obtained from patients with Graves's disease, suggesting that an increase in intracellular cAMP is responsible for the induction of different NF-kappaBs by TNF-alpha. A transient transfection study with a luciferase reporter gene driven by multimerized NF-kappaB sites demonstrated that TNF-alpha increased the luciferase activities only in the presence of TSH, and that this increase was inhibited by the co-transfection of mutant p65, which prevented the function of wild-type p65 in a dominant-negative manner. Accordingly, TNF-alpha activated the expression of the IL-6 gene in the presence of TSH but not in its absence. Although the expression of the p105 gene, another known target for NF-kappaB, was increased by TNF-alpha in the absence of TSH, the presence of TSH further increased the mRNA level. Taken together, these observations indicate that the presence of TSH is crucial for the NF-kappaB-mediated actions of TNF-alpha on thyroid follicular cells.

Kikumori, T; Kambe, F; Nagaya, T; Funahashi, H; Seo, H

2001-01-01

35

Tandem Brownian Queues.  

National Technical Information Service (NTIS)

We analyze a two-node tandem queue with Brownian input. We first derive an explicit expression for the joint distribution function of the workloads of the first and second queue, which also allows us to calculate their exact large-buffer asymptotics. The ...

M. R. H. Mandjes P. M. D. Lieshout

2006-01-01

36

Tandem mirror fusion research  

SciTech Connect

The tandem mirror program has evolved considerably in the last decade. Of significance is the viable reactor concept embodied in the MARS design. An aggressive experimental program, culminating in the operation of MFTF-B in late 1986, will provide a firm basis for refining the MARS design as necessary for constructing a reactor prototype in the 1990s.

Baldwin, D.E.

1983-12-02

37

Tandem resonator reflectance modulator  

Microsoft Academic Search

A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and

I. J. Fritz; J. R. Wendt

1994-01-01

38

Characterization of the Inhibitor of KappaB Kinase (IKK) Complex in Granulosa Cell Tumors of the Ovary and Granulosa Cell Tumor-Derived Cell Lines.  

PubMed

Granulosa cell tumors of the ovary (GCT) are a distinct, hormonally active subset of ovarian cancers. Although it has recently been shown that ?97 % of all adult GCT harbor a novel somatic missense mutation in the FOXL2 gene, given its almost universal presence, it does not explain differences in tumor stage and/or recurrence. The nuclear factor kappaB (NF?B) transcription factor is constitutively active in two human GCT-derived cell lines, COV434 and KGN, which are useful in vitro models to investigate juvenile and adult GCT, respectively. This study aimed to determine the molecular basis and pathogenetic significance of this aberrant NF?B activity. Selective chemical inhibitors were used to target candidate components of the pathway. The constitutive activity was blocked by two independent inhibitors of I?B? phosphorylation, suggesting that aberrant activation occurs upstream of this point. NF?B inhibition resulted in a dose-dependent decrease in cell proliferation and viability and a dose-dependent increase in apoptosis. Inhibitors of earlier components of the pathway were without effect. Two independent inhibitors of inhibitor of kappaB kinase (IKK)?, a catalytic subunit of the NF?B activation complex, were unable to inhibit the constitutive activity, but surprisingly also ligand-induced activity. These findings suggest a central role for IKK?; however, no mutations or altered expression of the IKK?, IKK?, or IKK? genes was observed in the cell lines or in a panel of human GCT samples. This study highlights unresolved issues in understanding the pathogenesis of GCT and in the use of the COV434 and KGN cells lines as model systems. PMID:23674259

Jamieson, Stacey; Fuller, Peter J

2013-05-15

39

Tandem resonator reflectance modulator  

SciTech Connect

A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

Fritz, I.J.; Wendt, J.R.

1994-09-06

40

Current results of the tandem mirror experiment  

SciTech Connect

The basic operating characteristics of the Tandem Mirror Experiment, (TMX) at the Lawrence Livermore Laboratory in the USA have been established. Tandem-mirror plasmas have been produced using neutral-beam-fueled end plugs and a gas-fueled center cell. An axial potential well between the end plugs has been measured. There is direct evidence that this potential well enhances the axial confinement of the center-cell ions. The observed densities and loss currents are consistent with preliminary studies of the particle sources and losses near the magnetic axis. The observed confinement is consistent with theory when plasma fluctuations are low. When the requirement of drift-cyclotron loss-cone mode stability is violated, the plasma fluctuations degrade the center-cell confinement.

Drake, R.P.

1980-04-09

41

Tandems as injectors for synchrotrons  

SciTech Connect

This is a review on the use of Tandem electrostatic accelerators for injection and filling of synchrotrons to accelerate intense beams of heavy-ions to relativistic energies. The paper emphasizes the need of operating the Tandems in pulsed mode for this application. It has been experimentally demonstrated that at the present this type of accelerators still provides the most reliable and best performance.

Ruggiero, A.G.

1992-08-01

42

Tandems as injectors for synchrotrons  

SciTech Connect

This is a review on the use of Tandem electrostatic accelerators for injection and filling of synchrotrons to accelerate intense beams of heavy-ions to relativistic energies. The paper emphasizes the need of operating the Tandems in pulsed mode for this application. It has been experimentally demonstrated that at the present this type of accelerators still provides the most reliable and best performance.

Ruggiero, A.G.

1992-01-01

43

Spinal nerve ligation–induced activation of nuclear factor kappaB is facilitated by prostaglandins in the affected spinal cord and is a critical step in the development of mechanical allodynia  

Microsoft Academic Search

This study investigated the effect of 5th and 6th lumbar nerve (L5\\/L6) spinal nerve ligation (SNL) on activated nuclear factor kappaB (NFkBa) in nuclear extracts from the lumbar dorsal horn of the rat, and its relationship to prostaglandin (PG)-dependent spinal hyperexcitability and allodynia 3 days later. Male Sprague–Dawley rats, fitted with intrathecal (i.t.) catheters, underwent SNL- or sham-surgery. Paw withdrawal

D. D. O'Rielly; C. W. Loomis

2008-01-01

44

Alpha-melanocyte-related tripeptide, Lys-d-Pro-Val, ameliorates endotoxin-induced nuclear factor kappaB translocation and activation: evidence for involvement of an interleukin-1beta193-195 receptor antagonism in the alveolar epithelium.  

PubMed Central

The potential anti-inflammatory role of alpha-melanocyte-stimulating hormone (alpha-MSH)-related tripeptide, lysine(11)-D-proline-valine(13) (KDPV), an analogue of interleukin (IL)-1beta(193-195) and an antagonist of IL-1beta/prostaglandin E(2), is not well characterized in the alveolar epithelium. In a model of foetal alveolar type II epithelial cells in vitro, we showed that lipopolysaccharide endotoxin (LPS) differentially, but selectively, induced the nuclear subunit composition of nuclear factor kappaB(1) (NF-kappaB(1)) (p50), RelA (p65) and c-Rel (p75), in parallel to up-regulating the DNA-binding activity (supershift indicating the presence of the p50-p65 complex). LPS accelerated the degradation of inhibitory kappaB-alpha (IkappaB-alpha), accompanied by enhancing its phosphorylation in the cytosolic compartment but not in the nucleus. KDPV suppressed, in a dose-dependent manner, the nuclear localization of p50, p65 and p75, an effect that led to the subsequent inhibition of NF-kappaB activation. Interleukin-1 receptor antagonist (IL-1ra) decreased the nuclear abundance of p50, p65 and p75, and subsequently depressed the DNA-binding activity induced by LPS. Analysis of the mechanism involved in the KDPV- and IL-1ra-mediated inhibition of NF-kappaB nuclear localization revealed a reversal in IkappaB-alpha phosphorylation and degradation, followed by cytosolic accumulation. LPS induced endogenous IL-1beta biosynthesis in a time-dependent manner; the administration of exogenous recombinant human interleukin 1 (rhIL-1) resulted in a dose-dependent activation of NF-kappaB. KDPV and IL-1ra abrogated the effect of rhIL-1. Pretreatment with the non-steroidal anti-inflammatory drug (NSAID) indomethacin, an inhibitor of cyclo-oxygenase, blocked the LPS-induced activation of NF-kappaB. These results indicate the involvement of prostanoid-dependent (NSAID-sensitive) and IL-1-dependent (IL-1ra-sensitive) mechanisms mediating LPS-induced NF-kappaB translocation and activation, a pathway that is regulated, in part, by a negative feedback mechanism transduced through IkappaB-alpha, the major cytosolic inhibitor of NF-kappaB.

Haddad, J J; Lauterbach, R; Saade, N E; Safieh-Garabedian, B; Land, S C

2001-01-01

45

TANDEM SHOCK WAVES FOR EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY  

Microsoft Academic Search

Extracorporeal shock wave lithotripsy (SWL) has become the standard treatment for patients with renal calculi; however, shock waves are not innocuous when focused on the kidney. This paper reports the design of a novel piezoelectric tandem shock wave generator for SWL. The system generates two shock waves with an adjustable time delay (50 - 950 ?sec) to enhance cavitation-induced damage

Francisco Fernández; Fernando E. Prieto; Tecnología Avanzada

46

Nuclear factor {kappa}B (NF{kappa}B) and cyclooxygenase-2 (Cox-2) expression in the irradiated colorectum is associated with subsequent histopathological changes  

SciTech Connect

Purpose: Recent studies have proposed that mucositis development is the same throughout the gastrointestinal tract (GIT), as it is formed from one structure embryologically. Radiation-induced oral mucositis studies have outlined the key involvement of nuclear factor {kappa}B (NF{kappa}B) and cyclooxygenase-2 (Cox-2) in its pathobiology. The purpose of this study was therefore to investigate the expression of NF{kappa}B and Cox-2 in the irradiated colorectum and to correlate these with the associated histopathologic changes. Methods and Materials: Colorectal tissues from 28 colorectal cancer patients treated with preoperative radiotherapy were analyzed for histopathologic changes using a variety of tissue staining methods. The expression of NF{kappa}B and Cox-2 in these tissues was investigated using immunohistochemistry. Changes in expression of these proteins were then correlated with the histopathologic changes. Results: Radiation therapy caused injury to the normal colorectal tissue surrounding tumor site, particularly around the blood vessels. These changes were reflected in changes in NF{kappa}B and Cox-2 expression. Conclusions: We conclude that different regions of the GIT, the colorectum, and oral cavity have similar underlying mechanisms of radiation-induced mucositis. Understanding these mechanisms will allow new approaches to be developed to specifically target steps in the evolution of alimentary mucositis.

Yeoh, Ann S.J. [Department of Medical Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia) and Department of Physiology, School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, South Australia (Australia)]. E-mail: ann.yeoh@imvs.sa.gov.au; Bowen, Joanne M. [Department of Medical Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia); Department of Medicine, University of Adelaide, Adelaide, South Australia (Australia); Gibson, Rachel J. [Department of Medical Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia); Department of Medicine, University of Adelaide, Adelaide, South Australia (Australia); Keefe, Dorothy M.K. [Department of Medical Oncology, Royal Adelaide Hospital, Adelaide, South Australia (Australia); Department of Medicine, University of Adelaide, Adelaide, South Australia (Australia)

2005-12-01

47

1'-acetoxychavicol acetate is a novel nuclear factor kappaB inhibitor with significant activity against multiple myeloma in vitro and in vivo.  

PubMed

1'-Acetoxychavicol acetate (ACA) is a component of a traditional Asian condiment obtained from the rhizomes of the commonly used ethno-medicinal plant Languas galanga. Here, we show for the first time that ACA dramatically inhibits the cellular growth of human myeloma cells via the inhibition of nuclear factor kappaB (NF-kappaB) activity. In myeloma cells, cultivation with ACA induced G0-G1 phase cell cycle arrest, followed by apoptosis. Treatment with ACA induced caspase 3, 9, and 8 activities, suggesting that ACA-induced apoptosis in myeloma cells mediates both mitochondrial- and Fas-dependent pathways. Furthermore, we showed that ACA significantly inhibits the serine phosphorylation and degradation of IkappaBalpha. ACA rapidly decreased the nuclear expression of NF-kappaB, but increased the accumulation of cytosol NF-kappaB in RPMI8226 cells, indicating that ACA inhibits the translocation of NF-kappaB from the cytosol to the nucleus. To evaluate the effects of ACA in vivo, RPMI8226-transplanted NOD/SCID mice were treated with ACA. Tumor weight significantly decreased in the ACA-treated mice compared with the control mice. In conclusion, ACA has an inhibitory effect on NF-kappaB, and induces the apoptosis of myeloma cells in vitro and in vivo. ACA, therefore, provides a new biologically based therapy for the treatment of multiple myeloma patients as a novel NF-kappaB inhibitor. PMID:15899834

Ito, Keisuke; Nakazato, Tomonori; Xian, Ming Ji; Yamada, Taketo; Hozumi, Nobumichi; Murakami, Akira; Ohigashi, Hajime; Ikeda, Yasuo; Kizaki, Masahiro

2005-05-15

48

Covalently linked tandem lesions in DNA.  

PubMed

Reactive oxygen species (ROS) generate a type of DNA damage called tandem lesions, two adjacent nucleotides both modified. A subcategory of tandem lesions consists of adjacent nucleotides linked by a covalent bond. Covalently linked tandem lesions generate highly characteristic liquid chromotography-tandem mass spectrometry (LC-MS/MS) elution profiles. We have used this property to comprehensively survey X-irradiated DNA for covalently linked tandem lesions. A total of 15 tandem lesions were detected in DNA irradiated in deoxygenated aqueous solution, five tandem lesions were detected in DNA that was irradiated in oxygenated solution. PMID:23106212

Patrzyc, Helen B; Dawidzik, Jean B; Budzinski, Edwin E; Freund, Harold G; Wilton, John H; Box, Harold C

2012-10-29

49

Simultaneous determination of norethindrone and ethinyl estradiol in human plasma by high performance liquid chromatography with tandem mass spectrometry—experiences on developing a highly selective method using derivatization reagent for enhancing sensitivity  

Microsoft Academic Search

In the present work, for the first time, a liquid chromatographic method with tandem mass spectrometric detection (LC–MS\\/MS) for the simultaneous analysis of norethindrone, and ethinyl estradiol, was developed and validated over the concentration range of 50–10000pg\\/ml and 2.5–500pg\\/ml, respectively, using 0.5ml of plasma sample. Norethindrone, ethinyl estradiol, and their internal standards norethindrone-13C2, and ethinyl estradiol-d4, were extracted from human

Wenkui Li; Ying-He Li; Austin C. Li; Shaolian Zhou; Weng Naidong

2005-01-01

50

Tandem Terminal Ion Source  

SciTech Connect

OAK-B135 Tandem Terminal Ion Source. The terminal ion source (TIS) was used in several experiments during this reporting period, all for the {sup 7}Be({gamma}){sup 8}B experiment. Most of the runs used {sup 1}H{sup +} at terminal voltages from 0.3 MV to 1.5 MV. One of the runs used {sup 2}H{sup +} at terminal voltage of 1.4 MV. The other run used {sup 4}He{sup +} at a terminal voltage of 1.37 MV. The list of experiments run with the TIS to date is given in table 1 below. The tank was opened four times for unscheduled source repairs. On one occasion the tank was opened to replace the einzel lens power supply which had failed. The 10 kV unit was replaced with a 15 kV unit. The second time the tank was opened to repair the extractor supply which was damaged by a tank spark. On the next occasion the tank was opened to replace a source canal which had sputtered away. Finally, the tank was opened to replace the discharge bottle which had been coated with aluminum sputtered from the exit canal.

None

2000-10-23

51

Curcumin prevents shock-wave lithotripsy-induced renal injury through inhibition of nuclear factor kappa-B and inducible nitric oxide synthase activity in rats.  

PubMed

Shock wave lithotripsy (SWL) is commonly used for treatment of renal stones. Free oxygen radicals are involved in the pathophysiology of renal injury due to SWL. We investigated the protective effects of curcumin, which is an antioxidant and nuclear factor kappa-B (NF-kappaB) inhibitor, against renal injury. Forty-eight rats were included and divided into four groups: group 1, control; group 2, SWL (15 kW-1,500 shocks); group 3, SWL + curcumin (curcumin orally 75 mg/kg/day dissolved in 10% ethyl alcohol, 1 day before and 5 days after SWL); and group 4, SWL + vehicle (10% ethyl alcohol). The kidneys were removed on days 7 and 35 after SWL. A sample was fixed in formaldehyde solution. Renal tissues were examined for proximal tubular injury under light microscope. iNOS activity and active subunit of NF-kappaB, p65, were evaluated immunohistochemically using rat monoclonal antibodies interpreting results semiquantitatively. There were significant differences between SWL and control groups on days 7 and 35, considering histological changes under light microscope (P < 0.02). There was a significant decrease in necrosis and fibrosis in the curcumin group as compared to the SWL group. Expressions of iNOS and p65 on days 7 and 35 were at basal levels with immunohistochemical staining. These parameters had high levels in the SWL group (P < 0.02). No significant difference was present between the control and the curcumin groups (P > 0.02). Curcumin, decreasing expressions of iNOS and p65 and serum nitric oxide levels prevented interstitial, glomerular, tubular epithelial and endothelial cellular injuries. We suggest that curcumin, could be used, especially in high-risk patients, as a protective agent to prevent renal injury due to SWL. PMID:19340419

Bas, Muzaffer; Tugcu, Volkan; Kemahli, Eray; Ozbek, Emin; Uhri, Mehmet; Altug, Tuncay; Tasci, Ali I

2009-04-02

52

Characterization of osteoprotegerin binding to glycosaminoglycans by surface plasmon resonance: Role in the interactions with receptor activator of nuclear factor {kappa}B ligand (RANKL) and RANK  

SciTech Connect

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor {kappa}B ligand (RANKL), a key inducer of osteoclastogenesis via its receptor RANK. We previously showed that RANK, RANKL, and OPG are able to form a tertiary complex and that OPG must be also considered as a direct effector of osteoclast functions. As OPG contains a heparin-binding domain, the present study investigated the interactions between OPG and glycosaminoglycans (GAGs) by surface plasmon resonance and their involvement in the OPG functions. Kinetic data demonstrated that OPG binds to heparin with a high-affinity (K {sub D}: 0.28 nM) and that the pre-incubation of OPG with heparin inhibits in a dose-dependent manner the OPG binding to the complex RANK-RANKL. GAGs from different structure/origin (heparan sulfate, dermatan sulfate, and chondroitin sulfate) exert similar activity on OPG binding. The contribution of the sulfation pattern and the size of the oligosaccharide were determined in this inhibitory mechanism. The results demonstrated that sulfation is essential in the OPG-blocking function of GAGs since a totally desulfated heparin loses its capacity to bind and to block OPG binding to RANKL. Moreover, a decasaccharide is the minimal structure that totally inhibits the OPG binding to the complex RANK-RANKL. Western blot analysis performed in 293 cells surexpressing RANKL revealed that the pre-incubation of OPG with these GAGs strongly inhibits the OPG-induced decrease of membrane RANKL half-life. These data support an essential function of the related glycosaminoglycans heparin and heparan sulfate in the activity of the triad RANK-RANKL-OPG.

Theoleyre, S. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Kwan Tat, S. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Vusio, P. [IFR26, Institut de Biologie, Nantes Hospital (France); Blanchard, F. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Gallagher, J. [Department of Medical Oncology, PICR, Christie Hospital NHS Trust, Wilmslow Rd, Manchester M20 4BX (United Kingdom); Ricard-Blum, S. [CNRS, UMR 5086, UCBL, Institut de Biologie et Chimie des Proteines, 7 passage du Vercors 69367 Lyon Cedex 07 (France); Fortun, Y. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Universite d'Angers, IUT (France); Padrines, M. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Redini, F. [INSERM, ERI 7, Nantes, F-44035 (France); Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France); Heymann, D. [INSERM, ERI 7, Nantes, F-44035 (France) and Universite de Nantes, Laboratoire de Physiopathologie de la Resorption Osseuse et Therapie des Tumeurs Osseuses Primitives, EA3822, Nantes F-44035 (France)]. E-mail: dominique.heymann@univ-nantes.fr

2006-08-25

53

Interleukin-4 and interleukin-10 modulate nuclear factor kappaB activity and nitric oxide synthase-2 expression in Theiler's virus-infected brain astrocytes.  

PubMed

In brain astrocytes, nuclear factor kappaB (NF-kappaB) is activated by stimuli that produce cellular stress causing the expression of genes involved in defence, including the inducible nitric oxide synthase (NOS-2). Theiler's murine encephalomyelitis virus (TMEV) induces a persistent CNS infection and chronic immune-mediated demyelination, similar to human multiple sclerosis. The cytokines interleukin (IL)-4 and IL-10 inhibit the expression of proinflammatory cytokines, counteracting the inflammatory process. Our study reports that infection of cultured astrocytes with TMEV resulted in a time-dependent phosphorylation of IkappaBalpha, degradation of IkappaBalpha and IkappaBbeta, activation of NF-kappaB and expression of NOS-2. The proteasome inhibitor MG-132 blocked TMEV-induced nitrite accumulation, NOS-2 mRNA expression and phospho-IkappaBalpha degradation, suggesting NF-kappaB-dependent NOS-2 expression. Pretreatment of astrocytes with IL-4 or IL-10 decreased p65 nuclear translocation, NF-kappaB binding activity and NOS-2 transcription. IL-4 and IL-10 caused an accumulation of IkappaBalpha in TMEV-infected astrocytes without affecting IkappaBbeta levels. The IkappaB kinase activity and the degradation rate of both IkappaBs were not modified by either cytokine, suggesting de novo synthesis of IkappaBalpha. Indeed, IL-4 or IL-10 up-regulated IkappaBalpha mRNA levels after TMEV infection. Therefore, the accumulation of IkappaBalpha might impair the translocation of the NF-kappaB to the nucleus, mediating the inhibition of NF-kappaB activity. Overall, these data suggest a novel mechanism of action of IL-4 and IL-10, which abrogates NOS-2 expression in viral-infected glial cells. PMID:12068072

Molina-Holgado, Eduardo; Arévalo-Martín, Angel; Castrillo, Antonio; Boscá, Lisardo; Vela, José M; Guaza, Carmen

2002-06-01

54

Alpha-lipoic acid suppresses osteoclastogenesis despite increasing the receptor activator of nuclear factor kappaB ligand/osteoprotegerin ratio in human bone marrow stromal cells.  

PubMed

Growing evidence has shown a biochemical link between increased oxidative stress and reduced bone density. Although alpha-lipoic acid (alpha-LA) has been shown to act as a thiol antioxidant, its effect on bone cells has not been determined. Using proteomic analysis, we identified six differentially expressed proteins in the conditioned media of alpha-LA-treated human bone marrow stromal cell line (HS-5). One of these proteins, receptor activator of nuclear factor kappaB ligand (RANKL), was significantly up-regulated, as confirmed by immunoblotting with anti-RANKL antibody. ELISA showed that alpha-LA stimulated RANKL production in cellular extracts (membranous RANKL) about 5-fold and in conditioned medium (soluble RANKL) about 23-fold, but had no effect on osteoprotegerin (OPG) secretion. Despite increasing the RANKL/OPG ratio, alpha-LA showed a dose-dependent suppression of osteoclastogenesis, both in a coculture system of mouse bone marrow cells and osteoblasts and in a mouse bone marrow cell culture system, and reduced bone resorption in a dose-dependent manner. In addition, alpha-LA-induced soluble RANKL was not inhibited by matrix metalloprotease inhibitors, indicating that soluble RANKL is produced by alpha-LA without any posttranslational processing. In contrast, alpha-LA had no significant effect on the proliferation and differentiation of HS-5 cells. These results suggest that alpha-LA suppresses osteoclastogenesis by directly inhibiting RANKL-RANK mediated signals, not by mediating cellular RANKL production. In addition, our findings indicate that alpha-LA-induced soluble RANKL is not produced by shedding of membranous RANKL. PMID:15930166

Koh, Jung-Min; Lee, Young-Sun; Byun, Chang-Hyun; Chang, Eun-Ju; Kim, Hyunsoo; Kim, Yong Hee; Kim, Hong-Hee; Kim, Ghi Su

2005-06-01

55

Cytochrome P450 1A1 gene regulation by UVB involves crosstalk between the aryl hydrocarbon receptor and nuclear factor kappaB.  

PubMed

UVB induces the expression of genes controlled by the aryl hydrocarbon receptor (AhR), a transcription factor that has been implicated in the UV stress response. In this study, we used the human hepatoma cell line HepG2 to investigate in more detail the effects of UVB irradiation on AhR activation and induction of cytochrome P450 1A1 (CYP1A1), a highly AhR-responsive gene. The CYP1A1 enzyme efficiently degrades 6-formylindolo[3,2-b]carbazole (FICZ), a high affinity ligand and suggested endogenous activator of the AhR. We show that physiologically relevant doses of UVB suppress CYP1A1 gene expression immediately after irradiation, but induce its expression later in an AhR-dependent manner. The initial repression phase of CYP1A1 transcription was mediated by another UVB-inducible transcription factor, the nuclear factor kappaB (NFkappaB). Crosstalk between AhR and NFkappaB signaling has earlier been implicated to control CYP1A1 expression following stimulation by xenobiotics and cytokines. Now, our findings clearly indicate a role of NFkappaB also in UVB-dependent AhR signaling. We also observed that UVB reduced the catalytic activity of the CYP1A1 enzyme. Thereby, UVB attenuated the clearance of FICZ, which led to prolonged AhR activation. We further noted that repeated irradiation with UVB or H(2)O(2) treatment shifted the cells into a refractory state in which AhR signaling could not be efficiently activated by UVB or H(2)O(2), but by ligands. Together, our results suggest that the NFkappaB-mediated initial suppression of CYP1A1 as well as the unresponsiveness of AhR signaling to repeated irradiation may be part of a protective cellular UV stress response. PMID:20132803

Luecke, S; Wincent, E; Backlund, M; Rannug, U; Rannug, A

2010-02-01

56

Osteopontin is associated with nuclear factor {kappa}B gene expression during tail-suspension-induced bone loss  

SciTech Connect

Osteoporosis due to unloading-induced bone loss is a critical issue in the modern aging society. Although the mechanisms underlying this phenomenon are largely unknown, osteopontin (OPN) is one of the critical mediators required for unloading-induced bone loss [M. Ishijima, S.R. Rittling, T. Yamashita, K. Tsuji, H. Kurosawa, A. Nifuji, D.T. Denhardt, and M. Noda, Enhancement of osteoclastic bone resorption and suppression of osteoblastic bone formation in response to reduced mechanical stress do not occur in the absence of osteopontin, J Exp Med, 193 (2001) 399-404]. To clarify the molecular bases for OPN actions, we carried out microarray analyses on the genes expressed in the femoral bone marrow cells in wild type and OPN-/- mice. The removal of the mechanical load induced bone loss in wild type, but not in OPN-/- mice, as previously reported. Expression analysis of 9586 cDNAs on a microarray system revealed that OPN deficiency blocked tail-suspension-induced expression of ten genes (group A). This observation was confirmed based on semi-quantitative RT-PCR analyses. On the other hand, expression of four genes (group B) was not altered by tail suspension in wild type but was enhanced in OPN-deficient mice. NF-{kappa}B p105 subunit gene (Nfkb1) was found in group A and Bax in group B. p53 gene expression was upregulated by tail suspension in wild type mice, but it was no longer observed in OPN-/- mice. These data indicate that OPN acts to mediate mechanical stress signaling upstream to the genes encoding apoptosis-related molecules, and its action is associated with alteration of the genes.

Ishijima, Muneaki [Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 3-10, Kanda-Surugadai 2-Chome, Chiyoda-Ku, Tokyo 101-0062 (Japan); Ezura, Yoichi [Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 3-10, Kanda-Surugadai 2-Chome, Chiyoda-Ku, Tokyo 101-0062 (Japan) and Department of Molecular Biology, Institute of Gerontology, Nippon Medical School, Kawasaki (Japan)]. E-mail: ezura.mph@mril.tmd.ac.jp; Tsuji, Kunikazu [Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, 3-10, Kanda-Surugadai 2-Chome, Chiyoda-Ku, Tokyo 101-0062 (Japan)] (and others)

2006-10-01

57

Microstability of the TMX Tandem Mirror Experiments.  

National Technical Information Service (NTIS)

In the tandem mirror device, an efficient source of warm ions, the central cell, is available for stabilization of ion loss-cone instabilities. These instabilities previously limited ion confinement in single-cell mirror experiments. In the simple tandem ...

T. A. Casper L. V. Berzins

1987-01-01

58

Monolithic hybrid tandem solar cells comprising copper indium gallium diselenide and organic subcells  

NASA Astrophysics Data System (ADS)

Combining wide and narrow band gap absorbers in tandem solar cells is a promising approach to improve the energy conversion of sun light. In this work, we present hybrid tandem devices comprising monolithically connected copper indium gallium diselenide (CIGS) bottom cells and polymer top cells. The thin polymer:fullerene bulk heterojunction absorber layers were transferred onto the rough CIGS surface by a soft-contact lamination technique. Sputtered or solution-deposited top cathodes complete the tandem devices with enhanced open circuit voltages.

Reinhard, Manuel; Sonntag, Paul; Eckstein, Ralph; Bürkert, Linda; Bauer, Andreas; Dimmler, Bernhard; Lemmer, Uli; Colsmann, Alexander

2013-09-01

59

Suppression of metastasis by nuclear factor kappaB inhibitors in an in vivo lung metastasis model of chemically induced hepatocellular carcinoma.  

PubMed

To evaluate the suppressive effects of nuclear factor kappa B (NF-kappaB) inhibitors on metastasis, three agents, pentoxifylline (PTX, 0.5% in diet), N-acetyl-L-cysteine (NAC, 0.5% in diet), and aspirin (ASP, 0.5% in diet) were applied in an in vivo highly metastatic rat hepatocellular carcinoma (HCC) model in F344 male rats. Administration of NF-kappaB inhibitors for 8 weeks after induction of highly metastatic HCC by sequential treatment with diethylnitrosamine and N-nitrosomorpholine did not cause any significant change in survival rate or body weight. The incidence of HCC was 100% at week 23, regardless of treatment with NF-kappaB inhibitors. PTX, NAC, and ASP did not exert any significant effect on the development or differentiation of HCCs, although PTX tended to decrease the multiplicity of HCC. Although no lung metastasis was observed in the rats killed at the end of the period of carcinogen exposure, lung metastasis was found in 100% of animals in all the groups at the end of the experiment. Multiplicity of lung metastasis was significantly decreased by PTX and NAC, whereas ASP was without significant influence. The size of metastatic nodules was also significantly reduced in the PTX treatment group. Furthermore, the inhibitory kappa-B (IkappaB) protein level, considered to be a marker for the degree of NF-kappaB transcription, was significantly suppressed by PTX. mRNA expression in HCC for vascular cell adhesion molecule-1 (VCAM-1), which is considered to play a key role in attachment of cancer cells to the endothelium, was significantly suppressed by PTX. Among the splicing variants of VEGF, VEGF-A120, VEGF-A144, VEGF-A164, and VEGF-A188, suppressed mRNA expression of VEGF-A188 appeared to be correlated with suppression of lung metastasis formation. In conclusion, the present study demonstrated that NF-kappaB inhibitors have the potential to inhibit lung metastasis from rat HCCs in vivo, and PTX is especially promising. Its mechanism of action may involve suppression of VCAM-1 and VEGF-A188 production. PMID:14720322

Futakuchi, Mitsuru; Ogawa, Kumiko; Tamano, Seiko; Takahashi, Seishiro; Shirai, Tomoyuki

2004-01-01

60

Tandem Mass Spectrometry in Physiology  

NSDL National Science Digital Library

Tandem mass spectrometry coupled to liquid chromatography (LC-MS/MS) allows identification of proteins in a complex mixture without need for protein purification ("shotgun" proteomics). Recent progress in LC-MS/MS-based quantification, phosphoproteomic analysis, and targeted LC-MS/MS using multiple reaction monitoring (MRM) has made LC-MS/MS a powerful tool for the study of cell physiology.

2007-12-01

61

Tandem motors increase well bore penetration rate  

SciTech Connect

Running a positive displacement downhole motor with tandem power sections and the proper bit significantly increases the rate of penetration and reduces stalling problems. The use of positive displacement mud motors (PDMs) with two power sections has improved penetration rates on a number of drilling applications in western Canada. The majority of all the tandem motor runs to date have been successful. Results of these tandem runs show that tandem motors should be considered in any situation where a single motor is run. This paper reviews the performance of tandem motors at several case sites. It describes the design, rate of penetration, bit selection, mud systems, and use in horizontal wells.

Matthews, S. [Halliburton Drilling Systems, Calgary, Alberta (Canada); McCosh, R. [CenAlta Well Services Inc., Calgary, Alberta (Canada)

1996-02-26

62

The regulatory tandem domains of human phosphodiesterases 1 and 4 regulate a cyanobacterial adenylyl cyclase.  

PubMed

Human phosphodiesterase 1 is regulated by a tandem of N-terminal calmodulin/Ca(2+)-binding domains. We grafted the tandems from hPDE1A3 and -B1 onto the cyanobacterial adenylyl cyclase CyaB1 thus replacing an intrinsic tandem GAF-domain. Cyclase activity was stimulated by Ca(2+)/calmodulin 1.9 to 4.4-fold, i.e. similarly as reported for hPDE1 regulation. hPDE4 long isoforms are activated by phosphorylation of a serine located in a conserved RRESF motif in a tandem of N-terminal upstream-conserved regions (UCR). We grafted the UCR tandems from hPDE4A4, -B1, and -D3 onto the CyaB1 cyclase as a reporter enzyme. Activity was enhanced 1.4 to 4.5-fold by respective phosphomimetic (S/D) point mutations. Similarly, cyclase activity was increased 2.5-fold by phosphorylation of the chimera with the PDE4D3 UCR tandem by cAMP-dependent protein kinase. We propose a common mechanism of activation in mammalian phosphodiesterases containing N-terminal tandem regulatory domains. A downstream region is suggested to alternate between random and ordered conformations and to enable switching between inactive, the catalytic domain occluding PDE homodimers and active monomeric PDE catalytic domains. PMID:22484154

Banjac, Ana; Kurz, Ursula; Schultz, Joachim E

2012-03-30

63

Tandem motors reduce well costs  

SciTech Connect

The new generation of tandem mud motors that recently appeared on the drilling scene is significantly affecting drilling efficiency worldwide. These motors provide drillers with increased horsepower at the bit, higher torque, and faster rates of penetration (ROP). With advanced engineering and more durable materials, motor life is being extended, thereby increasing the time between bit trips and reducing drilling costs. This article reviews the performance, design, and operation of these motors.

Hooper, M.; Daigle, C. [Halliburton Energy Services, Houston, TX (United States); Crowe, R. [Halliburton Energy Services, Aberdeen (United Kingdom)

1995-10-01

64

Results of Research on Tandem and Tip-Attached Tandem Propellers.  

National Technical Information Service (NTIS)

An investigation was made into the potential benefits of tandem propellers and tip-attached tandem propellers. Design calculations using lifting line and lifting surface theory were used, and model propellers were tested in open water. Two sets were teste...

J. B. Hadler P. C. Pien

1985-01-01

65

Detecting long tandem duplications in genomic sequences  

PubMed Central

Background Detecting duplication segments within completely sequenced genomes provides valuable information to address genome evolution and in particular the important question of the emergence of novel functions. The usual approach to gene duplication detection, based on all-pairs protein gene comparisons, provides only a restricted view of duplication. Results In this paper, we introduce ReD Tandem, a software using a flow based chaining algorithm targeted at detecting tandem duplication arrays of moderate to longer length regions, with possibly locally weak similarities, directly at the DNA level. On the A. thaliana genome, using a reference set of tandem duplicated genes built using TAIR,a we show that ReD Tandem is able to predict a large fraction of recently duplicated genes (dS?tandem duplications involving non coding elements such as pseudo-genes or RNA genes. Conclusions ReD Tandem allows to identify large tandem duplications without any annotation, leading to agnostic identification of tandem duplications. This approach nicely complements the usual protein gene based which ignores duplications involving non coding regions. It is however inherently restricted to relatively recent duplications. By recovering otherwise ignored events, ReD Tandem gives a more comprehensive view of existing evolutionary processes and may also allow to improve existing annotations.

2012-01-01

66

14 CFR 23.302 - Canard or tandem wing configurations.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Canard or tandem wing configurations. 23.302 Section...General § 23.302 Canard or tandem wing configurations. The forward structure of a canard or tandem wing configuration must:...

2010-01-01

67

14 CFR 23.302 - Canard or tandem wing configurations.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Canard or tandem wing configurations. 23.302 Section...General § 23.302 Canard or tandem wing configurations. The forward structure of a canard or tandem wing configuration must:...

2009-01-01

68

14 CFR 23.302 - Canard or tandem wing configurations.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Canard or tandem wing configurations. 23.302 Section...General § 23.302 Canard or tandem wing configurations. The forward structure of a canard or tandem wing configuration must:...

2013-01-01

69

In vivo and in vitro analysis of the human tissue-type plasminogen activator gene promoter in neuroblastomal cell lines: evidence for a functional upstream kappaB element.  

PubMed

Besides its well-established role in wound healing and fibrinolysis, tissue-type plasminogen activator (t-PA) has been shown to contribute to cognitive processes and memory formation within the central nervous system, and to promote glutamate receptor-mediated excitotoxicity. The t-PA gene is expressed and regulated in neuronal cells but the regulatory transcriptional processes directing this expression are still poorly characterized. We have used DNase I-hypersensitivity mapping and in vivo foot printing to identify putative regulatory elements and transcription factor binding sites in two human neuroblastomal (KELLY and SK-N-SH) and one human glioblastomal (SNB-19) cell lines. Hypersensitive sites were found in the proximal promoter region of all cell lines, and within the first exon for KELLY and SNB-19 cells. Mapping of methylation-protected residues in vivo detected a cluster of protected residues corresponding to a cAMP response element (CRE) and Sp1 sites in the proximal promoter previously shown to be essential for basal expression in other cell types. Protected residues were also found at other sites, notably a kappaB element at position bp -3081 to -3072 that was partly protected in KELLY and SNB-19 cells. Analysis of transfected reporter constructs in KELLY and SNB-19 cells confirmed that this particular element is functionally significant in the transactivation of the t-PA promoter in both cell types. This study defines, by in vivo and in vitro methods, a previously undescribed kappaB site in the t-PA gene promoter that influences t-PA expression in neuronal cells. PMID:15869598

Lux, W; Klobeck, H-G; Daniel, P B; Costa, M; Medcalf, R L; Schleuning, W-D

2005-05-01

70

Improved monolithic tandem solar cell  

DOEpatents

A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surf ace of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched.

Wanlass, M.W.

1991-04-23

71

Locomotion by Tandem and Parallel Wings  

Microsoft Academic Search

A two-dimensional analysis was carried out on the locomotion by tandem and parallel wings in relation to the free flight of dragonflies and beetles, remarking the mutual interference between fore and hind wings. The results obtained are summarized as follows: In the case of tandem wings, (1)High thrust and propulsive efficiency can be achieved when the forewing oscillates with a

Yoshimichi Tanida

2003-01-01

72

Survey of plant short tandem DNA repeats  

Microsoft Academic Search

Length variations in simple sequence tandem repeats are being given increased attention in plant genetics. Some short tandem repeats (STRs) from a few plant species, mainly those at the dinucleotide level, have been demonstrated to show polymorphisms and Mendelian inheritance. In the study reported here a search for all of the possible STRs ranging from mononucleotide up to tetranucleotide repeats

Z. Wang; J. L. Weber; G. Zhong; S. D. Tanksley

1994-01-01

73

Finding approximate tandem repeats in genomic sequences  

Microsoft Academic Search

An efficient algorithm is presented for detecting approximate tandem repeats in genomic sequences. The algorithm is based on a flexible statistical model which allows a wide range of definitions of approximate tandem repeats. The ideas and methods underlying the algorithm are described and examined and its effectiveness on genomic data is demonstrated.

Ydo Wexler; Zohar Yakhini; Yechezkel Kashi; Dan Geiger

2004-01-01

74

Hydrodynamic studies on two traveling wavy foils in tandem arrangement  

NASA Astrophysics Data System (ADS)

In this study, the hydrodynamic interactions between two tandem foils undergoing fishlike swimming motion are investigated numerically by solving the Navier-Stokes equations with the immersed-boundary method. The two foils represent two tandem propellers attached on a concept ship. The thrusts and efficiencies at three typical Strouhal numbers, i.e., St=0.4, 0.6, and 0.8, are investigated. The results show that a fish situated directly behind another one does not always undergo a lower thrust. Whether it experiences a thrust enhancement or reduction depends on the Strouhal number. At a relatively low Strouhal number (e.g., St=0.4), the usual wake drag-reduction effect predominates over the drag-enhancement effect caused by the reverse von Kármán vortices, resulting in a thrust enhancement. The opposite happens at a relatively high Strouhal number (e.g., St=0.8). The downstream fish can benefit from the upstream one by slalom between the vortices rather than through them. For the upstream fish, the thrusts and efficiencies for all Strouhal numbers studied are higher than those for a single fish when the two fish are closely spaced, and approach those for a single fish as the spacing is increased.

Deng, Jian; Shao, Xue-Ming; Yu, Zhao-Sheng

2007-11-01

75

Tandem triad systems based on FRET for two-photon induced release of glutamate.  

PubMed

Tandem systems allowing enhanced two-photon (2P) absorption in a wavelength range permitting coupling of the primary excitation by energy transfer to an intramolecular cage known to have fragmentation properties suited to photolysis in neuroscience is demonstrated to lead to a 10-fold improvement in the 2P photolysis cross-section at experimentally compatible wavelengths. PMID:24108351

Picard, Sébastien; Cueto-Diaz, Eduardo Jose; Genin, Emilie; Clermont, Guillaume; Acher, Francine; Ogden, David; Blanchard-Desce, Mireille

2013-10-24

76

Efficient tandem organic light-emitting device based on photovoltaic-type connector with positive cycle  

NASA Astrophysics Data System (ADS)

We designed a tandem organic light-emitting device based on an organic photovoltaic-type charge generation connector (CGC) of fullerene carbon 60/copper(II) phthalocyanine. The CGC can absorb a portion of photons radiated from emission zone and form excitons which disassociated into free charges at PN junction interface without energy barrier, leading to low driving voltage and better charge balance. The efficiency increases remarkably with increasing current density, even beyond two folds compared with single unit device under higher current density, meaning slower roll-off. The whole process is a positive cycle, and actually enhances the utilization of internal radiation and the overall performance of tandem device.

Liu, Huihui; Yan, Fei; Wang, Hua; Miao, Yanqin; Du, Xiaogang; Jing, Shu; Gao, Zhixiang; Chen, Liuqing; Hao, Yuying; Xu, Bingshe

2013-01-01

77

Oak Ridge 25-MV tandem accelerator  

SciTech Connect

A brief description is presented of the scope and status of the heavy ion accelerator facility, and status of the project is discussed. Initial operation of the 25 MV tandem accelerator from National Electrostatics Corporation is covered. (GHT)

Jones, C.M.

1981-01-01

78

Restriction Endonucleases/Variable Number Tandem Repeats.  

National Technical Information Service (NTIS)

Lecture I - Restriction Endonucleases by B. Howard, NIH, describes action of restriction endonucleases, nomenclature, availability of these materials, and certain difficulties. Lecture II - Variable Number Tandem Repeats (VNTR) by S. Odelberg, University ...

1994-01-01

79

Fractalkine (CX3CL1) stimulated by nuclear factor kappaB (NF-kappaB)-dependent inflammatory signals induces aortic smooth muscle cell proliferation through an autocrine pathway.  

PubMed

Fractalkine (also known as CX3CL1), a CX3C chemokine, activates and attracts monocytes/macrophages to the site of injury/inflammation. It binds to CX3C receptor 1 (CX3CR1), a pertussis toxin-sensitive G-protein-coupled receptor. In smooth muscle cells (SMCs), fractalkine is induced by proinflammatory cytokines [tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma)], which may mediate monocyte adhesion to SMCs. However, the mechanisms underlying its induction are unknown. In addition, it is unlear whether SMCs express CX3CR1. TNF-alpha activated nuclear factor kappaB (NF-kappaB) and induced fractalkine and CX3CR1 expression in a time-dependent manner in rat aortic SMCs. Transient transfections with dominant-negative (dn) inhibitory kappaB (IkappaB)-alpha, dnIkappaB-beta, dnIkappaB kinase (IKK)-gamma, kinase-dead (kd) NF-kappaB-inducing kinase (NIK) and kdIKK-beta, or pretreatment with wortmannin, Akt inhibitor, pyrrolidinecarbodithioc acid ammonium salt ('PDTC') or MG-132, significantly attenuated TNF-alpha-induced fractalkine and CX3CR1 expression. Furthermore, expression of dn TNF-alpha-receptor-associated factor 2 (TRAF2), but not dnTRAF6, inhibited TNF-alpha signal transduction. Pretreatment with pertussis toxin or neutralizing anti-CX3CR1 antibodies attenuated TNF-alpha-induced fractalkine expression, indicating that fractalkine autoregulation plays a role in TNF-alpha-induced sustained fractalkine expression. Fractalkine induced its own expression, via pertussis toxin-sensitive G-proteins, phosphoinositide 3-kinase (PI 3-kinase), phosphoinositide-dependent kinase 1 (PDK1), Akt, NIK, IKK and NF-kappaB activation, and induced SMC cell-cell adhesion and cellular proliferation. Taken together, our results demonstrate that TNF-alpha induces the expression of fractalkine and CX3CR1 in rat aortic SMCs and that this induction is mediated by NF-kappaB activation. We also show that fractalkine induces its own expression, which is mediated by the PI 3-kinase/PDK1/Akt/NIK/IKK/NF-kappaB signalling pathway. More importantly, fractalkine increased cell-cell adhesion and aortic SMC proliferation, indicating a role in initiation and progression of atherosclerotic vascular disease. PMID:12729461

Chandrasekar, Bysani; Mummidi, Srinivas; Perla, Rao P; Bysani, Sailaja; Dulin, Nickolai O; Liu, Feng; Melby, Peter C

2003-07-15

80

Initial operation of ORIC with tandem injection  

SciTech Connect

Coupled operation of the 25 MV tandem and ORIC was achieved on January 27, 1981. The initial beam was 324 MeV /sup 16/O/sup 8 +/ followed shortly by oxygen at 400 MeV-the maximum design energy. Following additional installation and testing of the tandem, coupled operation for a nuclear physics experiment began in August. Performance of the system was in close agreement with that predicted from calculations.

Ludemann, C.A.; Ball, J.B.; Beckers, R.M.; Cleary, T.P.; Hudson, E.D.; Lord, R.S.; Martin, J.A.; Milner, W.T.; Mosko, S.W.; Ziegler, N.F.

1981-01-01

81

A novel tandem quadrupole mass analyzer  

Microsoft Academic Search

A new “tandem mass analyzer” is described. Two quadrupole mass filters are operated in series. Each is operated at low resolution\\u000a and a small mass offset is introduced between the two quadrupoles so that the pair operate together to give higher resolution.\\u000a The resolution of the tandem analyzer can be changed by changing the mass offset. The transmission is highest

Zhaohui Du; D. J. Douglas

1999-01-01

82

Activation of nuclear factor kappaB through the IKK complex by the topoisomerase poisons SN38 and doxorubicin: a brake to apoptosis in HeLa human carcinoma cells.  

