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1

Tandem shock waves to enhance genetic transformation of Aspergillus niger.  

PubMed

Filamentous fungi are used in several industries and in academia to produce antibiotics, metabolites, proteins and pharmaceutical compounds. The development of valuable strains usually requires the insertion of recombinant deoxyribonucleic acid; however, the protocols to transfer DNA to fungal cells are highly inefficient. Recently, underwater shock waves were successfully used to genetically transform filamentous fungi. The purpose of this research was to demonstrate that the efficiency of transformation can be improved significantly by enhancing acoustic cavitation using tandem (dual-pulse) shock waves. Results revealed that tandem pressure pulses, generated at a delay of 300?s, increased the transformation efficiency of Aspergillus niger up to 84% in comparison with conventional (single-pulse) shock waves. This methodology may also be useful to obtain new strains required in basic research and biotechnology. PMID:24680880

Loske, Achim M; Fernández, Francisco; Magaña-Ortíz, Denis; Coconi-Linares, Nancy; Ortíz-Vázquez, Elizabeth; Gómez-Lim, Miguel A

2014-08-01

2

I kappaB alpha-independent downregulation of NF-kappaB activity by glucocorticoid receptor.  

PubMed Central

I kappaB alpha is an inhibitor protein that prevents nuclear transport-and activation of the transcription factor NF-kappaB. In acute inflammation, NF-kappaB is activated and increases the expression of several pro-inflammatory cytokine and chemokine genes. Glucocorticoids counteract this process. It has been proposed that the glucocorticoid-dependent inhibition of NF-kappaB activity is mediated by increased synthesis of I kappaB alpha which should then sequester NF-kappaB in an inactive cytoplasmic form. Here, we show by the use of a mutant glucocorticoid receptor and steroidal ligands that hormone-induced I kappaB alpha synthesis and inhibition of NF-kappaB activity are separable biochemical processes. A dimerization-defective glucocorticoid receptor mutant that does not enhance the I kappaB alpha level is still able to repress NF-kappaB activity. Conversely, glucocorticoid analogues competent in enhancing I kappaB alpha synthesis do not repress NF-kappaB activity. These results demonstrate that increased synthesis of I kappaB alpha is neither required nor sufficient for the hormone-mediated downmodulation of NF-kappaB activity.

Heck, S; Bender, K; Kullmann, M; Gottlicher, M; Herrlich, P; Cato, A C

1997-01-01

3

Efficiency enhancement utilizing hybrid charge generation layer in tandem organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

We report the incorporation of lithium fluoride doped 4,7-diphenyl-1,10-phenanthroline, Al, and molybdenum trioxide which is utilized to form the charge generation layer in tandem organic light-emitting diodes. Both the fluorescent and phosphorescent tandem devices based on this hybrid charge generation layer show the enhanced luminous efficiency and reduced operating voltage compared with the devices using conventional charge generation layer. The mechanism of the efficiency enhancement is ascribed to the improvement of charge balance due to the efficient charge separation in the hybrid charge generation layer. The hybrid layer can act as the effective charge injection buffer layer as well.

Xiao, J.; Wang, X. X.; Zhu, H.; Gao, X.; Yang, Z. H.; Zhang, X. H.; Wang, S. D.

2012-07-01

4

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

5

Enhanced light absorption in thin-film tandem solar cells using a bottom metallic nanograting  

NASA Astrophysics Data System (ADS)

We introduced a metallic nanograting at the bottom of thin-film tandem solar cells, and carried out an investigation into the light absorption in the top and bottom cells via the electromagnetic simulation. It indicates that broadband and polarization-insensitive light absorption enhancement can be obtained in the bottom cell, while the light absorption in the top cell remains unchanged by the influence of the added metallic nanograting. An overall carrier generation enhancement reaches as much as 60 % for both incident polarizations. This absorption enhancement can survive in a wide range of the cell thickness and the nanograting geometries, which enables us to reduce the thickness of the bottom cell with minimal impact on the light absorption. Thereby, this design could reduce the solar cell production cost, and meanwhile could enhance the solar cell efficiency by decreasing the light-generated carrier recombination rate.