PubMed

The transcription factor nuclear factor (NF) kappaB is involved in the regulation of cell survival. NFkappaB is activated in many malignant tumors and seems to play a role in the resistance to cytostatic treatments and escape from apoptosis. We have studied the effects on NFkappaB activation of two topoisomerase poisons and DNA damaging agents that are used in chemotherapy: SN38 (7-ethyl-10-hydroxycamptothecin), the active metabolite of CPT11, and doxorubicin. In HeLa cells, both drugs activate NFkappaB using a preexisting pathway that requires a functional IkappaB-specific kinase complex, IkappaB-specific kinase activation, IkappaB-alpha phosphorylation, and degradation. Blocking NFkappaB activation by stable expression of a mutant super-repressor IkappaB-alpha molecule sensitized HeLa cells to the apoptotic actions of drugs and tumor necrosis factor. RNase protection assay analysis demonstrate that NFkappaB is involved in the regulation of a complex pattern of gene activation and repression during the cellular response of HeLa cells to topoisomerase poisons. The blockade of NF-kappaB activation seems to shift the death/survival balance toward apoptosis. PMID:11691793

Bottero, V; Busuttil, V; Loubat, A; Magné, N; Fischel, J L; Milano, G; Peyron, J F

2001-11-01

83

Small GTPase Rho signaling is involved in {beta}1 integrin-mediated up-regulation of intercellular adhesion molecule 1 and receptor activator of nuclear factor {kappa}B ligand on osteoblasts and osteoclast maturation  

SciTech Connect

We assessed the characteristics of human osteoblasts, focusing on small GTPase Rho signaling. {beta}1 Integrin were highly expressed on osteoblasts. Engagement of {beta}1 integrins by type I collagen augmented expression of intercellular adhesion molecule 1 (ICAM-1) and receptor activator of nuclear factor {kappa}B ligand (RANKL) on osteoblasts. Rho was activated by {beta}1 stimulation in osteoblasts. {beta}1 Integrin-induced up-regulation of ICAM-1 and RANKL was inhibited by transfection with adenoviruses encoding C3 transferase or pretreated with Y-27632, specific Rho and Rho-kinase inhibitors. Engagement of {beta}1 integrin on osteoblasts induced formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNC) in a coculture system of osteoblasts and peripheral monocytes, but this action was completely abrogated by transfection of C3 transferase. Our results indicate the direct involvement of Rho-mediated signaling in {beta}1 integrin-induced up-regulation of ICAM-1 and RANKL and RANKL-dependent osteoclast maturation. Thus, Rho-mediated signaling in osteoblasts seems to introduce major biases to bone resorption.

Hirai, Fumihiko [First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555 (Japan); Nakayamada, Shingo [First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555 (Japan); Okada, Yosuke [First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555 (Japan); Saito, Kazuyoshi [First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555 (Japan); Kurose, Hitoshi [Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Mogami, Akira [Pharmaceuticals Research Unit Research and Development Division Mitsubishi Pharma Corporation, Kamoshida-cho, Aoba-ku, Yokohama 227-0033 (Japan); Tanaka, Yoshiya [First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555 (Japan)]. E-mail: tanaka@med.uoeh-u.ac.jp

2007-04-27

84

Microevolution of Cryptococcus neoformans driven by massive tandem gene amplification.  

PubMed

The subtelomeric regions of organisms ranging from protists to fungi undergo a much higher rate of rearrangement than is observed in the rest of the genome. While characterizing these ~40-kb regions of the human fungal pathogen Cryptococcus neoformans, we have identified a recent gene amplification event near the right telomere of chromosome 3 that involves a gene encoding an arsenite efflux transporter (ARR3). The 3,177-bp amplicon exists in a tandem array of 2-15 copies and is present exclusively in strains with the C. neoformans var. grubii subclade VNI A5 MLST profile. Strains bearing the amplification display dramatically enhanced resistance to arsenite that correlates with the copy number of the repeat; the origin of increased resistance was verified as transport-related by functional complementation of an arsenite transporter mutant of Saccharomyces cerevisiae. Subsequent experimental evolution in the presence of increasing concentrations of arsenite yielded highly resistant strains with the ARR3 amplicon further amplified to over 50 copies, accounting for up to ~1% of the whole genome and making the copy number of this repeat as high as that seen for the ribosomal DNA. The example described here therefore represents a rare evolutionary intermediate-an array that is currently in a state of dynamic flux, in dramatic contrast to relatively common, static relics of past tandem duplications that are unable to further amplify due to nucleotide divergence. Beyond identifying and engineering fungal isolates that are highly resistant to arsenite and describing the first reported instance of microevolution via massive gene amplification in C. neoformans, these results suggest that adaptation through gene amplification may be an important mechanism that C. neoformans employs in response to environmental stresses, perhaps including those encountered during infection. More importantly, the ARR3 array will serve as an ideal model for further molecular genetic analyses of how tandem gene duplications arise and expand. PMID:22334577

Chow, Eve W L; Morrow, Carl A; Djordjevic, Julianne T; Wood, Ian A; Fraser, James A

2012-02-14

85

Optimizing a tandem disk model  

SciTech Connect

A very simple physicomathematical model, in which thin straight blades with zero drag skim across a plane rectangular disk, shows that the maximum power coefficient attains the classical maximum of 0.593 over a range of T and a zero or small negative value of alpha/sub 0/. This maximum appears independent of sigma and there are values of T and alpha/sub 0/ for which the speed through the disk becomes complex and the model breaks down. Extending this model to a tandem disk system leads to a difficulty in defining the power coefficient. Attempts to optimize the system output based on reference areas A/sub 1/, A/sub 2/, and A/sub 4/ prove futile and the sum of the coefficients is chosen for this purpose. For thin blades and zero drag the analytic solution is available and it shows that the maximum value of 2 X 0.593 is attained over a narrow range of slightly negative alpha/sub 0/ (blade nose in) and medium values of T. The maximum is independent of sigma. As T is increased, the model breaks down either after C /SUB psum/ becomes large and negative or after backflow through the downwind disk occurs. There appears to be no requirement on load distribution between the disks. By comparison, modeling a machine with NACA 0012 blades at Re = 1.34 X 10/sup 6/ shows that the maximum value of C /SUB psum/ depends on the solidity. For example, at sigma = 0.4, the maximum value of C /SUB psum/ is 83% of 2 X 0.593. At such high values of sigma, however, the ranges of alpha/sub 0/ and T over which solutions are available become very limited.

Healey, J.V.

1983-07-01

86

Tandem repeats derived from centromeric retrotransposons  

PubMed Central

Background Tandem repeats are ubiquitous and abundant in higher eukaryotic genomes and constitute, along with transposable elements, much of DNA underlying centromeres and other heterochromatic domains. In maize, centromeric satellite repeat (CentC) and centromeric retrotransposons (CR), a class of Ty3/gypsy retrotransposons, are enriched at centromeres. Some satellite repeats have homology to retrotransposons and several mechanisms have been proposed to explain the expansion, contraction as well as homogenization of tandem repeats. However, the origin and evolution of tandem repeat loci remain largely unknown. Results CRM1TR and CRM4TR are novel tandem repeats that we show to be entirely derived from CR elements belonging to two different subfamilies, CRM1 and CRM4. Although these tandem repeats clearly originated in at least two separate events, they are derived from similar regions of their respective parent element, namely the long terminal repeat (LTR) and untranslated region (UTR). The 5? ends of the monomer repeat units of CRM1TR and CRM4TR map to different locations within their respective LTRs, while their 3? ends map to the same relative position within a conserved region of their UTRs. Based on the insertion times of heterologous retrotransposons that have inserted into these tandem repeats, amplification of the repeats is estimated to have begun at least ~4 (CRM1TR) and ~1 (CRM4TR) million years ago. Distinct CRM1TR sequence variants occupy the two CRM1TR loci, indicating that there is little or no movement of repeats between loci, even though they are separated by only ~1.4 Mb. Conclusions The discovery of two novel retrotransposon derived tandem repeats supports the conclusions from earlier studies that retrotransposons can give rise to tandem repeats in eukaryotic genomes. Analysis of monomers from two different CRM1TR loci shows that gene conversion is the major cause of sequence variation. We propose that successive intrastrand deletions generated the initial repeat structure, and gene conversions increased the size of each tandem repeat locus.

2013-01-01

87

Ant search strategies after interrupted tandem runs.  

PubMed

Tandem runs are a form of recruitment in ants. During a tandem run, a single leader teaches one follower the route to important resources such as sources of food or better nest sites. In the present study, we investigate what tandem leaders and followers do, in the context of nest emigration, if their partner goes missing. Our experiments involved removing either leaders or followers at set points during tandem runs. Former leaders first stand still and wait for their missing follower but then most often proceed alone to the new nest site. By contrast, former followers often first engage in a Brownian search, for almost exactly the time that their former leader should have waited for them, and then former followers switch to a superdiffusive search. In this way, former followers first search their immediate neighbourhood for their lost leader before becoming ever more wide ranging so that in the absence of their former leader they can often find the new nest, re-encounter the old one or meet a new leader. We also show that followers gain useful information even from incomplete tandem runs. These observations point to the important principle that sophisticated communication behaviours may have evolved as anytime algorithms, i.e. procedures that are beneficial even if they do not run to completion. PMID:20435821

Franks, Nigel R; Richardson, Thomas O; Keir, Samantha; Inge, Stephen J; Bartumeus, Frederic; Sendova-Franks, Ana B

2010-05-01

88

Tandem shock wave cavitation enhancement for extracorporeal lithotripsy  

Microsoft Academic Search

Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase

Achim M Loske; Fernando E Prieto; Francisco Fernández; Javier van Cauwelaert

2002-01-01

89

Structural basis for tandem L27 domain-mediated polymerization  

SciTech Connect

The establishment of epithelial cell polarity requires the assembly of multiprotein complexes and is crucial during epithelial morphogenesis. Three scaffolding proteins, Dlg1, MPP7, and Mals3, can be assembled to form a complex that functions in the establishment and maintenance of apicobasal polarity in epithelial tissues through their L27 domains. Here we report the crystal structure of a 4-L27-domain complex derived from the human tripartite complex Dlg1-MPP7-Mals3 in combination with paramagnetic relaxation enhancement measurements. The heterotrimer consists of 2 pairs of heterodimeric L27 domains. These 2 dimers are asymmetric due to the large difference between the N- and C-terminal tandem L27 domain of MPP7. Structural analysis combined with biochemical experiments further reveals that the loop {alpha}A-{alpha}B and helix {alpha}B of the C-terminal L27 domain of MPP7 play a critical role in assembling the entire tripartite complex, suggesting a synergistic tandem L27-mediated assembling event.

Yang, Xue; Xie, Xingqiao; Chen, Liu; Zhou, Hao; Wang, Zheng; Zhao, Weijing; Tian, Ran; Zhang, Rongguang; Tian, Changlin; Long, Jiafu; Shen, Yuequan (UST - China); (Nankai); (Chinese Aca. Sci.)

2010-12-01

90

47 CFR 69.129 - Signalling for tandem switching.  

Code of Federal Regulations, 2012 CFR

...CHARGES Computation of Charges § 69.129 Signalling for tandem switching. A charge that is expressed in dollars and cents shall be assessed upon the purchasing entity by a local telephone company for provision of signalling for tandem...

2012-10-01

91

Tandem mirror thermal barrier experimental program plan  

SciTech Connect

This report describes an experimental plan for the development of the Tandem Mirror Thermal Barrier. Included is: (1) a description of thermal barrier related physics experiments; (2) thermal barrier related experiments in the existing TMX and Phaedrus experiments; (3) a thermal barrier TMX upgrade; and (4) initiation of investigations of axisymmetric magnetic geometry. Experimental studies of the first two items are presently underway. Results are expected from the TMX upgrade by the close of 1981 and from axisymmetric tandem mirror experiments at the end of 1983. Plans for Phaedrus upgrades are developing for the same period.

Coensgen, F.H.; Drake, R.P.; Simonen, T.C.

1980-01-02

92

Tandem transformation of glycerol to esters.  

PubMed

Tandem transformation of glycerol via microbial fermentation and enzymatic esterification is presented. The reaction can be performed with purified waste glycerol from biodiesel production in a continuous mode, combining continuous fermentation with membrane-supported enzymatic esterification. Continuous anaerobic fermentation was optimized resulting in the productivity of 2.4 g L?¹ h?¹ of 1,3-propanediol. Biphasic esterification of 1,3-propanediol was optimized to achieve ester yield of up to 75%. A hollow fibre membrane contactor with immobilized Rhizomucor miehei lipase was demonstrated for the continuous tandem fermentation-esterification process. PMID:22796408

Sotenko, Maria V; Rebroš, Martin; Sans, Victor S; Loponov, Konstantin N; Davidson, Matthew G; Stephens, Gill; Lapkin, Alexei A

2012-07-13

93

Tandem organic photodetectors with tunable, broadband response  

NASA Astrophysics Data System (ADS)

Broadband photodetection is achieved by integrating three electron donor materials with complementary absorption into an organic photodetector (OPD). While a single donor-acceptor heterojunction can show broadband response, the spectral tunability is intrinsically limited to the absorption profiles of the active materials. Here, we demonstrate broadband OPDs consisting of multiple bulk heterojunctions arranged in tandem. These OPDs show high responsivity under moderate reverse bias from the ultraviolet to the near-infrared. By combining materials with complementary absorption in a tandem OPD, we demonstrate that the response from each band can be separately tuned with manipulation of the heterojunction thicknesses or composition.

Matthew Menke, S.; Pandey, Richa; Holmes, Russell J.

2012-11-01

94

Homicidal tandem bullet wound of the chest.  

PubMed

An unusual case of a homicidal gunshot wound to the chest is reported in which two bullets were fired in unison as tandem bullets from a handgun. At autopsy, two intact bullets were retrieved from the body of the victim, yet there was only one entrance wound and a single bullet track across the chest wall and thoracic organs. An examination of the weapon and ammunition supported the likelihood of tandem bullets and suggested the probable mechanism for this event. Very few similar cases have been documented. PMID:9095302

Bentley, A J; Busuttil, A; Clifton, B; Sibbald, P

1997-03-01

95

Tandem-mirror program: status and projection  

SciTech Connect

Construction of MFTF-B is scheduled for completion in 1985. Results of experiments in TMX-U and MFTF-B will permit the design of the D-T burning tandem-mirror next-step facility (TMNS) in which physics issues will not be at issue. TMNS will be a facility for engineering research and development. The end cells of TMNS are expected to be appropriate for a tandem-mirror demonstration fusion reactor (TMR), construction of which should begin about 1986 for operation in the 1990's.

Van Atta, C.M.

1981-03-12

96

Electron-Cyclotron Resonance Heating in Tandem Mirrors  

Microsoft Academic Search

Using numerical ray-tracing techniques, we study the propagation and absorption profiles of electromagnetic waves launched in the end cells of three different tandem mirrots: Phaedrus, an overdense low-temperature tandem mirror with plugs; TASKA, a conceptual tandem mirror with plugs and thermal barrier; and TMX-U, a tandem mirror with a significant hot-electron population. In particular, the effects of weakly relativistic thermal

N. T. Lam; J. E. Scharer; K. R. Audenaerde

1985-01-01

97

Tandem repeats finder: a program to analyze DNA sequences  

Microsoft Academic Search

A tandem repeat in DNA is two or more contiguous, approximate copies of a pattern of nucleotides. Tandem repeats have been shown to cause human disease, may play a variety of regulatory and evolutionary roles and are important laboratory and analytic tools. Extensive knowledge about pattern size, copy number, mutational history, etc. for tandem repeats has been limited by the

Gary Benson

1999-01-01

98

Evolution of Tandemly Arrayed Genes in Multiple Species  

Microsoft Academic Search

Tandemly arrayed genes (TAG) constitute a large fraction of most genomes and play impor- tant biological roles. They evolve through unequal recombination, which places duplicated genes next to the original ones (tandem duplications). Many algorithms have been proposed to infer a tandem duplication history for a TAGs cluster in a single species. However, the presence of dieren t tran- scriptional

Mathieu Lajoie; Denis Bertrand; Nadia El-mabrouk

2007-01-01

99

Tandem mass spectrometry in the clinical chemistry laboratory  

Microsoft Academic Search

Tandem mass spectrometry is becoming an increasingly important analytical technology in the clinical laboratory environment. Applications in toxicology and therapeutic drug monitoring have opened the door for tandem mass spectrometry and now we are seeing a vast array of new applications being developed. It has been the combination of tandem mass spectrometry with sample introduction techniques employing atomospheric pressure ionization

Kent C. Dooley

2003-01-01

100

A Survey On Algorithmic Aspects Of Tandem Repeats Evolution  

Microsoft Academic Search

Local repetitions in genomes are called tandem repeats. A tandem repeat contains multiple, but slightly dieren t copies of a repeated unit. It changes over time as the copies are altered by mutations, when additional copies are created by amplic ation of an existing copy, or when a copy is removed by contraction. Theses changes let tandem repeats evolve dynamically.

Eric Rivals

2004-01-01

101

Terminal lens for an FN tandem  

SciTech Connect

An electrostatic quadrupole triplet (ELQT) will be installed in the terminal of the Argonne FN tandem accelerator. The lens will be used in conjunction with foil stripping to maximize the transmission of heavy ions through the high-energy accelerator tube. The lens has steering capability and is controlled by a microcomputer located in the terminal.

Den Hartog, P.K.; Munson, F.H.; Heath, C.E.

1982-01-01

102

Short tandem repeat polymorphism evolution in humans  

Microsoft Academic Search

Forty-five dinucleotide short tandem repeat polymorphisms were typed in ten large samples of a globally distributed set of populations. Although these markers had been selected for high heterozygosity in European populations, we found them to be sufficiently informative for linkage analysis in non-Europeans. Heterozygosity, mean number of alleles, and mean number of private alleles followed a common trend: they were

F Calafell; A Shuster; WC Speed; JR Kidd; KK Kidd

1998-01-01

103

Parametric Studies of Tandem Mirror Reactors.  

National Technical Information Service (NTIS)

To increase net power plant efficiency and reduce the recirculating power fraction, a tandem mirror reactor should have Q approx. 10. With this in mind, we solve a set of space and time independent power balance equations including quasi-neutrality requir...

K. C. Shaing R. W. Conn J. Kesner

1978-01-01

104

Designs of tandem-mirror fusion reactors  

NASA Astrophysics Data System (ADS)

A comparative evaluation of several end plug configurations for tandem mirror fusion reactors with thermal barriers were completed. The axi-cell configuration was selected for further study. The axi-cell end plug has a simple mirror cell produced by two circular coils followed by a transition coil and a yin-yang pair, which provides for MHD stability.

Carlson, G. A.; Barr, W. L.; Boghosian, B. M.; Devoto, R. S.; Doggett, J. N.; Hamilton, G. W.; Johnston, B. M.; Lee, J. D.; Logan, B. G.; Moir, R. W.

1981-10-01

105

25 MV Tandem Accelerator at Oak Ridge.  

National Technical Information Service (NTIS)

A new heavy-ion accelerator facility is under construction at the Oak Ridge National Laboratory. A brief description of the scope and status of this project is presented with emphasis on the first operational experience with the 25 MV tandem accelerator. ...

C. M. Jones

1980-01-01

106

Rigid ballooning modes in tandem mirrors  

Microsoft Academic Search

Stability of tandem mirrors to rigid-displacement ballooning modes is studied using vacuum field geometry. Results show substantial improvement in values of beta over those predicted by ‘‘infinite-m’’ theory. Previous work has shown that kinetic effects stabilize these latter short-wavelength modes, suggesting that only the rigid mode survives.

Thomas B. Kaiser; William McCay Nevins; L. Donald Pearlstein

1983-01-01

107

Rigid ballooning modes in tandem mirrors  

Microsoft Academic Search

Stability of tandem mirrors to rigid-displacement ballooning modes is studied using vacuum field geometry. Results show substantial improvement in values of beta over those predicted by ''infinite-m'' theory. Previous work has shown that kinetic effects stabilize these latter short-wavelength modes, suggesting that only the rigid mode survives.

Thomas B. Kaiser; William McCay Nevins; L. Donald Pearlstein

1983-01-01

108

Technology for large tandem mirror experiments  

SciTech Connect

Construction of a large tandem mirror (MFTF-B) will soon begin at Lawrence Livermore National Laboratory (LLNL). Designed to reach break-even plasma conditions, the facility will significantly advance the physics and technology of magnetic-mirror-based fusion reactors. This paper describes the objectives and the design of the facility.

Thomassen, K.I.

1980-09-04

109

Edge diagnostics for tandem mirror machines  

SciTech Connect

The edge plasma in a tandem mirror machine shields the plasma core from cold neutral gas and impurities. A variety of diagnostics are used to measure the fueling, shielding, and confinement of the edge plasma in both the end plug and central cell regions. Fast ion gauges and residual gas analyzers measure the gas pressure and composition outside of the plasma. An array of Langmuir probes is used to measure the electron density and temperature. Extreme ultraviolet (euv) and visible spectroscopy are used to measure both the impurity and deuterium densities and to estimate the shielding factor for the core plasma. The linear geometry of a tandem mirror also allows direct measurements of the edge plasma by sampling the ions and electrons lost but the ends of the machine. Representative data obtained by these diagnostics during operation of the Tandem Mirror Experiment (TMX) and Tandem Mirror Experiment-Upgrade (TMX-U) experiments are presented. Diagnostics that are currently being developed to diagnose the edge plasma are also discussed.

Allen, S.L.

1984-09-14

110

Tandem Teaching Relieves Boredom, Maximizes Class Time.  

ERIC Educational Resources Information Center

|Tandem teaching employs the best qualities of seven innovative classroom approaches (team teaching, core curriculum, flexible scheduling, elective classes, individualized instruction, peer tutoring, and computer-assisted instruction) to restructure the curriculum, relieve boredom, and maximize class time. Success depends on careful planning and…

Bergman, Floyd L.

1990-01-01

111

Broadband supercontinuum generation in a single potassium di-hydrogen phosphate (KDP) crystal achieved in tandem with sum frequency generation  

Microsoft Academic Search

We present here an enhanced broadband supercontinuum generation in a potassium di-hydrogen phosphate (KDP) crystal. The enhancement\\u000a in the bandwidth of the white light is obtained towards the shorter wavelength regime (<400 nm) by employing supercontinuum\\u000a generation and sum frequency generation in tandem. The tunability in the blue region of the spectrum with angle is demonstrated.\\u000a The bandwidth of supercontinuum achieved

R. Sai Santosh Kumar; S. Sree Harsha; D. Narayana Rao

2007-01-01

112

Locomotion by Tandem and Parallel Wings  

NASA Astrophysics Data System (ADS)

A two-dimensional analysis was carried out on the locomotion by tandem and parallel wings in relation to the free flight of dragonflies and beetles, remarking the mutual interference between fore and hind wings. The results obtained are summarized as follows: In the case of tandem wings, (1)High thrust and propulsive efficiency can be achieved when the forewing oscillates with a definite phase lag behind the hindwing, as in the case of real dragonflies, (2)Somewhat smaller amplitude of hindwing leads to optimum condition for work sharing of two wings, (3)The hard forewing does not serve for the thrust and propulsive efficiency, whereas the hard hindwing does for the augmentation of them; In the case of parallel wings, (4)The hard wing placed near the soft wing acts nearly as an infinite plate, as for the ground effect, increasing both thrust and propulsive efficiency.

Tanida, Yoshimichi

113

Nucleic Acid Recognition by Tandem Helical Repeats  

PubMed Central

Protein domains constructed from tandem ?-helical repeats have until recently been primarily associated with protein scaffolds or RNA recognition. Recent crystal structures of human mitochondrial termination factor MTERF1 and Bacillus cereus alkylpurine DNA glycosylase AlkD bound to DNA revealed two new superhelical tandem repeat architectures capable of wrapping around the double helix in unique ways. Unlike DNA sequence recognition motifs that rely mainly on major groove read-out, MTERF and ALK motifs locate target sequences and aberrant nucleotides within DNA by resculpting the double-helix through extensive backbone contacts. Comparisons between MTERF and ALK repeats, together with recent advances in ssRNA recognition by Pumilio/FBF (PUF) domains, provide new insights into the fundamental principles of protein-nucleic acid recognition.

Rubinson, Emily H.; Eichman, Brandt F.

2013-01-01

114

Improved mass accuracy for tandem mass spectrometry  

Microsoft Academic Search

With the emergence of top-down proteomics, the ability to achieve high mass measurement accuracy on tandem MS\\/MS data will\\u000a be beneficial for protein identification and characterization. (FT-ICR) Fourier transform ion cyclotron resonance mass spectrometers\\u000a are the ideal instruments to perform these experiments with their ability to provide high resolution and mass accuracy. A\\u000a major limitation to mass measurement accuracy in

Nathan K. Kaiser; Gordon A. Anderson; James E. Bruce

2005-01-01

115

DDES and IDDES of tandem cylinders.  

SciTech Connect

The paper presents an overview of the authors contribution to the BANC-I Workshop on the flow past tandem cylinders (Category 2). It includes an outline of the simulation approaches, numerics, and grid used, the major results of the simulations, their comparison with available experimental data, and some preliminary conclusions. The effect of varying the spanwise period in the simulations is strong for some quantities, and not others.

Balakrishnan, R.; Garbaruk, A.; Shur, M.; Strelets, M.; Spalart, P.; New Technologies and Services - Russia; St.-Peterburg State Polytechnic Univ.; Boeing Commercial Airplanes

2010-09-09

116

A tandem clustering process for multimodal datasets  

Microsoft Academic Search

Clustering multimodal datasets can be problematic when a conventional algorithm such as k-means is applied due to its implicit assumption of Gaussian distribution of the dataset. This paper proposes a tandem clustering process for multimodal data sets. The proposed method first divides the multimodal dataset into many small pre-clusters by applying k-means or fuzzy k-means algorithm. These pre-clusters are then

Catherine Cho; Sooyoung Kim; Jaewook Lee; Dae-won Lee

2006-01-01

117

ORNL 25 MV tandem accelerator control system  

SciTech Connect

The CAMAC-based control system for the 25 MV tandem electrostatic accelerator of the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory (ORNL) was specified by ORNL and built by the National Electrostatics Corporation. Two Perkin-Elmer 32-bit minicomputers are used in the system, a message switching computer and a supervisory computer. The message switching computer transmits and receives control information on six serial highways. This computer shares memory with the supervisory computer. Operator consoles are located on a serial highway; control is by means of a console CRT, trackball, and assignable shaft encoders and meters. Two identical consoles operate simultaneously: one is located in the tandem control room; the other is located in the cyclotron control room to facilitate operation during injection of tandem beams into the cyclotron or when beam lines under control of the cyclotron control system are used. The supervisory computer is used for accelerator parameter setup calculations, actual accelerator setup for new beams based on scaled, recorded parameters from previously run beams, and various other functions. Nearly seven years of control system operation and improvements will be discussed.

Juras, R.C.; Biggerstaff, J.A.; Hoglund, D.E.

1985-01-01

118

The metal interlayer in the charge generation layer of tandem organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

This work studies the interface in the charge generation layer (CGL), consisting of aluminum (Al) doped in poly(ethylene glycol) dimethyl ether as an n-type layer and 2, 3, 5, 6-tetrafluoro-7, 7, 8, 8-tetracyanoquinodimethane (F4-TCNQ) doped in N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine as an p-type layer, in tandem organic light-emitting diodes (OLEDs). Introducing a thin high work function metal interlayer (e.g., Ag or Au) effectively improves the transport and inhibits the accumulation of charges in the CGL, which markedly reduces the operating voltage and enhances the efficiency of tandem OLEDs. We attribute that the high density of surface states on metal clusters (interlayer) reduce the junction barrier to facilitate the transport of carriers through CGL. Experimental results show enhancements of tandem OLEDs by an additional metal interlayer as follows: luminous efficiency increases from 37.2 to 51.4 cd A-1, the light turn-on voltage decreases from 9.2 to 6.6 V, and luminescence at 10 mA cm-2 increases from 3712 to 5211 cd m-2.

Lee, Yu-Hao; Lin, Ming-Wei; Wen, Ten-Chin; Guo, Tzung-Fang

2013-10-01

119

Tandem Computers, Inc. Tandem Nonstop II COBOL T9201E01.  

National Technical Information Service (NTIS)

This Validation Summary Report (VSR) for the Tandem Computers, Inc., COBOL T9201E01 running under the Guardian T9050A05 provides a consolidated summary of the results obtained from the validation of the subject compiler against the 1974 COBOL Standard (X3...

1983-01-01

120

HRIBF Tandem Accelerator Radiation Safety System Upgrade  

SciTech Connect

The HRIBF Tandem Accelerator Radiation Safety System was designed to permit experimenters and operations staff controlled access to beam transport and experiment areas with accelerated beam present. Neutron-Gamma detectors are mounted in eaeh area at points of maximum dose rate and the resulting signals are integrated by redundan~ circuitry; beam is stopped if dose rate or integrated dose exceeds established limits. This paper will describe the system, in use for several vears at the HRIBF, and discuss changes recently made to modernize the system and to make the system compliant with DOE Order 5480.25 and related ORNL updated safety rules.

Blankenship, J.L.; Juras, R.C.

1998-11-04

121

Profiling short tandem repeats from short reads.  

PubMed

Short tandem repeats (STRs), also known as microsatellites, have a wide range of applications, including medical genetics, forensics, and population genetics. High-throughput sequencing has the potential to profile large numbers of STRs, but cumbersome gapped alignment and STR-specific noise patterns hamper this task. We recently developed an algorithm, called lobSTR, to overcome these challenges and to accurately profile STRs from short reads. Here we describe how to use lobSTR to call STR variations from high-throughput sequencing datasets and to diagnose the quality of the calls. PMID:23872972

Gymrek, Melissa; Erlich, Yaniv

2013-01-01

122

Enhanced Shock Wave-Assisted Transformation of Escherichia coli  

Microsoft Academic Search

The objective of the study was to demonstrate that shock wave-induced transfer of DNA into bacteria can be increased by enhancing cavitation using dual-pulse (tandem) shock waves. Escherichia coli and plasmid were transferred to test vials. Competent cells were prepared at different concentrations of CaCl2. Single pulses and tandem shock waves were compared as were three treatment temperatures: 0, 10

Achim M. Loske; Juan Campos-Guillen; Francisco Fernández; Eduardo Castaño-Tostado

2011-01-01

123

Monitoring Bilingualism: Pedagogical Implications of the Bilingual Tandem Analyser  

ERIC Educational Resources Information Center

|Tandem learning is the collaborative learning partnership of two language learners with complementary language combinations, for example an Irish student learning German and a German student learning English. One of the major principles in tandem learning, apart from reciprocity and learner autonomy, is balanced bilingualism. While learners may…

Schwienhorst, Klaus; Borgia, Alexandre

2006-01-01

124

Simple tandem DNA repeats and human genetic disease  

Microsoft Academic Search

The human genome contains many repeated DNA sequences that vary in complexity of repeating unit from a single nucleotide to a whole gene. The repeat sequences can be widely dispersed or in simple tandem arrays. Arrays of up to 5 or 6 nt are known as simple tandem repeats, and these are widely dispersed and highly polymorphic. Members of one

G. R. Sutherland; R. I. Richards

1995-01-01

125

Summary of the tandem energy focusing explosive warhead technologies  

SciTech Connect

In this paper, on the basis of a great amount of the analysis of the tandem energy focusing explosive warhead in our country and other countries, we summarize the design demand of the tandem warhead, the delayed ignition controlling technique between the explosives, the isolating explosion protection technique and the detonator technique.

Zhou, T.S.

1996-09-26

126

V/STOL Tandem Fan Transition Section Model Test.  

National Technical Information Service (NTIS)

An approximately 0.25 scale model of the transition section of a tandem fan variable cycle engine nacelle was tested in the NASA Lewis Research Center 10-by-10 foot wind tunnel. Two 12-inch, tip-turbine driven fans were used to simulate a tandem fan engin...

W. E. Simpkin

1982-01-01

127

Incomplete Incorporation of Tandem Subunits in Recombinant Neuronal Nicotinic Receptors  

Microsoft Academic Search

Tandem constructs are increasingly being used to restrict the composition of recombinant multi- meric channels. It is therefore important to assess not only whether such approaches give functional channels, but also whether such channels completely incorporate the subunit tandems. We have addressed this question for neuronal nicotinic acetylcholine receptors, using a channel mutation as a reporter for subunit incorporation. We

Paul J. Groot-Kormelink; Steven D. Broadbent; James P. Boorman; Lucia G. Sivilotti

2004-01-01

128

Tandem mass spectrometry for sequencing proanthocyanidins.  

PubMed

Proanthocyanidins (PAs) are a group of bioflavonoids consisting of oligomers based on catechin monomeric units. These polyphenolic compounds are widely distributed in higher plants and are an integral part of the human diet. A sensitive LC-tandem mass spectrometric (LC/ESI-MS(n)) method in the positive ion mode for sequencing these ubiquitous and highly beneficial antioxidants is described. The hydroxylation patterns and interflavanoid linkage for A- and B-type PAs were determined by fragment ions derived from a retro-Diels-Alder (RDA) fission, heterocyclic ring fission (HRF), a novel benzofuran-forming (BFF) fission described here for the first time, and a quinone methide (QM) fission. The subunit sequence of the PAs was determined by diagnostic ions derived from HRF/RDA fission, HRF/BFF fission, and RDA/HRF fission together with QM fission. A total of 26 PAs were reliably sequenced by the newly established tandem mass spectrometric protocol. It is shown that the protocol based on a combination of these different fragmentation patterns allows for uniquely identifying PA oligomers. PMID:17297981

Li, Hui-Jing; Deinzer, Max L

2007-02-15

129

Improved Mass Accuracy for Tandem Mass Spectrometry  

SciTech Connect

With the emergence of top-down proteomics, the ability to achieve high mass measurement accuracy on tandem MS/MS data will be beneficial for protein identification and characterization. (FT-ICR) Fourier transform ion cyclotron resonance mass spectrometers are the ideal instruments to perform these experiments with their ability to provide high resolution and mass accuracy. A major limitation to mass measurement accuracy in FT-ICR instruments arises from the occurrence of space charge effects. These space charge effects shift the cyclotron frequency of the ions, which compromises the mass measurement accuracy. While several methods have been developed that correct these space charge effects, they have limitations when applied to MS/MS experiments. It has already been shown that additional information inherent in electrospray spectra can be used for improved mass measurement accuracy with the use of a computer algorithm called DeCAL (deconvolution of Coulombic affected linearity). This paper highlights a new application of the strategy for improved mass accuracy in tandem mass analysis. The results show a significant improvement in mass measurement accuracy on complex electron capture dissociation spectra of proteins. We also demonstrate how the improvement in mass accuracy can increase the confidence in protein identification from the fragment masses of proteins acquired in MS/MS experiments.

Kaiser, Nathan K.; Anderson, Gordon A.; Bruce, James E.

2005-04-01

130

High efficiency tandem organic light-emitting devices with Al/WO3/Au interconnecting layer  

NASA Astrophysics Data System (ADS)

An interconnecting layer of Al (2 nm)/WO3 (3 nm)/Au (16 nm) was studied for application in tandem organic light-emitting devices. It can be seen that the Al/WO3/Au structure plays the role of an excellent interconnecting layer. The introduction of WO3 in the connection unit significantly improves the device efficiency as compared to the case of Al/Au. Thus, the current efficiency of the two-unit tandem devices is enhanced by two factors with respect to the one-unit devices. The green two-unit tandem device of indium tin oxide/MoO3/4,4'-N,N'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl(NPB)/tris(8-hydroxylquinoline) aluminum (Alq3):10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one (C545T)/Alq3/LiF/Al/WO3/Au/MoO3/NPB/Alq3:C545T/Alq3/LiF/Al showed a maximum current efficiency of 33.9 cd/A and a power efficiency of 12.0 lm/W.

Zhang, Hongmei; Dai, Yanfeng; Ma, Dongge; Zhang, Hongmei

2007-09-01

131

Inverted Polymeric Photovoltaic Cells and Parallel Tandems with Transparent Single Wall Carbon Nanotubes Interlayer  

NASA Astrophysics Data System (ADS)

We demonstrate an organic photovoltaic (OPV) monolithic multi junction cell in a parallel electrical configuration utilizing polymers with complementary absorption spectra and transparent single wall CNT (SWCNT) as an interlayer electrode (IE). Parallel tandem cells are of importance because they can append to the limited spectral coverage of available polymers and because there is no need balance current as is the case with in-series configurations. Devices comprise of polymeric sub cells where one is inverted using ZnO nanoparticles and a MoO3 buffer layers, this inverted structure allows for the SWCNT IE to function as a cathode. Each sub cell is characterized independently and the short circuit current of the tandem device is shown to increase. Overall increase in efficiency is observed and attributed to enhanced spectral coverage by spectrally complimentary polymers and the effective use of parallel tandem architecture. We also demonstrate a semi transparent inverted OPV structure with a SWCNT electrode and a efficiency of over 3%.

Mielczarek, Kamil; Cook, Alex; Zakhidov, Anvar; Kaskela, Antti; Nasibulin, Albert; Kauppinen, Esko

2011-03-01

132

Electronic Tandem Language Learning (eTandem): A Third Approach to Second Language Learning for the 21st Century  

ERIC Educational Resources Information Center

Tandem language learning occurs when two learners of different native languages work together to help each other learn the other language. First used in face-to-face contexts, Tandem is now increasingly being used by language-learning partners located in different countries who are linked via various forms of electronic communication, a context…

Cziko, Gary A.

2004-01-01

133

Electronic Tandem Language Learning (eTandem): A Third Approach to Second Language Learning for the 21st Century  

ERIC Educational Resources Information Center

|Tandem language learning occurs when two learners of different native languages work together to help each other learn the other language. First used in face-to-face contexts, Tandem is now increasingly being used by language-learning partners located in different countries who are linked via various forms of electronic communication, a context…

Cziko, Gary A.

2004-01-01

134

Hierarchical nanoparticle bragg mirrors: tandem and gradient architectures.  

PubMed

To manipulate electrons in semiconductor electronic and optical devices, the usual approach is through materials composition, electronic bandgap, doping, and interface engineering. More advanced strategies for handling electrons in semiconductor devices include composition-controlled heterostructures and gradient structures. By analogy to the manipulation of electrons in semiconductor crystals by electronic bandgaps, photons in photonic crystals can be managed using photonic bandgaps. In this context, the simplest photonic crystal is the Bragg mirror, a periodic dielectric construct whose photonic bandgap is engineered through variations of the optical thickness of its constituent layers. Traditionally the materials comprising these periodic dielectric layers are nonporous, and they have mainly been used in the field of optical and photonic devices. More recently these Bragg mirrors have been made porous by building the layers from nanoparticles with functionality and utility that exploit their internal voids. These structures are emerging in the area of photonic color-coded chemical sensing and controlled chemical release. Herein, a strategy for enhancing the functionality and potential utility of nanoparticle Bragg mirrors by making the constituent dielectric layers aperiodic and porous is described. It is exemplified by prototypical tandem and gradient structures that are fully characterized with regards to their structure, porosity, and optical and photonic properties. PMID:22009683

Redel, Engelbert; Huai, Chen; Renner, Michael; von Freymann, Georg; Ozin, Geoffrey A

2011-10-19

135

Discrete elements within the SV40 enhancer region display different cell-specific enhancer activities.  

PubMed Central

The SV40 enhancer contains three genetically defined elements, called A, B and C, that can functionally compensate for one another. By using short, synthetic DNA oligonucleotides, we show that each of these elements can act autonomously as an enhancer when present as multiple tandem copies. Analysis of a progressive series of B element oligomers shows a single element is ineffective as an enhancer and that the activity of two or more elements increases with copy number. Assay in five different cell lines of two separate enhancers containing six tandem copies of either the B or C element shows that these elements possess different cell-specific activities. Parallel oligomer enhancer constructs containing closely spaced double point mutations display no enhancer activity in any of the cell lines tested, indicating that these elements represent single units of enhancer function. These elements contain either a 'core' or 'octamer' consensus sequence but these consensus sequences alone are not sufficient for enhancer activity. The different cell-specific activities of the B and C elements are consistent with functional interactions with different trans-acting factors. We discuss how tandem duplication of such dissimilar elements, as in the wild-type SV40 72-bp repeats, can serve to expand the conditions under which an enhancer can function. Images Fig. 2. Fig. 3. Fig. 4.

Ondek, B; Shepard, A; Herr, W

1987-01-01

136

The impact of intermediate reflectors on light absorption in tandem solar cells with randomly textured surfaces  

NASA Astrophysics Data System (ADS)

The impact of dielectric intermediate reflectors on the light absorption in the top cell of an a-Si:H/?c-Si:H tandem solar cell comprising randomly textured surfaces was investigated by rigorous diffraction theory. Despite the strong light scattering, we found Fabry-Pérot oscillations for the absorption with a decreasing modulation for an increasing thickness of the intermediate layer, a larger oscillation period when compared to thin films and a homogenization of the absorption profile. Optimized intermediate reflectors generate an absorption enhancement in the a-Si:H film, which varies between a factor of 2 and more than 3 for wavelengths of strong and weak absorption, respectively.

Rockstuhl, C.; Lederer, F.; Bittkau, K.; Beckers, T.; Carius, R.

2009-05-01

137

Oligomeric Structure of the MALT1 Tandem Ig-Like Domains  

PubMed Central

Background Mucosa-associated lymphoid tissue 1 (MALT1) plays an important role in the adaptive immune program. During TCR- or BCR-induced NF-?B activation, MALT1 serves to mediate the activation of the IKK (I?B kinase) complex, which subsequently regulates the activation of NF-?B. Aggregation of MALT1 is important for E3 ligase activation and NF-?B signaling. Principal Findings Unlike the isolated CARD or paracaspase domains, which behave as monomers, the tandem Ig-like domains of MALT1 exists as a mixture of dimer and tetramer in solution. High-resolution structures reveals a protein-protein interface that is stabilized by a buried surface area of 1256 Å2 and contains numerous hydrogen and salt bonds. In conjunction with a second interface, these interactions may represent the basis of MALT1 oligomerization. Conclusions The crystal structure of the tandem Ig-like domains reveals the oligomerization potential of MALT1 and a potential intermediate in the activation of the adaptive inflammatory pathway. Enhanced version This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1.

Qiu, Liyan; Dhe-Paganon, Sirano

2011-01-01

138

Development of a liquid chromatography tandem mass spectrometry method for simultaneous determination of eight adulterants in slimming functional foods  

Microsoft Academic Search

A method for simultaneous determination of eight adulterants including two appetite suppressants, two energy expenditure-enhancing drugs, one diuretic and three cathartics in slimming functional foods by high performance liquid chromatography with electrospray ionization–tandem mass spectrometry (HPLC-ESI–MS\\/MS) was established. After samples were ultrasonically extracted with 70% (v\\/v) methanol aqueous solution and centrifuged, the components of ephedrine, norpseudoephedrine, fenfluramine, sibutramine, clopamide, emodin,

Ying Shi; Chengjun Sun; Bo Gao; Aimin Sun

2011-01-01

139

Negative deuterium ions for tandem mirror next step and tandem mirror reactors  

SciTech Connect

Recent designs for mirror fusion reactors with good power balance include ambipolar potential plugs to reduce end losses and thermal barriers to maintain a difference in electron temperature between the large-volume central cell plasma and the confining end plugs. These designs led to several new requirements for D/sup 0/ neutral beams derived from negative ions at energies of 150 to 200 keV and possibly higher. Such beams are required for injection of fat ions into the plugs and the barrier and for charge-exchange pumping of thermal ions diffusing into the barrier. Negative ions are preferred for these purposes because of their relatively high efficiency of neutralization and their high purity of single-energy D/sup -/. Examples of injector designs for Tandem Mirror Next Step (TMNS) and Tandem Mirror Reactors (TMR) are presented.

Hamilton, G.W.

1980-09-25

140

Routine approach to qualitatively screen for 300 pesticides and quantify those frequently detected in fruits and vegetables using liquid chromatography tandem mass spectrometry  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper describes an efficient and effective analytical scheme to first screen for 300 pesticides in fruit and vegetables samples using liquid chromatography tandem mass spectrometry (LC-MS/MS) with a commercial enhanced product ion method. Then, the presumed positive extracts were analyzed using...

141

TMX-U (Tandem Mirror Experiment-Upgrade) tandem-mirror thermal-barrier experiments  

SciTech Connect

Thermal-barrier experiments have been carried out in the Tandem Mirror Experiment-Upgrade (TMX-U). Measurements of nonambipolar and ambipolar radial transport show that these transport processes, as well as end losses, can be controlled at modest densities and durations. Central-cell heating methods using ion-cyclotron heating (ICH) and neutral-beam injection have been demonstrated. Potential mesurements with recently developed methods indicate that deep thermal barriers can be established.

Simonen, T.C.; Allen, S.L.; Baldwin, D.E.; Barter, J.D.; Berzins, L.V.; Carter, M.R.; Casper, T.A.; Clauser, J.F.; Coensgen, F.H.; Correll, D.L.

1986-10-29

142

Organic ion imaging using tandem mass spectrometry  

SciTech Connect

A triple-quadrupole mass spectrometer has been interfaced with a wide-angle secondary ion microprobe. The combination permits acquisition of data necessary to determine the distribution of targeted organic analytes even in the presence of overwhelming isobaric interference. Micrographs generated from secondary ion intensity alone are compared to those generated using secondary ionization with tandem mass spectrometry (MS/MS), both for image reference and to show the improvement in image quality that can be attained when MS/MS is employed. Inhomogeneous mixtures of glycerol, KCl, and asparagine on 1-cm-diameter aluminum targets were used to demonstrate the instrument`s selectivity. Secondary ions generated from samples of this system include isobaric {sup 133}Cs{sup +} implanted from the primary ion beam, the {sup 41}K{sup +} -glycerol adduct, and protonated asparagine. 30 refs., 9 figs., 1 tab.

Todd, P.J.; Short, R.T.; Grimm, C.C.; Holland, W.M. [Oak Ridge National Lab., TN (United States)] [and others

1992-09-01

143

Clustering Millions of Tandem Mass Spectra  

PubMed Central

Summary Tandem mass spectrometry (MS/MS) experiments often generate redundant datasets containing multiple spectra of the same peptides. Clustering of MS/MS spectra takes advantage of this redundancy by identifying multiple spectra of the same peptide and replacing them with a single representative spectrum. Analyzing only representative spectra results in significant speed-up of MS/MS database searches. We present an efficient clustering approach for analyzing large MS/MS datasets (over ten million spectra) with a capability to reduce the number of spectra submitted to further analysis by an order of magnitude. The MS/MS database search of clustered spectra results in fewer spurious hits to the database and increases number of peptide identifications as compared to regular non-clustered searches. Our open source software MS-Clustering is available for download at http://peptide.ucsd.edu or can be run online at http://proteomics.bioprojects.org/MassSpec.

Frank, Ari M.; Bandeira, Nuno; Shen, Zhouxin; Tanner, Stephen; Briggs, Steven P.; Smith, Richard D.; Pevzner, Pavel A.

2008-01-01

144

Engineering problems of tandem-mirror reactors  

NASA Astrophysics Data System (ADS)

A comparative evaluation of several end plug configurations for tandem mirror fusion reactors with thermal barriers is presented. The axi-cell configuration was selected for further study and will be the basis for a detailed conceptual design study to be carried out over the next two years. The axi-cell end plug has a simple mirror cell produce by two circular coils followed by a transition coil and a yin-yang pair, which provides for MHD stability. Scientific and technological understanding and innovation are needed in the area of thermal barrier pumping - a process by which unwanted particles are removed (pumped) from certain regions of velocity and real space in the end plug. Removal of exhaust fuel ions, fusion ash and impurities by action of a halo plasma and plasma dump in the mirror end region is another challenging engineering problem discussed.

Moir, R. W.; Barr, W. L.; Boghosian, B. M.; Carlson, G. A.; Devoto, R. S.; Doggett, J. N.; Hamilton, G. W.; Johnson, B. M.; Kumai, W. N.; Lee, J. D.

1981-10-01

145

Protein Sequencing with Tandem Mass Spectrometry  

NASA Astrophysics Data System (ADS)

The recent introduction of electrospray ionization techniques that are suitable for peptides and whole proteins has allowed for the design of mass spectrometric protocols that provide accurate sequence information for proteins. The advantages gained by these approaches over traditional Edman Degradation sequencing include faster analysis and femtomole, sometimes attomole, sensitivity. The ability to efficiently identify proteins has allowed investigators to conduct studies on their differential expression or modification in response to various treatments or disease states. In this chapter, we discuss the use of electrospray tandem mass spectrometry, a technique whereby protein-derived peptides are subjected to fragmentation in the gas phase, revealing sequence information for the protein. This powerful technique has been instrumental for the study of proteins and markers associated with various disorders, including heart disease, cancer, and cystic fibrosis. We use the study of protein expression in cystic fibrosis as an example.

Ziady, Assem G.; Kinter, Michael

146

Temporally regulated tandem promoters in Micromonospora echinospora.  

PubMed Central

A collection of promoters from the Micromonospora echinospora strain that produces the calichemicin antitumor antibiotics was identified by the use of the promoter-probe vector pIJ486 in Streptomyces lividans. A 0.4-kilobase-pair Micromonospora DNA fragment was found to contain multiple tandem promoters which were characterized by S1 nuclease protection, Northern blotting, and DNA sequence determination. Analysis of RNA isolated from timed Micromonospora cultures revealed two classes of promoters within the 0.4-kilobase-pair fragment. The P2 promoter was maximally active during the exponential phase. In contrast, the P1 promoter cluster, consisting of three closely spaced start sites located 80 base pairs upstream of P2, was maximally active during the stationary phase. Because P1 was strongly induced in synchrony with calichemicin drug production, P1 is of potential utility in expressing cloned genes specifically during the stationary phase. Images

Baum, E Z; Love, S F; Rothstein, D M

1988-01-01

147

Coevolution of retroelements and tandem zinc finger genes  

PubMed Central

Vertebrate genomes encode large and highly variable numbers of tandem C2H2 zinc finger (tandem ZF) transcription factor proteins. In mammals, most tandem ZF genes also encode a KRAB domain (KZNF proteins). Very little is known about what forces have driven the number and diversity of tandem ZF genes. Recent studies suggest that one role of KZNF proteins is to bind and repress transcription of exogenous retroviruses and their endogenous counterpart LTR retroelements. We report a striking correlation across vertebrate genomes between the number of LTR retroelements and the number of host tandem ZF genes. This correlation is specific to LTR retroelements and ZF genes and was not explained by covariation in other genomic features. We further show that recently active LTR retroelements are correlated with recent tandem ZF gene duplicates across vertebrates. On branches of the primate phylogeny, we find that the appearance of new families of endogenous retroviruses is strongly predictive of the appearance of new duplicate KZNF genes. We hypothesize that retroviral and LTR retroelement burden drives evolution of host tandem ZF genes. This hypothesis is consistent with previously described molecular evolutionary patterns in duplicate ZF genes throughout vertebrates. To further explore these patterns, we investigated 34 duplicate human KZNF gene pairs, all of which underwent an early burst of divergence in the major nucleotide contact residues of their ZF domains, followed by purifying selection in both duplicates. Our results support a host-pathogen model for tandem ZF gene evolution, in which new LTR retroelement challenges drive duplication and divergence of host tandem ZF genes.

Thomas, James H.; Schneider, Sean

2011-01-01

148

Recent Activities in Tandem, Booster and TRIAC at Tokai  

SciTech Connect

Present status and recent developments of the tandem accelerator, superconducting booster, and radioactive nuclear beam accelerator TRIAC are presented. The terminal voltage of the tandem accelerator reached 19.1 MV by replacing acceleration tubes. The multi-charged positive-ion injector was installed in the terminal of the tandem accelerator, supplying noble-gas ions. A superconducting cavity for low-velocity ions was developed. Radioactive nuclear beams of {sup 8}Li, {sup 123}In, and {sup 143}Ba were accelerated. Recent experimental results of nuclear physics are also reported.

Ishii, Tetsuro; Matsuda, Makoto; Kabumoto, Hiroshi; Osa, Akihiko [Department of Research Reactor and Tandem Accelerator, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan)

2009-05-04

149

Recent Activities in Tandem, Booster and TRIAC at Tokai  

NASA Astrophysics Data System (ADS)

Present status and recent developments of the tandem accelerator, superconducting booster, and radioactive nuclear beam accelerator TRIAC are presented. The terminal voltage of the tandem accelerator reached 19.1 MV by replacing acceleration tubes. The multi-charged positive-ion injector was installed in the terminal of the tandem accelerator, supplying noble-gas ions. A superconducting cavity for low-velocity ions was developed. Radioactive nuclear beams of 8Li, 123In, and 143Ba were accelerated. Recent experimental results of nuclear physics are also reported.

Ishii, Tetsuro; Matsuda, Makoto; Kabumoto, Hiroshi; Osa, Akihiko

2009-05-01

150

14 CFR 105.45 - Use of tandem parachute systems.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Use of tandem parachute systems. 105.45 Section 105.45 Aeronautics... AIR TRAFFIC AND GENERAL OPERATING RULES PARACHUTE OPERATIONS Parachute Equipment and Packing § 105.45 Use of...

2013-01-01

151

14 CFR 105.45 - Use of tandem parachute systems.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Use of tandem parachute systems. 105.45 Section 105.45 Aeronautics... AIR TRAFFIC AND GENERAL OPERATING RULES PARACHUTE OPERATIONS Parachute Equipment and Packing § 105.45 Use of...

2009-01-01

152

14 CFR 105.45 - Use of tandem parachute systems.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Use of tandem parachute systems. 105.45 Section 105.45 Aeronautics... AIR TRAFFIC AND GENERAL OPERATING RULES PARACHUTE OPERATIONS Parachute Equipment and Packing § 105.45 Use of...

2010-01-01

153

Technical Specification for a 25 Mv Tandem Electrostatic Accelerator.  

National Technical Information Service (NTIS)

Specifications are given for an accelerator system to consist of a 25 MV tandem electrostatic accelerator and specified ancillary equipment, including an injector, a beam transport system, a vacuum system, a control system, and a system for storage of the...

C. M. Jones J. A. Biggerstaff J. K. Blair J. B. Ball J. D. Larson

1975-01-01

154

Solar-to-Chemical Energy Conversion with Photoelectrochemical Tandem Cells.  

PubMed

Efficiently and inexpensively converting solar energy into chemical fuels is an important goal towards a sustainable energy economy. An integrated tandem cell approach could reasonably convert over 20% of the sun's energy directly into chemical fuels like H2 via water splitting. Many different systems have been investigated using various combinations of photovoltaic cells and photoelectrodes, but in order to be economically competitive with the production of H2 from fossil fuels, a practical water splitting tandem cell must optimize cost, longevity and performance. In this short review, the practical aspects of solar fuel production are considered from the perspective of a semiconductor-based tandem cell and the latest advances with a very promising technology - metal oxide photoelectrochemical tandem cells - are presented. PMID:23574955

Sivula, Kevin

2013-01-01

155

Tandem Interference Effects for Noncavitating and Supercavitating Hydrofoils.  

National Technical Information Service (NTIS)

Experimental data previously obtained at the St. Anthony Falls Hydraulic Laboratory relative to the tandem interference effects for noncavitating hydrofoils of finite span are compared with theory, and good agreement is shown to exist. The experimental st...

J. M. wetzel

1965-01-01

156

Outdoor stability performance of single and tandem amorphous silicon modules  

Microsoft Academic Search

Stability performance test results are presented for tests conducted at SERI on single and tandem amorphous silicon solar cell modules and submodules made by various manufacturers. Two sets of commercially available first-generation single-junction amorphous silicon solar cell modules manufactured by two different manufacturers, one single-junction submodule fabricated under a SERI subcontract, and one tandem amorphous silicon research submodule fabricated by

L. Mrig; S. Rummel; D. Waddington; R. DeBlasio

1988-01-01

157

Hydrodynamic studies on two traveling wavy foils in tandem arrangement  

Microsoft Academic Search

In this study, the hydrodynamic interactions between two tandem foils undergoing fishlike swimming motion are investigated numerically by solving the Navier-Stokes equations with the immersed-boundary method. The two foils represent two tandem propellers attached on a concept ship. The thrusts and efficiencies at three typical Strouhal numbers, i.e., St=0.4, 0.6, and 0.8, are investigated. The results show that a fish

Jian Deng; Xue-Ming Shao; Zhao-Sheng Yu

2007-01-01

158

LLNL tandem mirror experiment (TMX) upgrade vacuum system  

Microsoft Academic Search

The tandem mirror experiment (TMX) upgrade is a large, tandem, magnetic-mirror fusion experiment with stringent requirements on base pressure (10⁻⁸ Torr), low H reflux from the first walls, and peak gas pressure (5 x 10⁻⁷ Torr) due to neutral beam gas during plasma operation. The 225 m³ vacuum vessel is initially evacuated by turbopumps. Cryopumps provide a continuous sink for

W. L. Pickles; A. K. Chargin; R. P. Drake; A. L. Hunt; D. D. Lang; J. J. Murphy; P. Poulsen; T. C. Simonen; T. H. Batzer; T. P. Stack; R. L. Wong

1982-01-01

159

Reflectance modulator based on tandem Fabry-Perot resonators  

Microsoft Academic Search

We present calculations and data on a novel, electrically tunable reflector structure consisting of tandem Fabry–Perot resonators grown as a single epitaxial device. The device consists of three mirrors (quarter-wave stacks of AlGaAs and AlAs) separated by two cavities (one an AlGaAs alloy and the other a GaAs\\/AlGaAs superlattice) on a GaAs substrate. The tandem cavities produce a characteristic double-dipped

I. J. Fritz; J. F. Klem; J. R. Wendt

1991-01-01

160

Reflectance modulator based on tandem Fabry-Perot resonators  

Microsoft Academic Search

We present calculations and data on a novel, electrically tunable reflector structure consisting of tandem Fabry--Perot resonators grown as a single epitaxial device. The device consists of three mirrors (quarter-wave stacks of AlGaAs and AlAs) separated by two cavities (one an AlGaAs alloy and the other a GaAs\\/AlGaAs superlattice) on a GaAs substrate. The tandem cavities produce a characteristic double-dipped

I. J. Fritz; J. F. Klem; J. R. Wendt

1991-01-01

161

Ion Transport in Real and Velocity Space and Confinement in the GAMMA 10 Tandem Mirror  

NASA Astrophysics Data System (ADS)

Loss regions in the plasma particles' velocity space are decreased by the electrostatic potentials created on both sides of the plasma, which results in the improvement of the axial confinement in the tandem mirror. We found experimentally that the ion loss region was in contact mainly with both a plug potential bounce region and the outer mirror throat bounce region in which ions were bounced near the outer mirror throat of the plug/barrier cell. These bounce ions play an important role in tandem mirror confinement. The outer mirror throat bounce region is caused by the relatively high potential in the neighborhood of the outer mirror throat. The core plasma's radial potential profile was controlled by changing the potential of coaxially separated end plates, and it was found that control of the radial potential profile was useful for retardation of the radial loss of the bounce ions. We observed a hump structure on the energy distribution function of the end-loss ions, and found that the enhancement of the end-loss ions was caused by ion flow from the trapped region to the loss region due to Alfvn Ion Cyclotron (AIC) fluctuations. Although the ion diffusion due to the fluctuations enhances the axial ion loss, the axial loss can be reduced by creation of a higher confining potential.

Ishii, Kameo; Itakura, Akiyosi; Ichimura, Makoto; Katanuma, Isao; Kawamori, Eiichirou; Kohagura, Junko; Saito, Teruo; Takemura, Yuichiro; Tatematsu, Yoshinori; Cho, Teruji; Nakashima, Yousuke; Higaki, Hiroyuki; Hirata, Mafumi; Hojo, Hitoshi; Yatsu, Kiyoshi; Yoshikawa, Masayuki

162

Very high open-circuit voltage of 5.89 V in organic solar cells with 10-fold-tandem structure  

NASA Astrophysics Data System (ADS)

Organic solar cells (OSCs) based on chloroaluminum phthalocyanine (ClAlPc) as donor and fullerene C60 as acceptor with a multi-tandem structure were fabricated. We demonstrated very high open-circuit voltage (VOC) and enhanced power conversion efficiency (PCE) for the multi-tandem OSCs. Using a fivefold structure, we obtained PCE of 2.49% with a VOC of 3.50 V, in comparison with PCE of ~2% and VOC of 0.72-0.81 V for the single device. We also fabricated a tenfold-stacked OSC showing an extremely high VOC of 5.89 V. The multi-tandem OSCs with very high VOC have great potential for applications in limited-area low-power electronics.

Zou, Ye; Deng, Zhenbo; Potscavage, William J.; Hirade, Masaya; Zheng, Yanqiong; Adachi, Chihaya

2012-06-01

163

Intragenic tandem repeat variation between Legionella pneumophila strains  

PubMed Central

Background Bacterial genomes harbour a large number of tandem repeats, yet the possible phenotypic effects of those found within the coding region of genes are only beginning to be examined. Evidence exists from other organisms that these repeats can be involved in the evolution of new genes, gene regulation, adaptation, resistance to environmental stresses, and avoidance of the immune system. Results In this study, we have investigated the presence and variability in copy number of intragenic tandemly repeated sequences in the genome of Legionella pneumophila, the etiological agent of a severe pneumonia known as Legionnaires' disease. Within the genome of the Philadelphia strain, we have identified 26 intragenic tandem repeat sequences using conservative selection criteria. Of these, seven were "polymorphic" in terms of repeat copy number between a large number of L. pneumophila serogroup 1 strains. These strains were collected from a wide variety of environments and patients in several geographical regions. Within this panel of strains, all but one of these seven genes exhibited statistically different patterns in repeat copy number between samples from different origins (environmental, clinical, and hot springs). Conclusion These results support the hypothesis that intragenic tandem repeats could play a role in virulence and adaptation to different environments. While tandem repeats are an increasingly popular focus of molecular typing studies in prokaryotes, including in L. pneumophila, this study is the first examining the difference in tandem repeat distribution as a function of clinical or environmental origin.

Coil, David A; Vandersmissen, Liesbeth; Ginevra, Christophe; Jarraud, Sophie; Lammertyn, Elke; Anne, Jozef

2008-01-01

164

Tandem immuno-assay for cancer  

US Patent & Trademark Office Database

The identification and characterization of risk factors and their molecular implications in the pathophysiology of human diseases such as cancer is essential for designing efficient diagnostic assays and therapeutic compounds. Estrogenic steroids, under normal physiological conditions, have been shown to play a critical function in several tissues. The response of such a variety of tissues to estrogen stimulation can explain in part its active role in the development and progression of different human diseases, particularly breast cancer. Searching for estrogen-responding cellular factors in parental cells of primary human breast carcinomas obtained from tumour biopsies, two cellular markers, an isoenzyme of putative leucine aminopeptidase (LAPase; EC 3.4.11.1) from parental cells of primary human breast carcinomas obtained from tumour biopsies, and cytosolic NDP-Kinase/Nm23 (EC 2.7.4.6) from HL60 cells were identified. Monoclonal antibodies against each cellular marker have been produced. Determination of the presence of these two markers, either alone or in combination, -can be used to detect breast cancer, and in particular, associated metastatis. Thus, this invention refers to the use of both LAP and NDP-Kinase/Nm23 monoclonal antibodies together in a tandem solid-matrix based immuno-assay for first line confimatory blood-based testing for breast cancer.

2003-02-18

165

Small, octopole-stabilized tandem mirror reactor  

SciTech Connect

It is shown that the use of octopole stabilization in a tandem mirror allows a large reduction in end-cell length. A novel feature of the method proposed in this report is the placement of the minimum IBI region coonsiderably off axis, thus rendering the core plasma more axisymmetric. The region from the core to the field minimum is bridged by a mirror-confined hot-electron mantle. Low ..beta.., ideal magnetohydrodynamic stability, as evaluated with the interchange criterion, yields an upper limit to the required mantle peak ..beta.. of 78% for a center-cell peak ..beta.. of 75% and barrier peak ..beta.. of 30%. Estimates for the worst type of classical radial diffusion - with stochastic displacements per bounce - show that such radial losses are negligible for this configuration. First estimates of power balance indicate Q approx. 10 for a reactor producing 500 MW of fusion power and Q approx. 25 for one producing 1000 MW, using conservative assumptions regarding mantle ..beta.. requirements and synchrotron radiation losses.

Devoto, R.S.; Baldwin, D.E.; Logan, B.G.; Hamilton, G.W.; Johnston, B.W.

1984-10-03

166

The Impact of Genome Triplication on Tandem Gene Evolution in Brassica rapa  

PubMed Central

Whole genome duplication (WGD) and tandem duplication (TD) are both important modes of gene expansion. However, how WGD influences tandemly duplicated genes is not well studied. We used Brassica rapa, which has undergone an additional genome triplication (WGT) and shares a common ancestor with Arabidopsis thaliana, Arabidopsis lyrata, and Thellungiella parvula, to investigate the impact of genome triplication on tandem gene evolution. We identified 2,137, 1,569, 1,751, and 1,135 tandem gene arrays in B. rapa, A. thaliana, A. lyrata, and T. parvula respectively. Among them, 414 conserved tandem arrays are shared by the three species without WGT, which were also considered as existing in the diploid ancestor of B. rapa. Thus, after genome triplication, B. rapa should have 1,242 tandem arrays according to the 414 conserved tandems. Here, we found 400 out of the 414 tandems had at least one syntenic ortholog in the genome of B. rapa. Furthermore, 294 out of the 400 shared syntenic orthologs maintain tandem arrays (more than one gene for each syntenic hit) in B. rapa. For the 294 tandem arrays, we obtained 426 copies of syntenic paralogous tandems in the triplicated genome of B. rapa. In this study, we demonstrated that tandem arrays in B. rapa were dramatically fractionated after WGT when compared either to non-tandem genes in the B. rapa genome or to the tandem arrays in closely related species that have not experienced a recent whole genome polyploidization event.

Fang, Lu; Cheng, Feng; Wu, Jian; Wang, Xiaowu

2012-01-01

167

Hot-electron plasma formation and confinement in the tandem mirror experiment-upgrade  

SciTech Connect

The tandem mirror experiment-upgrade (TMX-U) at the Lawrence Livermore National Laboratory (LLNL) is the first experiment to investigate the thermal-barrier tandem-mirror concept. One attractive feature of the tandem magnetic mirror as a commercial power reactor is that the fusion reactions occur in an easily accessible center-cell. On the other hand, complicated end-cells are necessary to provide magnetohydrodynamic (MHD) stability and improved particle confinement of the center-cell plasma. In these end-cells, enhanced confinement is achieved with a particular axial potential profile that is formed with electron-cyclotron range-of-frequency heating (ECRF heating, ECRH). By modifying the loss rates of electrons at spatially distinct locations within the end-cells, the ECRH can tailor the plasma potential profile in the desired fashion. Specifically, the thermal-barrier concept requires generation of a population of energetic electrons near the midplane of each end-cell. To be effective, the transverse (to the magnetic field) spatial structure of the hot-electron plasma must be fairly uniform. In this dissertation we characterize the spatial structure of the ECRH-generated plasma, and determine how the structure builds up in time. Furthermore, the plasma should efficiently absorb the ECRF power, and a large fraction of the electrons must be well confined near the end-cell midplane. Therefore, we also examine in detail the ECRH power balance, determining how the ECRF power is absorbed by the plasma, and the processes through which that power is confined and lost. 43 refs., 69 figs., 6 tabs.

Ress, D.B.

1988-06-01

168

N, N-Dimethyl Leucines as Novel Isobaric Tandem Mass Tags for Quantitative Proteomics and Peptidomics  

PubMed Central

Herein we describe the development and application of a set of novel N, N-dimethyl leucine (DiLeu) 4-plex isobaric tandem mass (MS2) tagging reagents with high quantitation efficacy and greatly reduced cost for neuropeptide and protein analysis. DiLeu reagents serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency. DiLeu reagent resembles the general structure of a tandem mass tag in that it contains an amine reactive group (triazine ester) targeting the N-terminus and ?-amino group of the lysine side-chain of a peptide, a balance group, and a reporter group. A mass shift of m/z 145.1 is observed for each incorporated label. Intense a1 reporter ions at m/z 115.1, 116.1, 117.1, and 118.1 are observed for all pooled samples upon MS2. All labeling reagents are readily synthesized from commercially available chemicals with greatly reduced cost. Labels 117 and 118 can be synthesized in one step and labels 115 and 116 can be synthesized in two steps. Both DiLeu and iTRAQ reagents show comparable protein sequence coverage (~43%) and quantitation accuracy (<15%) for tryptically digested protein samples. Furthermore, enhanced fragmentation of DiLeu labeling reagents offers greater confidence in protein identification and neuropeptide sequencing from complex neuroendocrine tissue extracts from a marine model organism, Callinectes sapidus.

Xiang, Feng; Ye, Hui; Chen, Ruibing; Fu, Qiang; Li, Lingjun

2010-01-01

169

A strategy of gene overexpression based on tandem repetitive promoters in Escherichia coli  

PubMed Central

Background For metabolic engineering, many rate-limiting steps may exist in the pathways of accumulating the target metabolites. Increasing copy number of the desired genes in these pathways is a general method to solve the problem, for example, the employment of the multi-copy plasmid-based expression system. However, this method may bring genetic instability, structural instability and metabolic burden to the host, while integrating of the desired gene into the chromosome may cause inadequate transcription or expression. In this study, we developed a strategy for obtaining gene overexpression by engineering promoter clusters consisted of multiple core-tac-promoters (MCPtacs) in tandem. Results Through a uniquely designed in vitro assembling process, a series of promoter clusters were constructed. The transcription strength of these promoter clusters showed a stepwise enhancement with the increase of tandem repeats number until it reached the critical value of five. Application of the MCPtacs promoter clusters in polyhydroxybutyrate (PHB) production proved that it was efficient. Integration of the phaCAB genes with the 5CPtacs promoter cluster resulted in an engineered E.coli that can accumulate 23.7% PHB of the cell dry weight in batch cultivation. Conclusions The transcription strength of the MCPtacs promoter cluster can be greatly improved by increasing the tandem repeats number of the core-tac-promoter. By integrating the desired gene together with the MCPtacs promoter cluster into the chromosome of E. coli, we can achieve high and stale overexpression with only a small size. This strategy has an application potential in many fields and can be extended to other bacteria.

2012-01-01

170

Dynamic landscape of tandem 3? UTRs during zebrafish development  

PubMed Central

Tandem 3? untranslated regions (UTRs), produced by alternative polyadenylation (APA) in the terminal exon of a gene, could have critical roles in regulating gene networks. Here we profiled tandem poly(A) events on a genome-wide scale during the embryonic development of zebrafish (Danio rerio) using a recently developed SAPAS method. We showed that 43% of the expressed protein-coding genes have tandem 3? UTRs. The average 3? UTR length follows a V-shaped dynamic pattern during early embryogenesis, in which the 3? UTRs are first shortened at zygotic genome activation, and then quickly lengthened during gastrulation. Over 4000 genes are found to switch tandem APA sites, and the distinct functional roles of these genes are indicated by Gene Ontology analysis. Three families of cis-elements, including miR-430 seed, U-rich element, and canonical poly(A) signal, are enriched in 3? UTR-shortened/lengthened genes in a stage-specific manner, suggesting temporal regulation coordinated by APA and trans-acting factors. Our results highlight the regulatory role of tandem 3? UTR control in early embryogenesis and suggest that APA may represent a new epigenetic paradigm of physiological regulations.

Li, Yuxin; Sun, Yu; Fu, Yonggui; Li, Mengzhen; Huang, Guangrui; Zhang, Chenxu; Liang, Jiahui; Huang, Shengfeng; Shen, Gaoyang; Yuan, Shaochun; Chen, Liangfu; Chen, Shangwu; Xu, Anlong

2012-01-01

171

De novo sequencing of peptides on single resin beads by MALDI-FTICR tandem mass spectrometry.  

PubMed

An efficient approach in combinatorial chemistry is the synthesis of one-bead-one-compound peptide libraries. In contrast to synthesis and functional screening, which is performed in a largely automated manner, structure determination has been frequently laborious and time-consuming. Here we report an approach for de novo sequencing of peptides on single beads by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) tandem mass spectrometry, using a resin with a photolinker for solid-phase peptide synthesis. Upon sorting out single beads, an efficient sample preparation on the MALDI target was developed that enables fragmentation upon irradiation of the bead-matrix mixture with the ultraviolet (UV)-MALDI laser, with enhanced yield of sequence-specific fragment ions at increased laser energy. This approach is illustrated by sequence determinations of two peptides from a library with sequences varying in a single amino acid; the feasibility with tandem-MS procedures and fragment ion assignment was ascertained by sustained off-resonance irradiation/collision induced dissociation (SORI/CID) and infrared multiphoton dissociation (IRMPD) fragmentation. PMID:19914846

Semmler, Angelika; Weber, Reinhold; Przybylski, Michael; Wittmann, Valentin

2009-10-12

172

Investigation of the transfection capability of cloned tandemly-repeated chicken anaemia virus DNA fragments.  

PubMed

Chicken anaemia virus (CAV) is an icosahedral virus, 25 nm in diameter, which, on the basis of its circular single-stranded DNA genome, has recently been classified in the family, Circoviridae. We have investigated whether infectious, monomeric CAV DNA from recombinant plasmids containing tandemly-repeated CAV replicative form (RF) DNAs, following transfection, was generated by homologous recombination or a replicational release mechanism involving rolling circle replication (RCR) of DNA. Experiments designed to locate the virus strand origin of RCR and/or sites of recombination were performed by sequence analyses of hybrid viruses generated after transfection with cloned tandemly-repeated RFs specified by the sequence-distinct Cux-1 and 26P4 isolates. Positive transfection results obtained from 2 recombinant plasmid constructs were shown to have resulted from homologous recombination occurring at different sites within the RF sequence. Three of 5 hybrid viruses analysed were "circularised" within the same 105 bp sequence, that contains four 19bp repeats and with which promoter/enhancer activity has been associated. This region may represent a novel origin or recombination hot-spot within the CAV genome. A distinctive cruciform-loop structure within the non-coding region was shown to contain an S1 nuclease-sensitive site, detected in CAV RF and in recombinant plasmids containing RF inserts. PMID:8856031

Todd, D; Creelan, J L; Meehan, B M; McNulty, M S

1996-01-01

173

Sites in the AAV5 capsid tolerant to deletions and tandem duplications.  

PubMed

Gene therapy vectors based on adeno-associated virus (AAV) have shown much promise in clinical trials for the treatment of a variety of diseases. However, the ability to manipulate and engineer the viral surface for enhanced efficiency is necessary to overcome such barriers as pre-existing immunity and transduction of non-target cells that currently limit AAV applications. Although single amino acid changes and peptide insertions at select sites have been explored previously, the tolerance of AAV to small deletions and tandem duplications of sequence has not been globally addressed. Here, we have generated a large, diverse library of >10(5) members containing deletions and tandem duplications throughout the viral capsid of AAV5. Four unique mutants were identified that maintain the ability to form viral particles, with one showing improved transduction on both 293T and BEAS-2B cells. This approach may find potential use for the generation of novel variants with improved and altered properties or in the identification of sites that are tolerant to insertions of targeting ligands. PMID:20102698

Hida, Kaoru; Won, Sang Y; Di Pasquale, Giovanni; Hanes, Justin; Chiorini, John A; Ostermeier, Marc

2010-01-25

174

Properties of tandem balloons connected by extendable suspension wires  

NASA Astrophysics Data System (ADS)

It is well known that tandem balloons have interesting properties, for example, a combination of a zero-pressure balloon and a super-pressure balloon which withstands high pressure can achieve the long-duration flight against the difference of the day-night temperature. Here, we studied the response of tandem balloons when we change the length of the suspension rope. For example, a tandem balloon with a large zero-pressure balloon and a small superpressure balloon, one can change the floating altitude of the zero-pressure balloon without changing the altitude of the supper-pressure balloon. We are going to show our results of the properties based on analytic calculation.

Saito, Yoshitaka

175

mreps: efficient and flexible detection of tandem repeats in DNA  

PubMed Central

The presence of repeated sequences is a fundamental feature of genomes. Tandemly repeated DNA appears in both eukaryotic and prokaryotic genomes, it is associated with various regulatory mechanisms and plays an important role in genomic fingerprinting. In this paper, we describe mreps, a powerful software tool for a fast identification of tandemly repeated structures in DNA sequences. mreps is able to identify all types of tandem repeats within a single run on a whole genomic sequence. It has a resolution parameter that allows the program to identify ‘fuzzy’ repeats. We introduce main algorithmic solutions behind mreps, describe its usage, give some execution time benchmarks and present several case studies to illustrate its capabilities. The mreps web interface is accessible through http://www.loria.fr/mreps/.

Kolpakov, Roman; Bana, Ghizlane; Kucherov, Gregory

2003-01-01

176

UPGRADE AND OPERATION OF THE BNL TANDEMS FOR RHIC INJECTION.  

SciTech Connect

One of the tandem Van de Graaffs (MP7) at Brookhaven National Laboratory (BNL) has successfully completed its first year as an injector for the Relativistic Heavy Ion Collider (RHIC). The tandem provided pulsed beam of Au{sup +32} (peak intensity 80 e{mu}A, 500{micro}s) with only 17 hours of downtime during a 5 month run. Improvements are being made to further increase the intensity of the gold beam for the experimental run starting in 2001. A second tandem Van de Graaff (MP6) has been extensively upgraded and can now reach a terminal voltage of over 14MV. A beamline has been constructed to transport the MP6 beam around MP7 and then connect to the existing MP7 beamlines. This has allowed MP6 to deliver beam to local target rooms for an outside user program, while MP7 has simultaneously injected RHIC. MP6 can also be used as an injector for RHIC.

STESKI,D.B.; ALESSI,J.; BENJAMIN,J.; CARLSON,C.; MANNI,M.; THIEBERGER,P.; WIPLICH,M.

2001-06-18

177

High-efficiency, low-cost crystalline tandem cells  

SciTech Connect

Computer analysis of crystalline solar cells indicates that a substantial increase in cell conversion efficiencies can be achieved by using two-cell, multi-bandgap tandem structures instead of single-junction cells. Practical AM1 efficiencies of about 30% at one sun and over 30% at multiple suns are to be expected. The further increases in efficiency calculated for a three-cell tandem structure are smaller and may not justify the added complexity. For inexpensive two-cell tandem modules, Si is preferred for the bottom cell, and the top cell material should have a bandgap of 1.75 to 1.80 eV. The GaAs-AlAs and GaAs-GaP systems are attractive candidates for the top cell.

Fan, J.C.C.

1983-05-01

178

Highly Loaded Fan by Using Tandem Cascade Rotor Blade  

NASA Astrophysics Data System (ADS)

For axial flow compressors and fans in the aircraft engines higher pressure ratio is required in order to attain the high thrust engines. In this study, the fan with the tandem cascades was introduced to increase the fan pressure ratio. The use of tandem cascades in the fan allows savings in length and weight and therefore a compact fan could be built. The design of fan with tandem cascades and the fan testing were carried out to develop the high pressure ratio fan for the Air Turbo Ramjet (ATR) propulsion system. The ATR is a combined cycle engine which performs like a turbojet engine at subsonic speeds and a ramjet at supersonic speeds. In particular, high fan pressure ratio contributes to increase the engine thrust during subsonic flight at which the engine does not make use of ram effect. The results of the fan testing indicate that the pressure ratio of 2.2 is achieved in single stage fan.

Hasegawa, Hiroaki; Suga, Shinya; Matsuoka, Akinori

179

Sequence Analysis of Native Oligosaccharides Using Negative ESI Tandem MS  

PubMed Central

Carbohydrates exhibit many physiologically and pharmacologically important activities, yet their complicated structure and sequence pose major analytical challenges. Although their structural complexity makes analysis of carbohydrate difficult, mass spectrometry (MS) with high sensitivity, resolution and accuracy has become a vital tool in many applications related to analysis of carbohydrates or oligosaccharides. This application is essentially based on soft ionization technique which facilitates the ionization and vaporization of large, polar and thermally labile biomolecules. Electrospray-ionization (ESI), one of the soft ionization technique, tandem MS has been used in the sequencing of peptides, proteins, lipids, nucleic acids and more recently carbohydrates. The development of the ESI and tandem MS has begun to make carbohydrate analysis more routine. This review will focus on the application of the ESI tandem MS for the sequence analysis of native oligosaccharides, including neutral saccharides with multiple linkages, and the uronic acid polymers, alginate and glycosaminoglycans structures containing epimers.

Zhang, Zhenqing; Linhardt, Robert J.

2012-01-01

180

Enhanced oil recovery system  

DOEpatents

All energy resources available from a geopressured geothermal reservoir are used for the production of pipeline quality gas using a high pressure separator/heat exchanger and a membrane separator, and recovering waste gas from both the membrane separator and a low pressure separator in tandem with the high pressure separator for use in enhanced oil recovery, or in powering a gas engine and turbine set. Liquid hydrocarbons are skimmed off the top of geothermal brine in the low pressure separator. High pressure brine from the geothermal well is used to drive a turbine/generator set before recovering waste gas in the first separator. Another turbine/generator set is provided in a supercritical binary power plant that uses propane as a working fluid in a closed cycle, and uses exhaust heat from the combustion engine and geothermal energy of the brine in the separator/heat exchanger to heat the propane.

Goldsberry, Fred L. (Spring, TX)

1989-01-01

181

Dosimetric Comparison of Tandem and Ovoids vs. Tandem and Ring for Intracavitary Gynecologic Applications  

SciTech Connect

We evaluated dosimetric differences in tandem and ovoid (TO) and tandem and ring (TR) gynecologic brachytherapy applicators. Seventeen patients with cervical cancer (Stages II-IV) receiving 3 high-dose-rate (HDR) brachytherapy applications (both TO and TR) were studied. Patients underwent computed tomography (CT) scans with contrast in bladder, and were prescribed 8 Gy to ICRU points A, with additional optimization goals of maintaining the pear-shaped dose distribution and minimizing bladder and rectum doses. Bladder and rectum point doses, mean, and maximum doses were calculated. Total treatment time and volumes treated to 95%, 85%, 50%, and 20% or the prescription dose were compared. There were no significant differences between TO and TR applicators in doses to prescription points or critical organs. However, there were significant differences (p < 0.001) between the applicators in treated volumes and total treatment time. The TO treated larger volumes over a longer time. Within each patient, when the applicators were compared, treated volumes were also found to be significantly different (p < 0.01, {chi}{sup 2}). Our results demonstrate that the 2 applicators, while delivering the prescribed dose to points A and keeping critical organ doses below tolerance, treat significantly different volumes. It is unclear if this difference is clinically meaningful. TO applicators may be treating surrounding healthy tissue unnecessarily, or TR applicators may be underdosing tumor tissue. Further investigation with appropriate imaging modalities is required for accurate delineation of target volumes. Clearly, the TO and TR are not identical, and should not be used interchangeably without further study.

Levin, Daphne [Division of Radiotherapy, Assuta Medical Centers, Tel-Aviv (Israel) and Oncology Institute, Sheba Medical Center, Tel-Hashomer (Israel)], E-mail: daphnelp@yahoo.com; Menhel, Janna; Rabin, Tanya; Pfeffer, M. Raphael; Symon, Zvi [Division of Radiotherapy, Assuta Medical Centers, Tel-Aviv (Israel) and Oncology Institute, Sheba Medical Center, Tel-Hashomer (Israel)

2008-01-01

182

Counter-Rotating Tandem Motor Drilling System  

SciTech Connect

Gas Technology Institute (GTI), in partnership with Dennis Tool Company (DTC), has worked to develop an advanced drill bit system to be used with microhole drilling assemblies. One of the main objectives of this project was to utilize new and existing coiled tubing and slimhole drilling technologies to develop Microhole Technology (MHT) so as to make significant reductions in the cost of E&P down to 5000 feet in wellbores as small as 3.5 inches in diameter. This new technology was developed to work toward the DOE's goal of enabling domestic shallow oil and gas wells to be drilled inexpensively compared to wells drilled utilizing conventional drilling practices. Overall drilling costs can be lowered by drilling a well as quickly as possible. For this reason, a high drilling rate of penetration is always desired. In general, high drilling rates of penetration (ROP) can be achieved by increasing the weight on bit and increasing the rotary speed of the bit. As the weight on bit is increased, the cutting inserts penetrate deeper into the rock, resulting in a deeper depth of cut. As the depth of cut increases, the amount of torque required to turn the bit also increases. The Counter-Rotating Tandem Motor Drilling System (CRTMDS) was planned to achieve high rate of penetration (ROP) resulting in the reduction of the drilling cost. The system includes two counter-rotating cutter systems to reduce or eliminate the reactive torque the drillpipe or coiled tubing must resist. This would allow the application of maximum weight-on-bit and rotational velocities that a coiled tubing drilling unit is capable of delivering. Several variations of the CRTDMS were designed, manufactured and tested. The original tests failed leading to design modifications. Two versions of the modified system were tested and showed that the concept is both positive and practical; however, the tests showed that for the system to be robust and durable, borehole diameter should be substantially larger than that of slim holes. As a result, the research team decided to complete the project, document the tested designs and seek further support for the concept outside of the DOE.

Kent Perry

2009-04-30

183

Tandem junction amorphous semiconductor photovoltaic cell  

DOEpatents

A photovoltaic stack comprising at least two p[sup +]i n[sup +] cells in optical series, said cells separated by a transparent ohmic contact layer(s), provides a long optical path for the absorption of photons while preserving the advantageous field-enhanced minority carrier collection arrangement characteristic of p[sup +]i n[sup +] cells. 3 figs.

Dalal, V.L.

1983-06-07

184

Tandem junction amorphous semiconductor photovoltaic cell  

DOEpatents

A photovoltaic stack comprising at least two p.sup.+ i n.sup.+ cells in optical series, said cells separated by a transparent ohmic contact layer(s), provides a long optical path for the absorption of photons while preserving the advantageous field-enhanced minority carrier collection arrangement characteristic of p.sup.+ i n.sup.+ cells.

Dalal, Vikram L. (Newark, DE)

1983-01-01

185

Speeding up tandem mass spectral identification using indexes  

PubMed Central

Motivation: Tandem mass spectrometry (MS/MS) has been routinely used in proteomics studies. Post-translational modification (PTM) identification is a challenging problem in tandem mass spectral analysis. Results: In this article, we define two scoring functions for identifying peptides/proteins with PTMs from MS/MS spectra: match scores and diagonal scores, as well as two spectral identification problems based on the two scores. We propose several index-based algorithms for the two problems. Both theoretical and experimental analyses show that the index-based algorithms significantly improve on speed when compared with existing algorithms. Contact: xil018@cs.ucsd.edu

Liu, Xiaowen; Mammana, Alessandro; Bafna, Vineet

2012-01-01

186

Summary of the MARS tandem-mirror reactor design  

SciTech Connect

A recently completed two-year study of a commercial tandem-mirror reactor design (Mirror Advanced Reactor Study (MARS)) is briefly reviewed. The end plugs are designed for trapped-particle stability, MHD ballooning, balanced geodesic curvature, and small radial electric fields in the central cell. New technologies such as lithium-lead blankets, 24 T hybrid coils, gridless direct converters and plasma halo vacuum pumps are highlighted. General characteristics of the MARS tandem mirror and STARFIRE tokamak reactor design are compared. A design of an upgrade of MFTF-B incorporating many of the MARS features is discussed.

Logan, B.G.

1983-09-01

187

Overview and direction in the tandem mirror program  

SciTech Connect

There are two main thrusts to the tandem mirror program at the present time. One is to gather the experimental data base to verify the axicell thermal barrier concept and the other to improve the end plugs for tandems. With such improvements one might approach the ideal fusion reactor, a simple solenoid of modular elements whose ends are but a modest perturbation on the configuration from both a cost and technological view point. Progress toward these two goals is discussed here, and the directions to be taken in the immediate future are described.

Thomassen, K.I.

1983-09-01

188

Overview and direction in the tandem mirror program  

SciTech Connect

There are two main thrusts to the tandem mirror program at the present time. One is to gather the experimental data base to verify the axicell thermal-barrier concept and the other to improve the end plugs for tandems. With such improvements one might approach the ideal fusion reactor, a simple solenoid of modular elements whose ends are but a modest perturbation on the configuration from both a cost and technological viewpoint. Progress toward these two goals is discussed here, and the directions to be taken in the immediate future are described.

Thomassen, K.I.

1983-04-01

189

Performance of F2T2 tandem tunable etalon  

NASA Astrophysics Data System (ADS)

COM DEV Ltd. is building a tandem tunable Fabry-Perot etalon to be mounted inside the Flamingos-2 imaging spectrograph on the Gemini South Telescope. The Flamingos-2 Tandem Tunable Filter has a target spectral resolution of R~800 and a clear aperture of 60 mm, and will be fed by the telescope's Multi-Conjugate Adaptive Optics system. The system is designed to undertake ultra-deep searches for "First-Light" sources at redshifts of z = 7-10 using foreground gravitational lensing. This paper describes preliminary characterization and expected performance F2T2.

Scott, Alan; Javed, Maniyar; Abraham, Roberto; Eikenberry, Steve; Barton, Elizabeth; Bershady, Matthew; Bland-Hawthorn, Joss; Crampton, David; Doyon, Rene; Julian, Jeff; Julian, Roger; Kneib, Jean-Paul; Loop, David; Raines, Nick; Rowlands, Neil; Smith, J. D.

2006-07-01

190

Tandem multipass Fabry-Perot interferometer for Brillouin scattering.  

PubMed

A new design of a plane mirror Fabry-Perot interferometer with the mirror blanks freely supported by horizontal rings is described. Special attention is paid to the surface flatness and dielectric coatings of the mirrors. It is shown that any two piezoelectrically scanned Fabry-Perot interferometers can be synchronized in tandem operation using simple optics and standard electronic driving and stabilization equipment. Applications of the tandem system to Brillouin scattering are given. The observation of Brillouin spectra of supported thin plastic films and of a clamped metal surface is reported. PMID:20309316

Dil, J G; van Hijningen, N C; van Dorst, F; Aarts, R M

1981-04-15

191

Binomial probability distribution model-based protein identification algorithm for tandem mass spectrometry utilizing peak intensity information.  

PubMed

Mass spectrometry has become one of the most important technologies in proteomic analysis. Tandem mass spectrometry (LC-MS/MS) is a major tool for the analysis of peptide mixtures from protein samples. The key step of MS data processing is the identification of peptides from experimental spectra by searching public sequence databases. Although a number of algorithms to identify peptides from MS/MS data have been already proposed, e.g. Sequest, OMSSA, X!Tandem, Mascot, etc., they are mainly based on statistical models considering only peak-matches between experimental and theoretical spectra, but not peak intensity information. Moreover, different algorithms gave different results from the same MS data, implying their probable incompleteness and questionable reproducibility. We developed a novel peptide identification algorithm, ProVerB, based on a binomial probability distribution model of protein tandem mass spectrometry combined with a new scoring function, making full use of peak intensity information and, thus, enhancing the ability of identification. Compared with Mascot, Sequest, and SQID, ProVerB identified significantly more peptides from LC-MS/MS data sets than the current algorithms at 1% False Discovery Rate (FDR) and provided more confident peptide identifications. ProVerB is also compatible with various platforms and experimental data sets, showing its robustness and versatility. The open-source program ProVerB is available at http://bioinformatics.jnu.edu.cn/software/proverb/ . PMID:23163785

Xiao, Chuan-Le; Chen, Xiao-Zhou; Du, Yang-Li; Sun, Xuesong; Zhang, Gong; He, Qing-Yu

2012-11-29

192

EXACTLY PERIODIC SUBSPACE DECOMPOSITION BASED APPROACH FOR IDENTIFYING TANDEM REPEATS IN DNA SEQUENCES  

Microsoft Academic Search

The identification and analysis of tandem repeats is an ac- tive area of biological and computational research. Tandem repetitive structures in telomeres plays a role in cancer and hyper-variable, trinucleotide tandem repeats are linked to over a dozen major degenerative diseases. They also play a very crucial role in DNA fingerprinting. In this paper we present an algorithm to identify

Ravi Gupta; Divya Sarthi; Ankush Mittal; Kuldip Singh

2006-01-01

193

47 CFR 69.713 - Common line, traffic-sensitive, and tandem-switched transport services.  

Code of Federal Regulations, 2011 CFR

...traffic-sensitive, and tandem-switched transport services. 69.713 Section 69...traffic-sensitive, and tandem-switched transport services. (a) Scope. This paragraph...traffic-sensitive components of tandem-switched transport services, as described in §§...

2011-10-01

194

47 CFR 69.713 - Common line, traffic-sensitive, and tandem-switched transport services.  

Code of Federal Regulations, 2012 CFR

...traffic-sensitive, and tandem-switched transport services. 69.713 Section 69...traffic-sensitive, and tandem-switched transport services. (a) Scope. This paragraph...traffic-sensitive components of tandem-switched transport services, as described in §§...

2012-10-01

195

Two-Step Recruitment of RNA-Directed DNA Methylation to Tandem Repeats  

Microsoft Academic Search

Tandem repeat sequences are frequently associated with gene silencing phenomena. The Arabidopsis thaliana FWA gene contains two tandem repeats and is an efficient target for RNA-directed de novo DNA methylation when it is transformed into plants. We showed that the FWA tandem repeats are necessary and sufficient for de novo DNA methylation and that repeated character rather than intrinsic sequence

Simon W.-L. Chan; Xiaoyu Zhang; Yana V. Bernatavichute; Steven E. Jacobsen

2006-01-01

196

Improving the efficiency of thin film tandem solar cells by plasmonic intermediate reflectors  

NASA Astrophysics Data System (ADS)

Thin film tandem solar cells made of amorphous and microcrystalline silicon provide renewable energy at the benefit of low material consumption. As a drawback, these materials do not posses the high carrier mobilities of their crystalline counterpart which limits the feasible material thickness. For maintaining the light absorption as high as possible, photon management is required. Here we show that metallic nanodiscs that sustain localized plasmon polaritons can increase the efficiency of such solar cells if they are incorporated into the dielectric intermediate reflector separating the top and the bottom cell. We provide quantitative estimates for the possible absorption enhancement of optimized bi-periodic nanodiscs that are feasible for fabrication. Emphasis is also put on discussing the impact of obliquely incident sun light on the solar cell performance.

Fahr, Stephan; Rockstuhl, Carsten; Lederer, Falk

2010-09-01

197

Energy-harvesting potential of multiple elastic structures in tandem arrangement  

NASA Astrophysics Data System (ADS)

Vortex-induced flapping vibrations of elastic structures attached with piezoelectric materials, i.e., ``piezo-leaves'', have recently been explored for its potential application in wind energy harvesting (e.g., Li, Yuan, and Lipson, J. Appl. Phys., 2011). In this work, we explore the possibility of enhancing the structural vibration and energy harvesting performance of the generator by putting the leaves in tandem arrangement and within close range of hydrodynamic interaction. A two-dimensional model is developed, where two or more elastic plates are mounted in a cross flow. In the case of two plates, the numerical simulation shows that at a particular distance, the vibration of the downstream plate is greatly increased, and so is the energy level of the entire system. For multiple plates, we observed both synchronized and apparently chaotic vibration modes. The characteristics of the vortex interaction, plate deformation, and energetics will be presented for those coupling modes.

Yin, Bo; Luo, Haoxiang

2011-11-01

198

Ultrafast amplification of DNA on plastic microdevices for forensic short tandem repeat analysis.  