Zhang, Xuanru; Knize, Randy J.; Lu, Yalin

2014-05-01

6

Evolution of the tandem repeats in thymidylate synthase enhancer region (TSER) in primates.  

PubMed

The upstream regulatory region of the human thymidylate synthase gene (thymidylate synthase enhancer region, TSER) is length polymorphic, attributable to variable numbers of tandemly repeated copies of a 28-bp fragment. It has been found that TSER length polymorphism is correlated to malignancy risk. To further our understanding of the origin and evolution of TSER, this region was investigated among different primates, including hominoids, two subfamilies of the Old World monkeys (OWMs): colobines and cercopithecines, and two species of the New World monkeys (NWMs). In addition to humans, our results show that length polymorphism in TSER is also present in some primate populations, although it appears that this region is length monomorphic in many other primates. We identified three unique repeat motifs in TSER and defined them as R1, R2, and R3, respectively, starting from the 3' end. The same repeat motifs from different species are more similar to each other than different repeat motifs within same species are. Such a paraphyletic pattern suggests that divergence of the three repeat motifs predated divergence of the OWMs/hominoids and the NWMs. The most recent common ancestor (MRCA) of hominoids and the OWMs probably possessed triple repeats but now double and triple repeats are two dominant types in hominoids and the OWMs. In addition, our results show that each of the three repeat motifs may be lost independently. We have also found clues that recombination was involved in formation of tandem repeat polymorphism in TSER. PMID:15302405

Zhang, Yun-Wu; Luo, Huai-Rong; Ryder, Oliver A; Zhang, Ya-Ping

2004-08-18

7

Expression of the tandem enhanced yellow fluorescent marker gene in Toxoplasma gondii.  

PubMed

Fluorescent protein is a useful tool for monitoring gene expression and studying biological processes of organisms including parasites. To improve the transfection efficiency and fluorescent intensity in Toxoplasma gondii, a new transient expression vector, RGES, containing the tandem enhanced yellow fluorescent protein gene, EYFP-EYFP, under the control of the parasite dense granule protein 1 (GRA1) promoter was constructed. The RGES plasmid was introduced into T. gondii RH strain by electroporation. A high proportion of tachyzoites (approximately 25.5%) was transfected with the EYFP-EYFP gene and high fluorescence intensity was detected 48-72 h after electroporation. The tandem EYFP gene and its expression in the transfectants were confirmed by polymerase chain reaction (PCR), reverse transcriptase PCR, and Western blotting. The efficiency of transfection and fluorescent intensity of EYFP-EYFP were greater than that of the single EYFP or green fluorescent protein. The EYFP-EYFP gene is a better marker for the study of biological processes of T. gondii. PMID:19424723

Li, Xuelian; Hao, Yongxin; Chen, Dan; Liu, Qun; Ding, Jun; Zhang, Wei

2009-07-01

8

Surface-up constructed tandem-inverted bilayer cyclodextrins for enhanced enantioseparation and adsorption.  

PubMed

A new generation of triazole-bridged bilayer cyclodextrins (CDs) chiral stationary phase (CSP) material was constructed via a surface-up 'click' approach. The synergistic effect of the tandem-inverted duplex CDs was evidenced by the superior enantioresolution ability toward selected chiral compounds and the enhanced adsorption ability toward hesperetin. The enantioselectivities of dansyl amino acids and aryl carboxylic acids were promoted by 10-20%, while the resolutions of some aryl carboxylic acids were significantly increased from 0 to 3.5 and beyond. Adsorption experiments of hesperetin reveal that the binding ability of the target bilayer CDCSP is nearly 2.8 times than that of the single layer CDCSP. The current work provides a simple and practical approach to design and synthesize novel functional materials with cooperative CD dimers on surfaces. PMID:24720902