PubMed

The majority of microfluidic devices used as a platform for low-cost, rapid DNA analysis are glass devices; however, microchip fabrication in glass is costly and laborious, enhancing the interest in polymeric substrates, such as poly (methyl methacrylate) (PMMA), as an inexpensive alternative. Here, we report amplification in PMMA polymerase chain reaction (PCR) microchips providing full short tandem repeat profiles (16 of 16 loci) in 30-40 min, with peak height ratios and stutter percentages that meet literature threshold requirements. In addition, partial profiles (15 of 16 loci) were generated using an ultrafast PCR method in 17.1 min, representing a ~10-fold reduction in reaction time as compared to current amplification methods. Finally, a multichamber device was demonstrated to simultaneously amplify one positive, one negative, and five individual samples in 39 min. Although there were instances of loci dropout, this device represents a first step toward a microfluidic system capable of amplifying more than one sample simultaneously. PMID:23692541

Lounsbury, Jenny A; Landers, James P

2013-05-21

199

C60/N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine:MoO3 as the interconnection layer for high efficient tandem blue fluorescent organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

The high efficient tandem blue fluorescent organic light emitting diodes (OLEDs) with the transparent interconnection layer (ICL) of fullerence (C60)/Molybdenum oxide (MoO3)-doped N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) were presented. A stack consisting of 0.5 nm of LiF and 1 nm of Ca, which is located from C60 to adjacent electron transporting layer is used as an electron injection layer. The experiment results indicate that the luminance of the tandem device is basically equal to that of the traditional single-unit device, but the current density of the tandem device is much less than that of the single-unit device under a same luminance. The current efficiency and the maximal power efficiency of tandem device with LiF/Ca/C60/NPB:MoO3/MoO3-based interconnection layer have been approximately enhanced by 250% and 126%, respectively. In addition, we also analyze that the mechanism of the efficiency enhancement is ascribed to the effective charge separation and transport of the ICL in tandem OLEDs.

Wu, Xiaoming; Bi, Wentao; Hua, Yulin; Sun, Jin'e.; Xiao, Zhihui; Wang, Li; Yin, Shougen

2013-06-01

200

Combining two-directional synthesis and tandem reactions, part 11: second generation syntheses of (?)-hippodamine and (?)-epi-hippodamine  

PubMed Central

Background Hippodamine is a volatile defence alkaloid isolated from ladybird beetles which holds potential as an agrochemical agent and was the subject of a synthesis by our group in 2005. Results Two enhancements to our previous syntheses of (±)-hippodamine and (±)-epi-hippodamine are presented which are able to shorten the syntheses by up to two steps. Conclusion Key advances include a two-directional homologation by cross metathesis and a new tandem reductive amination/double intramolecular Michael addition which generates 6 new bonds, 2 stereogenic centres and two rings, giving a single diastereomer in 74% yield.

Newton, Annabella F; Rejzek, Martin; Alcaraz, Marie-Lyne; Stockman, Robert A

2008-01-01

201

Silicon quantum dot nanostructures for tandem photovoltaic cells  

Microsoft Academic Search

Tandem PV cells – with their increased efficiency due to a multi-band gap approach – usually involve expensive materials and fabrication. Thin film approaches, with an engineered variation in band gap through the use of quantum confinement in Si quantum dots, offer a cheaper alternative. Presented are characterisation and modelling data on fabrication of such Si and Sn QD nanostructures

Gavin Conibeer; Martin Green; Eun-Chel Cho; Dirk König; Young-Hyun Cho; Thipwan Fangsuwannarak; Giuseppe Scardera; Edwin Pink; Yidan Huang; Tom Puzzer; Shujuan Huang; Dengyuan Song; Chris Flynn; Sangwook Park; Xiaojing Hao; Daniel Mansfield

2008-01-01

202

Tandem Hypnosis with Identical Bulimic Twins: Case Report  

Microsoft Academic Search

Hypnosis has been used in the treatment of bulimia nervosa from the early 1980s. Dissociation theory identified a certain subgroup of eating disordered patients with dissociative signs and symptoms. These patients react well to hypnotherapy. Simultaneous hypnosis (“tandem hypnosis”) in the treatment of two female 19-year-old monozygotic twins led to a very successful outcome after 6 sessions. During the therapy,

Ferenc Túry; Márta Wildmann; Annanmária Szentes

2011-01-01

203

Orbit averaged radial buildup code for tandem mirror geometry  

Microsoft Academic Search

The radial Fokker-Planck (RFP) model of A. Futch was modified to treat plasma buildup in the tandem mirror plug and center cell with a self-consistent model (TOARBUC). Two major changes have been made to the original version of this code. First, the center cell is treated as having separate electron and ion confining potentials with the ion potential having the

M. Campbell; A. H. Futch

1981-01-01

204

Application of Fully Digital Speed Regulators to Tandem Cold Mills  

Microsoft Academic Search

A fully digital speed regulator has been developed for industrial applications mainly in the steel industry. The benefits obtained when the digital speed regulator was used in two different tandem cold rolling mill control systems are described. As compared with conventional analog control, fully digital speed control permitted more stable rolling mill operation, reducing both threading and accelerating times by

Keiji Saito; Haruo Nagasaki; Katsuhiko Doi; Shigemichi Matsuka; Kenzo Kamiyama

1984-01-01

205

Recent Activities at Centro Informazioni Studi Esperienze Tandem.  

National Technical Information Service (NTIS)

Installation improvements in a radiation damage, PIXE, and backscattering analysis laboratory are described; in particular the 3.5 MV CISE Tandem computer control center which is based on a S130 Eclipse central controller and Z80A microprocessor local con...

E. Caruso F. Cristofori

1980-01-01

206

Acceptance of the Rossendorf EGP-10-1 Tandem Accelerator.  

National Technical Information Service (NTIS)

A description of the computer code AKZEPTANZ is given. Using this code the first-order acceptance areas of the Rossendorf EGP-10-1 tandem accelerator have been calculated. At an injection energy of 23 keV they are practically independent of the terminal v...

R. Hentschel

1980-01-01

207

Tandem Towing Tests of the MHU-12/M Trailer.  

National Technical Information Service (NTIS)

Two MHU-12/M Trailers in tandem behind a 1-1/2-ton truck were subjected to braking and road tests on roads of various surface conditions at speeds to 20 miles per hour. Three load conditions of the trailers were used in the tests: unloaded, a low center-o...

G. W. Gray

1974-01-01

208

Electron Heat Conduction in the Phaedrus Tandem Mirror  

Microsoft Academic Search

Experiments to investigate electron heat conduction have been performed on the University of Wisconsin tandem mirror Phaedrus. Electron temperature differences along the magnetic field were generated using a mircowave heat pulse. Probe techniques were developed for the continuous measurement of local electron temperatures with a time resolution of less than one microsecond. Parameter studies indicated that the temperature differences were

Donna Lynn Smatlak

1982-01-01

209

Mycotoxin analysis by fast atom bombardment tandem mass spectrometry.  

PubMed

Positive fast atom bombardment tandem mass spectrometry is demonstrated to be an effective technique for determination of crude aflatoxins and sterigmatocystin-related compounds. The molecular ion was selected by the first system and bombarded to produce characteristic daughter ions that could be used to identify mycotoxins in mixtures and with the same molecular weight. PMID:2745376

Uyakul, D; Isobe, M; Goto, T

210

Tandem Mass Spectrometry and Newborn Screening: Pilot Data and Review  

Microsoft Academic Search

United States legislatures are debating whether to use tandem mass spectrometry to expand the roster of inherited disorders tested in newborn screening pro- grams. The debate is hampered because published finan- cial data comparing charges associated with late vs early diagnosis are not readily available. We provide pilot financial data comparing late diagnosis vs presumptive diagnosis and early management taken

James J. Filiano; Sherry Gray Bellimer; Pamela L. Kunz

211

Radial confinement of central cell plasma in tandem mirrors  

Microsoft Academic Search

The single particle guiding center orbit analysis is carried out both numerically and analytically. It is demonstrated numerically using the magnetic field geometry and plasma parameters of the tandem reactor. The radial losses of particle and energy are studied in the fluid approximation. A set of transport equations are obtained by assuming the magnetic field in the three mirror cells

L. I. Lao

1979-01-01

212

Magnetic Ripple Correction in Tandem Mirrors by Ferromagnetic Inserts.  

National Technical Information Service (NTIS)

Magnetic ripple of 1% or more caused by discrete solenoid coils in the central cells of tandem mirrors may severely affect the MHD stability. The ripple amplitude can be reduced by an order of magnitude by ferromagnetic annuli inserted within the coils at...

G. W. Hamilton

1985-01-01

213

ORIC stripping foil positioner for tandem beam injection  

SciTech Connect

The Oak Ridge Isochronous Cyclotron (ORIC) is used as an energy booster for heavy ions from a 25 MV tandem accelerator. This operation requires precise placement of a stripping foil in the cyclotron for capture of the injected ions into an acceleration orbit. The mechanical design and control of the foil positioning device are described.

Ludemann, C.A.; Lord, R.S.; Hudson, E.D.; Irwin, F.; Beckers, R.M.; Haynes, D.L.; Casstevens, B.J.; Mosko, S.W.

1981-01-01

214

Interactions of tandem square cylinders at low Reynolds numbers  

Microsoft Academic Search

Two identical square cylinders were installed in tandem in a vertical water tank. The effects of the Reynolds number, spacing ratio and rotation angle of the downstream cylinder on flow characteristic modes, drag coefficients and vortex shedding properties were studied. The particle image velocimetry (PIV) scheme was applied to examine and classify the flow field into three characteristic modes: vortex

S. C. Yen; K. C. San; T. H. Chuang

2008-01-01

215

LLNL Tandem Mirror Experiment (TMX) Upgrade Vacuum System.  

National Technical Information Service (NTIS)

TMX Upgrade is a large, tandem, magnetic-mirror fusion experiment with stringent requirements on base pressure (10 exp -8 torr), low H reflux from the first walls, and peak gas pressure (5 x 10 exp -7 torr) due to neutral beam gas during plasma operation....

W. L. Pickles A. K. Chargin R. P. Drake

1981-01-01

216

Mechanical design of the Tandem Mirror Experiment Upgrade vacuum system  

Microsoft Academic Search

The Tandem Mirror Experiment Upgrade (TMX Upgrade) vacuum system uses most of the vacuum system from the original TMX and substantially increases its capabilities. The vacuum system provides the main structure for the experimental apparatus, as well as providing and maintaining the vacuum environment. The vacuum vessel provides the structure supporting all magnets, as they are contained inside the vacuum

D. D. Lang; M. O. Calderon; S. R. Thomas; D. R. Garner

1981-01-01

217

Human tandem repeat sequences in forensic DNA typing  

Microsoft Academic Search

It has been 20 years since the first development of DNA fingerprinting and the start of forensic DNA typing. Ever since, human tandem repeat DNA sequences have been the main targets for forensic DNA analysis. These repeat sequences are classified into minisatellites (or VNTRs) and microsatellites (or STRs). In this brief review, we discuss the historical and current forensic applications

Keiji Tamaki; Alec J. Jeffreys

2005-01-01

218

MINIMARS: An attractive small tandem mirror fusion reactor  

Microsoft Academic Search

Through the innovative design of a novel end plug scheme employing octopole MHD stabilization, we present the conceptual design of MINIMARS, a small commercial fusion reactor based on the tandem mirror principle. The current baseline for MINIMARS has a net electric output of 600 MWe and we have configured the design for short construction times, factory-built modules, inherently safe blanket

L. J. Perkins; B. G. Logan; J. N. Doggett; R. S. Devoto; W. D. Nelson; D. C. Lousteau; G. L. Kulcinski; J. F. Santarius; J. D. Gordon; R. B. Campbell

1985-01-01

219

Ohio University Tandem van de Graaff Accelerator. Final Report.  

National Technical Information Service (NTIS)

A summary is given of the work carried out at the John Edwards Tandem Accelerator Laboratory of Ohio University during the period 1970 to 1977 on studies of neutron-nucleus interactions and nuclear structure using neutrons as probes. This work utilizes th...

R. O. Lane

1977-01-01

220

Accelerator mass spectrometry with a coupled tandem-linac system  

SciTech Connect

A coupled system provides higher energies, which allows one to extend AMS to hitherto untouched mass regions. Another important argument is that the complexity, although bothersome for the operation, increases the selectivity of detecting a particular isotope. The higher-energy argument holds for any heavy-ion accelerator which is capable of delivering higher energy than a tandem. The present use of tandem-linac combinations for AMS, rather than cyclotrons, linacs or combinations of these machines, has mainly to do with the fact that this technique was almost exclusively developed around tandem accelerators. Therefore the tandem-linac combination is a natural extension to higher energies. The use of negative ions has some particular advantages in suppressing background from unwanted elements that do not form stable negative ions (e.g., N, Mg, Ar). On the other hand, this limits the detection of isotopes to elements which do form negative ions. For particular problems it may therefore be advantageous to use a positive-ion machine. What really matters most for choosing one or the other machine is to what extent the entire accelerator system can be operated in a truly quantiative way from the ion source to the detection system. 20 references, 4 figures.

Kutschera, W.

1984-01-01

221

An unprecedented, tandem Aldol-Grob reaction sequence  

Microsoft Academic Search

The authors report an unprecedented, tandem Aldol-Grob sequence involving the reaction of ketones with aromatic aldehydes in nonnucleophilic solvents in the presence of boron trifluoride. Although a detailed study of the reaction mechanism has not yet been completed, the consistent formation of (E)-alkene products, as well as the fact that aromatic aldehydes appear to be required, would point toward the

George W. Kabalka; David Tejedor; Nan-Sheng Li; Rama R. Malladi; Sarah Trotman

1998-01-01

222

Simple tandem DNA repeats and human genetic disease  

SciTech Connect

The human genome contains many repeated DNA sequences that vary in complexity of repeating unit from a single nucleotide to a whole gene. The repeat sequences can be widely dispersed or in simple tandem arrays. Arrays of up to 5 or 6 nt are known as simple tandem repeats, and these are widely dispersed and highly polymorphic. Members of one group of the simple tandem repeats, the trinucleotide repeats, can undergo an increase in copy number by a process of dynamic mutation. Dynamic mutations of the CCG trinucleotide give rise to one group of fragile sites on human chromosomes, the rare folate-sensitive group. One member of this group, the fragile X (FRAXA) is responsible for the most common familial form of mental retardation. Another member of the group FRAXE is responsible for a rarer mild form of mental retardation. Similar mutations of AGC repeats give rise to a number of neurological disorders. The expanded repeats are unstable between generations and somatically. The intergenerational instability gives rise to unusual patterns of inheritance - particularly anticipation, the increasing severity and/or earlier age of onset of the disorder in successive generations. Dynamic mutations have been found only in the human species, and possible reasons for this are considered. The mechanism of dynamic mutation is discussed, and a number of observations of simple tandem repeat mutation that could assist in understanding this phenomenon are commented on.

Sutherland, G.R.; Richards, R.I. [Women`s and Children`s Hospital, Adelaide (Australia)

1995-04-25

223

Tandem modifications of an epoxyquinone C7N pharmacophore.  

PubMed

C7N moieties are wildly present as pharmacophores in natural products. In this issue of Chemistry & Biology, Rui and colleagues biochemically reproduced the initiation event of asukamycin biosynthesis and characterized tandem enzymatic oxygenations of the epoxyquinone C7N moiety. PMID:23890003

Bai, Linquan

2013-07-25

224

Wide spectral bandwidth electro-absorption modulator using coupled micro-cavity with asymmetric tandem quantum well.  

PubMed

For reliable three dimensional (3D) imaging system, it is necessary for the optical shutter to have a wide spectral bandwidth operation and enhanced modulation depth. We propose an electro-absorption modulator (EAM) based on coupled Fabry-Perot cavities with micro-cavity (CCMC) which uses asymmetric tandem quantum wells (ATQWs) to obtain improved spectral bandwidth and enhanced modulation depth. Several modulator designs are investigated to obtain improved modulation performance such as wider spectral bandwidth and enhanced modulation depth. It was found that among all the studied modulator geometries, CCMC structure with ATQWs provides the widest spectral bandwidth of 9.6nm and high modulation depth in excess of 50% at -24V, which is good agreement with theoretical calculations. These results suggest that EAM has excellent potential as optical shutter for 3D imaging application. PMID:23038593

Na, Byung Hoon; Ju, Gun Wu; Choi, Hee Ju; Cho, Yong Chul; Park, Yong Hwa; Park, Chang Young; Lee, Yong Tak

2012-08-13

225

An intron enhancer activates the immunoglobulin-related Hemolin gene in Hyalophora cecropia.  

PubMed

Hemolin is the only insect member of the immunoglobulin (Ig) superfamily reported to be up-regulated during an immune response. In diapausing pupae of Hyalophora cecropia the gene is expressed in fat body cells and in haemocytes. Like the mammalian Ig kappa light chain gene, the Hemolin gene harbours an enhancer including a kappaB motif in one of its introns. This motif binds the H. cecropia Rel factor Cif (Cecropia immunoresponsive factor). The Hemolin third intron also mediates transient reporter gene expression in immunoresponsive Drosophila mbn-2 cells. Co-transfections of Drosophila SL2 cells showed that the Drosophila Rel factor Dif (Dorsal-related immunity factor), transactivates reporter gene constructs through the intron. Moreover, a 4.8-fold synergistic activation was obtained when Dif is combined with the rat C/EBP (CCAAT/enhancer element-binding protein) and human HMGI (high mobility group protein I). This is the first report of an insect immune-related gene that is up-regulated by an enhancer activity conferred through an intron. PMID:12230549

Roxström-Lindquist, K; Lindström-Dinnetz, I; Olesen, J; Engström, Y; Faye, I

2002-10-01

226

Large tandem repeats make up the chromosome bar code: a hypothesis.  

PubMed

Much of tandem repeats' functional nature in any genome remains enigmatic because there are only few tools available for dissecting and elucidating the functions of repeated DNA. The large tandem repeat arrays (satellite DNA) found in two mouse whole-genome shotgun assemblies were classified into 4 superfamilies, 8 families, and 62 subfamilies. With the simplified variant of chromosome positioning of different tandem repeats, we noticed the nonuniform distribution instead of the positions reported for mouse major and minor satellites. It is visible that each chromosome possesses a kind of unique code made up of different large tandem repeats. The reference genomes allow marking only internal tandem repeats, and even with such a limited data, the colored "bar code" made up of tandem repeats is visible. We suppose that tandem repeats bare the mechanism for chromosomes to recognize the regions to be associated. The associations, initially established via RNA, become fixed by histone modifications (the histone or chromatin code) and specific proteins. In such a way, associations, being at the beginning flexible and regulated, that is, adjustable, appear as irreversible and inheritable in cell generations. Tandem repeat multiformity tunes the developed nuclei 3D pattern by sequential steps of associations. Tandem repeats-based chromosome bar code could be the carrier of the genome structural information; that is, the order of precise tandem repeat association is the DNA morphogenetic program. Tandem repeats are the cores of the distinct 3D structures postulated in "gene gating" hypothesis. PMID:23582200

Podgornaya, Olga; Gavrilova, Ekaterina; Stephanova, Vera; Demin, Sergey; Komissarov, Aleksey

2013-01-01

227

Tumor necrosis factor. alpha. induces proteins that bind specifically to. kappa. B-like enhancer elements and regulate interleukin 2 receptor. alpha. -chain gene expression in primary human T lymphocytes  

SciTech Connect

The authors have investigated the biochemical basis for the activation of interleukin 2 receptor {alpha}-subunit (IL-2R{alpha}) gene expression in primary human T lymphocytes by a cytokine (tumor necrosis factor {alpha}), a T-cell mitogen (phorbol 12-myristate 13-acetate), and the transactivator protein (Tax) from the type I human T-cell leukemia virus. Using in vivo transfection techniques specifically designed for these primary T cells in conjunction with in vitro gel retardation and DNA footprinting assays, the authors found that activation of the IL-2R{alpha} promoter by each of these agents involves the induction of nuclear proteins that specifically interact with a {kappa}B-like enhancer element. DNA-protein crosslinking studies revealed that primary T cells express at least three different inducible DNA-binding proteins that specifically interact with this IL-2R{alpha} {kappa}B element.

Lowenthal, J.W.; Ballard, D.W.; Boehnlein, E.; Greene, W.C. (Duke Univ. Medical Center, Durham, NC (USA))

1989-04-01

228

III-V/Silicon Lattice-Matched Tandem Solar Cells  

SciTech Connect

A two-junction device consisting of a 1.7-eV GaNPAs junction on a 1.1-eV silicon junction has the theoretical potential to achieve nearly optimal efficiency for a two-junction tandem cell. We have demonstrated a monolithic III-V-on-silicon tandem solar cell in which most of the III-V layers are nearly lattice-matched to the silicon substrate. The cell includes a GaNPAs top cell, a GaP-based tunnel junction (TJ), and a diffused silicon junction formed during the epitaxial growth of GaNP on the silicon substrate. To accomplish this, we have developed techniques for the growth of high crystalline quality lattice-matched GaNPAs on silicon by metal-organic vapor-phase epitaxy.

Geisz, J.; Olson, J.; Friedman, D.; Kurtz, S.; McMahon, W.; Romero, M.; Reedy, R.; Jones, K.; Norman, A.; Duda, A.; Kibbler, A.; Kramer, C.; Young, M.

2005-01-01

229

Tandem MS can Distinguish Hyaluronic Acid from N-Acetylheparosan  

PubMed Central

Isobaric oligosaccharides enzymatically prepared from hyaluronic acid (HA) and N-acetylheparosan (NAH), were distinguished using tandem mass spectrometry. The only difference between the two series of oligosaccharides was the linkage pattern (in HA 1?3 and in NAH 1?4) between glucuronic acid and N-acetylglucosamine residues. Tandem mass spectrometry afforded spectra, in which glycosidic cleavage fragment ions were observed for both HA and NAH oligosaccharides. Cross-ring cleavage ions 0,2An and 0,2An-h (n is even number) were observed only in GlcNAc residues of NAH oligosaccharides. One exception was an 0,2A2 ion fragment observed for the disaccharide from HA. These cross-ring cleavage fragment ions are useful to definitively distinguish HA and NAH oligosaccharides.

Zhang, Zhenqing; Xie, Jin; Liu, Jian; Linhardt, Robert J.

2008-01-01

230

Evidence for rolling circle replication of tandem genes in Drosophila  

PubMed Central

Extrachromosomal circular DNA (eccDNA) is one characteristic of the plasticity of the eukaryotic genome. It is found in various organisms and contains sequences derived primarily from repetitive chromosomal DNA. Using 2D gel electrophoresis, we have previously detected eccDNA composed of chromosomal tandem repeats throughout the life cycle of Drosophila. Here, we report for the first time evidence suggesting the occurrence of rolling circle replication of eccDNA in Drosophila. We show, on 2D gels, specific structures that can be enriched by benzoylated naphthoylated DEAE-cellulose chromatography and were identified in other systems as rolling circle intermediates (RCIs). These RCIs are homologous to histone genes, Stellate and Suppressor of Stellate, which are all organized in the chromosomes as tandem repeats. RCIs are detected throughout the life cycle of Drosophila and in cultured fly cells. These structures are found regardless of the expression of the replicated gene or of its chromosomal copy number.

Cohen, Sarit; Agmon, Neta; Yacobi, Keren; Mislovati, Margarita; Segal, Daniel

2005-01-01

231

Single P-N junction tandem photovoltaic device  

DOEpatents

A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

Walukiewicz, Wladyslaw (Kensington, CA); Ager, III, Joel W. (Berkeley, CA); Yu, Kin Man (Lafayette, CA)

2011-10-18

232

Single P-N junction tandem photovoltaic device  

DOEpatents

A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

Walukiewicz, Wladyslaw (Kensington, CA); Ager, III, Joel W. (Berkeley, CA); Yu, Kin Man (Lafayette, CA)

2012-03-06

233

Statically scanned single and tandem low-coherence interferometers  

NASA Astrophysics Data System (ADS)

Statically scanned single and tandem Michelson interferometer configurations are compared for the remote measurement of thermally induced group delay change in optically dispersive glass samples. A broadband tungsten filament bulb was used to illuminate the single interferometer, and a much narrower spectral bandwidth superluminescent diode (SLD) was used to illuminate the tandem interferometer. For a BK7 glass sample, measurements of thermally induced group delay changes were made with <0.5 fs root mean square error for optical path delay (OPD) scan lengths of only 260 µm when applied to low-coherence interferograms with signal-to-noise ratios as low as 6.5 dB. These results demonstrate the power of dispersive Fourier transform spectrometry (DFTS) applied to noisy, dispersion distorted low-coherence interferograms captured with non-mechanical, short path length scans. Further, following experimentally observed source bandwidth-induced measurement resolution limitations between the different illuminating sources, simulations were performed to examine this feature.

Murphy, Dominic F.; Flavin, Dónal A.

2010-09-01

234

The TESS (Tandem Experiment Simulation Studies) computer code user's manual  

SciTech Connect

TESS (Tandem Experiment Simulation Studies) is a one-dimensional, bounded particle-in-cell (PIC) simulation code designed to investigate the confinement and transport of plasma in a magnetic mirror device, including tandem mirror configurations. Mirror plasmas may be modeled in a system which includes an applied magnetic field and/or a self-consistent or applied electrostatic potential. The PIC code TESS is similar to the PIC code DIPSI (Direct Implicit Plasma Surface Interactions) which is designed to study plasma transport to and interaction with a solid surface. The codes TESS and DIPSI are direct descendants of the PIC code ES1 that was created by A. B. Langdon. This document provides the user with a brief description of the methods used in the code and a tutorial on the use of the code. 10 refs., 2 tabs.

Procassini, R.J. (California Univ., Berkeley, CA (USA). Dept. of Nuclear Engineering); Cohen, B.I. (Lawrence Livermore National Lab., CA (USA))

1990-06-01

235

Bridge to Transplantation with the TandemHeart  

PubMed Central

Herein, we report a successful bridge to heart transplantation by use of the TandemHeart® percutaneous ventricular assist device (pVAD) in a chronic aortic dissection patient who was experiencing postcardiotomy shock. The patient had undergone an aortocoronary bypass to treat an acute, extensive myocardial infarction that had resulted from severe stenosis of a Cabrol-like graft to the left main coronary artery. The TandemHeart was used successfully, despite classic contraindications for pVAD support. The outcome shows that, in critically ill cardiogenic shock patients, a permissive approach to pVAD use is valuable in screening candidates for long-term ventricular assist device support or for heart transplantation. This case also reveals the validity of direct bridging to transplantation from a pVAD in carefully selected patients.

Reverdin, Stephane; Gregoric, Igor D.; Kar, Biswajit; Loyalka, Pranav; Bieniarz, Mark C.; LeMaire, Scott A.; Coselli, Joseph S.; Frazier, O. H.

2008-01-01

236

Reflectance modulator based on tandem Fabry-Perot resonators  

SciTech Connect

We present calculations and data on a novel, electrically tunable reflector structure consisting of tandem Fabry--Perot resonators grown as a single epitaxial device. The device consists of three mirrors (quarter-wave stacks of AlGaAs and AlAs) separated by two cavities (one an AlGaAs alloy and the other a GaAs/AlGaAs superlattice) on a GaAs substrate. The tandem cavities produce a characteristic double-dipped reflectance spectrum which can be modulated by tunable electro-optic effects in the superlattice cavity. Our demonstration device has a modulation depth of {gt}10% over a 20 nm bandwidth with {lt}4 V of bias swing.

Fritz, I.J.; Klem, J.F.; Wendt, J.R. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (US))

1991-08-12

237

New bulb turbine with counter-rotating tandem-runner  

NASA Astrophysics Data System (ADS)

With the increasing demand for the clean sustainable power, the turbine design urgently turns to increase the capability significantly toward higher head for generating larger power. Currently, there are many studies in the field of the bulb turbine with single-stage runner, though reports about counter-rotating tandem-runner are rare. However, the further high-head application with the single-stage runner is very difficult to achieve due to the limit of the specific speed. In this paper, a new bulb turbine with the tandem-runner is designed in order to substantially increase the applicable limit toward higher head with larger power. A half of the net head is absorbed by the frontal runner which can generate output power, while the remaining half is absorbed by the rear runner. To generate the Euler energy required for the rear runner, the frontal runner has the counter-rotation against the rear runner so that the counter-rotating tandem-runner can meet the purpose of double head and power under the same size as the conventional bulb turbine. Supply and demand of Euler energy between the two runners are thoroughly optimized through the detailed flow analysis, in order to secure the stable operation. As a result, the interference of Euler energies between the outflow from the frontal runner and the inflow to the rear runner is confirmed to be very small on the counter-rotating interface between the two runners. The prediction method of on-cam performance between the two adjustable runners is also developed numerically, which provides optimal flow between the two runners. This research provides a theoretical basis for the optimal design and operation of the counter-rotating tandem-runner bulb turbines.

Han, Fengqin; Yang, Lijing; Yan, Shijie; Kuboat, Takashi

2012-09-01

238

Automatic Quality Assessment of Peptide Tandem Mass Spectra  

Microsoft Academic Search

Motivation: A powerful proteomics methodology couples high-performance liquid chromatography (HPLC) with tandem mass spectrometry and database-search software, such as SEQUEST. Such a set-up, however, produces a large num- ber of spectra, many of which are of too poor quality to be useful. Hence a filter that eliminates poor spectra before the database search can significantly improve throughput and robustness. Moreover,

Marshall W. Bern; David Goldberg; W. Hayes Mcdonald; John R. Yates III

2004-01-01

239

Tandem Fourier transform mass spectrometry of large molecules  

Microsoft Academic Search

Fourier-transform mass spectrometry has a number of key advantages, including simultaneous ion detection over a wide mass range, ultra-high resolution, and extensive capabilities for tandem mass spectrometry (MS\\/MS, even MSⁿ). Here, new methods for soft ionization including ²⁵²Cf plasma desorption, 193 nm laser desorption, multiphoton ionization, and electrospray ionization (ESI) are demonstrated to produce abundant molecular ion species from a

1990-01-01

240

InGaN\\/Si heterojunction tandem solar cells  

Microsoft Academic Search

Tandem solar cells using InxGa1-xN heterojunctions with silicon as the active junction were fabricated using gas-source molecular beam epitaxy (MBE) and by a novel deposition method incorporating an energetic nitrogen atom source. N-type InGaN layers were grown on p-Si(111) to evaluate predicted low-resistance tunnel junction properties. Ohmic behavior was observed, showing that these junctions can be used to connect the

J. W. Ager; L. A. Reichertz; K. M. Yu; W. J. Schaff; T. L. Williamson; M. A. Hoffbauer; N. M. Haegel; W. Walukiewicz

2008-01-01

241

Charge exchange cooling in the tandem mirror plasma confinement apparatus  

DOEpatents

Method and apparatus for cooling a plasma of warm charged species confined in the center mirror cell of the tandem mirror apparatus by injecting cold neutral species of the plasma into at least one mirroring region of the center mirror cell, the cooling due to the loss of warm charged species through charge exchange with the cold neutral species with resulting diffusion of the warm neutral species out of the plasma.

Logan, B. Grant (Danville, CA)

1978-01-01

242

Sputtered II-VI Alloys and Structures for Tandem PV  

Microsoft Academic Search

This project focuses primarily on the development and optimization of two II-VI alloy materials for top cells (CdMnTe and CdMgTe) and HgCdTe for bottom cells of tandem PV devices. These are being explored both in two-terminal and four-terminal configurations. Spectroscopic ellipsometry is being developed for real- time analysis and deposition control. Parallel effort addresses the development and optimization of transparent

A. D. Compaan; R. W. Collins; V. Parikh; X. Mathew; D. Giolando; S. X. Marsillac; Anuja Parikh; Jie Chen; Jian Li

243

Free Radical-Induced Tandem Base Damage in DNA Oligomers  

Microsoft Academic Search

A new tandem base lesion has been identified in two DNA oligomers, namely d(GpT) and d(CpGpTpA), exposed to X-irradiation in deoxygenated aqueous solution. In this lesion the C6 carbon atom of thymine is hydroxylated and a covalent link is formed between the C5 carbon atom of thymine and the C8 carbon atom of the adjacent guanine base. In addition, further

Harold C Box; Edwin E Budzinski; Jean B Dawidzik; Jason S Gobey; Harold G Freund

1997-01-01

244

Isotope effects in a multicusp tandem ion source  

SciTech Connect

Measurements of plasma parameters, including electron density, electron energy distribution function (eedf), and negative ion density, have been made in the driver and extractor regions of a multicusp tandem ion source. Here results which focus on comparing operation in hydrogen and deuterium are presented. Several isotope effects are evident. In particular, for the same operating conditions, the electron density is found to be higher in deuterium than in hydrogen while the negative ion density is consistently lower.

Graham, W.G. (Department of Pure and Applied Physics, Queen's University, Belfast BT7 1NN (Northern Ireland))

1992-10-05

245

Asymmetric tandem Michael addition-Wittig reaction to cyclohexenone annulation.  

PubMed

A highly stereoselective tandem Michael addition-Wittig reaction of (3-carboxy-2-oxopropylidene)triphenylphosphorane and alpha,beta-unsaturated aldehydes has been developed by employing the combined catalysis of a newly designed bulky chiral secondary amine 1g, LiClO(4), and DABCO. The multifunctional 6-carboxycyclohex-2-en-1-ones were generally obtained in excellent diastereo- and enantioselectivities (dr up to >50:1, 86-99% ee). PMID:19518069

Liu, Yan-kai; Ma, Chao; Jiang, Kun; Liu, Tian-Yu; Chen, Ying-Chun

2009-07-01

246

Tandem Riboswitch Architectures Exhibit Complex Gene Control Functions  

Microsoft Academic Search

Riboswitches are structured RNAs typically located in the 5' untranslated regions of bacterial mRNAs that bind metabolites and control gene expression. Most riboswitches sense one metabolite and function as simple genetic switches. However, we found that the 5' region of the Bacillus clausii metE messenger RNA includes two riboswitches that respond to S-adenosylmethionine and coenzyme B12. This tandem arrangement yields

Narasimhan Sudarsan; Ming C. Hammond; Kirsten F. Block; Rüdiger Welz; Jeffrey E. Barrick; Adam Roth; Ronald R. Breaker

2006-01-01

247

Efficiency limits for single-junction and tandem solar cells  

Microsoft Academic Search

Basic limitations of single-junction and tandem p–n and p–i–n diodes are established from thermodynamical considerations on radiative recombination and semi-empirical considerations on the classical diode equations. These limits are compared to actual values of short-circuit current, open-circuit voltage, fill factor and efficiency for amorphous (a-Si:H) and microcrystalline (?c-Si:H) silicon solar cells. For single-junction cells, major efficiency gains should be achievable

F. Meillaud; A. Shah; C. Droz; E. Vallat-Sauvain; C. Miazza

2006-01-01

248

TMX-U Tandem-Mirror thermal-barrier experiments  

SciTech Connect

Thermal-barrier experiments have been carried out in the Tandem Mirror Experiment-Upgrade (TMX-U). Measurements of nonambipolar and ambipolar radial transport show that these transport processes, as well as end losses, can be controlled at modest densities and durations. Central-cell heating methods using ion-cyclotron heating (ICH) and neutral-beam injection have been demonstrated. Potential measurements with recently developed methods indicate that deep thermal barriers can be established.

Simonen, T.C.; Allen, S.L.; Baldwin, D.E.; Barter, J.D.; Berzins, L.V.; Carter, M.R.; Casper, T.A.; Clauser, J.F.; Coensgen, F.H.; Correll, D.L.

1986-10-29

249

Comparative end-plug study for tandem-mirror reactors  

NASA Astrophysics Data System (ADS)

A comparative evaluation was made of several end plug configurations for tandem mirror fusion reactors with thermal barriers. The axicell configuration has been selected for further study and will be the basis for a detailed conceptual design study to be carried out over the next two years. The axicell end plug has a simple mirror cell produced by two circular coils followed by a transition coil and a yin-yang pair, which provides for MHD stability.

Carlson, G. A.; Barr, W. L.; Boghosian, B. M.; Devoto, R. S.; Doggett, J. N.; Hamilton, G. W.; Johnston, B. M.; Kumai, W. N.; Lee, J. D.; Logan, B. G.

1981-12-01

250

Sulphur hexafluoride as a stripper gas for tandem accelerators  

NASA Astrophysics Data System (ADS)

Sulphur hexafluoride is investigated as a stripper gas in tandem accelerators.For heavy ions at low terminal voltage, mean charge states are found to be up to 1 charge unit higher than with argon gas.Charge state distributions are found to be broader than with argon gas.For charge states above the mean charge state, yields are typically doubled using SF6.Using SF6 stripper gas, the efficiency of actinides AMS analysis is doubled.

Hotchkis, M. A. C.; Child, D.; Fink, D.; Garton, D.; Levchenko, V.; Wilcken, K.

2013-05-01

251

Multilocus variable number tandem repeat analysis for Salmonella enterica subspecies  

Microsoft Academic Search

Genomic analysis of Salmonella enterica revealed the existence of a variable number of tandem repeats (VNTR) at multiple loci. Some S. enterica strains are considered as references (Typhi Ty2, Typhi CT18, Typhimurium LT2, Enteritidis LK5, PT4, and Enteritidis 07-2642,\\u000a and Newport). These allowed the selection of markers to develop the genotyping technique, multiple-locus VNTR analysis (MLVA).\\u000a These markers were used

S. L. Kruy; H. van Cuyck; J. L. Koeck

2011-01-01

252

Population genetics of short tandem repeat (STR) loci  

Microsoft Academic Search

To investigate the population genetics of short tandem repeat (STR) polymorphisms in human populations, we have studied the allele frequency distributions of four STR loci (HUMTH01, HUMVWA31, HUMF13A1 and HUMFES) in 16 different population surveys which can be categorised within three broadly defined ethnic groups: Caucasian, Asian (Indian subcontinent), and African (Afro-Caribbean and US black). We have observed that allele

Peter Gill; Ian Evett

1995-01-01

253

Self-Passivating hybrid (organic\\/inorganic) tandem solar cell  

Microsoft Academic Search

A tandem photovoltaic device structure, consisting of a PbSe nanocrystal film and a P3HT\\/PCBM bulk heterojunction film, was fabricated. The PbSe film (top layer) serves as a photocurrent generator as well as a UV protector for the underlying polymer cell. The P3HT\\/PCBM photovoltaic cell (bottom layer) provides the necessary electric field to the top photoconducting layer to extract the photogenerated

Sung Jin Kim; Won Jin Kim; Alexander N. Cartwright; Paras N. Prasad

2009-01-01

254

Tandem active layer superluminescent diode with a very wide spectrum  

NASA Astrophysics Data System (ADS)

Broader spectral width superluminescent diodes having a new structure of tandem active layers are proposed and fabricated at a 1.3-micron wavelength. The emission spectral widths were successfully broadened over 100 nm, thus achieving a very short coherence length of less than 10 microns. Applying this new active layer structure to a Fabry-Perot cavity, a unique function of superluminescent/laser mode switching is also demonstrated.

Noguchi, Yoshio; Yasaka, Hiroshi; Mikami, Osamu

1991-05-01

255

Tandem Stop Codons in Ciliates That Reassign Stop Codons  

Microsoft Academic Search

Tandem stop codons are extra stop codons hypothesized to be present downstream of genes to act as a backup in case of read-through\\u000a of the real stop codon. Although seemingly absent from Escherichia coli, recent studies have confirmed the presence of such codons in yeast. In this paper we will analyze the genomes of two ciliate\\u000a species—Paramecium tetraurelia and Tetrahymena

Marie Adachi; Andre R. O. Cavalcanti

2009-01-01

256

Evolution of the Fusion Power Demonstration tandem mirror reactor configuration  

SciTech Connect

This paper gives a presentation of the evolution of configurations proposed for tandem mirror Fusion Power Demonstration (FPD) machines. The FPD study was undertaken to scope the mission as well as the technical and design requirements of the next tandem mirror device. Three configurations, entitled FPD I, II, and III were studied. During this process new systems were conceived and integrated into the design, resulting in a significantly changed overall machine configuration. The machine can be divided into two areas. A new center cell configuration, minimizing magnetic field ripple and thus maximizing center cell fusion power, features a semicontinuous solenoid. A new end cell has evolved which maintains the required thermal barrier in a significantly reduced axial length. The reduced end cell effective length leads to a shorter central cell length being required to obtain minimum ignition conditions. Introduced is the concept of an electron mantle stabilized octopole arrangement. The engineering features of the new end cell and maintenance concepts developed are influenced to a great extent by the octopole-based design. The new ideas introduced during the FPD study have brought forth a new perspective of the size, design, and maintenance of tandem mirror reactors, making them more attractive as commercial power sources.

O'Toole, J.A.; Lousteau, D.C.

1985-07-01

257

Evolution of the fusion power demonstration tandem mirror reactor configuration  

SciTech Connect

This paper gives a presentation of the evolution of configurations proposed for tandem mirror Fusion Power Demonstration (FPD) machines. The FPD study was undertaken to scope the mission as well as the technical and design requirements of the next tandem mirror device. Three configurations, entitled FPD I, II, and III were studied. During this process new systems were conceived and integrated into the design, resulting in a significantly changed overall machine configuration. The machine can be divided into two areas. A new center cell configuration, minimizing magnetic field ripple and thus maximizing center cell fusion power, features a semicontinuous solenoid. A new end cell has evolved which maintains the required thermal barrier in a significantly reduced axial length. The reduced end cell effective length leads to a shorter central cell length being required to obtain minimum ignition conditions. Introduced is the concept of an electron mantle stabilized octopole arrangement. The engineering features of the new end cell and maintenance concepts developed are influenced to a great extent by the octopole-based design. The new ideas introduced during the FPD study have brought forth a new perspective of the size, design, and maintenance of tandem mirror reactors, making them more attractive as commercial power sources.

O'Toole, J.A.; Lousteau, D.C.

1985-01-01

258

Building and Searching Tandem Mass Spectral Libraries for Peptide Identification*  

PubMed Central

Spectral library searching is an emerging approach in peptide identifications from tandem mass spectra, a critical step in proteomic data analysis. Conceptually, the premise of this approach is that the tandem MS fragmentation pattern of a peptide under some fixed conditions is a reproducible fingerprint of that peptide, such that unknown spectra acquired under the same conditions can be identified by spectral matching. In actual practice, a spectral library is first meticulously compiled from a large collection of previously observed and identified tandem MS spectra, usually obtained from shotgun proteomics experiments of complex mixtures. Then, a query spectrum is then identified by spectral matching using recently developed spectral search engines. This review discusses the basic principles of the two pillars of this approach: spectral library construction, and spectral library searching. An overview of the software tools available for these two tasks, as well as a high-level description of the underlying algorithms, will be given. Finally, several new methods that utilize spectral libraries for peptide identification in ways other than straightforward spectral matching will also be described.

Lam, Henry

2011-01-01

259

Preliminary design of a Tandem-Mirror-Next-Step facility  

NASA Astrophysics Data System (ADS)

The Tandem-Mirror-Next-Step (TMNS) facility is designed to demonstrate the engineering feasibility of a tandem-mirror reactor. The facility is based on a deuterium-tritium (D-T) burning, tandem-mirror device with a fusion power output of 245 MW. The fusion power density in the central cell is 2.1 MW/m(3), with a resultant neutron wall loading of 0.5 MW/m(2). Overall machine length is 116 m, and the effective central-cell length is 50.9 m. The magnet system includes end cells with yin-yang magnets to provide magnetohydrodynamic (MHD) stability and thermal-barrier cells to help achieve a plasma Q of 4.7 (where Q = fusion power/injected power). Neutral beams at energies up to 200 keV are used for plasma heating, fueling, and barrier pumping. Electron cyclotron resonant heating at 50 and 100 GHz is used to control the electron temperature in the barriers. Based on the resulting engineering design, the overall cost of the facility is estimated to be just under $1 billion. Unresolved physics issues include central-cell beta-limits against MHD ballooning modes (the assumed reference value of beta exceeds the current theory derived limit), and the removal of thermalized alpha-particles from the plasma.

Damm, C. C.; Doggett, J. N.; Bulmer, R. H.; Neef, W. S.; Hamilton, G. W.; Sherwood, A. E.; Szybalski, S.; Boghosian, B. M.; Carlson, G. A.; Moir, R. W.

1980-12-01

260

The ORNL 25 MV tandem accelerator control system  

NASA Astrophysics Data System (ADS)

The CAMAC-based control system for the 25 MV tandem electrostatic accelerator of the Holifield Heavy Ion Research Facility at Oak Ridge National Laboratory (ORNL) was specified by ORNL and built by the National Electrostatics Corporation. Two Perkin-Elmer 32-bit minicomputers are used in the system: a message switching computer and a supervisory computer. The message switching computer transmits and receives control information on six serial highways. This computer shares memory with the supervisory computer. Operator consoles are located on a serial highway; control is by means of a console CRT, trackball, and assignable shaft encoders and meters. Two identical consoles operate simultaneously: one is located in the tandem control room; the other is located in the cyclotron control room to facilitate operation during injection of tandem beams into the cyclotron or when beam lines under control of the cyclotron control system are used. The supervisory computer is used for accelerator parameter setup calculations, actual accelerator setup for new beams based on scaled, recorded parameters from previously run beams, and various other functions. The experience of nearly seven years of control system operation and improvements is discussed. Co-op student, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.

Juras, Raymond C.; Biggerstaff, John A.; Hoglund, David E.

1986-06-01

261

Use of amorphous silicon tandem junction solar cells for hydrogen production in a photoelectrochemical cell  

NASA Astrophysics Data System (ADS)

We report the use of amorphous silicon (a-Si) tandem junctions as part of an integral "hybrid" photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight. The device configuration consists of stainless steel (SS)/ni2pni1p/ZnO/WO3. When the device is immersed in an electrolyte and illuminated, O2 is evolved at the WO3/electrolyte interface and H2 is produced at the counter electrode. A voltage >1.23V is required to split water; typically 1.6-1.8V are needed, taking account of losses in a practical water-splitting system. We use a-Si tandem cells, deposited by plasma-enhanced chemical vapor deposition, to supply this voltage. Current matching in the two a-Si subcells is achieved by altering the thicknesses of the two layers (i1 and i2) while keeping their band gaps at ~1.75eV, which results in a device with an open circuit voltage >1.6V, short circuit current density (Jsc) >6mA/cm2 (on SS substrates), and a fill factor >0.6. Deposition on a textured SnO2 coated glass has resulted in Jsc >9mA/cm2. Photoactive WO3 films, deposited using the RF sputtering technique, have achieved photocurrents >3mA/cm2 at 1.6V vs. saturated calomel electrode (SCE). The PEC device operates at the point at which the WO3 photocurrent IV curve and the a-Si (filtered by WO3) light IV curve cross, leading to operating currents of 2.5mA/cm2 and solar-to-hydrogen (STH) conversion efficiency of >3%.

Stavrides, Alex; Kunrath, Augusto; Hu, Jian; Treglio, Richard; Feldman, Ari; Marsen, Bjorn; Cole, Brian; Miller, Eric; Madan, Arun

2006-09-01

262

Moral Enhancement  

PubMed Central

Opponents of biomedical enhancement often claim that, even if such enhancement would benefit the enhanced, it would harm others. But this objection looks unpersuasive when the enhancement in question is a moral enhancement — an enhancement that will expectably leave the enhanced person with morally better motives than she had previously. In this article I (1) describe one type of psychological alteration that would plausibly qualify as a moral enhancement, (2) argue that we will, in the medium-term future, probably be able to induce such alterations via biomedical intervention, and (3) defend future engagement in such moral enhancements against possible objections. My aim is to present this kind of moral enhancement as a counter-example to the view that biomedical enhancement is always morally impermissible.

Douglas, Thomas

2008-01-01

263

Collision-induced dissociation of corticosteroids in electrospray tandem mass spectrometry and development of a screening method by high performance liquid chromatography/tandem mass spectrometry.  

PubMed

A screening method based on liquid chromatography/electrospray tandem mass spectrometry was developed in order to control the illegal use of corticosteroids as growth promoters in cattle. The objective was the detection of low residue levels of corticosteroids or metabolites in biological matrices. Relative to other studies published on this subject, the present work focused on enhancing specificity and sensitivity. Firstly, fragmentation of corticosteroids by collision-induced dissociation was studied. In positive mode, the losses of H(2)O for each hydroxyl group fixed on the molecule, as well as the loss of HF or HCl for halogenated compounds, were observed. For higher collision energy, fragmentations in the B, C and D rings were induced. The negative mode was found to be more specific, inducing a cleavage of the C(20)-C(21) bond with concomitant loss of formaldehyde (CH(2)O). Secondly, three acquisition methods in the negative mode were studied and evaluated, recorded signals being the parent ion [M + acetate](-) and the two daughter ions, [M - H](-) and [M - H - CH(2)O](-). For dexamethasone, MS/MS instrumental detection limits of fragment ion and neutral loss scans, and of multiple reaction monitoring (MRM), were 250, 20 and 5 pg injected, respectively. The MRM method was then evaluated with the objective of use for the detection of corticosteroid residues in biological samples (urine, hair, muscle) and for a metabolism study. PMID:10623925

Antignac, J P; Le Bizec, B; Monteau, F; Poulain, F; André, F

2000-01-01

264

Drift wave stability and transport in tandem mirrors  

NASA Astrophysics Data System (ADS)

In recent years experimental advances at the GAMMA-10 facility in Tsukuba, Japan have shown that tandem mirrors should remain an important subject for theoretical study. The absence of toroidal curvature and relatively weak internal plasma parallel currents in a tandem mirror gives the mirror system strongly favorable stability and transport properties compared with toroidal systems. GAMMA-10 experiments (T. Cho et al. PRL (97), 2006) demonstrate that sheared plasma rotation suppresses turbulent radial losses by controlling radial potential profiles. Achievements of the GAMMA-10 include 2.5 keV ion confining potentials and electron temperatures approaching 1 keV (T. Cho, Private correspondence, Dec 24th, 2006). Total energy confinement times for the GAMMA-10 experiment are significantly larger than corresponding empirical confinement times in toroidal devices. At the temperatures currently achieved in the GAMMA-10, the end loss rate tau?? ? 100 ms so that radial losses determine the energy confinement time tauE, as intended in tandem mirror reactor designs (R. F. Post, T.K. Fowler, et al., Fusion Science and Technology, (47), 2005). The most current measurements of tauE are on the order of 72 ms. Tandem mirrors exhibit a qualitatively different type of drift wave transport than do toroidal devices, as we have shown by developing confinement time scaling predictions (J. Pratt and W. Horton, Phys. Plasmas (13), 2006. W. Horton, J. Pratt, H.L. Berk, M. Hirata. Proceedings of the Open Magnetic Systems For Plasma Confinement Conference. Tsukuba, Japan, July 17-21, 2006). These predictions use a variety of standard transport models, e.g., Bohm, gyro-Bohm, and electron-temperature gradient models. We analyze electrostatic drift wave eigenmodes for the electrostatic potential and the magnetic perturbation in the GAMMA-10. We use teraFLOPS speed, large scale parallel computers to integrate the orbits in models of the drift wave losses in the GAMMA-10. We extrapolate these results to reactor designs for the kinetically stabilized tandem mirror reactor proposed by Post et al., and discuss implications for its stability, transport, and performance.

Pratt, Jane Lillian

265

Multiple-locus variable-number tandem repeat analysis of Salmonella Enteritidis isolates from human and non-human sources using a single multiplex PCR  

PubMed Central

Simplified multiple-locus variable-number tandem repeat analysis (MLVA) was developed using one-shot multiplex PCR for seven variable-number tandem repeats (VNTR) markers with high diversity capacity. MLVA, phage typing, and PFGE methods were applied on 34 diverse Salmonella Enteritidis isolates from human and non-human sources. MLVA detected allelic variations that helped to classify the S. Enteritidis isolates into more evenly distributed subtypes than other methods. MLVA-based S. Enteritidis clonal groups were largely associated with sources of the isolates. Nei's diversity indices for polymorphism ranged from 0.25 to 0.70 for seven VNTR loci markers. Based on Simpson's and Shannon's diversity indices, MLVA had a higher discriminatory power than pulsed field gel electrophoresis (PFGE), phage typing, or multilocus enzyme electrophoresis. Therefore, MLVA may be used along with PFGE to enhance the effectiveness of the molecular epidemiologic investigation of S. Enteritidis infections.

Cho, Seongbeom; Boxrud, David J; Bartkus, Joanne M; Whittam, Thomas S; Saeed, Mahdi

2007-01-01

266

Simultaneous determination of eight corticosteroids in bovine tissues using liquid chromatography-tandem mass spectrometry.  

PubMed

This paper describes a newly developed method for the simultaneous determination of eight corticosteroid residues in bovine muscle, liver and kidney samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The determination of methylprednisone, the main metabolite of methylprednisolone, in bovine tissues using LC-MS/MS is carried out for the first time. The method development demonstrates that the pH is important in optimizing the sample preparation. Tests performed using different solid-phase extraction (SPE) cartridges were enabled to produce conditions for reducing the matrix effects (ion suppression and enhancement) of analysis. Acidic condition and mixed-mode cation exchange SPE columns resulted in the most suitable clean-up for muscle and liver, and also yielded acceptable results for kidney. The enhanced sample clean-up resulted in excellent clear baselines of ion transitions, and therefore, a higher delta electron multiplier voltage (?EMV) could be set in the MS/MS detector. The application of 500 V of ?EMV improved the signal responses, however, the noise level did not change, and consequently, the overall sensitivity and analytical limits (limit of detection, limit of quantification) could be enhanced. In the HPLC separation, the recently introduced Kinetex phenyl-hexyl core-shell type column was used that enabled baseline separation for dexamethasone and its ?-epimer, betamethasone. Dexamethasone and betamethasone were eluted within 12 min and such reduced retention, obtained with core-shell HPLC type column, further enhanced the sensitivity. The method was validated according to the European Union (EU) 2002/657/EC Decision; the studied parameters met the EU standards. The decision limits and limit of detections were calculated in each matrix for all corticosteroids and varied from 0.01 to 13.3?g/kg and from 0.01 to 0. 1 ?g/kg, respectively. PMID:22981346

Tölgyesi, Adám; Sharma, Virender K; Fekete, Szabolcs; Lukonics, Dóra; Fekete, Jen?

2012-09-01

267

High-efficiency radiation-resistant InGaP\\/GaAs tandem solar cells  

Microsoft Academic Search

A world-record efficiency of 26.9% (AMO, 28°C) has been obtained for InGaP\\/GaAs tandem solar cells fabricated by the MOCVD method. The radiation resistance of the InGaP\\/GaAs tandem solar cells has also been evaluated following 1 MeV electron irradiation. Degradation in tandem cell performance has been confirmed to be mainly attributed to large degradation in the GaAs bottom cell, which features

T. Takamoto; M. Yamaguchi; S. J. Taylor; E. Ikeka; T. Agui; H. Kurita

1997-01-01

268

Tandem Aldol Condensation - Platinacycle-Catalyzed Addition Reactions of Aldehydes, Methyl Ketones and Arylboronic Acids  

PubMed Central

Tandem aldol condensation of aldehydes with methyl ketones followed by anionic four-electron donor-based (Type I) platinacycle-catalyzed addition reactions of arylboronic acids to form ?-arylated ketones is described. Good to excellent yields of ?-arylated ketones were obtained for the tandem reactions of aromatic/aliphatic aldehydes, methyl ketones and arylboronic acids, and moderate yields were observed for the tandem reaction with ?, ?-unsaturated aldehydes as the aldehyde source.

Liao, Yuan-Xi; Hu, Qiao-Sheng

2013-01-01

269

Tandem Aldol Condensation - Platinacycle-Catalyzed Addition Reactions of Aldehydes, Methyl Ketones and Arylboronic Acids.  

PubMed

Tandem aldol condensation of aldehydes with methyl ketones followed by anionic four-electron donor-based (Type I) platinacycle-catalyzed addition reactions of arylboronic acids to form ?-arylated ketones is described. Good to excellent yields of ?-arylated ketones were obtained for the tandem reactions of aromatic/aliphatic aldehydes, methyl ketones and arylboronic acids, and moderate yields were observed for the tandem reaction with ?, ?-unsaturated aldehydes as the aldehyde source. PMID:23335856

Liao, Yuan-Xi; Hu, Qiao-Sheng

2012-09-01

270

Preprocessing of Tandem Mass Spectrometric Data Based on Decision Tree Classification  

Microsoft Academic Search

In this study, we present a preprocessing method for quadrupole time-of-flight (Q-TOF) tandem mass spectra to increase the accuracy of database searching for peptide (protein) identification. Based on the natural isotopic information inher- ent in tandem mass spectra, we construct a decision tree after feature selection to classify the noise and ion peaks in tandem spectra. Furthermore, we recognize overlapping

Jing-Fen Zhang; Si-Min He; Jin-Jin Cai; Xing-Jun Cao; Rui-Xiang Sun; Yan Fu; Rong Zeng; Wen Gao

2005-01-01

271

Evolution of Tandemly Repeated Sequences: What Happens at the End of an Array?  

Microsoft Academic Search

.   Tandemly repeated sequences are a major component of the eukaryotic genome. Although the general characteristics of tandem\\u000a repeats have been well documented, the processes involved in their origin and maintenance remain unknown. In this study, a\\u000a region on the paternal sex ratio (PSR) chromosome was analyzed to investigate the mechanisms of tandem repeat evolution. The\\u000a region contains a junction

Bryant F. McAllister; John H. Werren

1999-01-01

272

Structural features and ligand binding properties of tandem WW domains from YAP and TAZ, nuclear effectors of the Hippo pathway.  

PubMed

The paralogous multifunctional adaptor proteins YAP and TAZ are the nuclear effectors of the Hippo pathway, a central mechanism of organ size control and stem cell self-renewal. WW domains, mediators of protein-protein interactions, are essential for YAP and TAZ function, enabling interactions with PPxY motifs of numerous partner proteins. YAP has single and double WW domain isoforms (YAP1 and YAP2) whereas only a single WW domain isoform of TAZ has been described to date. Here we identify the first example of a double WW domain isoform of TAZ. Using NMR, we have characterized conformational features and peptide binding of YAP and TAZ tandem WW domains (WW1-WW2). The solution structure of YAP WW2 confirms that it has a canonical three-stranded antiparallel ?-sheet WW domain fold. While chemical shift-based analysis indicates that the WW domains in the tandem WW pairs retain the characteristic WW domain fold, 15N relaxation data show that, within the respective WW pairs, YAP WW1 and both WW1 and WW2 of TAZ undergo conformational exchange. 15N relaxation data also indicate that the linker between the WW domains is flexible in both YAP and TAZ. Within both YAP and TAZ tandem WW pairs, WW1 and WW2 bind single PPxY-containing peptide ligand concurrently and noncooperatively with sub-mM affinity. YAP and TAZ WW1-WW2 bind a dual PPxY-containing peptide with approximately 6-fold higher affinity. Our results indicate that both WW domains in YAP and TAZ are functional and capable of enhanced affinity binding to multi-PPxY partner proteins such as LATS1, ErbB4, and AMOT. PMID:21417403

Webb, Claire; Upadhyay, Abhishek; Giuntini, Francesca; Eggleston, Ian; Furutani-Seiki, Makoto; Ishima, Rieko; Bagby, Stefan

2011-03-31

273

Interpretation of tandem mass spectra obtained from cyclic nonribosomal peptides.  

PubMed

Natural and non-natural cyclic peptides are a crucial component in drug discovery programs because of their considerable pharmaceutical properties. Cyclosporin, microcystins, and nodularins are all notable pharmacologically important cyclic peptides. Because these biologically active peptides are often biosynthesized nonribosomally, they often contain nonstandard amino acids, thus increasing the complexity of the resulting tandem mass spectrometry data. In addition, because of the cyclic nature, the fragmentation patterns of many of these peptides showed much higher complexity when compared to related counterparts. Therefore, at the present time it is still difficult to annotate cyclic peptides MS/MS spectra. In this current work, an annotation program was developed for the annotation and characterization of tandem mass spectra obtained from cyclic peptides. This program, which we call MS-CPA is available as a web tool (http://lol.ucsd.edu/ms-cpa_v1/Input.py). Using this program, we have successfully annotated the sequence of representative cyclic peptides, such as seglitide, tyrothricin, desmethoxymajusculamide C, dudawalamide A, and cyclomarins, in a rapid manner and also were able to provide the first-pass structure evidence of a newly discovered natural product based on predicted sequence. This compound is not available in sufficient quantities for structural elucidation by other means such as NMR. In addition to the development of this cyclic annotation program, it was observed that some cyclic peptides fragmented in unexpected ways resulting in the scrambling of sequences. In summary, MS-CPA not only provides a platform for rapid confirmation and annotation of tandem mass spectrometry data obtained with cyclic peptides but also enables quantitative analysis of the ion intensities. This program facilitates cyclic peptide analysis, sequencing, and also acts as a useful tool to investigate the uncommon fragmentation phenomena of cyclic peptides and aids the characterization of newly discovered cyclic peptides encountered in drug discovery programs. PMID:19413302

Liu, Wei-Ting; Ng, Julio; Meluzzi, Dario; Bandeira, Nuno; Gutierrez, Marcelino; Simmons, Thomas L; Schultz, Andrew W; Linington, Roger G; Moore, Bradley S; Gerwick, William H; Pevzner, Pavel A; Dorrestein, Pieter C

2009-06-01

274

A tandem non-aldol aldol Mukaiyama aldol reaction.  

PubMed

[reaction: see text] A new one-pot tandem aldol process is described in which a secondary epoxy silyl ether is converted into the 1,5-bis-silyloxy-3-alkanone in good yield. Thus, treatment of the epoxy silyl ether 8 with TBSOTf and base affords the silyl enol ether 9 via non-aldol aldol rearrangement and addition of benzaldehyde and TBSOTf gives the ketone 10 with 4:1 syn selectivity. The diastereoselectivity changes to an anti preference for most aldehydes. This anti selectivity overwhelms the normal Felkin-Ahn preference; namely, the 1,5-anti isomer predominates even when it is anti-Felkin-Ahn. PMID:14627420

Jung, Michael E; van den Heuvel, Alexandra

2003-11-27

275

Neutron induced reactions at the Athens Tandem Accelerator NCSR “Demokritos”  

Microsoft Academic Search

The neutron facility at the 5.5 MV tandem T11\\/25 Accelerator of NCSR “Demokritos” can deliver monoenergetic neutron beams\\u000a in the energy range from thermal to 450 keV, 4–11.5 MeV and 16–20.5 MeV via the 7Li(p,n), 2H(d,n) and 3H(d,n) reactions, respectively. The flux variation of the neutron beam is monitored by using a BF3 counter and a liquid scintillator BC501A detector.

R. Vlastou; C. T. Papadopoulos; M. Kokkoris; G. Perdikakis; S. Galanopoulos; M. Serris; A. Lagoyannis; S. Harissopulos

2007-01-01

276

Search for the optimal linker in tandem hairpin polyamides.  

PubMed

In order to target specific DNA sequences >or=10 base pairs in size by minor groove binding ligands, a search for the optimal linker in dimers of hairpin polyamides was initiated. Two series of tandem polyamides ImPyIm-(R)[ImPyIm-(R)(H2N)gamma-PyPyPy-L](HN)gamma-PyPyPy-beta-Dp (1a-e), where L represents a series of 4-8 carbon long aliphatic amino acid linkers, and ImPyIm-(R)[ImPyIm-(R)(H2N)gamma-PyPyPyIm-L](HN)gamma-PyPyPy-beta-Dp (2a-e), where L represents a series of 2-6 carbon long aliphatic amino acid linkers, were synthesized and characterized by quantitative DNase I footprinting. beta, gamma and Dp represents beta-alanine, gamma-aminobutyric acid, and 3-(dimethylamino)propylamine, respectively. It was found that the five-carbon 5-aminovaleric acid (delta), is suitable to span one base-pair (bp) of DNA when incorporated into a tandem polyamide. ImPyIm-(R)[ImPyIm-(R)(H2N)gamma-PyPyPy-delta](HN)gamma-PyPyPy-beta-Dp (1b) binds the 10 bp binding-site 5'-AGTGAAGTGA-3' with equilibrium association constant K(a)=3.2 x 10(10) M(-1) and ImPyIm-(R)[ImPyIm-(R)(H2N)gamma-PyPyPyIm-delta](HN)gamma-PyPyPy-beta-Dp (2d) binds the 11 bp binding-site 5'-AGTGATAGTGA-3' with K(a)=9.7 x 10(9) M(-1). Tandem 1b also bind the 11 bp site but with lower affinity affording a 15-fold specificity for the shorter binding site. Replacing a methylene group in the amino acid linker with an oxygen atom to form tandem polyamide ImPyIm-(R)[ImPyIm-(R)(H2N)gamma-PyPyPy-E](HN)gamma-PyPyPy-beta-Dp (4) where E represents the ether linker, resulted in that an 80-fold specificity for the 10 bp binding site over the 11 bp site. PMID:12150881

Kers, Inger; Dervan, Peter B

2002-10-01

277

Tandem synthesis of alternating polyesters from renewable resources  

PubMed Central

The vast majority of commodity materials are obtained from petrochemical feedstocks. These resources will plausibly be depleted within the next 100 years, and the peak in global oil production is estimated to occur within the next few decades. In this regard, biomass represents an abundant carbon-neutral renewable resource for the production of polymers. Here we report a new strategy, based on tandem catalysis, to obtain renewable materials. Commercially available complexes are found to be efficient catalysts for alternating polyesters from the cyclization of dicarboxylic acids followed by alternating copolymerization of the resulting anhydrides with epoxides. This operationally simple method is an attractive strategy for the production of new biodegradable polyesters.

Robert, Carine; de Montigny, Frederic; Thomas, Christophe M.

2011-01-01

278

[Variable tandem repeat VcA of Vibrio cholerae].  

PubMed

Computer analysis revealed seven potential variable-number tandem-repeat (VNTR) loci in the Vibrio cholerae genome. Specific primers were designed to amplify locus VcA located on chromosome 2 and containing a TGCTGT repeat. The locus was found in all tested strains from a V. cholerae strain collection, the repeat number varying 3 to 23. In total, 14 VcA alleles were observed. The VcA locus was proposed as a marker for the molecular typing of V. cholerae strains. PMID:12500547

Vodop'ianov, S O; Ole?nikov, I P; Goncharov, E K; Duvanova, O V; Mishan'kin, M B; Suchkov, I Iu; Vodop'ianov, A S; Shishiianu, M V; Shcherbakova, E V; Kornienko, I V; Mishan'kin, B N

279

Analysis of Short Tandem Repeats by Parallel DNA Threading  

PubMed Central

The majority of studies employing short tandem repeats (STRs) require investigation of several of these genetic markers. As such, we demonstrate the feasibility of the trinucleotide threading (TnT) approach for scalable analysis of STRs. The TnT method represents a parallel amplification alternative that addresses the obstacles associated with multiplex PCR. In this study, analysis of the STR fragments was performed with capillary gel electrophoresis; however, it should be possible to combine our approach with the massive 454 sequencing platform to considerably increase the number of targeted STRs.

Zajac, Pawel; Oberg, Christine; Ahmadian, Afshin

2009-01-01

280

Development of large band-gap conjugated copolymers for efficient regular single and tandem organic solar cells.  

PubMed

We demonstrated the synthesis and characterization of two conjugated copolymers, PBDTFBZO and PBDTFBZS, consisting of dialkylthiol substituted benzo[1,2-b:4,5-b']dithiophene donor and monofluorinated benzotriazole acceptor blocks. The resulting copolymers show large band gaps, deep HOMO and LUMO energy levels. Improved Voc, Jsc, and FF were obtained at the same time to increase overall efficiencies of their single and tandem polymer solar cells. The enhanced Voc can be ascribed to a low-lying HOMO energy level by incorporating dialkylthiol and fluorine substituents on the polymer backbone. The improvement in Jsc and FF are likely due to high carrier mobility, suppressed charge recombination, and fine nanostructure morphology. A 7.74% PCE was achieved from the regular single device based on PBDTFBZS:PC71BM blend film with 3% 1,8-diiodooctane (DIO) additive. In combination with low band gap diketopyrrolopyrrole (DPP)-based copolymer, tandem devices based on PBDTFBZS exhibited high PCE up to 9.40%. The results indicate that PBDTFBZO and PBDTFBZS are promising polymer donor materials for future application of large-area polymer solar cells. PMID:23962272

Li, Kai; Li, Zuojia; Feng, Kui; Xu, Xiaopeng; Wang, Lingyan; Peng, Qiang

2013-08-30

281

Transcription of clpP Is Enhanced by a Unique Tandem Repeat Sequence in Streptococcus mutans  

Microsoft Academic Search

Streptococcus mutans, the primary causative agent of human dental caries, contains a single copy of the gene encoding ClpP, the chief intracellular protease responsible for tolerance to various environmental stresses. To better understand the role of ClpP in stress response, we investigated the regulation of clpP expression in S. mutans. Using semiquantitative reverse transcription-PCR analysis, we observed that, under nonstressed

Jiaqin Zhang; Anirban Banerjee; Indranil Biswas

2009-01-01

282

Simulation of Two Dimensional Electrophoresis and Tandem Mass Spectrometry for Teaching Proteomics  

ERIC Educational Resources Information Center

|In proteomics, complex mixtures of proteins are separated (usually by chromatography or electrophoresis) and identified by mass spectrometry. We have created 2DE Tandem MS, a computer program designed for use in the biochemistry, proteomics, or bioinformatics classroom. It contains two simulations--2D electrophoresis and tandem mass spectrometry.…

Fisher, Amanda; Sekera, Emily; Payne, Jill; Craig, Paul

2012-01-01

283

Analyzing Forced Unfolding of Protein Tandems by Ordered Variates, 1: Independent Unfolding Times  

PubMed Central

Most of the mechanically active proteins are organized into tandems of identical repeats, (D)N, or heterogeneous tandems, D1–D2–…–DN. In current atomic force microscopy experiments, conformational transitions of protein tandems can be accessed by employing constant stretching force f (force-clamp) and by analyzing the recorded unfolding times of individual domains. Analysis of unfolding data for homogeneous tandems relies on the assumption that unfolding times are independent and identically distributed, and involves inference of the (parent) probability density of unfolding times from the histogram of the combined unfolding times. This procedure cannot be used to describe tandems characterized by interdomain interactions, or heteregoneous tandems. In this article, we introduce an alternative approach that is based on recognizing that the observed data are ordered, i.e., first, second, third, etc., unfolding times. The approach is exemplified through the analysis of unfolding times for a computer model of the homogeneous and heterogeneous tandems, subjected to constant force. We show that, in the experimentally accessible range of stretching forces, the independent and identically distributed assumption may not hold. Specifically, the uncorrelated unfolding transitions of individual domains at lower force may become correlated (dependent) at elevated force levels. The proposed formalism can be used in atomic force microscopy experiments to infer the unfolding time distributions of individual domains from experimental histograms of ordered unfolding times, and it can be extended to analyzing protein tandems that exhibit interdomain interactions.

Bura, E.; Klimov, D. K.; Barsegov, V.

2007-01-01

284

Combining percolator with X!Tandem for accurate and sensitive peptide identification.  

PubMed

In this work, Percolator was successfully interfaced with X!Tandem using a PHP program to generate an improved search platform, X!Tandem Percolator. In order to achieve the best classification performance of peptide identifications in Percolator, a set of experimentally validated spectral identifications (34,993 MS/MS spectra) were used to guide the development of discriminatory features from X!Tandem search results. By comparing the features (e.g., Log(E) and mass error) of these experimentally validated peptide matches with those of false identifications, a comprehensive set of features can be chosen for Percolator in an objective and rational manner. The accuracy of X!Tandem Percolator was demonstrated by comparing the estimated q-value of the validated data set with the empirical q-value. By comparing the results from the X!Tandem Percolator and the original X!Tandem, superior sensitivity and specificity of the X!Tandem Percolator result was demonstrated on various shotgun proteomic data sets under different search conditions. In all of the cases studied in this work, X!Tandem Percolator could improve the number of peptide identifications at the same level of q-values. PMID:23581882

Xu, Mingguo; Li, Zhendong; Li, Liang

2013-05-01

285

Comparative analysis of tandem repeats from hundreds of species reveals unique insights into centromere evolution  

Technology Transfer Automated Retrieval System (TEKTRAN)

Centromeres are essential for chromosome segregation, yet their DNA sequences evolve rapidly. In most animals and plants that have been studied, centromeres comprise of megabase-scale arrays of tandem repeats. The true prevalence of centromere tandem repeats, and whether they exhibit conserved seque...

286

Numerical analysis of the s1020 airfoils in tandem under different flapping configurations  

Microsoft Academic Search

The objective of this project is to improve the performance of the efficiency, thrust and lift of flapping wings in tandem arrangement. This research investigates the effect of the arrangement of the airfoils in tandem on the performance of the airfoils by varying the phase difference and distance between the airfoils. Three flapping configurations from an earlier phase of a

K. B. Lim; W. B. Tay

2010-01-01

287

Solution processed polymer tandem solar cell using efficient small and wide bandgap polymer:fullerene blends.  

PubMed

Solution processed polymer tandem solar cells that combine wide and small bandgap absorber layers reach a power conversion efficiency of 7% in a series configuration. This represents a 20% increase compared to the best single junction cells made with the individual active layers and shows that the tandem configuration reduces transmission and thermalization losses in converting sunlight. PMID:22438114

Gevaerts, Veronique S; Furlan, Alice; Wienk, Martijn M; Turbiez, Mathieu; Janssen, René A J

2012-03-21

288

Tandem GM Type-Pulse Tube Refrigerator with Novel Rotary Valve and Bypass Valve Mechanism  

Microsoft Academic Search

A single-stage tandem pulse tube refrigerator has been fabricated, which is driven by two pulsating pressures of opposite phase. The refrigerator is designed as the first stage machine of a 4 K pulse tube refrigerator using a recuperator as the second stage regenerator. In this tandem configuration, two pressure pulsations are generated by a single GM-cryocooler compressor. Two identical pulse

J. Jung; S. Jeong; Y. Kwon; M. Sohn

2006-01-01

289

A design for a tandem AGVS with multi-load AGVs  

Microsoft Academic Search

A tandem automated guided vehicle system (AGVS) is obtained by partitioning all workstations into multiple zones and assigning a single vehicle to each zone. In this paper, we propose an analytical model to design a tandem AGVS with multi-load AGVs. Using simulations, the performance of the proposed model is shown by comparing it with a conventional multi-load AGVS.

KyungSup Kim; ByungDo Chung; Moosung Jae

2003-01-01

290

An unsupervised machine learning method for assessing quality of tandem mass spectra  

PubMed Central

Background In a single proteomic project, tandem mass spectrometers can produce hundreds of millions of tandem mass spectra. However, majority of tandem mass spectra are of poor quality, it wastes time to search them for peptides. Therefore, the quality assessment (before database search) is very useful in the pipeline of protein identification via tandem mass spectra, especially on the reduction of searching time and the decrease of false identifications. Most existing methods for quality assessment are supervised machine learning methods based on a number of features which describe the quality of tandem mass spectra. These methods need the training datasets with knowing the quality of all spectra, which are usually unavailable for the new datasets. Results This study proposes an unsupervised machine learning method for quality assessment of tandem mass spectra without any training dataset. This proposed method estimates the conditional probabilities of spectra being high quality from the quality assessments based on individual features. The probabilities are estimated through a constraint optimization problem. An efficient algorithm is developed to solve the constraint optimization problem and is proved to be convergent. Experimental results on two datasets illustrate that if we search only tandem spectra with the high quality determined by the proposed method, we can save about 56 % and 62% of database searching time while losing only a small amount of high-quality spectra. Conclusions Results indicate that the proposed method has a good performance for the quality assessment of tandem mass spectra and the way we estimate the conditional probabilities is effective.

2012-01-01

291

Comparative analysis of tandem repeats from hundreds of species reveals unique insights into centromere evolution.  

PubMed

BACKGROUND: Centromeres are essential for chromosome segregation, yet their DNA sequences evolve rapidly. In most animals and plants that have been studied, centromeres contain megabase-scale arrays of tandem repeats. Despite their importance, very little is known about the degree to which centromere tandem repeats share common properties between different species across different phyla. We used bioinformatic methods to identify high-copy tandem repeats from 282 species using publicly available genomic sequence and our own data. RESULTS: Our methods are compatible with all current sequencing technologies. Long Pacific Biosciences sequence reads allowed us to find tandem repeat monomers up to 1,419 bp. We assumed that the most abundant tandem repeat is the centromere DNA, which was true for most species whose centromeres have been previously characterized, suggesting this is a general property of genomes. High-copy centromere tandem repeats were found in almost all animal and plant genomes, but repeat monomers were highly variable in sequence composition and length. Furthermore, phylogenetic analysis of sequence homology showed little evidence of sequence conservation beyond approximately 50 million years of divergence. We find that despite an overall lack of sequence conservation, centromere tandem repeats from diverse species showed similar modes of evolution. CONCLUSIONS: While centromere position in most eukaryotes is epigenetically determined, our results indicate that tandem repeats are highly prevalent at centromeres of both animal and plant genomes. This suggests a functional role for such repeats, perhaps in promoting concerted evolution of centromere DNA across chromosomes. PMID:23363705

Melters, Daniël P; Bradnam, Keith R; Young, Hugh A; Telis, Natalie; May, Michael R; Ruby, J Graham; Sebra, Robert; Peluso, Paul; Eid, John; Rank, David; Garcia, José Fernando; Derisi, Joseph L; Smith, Timothy; Tobias, Christian; Ross-Ibarra, Jeffrey; Korf, Ian; Chan, Simon Wl

2013-01-30

292

Tandem Repeat Stability in Escherichia coli O157:H7 is Dependent on Environmental Stress  

Technology Transfer Automated Retrieval System (TEKTRAN)

Multilocus variable number tandem repeat analysis (MLVA) is used for source tracking Escherichia coli O157:H7 in agricultural environments. Tandem repeats were stable after limited replication, but changed after irradiation, elevated temperatures and starvation conditions. Plasmid, pO157, was lost ...

293

Comparative analysis of tandem repeats from hundreds of species reveals unique insights into centromere evolution  

Technology Transfer Automated Retrieval System (TEKTRAN)

Centromeres are essential for chromosome segregation, yet their DNA sequences evolve rapidly. In most animals and plants that have been studied, centromeres contain megabase-scale arrays of tandem repeats. Despite their importance, very little is known about the degree to which centromere tandem r...

294

Cavitation and Open-Water Performance of a Set of Tandem Propellers.  

National Technical Information Service (NTIS)

Cavitation tunnel and open-water results are presented for a set of tandem propellers at various angular spacings between blades and axial spacings between propellers. The open water results show that the tandem propeller operated at 3.5 percent higher ef...

R. D. Kader

1974-01-01

295

A tandem Aldol-Grob reaction of ketones with aromatic aldehydes  

Microsoft Academic Search

Aromatic aldehydes react with ketones to produce(E)-1-aryl-1-alkenes via a tandem Aldol-Grob cleavage reaction sequence. The reaction, initiated by boron trifluoride, also produces a carboxylic acid fragment.Aromatic aldehydes react with ketones in the presence of boron trifluoride to produce(E)-1-aryl-1-alkenes via a tandem Aldol-Grob cleavage reaction sequence.

George W. Kabalka; David Tejedor; Nan-Sheng Li; Rama R. Malladi; Sarah Trotman

1998-01-01

296

Characterization of a tandemly repeated DNA from the fleshfly Sarcophaga bullata  

Microsoft Academic Search

In studies on the highly repetitive DNA sequences of the flesh flySarcophaga bullata, a 279 bp tandem repeat was cloned and sequenced. A 17 bp stretch within the clone was identical to a motif repeated five times in the satellite DNA of the Bermuda land crab. Southern DNA blotting showed the tandem repeat had a high degree of conservation of

Bennett Hershfield; Hewson Swift

1990-01-01

297

White organic light-emitting diodes based on tandem structures  

NASA Astrophysics Data System (ADS)

White organic light-emitting diodes made of two electroluminescent (EL) units connected by a charge generation layer were fabricated. Thus, with a tandem structure of indium tin oxide/N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB)/9,10-bis-(?-naphthyl)-anthrene (ADN)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminum (Alq3)/BCP:Li/V2O5/NPB/Alq3:4-(dicyanomethylene)-2-t-butyle-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB)/Alq3/LiF/Al, a stable white light with Commission Internationale De L'Eclairage chromaticity coordinates from (0.35, 0.32) at 18 V to (0.36, 0.36) at 50 V was generated. It was clearly seen that the EL spectra consist of red band at 600 nm due to DCJTB, green band at 505 nm due to Alq3, and blue band at 435 nm due to ADN, and the current efficiency and brightness equal basically to the sum of the two EL units. As a result, the tandem devices showed white light emission with a maximum brightness of 10 200 cd/m2 at a bias of 40 V and a maximum current efficiency of 10.7 cd/A at a current density of 3.5 mA/cm2.

Guo, Fawen; Ma, Dongge

2005-10-01

298

An unprecedented, tandem Aldol-Grob reaction sequence  

SciTech Connect

The authors report an unprecedented, tandem Aldol-Grob sequence involving the reaction of ketones with aromatic aldehydes in nonnucleophilic solvents in the presence of boron trifluoride. Although a detailed study of the reaction mechanism has not yet been completed, the consistent formation of (E)-alkene products, as well as the fact that aromatic aldehydes appear to be required, would point toward the intermediacy of a carbocation derivative. A reasonable mechanism would involve the formation of the mixed aldol followed by the formation and subsequent nonsynchronous ring opening of a lactol. The proposed fragmentation is reminiscent of two-step Grob fragmentations that have been reported for N-halo-{alpha}-amino acids and cyclobutane hemiacetals as well as the acid-catalyzed fragmentation of {beta}-hydroxy acetals. The authors examined the effect of various acids on the reaction sequence in order to ascertain which would be most efficient. They conclude that boron trifluoride is the most effective of the acids studied in achieving the new tandem condensation-cleavage sequence.

Kabalka, G.W.; Tejedor, D.; Li, N.S.; Malladi, R.R.; Trotman, S. [Univ. of Tennessee, Knoxville, TN (United States)

1998-09-18

299

Numerous Length Polymorphisms at Short Tandem Repeats in Human Cytomegalovirus  

PubMed Central

We show the presence of numerous short tandem repeats in the human cytomegalovirus (HCMV) genome and assess their usefulness as molecular markers. The genome is shown to contain at least 24 microsatellite regions that exhibit length polymorphisms. Insertion-deletion polymorphisms at these short tandem repeats are common (80% of repeats examined are polymorphic among two laboratory strains and 10 clinical isolates). This is the first report of widespread microsatellite length polymorphism in a viral genome. Some regions are highly polymorphic: one was revealed by DNA sequencing to contain length variants at five closely linked sites, which combined resulted in 10 variants for this region among the 12 strains and isolates examined. This study not only provides a new molecular marker system for this virus but also extends our understanding of microsatellite polymorphism in two important ways. First, variable-length repeats in HCMV can be considerably shorter than polymorphic repeats previously found in other organisms. Second, highly variable microsatellite repeats are not confined to prokaryotes and eukaryotes, as previously assumed. This variation provides a useful marker system for distinguishing viral isolates, and similar markers are also likely to be found in other large-genome DNA viruses.

Davis, Clara L.; Field, Dawn; Metzgar, David; Saiz, Robert; Morin, Phillip A.; Smith, Irene L.; Spector, Stephen A.; Wills, Christopher

1999-01-01

300

Identification of polymorphic tandem repeats by direct comparison of genome sequence from different bacterial strains : a web-based resource  

Microsoft Academic Search

BACKGROUND: Polymorphic tandem repeat typing is a new generic technology which has been proved to be very efficient for bacterial pathogens such as B. anthracis, M. tuberculosis, P. aeruginosa, L. pneumophila, Y. pestis. The previously developed tandem repeats database takes advantage of the release of genome sequence data for a growing number of bacteria to facilitate the identification of tandem

Gilles Vergnaud

2004-01-01

301

76 FR 40935 - Vertical Tandem Lifts in Marine Terminals; Extension of the Office of Management and Budget's...  

Federal Register 2010, 2011, 2012, 2013

...OSHA-2011-0066] Vertical Tandem Lifts in Marine Terminals; Extension of the...contained in the Standard on Vertical Tandem Lifts (VTLs) in Marine Terminals (29 CFR part...contained in the Standard on Vertical Tandem Lifts for Marine Terminals (29 CFR part...

2011-07-12

302

Determination of raloxifene in urine by liquid chromatography-tandem mass spectrometry for doping.  

PubMed

Raloxifene is one of the selective estrogen receptor modulators and is often used to prevent and treat osteoporosis in postmenopausal women. Because of the indirect impact on serum testosterone levels and the potential ability for performance enhancement, it is banned by the World Anti-Doping Agency (WADA). This study established a fast, sensitive and selective liquid chromatography-tandem mass spectrometry method to quantify total raloxifene (unchanged and glucuronidated) in human urine for doping analysis. Urines from six healthy volunteers were collected 240 h after taking a single dose of raloxifene. The concentrations of urinary raloxifene were analyzed by the established method after sample preparation, including hydrolysis with ?-glucuronidase. The lowest limit of quantification was 0.5 ng/mL. Linearity was observed for raloxifene concentrations ranging from 0.5 to 100 ng/mL, with a correlation coefficient of 0.999. The recoveries were >92.81%. Inaccuracies were below ±5%, and precisions varied from 2.18 to 5.37%. The results showed that urinary raloxifene was immediately detectable within 4 h after the administration of only a single dose of raloxifene. Such a result indicates a violation of the WADA rules. Furthermore, ingesting raloxifene would be detectable after 6 days in the urine of males or >10 days in the urine of female. PMID:23772059

Chen, Ting-Ting; Huang, Tai-Yuan; Pan, Ryh-Nan; Chang-Chien, Guo-Ping; Hsu, Mei-Chich

2013-06-14

303

Simultaneous profiling of polar lipids by supercritical fluid chromatography/tandem mass spectrometry with methylation.  

PubMed

Supercritical fluid chromatography/tandem mass spectrometry (SFC/MS/MS) with methylation was used for the simultaneous profiling of diverse polar lipids in a mixture. A high throughput, high resolution analysis of nineteen classes of polar lipids including phospholipids, lysophospholipids, and sphingolipids was performed in 6 min. Methylation by trimethylsilyl-diazomethane suppressed peak tailing and improved detection sensitivity of phosphatidylserine (PS), phosphatidic acid (PA), lysophosphatidylserine (LPS), lysophosphatidylinositol (LPI), lysophosphatidic acid (LPA), ceramide-1-phosphate (Cer1P), sphingosine-1-phosphate (So1P), and sphinganine-1-phosphate (Sa1P). The limits of detection for PS, PA, LPS, LPI, LPA, Cer1P, So1P, and Sa1P were enhanced 7.5-, 26.7-, 600-, 116.7-, 500-, 75-, 3000-, and 4500-fold, respectively. Global qualitative and quantitative analysis of not only the high-abundance species but also the low-abundance species in the polar lipids was achieved. When the method was applied to mouse liver, 4 PSs, 24 PAs, 3 lysophosphatidylethanolamines, 11 LPSs, 6 lysophosphatidylglycerols, 4 LPIs, 13 LPAs, 7 sphingomyelins, 11 Cer1Ps, So1P, and Sa1P were additionally analyzed. Furthermore, the quantification of various molecular species in each polar lipid was carried out. PMID:23380365

Lee, Jae Won; Nishiumi, Shin; Yoshida, Masaru; Fukusaki, Eiichiro; Bamba, Takeshi

2013-01-10

304

End cell I and C requirements for operating tandem mirror reactors  

SciTech Connect

The next generation of fusion reactors will be developed to achieve near-ignition conditions and operate in a tritium environment for significant periods of time. Radiation-hardened diagnostic instrumentation must be developed for these reactors. Although neutral beam injection (NBI) will be used for plasma heating and fueling of experimental fusion machines like MFTF-..cap alpha.. + T, it is believed that ion cyclotron resonance heating (ICRH) will be used in future machines for heating the plasma. When rf heating is used, fueling will be accomplished with gas puffing and advanced fuel injectors. End cell coils, NBI, and microwave power injectors are needed to provide adequate confinement. Microwave power and NBI control the electostatic potentials of the plug and barrier. Low-frequency rf power provides drift pump control of the ions so that they are lost radially, enhancing the use of direct converters that collect the axially flowing electrons. Direct or indirect measurements of electrostatic potential barriers, electron density, and temperature appear necessary to control the NBI and microwave power generators. This paper discusses some of the end cell instrumentation and control (I and C) systems believed to be necessary for tandem mirror reactors.

Gorker, G.E.; Osher, J.E.

1983-01-01

305

Graph-based modeling of tandem repeats improves global multiple sequence alignment  

PubMed Central

Tandem repeats (TRs) are often present in proteins with crucial functions, responsible for resistance, pathogenicity and associated with infectious or neurodegenerative diseases. This motivates numerous studies of TRs and their evolution, requiring accurate multiple sequence alignment. TRs may be lost or inserted at any position of a TR region by replication slippage or recombination, but current methods assume fixed unit boundaries, and yet are of high complexity. We present a new global graph-based alignment method that does not restrict TR unit indels by unit boundaries. TR indels are modeled separately and penalized using the phylogeny-aware alignment algorithm. This ensures enhanced accuracy of reconstructed alignments, disentangling TRs and measuring indel events and rates in a biologically meaningful way. Our method detects not only duplication events but also all changes in TR regions owing to recombination, strand slippage and other events inserting or deleting TR units. We evaluate our method by simulation incorporating TR evolution, by either sampling TRs from a profile hidden Markov model or by mimicking strand slippage with duplications. The new method is illustrated on a family of type III effectors, a pathogenicity determinant in agriculturally important bacteria Ralstonia solanacearum. We show that TR indel rate variation contributes to the diversification of this protein family.

Szalkowski, Adam M.; Anisimova, Maria

2013-01-01

306

Graph-based modeling of tandem repeats improves global multiple sequence alignment.  

PubMed

Tandem repeats (TRs) are often present in proteins with crucial functions, responsible for resistance, pathogenicity and associated with infectious or neurodegenerative diseases. This motivates numerous studies of TRs and their evolution, requiring accurate multiple sequence alignment. TRs may be lost or inserted at any position of a TR region by replication slippage or recombination, but current methods assume fixed unit boundaries, and yet are of high complexity. We present a new global graph-based alignment method that does not restrict TR unit indels by unit boundaries. TR indels are modeled separately and penalized using the phylogeny-aware alignment algorithm. This ensures enhanced accuracy of reconstructed alignments, disentangling TRs and measuring indel events and rates in a biologically meaningful way. Our method detects not only duplication events but also all changes in TR regions owing to recombination, strand slippage and other events inserting or deleting TR units. We evaluate our method by simulation incorporating TR evolution, by either sampling TRs from a profile hidden Markov model or by mimicking strand slippage with duplications. The new method is illustrated on a family of type III effectors, a pathogenicity determinant in agriculturally important bacteria Ralstonia solanacearum. We show that TR indel rate variation contributes to the diversification of this protein family. PMID:23877246

Szalkowski, Adam M; Anisimova, Maria

2013-07-22

307

Tracing isolates of bacterial species by multilocus variable number of tandem repeat analysis (MLVA).  

PubMed

All bacterial genomes contain multiple loci of repetitive DNA. Repeat unit sizes and repeat sequences may vary when multiple loci are considered for different isolates of an individual microbial species. Moreover, it has been documented on many occasions that the number of repeat units per locus is a strain-defining parameter. Consequently, there is isolate-specificity in the number of repeats per locus when different strains of a given bacterial species are compared. The experimental assessment of this variability for a number of different loci has been called 'multilocus variable number of tandem repeat analysis' (MLVA). The approach can be supported or extended by locus-specific DNA sequencing for establishing mutations in the individual repeat units, which usually enhances the resolution of the approach considerably. Essentially, MLVA with or without supportive sequencing has been developed for all of the medically relevant bacterial species and can be used effectively for tracing outbreaks or other forms of bacterial dissemination. MLVA is a modern, timely and versatile bacterial typing methodology. PMID:17266711

van Belkum, Alex

2007-02-01

308

Single and tandem Fabry-Perot etalons as solar background filters for lidar.  

PubMed

Atmospheric lidar is difficult in daylight because of sunlight scattered into the receiver field of view. In this research methods for the design and performance analysis of Fabry-Perot etalons as solar background filters are presented. The factor by which the signal to background ratio is enhanced is defined as a measure of the performance of the etalon as a filter. Equations for evaluating this parameter are presented for single-, double-, and triple-etalon filter systems. The role of reflective coupling between etalons is examined and shown to substantially reduce the contributions of the second and third etalons to the filter performance. Attenuators placed between the etalons can improve the filter performance, at modest cost to the signal transmittance. The principal parameter governing the performance of the etalon filters is the etalon defect finesse. Practical limitations on etalon plate smoothness and parallelism cause the defect finesse to be relatively low, especially in the ultraviolet, and this sets upper limits to the capability of tandem etalon filters to suppress the solar background at tolerable cost to the signal. PMID:18324100

McKay, J A

1999-09-20

309

Liquid chromatography-atmospheric pressure photoionization tandem mass spectrometry for analysis of 36 halogenated flame retardants in fish.  

PubMed

A comprehensive, sensitive and high-throughput liquid chromatography-atmospheric pressure photoionization tandem mass spectrometry (LC-APPI-MS/MS) method has been developed for analysis of 36 halogenated flame retardants (HFRs). Under the optimized LC conditions, all of the HFRs eluted from the LC column within 14min, while maintaining good chromatographic separation for the isomers. Introduction of the pre-heated dopant to the APPI source decreased the background noise fivefold, which enhanced sensitivity. An empirical equation was proposed to describe the relation between the ion intensity and dopant flow. The excellent on-column instrument detection limits averaged 4.7pg, which was similar to the sensitivity offered by gas chromatography-high-resolution mass spectrometry (GC-HRMS). This method was used to analyze a series of fish samples. Good agreement was found between the results for PBDEs from LC-APPI-MS/MS and GC-HRMS. PMID:20022329

Zhou, Simon Ningsun; Reiner, Eric J; Marvin, Chris; Kolic, Terry; Riddell, Nicole; Helm, Paul; Dorman, Frank; Misselwitz, Michelle; Brindle, Ian D

2009-12-05

310

Electric transport in 3D photonic crystal intermediate reflectors for micromorph thin-film tandem solar cells  

NASA Astrophysics Data System (ADS)

The progress of 3D photonic intermediate reflectors for micromorph silicon tandem cells towards a first prototype cell is presented. Intermediate reflectors enhance the absorption of spectrally-selected light in the top cell and decrease the current mismatch between both junctions. A numerical method to predict filter properties for optimal current matching is presented. Our device is an inverted opal structure made of ZnO and fabricated using self-organized nanoparticles and atomic layer deposition for conformal coating. In particular, the influence of ZnO-doping and replicated cracks during drying of the opal is discussed with respect to conductivity and optical properties. A first prototype is compared to a state-of-the-art reference cell.

Üpping, J.; Bielawny, A.; Lee, S.; Knez, M.; Carius, R.; Wehrspohn, R. B.

2009-08-01

311

Mass spectrometry and tandem mass spectrometry of citrus limonoids.  