Zhao, Jie; Lu, Xiaohong; Wang, Yong; Tan, Timothy Thatt Yang

2014-05-23

9

Performance enhancement of existing two-stage sounding rocket vehicles through the use of tandem booster systems  

NASA Technical Reports Server (NTRS)

The three-stage Taurus-Nike-Tomahawk launch vehicle is being considered for performance enhancement of the existing Taurus-Tomahawk flight system. In addition, performance enhancement of other existing two-stage launch vehicles is being considered through the use of tandem booster systems. Aeroballistic characteristics of the proposed Taurus-Nike-Tomahawk vehicle are presented, as are overall performance capabilities of other potential three-stage flight systems.

Flores, C. C.; Gurkin, L. W.

1982-01-01

10

Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode.  

PubMed

Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n(+)-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm(-2), respectively, are achieved under 1 sun illumination. The 4 mA cm(-2) photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode. PMID:23893238

Abdi, Fatwa F; Han, Lihao; Smets, Arno H M; Zeman, Miro; Dam, Bernard; van de Krol, Roel

2013-01-01

11

Correction of errors in tandem mass spectrum extraction enhances phosphopeptide identification.  

PubMed

The tandem mass spectrum extraction of phosphopeptides is more difficult and error-prone than that of unmodified peptides due to their lower abundance, lower ionization efficiency, the cofragmentation with other high-abundance peptides, and the use of MS(3) on MS(2) fragments with neutral losses. However, there are still no established methods to evaluate its correctness. Here we propose to identify and correct these errors via the combinatorial use of multiple spectrum extraction tools. We evaluated five free and two commercial extraction tools using Mascot and phosphoproteomics raw data from LTQ FT Ultra, in which RawXtract 1.9.9.2 identified the highest number of unique phosphopeptides (peptide expectation value <0.05). Surprisingly, ProteoWizzard (v. 3.0.3476) extracted wrong precursor mass for most MS(3) spectra. Comparison of the top three free extraction tools showed that only 54% of the identified spectra were identified consistently from all three tools, indicating that some errors might happen during spectrum extraction. Manual check of 258 spectra not identified from all three tools revealed 405 errors of spectrum extraction with 7.4% in selecting wrong precursor charge, 50.6% in selecting wrong precursor mass, and 42.1% in exporting MS/MS fragments. We then corrected the errors by selecting the best extracted MGF file for each spectrum among the three tools for another database search. With the errors corrected, it results in the 22.4 and 12.2% increase in spectrum matches and unique peptide identification, respectively, compared with the best single method. Correction of errors in spectrum extraction improves both the sensitivity and confidence of phosphopeptide identification. Data analysis on nonphosphopeptide spectra indicates that this strategy applies to unmodified peptides as well. The identification of errors in spectrum extraction will promote the improvement of spectrum extraction tools in future. PMID:24147958

Hao, Piliang; Ren, Yan; Tam, James P; Sze, Siu Kwan

2013-12-01

12

Intracellular Thiols Regulate Activation of Nuclear Factor kappaB and Transcription of Human Immunodeficiency Virus  

Microsoft Academic Search

The activation of nuclear factor kappaB (NF-kappaB) has been implicated in the regulation of transcription of a variety of genes and has been shown to be essential for the expression of genes controlled by the long terminal repeat of human immunodeficiency virus (HIV LTR). We show here that intracellular thiol levels play a key role in regulating this process. That

Frank J. T. Staal; Mario Roederer; Leonard A. Herzenberg; Leonore A. Herzenberg

1990-01-01

13

Pulsed Multiple Reaction Monitoring Approach to Enhancing Sensitivity of a Tandem Quadrupole Mass Spectrometer  

SciTech Connect

Liquid chromatography (LC)-triple quadrupole mass spectrometers operating in a Multiple Reaction Monitoring (MRM) mode are increasingly used for quantitative analysis of low abundance analytes in highly complex biochemical matrices. After development and selection of optimum MRM transition, sensitivity and data quality limitations are largely related to mass spectral peak interferences from sample or matrix constituents and statistical limitations at low number of ions reaching the detector. Herein, we report a new approach to enhancing MRM sensitivity by converting the continuous stream of ions from the ion source into a pulsed ion beam through the use of an Ion Funnel Trap (IFT). Evaluation of the pulsed MRM approach was performed with a tryptic digest of Shewanella oneidensis strain MR-1 spiked with several reference peptides. The sensitivity improvement observed with the IFT coupled to the triple quadrupole instrument is based on several unique features. First, ion accumulation in the radio frequency (RF) ion trap facilitates improved droplet desolvation, which is manifested in the reduced background ion noise at the detector. Second, signal amplitude for a given transition is enhanced because of an order-of-magnitude increase in the ion charge density per unit time compared to a continuous mode of operation. Third, signal detection at the full duty cycle is obtained, as the trap use eliminates dead times between transitions, which are inevitable with continuous ion streams. In comparison with the conventional approach, the pulsed MRM signals showed up to 5-fold enhanced peak amplitude and 2-3 fold reduced chemical background, resulting in an improvement in the limit of detection (LOD) by a factor of ~ 4 to ~ 8.

Belov, Mikhail E.; Prasad, Satendra; Prior, David C.; Danielson, William F.; Weitz, Karl K.; Ibrahim, Yehia M.; Smith, Richard D.

2011-02-23

14

Pulsed Multiple Reaction Monitoring Approach to Enhancing Sensitivity of a Tandem Quadrupole Mass Spectrometer  

PubMed Central

Liquid chromatography (LC)–triple quadrupole mass spectrometers operating in a multiple reaction monitoring (MRM) mode are increasingly used for quantitative analysis of low-abundance analytes in highly complex biochemical matrixes. After development and selection of optimum MRM transitions, sensitivity and data quality limitations are largely related to mass spectral peak interferences from sample or matrix constituents and statistical limitations at low number of ions reaching the detector. Herein, we report on a new approach to enhancing MRM sensitivity by converting the continuous stream of ions from the ion source into a pulsed ion beam through the use of an ion funnel trap (IFT). Evaluation of the pulsed MRM approach was performed with a tryptic digest of Shewanella oneidensis strain MR-1 spiked with several model peptides. The sensitivity improvement observed with the IFT coupled in to the triple quadrupole instrument is based on several unique features. First, ion accumulation radio frequency (rf) ion trap facilitates improved droplet desolvation, which is manifested in the reduced background ion noise at the detector. Second, signal amplitude for a given transition is enhanced because of an order-of-magnitude increase in the ion charge density compared to a continuous mode of operation. Third, signal detection at the full duty cycle is obtained, as the trap use eliminates dead times between transitions, which are inevitable with continuous ion streams. In comparison with the conventional approach, the pulsed MRM signals showed 5-fold enhanced peak amplitude and 2–3-fold reduced chemical background, resulting in an improvement in the limit of detection (LOD) by a factor of ~4–8.

Belov, Mikhail E.; Prasad, Satendra; Prior, David C.; Danielson, William F.; Weitz, Karl; Ibrahim, Yehia M.; Smith, Richard D.

2011-01-01

15

Enhancing the response of alkyl methylphosphonic acids in negative electrospray ionization liquid chromatography tandem mass spectrometry by post-column addition of organic solvents  

Microsoft Academic Search

A method to enhance the signal intensity and signal-to-noise of several alkyl methylphosphonic acids in negative electrospray\\u000a ionization liquid chromatography tandem mass spectrometry (ESI LC-MS\\/MS) is presented. This class of compound represents the\\u000a initial metabolites and environmental degradants of the nerve agents: VX, rVX (Russian VX), GB (Sarin), GF (Cyclosarin), and\\u000a GD (Soman). Compared with the post-column addition of the

Douglas B. Mawhinney; Rayman D. Stanelle; Elizabeth I. Hamelin; Robert J. Kobelski

2007-01-01

16

Energy Transfer Mechanisms in Polymer Systems. II. Design and Demonstration of an Enhancement of the Efficiency of a Solid Phase Chemiluminescent System Based upon Spin Forbidden Steps and a Tandem Energy Transfer.  