PubMed

Methods for atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) of citrus limonoid aglycones and electrospray ionization tandem mass spectrometry (ESI-MS/MS) of limonoid glucosides are reported. The fragmentation patterns of four citrus limonoid aglycones (limonin, nomilin, obacunone, and deacetylnomilin) and six limonoid glucosides, that is, limonin 17-beta-D-glucopyranoside (LG), nomilin 17-beta-D-glucopyranoside (NG), nomilinic acid 17-beta-D-glucopyranoside (NAG), deacetyl nomilinic acid 17-beta-D-glucopyranoside (DNAG), obacunone 17-beta-D-glucopyranoside (OG), and obacunoic acid 17-beta-D-glucopyranoside (OAG) were investigated using a quadruple mass spectrometer in low-energy collisionally activated dissociation (CAD). The four limonoid aglycones and four limonoid glucosides (LG, OG, NAG, and DNAG) were purified from citrus seeds; the other two limonoid glucosides (NG and OAG) were tentatively identified in the crude extract of grapefruit seeds by ESI mass spectrometry in both positive and negative ion analysis. Ammonium hydroxide or acetic acid was added to the mobile phase to facilitate ionization. During positive ion APCI analysis of limonoid aglycones, protonated molecular ion, [M + H]+, or adduct ion, [M + NH3 + H]-, was formed as base peaks when ammonium hydroxide was added to the mobile phase. Molecular anions or adduct ions with acetic acid ([M + HOAc - H] and [M + HOAc]-) or a deprotonated molecular ion were produced during negative ion APCI analysis of limonoid aglycones, depending on the mobile-phase modifier used. Positive ion ESI-MS of limonoid glucosides produced adduct ions of [M + H + NH3]+, [M + Na]+, and [M + K]+ when ammonium hydroxide was added to the mobile phase. After collisionally activated dissociation (CAD) of the limonoid aglycone molecular ions in negative ion APCI analysis, fragment ions indicated structural information of the precursor ions, showing the presence of methyl, carboxyl, and oxygenated ring structure. CAD of the adduct ion [M + H + NH3]+ of limonoid glucosides produced the aglycone moiety corresponding to each glucoside. The combination of mass spectrometry and tandem mass spectrometry provides a powerful technique for identification and characterization of citrus limonoids. PMID:14710824

Tian, Qingguo; Schwartz, Steven J

2003-10-15

312

Israeli tandem FEL: first-lasing results and future plans  

NASA Astrophysics Data System (ADS)

Results of first operation of the Israeli Electrostatic- Accelerator Tandem Free-Electron Laser (EA-FEL) are reported. This EA-FEL utilizes a 1.4 Amp electron beam obtained from a parallel flow Pierce-type electron gun. The e-beam is transported through a resonator located inside a plane Halbach configuration wiggler, both located at the high voltage terminal of the van de graaf accelerator. The high voltage terminal is charge to a positive plates waveguide and two Talbot effect quasioptical reflectors. It exhibited a quality factor of Q approximately equals 30,000. Millimeter wave radiation pulses of 2 microsecond(s) ec duration were obtained at a frequency of 100.5 GHz, as predicted, at a power level above 1 kW.

Abramovich, A.; Arensburg, A.; Chairman, D.; Eichenbaum, A.; Draznin, M.; Gover, Abraham; Kleinman, H.; Merhasin, I.; Pinhasi, Yosef; Sokolowski, J. S.; Yakover, Y. M.; Cohen, Moshe; Levin, L. A.; Shahal, O.; Rosenberg, Avner; Schnitzer, Itzhak; Shiloh, J.

1997-10-01

313

Sequencing of Oligourea Foldamers by Tandem Mass Spectrometry  

NASA Astrophysics Data System (ADS)

This study is focused on sequence analysis of peptidomimetic helical oligoureas by means of tandem mass spectrometry, to build a basis for de novo sequencing for future high-throughput combinatorial library screening of oligourea foldamers. After the evaluation of MS/MS spectra obtained for model compounds with either MALDI or ESI sources, we found that the MALDI-TOF-TOF instrument gave more satisfactory results. MS/MS spectra of oligoureas generated by decay of singly charged precursor ions show major ion series corresponding to fragmentation across both CO-NH and N'H-CO urea bonds. Oligourea backbones fragment to produce a pattern of a, x, b, and y type fragment ions. De novo decoding of spectral information is facilitated by the occurrence of low mass reporter ions, representative of constitutive monomers, in an analogous manner to the use of immonium ions for peptide sequencing.

Bathany, Katell; Owens, Neil W.; Guichard, Gilles; Schmitter, Jean-Marie

2013-03-01

314

Configuration and layout of the tandem mirror Fusion Power Demonstrator  

SciTech Connect

Studies have been performed during the past year to determine the configuration of a tandem mirror Fusion Power Demonstrator (FPD) machine capable of producing 1750 MW of fusion power. The FPD is seen as the next logical step after the Mirror Fusion Test Facility-B (MFTF-B) toward operation of a power reactor. The design of the FPD machine allows a phased construction: Phase I, a hydrogen or deuterium checkout machine; Phase 2, a DT breakeven machine; Phase 3, development of the Phase 2 machine to provide net power and act as a reactor demonstrator. These phases are essential to the development of remote handling equipment and the design of components that will ultimately be remotely handled. Phasing also permits more modes funding early in the program with some costs committed only after reaching major milestones.

Clarkson, I.R.; Neef, W.S.

1983-11-30

315

Tandem mirror magnet system for the mirror fusion test facility  

SciTech Connect

The Tandem Mirror Fusion Test Facility (MFTF-B) will be a large magnetic fusion experimental facility containing 22 supercounducting magnets including solenoids and C-coils. State-of-the-art technology will be used extensively to complete this facility before 1985. Niobium titanium superconductor and stainless steel structural cases will be the principle materials of construction. Cooling will be pool boiling and thermosiphon flow of 4.5 K liquid helium. Combined weight of the magnets will be over 1500 tonnes and the stored energy will be over 1600 MJ. Magnetic field strength in some coils will be more than 8 T. Detail design of the magnet system will begin early 1981. Basic requirements and conceptual design are disclosed in this paper.

Bulmer, R.H.; Van Sant, J.H.

1980-10-14

316

A new control system for an old tandem  

SciTech Connect

In an effort to maintain the most flexible environment for accelerator-based atomic physics research at ORNL EN Tandem facility, a recirculating terminal stripper project has been in development. In the early stages of planning for this upgrade, the necessity for monitoring and control of various parameters in the accelerator terminal was considered. To provide proper flexibility and accuracy, telemetry via computer seemed to be the obvious route. Since the development of a robust system not prone to upset from sparks was necessary, a phased development approach was taken. This involves first converting the accelerator`s ground potential systems, then ion source ({similar_to}100 kV) systems that can be easily accessed by merely running down high voltage supplies, and finally terminal potential systems operating in high pressure gas at potentials over 7 MV. Progress to date, including hardware arrangement and software development, is discussed.

Jones, N.L.

1996-11-01

317

e60Fe measurements with an EN tandem accelerator  

NASA Astrophysics Data System (ADS)

The long-lived radionuclide e60Fe has been detected at the low energies of an EN tandem accelerator. At an energy of 60 MeV, the suppression of the stable isobar i60Ni is the main problem. Spraying hydrogen gas onto the ion source target and extracting the metal single hydrides the nickel contamination in the beam can be reduced more than 500 fold. In the gas ionization detector another five orders of magnitude of suppression are obtained. The resulting background e/Fe60Fe/Fe ratio of about 10-11 has enabled first measurements with the standard samples used earlier at Argonne National Laboratory. The results of the two facilities are in agreement.

Gartenmann, P.; Schnabel, C.; Suter, M.; Synal, H.-A.

1997-03-01

318

Physics issues in mirror and tandem mirror systems  

SciTech Connect

Over the years the study of the confinement of high temperature plasma in magnetic mirror systems has presented researchers with many unusual physics problems. Many of these issues are by now understood theoretically and documented experimentally. With the advent of the tandem mirror idea, some new issues have emerged and are now under intensive study. These include: (1) the generation and control of ambipolar confining potentials and their effect on axial confinement and, (2) the combined influence of nonaxisymmetric magnetic fields (used to ensure MHD stability) and electric magnetic particle drifts on radial transport. Physics considerations associated with these two categories of issues will be reviewed, including concepts for the control of radial transport, under study or proposed.

Post, R.F.

1984-06-15

319

Orbit averaged radial buildup code for tandem mirror geometry  

SciTech Connect

The radial Fokker-Planck (RFP) model of A. Futch was modified to treat plasma buildup in the tandem mirror plug and center cell with a self-consistent model (TOARBUC). Two major changes have been made to the original version of this code. First, the center cell is treated as having separate electron and ion confining potentials with the ion potential having the opposite sign of that in a conventional mirror. Second, a two-electron-temperature treatment derived by R. Cohen was included in the present model to allow the plug and center cell to have different T/sub e/'s as observed in the experiment. The following sections explain these changes in greater detail.

Campbell, M.; Futch, A.H.

1981-01-22

320

Calculation of density profiles in tandem mirrors fueled by pellets  

SciTech Connect

We have modified the LLNL radial transport code TMT to model reactor regime plasmas, fueled by pellets. The source profiles arising from pellet fueling are obtained from existing pellet ablation models. Because inward radial diffusion due to inverted profiles must compete with trapping of central cell ions in the transition region for tandem mirrors, pellets must penetrate fairly far into the plasma. In fact, based on our radial calculations, a pellet with a velocity of 10 km/sec cannot sustain the central flux tubes; a velocity more like 100 km/sec will be necessary. We also find that the central cell radial diffusion must exceed classical by about a factor of 100.

Campbell, R.B.; Gilmore, J.M.

1983-12-02

321

Tandem regioselective synthesis of tetrazoles and related heterocycles using iodine.  

PubMed

A one-pot, tandem process has been developed for the synthesis of a library of tetrazoles from aryl isothiocyanates. Condensation of aryl isothiocyanates with ammonia, and aryl amines (R-NH(2)) provided mono, 1,3-disubstituted symmetrical and unsymmetrical thioureas, which on desulfurization with molecular iodine (I(2)) led to formation of the corresponding heterocumulene (cyanamides or carbodiimides). The in situ generated heterocumulene on subsequent treatment with sodium azide at room temperature gave corresponding tetrazoles. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas was found to be correlated with the basicities (pK(a)'s) of the parent amines attached to the thiourea. Aryl-sec-alkyl unsymmetrical thioureas gave thioamido guanidino products rather than the 5-aminotetrazoles produced by HgCl(2) mediation of the reaction. Bis-thioureas derived from aryl isothiocyanates and hydrazine gave thiadiazoles exclusively. PMID:21431153

Yella, Ramesh; Khatun, Nilufa; Rout, Saroj Kumar; Patel, Bhisma K

2011-03-23

322

Short-tandem repeat analysis in seven Chinese regional populations.  

PubMed

In the present study, we investigated the application of 13 short tandem repeat (STR) loci (D13S317, D7S820, TH01, D16S539, CSFIPO, VWA, D8S1179, TPOX, FGA, D3S1358, D21S11, D18S51 and D5S818) routinely used in forensic analysis, for delineating population relationships among seven human populations representing the two major geographic groups, namely the southern and northern Chinese. The resulting single topology revealed pronounced geographic and population partitioning, consistent with the differences in geographic location, languages and eating habits. These findings suggest that forensic STR loci might be particularly powerful tools in providing the necessary fine resolution for reconstructing recent human evolutionary history. PMID:21637565

Song, Xing-Bo; Zhou, Yi; Ying, Bin-Wu; Wang, Lan-Lan; Li, Yi-Song; Liu, Jian-Feng; Bai, Xiao-Gang; Zhang, Lei; Lu, Xiao-Jun; Wang, Jun; Ye, Yuan-Xin

2010-12-01

323

Short-tandem repeat analysis in seven Chinese regional populations  

PubMed Central

In the present study, we investigated the application of 13 short tandem repeat (STR) loci (D13S317, D7S820, TH01, D16S539, CSFIPO, VWA, D8S1179, TPOX, FGA, D3S1358, D21S11, D18S51 and D5S818) routinely used in forensic analysis, for delineating population relationships among seven human populations representing the two major geographic groups, namely the southern and northern Chinese. The resulting single topology revealed pronounced geographic and population partitioning, consistent with the differences in geographic location, languages and eating habits. These findings suggest that forensic STR loci might be particularly powerful tools in providing the necessary fine resolution for reconstructing recent human evolutionary history.

2010-01-01

324

Propulsion research on the variable tandem mirror plasma rocket  

NASA Astrophysics Data System (ADS)

This report describes the progress made in the past two years as well as the overall picture of this research. In the past years, several-milestones have been achieved towards the realization of a practical space plasma thruster from the tandem mirror rocket experiment, i.e. the specific impulse, thrust, energy conversion efficiency, and mass flow-rate have been determined. The experiment operates at 9.4 kW of input power at an RF-to-plasma efficiency of 68%; The ion temperature is 172 eV (2,000,000 K) which gives an I(sub sp) of 12,852 s. The thrust is 76 mN (milli Newton) which is a high value for a low input power (9.4 kW) and very high I(sub sp), (12,852 s). The radiation loss was found to be very low. Most important, these results fall within our prediction.

Yang, T. F.; Chang-Diaz, F. R.

1994-02-01

325

Triply-ionized B2 molecules from a tandem accelerator  

NASA Astrophysics Data System (ADS)

Beams of 10B3+2, 11B23+, and 10B11B3+ ions have been observed to emerge from a tandem accelerator. B2- mo into the accelerator, and positive ions emerging from the machine were analyzed for mass per charge and total energy. For 10B11B, intensities of singly-, doubly-, and triply-charged molecules were measured as a function of N2 gas pressure in the accelerator terminal stripper canal. These intensities were found to exhibit the same qualitative behavior for all charge states, with the number of triply-charged molecules a factor of ~ 2 × 10-4 less than for the doubly-charged molecules. No quadruply-ionized molecules were seen. The observation of particles corresponding to the breakup products of the multiply-ionized molecules indicates that these species were decaying in flight, and are apparently metastable with lifetimes of ~ ?s. Comparisons are made between these observations and molecular orbital calculations.

Weathers, D. L.; McDaniel, F. D.; Matteson, S.; Duggan, J. L.; Anthony, J. M.; Douglas, M. A.

1991-05-01

326

Comparative Genomic and Transcriptomic Analysis of Tandemly and Segmentally Duplicated Genes in Rice  

PubMed Central

Tandem and segmental duplications significantly contribute to gene family expansion and genome evolution. Genome-wide identification of tandem and segmental genes has been analyzed before in several plant genomes. However, comparative studies in functional bias, expression divergence and their roles in species domestication are still lacking. We have carried out a genome-wide identification and comparative analysis of tandem and segmental genes in the rice genome. A total of 3,646 and 3,633 pairs of tandem and segmental genes, respectively, were identified in the genome. They made up around 30% of total annotated rice genes (excluding transposon-coding genes). Both tandem and segmental duplicates showed different physical locations and exhibited a biased subset of functions. These two types of duplicated genes were also under different functional constrains as shown by nonsynonymous substitutions per site (Ka) and synonymous substitutions per site (Ks) analysis. They are also differently regulated depending on the tissues and abiotic and biotic stresses based on transcriptomics data. The expression divergence might be related to promoter differentiation and DNA methylation status after tandem or segmental duplications. Both tandem and segmental duplications differ in their contribution to genetic novelty but evidence suggests that they play their role in species domestication and genome evolution.

Jiang, Shu-Ye; Gonzalez, Jose M.; Ramachandran, Srinivasan

2013-01-01

327

Genetic diversity in the Mycobacterium tuberculosis complex based on variable numbers of tandem DNA repeats.  

PubMed

Genetic loci containing variable numbers of tandem repeats (VNTR loci) form the basis for human gene mapping and identification, forensic analysis and paternity testing. The variability of bacterial tandem repeats has not been systematically studied. Eleven tandem repeat loci in the M. tuberculosis genome were analysed. Five major polymorphic tandem repeat (MPTR) loci contained 15-bp repeats with substantial sequence variation in adjacent copies. Six exact tandem repeat (ETR) loci contained large DNA repeats with identical sequences in adjacent repeats. These 11 loci were amplified in 48 strains to determine the number of tandem repeats at each locus. The strains analysed included 25 wild-type strains of M. tuberculosis, M. bovis, M. africanum and M. microti and 23 substrains of the attenuated M. bovis BCG vaccine. One of the five MPTR loci and all six ETR loci had length polymorphisms corresponding to insertions or deletions of tandem repeats. Most ETR loci were located in intergenic regions where copy number may influence expression of downstream genes. Each ETR locus had multiple alleles in the panel. Combined analysis identified 22 distinct allele profiles in 25 wild-type strains of the M. tuberculosis complex and five allele profiles in 23 M. bovis BCG substrains. Allele profiles were reproducible and stable, as demonstrated by analyses of multiple isolates of particular reference strains obtained from different laboratories. VNTR typing may be generally useful for strain differentiation and evolutionary studies in bacteria. PMID:9611793

Frothingham, R; Meeker-O'Connell, W A

1998-05-01

328

Study of Long-Distance Functional Interactions between Su(Hw) Insulators That Can Regulate Enhancer-Promoter Communication in Drosophila melanogaster  

Microsoft Academic Search

The Su(Hw) insulator found in the gypsy retrotransposon is the most potent enhancer blocker in Drosophila melanogaster. However, two such insulators in tandem do not prevent enhancer-promoter communication, apparently because of their pairing interaction that results in mutual neutralization. Furthering our studies of the role of insulators in the control of gene expression, here we present a functional analysis of

Ekaterina Savitskaya; Larisa Melnikova; Margarita Kostuchenko; Elena Kravchenko; Ekaterina Pomerantseva; Tatiana Boikova; Darya Chetverina; Aleksander Parshikov; Polyna Zobacheva; Elena Gracheva; Alexander Galkin; Pavel Georgiev

2006-01-01

329

Intermediate layers for tandem structure of bulk heterojunction photovoltaic cells  

NASA Astrophysics Data System (ADS)

For advanced organic thin film photovoltaic cell, stacked structure of single cells, tandem structure, would be a key issue. Many kinds of tandem structure have been already reported. When an appropriate intermediate layer was inserted between the single cells, open circuit voltage (Voc) can be doubled compared with the single cell. For small molecules, vacuum evaporation can be applicable for fabrication. Systematic investigations have been made to reveal the requirement for the intermediate materials. Quite thin, a few nm thick, metal layer can act as intermediate layer[1]. The metal cannot form continuous layer but island lake structure in such small amount. On the other hand, the combination of the metal oxide (such as ZnO, TiO2 and ITO) and PEDOT:PSS are used for the intermediate layer. We need to reveal minimum requirement for the intermediate materials for polymer based bulkhererojunction cells for low-cost high performance organic photovoltaic cells. We have developed a polymer thin film preparation technique, Evaporative Spray Deposition using Ultradilute Solution (ESDUS)[2]. This method has enabled fabricating organic thin films applicable to polymer light-emitting diodes, organic photovoltaics and organic field-effect transistors13 from highly diluted solutions of 1-10 ppm. Moreover, it has been exhibited that a successive polymer layer can be deposited without damaging the preceding polymer layer by use of a same solvent for each layer deposition. We conduct the systematic investigation of the intermediate materials. Onto the bottom cell/intermediate layer, top cell can be deposited by use of ESDUS.

Kawanami, Akito; Fujita, Katsuhiko

2012-09-01

330

Coding Tandem Repeats Generate Diversity in Aspergillus fumigatus Genes? †  

PubMed Central

Genes containing multiple coding mini- and microsatellite repeats are highly dynamic components of genomes. Frequent recombination events within these tandem repeats lead to changes in repeat numbers, which in turn alters the amino acid sequence of the corresponding protein. In bacteria and yeasts, the expansion of such coding repeats in cell wall proteins is associated with alterations in immunogenicity, adhesion, and pathogenesis. We hypothesized that identification of repeat-containing putative cell wall proteins in the human pathogen Aspergillus fumigatus may reveal novel pathogenesis-related elements. Here, we report that the genome of A. fumigatus contains as many as 292 genes with internal repeats. Fourteen of 30 selected genes showed size variation of their repeat-containing regions among 11 clinical A. fumigatus isolates. Four of these genes, Afu3g08990, Afu2g05150 (MP-2), Afu4g09600, and Afu6g14090, encode putative cell wall proteins containing a leader sequence and a glycosylphosphatidylinositol anchor motif. All four genes are expressed and produce variable-size mRNA encoding a discrete number of repeat amino acid units. Their expression was altered during development and in response to cell wall-disrupting agents. Deletion of one of these genes, Afu3g08990, resulted in a phenotype characterized by rapid conidial germination and reduced adherence to extracellular matrix suggestive of an alteration in cell wall characteristics. The Afu3g08990 protein was localized to the cell walls of dormant and germinating conidia. Our findings suggest that a subset of the A. fumigatus cell surface proteins may be hypervariable due to recombination events in their internal tandem repeats. This variation may provide the functional diversity in cell surface antigens which allows rapid adaptation to the environment and/or elusion of the host immune system.

Levdansky, Emma; Romano, Jacob; Shadkchan, Yona; Sharon, Haim; Verstrepen, Kevin J.; Fink, Gerald R.; Osherov, Nir

2007-01-01

331

Coding tandem repeats generate diversity in Aspergillus fumigatus genes.  

PubMed

Genes containing multiple coding mini- and microsatellite repeats are highly dynamic components of genomes. Frequent recombination events within these tandem repeats lead to changes in repeat numbers, which in turn alters the amino acid sequence of the corresponding protein. In bacteria and yeasts, the expansion of such coding repeats in cell wall proteins is associated with alterations in immunogenicity, adhesion, and pathogenesis. We hypothesized that identification of repeat-containing putative cell wall proteins in the human pathogen Aspergillus fumigatus may reveal novel pathogenesis-related elements. Here, we report that the genome of A. fumigatus contains as many as 292 genes with internal repeats. Fourteen of 30 selected genes showed size variation of their repeat-containing regions among 11 clinical A. fumigatus isolates. Four of these genes, Afu3g08990, Afu2g05150 (MP-2), Afu4g09600, and Afu6g14090, encode putative cell wall proteins containing a leader sequence and a glycosylphosphatidylinositol anchor motif. All four genes are expressed and produce variable-size mRNA encoding a discrete number of repeat amino acid units. Their expression was altered during development and in response to cell wall-disrupting agents. Deletion of one of these genes, Afu3g08990, resulted in a phenotype characterized by rapid conidial germination and reduced adherence to extracellular matrix suggestive of an alteration in cell wall characteristics. The Afu3g08990 protein was localized to the cell walls of dormant and germinating conidia. Our findings suggest that a subset of the A. fumigatus cell surface proteins may be hypervariable due to recombination events in their internal tandem repeats. This variation may provide the functional diversity in cell surface antigens which allows rapid adaptation to the environment and/or elusion of the host immune system. PMID:17557878

Levdansky, Emma; Romano, Jacob; Shadkchan, Yona; Sharon, Haim; Verstrepen, Kevin J; Fink, Gerald R; Osherov, Nir

2007-06-08

332

The Evolution of Tandemly Repetitive DNA: Recombination Rules  

PubMed Central

Variable numbers of tandem repeats (VNTRs), which include hypervariable regions, minisatellites and microsatellites, can be assigned together with satellite DNAs to define a class of noncoding tandemly repetitive DNA (TR-DNA). The evolution of TR-DNA is assumed to be driven by an unbiased recombinational process. A simulation model of unequal exchange is presented and used to investigate the evolutionary persistence of single TR-DNA lineages. Three different recombination rules are specified to govern the expansion and contraction of a TR-DNA lineage from an initial array of two repeats to, finally, a single repeat allele, which cannot participate in a misalignment and exchange process. In the absence of amplification or selection acting to bias array evolution toward expansion, the probability of attaining a target array size is a function only of the initial number of repeats. We show that the proportions of lineages attaining a targeted array size are the same irrespective of recombination rule and rate, demonstrating that our simulation model is well behaved. The time taken to attain a target array size, the persistence of the target array, and the total persistence time of repetitive array structure, are functions of the initial number of repeats, the rate of recombination, and the rules of misalignment preceding recombinational exchange. These relationships are investigated using our simulation model. While misalignment contraint is probably greatest for satellite DNA it also seems important in accounting for the evolution of VNTR loci including minisatellites. This conclusion is consistent with the observed nonrandom distributions of VNTRs and other TR-DNAs in the human genome.

Harding, R. M.; Boyce, A. J.; Clegg, J. B.

1992-01-01

333

Pulsating Tandem Microbubble for Localized and Directional Single Cell Membrane Poration  

PubMed Central

The interaction of laser-generated tandem microbubble (maximum diameter about 50 ?m) with single (rat mammary carcinoma) cells is investigated in a 25-?m liquid layer. Anti-phase and coupled oscillation of the tandem microbubble leads to the formation of alternating, directional microjets (with max. microstreaming velocity of 10 m/s) and vortices (max. vorticity of 350,000 s?1) in opposite directions. Localized and directional membrane poration (200 nm to 2 ?m in pore size) can be produced by the tandem microbubble in an orientation and proximity dependent manner, which is absence from a single oscillating microbubble of comparable size and at the same stand-off distance.

Sankin, G.N.; Yuan, F.; Zhong, P.

2013-01-01

334

Pulsating Tandem Microbubble for Localized and Directional Single-Cell Membrane Poration  

NASA Astrophysics Data System (ADS)

The interaction of laser-generated tandem microbubble (maximum diameter of about 50?m) with single (rat mammary carcinoma) cells is investigated in a 25-?m liquid layer. Antiphase and coupled oscillation of the tandem microbubble leads to the formation of alternating, directional microjets (with max microstreaming velocity of 10m/s) and vortices (max vorticity of 350000s-1) in opposite directions. Localized and directional membrane poration (200 nm to 2?m in pore size) can be produced by the tandem microbubble in an orientation and proximity-dependent manner, which is absent from a single oscillating microbubble of comparable size and at the same stand-off distance.

Sankin, G. N.; Yuan, F.; Zhong, P.

2010-08-01

335

Modulation of RNA Metal Binding by Flanking Bases: 15N NMR Evaluation of GC, Tandem GU, and Tandem GA Sites  

PubMed Central

15N NMR chemical shift changes in the presence of Mg(H2O)62+, Zn2+, Cd2+, and Co(NH3)63+ were used to probe the effect of flanking bases on metal binding sites in three different RNA motifs. We found that: for GC pairs, the presence of a flanking purine creates a site for the soft metals Zn2+ and Cd2+ only; a GG·UU motif selectively binds only Co(NH3)63+, while a UG·GU motif binds none of these metals; a 3? guanosine flanking the adenosine of a sheared GA·AG pair creates an unusually strong binding site that precludes binding to the cross-strand stacked guanosines within the tandem pair.

Wang, Weimin; Zhao, Jianwei; Han, Qianwei; Wang, Gang; Yang, Gengcheng; Shallop, Anthony J.; Liu, Jane; Gaffney, Barbara L.; Jones, Roger A.

2009-01-01

336

Axisymmetric Tandem Mirror Magnetic Fusion Energy Power Plant with Thick Liquid-Walls.  

National Technical Information Service (NTIS)

A fusion power plant is described that utilizes a new version of the tandem mirror device including spinning liquid walls. The magnetic configuration is evaluated with an axisymmetric equilibrium code predicting an average beta of 60%. The geometry allows...

R. W. Moir T. D. Rognlien

2006-01-01

337

Tandem Repeat Regions within the Burkholderia pseudomallei Genome and their Application for High-Resolution Genotyping.  

National Technical Information Service (NTIS)

Background:The facultative, intracellular bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a serious infectious disease of humans and animals. We identified and categorized large tandem repeat arrays and their distribution throug...

C. L. Friedman H. Hornstra J. M. Schupp J. M. U'Ren T. Pearson

2007-01-01

338

Thermal-Hydraulics Design Comparisons for the Tandem Mirror Hybrid Reactor Blanket.  

National Technical Information Service (NTIS)

The Tandem Mirror Hybrid Reactor (TMHR) is a cylindrical reactor, and the fertile materials and tritium breeding fuel elements can be arranged with radial or axial orientation in the blanket module. Thermal-hydraulics performance comparisons were made bet...

C. P. C. Wong Y. S. Yang K. R. Schultz

1980-01-01

339

Nondestructive Evaluation of Double Bevel T-Joint by Tandem Array Ultrasonic Transducer  

NASA Astrophysics Data System (ADS)

The double bevel T-joint is one of the most fundamental joints of steel bridges. Double bevel T-joint can be seen at beam-column connection of bridge pier. In the Japanese specifications, the welding should be full penetration. However, weld defect of incomplete penetration could be left in the joint due to the lack of quality control in welding. Fatigue cracks can be propagated from the weld defects. The authors developed a tandem array transducer. The tandem array transducer consists of 10 elements aligned in the same direction. Tandem scanning can be simulated by the transducer. Image reconstruction of incomplete penetration by synthetic aperture focusing technique was carried out. The test results showed sufficient detectability of incomplete penetration by the tandem array transducer. Height of incomplete of penetration could be estimated.

Shirahata, H.; Miki, C.; Yamaguchi, R.

2003-03-01

340

Annual report of the Tandem Accelerator Center, University of Tsukuba. April 1, 1995 - March 31, 1996.  

National Technical Information Service (NTIS)

This annual report includes the research activities from April, 1995 to March, 1996. The 12 UD Pelletron tandem accelerator has been operated successfully to provide sufficient beam time for experiments. The stable operation of the accelerator brought out...

1996-01-01

341

Tandem Polymer Solar Cells Featuring a Spectrally Matched Low-Bandgap Polymer  

SciTech Connect

Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for polymer solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of a suitable low-bandgap polymer. Here, we demonstrate highly efficient single and tandem polymer solar cells featuring a low-bandgap conjugated polymer (PBDTT-DPP: bandgap, {approx}1.44 eV). A single-layer device based on the polymer provides a power conversion efficiency of {approx}6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which is, to the best of our knowledge, the highest certified efficiency for a polymer solar cell to date.

Dou, L.; You, J.; Yang, J.; Chen, C. C.; He, Y.; Murase, S.; Moriarty, T.; Emery, K.; Li, G.; Yang, Y.

2012-03-01

342

Elimination of modulation effects in a tandem Fabry-Perot interferometer  

Microsoft Academic Search

Intere´talon feedback in a tandem Fabry–Perot spectrometer will often be manifested by a frequency-modulated spectrum. This undesirable modulation can be removed in a simple and consistent manner without significant loss of signal.

J. J. Vanderwal; D. Walton; Z. Hu

1987-01-01

343

Synfuels from fusion: producing hydrogen with the Tandem Mirror Reactor and thermochemical cycles  

SciTech Connect

This volume contains the following sections: (1) the Tandem Mirror fusion driver, (2) the Cauldron blanket module, (3) the flowing microsphere, (4) coupling the reactor to the process, (5) the thermochemical cycles, and (6) chemical reactors and process units. (MOW)

Werner, R.W.; Ribe, F.L.

1981-01-21

344

Biocatalyst Enhancement  

EPA Science Inventory

The increasing availability of enzyme collections has assisted attempts by pharmaceutical producers to adopt green chemistry approaches to manufacturing. A joint effort between an enzyme producer and a pharmaceutical manufacturer has been enhanced over the past three years by ena...

345

Identification of Protein Interacting Partners Using Tandem Affinity Purification  

PubMed Central

A critical and often limiting step in understanding the function of host and viral proteins is the identification of interacting cellular or viral protein partners. There are many approaches that allow the identification of interacting partners, including the yeast two hybrid system, as well as pull down assays using recombinant proteins and immunoprecipitation of endogenous proteins followed by mass spectrometry identification1. Recent studies have highlighted the utility of double-affinity tag mediated purification, coupled with two specific elution steps in the identification of interacting proteins. This approach, termed Tandem Affinity Purification (TAP), was initially used in yeast2,3 but more recently has been adapted to use in mammalian cells4-8. As proof-of-concept we have established a tandem affinity purification (TAP) method using the well-characterized eukaryotic translation initiation factor eIF4E9,10.The cellular translation factor eIF4E is a critical component of the cellular eIF4F complex involved in cap-dependent translation initiation10. The TAP tag used in the current study is composed of two Protein G units and a streptavidin binding peptide separated by a Tobacco Etch Virus (TEV) protease cleavage sequence. The TAP tag used in the current study is composed of two Protein G units and a streptavidin binding peptide separated by a Tobacco Etch Virus (TEV) protease cleavage sequence8. To forgo the need for the generation of clonal cell lines, we developed a rapid system that relies on the expression of the TAP-tagged bait protein from an episomally maintained plasmid based on pMEP4 (Invitrogen). Expression of tagged murine eIF4E from this plasmid was controlled using the cadmium chloride inducible metallothionein promoter. Lysis of the expressing cells and subsequent affinity purification via binding to rabbit IgG agarose, TEV protease cleavage, binding to streptavidin linked agarose and subsequent biotin elution identified numerous proteins apparently specific to the eIF4E pull-down (when compared to control cell lines expressing the TAP tag alone). The identities of the proteins were obtained by excision of the bands from 1D SDS-PAGE and subsequent tandem mass spectrometry. The identified components included the known eIF4E binding proteins eIF4G and 4EBP-1. In addition, other components of the eIF4F complex, of which eIF4E is a component were identified, namely eIF4A and Poly-A binding protein. The ability to identify not only known direct binding partners as well as secondary interacting proteins, further highlights the utility of this approach in the characterization of proteins of unknown function.

Thorne, Lucy; Goodfellow, Ian

2012-01-01

346

Penetration enhancers  

Microsoft Academic Search

One long-standing approach for improving transdermal drug delivery uses penetration enhancers (also called sorption promoters or accelerants) which penetrate into skin to reversibly decrease the barrier resistance. Numerous compounds have been evaluated for penetration enhancing activity, including sulphoxides (such as dimethylsulphoxide, DMSO), Azones (e.g. laurocapram), pyrrolidones (for example 2-pyrrolidone, 2P), alcohols and alkanols (ethanol, or decanol), glycols (for example propylene

Adrian C Williams; Brian W Barry

2004-01-01

347

Distribution and evolution of a tandemly repeated DNA sequence in the family brassicaceae  

Microsoft Academic Search

Summary  A tandemly repeated DNA sequence present in several species of the family Brassicaceae has been characterized. Digestion of\\u000a the genomic DNA from 17 species from this family revealed the presence of tandem repeats of about 175 bp monomeric size in\\u000a 6 of the 11 investigated genera. All investigated genera within the tribe Brassiceae contained the sequence. TheBrassica napus Hind III

C. Halldén; T. Bryngelsson; T. Sfitt; M. Gustafsson

1987-01-01

348

Physics of Open-Field Line Plasmas 4. Formation of Electrostatic Potential in a Tandem Mirror  

NASA Astrophysics Data System (ADS)

The formation of electrostatic potential in a tandem mirror is reviewed. The plug potential and thermal barrier potential formations are first presented. The continuous potential profile across the mirror throat and the plug is discussed, which is required to avoid the formation of a sheath potential. The neoclassical radial transport is shown finally in order to calculate the potential radial profile in the central cell of a tandem mirror with finite endplate resistance.

Katanuma, Isao

349

Eu(fod) 3-catalyzed tandem regiospecific rearrangement of divinyl alkoxyacetates and Diels–Alder reaction  

Microsoft Academic Search

Unsymmetrical divinyl alkoxyacetates (such as 7a) undergo a Eu(fod)3-catalyzed regiospecific allylic rearrangement to form C5-substituted (E)-2-ethoxy-1,3-dienes at room temperature. When the rearrangement of 7a was carried out in the presence of maleic anhydride, a tandem allylic rearrangement and Diels–Alder reaction occurred to give the adduct 11. Reactions of other dienophiles in this tandem procedure were examined.

Wei-Min Dai; Wing Leung Mak; Anxin Wu

2000-01-01

350

Integrated tandem traveling-wave electroabsorption modulators for >100 Gbit\\/s OTDM applications  

Microsoft Academic Search

Integrated tandem traveling-wave electroabsorption modulators are demonstrated as high-speed optical short pulse generators and demultiplexers for >100 Gbit\\/s optical time-division-multiplexed systems. The tandem significantly increases the extinction ratio and further compresses the optical pulses in comparison to a single modulator. An extinction ratio of ?50 dB is achieved while optical pulses of 4-6 ps width at 30-40 GHz are generated.

Volkan Kaman; Yi-Jen Chiu; Thomas Liljeberg; Sheng Z. Zhang; John E. Bowers

2000-01-01

351

Numerical analysis of the s1020 airfoils in tandem under different flapping configurations  

Microsoft Academic Search

The objective of this project is to improve the performance of the efficiency, thrust and lift of flapping wings in tandem\\u000a arrangement. This research investigates the effect of the arrangement of the airfoils in tandem on the performance of the\\u000a airfoils by varying the phase difference and distance between the airfoils. Three flapping configurations from an earlier\\u000a phase of a

K. B. Lim; W. B. Tay

2010-01-01

352

Proteomic LC–MS systems using nanoscale liquid chromatography with tandem mass spectrometry  

Microsoft Academic Search

Current nano-scale liquid chromatography–tandem mass spectrometry (nanoLC–MS\\/MS) approaches in proteome research are reviewed from an analytical perspective. For comprehensive analysis of cellular proteins, analytical methods with higher resolution, sensitivity, and wider dynamic range are required. Miniaturized LC coupled with tandem mass spectrometry is currently one of the most versatile techniques. In this review, the current status of nanoLC–MS\\/MS systems as

Yasushi Ishihama

2005-01-01

353

The coming of age of liquid chromatography coupled to tandem mass spectrometry in the endocrinology laboratory  

Microsoft Academic Search

Liquid chromatography coupled to tandem mass spectrometry (LC–MS\\/MS) has been rapidly incorporated in the routine of the endocrinology laboratory. Most endocrinologists are aware of the benefits afforded by this technique and tandem mass spectrometers are clearly no longer a mere research method but an important tool widely used for diagnosis. In the last 15 years, LC–MS\\/MS has replaced techniques such

Valdemir Melechco Carvalho

354

R&D issues in scale-up and manufacturing of amorphous silicon tandem modules  

SciTech Connect

R & D on amorphous silicon based tandem junction devices has improved the throughtput, the material utilization, and the performance of devices on commercial tin oxide coated glass. The tandem junction technology has been scaled-up to produce 8.6&hthinsp;Ft{sup 2} monolithically integrated modules in manufacturing at the TF1 plant. Optimization of performance and stability of these modules is ongoing. {copyright} {ital 1999 American Institute of Physics.}

Arya, R.R.; Carlson, D.E.; Chen, L.F.; Ganguly, G.; He, M.; Lin, G.; Middya, R.; Wood, G.; Newton, J.; Bennett, M.; Jackson, F.; Willing, F. [Solarex, a Business Unit of Amoco/Enron Solar, 826 Newtown-Yardley Road, Newtown, Pennsylvania 18940 (United States)

1999-03-01

355

Detection and quantification of the sulfated disaccharides in chondroitin sulfate by electrospray tandem mass spectrometry  

Microsoft Academic Search

A new method of identifying and quantifying the disaccharide building blocks of glycosaminoglycans is introduced. The polysaccharides\\u000a are subjected to an enzymatic digestion that releases the sulfated disaccharides. The disaccharides are then identified using\\u000a a combination of electrospray ionization mass spectrometry and tandem mass spectrometry. Quantification of the isomeric disaccharides\\u000a is also achieved by tandem mass spectrometry, using a recently

Heather Desaire; Julie A. Leary

2000-01-01

356

A software tool for the selection of Tandem Repeats for MLVA analysis.  

PubMed

DNA fingerprinting is a reliable tool for identifying, tracing and characterizing bacterial clonal population structure. A recent technique is given by the Multiple Loci VNTR Analysis (MLVA), where VNTR denotes Variable Number of Tandem Repeats, that meets the need for fast and reliable typing methods by combining the polymorphic nature of tandem repeats (TR) and the use of Polymerase Chain Reaction (PCR) methodology. PMID:24110475

D'Avenio, Giuseppe; Grigioni, Mauro; Creti, Roberta

2013-07-01

357

Rapid quantitative analysis of oxiracetam in human plasma by liquid chromatography\\/electrospray tandem mass spectrometry  

Microsoft Academic Search

A rapid and accurate reversed-phase liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) method has been developed and validated for the quantitative determination of oxiracetam in human plasma. Oxiracetam, a highly polar compound, was successfully retained by Atlantis™ dC18 reversed-phase column and detected with triple-quadrupole tandem mass spectrometry. After addition of internal standard (piracetam) to human plasma, plasma was simply precipitated with two

Junghyun Son; Jaeick Lee; Mijin Lee; Eunyoung Lee; Jung Hwa Lee; Sookie La; Dong-Hyun Kim

2004-01-01

358

STRBase: a short tandem repeat DNA database for the human identity testing community  

Microsoft Academic Search

The National Institute of Standards and Technology (NIST) has compiled and maintained a Short Tandem Repeat DNA Internet Database (http:\\/\\/www.cstl.nist.gov\\/ biotech\\/strbase\\/) since 1997 commonly referred to as STRBase. This database is an information resource for the forensic DNA typing community with details on commonly used short tandem repeat (STR) DNA markers. STRBase consolidates and organizes the abundant literature on this

Christian M. Ruitberg; Dennis J. Reeder; John M. Butler

2001-01-01

359

Vacuum measurements on the Tandem Mirror Experiment Upgrade (TMX-U) fusion experiment  

SciTech Connect

The gas inventory of the Tandem Mirror Experiment Upgrade (TMX-U) must be carefully controlled, if it is to successfully create various plasma configurations for thermal-barrier experiments designed to provide an improved performance for tandem-mirror experiments. This paper is a progress report on the calibration methods and pressure measurements of machine conditions deriving from recently improved neutral-beam gas control, and changes to the internal baffling geometry and the gettering system.

Calderon, M.O.; Hunt, A.L.; Lang, D.D.; Nexsen, W.E.; Pickles, W.L.; Turner, W.C.

1983-08-12

360

The spectral p-n junction model for tandem solar-cell design  

Microsoft Academic Search

Tandem solar cells can have significantly higher efficiencies than single-junction solar cells because they convert a larger fraction of the incident solar spectrum to electricity. For the design of tandem solar cells the spectral p-n junction model is proposed. It is based on tabulated standard spectra, on the fit of experimentally achieved open-circuit voltages, and assumes a quantum efficiency of

M. E. Nell; A. M. Barnett

1987-01-01

361

The DCX-domain tandems of doublecortin and doublecortin-like kinase  

Microsoft Academic Search

The doublecortin-like domains (DCX), which typically occur in tandem, are novel microtubule-binding modules. DCX tandems are found in doublecortin, a 360-residue protein expressed in migrating neurons; the doublecortin-like kinase (DCLK); the product of the RP1 gene that is responsible for a form of inherited blindness; and several other proteins. Mutations in the gene encoding doublecortin cause lissencephaly in males and

Myung Hee Kim; Tomasz Cierpicki; Urszula Derewenda; Daniel Krowarsch; Yuanyi Feng; Yancho Devedjiev; Zbigniew Dauter; Christopher A. Walsh; Jacek Otlewski; John H. Bushweller; Zygmunt S. Derewenda

2003-01-01

362

Characterization of inositol phosphorylceramides from Leishmania major by tandem mass spectrometry with electrospray ionization  

Microsoft Academic Search

We describe tandem mass spectrometric approaches, including multiple stage ion-trap and source collisionally activated dissociation\\u000a (CAD) tandem mass spectrometry with electrospray ionization (ESI) to characterize inositol phosphorylceramide (IPC) species\\u000a seen as [M ? H]? and [M ? 2H + Li]? ions in the negative-ion mode as well as [M + H]+, [M + Li]+, and [M ? H + 2Li]+

Fong-Fu Hsu; John Turk; Kai Zhang; Stephen M. Beverley

2007-01-01

363

The tandem inverter: combining the advantages of voltage-source and current-source inverters  

Microsoft Academic Search

A combination of a current-source primary inverter and a voltage-source secondary inverter is proposed as the so-called tandem inverter. The primary inverter operates in the square-wave mode, handling most of the converted power, while its output harmonic currents are compensated by the much smaller secondary inverter. As a result, the tandem inverter, to be used for AC motor control, combines

A. M. Trznadlowski; F. Blaabjerg; J. K. Pedersen; N. Patriciu

1998-01-01

364

Structural determination by atmospheric pressure photoionization tandem mass spectrometry of some compounds isolated from the SARA fractions obtained from bitumen.  

PubMed

We have identified compounds obtained from the SARA fractions of bitumen by using atmospheric pressure photoionization mass spectrometry and low-energy collision tandem mass spectrometric analyses with a QqToF-MS/MS hybrid instrument. The identified compounds were isolated from the maltene saturated oil and the aromatic fractions of the SARA components of a bitumen. The QqToF instrument had sufficient mass resolution to provide accurate molecular weight information and to enhance the tandem mass spectrometry results. The APPI-QqToF-MS analysis of the separated compounds showed a series of protonated molecules [M + H](+) and molecular ions [M](+?) of the same mass but having different chemical structures, in the maltene saturated oil and the aromatic SARA fractions. These isobaric ions were a molecular ion [M2 ](+?) at m/z 418.2787 and a protonated molecule [M5 + H](+) at m/z 287.1625 in the saturated oil fraction, and molecular ions [M6 ](+?) at m/z 418.1584 and [M7 ](+?) at m/z 287.1285 in the aromatic fraction. The identification of this series of chemical compounds was achieved by performing CID-MS/MS analyses of the molecular ions [M](+?) ([M1 ](+?) at m/z 446. 2980, [M2 ](+?) at m/z 418.2787, [M3 ](+?) at m/z 360.3350 and [M4 ](+?) at m/z 346.2095) in the saturated oil fraction and of the [M5 + H](+) ion at m/z 287.1625 also in the saturated oil fraction. The observed CID-MS/MS fragmentation differences were explained by proposed different breakdown processes of the precursor ions. The presented tandem mass spectrometric study shows the capability of MS/MS experiments to differentiate between different classes of chemical compounds of the SARA components of bitumen and to explain the reasons for the observed mass spectrometric differences. However, greater mass resolution than that provided by the QqToF-MS/MS instrument would be required for the analysis of the asphaltene fraction of bitumen. PMID:23657961

Tachon, Nadine; Jahouh, Farid; Delmas, Michel; Banoub, Joseph H

2011-09-30

365

Assessing the Role of Tandem Repeats in Shaping the Genomic Architecture of Great Apes  

PubMed Central

Background Ancestral reconstructions of mammalian genomes have revealed that evolutionary breakpoint regions are clustered in regions that are more prone to break and reorganize. What is still unclear to evolutionary biologists is whether these regions are physically unstable due solely to sequence composition and/or genome organization, or do they represent genomic areas where the selection against breakpoints is minimal. Methodology and Principal Findings Here we present a comprehensive study of the distribution of tandem repeats in great apes. We analyzed the distribution of tandem repeats in relation to the localization of evolutionary breakpoint regions in the human, chimpanzee, orangutan and macaque genomes. We observed an accumulation of tandem repeats in the genomic regions implicated in chromosomal reorganizations. In the case of the human genome our analyses revealed that evolutionary breakpoint regions contained more base pairs implicated in tandem repeats compared to synteny blocks, being the AAAT motif the most frequently involved in evolutionary regions. We found that those AAAT repeats located in evolutionary regions were preferentially associated with Alu elements. Significance Our observations provide evidence for the role of tandem repeats in shaping mammalian genome architecture. We hypothesize that an accumulation of specific tandem repeats in evolutionary regions can promote genome instability by altering the state of the chromatin conformation or by promoting the insertion of transposable elements.

Farre, Marta; Bosch, Montserrat; Lopez-Giraldez, Francesc; Ponsa, Montserrat; Ruiz-Herrera, Aurora

2011-01-01

366

Numerical analysis of the s1020 airfoils in tandem under different flapping configurations  

NASA Astrophysics Data System (ADS)

The objective of this project is to improve the performance of the efficiency, thrust and lift of flapping wings in tandem arrangement. This research investigates the effect of the arrangement of the airfoils in tandem on the performance of the airfoils by varying the phase difference and distance between the airfoils. Three flapping configurations from an earlier phase of a research which gives high efficiency, thrust and lift are used in the tandem simulation. It is found all the different flapping configurations show improvement in the efficiency, thrust or lift when the distance between the two airfoils and the phase angle between the heaving positions of the two airfoils are optimal. The average thrust coefficient of the tandem arrangement managed to attain more than twice that of the single one (4.84 vs. 2.05). On the other hand, the average lift coefficient of the tandem arrangement also increased to 4.59, as compared to the original single airfoil value of 3.04. All these results obtained will aid in the design of a better ornithopter with tandem wing arrangement.

Lim, K. B.; Tay, W. B.

2010-05-01

367

OPV Tandems with CNTS: Why Are Parallel Connections Better Than Series Connections  

NASA Astrophysics Data System (ADS)

The efficiency of organic photovoltaic cells can be increased in tandem OPV structures with complementary light absorption in top and bottom sub-cells. We demonstrate that strong transparent CNT sheets can be used as an effective charge collector interlayer in OPV and hybrid tandem solar cells. Most importantly we show that CNT sheets can be used in monolithic parallel tandems (P-T) as common a electrode interconnect between top and bottom sub-cells. For achieving good performance one of these subcells in P-T should be of inverted type. We achieved good inversion in OPV, using ZnO nanoparticles, which act as hole barrier layers and invert a typical anode ITO into a cathode. With this inverted bottom cell the efficiency of P-T is significantly improved, as compared to our earlier results. We briefly discuss the modeling analysis of OPV tandems and derive an optimal set of parameters, for highest efficiency P-T. Our simple model shows that for tandems with unbalanced photocurrents but similar open circuit voltages the optimized P-T architecture is always better than conventional series tandem (S-T) geometry. Indeed the experimental comparison of P-T with S-T for hybrids of OPV and dye sensitized solar cells demonstrate the imporved efficiency of the former.

Mielczarek, Kamil; Cook, Alexander; Kuznetsov, Alexander; Zakhidov, Anvar

368

Inhibition of the PI3K/AKT-NF-?B pathway with curcumin enhanced radiation-induced apoptosis in human Burkitt's lymphoma.  

PubMed

The phosphatidylinositol-3-kinase (PI3K) / protein kinase B (AKT) signal transduction pathway is commonly misregulated in lymphoma and associated with tumorigenesis and enhanced resistance to radiotherapy. Curcumin has been shown to inhibit the PI3K/AKT signal transduction pathway in several tumor models. In this study, we found that curcumin inhibits constitutive and radiation-induced expression of the PI3K/AKT pathway and its downstream regulator nuclear factor kappaB (NF-?B) in human Burkitt's lymphoma, a high-grade non-Hodgkin's lymphoma (NHL). We further demonstrated that the blockage of radiation-induced activation of the PI3K/AKT pathway and its downstream regulator NF-?B by either curcumin or specific PI3/AKT inhibitors (LY294002 for PI3K or SH-5 for AKT) enhance apoptosis in three human Burkitt's lymphoma cell lines (Namalwa, Ramos, and Raji) that were treated with ionizing radiation. However, no synergic effect on radiation-induced apoptosis was found in the cells co-pretreated with curcumin combined with LY294002 or curcumin combined with SH-5. The results from this study suggest that curcumin might play an important role in radiotherapy of high-grade NHL through inhibition of the PI3K/AKT-dependent NF-?B pathway. PMID:23603894

Qiao, Qiao; Jiang, Yuanjun; Li, Guang

2013-01-01

369

Quantitative analysis of acetaminophen and its primary metabolites in small plasma volumes by liquid chromatography-tandem mass spectrometry.  

PubMed

A fast and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the simultaneous determination of acetaminophen (APAP) and its glucuronide and sulfate metabolites (APAP-GLU and APAP-SUL) in small plasma volumes. This method included a simple step of sample preparation and a chromatographic separation on an LC-MS-MS system equipped with an electrospray ionization source and a tandem triple quadrupole mass spectrometer in multiple reaction monitoring mode. The analytes and internal standard, APAP deuterated analog, were separated on a C18 column (3.0 µm, 2.1 × 100 mm), using aqueous 1% formic acid and methanol (80:20, v/v) as the mobile phase. The LC-MS-MS method was validated for accuracy, precision, linearity, extraction efficiency, process efficiency and matrix effect. Calibration curves were obtained by fortifying drug-free plasma and ranges of linearity were set between 0.25-20 mg/L. The mean correlation coefficients, r², were >0.99 for APAP and its metabolites. The inter-day and intra-day precision values were less than 11.75 and 13.03%, respectively, at the lower limit of quantification concentration. The usability of the method was demonstrated by studying APAP metabolism in C57BL/6J wild-type and obese ob/ob female mice, in which only small plasma volumes were available. The results showed that APAP glucuronidation was enhanced in obese mice, suggesting that changes in APAP metabolism could modify its toxicity in obesity and related fatty liver disease. PMID:23316031

Gicquel, Thomas; Aubert, Jacinthe; Lepage, Sylvie; Fromenty, Bernard; Morel, Isabelle

2013-01-12

370

High-performance liquid chromatographic/mass spectrometric and high-performance liquid chromatographic/tandem mass spectrometric analysis of carbamate pesticides.  

PubMed

The thermospray ionization mass spectra of selected carbamate pesticides were obtained using both single-stage and triple-stage quadrupole mass spectrometry in conjunction with high-performance liquid chromatography. With the use of the single-quadrupole mass spectrometer and ammonium acetate as the mobile phase, enhanced sensitivity for the analytes of interest was obtained by monitoring the relatively intact [M + 1]+ or [M + 18]+ adduct ions. Further structural characterization of the carbamates was not readily obtainable owing to the lack of diagnostic bond cleavages. The single-stage quadrupole analyses were therefore complemented by triple-stage quadrupole analyses. Here, collisionally activated daughter ion spectra exhibited structure-specific fragmentations. In addition, the enhanced selectivity and specificity provided by tandem mass spectrometry allowed use of the technique as a rapid screening tool for carbamates without the need for the chromatographic separation step. PMID:2713548

Chiu, K S; Van Langenhove, A; Tanaka, C

1989-03-01

371

Process aspects of hydrogen production using the Tandem Mirror Reactor  

SciTech Connect

An SO/sub 3/ decomposer design is presented which provides the necessary production of SO/sub 2/ + O/sub 2/ for the thermochemical production of H/sub 2/ using the thermal heat from the blanket of a Tandem Mirror Fusion Reactor. The decomposer is a catalytic, fluidized bed reactor operating at 1050/sup 0/K that contains internal heat exchanger tubes to provide the heat for the highly endothermic SO/sub 3/ decomposition reactor. The conversion per pass is around 55% using either CuO or platinum-based catalysts. We examine the impact on the design of varying the temperature 100/sup 0/C higher or lower than 1050/sup 0/K and we also look at both liquid sodium and helium as the heat transfer medium to carry the heat from the TMR to the decomposer. To drive a H/sub 2/ plant with 15 x 10/sup 6/ sm/sup 3//d there would be around 7 decomposers, 10 m in height and 6 m in diameter, made of Incoloy-800H at $24/kg at a total capital cost of around $50 million - which translates to about 12 cents/GJ of H/sub 2/ produced with conventional economics. Helium-driven units would approximately double the cost in trade for the additional safety isolation.

Galloway, T.R.

1980-10-08

372

A variable dispersion array detector for a tandem mass spectrometer  

NASA Astrophysics Data System (ADS)

Incorporation of a pair of quadrupole lenses and one octapole lens after the second magnetic field of a JEOL HX110/HX110 tandem mass spectrometer permits varying the dispersion and therefore the mass range that can be focused on a 2 in array detector. This range can be adjusted from a value of 1: 1.04 to 1: 1.3 for the ratio of low m/z to high m/z falling at the extremes of the detector. The ratio is governed by the d.c. potentials on the lenses which also changes the angle of the resulting focal plane and thus requires that the position of the array detector must be changed accordingly. In the system described, all these variables are under computer control and can be adjusted within 1 s, thus allowing for a change even during the recording of a spectrum if one wishes to minimize the number of segments to be recorded to cover the entire spectrum while still maintaining unit mass resolution. The variable range array detector is useful for the recording of normal mass spectra as well as those generated upon collision induced decomposition (CID) of precursor ions. In the latter case, the refocusing of the ion beams through the quadrupole lens system is more complex but the software controls the lens potentials accordingly. The system has been used to record the normal or CID spectra of peptides, either from a static sample or eluting from a high performance liquid chromatograph.

Hill, James A.; Biller, James E.; Biemann, Klaus

1991-12-01

373

Electrospray tandem mass spectrometric analysis of novel synthetic quinoxalinone derivatives.  

PubMed

Electrospray ionization tandem mass spectrometry (ESI-MS/MS) using a hybrid QqToF-MS/MS instrument has aided the structural characterization and differentiation of a novel series of medicinal synthetic 1-N-glycoside-quinoxalinone derivatives. These derivatives 7 and 8 are formed by an amino bond between the cyclic N-1 of the quinoxaline moiety and the C-6 position of a fully protected methyl or allyl alpha-D-mannofuranoside 3 and 4, and subsequent deprotection of the mannopyranoside moiety. In general the novel synthetic quinoxaline derivatives afforded the protonated molecules in ESI. The breakdown routes of the protonated molecules were rationalized by conducting low-energy CID-MS/MS analyses. In addition, re-confirmation of the various established fragmentation routes was achieved by conducting a series of ESI-CID-QqTof-MS/MS product ion scans on various selected precursor ions, which were initiated by CID in the atmospheric pressure/vacuum interface using a higher declustering potential. ESI-QqToF-MS/MS analysis has proven to be a specific and very sensitive method for the structural identification in the gas phase of these novel glycoquinoxalinamine derivatives. PMID:18286668

Joly, Nicolas; Jarmoumi, Chakir; Massoui, Mohamed; Essassi, El Mokhtar; Martin, Patrick; Banoub, Joseph H

2008-01-01

374

Vacuum vessel for the tandem Mirror Fusion Test Facility  

SciTech Connect

In 1980, the US Department of Energy gave the Lawrence Livermore National Laboratory approval to design and build a tandem Mirror Fusion Test Facility (MFTF-B) to support the goals of the National Mirror Program. We designed the MFTF-B vacuum vessel both to maintain the required ultrahigh vacuum environment and to structurally support the 42 superconducting magnets plus auxiliary internal and external equipment. During our design work, we made extensive use of both simple and complex computer models to arrive at a cost-effective final configuration. As part of this work, we conducted a unique dynamic analysis to study the interaction of the 32,000-tonne concrete-shielding vault with the 2850-tonne vacuum vessel system. To maintain a vacuum of 2 x 10/sup -8/ torr during the physics experiments inside the vessel, we designed a vacuum pumping system of enormous capacity. The vacuum vessel (4200-m/sup 3/ internal volume) has been fabricated and erected, and acceptance tests have been completed at the Livermore site. The rest of the machine has been assembled, and individual systems have been successfully checked. On October 1, 1985, we began a series of integrated engineering tests to verify the operation of all components as a complete system.

Gerich, J.W.

1986-03-10

375

Mechanical design of the Tandem Mirror Experiment Upgrade vacuum system  

SciTech Connect

The Tandem Mirror Experiment Upgrade (TMX Upgrade) vacuum system uses most of the vacuum system from the original TMX and substantially increases its capabilities. The vacuum system provides the main structure for the experimental apparatus, as well as providing and maintaining the vacuum environment. The vacuum vessel provides the structure supporting all magnets, as they are contained inside the vacuum vessel, all of the neutral-beam injectors, and the various diagnostics. The vessel provides the main vacuum enclosure and the various access ports required by the magnet system, injector system, internal vacuum system, and plasma diagnostics. The vacuum environment is created and maintained by two systems, the external vacuum system and the internal vacuum system. The external system consists of mechanical pumps, turbopumps, and cryopumps, and creates a vacuum inside the vessel down to a minimum pressure of 10/sup -6/ Torr. The internal vacuum system further reduces the pressure into the 10/sup -8/ Torr range and provides the fast pumping required to handle the excess gas from the neutral-beam injector system during a plasma shot. The internal vacuum system consists of titanium sublimators and liquid nitrogen (LN) liners that separate the vacuum vessel into various pumping regions.

Lang, D.D.; Calderon, M.O.; Thomas, S.R.; Garner, D.R.

1981-09-24

376

Tandem cathode for proton exchange membrane fuel cells.  

PubMed

The efficiency of proton exchange membrane fuel cells is limited mainly by the oxygen reduction reaction at the cathode. The large cathodic overpotential is caused by correlations between binding energies of reaction intermediates in the reduction of oxygen to water. This work introduces a novel tandem cathode design where the full oxygen reduction, involving four electron-transfer steps, is divided into formation (equilibrium potential 0.70 V) followed by reduction (equilibrium potential 1.76 V) of hydrogen peroxide. The two part reactions contain only two electron-transfer steps and one reaction intermediate each, and they occur on different catalyst surfaces. As a result they can be optimized independently and the fundamental problem associated with the four-electron catalysis is avoided. A combination of density functional theory calculations and published experimental data is used to identify potentially active and selective materials for both catalysts. Co-porphyrin is recommended for the first step, formation of hydrogen peroxide, and three different metal oxides - SrTiO3(100), CaTiO3(100) and WO3(100) - are suggested for the subsequent reduction step. PMID:23661187

Siahrostami, Samira; Björketun, Mårten E; Strasser, Peter; Greeley, Jeff; Rossmeisl, Jan

2013-05-10

377

Rapid comparison of diacetylmorphine on banknotes by tandem mass spectrometry.  

PubMed

A procedure is described for the determination of the distribution of the contamination of banknotes with controlled drugs using tandem mass spectrometry. The method is illustrated using diacetylmorphine, which is the major active component of heroin. A series of banknotes is introduced into the mass spectrometer and the intensities of two product ions (m/z 328 and 268) derived from the precursor protonated molecule (m/z 370) are recorded. A banknote is considered contaminated if it shows a significant peak for both product ions, and if the ratio of intensities of these two peaks falls within accepted limits. The distribution of diacetylmorphine on sterling banknotes taken from general circulation within the UK can be modelled by an arcsin (square root) transformation of the data or by a log transformation of the data with a higher proportion of contamination. The two models were found to be in close agreement, predicting an upper limit (at 99.9% confidence) of contamination on banknotes from general circulation between 9 and 10%. The percentage contamination in a case study was calculated and compared to the background distribution using the two models proposed. This comparison revealed that the contamination present in the case study was inconsistent with that present on banknotes in general circulation. PMID:15988724

Ebejer, Karl A; Brereton, Richard G; Carter, James F; Ollerton, Samantha L; Sleeman, Richard

2005-01-01

378

Multilocus Variable-Number Tandem Repeat Typing of Mycobacterium ulcerans  

PubMed Central

The apparent genetic homogeneity of Mycobacterium ulcerans contributes to the poorly understood epidemiology of M. ulcerans infection. Here, we report the identification of variable number tandem repeat (VNTR) sequences as novel polymorphic elements in the genome of this species. A total of 19 potential VNTR loci identified in the closely related M. marinum genome sequence were screened in a collection of 23 M. ulcerans isolates, one Mycobacterium species referred to here as an intermediate species, and five M. marinum strains. Nine of the 19 loci were polymorphic in the three species (including the intermediate species) and revealed eight M. ulcerans and five M. marinum genotypes. The results from the VNTR analysis corroborated the genetic relationships of M. ulcerans isolates from various geographical origins, as defined by independent molecular markers. Although these results further highlight the extremely high clonal homogeneity within certain geographic regions, we report for the first time the discrimination of the two South American strains from Surinam and French Guyana. These findings support the potential of a VNTR-based genotyping method for strain discrimination within M. ulcerans and M. marinum.

Ablordey, Anthony; Swings, Jean; Hubans, Christine; Chemlal, Karim; Locht, Camille; Portaels, Francoise; Supply, Philip

2005-01-01

379

Detection of stanozolol in environmental waters using liquid chromatography tandem mass spectrometry  

PubMed Central

Background Owing to frequent administration of a wide range of pharmaceutical products, various environmental waters have been found to be contaminated with pharmacologically active substances. For example, stanozolol, a synthetic anabolic steroid, is frequently misused for performance enhancement as well as for illegal growth promoting purposes in veterinary practice. Previously we reported stanozolol in hair samples collected from subjects living in Budapest. For this reason we initiated this study to explore possible environmental sources of steroid contamination. The aim of this study was to develop a method to monitor stanozolol in aqueous matrices using liquid chromatography tandem mass spectrometry (LC-MS/MS). Results Liquid-liquid extraction using pentane was found to be an efficient method for the extraction of stanozolol from water samples. This was followed by direct detection using LC-MS/MS. The method was capable of detecting 0.25 pg/mL stanozolol when only 5 mL water was processed in the presence of stanozolol D3 as internal standard. Fifteen bottled waters analysed were found to be negative for stanozolol. However, three out of six samples from the Danube river, collected from December '09 to November '10, were found to contain stanozolol at concentrations up to 1.82 pg/mL. In contrast, only one sample (out of six) of urban tap water from Budapest city was found to contain stanozolol, at a concentration of 1.19 pg/mL. Conclusion The method developed is efficient, rapid, reproducible, sensitive and robust for the detection of stanozolol in aqueous matrices.

2011-01-01

380

Liquid chromatographic determination of ampicillin in bovine and dog plasma by using a tandem solid-phase extraction method.  

PubMed Central

The determination of ampicillin in plasma and serum by reversed-phase high-performance liquid chromatography with UV detection suffers from poor selectivity and sensitivity. Currently, the most common approach to overcoming these problems consists of improving the compound's detectability via pre- or postcolumn derivatization. In the method that we describe, however, enhanced selectivity is afforded by sample purification by a tandem solid-phase extraction method (ion-exchange and reversed-phase). This approach permits detection at wavelengths of as low as 210 nm, which results in enhanced sensitivity (detection limit, 0.01 microgram/ml). A second factor that affects selectivity is the addition to the chromatographic eluent of a crown ether to optimize the separation between ampicillin and polar endogenous plasma constituents. This combination of improved sample pretreatment and a more selective chromatographic system in conjunction with internal standardization forms the basis of a new assay for the quantitation of ampicillin in plasma. The overall recovery of ampicillin was 76.4% +/- 4.9% (n = 24), and the within-run and between-run coefficients of variation ranged from 1.6 to 7.2%. The method was applied to pharmacokinetic studies in cows and dogs after intramuscular or oral administration of the drug.

Nelis, H J; Vandenbranden, J; Verhaeghe, B; De Kruif, A; Mattheeuws, D; De Leenheer, A P

1992-01-01

381

Wavelength-transparent nonlinear optical gate based on self-seeded gain modulation in folded tandem-SOA  

Microsoft Academic Search

In this paper, an all-optical nonlinear gate employing a folded tandem-SOA structure is proposed. With a partial reflection mirror for the amplified signal, we achieve a self-seeded gain modulation effect in the folded tandem-SOA, thus eliminating an external saturating source required for the conventional tandem-SOA optical gate. The performance analysis of the proposed device as a 2R regenerator \\/ logic

Young Jin Jung

2007-01-01

382

Novel Tandem Biotransformation Process for the Biosynthesis of a Novel Compound, 4-(2,3,5,6-Tetramethylpyrazine-1)-4?-Demethylepipodophyllotoxin?  

PubMed Central

According to the structure of podophyllotoxin and its structure-function relationship, a novel tandem biotransformation process was developed for the directional modification of the podophyllotoxin structure to directionally synthesize a novel compound, 4-(2,3,5,6-tetramethylpyrazine-1)-4?-demethylepipodophyllotoxin (4-TMP-DMEP). In this novel tandem biotransformation process, the starting substrate of podophyllotoxin was biotransformed into 4?-demethylepipodophyllotoxin (product 1) with the demethylation of the methoxyl group at the 4? position by Gibberella fujikuroi SH-f13, which was screened out from Shennongjia prime forest humus soil (Hubei, China). 4?-Demethylepipodophyllotoxin (product 1) was then biotransformed into 4?-demethylpodophyllotoxone (product 2) with the oxidation of the hydroxyl group at the 4 position by Alternaria alternata S-f6, which was screened out from the gathered Dysosma versipellis plants in the Wuhan Botanical Garden, Chinese Academy of Sciences. Finally, 4?-demethylpodophyllotoxone (product 2) and ligustrazine were linked with a transamination reaction to synthesize the target product 4-TMP-DMEP (product 3) by Alternaria alternata S-f6. Compared with podophyllotoxin (i.e., a 50% effective concentration [EC50] of 529 ?M), the EC50 of 4-TMP-DMEP against the tumor cell line BGC-823 (i.e., 0.11 ?M) was significantly reduced by 5,199 times. Simultaneously, the EC50 of 4-TMP-DMEP against the normal human proximal tubular epithelial cell line HK-2 (i.e., 0.40 ?M) was 66 times higher than that of podophyllotoxin (i.e., 0.006 ?M). Furthermore, compared with podophyllotoxin (i.e., log P = 0.34), the water solubility of 4-TMP-DMEP (i.e., log P = 0.66) was significantly enhanced by 94%. For the first time, the novel compound 4-TMP-DMEP with superior antitumor activity was directionally synthesized from podophyllotoxin by the novel tandem biotransformation process developed in this work.

Tang, Ya-Jie; Zhao, Wei; Li, Hong-Mei

2011-01-01

383

Tandem Mass Spectrometry of Modified and Platinated Oligoribonucleotides  

NASA Astrophysics Data System (ADS)

Therapeutic approaches for treatment of various diseases aim at the interruption of transcription or translation. Modified oligonucleotides, such as 2'- O-methyl- and methylphosphonate-derivatives, exhibit high resistance against cellular nucleases, thus rendering application for, e.g., antigene or antisense purposes possible. Other approaches are based on administration of cross-linking agents, such as cis-diamminedichloroplatinum(II) (cisplatin, DDP), which is still the most widely used anticancer drug worldwide. Due to the formation of 1,2-intrastrand cross links at adjacent guanines, replication of the double-strand is disturbed, thus resulting in significant cytotoxicity. Evidence for the gas-phase dissociation mechanism of platinated RNA is given, based on nano-electrospray ionization high-resolution multistage tandem mass spectrometry (MS n ). Confirmation was found by investigating the fragmentation pattern of platinated and unplatinated 2'-methoxy oligoribonucleotide hexamers and their corresponding methylphosphonate derivatives. Platinated 2'-methoxy oligoribonucleotides exhibit a similar gas-phase dissociation behavior as the corresponding DNA and RNA sequences, with the 3'-C-O bond adjacent to the vicinal guanines being cleaved preferentially, leading to wx-ion formation. By examination of the corresponding platinated methylphosphonate derivatives of the 2'-methoxy oligoribonucleotides, the key role of the negatively charged phosphate oxygen atoms in direct proximity to the guanines was proven. The significant alteration of fragmentation due to platination is demonstrated by comparison of the fragment ion patterns of unplatinated and platinated 2'- O-methyl- and 2'- O-methyl methylphosphonate oligoribonucleotides, and the results obtained by H/D exchange experiments.

Nyakas, Adrien; Stucki, Silvan R.; Schürch, Stefan

2011-05-01

384

Revisiting hyper- and hypo-androgenism by tandem mass spectrometry.  

PubMed

Modern endocrinology is living a critical age of transition as far as laboratory testing and biochemical diagnosis are concerned. Novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for steroid measurement in biological fluids have abundantly demonstrated their analytical superiority over immunometric platforms that until now have dominated the world of steroid hormones determination in clinical laboratories. One of the most useful applications of LC-MS/MS is in the hypogonadism and hyperandrogenism field: LC-MS/MS has proved particularly suitable for the detection of low levels of testosterone typical of women and children, and in general more reliable in accurately determining hypogonadal male levels. This technique also offers increased informative power by allowing multi-analytical profiles that give a more comprehensive picture of the overall hormonal asset. Several LC-MS/MS methods for testosterone have been published in the last decade, some of them included other androgen or more comprehensive steroid profiles. LC-MS/MS offers the concrete possibility of achieving a definitive standardization of testosterone measurements and the generation of widely accepted reference intervals, that will set the basis for a consensus on the diagnostic value of biochemical testing. The present review is aimed at summarizing technological advancements in androgen measurements in serum and saliva. We also provide a picture of the state of advancement of standardization of testosterone assays, of the redefinition of androgen reference intervals by novel assays and of studies using LC-MS/MS for the characterization and diagnosis of female hyperandrogenism and male hypogonadism. PMID:23619762

Fanelli, Flaminia; Gambineri, Alessandra; Mezzullo, Marco; Vicennati, Valentina; Pelusi, Carla; Pasquali, Renato; Pagotto, Uberto

2013-06-01

385

Determination of dalcetrapib by liquid chromatography-tandem mass spectrometry.  

PubMed

The cholesteryl ester transfer protein modulator dalcetrapib is currently under development for the prevention of dyslipidemia and cardiovascular disease. Dalcetrapib, a thioester, is rapidly hydrolyzed in vivo to the corresponding thiophenol which in turn is further oxidized to the dimer and mixed disulfides (where the thiophenol binds to peptides, proteins and other endogenous thiols). These forms co-exist in an oxidation-reduction equilibrium via the thiol and cannot be stabilized without influencing the equilibrium, hence specific determination of individual components, i.e., in order to distinguish between the free thiol, the disulfide dimer and mixed disulfide adducts, was not pursued for routine analysis. The individual forms were quantified collectively as dalcetrapib-thiol (dal-thiol) after reduction under basic conditions with dithiothreitol to break disulfide bonds and derivatization with N-ethylmaleimide to stabilize the free thiol. The S-methyl and S-glucuronide metabolites were determined simultaneously with dal-thiol with no effect from the derivatization procedure. Column-switching liquid chromatography-tandem mass spectrometry provided a simple, fast and robust method for analysis of human and animal plasma and human urine samples. Addition of the surfactant Tween 80 to urine prevented adsorptive compound loss. The lower limits of quantitation (LLOQ) were 5 ng/mL for dal-thiol, and 5 ng/mL for the S-methyl and 50 ng/mL for the S-glucuronide metabolites. Using stable isotope-labeled internal standards, inter- and intra-assay precisions were each <15% (<20% at LLOQ) and accuracy was between 85 and 115%. Recovery was close to 100%, and no significant matrix effect was observed. PMID:22541249

Heinig, Katja; Bucheli, Franz; Kuhlmann, Olaf; Zell, Manfred; Pähler, Axel; Zwanziger, Elke; Gross, Günter; Tardio, Joseph; Ishikawa, Tomohiro; Yamashita, Tomoko

2012-04-06

386

TRStalker: an efficient heuristic for finding fuzzy tandem repeats  

PubMed Central

Motivation: Genomes in higher eukaryotic organisms contain a substantial amount of repeated sequences. Tandem Repeats (TRs) constitute a large class of repetitive sequences that are originated via phenomena such as replication slippage and are characterized by close spatial contiguity. They play an important role in several molecular regulatory mechanisms, and also in several diseases (e.g. in the group of trinucleotide repeat disorders). While for TRs with a low or medium level of divergence the current methods are rather effective, the problem of detecting TRs with higher divergence (fuzzy TRs) is still open. The detection of fuzzy TRs is propaedeutic to enriching our view of their role in regulatory mechanisms and diseases. Fuzzy TRs are also important as tools to shed light on the evolutionary history of the genome, where higher divergence correlates with more remote duplication events. Results: We have developed an algorithm (christened TRStalker) with the aim of detecting efficiently TRs that are hard to detect because of their inherent fuzziness, due to high levels of base substitutions, insertions and deletions. To attain this goal, we developed heuristics to solve a Steiner version of the problem for which the fuzziness is measured with respect to a motif string not necessarily present in the input string. This problem is akin to the ‘generalized median string’ that is known to be an NP-hard problem. Experiments with both synthetic and biological sequences demonstrate that our method performs better than current state of the art for fuzzy TRs and that the fuzzy TRs of the type we detect are indeed present in important biological sequences. Availability: TRStalker will be integrated in the web-based TRs Discovery Service (TReaDS) at bioalgo.iit.cnr.it. Contact: marco.pellegrini@iit.cnr.it Supplementary information: Supplementary data are available at Bioinformatics online.

Pellegrini, Marco; Renda, M. Elena; Vecchio, Alessio

2010-01-01

387

Flow and noise predictions for the tandem cylinder aeroacoustic benchmark  

NASA Astrophysics Data System (ADS)

Flow and noise predictions for the tandem cylinder benchmark are performed using lattice Boltzmann and Ffowcs Williams-Hawkings methods. The numerical results are compared to experimental measurements from the Basic Aerodynamic Research Tunnel and Quiet Flow Facility (QFF) at NASA Langley Research Center. The present study focuses on two configurations: the first configuration corresponds to the typical setup with uniform inflow and spanwise periodic boundary condition. To investigate installation effects, the second configuration matches the QFF setup and geometry, including the rectangular open jet nozzle, and the two vertical side plates mounted in the span to support the test models. For both simulations, the full span of 16 cylinder diameters is simulated, matching the experimental dimensions. Overall, good agreement is obtained with the experimental surface data, flow field, and radiated noise measurements. In particular, the presence of the side plates significantly reduces the excessive spanwise coherence observed with periodic boundary conditions and improves the predictions of the tonal peak amplitude in the far-field noise spectra. Inclusion of the contributions from the side plates in the calculation of the radiated noise shows an overall increase in the predicted spectra and directivity, leading to a better match with the experimental measurements. The measured increase is about 1 to 2 dB at the main shedding frequency and harmonics, and is likely caused by reflections on the spanwise side plates. The broadband levels are also slightly higher by about 2 to 3 dB, likely due to the shear layers from the nozzle exit impacting the side plates.

Brès, Guillaume A.; Freed, David; Wessels, Michael; Noelting, Swen; Pérot, Franck

2012-03-01

388

Functional ?-propeller lectins by tandem duplications of repetitive units.  

PubMed

Internal symmetry in proteins is likely to be the footprint of evolution by gene duplication and fusion. Like other symmetrical proteins, ?-propellers, which are made of 4-10 ?-sheet units (blades) circularly arranged around a central tunnel, have probably evolved by duplication and fusion of a rudimentary repetitive unit. However, reproducing the evolution of functional ?-propellers by duplication and fusion of repeated units remains a challenge, in particular, because the repeated units must jointly pack to form one hydrophobic core while maintaining intact active sites. As model for generating repeat propellers, we chose tachylectin-2--a highly symmetrical five-bladed ?-propeller lectin with five sugar-binding sites. We report the engineering of folded and functional lectins by duplication and fusion of repetitive sequence modules taken from tachylectin-2. The repeated modules comprise three strands of one blade plus one strand of the next blade, thus enabling the closure of the propeller's ring via strand-strand Velcro-like interactions. Duplication and fusion of five modules with the same sequence gave rise to a highly aggregated protein, yet its soluble fraction exhibited lectin function. Subsequently, a library of diversified sequence modules fused in tandem was selected by phage display for glycoprotein binding. A range of new lectins were isolated with binding and biophysical properties that resemble those of wild-type tachylectin-2. These results demonstrate the ability to construct folded and functional globular repeat proteins, and support the role of duplication and fusion of elementary modules in the evolutionary routes that led to the ?-propellers fold. PMID:20713410

Yadid, Itamar; Tawfik, Dan S

2010-08-16

389

Tandem solar cells deposited using hot-wire chemical vapor deposition  

NASA Astrophysics Data System (ADS)

In this thesis, the application of the hot-wire chemical vapor deposition (HWCVD) technique for the deposition of silicon thin films is described. The HWCVD technique is based on the dissociation of silicon-containing gasses at the catalytic surface of a hot filament. Advantages of this technique are the high deposition rate, the low equipment costs, and the scalability. The main goal of this thesis is the optimization of the material properties of both hydrogenated amorphous silicon and microcrystalline silicon, so that these materials can be incorporated as the absorbing layers in tandem solar cells. Firstly, the influence of specific deposition parameters on the material quality of hydrogenated amorphous silicon was investigated. With the use of tantalum filaments, the deposition temperature could be decreased to moderate temperatures, while the (electronic) properties of the amorphous silicon were improved. However, at these low filament temperatures the silicide formation at the filaments was enhanced, resulting in a decrease in the deposition rate and a deterioration of the material quality over time. For extensive silicide formation, even epitaxial growth on crystalline wafers was observed. By preheating the filaments at elevated temperature before deposition, the influence of silicide formation could be minimized, which resulted in an improvement in the reproducibility of the material quality. Solar cells, in which the absorbing layer was made at moderate temperature, had high open-circuit voltages and high fill factors. The best n-i-p structured cell on plain stainless steel had an initial efficiency of 7.2 %. The incorporation of amorphous silicon in p-i-n structured cells with a textured front contact resulted in a higher short-circuit current density and a higher efficiency. Occasionally, many n-i-p structured cells showed shunting problems. The number of working cells was directly correlated to the age of the filaments. The presence of silicides on the wires resulted in a deterioration of the material quality and in the formation of shunting paths. By annealing the filaments before deposition, most silicon was evaporated from the filaments, and its influence was minimized. Furthermore, the incorporation of a buffer layer between the n- and i-layer resulted in a change of the sticking probability of adverse radicals and a reduced formation of shunting paths. Next, the influence of the hydrogen dilution of the silane gas on the material properties of microcrystalline silicon was investigated. Crystalline growth occurred at high hydrogen dilutions. Different microcrystalline layers were incorporated as the absorbing layer in n-i-p structured solar cells. The best cells were made with material that was deposited at the edge of the transition from the microcrystalline to the amorphous regime. The best cell had an initial efficiency of 4.8 %. Furthermore, the applicability of the HWCVD technique for the deposition of microcrystalline n-doped layers was investigated. The material with the highest conductivity was deposited at moderate temperature, using a high hydrogen dilution. Application of these n-layers in n-i-p structured solar cells resulted in similar open- circuit voltages, but lower short-circuit current densities compared to solar cells with a plasma-enhanced deposited n-layer. Further optimization of the hot-wire n-layers is necessary. Finally, the different intrinsic layers were incorporated in tandem solar cells. It was possible to obtain high open-circuit voltages and high fill factors. Spectral response measurements of n-i-p/n-i-p structured solar cells indicated that a low photocurrent easily leaked through the bottom cell, which did not occur in p-i-n/p-i-n cells. Apparently, the order in which the p- and n-layer in the tunnel-recombination junction were deposited influenced this small leakage effect. This junction needs further optimization in n-i-p structured tandem solar cells. Based on the achieved efficiencies for amorphous and microcrystalline solar cells on untextured stainless steel, effic

van Veen, M. K.

2003-05-01

390

Synthesis and conformational investigation of tandem repeat sequence in RNA polymerase II.  

PubMed

The largest subunit of RNA polymerase II has a very interesting sequence in the C-terminus; that is, a tandem repeat sequence of Ser-Pro-Thr-Ser-Pro-Ser-Tyr consisted of proline residues and three kinds of residues having side-chain hydroxyl groups. Although lack of this tandem repeat is a lethal event in vivo, its functional role is unclear. The sequential polypeptide corresponding to this tandem repeat, poly(Ser-Pro-Thr-Ser-Pro-Ser-Tyr), was synthesized and its conformation was investigated by circular dichroism comparing to the monomeric heptapeptide. In addition, the theoretical conformational analysis based on the molecular mechanics was tried for the heptapeptide in the repeating unit and the periodic polyheptapeptide corresponding to the tandem repeat sequence. These results suggested the possibility that the tandem repeat contains a kind of super conformation composed of the repetitive turn structure in the native state. The characteristic repetitive turn structure would be the key of its function mechanism. PMID:7832814

Nishi, N; Ohiso, I; Sakairi, N; Tokura, S; Tsunemi, M; Oka, M

1995-01-26

391

Performance Characteristics of Tandem-Structure Fans for Redundant Cooling of Electronic Equipment  

NASA Astrophysics Data System (ADS)

We have measured the fan performance characteristics and sound pressure level of tandem fans suitable for redundant cooling systems of electronic equipment. Maximum static pressure of tandem fans without flow-regulate-plate is 1.5 time of single fan at no fan spacing. It increases with fan spacing and reaches 1.9 time at fan spacing of 400 mm. Maximum static pressure of tandem fans with flow-regulate-plate which is symmetrical to the axis of fans is about 1.9 to 2.0 times of single fan, and it dose not affected by fan spacing. Improvement of performance characteristics is larger with longer flow-regulate-plate that is slightly shorter than fan spacing. For example, the plate length of 75 mm is found to be almost optimum for fan spacing of 100 mm. When one of the tandem fans is stopped, performance characteristics is about 80 to 90 % of single fan, and rotational speed of stopped fan is almost proportional to the volume flow rate of operating fan. Sound pressure level of tandem fans without load at normal operating condition is reduced by nearly 8 dB at maximum by changing fan spacing from 0 mm to 300 mm.

Matsushima, Hitoshi; Fukuda, Hiroshi

392

Ab initio detection of fuzzy amino acid tandem repeats in protein sequences  

PubMed Central

Background Tandem repetitions within protein amino acid sequences often correspond to regular secondary structures and form multi-repeat 3D assemblies of varied size and function. Developing internal repetitions is one of the evolutionary mechanisms that proteins employ to adapt their structure and function under evolutionary pressure. While there is keen interest in understanding such phenomena, detection of repeating structures based only on sequence analysis is considered an arduous task, since structure and function is often preserved even under considerable sequence divergence (fuzzy tandem repeats). Results In this paper we present PTRStalker, a new algorithm for ab-initio detection of fuzzy tandem repeats in protein amino acid sequences. In the reported results we show that by feeding PTRStalker with amino acid sequences from the UniProtKB/Swiss-Prot database we detect novel tandemly repeated structures not captured by other state-of-the-art tools. Experiments with membrane proteins indicate that PTRStalker can detect global symmetries in the primary structure which are then reflected in the tertiary structure. Conclusions PTRStalker is able to detect fuzzy tandem repeating structures in protein sequences, with performance beyond the current state-of-the art. Such a tool may be a valuable support to investigating protein structural properties when tertiary X-ray data is not available.

2012-01-01

393

Generation of tandem direct duplications by reversed-ends transposition of maize ac elements.  

PubMed

Tandem direct duplications are a common feature of the genomes of eukaryotes ranging from yeast to human, where they comprise a significant fraction of copy number variations. The prevailing model for the formation of tandem direct duplications is non-allelic homologous recombination (NAHR). Here we report the isolation of a series of duplications and reciprocal deletions isolated de novo from a maize allele containing two Class II Ac/Ds transposons. The duplication/deletion structures suggest that they were generated by alternative transposition reactions involving the termini of two nearby transposable elements. The deletion/duplication breakpoint junctions contain 8 bp target site duplications characteristic of Ac/Ds transposition events, confirming their formation directly by an alternative transposition mechanism. Tandem direct duplications and reciprocal deletions were generated at a relatively high frequency (?0.5 to 1%) in the materials examined here in which transposons are positioned nearby each other in appropriate orientation; frequencies would likely be much lower in other genotypes. To test whether this mechanism may have contributed to maize genome evolution, we analyzed sequences flanking Ac/Ds and other hAT family transposons and identified three small tandem direct duplications with the structural features predicted by the alternative transposition mechanism. Together these results show that some class II transposons are capable of directly inducing tandem sequence duplications, and that this activity has contributed to the evolution of the maize genome. PMID:23966872

Zhang, Jianbo; Zuo, Tao; Peterson, Thomas

2013-08-15

394

Dextroamphetamine Enhances \\  

Microsoft Academic Search

Previous studies in animals and humans suggest that mono- amines enhance behavior-evoked neural activity relative to nonspecific background activity (i.e., increase signal-to-noise ratio). We studied the effects of dextroamphetamine, an indirect monoaminergic agonist, on cognitively evoked neural activity in eight healthy subjects using positron-emission tomography and the O15 water intravenous bolus method to measure re- gional cerebral blood flow (rCBF).

Venkata S. Mattay; Karen Faith Berman; Jill L. Ostrem; Giuseppe Esposito; John D. Van Horn; Llewellyn B. Bigelow; Daniel R. Weinberger

1996-01-01

395

Positional enhancer-blocking activity of the chicken ?-globin insulator in transiently transfected cells  

PubMed Central

It is thought that insulators demarcate transcriptionally and structurally independent chromatin domains. Insulators are detected by their ability to block enhancer–promoter interactions in a directional manner, and protect a transgene from position effects. Most studies are performed in stably transformed cells or organisms. Here we analyze the enhancer-blocking activity of the chicken ?-globin insulator in transient transfection experiments in both erythroid and nonerythroid cell lines. We show that four tandem copies of a 90-bp fragment of this insulator were able to block an enhancer in these experiments. In circular plasmids, placement on either side of the enhancer reduced activity, but when the plasmid was linearized, the enhancer-blocking activity was observed only when the insulator was placed between the promoter and the enhancer. These observations are consistent with the position-dependent enhancer-blocking activity of the insulator observed in stable transformation experiments.

Recillas-Targa, Felix; Bell, Adam C.; Felsenfeld, Gary

1999-01-01

396

Influence of H2O/DEZ ratio on LPCVD ZnO:B films for application in a-Si:H/?c-Si:H tandem solar cells  

NASA Astrophysics Data System (ADS)

In this study, boron doped zinc oxide (ZnO:B) films were prepared at different water to diethyl zinc (H2O/DEZ) flow ratios from 0.6 to 1.4 by a low pressure chemical vapor deposition (LPCVD) technique. It is found that the morphology of ZnO:B films varies from small leaf-like to pyramidal surface structures with the increasing H2O/DEZ flow ratio. The rough ZnO:B films deposited at a relatively H2O/DEZ flow ratio such as 1.2 or 1.4 show a high haze value of up to 28 % at 600 nm and a (11overline{2}0) preferential crystallographic orientation. All ZnO:B films were applied in hydrogenated amorphous silicon/microcrystalline silicon tandem solar cells (a-Si:H/?c-Si:H) as front electrodes. The efficiency of the solar cells increases with the increasing H2O/DEZ flow ratio, which is attributed to a high spectral response mainly in the long-wavelength range and the consequent enhancement of short-circuit current. A high-efficiency a-Si:H/?c-Si:H tandem solar cell of 10 % was achieved. The H2O/DEZ ratio is an important process parameter to tune the material properties of LPCVD ZnO:B films and the performances of corresponding silicon thin film solar cells.

Wan, M.; Zhu, H.; Wang, Y.; Yin, J.; Gao, J.; Wang, Z.; Guan, F.; Mai, Y.; Huang, Y.; Yu, W.; Huang, S.

2013-06-01

397

Mouse-Specific Tandem IgY7-SuperMix Immunoaffinity Separations for Improved LC-MS/MS Coverage of the Plasma Proteome  

SciTech Connect

We report on a customized mouse specific SuperMix immunoaffinity column and strategy for separating low abundance proteins from high and moderate abundance proteins in mouse plasma. When applied in tandem with a mouse IgY7 column that removes the seven most abundant proteins in blood, the SuperMix column captures >100 additional moderate abundance proteins, thus allowing significant enrichment of low abundance proteins in the flow-through fraction. A side-by-side comparison of results obtained from 2D-LC-MS/MS analyses of flow-through samples from IgY7 and SuperMix columns revealed a nearly two-fold improvement in the overall proteome coverage. Detection of low abundance proteins was also enhanced, as evidenced by a more than two-fold increase in the coverage of cytokines, growth factors, and other low abundance proteins. Moreover, the tandem separations are automated, reproducible, and allow effective identification of protein abundance differences from LC-MS/MS analyses. Considering the overall reproducibility and increased sensitivity using the IgY7-SuperMix separation system, we anticipate broad applications of this strategy for biomarker discovery using mouse models.

Zhou, Jianying; Petritis, Brianne O.; Petritis, Konstantinos; Norbeck, Angela D.; Weitz, Karl K.; Moore, Ronald J.; Camp, David G.; Kulkarni, Rohit N.; Smith, Richard D.; Qian, Weijun

2009-09-01

398

Development and validation of a simple and sensitive liquid chromatography-tandem mass spectrometry method for quantifying trimetazidine in human plasma.  

PubMed

1. A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for quantifying trimetazidine in human plasma was developed and validated. Sample preparation was based on deproteinating with acetonitrile. 2. Chromatography was performed on a C18 analytical column (5 mum; 150 x 2.1 mm i.d.) and the retention times for trimetazidine and cetirizine (used as the internal standard) were 1.8 and 3.0 min, respectively. The ionization was optimized using an electrospray ionization source and enhanced selectivity was achieved using tandem mass spectrometry. The calibration curve ranged from 0.1 to 200 ng/mL. The inter-day precision, accuracy and the relative standard deviation (RSD) were all < 15%. The analyte was shown to be stable over the time-scale of the entire procedure. 3. The robustness of the method was demonstrated by the good reproducibility of the results obtained during the analysis of clinical samples. PMID:19878214

Zhou, Gan; Tan, Zhi-Rong; Ouyang, Dong-Sheng; Chen, Yao; Guo, Dong; Xie, Hai-Tang; Liu, Ying-Zi; Fan, Lan; Deng, Han-Wu

2009-10-29

399

Tandem ChoRE and CCAAT Motifs and Associated Factors Regulate Txnip Expression in Response to Glucose or Adenosine-Containing Molecules  

PubMed Central

Background Thioredoxin interacting protein (Txnip) is a multifunctional protein involved in regulation of cell cycle events and cellular metabolism. The expression of Txnip is known to be induced by glucose, adenosine-containing molecules, and other physiological cues; however, the underlying regulatory mechanisms remain elusive. Methodology/Principal Findings In this study, using promoter reporter, electrophoresis mobility shift (EMSA), and chromatin immuno-precipitation (ChIP) assays, we have identified an additional carbohydrate response element (ChoRE) on the promoter of Txnip gene, which functions cooperatively with the earlier identified ChoRE to mediate optimal Txnip expression. However, these two ChoREs are not sufficient to mediate the induction of Txnip expression by glucose or adenosine-containing molecules; and two CCAAT boxes, both of which can recruit nuclear factor Y (NF-Y) to the Txnip promoter, are also required for the induction. Accordingly, we have found that the function of ChoREs and associated factors is contingent on tandem CCAAT boxes, in that occupancy of the Txnip promoter by NF-Y is a prerequisite for efficacious recruitment of Mondo/MLX to ChoREs under glucose stimulation. Conclusions/Significance Our findings suggest a synergy between the tandem CCAAT and ChoRE motifs and associated NF-Y and Mondo/MLX transcription factors in enhancing transcription from the Txnip promoter. This piece of information will be helpful for future dissection of molecular mechanisms governing the transcriptional regulation of Txnip, a glucose responsive gene.

Yu, Fa-Xing; Luo, Yan

2009-01-01

400

Collision-induced dissociation tandem mass spectrometry for structural elucidation of glycans.  