National Technical Information Service (NTIS)

The efficiency of indirect chemiluminescence of anthracene, chemiexcited by thermolysis of tetramethyl-1,2-dioxetane in polystyrene, is much greater in a polymer medium than in fluid motion. The basis of this enhanced efficiency is the tandem combination ...

N. J. Turro H. C. Steinmetzer

1974-01-01

17

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

18

Tandem repeats of lactoferrin-derived anti-hepatitis C virus peptide enhance antiviral activity in cultured human hepatocytes.  

PubMed

Previously, we found that bovine and human lactoferrin (LF) specifically inhibited hepatitis C virus (HCV) infection in cultured non-neoplastic human hepatocyte-derived PH5CH8 cells, and we identified 33 amino acid residues (termed C-s3-33; amino acid 600-632) from human LF that were primarily responsible for the binding activity to the HCV E2 envelope protein and for the inhibiting activity against HCV infection. Since the anti-HCV activity of C-s3-33 was weaker than that of human LF, we speculated that an increase of E2 protein-binding activity might contribute to the enhancement of anti-HCV activity. To test this possibility, we made two repeats [(C-s3-33)(2)] and three repeats [(C-s3-33)(3)] of C-s3-33 and characterized them. Far-Western blot analysis revealed that the E2 protein-binding activities of (C-s3-33)(2) and (C-s3-33)(3) became stronger than that of the C-s3-33, and that the binding activity of (C-s3-33)(3) was stronger than that of (C-s3-33)(2). Using an HCV infection system in PH5CH8 cells, we demonstrated that the anti-HCV activities of (C-s3-33)(2) and (C-s3-33)(3) became stronger than that of the C-s3-33. Furthermore, using a recently developed infection system with a VSV pseudotype harboring the green fluorescent protein gene and the native E1 and E2 genes, we demonstrated that the antiviral activities of (C-s3-33)(2) and (C-s3-33)(3) were stronger than that of C-s3-33. These results suggest that tandem repeats of LF-derived anti-HCV peptide are useful as anti-HCV reagents. PMID:17237607

Abe, Ken-ichi; Nozaki, Akito; Tamura, Kazushi; Ikeda, Masanori; Naka, Kazuhito; Dansako, Hiromichi; Hoshino, Hiro-O; Tanaka, Katsuaki; Kato, Nobuyuki

2007-01-01

19

Replication mutations differentially enhance RecA-dependent and RecA-independent recombination between tandem repeats in Bacillus subtilis.  

PubMed

We have studied DNA recombination between 513 bp tandem direct repeats present in a kanamycin resistance gene inserted in the Bacillus subtilis chromosome. Tandem repeat deletion was not significantly affected by a recA mutation. However, recombination was stimulated by mutations in genes encoding replication proteins, including the primosomal proteins DnaB, DnaD and the DnaG primase, the putative DNA polymerase III subunits PolC, DnaN and DnaX, as well as the DNA polymerase DnaE. Hyper-recombination was found to be dependent on RecA in the dnaE, dnaN and dnaX mutants, whereas the dnaG and dnaD mutants stimulated recombination independently of RecA. Altogether, these data show that both RecA-dependent and RecA-independent mechanisms contribute to recombination between tandem repeats in B. subtilis and that both types of recombination are stimulated by replication mutations. PMID:11251841

Bruand, C; Bidnenko, V; Ehrlich, S D

2001-03-01

20

Glancing angle deposited ITO films for efficiency enhancement of a-Si:H/?c-Si:H tandem thin film solar cells.  