PubMed

The complexity of glycans poses a major challenge for structure elucidation. Tandem mass spectrometry is currently an efficient and powerful technique for the structural characterization of glycans. Collision-induced dissociation (CID) is most commonly used, and involves first isolating the glycan ions of interest, translationally exciting them, and then striking them with inert target gas to fragment the precursor ions. The structural information of the glycan can be obtained from the fragment ions of the tandem MS spectra. In this chapter, sustained off-resonance irradiation-collision-induced dissociation (SORI-CID) implemented with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT ICR MS) is demonstrated to be a useful analysis tool for structural elucidation of mucin-type O-glycans released from mucin glycoproteins. The mechanisms by which the glycans undergo fragmentations in the tandem mass analysis are also discussed. PMID:19277555

Li, Bensheng; An, Hyun Joo; Hedrick, Jerry L; Lebrilla, Carlito B

2009-01-01

401

Rapidly convergent algorithms for 3-D tandem and stellarator equilibria in the paraxial approximation  

SciTech Connect

Tandem and stellarator equilibria at high ..beta.. have proved hard to compute and the relaxation methods of Bauer et al., Chodura and Schluter, Hirshman, Strauss, and Pearlstein et al. have been slow to converge. This paper reports an extension of the low-..beta.. analytic method of Pearlstein, Kaiser, and Newcomb to arbitrary ..beta.. for tandem mirrors which converges in 10 to 20 iterations. Extensions of the method to stellarator equilibria are proposed and are very close to the analytic method of Johnson and Greene - the stellarator expansion. Most of the results of all these calculations can be adequately described by low-..beta.. approximations since the MHD stability limits occur at low ..beta... The tandem mirror, having weak curvature and a long central cell, allows finite Larmor radius effects to eliminate most ballooning modes and offers the possibility of really high average ..beta... This is the interest in developing such three-dimensional numerical algorithms.

McNamara, B.

1984-04-01

402

Indian isolates of white spot syndrome virus exhibit variations in their pathogenicity and genomic tandem repeats.  

PubMed

To detect genomic variation of white spot syndrome virus (WSSV) isolates from different geographical regions of India, the variable number of the tandem repeat (VNTR) region of the ORF 94 (Thailand WSSV isolate - GeneBank Accession No. AF369029) was analysed using five specific sets of primers. Analysis of 70 WSSV-positive samples showed the presence of 14 different genotypes of WSSV with VNTRs ranging from 2 to 16 tandem repeats with the majority (85.47%) having 6-12 tandem repeats. Occurrence of different genotypes of WSSV was found to be neither correlated to any specific geographical region nor to the different growth stage of the tiger shrimp, Penaeus monodon. Pathogenicity studies conducted with 25 isolates of WSSV revealed the presence of virulent and avirulent strains of WSSV in Indian shrimp farms. However, an unambiguous link could not be established between the different genotypes and their virulence. PMID:20690959

John, K R; George, M R; Iyappan, T; Thangarani, A J; Jeyaseelan, M J P

2010-09-01

403

Throughput analysis of tandem-type go-back-N ARQ scheme for satellite communications  

NASA Astrophysics Data System (ADS)

The tandem-type go-back-N (GBN) scheme has been proposed for satellite communications to reduce the long roundtrip delay using the on-board processing of satellites. In this paper, we consider the exact analysis of the throughput performance of this scheme and its application to a broadcast communications system such as a point-to-multipoint file transfer system. First, the throughput expression for the point-to-point tandem-type GBN scheme is derived. Second, applying the results of this point-to-point tandem-type GBN scheme to a broadcast (point-to-multipoint) communications system, the relationship of the number of receiving stations to the link bit error rate and the roundtrip propagation delay is shown.

Hayashida, Yukuo

1993-10-01

404

Lattice-Matched GaNPAs-On-Silicon Tandem Solar Cells  

SciTech Connect

A two-junction device consisting of a 1.7-eV GaNPAs junction on a 1.1-eV silicon junction has the theoretical potential to achieve nearly optimal efficiency for a two-junction tandem cell. We have demonstrated a monolithic III-V-on-silicon tandem solar cell in which most of the III-V layers are nearly lattice-matched to the silicon substrate. The cell includes a 1.8 eV GaNPAs top cell, a GaP-based tunnel junction (TJ), and a diffused silicon junction formed during the epitaxial growth of GaNP on the silicon substrate. This tandem on silicon has a Voc of 1.53 V and an AM1.5G efficiency of 5.2% without any antireflection coating. Low currents in the top cell are the primary limitation to higher efficiency at this point.

Geisz, J. F.; Olson, J. M.; Friedman, D. J.; Jones, K. M.; Reedy, R. C.; Romero, M. J.

2005-02-01

405

Analysis of tandem DNA repeats of cottoid fish in Lake Baikal by direct consensus sequencing.  

PubMed

This paper presents a simple method of consensus sequencing of monomeric repeat units during a single sequencing procedure by the example of a recently found BspMII family of tandemly arrayed repeats of Baikal cottoid fish (Cottoidei). This approach is based on obtaining multimeric repeat forms by the polymerase chain reaction, which eliminates the need of cloning and significantly simplifies the use of tandem repeats in phylogenetic studies. An attempt has been made to derive a phylogenetic evolution pattern of the In1 element of BspMII repeats for eight cottoid species of Lake Baikal. The position of two golomyanka species (Comephorus dybowskii and Comephorus baicalensis) on a phylogenetic tree confirms the theory of their relatively recent origin, based on mitochondrial cytochrome b gene analysis. It was estimated that the tandem repeat element In1 evolves at least one order of magnitude faster than genome coding sequences. PMID:7704113

Slobodyanyuk SYu; Pavlova, M E; Belikov, S I

1994-12-01

406

Total therapy with tandem transplants for newly diagnosed multiple myeloma.  

PubMed

Between August 1990 and August 1995, 231 patients (median age 51, 53% Durie-Salmon stage III, median serum beta-2-microglobulin 3.1 g/L, median C-reactive protein 4 g/L) with symptomatic multiple myeloma were enrolled in a program that used a series of induction regimens and two cycles of high-dose therapy ("Total Therapy"). Remission induction utilized non-cross-resistant regimens (vincristine-doxorubicin-dexamethasone [VAD], high-dose cyclophosphamide and granulocyte-macrophage colony-stimulating factor with peripheral blood stem cell collection, and etoposide-dexamethasone-cytarabine-cisplatin). The first high-dose treatment comprised melphalan 200 mg/m2 and was repeated if complete (CR) or partial (PR) remission was maintained after the first transplant; in case of less than PR, total body irradiation or cyclophosphamide was added. Interferon--2b maintenance was used after the second autotransplant. Fourteen patients with HLA-compatible donors underwent an allograft as their second high-dose therapy cycle. Eighty-eight percent completed induction therapy whereas first and second transplants were performed in 84% and 71% (the majority within 8 and 15 months, respectively). Eight patients (3%) died of toxicity during induction, and 2 (1%) and 6 (4%) during the two transplants. True CR and at least a PR (PR plus CR) were obtained in 5% (34%) after VAD, 15% (65%) at the end of induction, and 26% (75%) after the first and 41% (83%) after the second transplants (intent-to-treat). Median overall (OS) and event-free (EFS) survival durations were 68 and 43 months, respectively. Actuarial 5-year OS and EFS rates were 58% and 42%, respectively. The median time to disease progression or relapse was 52 months. Among the 94 patients achieving CR, the median CR duration was 50 months. On multivariate analysis, superior EFS and OS were observed in the absence of unfavorable karyotypes (11q breakpoint abnormalities, -13 or 13-q) and with low beta-2-microglobulin at diagnosis. CR duration was significantly longer with early onset of CR and favorable karyotypes. Time-dependent covariate analysis suggested that timely application of a second transplant extended both EFS and OS significantly, independent of cytogenetics and beta-2-microglobulin. Total Therapy represents a comprehensive treatment approach for newly diagnosed myeloma patients, using multi-regimen induction and tandem transplantation followed by interferon maintenance. As a result, the proportion of patients attaining CR increased progressively with continuing therapy. This observation is particularly important because CR is a sine qua non for long-term disease control and, eventually, cure. PMID:9864146

Barlogie, B; Jagannath, S; Desikan, K R; Mattox, S; Vesole, D; Siegel, D; Tricot, G; Munshi, N; Fassas, A; Singhal, S; Mehta, J; Anaissie, E; Dhodapkar, D; Naucke, S; Cromer, J; Sawyer, J; Epstein, J; Spoon, D; Ayers, D; Cheson, B; Crowley, J

1999-01-01

407

Analysis of isoaspartate in peptides by electrospray tandem mass spectrometry.  

PubMed Central

In view of the significance of Asn deamidation and Asp isomerization to isoAsp at certain sites for protein aging and turnover, it was desirable to challenge the extreme analytical power of electrospray tandem mass spectrometry (ESI-MS/MS) for the possibility of a site-specific detection of this posttranslational modification. For this purpose, synthetic L-Asp/L-isoAsp containing oligopeptide pairs were investigated by ESI-MS/MS and low-energy collision-induced dissociation (CID). Replacement of L-Asp by L-isoAsp resulted in the same kind of shifts for all 15 peptide pairs investigated: (1) the b/y intensity ratio of complementary b and y ions generated by cleavage of the (L-Asp/L-isoAsp)-X bond and of the X-(L-Asp/L-isoAsp) bond was decreased, and (2) the Asp immonium ion abundance at m/z 88 was also decreased. It is proposed that the isoAsp structure hampers the accepted mechanism of b-ion formation on both its N- and C-terminal side. The b/y ion intensity ratio and the relative immonium ion intensity vary considerably, depending on the peptide sequence, but the corresponding values are reproducible when recorded on the same instrument under identical instrumental settings. Thus, once the reference product ion spectra have been documented for a pair of synthetic peptides containing either L-Asp or L-isoAsp, these identify one or the other form. Characterization and relative quantification of L-Asp/L-isoAsp peptide mixtures are also possible as demonstrated for two sequences for which isoAsp formation has been described, namely myrG-D/isoD-AAAAK (deamidated peptide 1-7 of protein kinase A catalytic subunit) and VQ-D/isoD-GLR (deamidated peptide 41-46 of human procollagen alpha 1). Thus, the analytical procedures described may be helpful for the identification of suspected Asn deamidation and Asp isomerization sites in proteolytic digests of proteins.

Lehmann, W. D.; Schlosser, A.; Erben, G.; Pipkorn, R.; Bossemeyer, D.; Kinzel, V.

2000-01-01

408

Short Tandem Repeats in Human Exons: A Target for Disease Mutations  

PubMed Central

Background In recent years it has been demonstrated that structural variations, such as indels (insertions and deletions), are common throughout the genome, but the implications of structural variations are still not clearly understood. Long tandem repeats (e.g. microsatellites or simple repeats) are known to be hypermutable (indel-rich), but are rare in exons and only occasionally associated with diseases. Here we focus on short (imperfect) tandem repeats (STRs) which fall below the radar of conventional tandem repeat detection, and investigate whether STRs are targets for disease-related mutations in human exons. In particular, we test whether they share the hypermutability of the longer tandem repeats and whether disease-related genes have a higher STR content than non-disease-related genes. Results We show that validated human indels are extremely common in STR regions compared to non-STR regions. In contrast to longer tandem repeats, our definition of STRs found them to be present in exons of most known human genes (92%), 99% of all STR sequences in exons are shorter than 33 base pairs and 62% of all STR sequences are imperfect repeats. We also demonstrate that STRs are significantly overrepresented in disease-related genes in both human and mouse. These results are preserved when we limit the analysis to STRs outside known longer tandem repeats. Conclusion Based on our findings we conclude that STRs represent hypermutable regions in the human genome that are linked to human disease. In addition, STRs constitute an obvious target when screening for rare mutations, because of the relatively low amount of STRs in exons (1,973,844 bp) and the limited length of STR regions.

Madsen, Bo Eskerod; Villesen, Palle; Wiuf, Carsten

2008-01-01

409

Tandem repeat markers as novel diagnostic tools for high resolution fingerprinting of Wolbachia  

PubMed Central

Background Strains of the endosymbiotic bacterium Wolbachia pipientis are extremely diverse both genotypically and in terms of their induced phenotypes in invertebrate hosts. Despite extensive molecular characterisation of Wolbachia diversity, little is known about the actual genomic diversity within or between closely related strains that group tightly on the basis of existing gene marker systems, including Multiple Locus Sequence Typing (MLST). There is an urgent need for higher resolution fingerprinting markers of Wolbachia for studies of population genetics, horizontal transmission and experimental evolution. Results The genome of the wMel Wolbachia strain that infects Drosophila melanogaster contains inter- and intragenic tandem repeats that may evolve through expansion or contraction. We identified hypervariable regions in wMel, including intergenic Variable Number Tandem Repeats (VNTRs), and genes encoding ankyrin (ANK) repeat domains. We amplified these markers from 14 related Wolbachia strains belonging to supergroup A and were successful in differentiating size polymorphic alleles. Because of their tandemly repeated structure and length polymorphism, the markers can be used in a PCR-diagnostic multilocus typing approach, analogous to the Multiple Locus VNTR Analysis (MLVA) established for many other bacteria and organisms. The isolated markers are highly specific for supergroup A and not informative for other supergroups. However, in silico analysis of completed genomes from other supergroups revealed the presence of tandem repeats that are variable and could therefore be useful for typing target strains. Conclusions Wolbachia genomes contain inter- and intragenic tandem repeats that evolve through expansion or contraction. A selection of polymorphic tandem repeats is a novel and useful PCR diagnostic extension to the existing MLST typing system of Wolbachia, as it allows rapid and inexpensive high-throughput fingerprinting of closely related strains for which polymorphic markers were previously lacking.

2012-01-01

410

Tandemly duplicated upstream control sequences mediate copper-induced transcription of the Saccharomyces cerevisiae copper-metallothionein gene.  

PubMed Central

Transcription of the Saccharomyces cerevisiae copper-metallothionein gene, CUP1, inducible by copper. By analyzing deletion and fusion mutants in the CUP1 5'-flanking region, we identified two closely related, tandemly arranged copper regulatory elements. A synthetic version of one of these elements conferred efficient copper induction on a heterologous promoter when present in two tandem copies. Images

Thiele, D J; Hamer, D H

1986-01-01

411

Genetic Diversity of Typha latifolia (Typhaceae) and the Impact of Pollutants Examined with Tandem-Repetitive DNA Probes  

Microsoft Academic Search

Genetic diversity at variable-number-tandem-repeat (VNTR) loci was examined in the common cattail, Typha latifolia (Typhaceae), using three synthetic DNA probes composed of tandemly repeated ''core'' sequences (GACA, GATA, and GCAC). The principal objectives of this investigation were to determine whether: (1) the previously reported almost complete lack of polymorphism at allozyme loci in this species was indicative of a reduced

Brian Keane; Stephan Pelikan; Greg P. Toth; M. Kate Smith; Steven H. Rogstad

1999-01-01

412

Cavitation experiments with tandem propellers designed for large high speed cargo ship. Interim report October 1981March 1983  

Microsoft Academic Search

As part of a Maritime Administration project in energy conservation, the David Taylor Naval Ship Research and Development Center (DTNSRDC) has been tasked to design and evaluate a set of tandem propellers for a high-speed containership (Model 5218). This report presents the results of open water and cavitation experiments for these design tandem propellers. A conventional single propeller was also

1983-01-01

413

Catalytic asymmetric tandem Friedel-Crafts alkylation/Michael addition reaction for the synthesis of highly functionalized chromans.  

PubMed

The enantioselective tandem Friedel-Crafts alkylation/Michael addition reaction of indoles with nitroolefin enoates catalyzed by a diphenylamine-linked bis(oxazoline)-Zn(OTf)2 complex was investigated. This tandem reaction afforded functionalized chiral chromans in good yields with moderate to high stereoselectivities (up to 95:5 dr, up to 99% ee). PMID:23843916

Peng, Jiahuan; Du, Da-Ming

2013-06-24

414

Physics modeling of tandem mirror devices with high-field test cell inserts  

SciTech Connect

Recently developed plasma physics models of tandem mirror operation with a high-field technology test cell insert in the central cell are described in detail. These models have been incorporated in the TMRBAR tandem mirror reactor physics code. Results of a benchmark case for the code models against previous analysis of the MFTF - ..cap alpha.. /sup +/ T configuration are given. A brief users guide to the new TMRBAR with the test cell models is also presented. Some description of the applications of the models to MFTF - ..cap alpha.. /sup +/ T and FPD - II + T configurations is made. References are given to separate reports on these studies.

Fenstermacher, M.E.; Campbell, R.B.

1985-04-15

415

A statistical approach to peptide identification from clustered tandem mass spectrometry data  

PubMed Central

Tandem mass spectrometry experiments generate from thousands to millions of spectra. These spectra can be used to identify the presence of proteins in biological samples. In this work, we propose a new method to identify peptides, substrings of proteins, based on clustered tandem mass spectrometry data. In contrast to previously proposed approaches, which identify one representative spectrum for each cluster using traditional database searching algorithms, our method uses all available information to score all the spectra in a cluster against candidate peptides using Bayesian model selection. We illustrate the performance of our method by applying it to seven-standard-protein mixture data.

Ryu, Soyoung; Goodlett, David R.; Noble, William S.; Minin, Vladimir N.

2013-01-01

416

ECR (Electron Cyclotron Resonance) source for the HHIRF (Holifield Heavy Ion Research Facility) tandem accelerator  

SciTech Connect

Electron Cyclotron Resonance, ECR, ion source technology has developed rapidly since the original pioneering work of R. Geller and his group at Grenoble in the early 1970s. These ion sources are capable of producing intense beams of highly charged positive ions and are used extensively for cyclotron injection, linac injection, and atomic physics research. In this paper, the advantages of using an ECR heavy-ion source in the terminal of the Holifield Heavy Ion Research Facility (HHIRF) 25-MV tandem accelerator is discussed. A possible ECR system for installation in the HHIRF tandem terminal is described.

Olsen, D.K.; Alton, G.D.; Dowling, D.T.; Haynes, D.L.; Jones, C.M.; Juras, R.C.; Lane, S.N.; Meigs, M.J.; Mills, G.D.; Mosko, S.W.; Tatum, B.A.

1990-01-01

417

Benzodiazepines and metabolites from biological fluids by liquid chromatography electrospray tandem mass spectrometry.  

PubMed

Solid-phase extraction and liquid chromatography-tandem mass spectrometry are invaluable techniques for the determination of benzodiazepines and metabolites in biological matrices. The reason for using tandem mass spectrometry is to increase limits of detection without the need for chemical derivatization. Here we describe a technique for the detection of 26 benzodiazepines and metabolites at a detection limit of approximately 1-2 ng/mL in blood and 1-5 ng/mL in urine when screened using a data-dependent scan method. PMID:22767106

Morris-Kukoski, Cynthia L; Schaff, Jason E; Reda, Louis J

2012-01-01

418

Unexpected formation of 2,1-benzisothiazol-3-ones from oxathiolano ketenimines: a rare tandem process.  

PubMed

A rare one-pot reaction, a tandem [1,5]-H shift/1,5 electrocyclization/[3 + 2] cycloreversion process, leading from N-[2-(1,3-oxathiolan-2-yl)]phenyl ketenimines to 1-(beta-styryl)-2,1-benzisothiazol-3-ones and ethylene, is disclosed and mechanistically unraveled by means of a computational DFT study. The two latter stages of the tandem process are calculated to occur in a single mechanistic step via a transition structure of pseudopericyclic characteristics. PMID:19245248

Alajarin, Mateo; Bonillo, Baltasar; Sanchez-Andrada, Pilar; Vidal, Angel; Bautista, Delia

2009-03-19

419

GaInP[sub 2]/GaAs tandem cells: Problems and solutions  

SciTech Connect

The various factors that affect the open-circuit voltage ([ital V][sub oc]) of a two-terminal GaInP[sub 2]/GaAs tandem cell are examined. These include a) an anomalous problem associated with the GaAs bottom cell and b) back surface passivation of the thin GaInP[sub 2] top cell. Solutions to these problems are presented and yield tandem [ital V][sub oc]s close to the practical theoretical limits.

Friedman, D.J.; Kurtz, S.R.; Kibbler, A.E.; Olson, J.M. (National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States))

1992-12-01

420

Very high frequency plasma deposited amorphous/nanocrystalline silicon tandem solar cells on flexible substrates  

NASA Astrophysics Data System (ADS)

The work in this thesis is to develop high quality intrinsic layers (especially nc-Si:H) for micromorph silicon tandem solar cells/modules on plastic substrates following the substrate transfer method or knows as the Helianthos procedure. Two objectives are covered in this thesis: (1) preliminary work on trial and optimization of single junction and tandem cells on glass substrate, (2) silicon film depositions on Al foil, and afterwards the characterization and development of these cells/modules on a plastic substrate. The first objective includes the development of suitable ZnO:Al TCO for nc Si:H single junction solar cells, fabrication of the aimed micromorph tandem solar cells on glass, and finally the optimization of the nc-Si:H i-layer for the depositions afterwards on Al foil. Chapter 3 addresses the improvement of texture etching of ZnO:Al by studying the HCl etching effect on ZnO:Al films sputter-deposited in a set substrate heater temperature series. With the texture-etched ZnO:Al front TCO, a single junction nc-Si:H solar cell was deposited with an initial efficiency of 8.33%. Chapter 4 starts with studying the light soaking and annealing effects on micromorph tandem solar cell. In the end, a highly stabilized bottom cell current limited tandem cell was made. The tandem shows an initial efficiency of 10.2%, and degraded only 6.9% after 1600 h of light soaking. In Chapter 5, the nc-Si:H i-layers were studied in 3 pressure and inter-electrode distance series. The correlations between plasma physics and the consequent i-layers’ properties are investigated. We show that the Raman crystalline ratio and porosity of the nc-Si:H layer have an interesting relation with the p•d product. By varying p and d, device quality nc-Si:H layer can be deposited at a high rate of 0.6 nm/s. These results in fact are a very important step for the second objective. The second objective is covered by the entire Chapter 6. All silicon layers are deposited on special aluminum foils. Completed devices (including single junction a Si:H, nc-Si:H and micromorph silicon tandem cells/modules) on plastic substrates are characterized and discussed. In the end, 2.5 cm2 area micromorph tandem cells on foil were fabricated with an initial efficiency of the best cell to be 8.12% (FF = 0.64). After 1000 h of light soaking, its efficiency and FF degraded about 15% and 14.2% respectively.

Liu, Y.

2010-02-01

421

Plasma confinement experiments in the TMX tandem mirror. Paper IAEA-CN-38/F-1  

SciTech Connect

Results from the new Tandem Mirror Experiment (TMX) are described. Tandem-mirror density and potential profiles are produced using end-plug neutral-beam injection and central-cell gas-fueling. TMX parameters are near those predicted theoretically. The end-plug electron temperature is higher than in the comparably sized single-mirror 2XIIB. Axial confinement of the finite-beta central-cell plasma is improved by the end plugs by as much as a factor of 9. In TMX, end-plug microinstability limits central-cell confinement in agreement with theory.

Simonen, T.C.; Anderson, C.A.; Casper, T.A.

1980-05-22

422

VMSMULTI enhancement  

SciTech Connect

VMSMULTI is a general purpose data analysis program which runs under VAX/VMS and is used for the analysis of data previously logged onto magnetic tape. This paper describes the enhancements to the latest version of Fermilab VMSMULTI. The existing analysis features were extended and the new ones - like storing and loading the histograms - were added/ The graphics library was exchanged for the new one which uses DI-3000 graphics from Precision Visuals. Modifications were made to run VMSMULTI in a batch mode, in VMS subprocess or detached process.

Boni, P.

1987-08-01

423

Determination of six anti-infectives in wastewater using tandem solid-phase extraction and liquid chromatography-tandem mass spectrometry.  

PubMed

A rugged and specific method based on tandem solid-phase extraction and liquid chromatography-tandem mass spectrometry for the determination of anti-infectives in raw sewage and wastewater plant effluents was developed. Analyte recoveries from spiked effluents ranged from 68 to 104%. Two specific selected reaction monitoring transitions and their peak area ratios were used to avoid false positives and confirm the presence of the targeted substances. Detection limits allowed low nanogram per litre detection (0.3-22 ng L(-1)). The method was successfully applied to real samples from the Montréal wastewater treatment plant. All the studied anti-infectives were found in the wastewater samples in concentrations ranging from 39 to 276 ng L(-1). Mean flows of anti-infectives were estimated from effluent concentrations and it was found that large amounts (>118 g day(-1) up to 830 g day(-1)) are discharged in the receiving waters of the St Lawrence River. PMID:17410305

Segura, Pedro A; García-Ac, Araceli; Lajeunesse, André; Ghosh, Dipankar; Gagnon, Christian; Sauvé, Sébastien

2007-03-13

424

Tandem repeats discovery service (TReaDS) applied to finding novel cis-acting factors in repeat expansion diseases  

PubMed Central

Background Tandem repeats are multiple duplications of substrings in the DNA that occur contiguously, or at a short distance, and may involve some mutations (such as substitutions, insertions, and deletions). Tandem repeats have been extensively studied also for their association with the class of repeat expansion diseases (mostly affecting the nervous system). Comparative studies on the output of different tools for finding tandem repeats highlighted significant differences among the sets of detected tandem repeats, while many authors pointed up how critical it is the right choice of parameters. Results In this paper we present TReaDS - Tandem Repeats Discovery Service, a tandem repeat meta search engine. TReaDS forwards user requests to several state of the art tools for finding tandem repeats and merges their outcome into a single report, providing a global, synthetic, and comparative view of the results. In particular, TReaDS allows the user to (i) simultaneously run different algorithms on the same data set, (ii) choose for each algorithm a different setting of parameters, and (iii) obtain a report that can be downloaded for further, off-line, investigations. We used TReaDS to investigate sequences associated with repeat expansion diseases. Conclusions By using the tool TReaDS we discover that, for 27 repeat expansion diseases out of a currently known set of 29, long fuzzy tandem repeats are covering the expansion loci. Tests with control sets confirm the specificity of this association. This finding suggests that long fuzzy tandem repeats can be a new class of cis-acting elements involved in the mechanisms leading to the expansion instability. We strongly believe that biologists can be interested in a tool that, not only gives them the possibility of using multiple search algorithm at the same time, with the same effort exerted in using just one of the systems, but also simplifies the burden of comparing and merging the results, thus expanding our capabilities in detecting important phenomena related to tandem repeats.

2012-01-01

425

Enhanced flow-injection–chemiluminometric determination of sulphonamides by on-line photochemical reaction  

Microsoft Academic Search

The viability of the tandem photochemical reaction-chemiluminescence detection has been studied for an heterogeneous group of sulphonamides (sulphamethoxazole, sulphadiazine, sulphamerazine, sulphamethoxypyridazine, sulphacetamide, sulphadimidine, sulphanilamide, sulphathiazole and sulphaguanidine) using sulphamethoxazole (whose chemiluminescent behaviour has not been previously reported) as a test substance. The ‘on-line’ photochemical-reaction of sulphonamides provides an enhancing influence on the chemiluminometric response of the drugs during their oxidation

M. Catalá Icardo; J. V. Garc??a Mateo; M. Fernández Lozano; J. Mart??nez Calatayud

2003-01-01

426

Proteomic analysis of human O {sup 6}-methylguanine-DNA methyltransferase by affinity chromatography and tandem mass spectrometry  

SciTech Connect

Recent evidence suggests that human O {sup 6}-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that protects the genome against mutagens and accords tumor resistance to many anticancer alkylating agents, may have other roles besides repair. Therefore, we isolated MGMT-interacting proteins from extracts of HT29 human colon cancer cells using affinity chromatography on MGMT-Sepharose. Specific proteins bound to this column were identified by electrospray ionization tandem mass spectrometry and/or Western blotting. These procedures identified >60 MGMT-interacting proteins with diverse functions including those involved in DNA replication and repair (MCM2, PCNA, ORC1, DNA polymerase {delta}, MSH-2, and DNA-dependent protein kinase), cell cycle progression (CDK1, cyclin B, CDK2, CDC7, CDC10, 14-3-3 protein, and p21{sup waf1/cip1}), RNA processing and translation (poly(A)-binding protein, nucleolin, heterogeneous nuclear ribonucleoproteins, A2/B1, and elongation factor-1{alpha}), several histones (H4, H3.4, and H2A.1), and topoisomerase I. The heat shock proteins, HSP-90{alpha} and {beta}, also bound strongly with MGMT. The DNA repair activity of MGMT was greatly enhanced in the presence of interacting proteins or histones. These data, for the first time, suggest that human MGMT is likely to have additional functions, possibly, in sensing and integrating the DNA damage/repair-related signals with replication, cell cycle progression, and genomic stability.

Niture, Suryakant K. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Doneanu, Catalin E. [Mass Spectrometry Center, Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195 (United States); Velu, Chinavenmeni S. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Bailey, Nathan I. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Srivenugopal, Kalkunte S. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States)]. E-mail: Kalkunte.srivenugopal@ttuhsc.edu

2005-12-02

427

High Efficiency Narrow Gap and Tandem Junction Devices: Final Technical Report, 1 May 2002--31 October 2004  

SciTech Connect

The work described in this report uses a modified pulsed plasma-enhanced chemical vapor deposition (PECVD) technique that has been successfully developed to fabricate state-of-the-art nc-Si materials and devices. Specifically, we have achieved the following benchmarks: nc SiH device with an efficiency of 8% achieved at a deposition rate of {approx}1 A/s; nc SiH device with an efficiency of 7% achieved at a deposition rate of {approx}5 A/s; large-area technology developed using pulsed PECVD with uniformity of +/-5% over 25 cm x 35 cm; devices have been fabricated in the large-area system (part of Phase 3); an innovative stable four-terminal (4-T) tandem-junction device of h> 9% fabricated. (Note that the 4-T device was fabricated with existing technology base and with further development can reach stabilized h of 12%); and with improvement in Voc {approx} 650 mV, from the current value of 480 mV can lead to stable 4-T device with h>16%. Toward this objective, modified pulsed PECVD was developed where layer- by-layer modification of nc-SiH has been achieved. (Note that due to budget cuts at NREL, this project was curtailed by about one year.)

Madan, A

2005-03-01

428

Molecular basis of antibody mediated immunity against Ehrlichia chaffeensis involves species-specific linear epitopes in tandem repeat proteins  

PubMed Central

Humoral immune mechanisms are an important component of protective immunity to Ehrlichia species. However, the molecular basis of antibody mediated immunity is not completely defined, and the role of other molecularly characterized major immunoreactive proteins is unknown. In previous studies, we mapped major species-specific continuous epitopes in three surface exposed and secreted tandem repeat proteins (TRP32, TRP47 and TRP120). In this study, we report that protection is provided by antibodies against these molecularly defined TRP epitopes using in vitro and in vivo models. Protection was demonstrated in vitro after prophylactic and therapeutic administration of epitope-specific anti-TRP antibodies, suggesting that the protective mechanisms involve extracellular and intracellular antibody-mediated effects. In vivo passive transfer of individual epitope-specific TRP sera significantly reduced the ehrlichial load and splenomegaly, and protected mice against lethal infection. Moreover, the combination of antibodies to all three TRPs provided enhanced reduction in ehrlichial load similar to that of E. chaffeensis immune sera. IgG1 was the predominant antibody isotype in the epitope-specific TRP mouse sera. These results demonstrate that antibodies against linear epitopes in TRP32, TRP47 and TRP120 are protective during E. chaffeensis infection and involves extracellular and intracellular antibody-mediated mechanisms.

Kuriakose, Jeeba A.; Zhang, Xiaofeng; Luo, Tian; McBride, Jere W.

2012-01-01

429

[Rapid screening of 176 pesticide residues in vegetables by ultra fast liquid chromatography-tandem mass spectrometry].  

PubMed

A multiresidue analytical method for rapid screening of 176 pesticide residues in vegetables was developed by using ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS). The vegetable samples were extracted by acetonitrile. It is not necessary for the extract to make a further purification after salting out. Multiple reaction monitoring with information-dependent acquisition of enhanced product ion (MRM-IDA-EPI) was used for the analysis. Based on EPI spectra and chromatographic peak area, identification and quantification of the 176 pesticide residues in vegetables were carried out by using library search technique. All the pesticides had the good linearity within their respective linear ranges (r > 0.99). The average recoveries of the 174 pesticides except for carbosulfan and cyromazine were in the range of 72.4% to 126.4% with the relative standard deviations (RSDs) from 1.0% to 18.7%. The limits of detection and quantification of the method were 0.005 - 2.0 microg/kg and 0.1 - 10 microg/kg, respectively. The results demonstrated that the method has distinct advantages of rapid speed, high sensitivity and good accuracy. Therefore, this method is suitable for the rapid screening of pesticide residues in vegetables. PMID:23667993

Zheng, Shuning; Li, Lingyun; Lin, Huan; Zhao, Wen; Zhang, Yanguo; Yao, Zhoulin; Liu, Su

2013-01-01

430

[Analysis of perfluorinated compounds in sludge by liquid extraction and high performance liquid chromatography-tandem mass spectrometry].  

PubMed

Perfluorinated compounds are emerging persistent organic pollutants. Wastewater treatment plants are reported to be one of their primary sources. However, a standard analytical method for sludge samples has not been set up. A novel and rapid analytical method based on the liquid extraction, followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was set up for 7 perfluorocarboxylic acids (PFCAs) and their precursors, 6:2 and 8:2 unsaturated flourotelomer carboxylic acids (FTUCAs), and 2 perfluoroalkyl sulfonates (PFASs) and their precursors, 5 derivates of sulfonamide in sludge. The parameters of methanol extraction, including pH, sonication temperature and time, and eluent volume were optimized. The extraction method was optimized as neutral extraction under sonication at 40 degrees C for 10 min, and it was successfully used for the analysis of perfluorinated compounds in the sludge samples. The linear calibration curves were obtained in the ranges of 0.1-20 microg/L for PFCAs and 6: 2/8: 2 FTUCA and 0.25-50 microg/L for PFASs and their precusors with linear correlation coefficients larger than 0.99. The recoveries of the target compounds ranged from 74% to 141% (except for FTUCAs) and the limits of quantification ranged from 0.6 to 30 microg/kg (dry weight). The use of internal standards can well correct the ion suppression (or enhancement) induced by co-eluting components present in the sample extracts, and improve the quantitative accuracy. PMID:20812628

Zhang, Tao; Sun, Hongwen; Alder, Alfredo C; Gerecke, Andreas C; Müller, Claudia

2010-05-01

431

Covalently linking the Escherichia coli global anaerobic regulator FNR in tandem allows it to function as an oxygen stable dimer.  

PubMed

The anaerobic global regulator FNR from Escherichia coli is a [4Fe-4S](2+) cluster containing, O(2) labile dimer that plays an important role in adapting the bacterium to its anaerobic lifestyle. Although functional significance of this global regulator has been well established, its structural and biochemical characterizations have been hindered by the intrinsic O(2) lability of FNR protein. To obtain oxygen stable FNR variants for in vitro characterizations, in this study, we utilized the approach of covalently linking two fnr alleles in tandem to promote their in situ dimerization in the absence of the [4Fe-4S](2+) cluster under aerobic conditions. By covalently linking two alleles of fnrD154A mutant, which has reduced charge repulsions between two FNR monomers, an FNR variant of FNRD154A-Linker-FNRD154A (designated as (FNRD154A)(2)) was constructed. (FNRD154A)(2) displayed significantly enhanced DNA binding affinities and transcriptional regulatory activities to various FNR dependent promoters under aerobic conditions. Further in vivo and in vitro studies demonstrated that this variant retains oxygen sensing capability and maintains a similar secondary structure as that formed by native monomers of FNRD154A. We conclude that this novel variant of FNR can be widely used in various biochemical and structural studies of FNR in the presence of O(2). PMID:22326866

Shan, Yue; Pan, Qing; Liu, Junyan; Huang, Feijuang; Sun, Hongzhe; Nishino, Kunihiko; Yan, Aixin

2012-01-31

432

Detection of peginesatide in equine serum using liquid chromatography-tandem mass spectrometry for doping control purposes.  

PubMed

Erythropoietin (EPO) and its recombinant analogues are suspected to be illicitly administered to horses for performance enhancing purposes and, consequently, prohibited in equine sports. Recently, a new erythropoiesis-stimulating agent, peginesatide (Omontys, formerly referred to as Hematide), belonging to the upcoming class of EPO-mimetic peptides, received approval for the treatment of anaemia in humans with chronic kidney disease on dialysis. As the pegylated dimeric peptide of approximately 45 kDa without sequence homology to EPO is not detectable by conventional EPO detection assays, specific methods are bound to be established for horse sports drug testing. Thus, by fortifying equine serum with peginesatide, an approach consisting of a proteolytic digestion with subtilisin after protein precipitation was developed, eventually targeting a proteotypic and xenobiotic pentapeptide which is easily accessible to liquid chromatography- tandem mass spectrometry analysis. The method was validated for qualitative purposes and demonstrated to be specific, precise (relative standard deviations below 14%), sensitive (limit of detection 10 ng mL(-1)) and linear. Being simple, cost-effective and readily transferable to other doping control laboratories, a mass spectrometric assay for the detection of therapeutic concentrations of peginesatide in equine serum is, in terms of preventive doping research, applicable to routine analysis shortly after approval of the drug. PMID:22971699

Möller, Ines; Thomas, Andreas; Wingender, Anke; Machnik, Marc; Schänzer, Wilhelm; Thevis, Mario

2012-01-01

433

Detection of buffalo mozzarella adulteration by an ultra-high performance liquid chromatography tandem mass spectrometry methodology.  

PubMed

Over the past years, LC-MS-based approaches have gained a growing interest in food analysis by using different platforms and methodologies. In particular, enhanced selectivity and sensitivity of multiple reaction monitoring (MRM) scan function offer powerful capabilities in detecting and quantifying specific analytes within complex mixtures such as food matrices. The MRM approach, traditionally applied in biomedical research, is particularly suitable for the detection of food adulteration and for the verification of authenticity to assure food safety and quality, both recognized as top priorities by the European Union Commission. Increasingly stringent legislation ensure products safety along every step 'from farm to fork', especially for traditional foods designed with the Protected Designation of Origin certification. Therefore, there is a growing demand of new methodologies for defining food authenticity in order to preserve their unique traits against frauds. In this work, an ultra performance liquid chromatopgraphy-electrospray ionization-tandem mass spectrometry (MS/MS) methodology based on MRM has been developed for the sensitive and selective detection of buffalo mozzarella adulteration. The targeted quantitative analysis was performed by monitoring specific transitions of the phosphorylated ?-casein f33-48 peptide, identified as a novel species-specific proteotypic marker. The high sensitivity of MRM-based MS and the wide dynamic range of triple quadrupole spectrometers have proved to be a valuable tool for the analysis of food matrices such as dairy products, thus offering new opportunities for monitoring food quality and adulterations. PMID:23147815

Russo, Rosita; Severino, Valeria; Mendez, Alberto; Lliberia, Josep; Parente, Augusto; Chambery, Angela

2012-11-01

434

Quantification of the 5-lipoxygenase inhibitor zileuton in human plasma using high performance liquid chromatography-tandem mass spectrometry.  

PubMed

Zileuton is an orally active, selective inhibitor of 5-lipoxygenase, which catalyzes the first step in the conversion of arachadonic acid into leukotrienes. Given the important role of leukotrienes in inflammation and cell signaling, multiple studies have investigated the efficacy of zileuton in the treatment of human disease. Examples of disease targets include asthma, ulcerative colitis, rheumatoid arthritis, and more recently, acne, ischemic/reperfusion injury, inflammatory pain, and sickle cell anemia. Zileuton is currently approved for the prophylaxis and chronic treatment of asthma. We report the development and validation of a sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the quantification of zileuton in human EDTA plasma. The range of reliable response was 3.05-20,000ng/mL in human plasma. The calibration curves had a correlation coefficient of r(2)>0.99. The intra-day precision was 3.4-5.3%. The inter-day precision ranged from 4.5% to 7.3% and inter-day accuracy from 100% to 107%. No matrix interferences, ion suppression/enhancement, or carry-over was observed. The assay met all predefined acceptance criteria and was subsequently employed to measure plasma zileuton concentrations in a clinical trial. PMID:24029553

Pian, Phillip; Labovitz, Edward; Hoffman, Keith; Clavijo, Claudia F; Rzasa Lynn, Rachael; Galinkin, Jeffrey L; Vinks, Alexander A; Malik, Punam; Christians, Uwe

2013-08-28

435

Application of Power-Factor Correction in the Tandem Mirror Experiment Upgrade Magnet Power Supply.  

National Technical Information Service (NTIS)

The magnet power supply for the Tandem Mirror Experiment Upgrade (TMX Upgrade) contains 24 groups of dc rectifiers that feed the water-cooled magnets. Each group consists of five or less rectifiers, connected in series. All 24 are current-regulating, usin...

W. C. Corvin

1981-01-01

436

Fluorescence generation from tandem repeats of a malachite green RNA aptamer using rolling circle transcription  

Microsoft Academic Search

We demonstrate a generation of tandem repeats of a malachite green (MG) RNA aptamer using rolling circle transcription. To keep the higher-order structure of each aptamer on long RNA, we designed a sequence of circular DNA with a 14-base linker. T7 RNA polymerase was superior to Escherichia coli RNA polymerase in the specific transcription of the MG RNA aptamer. Finally,

Kazuhiro Furukawa; Hiroshi Abe; Naoko Abe; Mitsuru Harada; Satoshi Tsuneda; Yoshihiro Ito

2008-01-01

437

Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing  

Microsoft Academic Search

Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiOx) layer separates and connects the front cell and the back cell.

Jin Young Kim; Kwanghee Lee; Nelson E. Coates; Daniel Moses; Thuc-Quyen Nguyen; Mark Dante; Alan J. Heeger

2007-01-01

438

Iodine-catalyzed tandem synthesis of terminal acetals and glycol mono esters from olefins.  

PubMed

A new metal-free protocol is described for the synthesis of terminal acetals by tandem oxidative rearrangement of olefins using oxone as an oxidant in the presence of iodine. Moreover, a one-pot procedure for the preparation of glycol mono esters from olefins is also presented for the first time using the same reagent system. PMID:23340691

Kumar, Macharla Arun; Swamy, Peraka; Naresh, Mameda; Reddy, Marri Mahender; Rohitha, Chozhiyath Nappunni; Prabhakar, Sripadi; Sarma, Akella Venkata Subrahmanya; Kumar, Joseph Richard Prem; Narender, Nama

2013-02-28

439

Lisinopril quantification in human plasma by liquid chromatography–electrospray tandem mass spectrometry  

Microsoft Academic Search

An analytical method based on liquid chromatography with positive ion electrospray ionization (ESI) coupled to tandem mass spectrometry detection was developed for the determination of Lisinopril in human plasma using Enalaprilat as internal standard. The analyte and internal standard were extracted from the plasma samples by solid-phase extraction using Waters HLB Oasis® SPE cartridges and chromatographed on a C8 analytical

Ana A. F Padua; Rafael E Barrientos-Astigarraga; Vinicius M Rezende; Gustavo D Mendes; Gilberto De Nucci

2004-01-01

440

The penicillin gene cluster is amplified in tandem repeats linked by conserved hexanucleotide sequences.  

PubMed

The penicillin biosynthetic genes (pcbAB, pcbC, penDE) of Penicillium chrysogenum AS-P-78 were located in a 106.5-kb DNA region that is amplified in tandem repeats (five or six copies) linked by conserved TTTACA sequences. The wild-type strains P. chrysogenum NRRL 1951 and Penicillium notatum ATCC 9478 (Fleming's isolate) contain a single copy of the 106.5-kb region. This region was bordered by the same TTTACA hexanucleotide found between tandem repeats in strain AS-P-78. A penicillin overproducer strain, P. chrysogenum E1, contains a large number of copies in tandem of a 57.9-kb DNA fragment, linked by the same hexanucleotide or its reverse complementary TGTAAA sequence. The deletion mutant P. chrysogenum npe10 showed a deletion of 57.9 kb that corresponds exactly to the DNA fragment that is amplified in E1. The conserved hexanucleotide sequence was reconstituted at the deletion site. The amplification has occurred within a single chromosome (chromosome I). The tandem reiteration and deletion appear to arise by mutation-induced site-specific recombination at the conserved hexanucleotide sequences. PMID:7597101

Fierro, F; Barredo, J L; Díez, B; Gutierrez, S; Fernández, F J; Martín, J F

1995-06-20

441

Hydrogen Degree of Dissociation in a Low Pressure Tandem Plasma Source  

Microsoft Academic Search

Hydrogen dissociation degree in an inductively-driven tandem plasma source, operating at low pressure, is measured by applying optical actinometry method with an argon gas as actinometer. The gas temperature, a parameter in the investigations, is obtained from the rotational temperature, analyzing the intensity distribution of the Fulcher-? band. Several actinometric pairs are used for examining the dissociation degree and its

S. Iordanova; I. Koleva; T. Paunska

2011-01-01

442

Tandem and segmental gene duplication and recombination in the evolution of plant disease resistance genes  

Microsoft Academic Search

NBS-LRR genes are the major class of disease resistance genes in flowering plants, and are arranged as single genes and as clustered loci. The evolution of these genes has been investigated in Arabidopsis thaliana by combining data on their genomic organisation and position in phylogenetic trees. Tandem and segmental duplications distribute and separate NBS-LRR genes in the genome. It is,

Dario Leister

2004-01-01

443

Sample-Path Large Deviations for Tandem and Priority Queues with Gaussian Inputs.  

National Technical Information Service (NTIS)

This paper considers Gaussian flows multiplexed in a queueing network. A single node being a useful but often incomplete setting, we examine more advanced models. We focus on a (two-node) tandem queue, fed by a large number of Gaussian inputs. With servic...

M. J. G. Van Uitert M. R. H. Mandjes

2004-01-01

444

Design of a Stable Tandem Mirror with Thermal Barriers and A-Cells (MFTF-B).  

National Technical Information Service (NTIS)

A self-consistent design is described for a large tandem mirror experiment (MFTF-B) proposed to be constructed at the Lawrence Livermore Laboratory. Neutral-beam injected yin-yang mirror cells at each end of a 40 meter long central cell, provide MHD stabi...

B. G. Logan

1980-01-01

445

Making the Case for Objective Performance Metrics in Newborn Screening by Tandem Mass Spectrometry  

ERIC Educational Resources Information Center

The expansion of newborn screening programs to include multiplex testing by tandem mass spectrometry requires understanding and close monitoring of performance metrics. This is not done consistently because of lack of defined targets, and interlaboratory comparison is almost nonexistent. Between July 2004 and April 2006 (N = 176,185 cases), the…

Rinaldo, Piero; Zafari, Saba; Tortorelli, Silvia; Matern, Dietrich

2006-01-01

446

Visible and V.U.V. emission measurements in a tandem multicusp ion source  

Microsoft Academic Search

Relative measurements of vacuum ultraviolet and visible emission from a tandem multipole H? ion source are presented. In particular the change in emission intensity with plasma parameters and viewing region has been studied. The production rate of H2 (v?5) has been estimated. (AIP)

W. G. Graham; M. B. Hopkins

1987-01-01

447

Numerical analysis of plasma transport in tandem volume magnetic multicusp ion sources  

Microsoft Academic Search

A one-dimensional fluid model of plasma transport in tandem volume magnetic multicusp ion sources is explored. The model, a positive ion source code, calculates plasma density, drift velocity, electron temperature, and ion temperature in an ion source. The usefulness of the model is limited in the following ways: (1) the plasma density trend runs opposite to experimental results, and electron

Todd R. Vitko

1992-01-01

448

Visible and V.U.V. emission measurements in a tandem multicusp ion source  

Microsoft Academic Search

Relative measurements of vacuum ultraviolet and visible emission from a tandem multipole H- ion source are presented. In particular the change in emission intensity with plasma parameters and viewing region has been studied. The production rate of H2 (v>=5) has been estimated. (AIP)

W. G. Graham; M. B. Hopkins

1987-01-01

449

Plasma parameter characterization of a tandem multicusp ion source operating in H2 and D2  

Microsoft Academic Search

The basic plasma parameters of a tandem multicusp ion source operating with hydrogen and deuterium gas have been measured and are compared. It is found that there is little variation in the electron temperature or electron energy-distribution function; however, both the electron density and plasma potential are consistently higher when operating with D2 rather than