PubMed

Indium tin oxide (ITO) thin films with relatively high transparency and low absorption are prepared by glancing angle deposition (GLAD) method and their effect on the device performance of a-Si:H/?c-Si:H tandem thin film solar cells is theoretically investigated by applying the experimentally measured physical data of the fabricated films to the simulation parameters. The GLAD of ITO produces inclined porous columnar nanostructures due to the atomic shadowing effect. With increasing the incident flux angle, the columns are increasingly inclined, thus resulting in the improved transmission property as well as the decrease of the refractive index and extinction coefficient because of enhanced porosity within the film. Furthermore, the antireflection characteristics are improved over a wide wavelength range of 300-1100 nm. For a-Si:H/?c-Si:H tandem thin film solar cell structure incorporated with the 0° ITO/80° ITO bi-layer structure, the conversion efficiency (?) of 13.6% is obtained from simulation under AM1.5g illumination, indicating an efficiency improvement compared to the device with the 0° ITO/0° ITO bi-layer structure (i.e. ? = 12.58%). PMID:21643367

Leem, Jung Woo; Yu, Jae Su

2011-05-01

21

Differential activation of heat shock and nuclear factor kappaB transcription factors in postischemic reperfused rat liver  

Microsoft Academic Search

The aim of this study was to investigate the behavior of the transcription factors, heat-shock factor (HSF) and nuclear factor kappaB (NF-kappaB), in postischemic reperfused liver, with particular attention paid to possible differences in the time-course and mechanism of activation, which may help in defining their role in the response of the liver to reperfusion. Ischemia was induced by clamping

L Tacchini; L Radice; G Pogliaghi; A Bernelli-Zazzera

1997-01-01

22

Systemic targeting inhibitor of kappaB kinase inhibits melanoma tumor growth.  

PubMed

Constitutive activation of nuclear factor-kappaB (NF-kappaB) has been directly implicated in tumorigenesis of various cancer types, including melanoma. Inhibitor of kappaB kinase (IKK) functions as a major mediator of NF-kappaB activation. Thus, development of an IKK-specific inhibitor has been a high priority, although it remains unclear whether systemic inhibition of IKK will provide therapeutic benefit. In this study, we show that inhibition of NF-kappaB activity in melanocytes that are persistently expressing an active H-Ras(V12) gene and are deficient in the tumor suppressors inhibitor A of cyclin-dependent kinase 4/alternative reading frame results in reduction of melanoma tumor growth in vivo. This effect is, at least in part, via regulation of NF-kappaB nuclear activation and RelA phosphorylation. Based on this result, we developed a double hammerhead ribozyme long-term expression system to silence either IKKalpha or IKKbeta. The ribozymes were placed in an EBV construct and delivered i.v. to nude mice bearing melanoma lesions, which developed after i.v. injection of H-Ras-transformed melanoma cells. Our in vivo data show that knockdown of endogenous IKKbeta significantly reduces the growth of the melanoma lesions and knockdown of either IKKalpha or IKKbeta prolongs the life span of immunocompetent mice. PMID:17409419

Yang, Jinming; Pan, Wei-Hua; Clawson, Gary A; Richmond, Ann

2007-04-01

23

NF kappaB expression increases and CFTR and MUC1 expression decreases in the endometrium of infertile patients with hydrosalpinx: a comparative study  

PubMed Central

Background Hydrosalpinx are associated with infertility, due to reduced rates of implantation and increased abortion rates. The aims of this study were to investigate the expression of cystic fibrosis transmembrane conductance regulator (CFTR), nuclear factor kappa B (NF KappaB) and mucin-1 (MUC-1), and analyze the correlation between the expression of CFTR and NF KappaB or MUC1, in the endometrium of infertile women with and without hydrosalpinx. Methods Thirty-one infertile women with laparoscopy-confirmed unilateral or bilateral hydrosalpinx and 20 infertile women without hydrosalpinx or pelvic inflammatory disease (control group) were recruited. Endometrial biopsy samples were collected and the expression of CFTR, NF KappaB and MUC1 were analyzed using immunohistochemistry and quantitative real-time PCR. Results CFTR, NF KappaB and MUC1 mRNA and protein expression tended to increase in the secretory phase compared to the proliferative phase in both groups; however, these differences were not significantly different. The endometrium of infertile patients with hydrosalpinx had significantly higher NF KappaB mRNA and protein expression, and significantly lower CFTR and MUC1 mRNA and protein expression, compared to control infertile patients. A positive correlation was observed between CFTR and MUC1 mRNA expression (r = 0.65, P < 0.05); a negative correlation was observed between CFTR mRNA and NF KappaB mRNA expression (r = ?0.59, P < 0.05). Conclusions Increased NF KappaB expression and decreased CFTR and MUC1 expression in the endometrium of infertile patients with hydrosalpinx reinforce the involvement of a molecular mechanism in the regulation of endometrial receptivity.

2012-01-01

24

Simultaneous detection of variable number tandem repeats, single nucleotide polymorphisms, and allelic imbalance in the thymidylate synthase gene enhancer region using denaturing high-performance liquid chromatography.  

PubMed

Polymorphisms in the thymidylate synthase enhancer region (TSER) have been reported to be associated with alterations in thymidylate synthase (TS) mRNA protein levels. The TSER is characterized by the presence of variable double (2R) and triple (3R) number tandem repeats (VNTRs). In addition to VNTRs, single nucleotide polymorphisms (SNPs) and allelic imbalance (AI), including loss of heterozygosity (LOH), have recently been associated with response to 5-fluorouracil (5-FU)-based chemotherapy. The aim of the current study was to develop a specific denaturing high-performance liquid chromatography (DHPLC) method for the rapid detection of these variations in the TSER in clinical samples. DHPLC analysis was validated in parallel with agarose gel electrophoresis (AGE), enzyme digestion, and quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR). The optimized DHPLC method resolved 100% of the known TSER variations, differentiated between homozygous and heterozygous genotypes, and allowed the qualitative and quantitative detection of AI, including LOH, in tumor samples. This DHPLC method was developed to permit the rapid, sensitive, and accurate identification of the TSER genotype (VNTRs, SNPs, and AI) in clinical protocols where response to flouropyrimidines may be correlated with TSER polymorphisms. PMID:15494134

Ezzeldin, Hany; Hoffmayer, Cornelia; Soong, Richie; Johnson, Martin R; Lee, Adam; Heslin, Marty; Diasio, Robert

2004-11-15

25

Cytotoxic enhancement of a bispecific diabody by format conversion to tandem single-chain variable fragment (taFv): the case of the hEx3 diabody.  

PubMed

Diabodies (Dbs) and tandem single-chain variable fragments (taFv) are the most widely used recombinant formats for constructing small bispecific antibodies. However, only a few studies have compared these formats, and none have discussed their binding kinetics and cross-linking ability. We previously reported the usefulness for cancer immunotherapy of a humanized bispecific Db (hEx3-Db) and its single-chain format (hEx3-scDb) that target epidermal growth factor receptor and CD3. Here, we converted hEx3-Db into a taFv format to investigate how format affects the function of a small bispecific antibody; our investigation included a cytotoxicity assay, surface plasmon resonance spectroscopy, thermodynamic analysis, and flow cytometry. The prepared taFv (hEx3-taFv) showed an enhanced cytotoxicity, which may be attributable to a structural superiority to the diabody format in cross-linking target cells but not to differences in the binding affinities of the formats. Comparable cross-linking ability for soluble antigens was observed among hEx3-Db, hEx3-scDb, and hEx3-taFv with surface plasmon resonance spectroscopy. Furthermore, drastic increases in cytotoxicity were found in the dimeric form of hEx3-taFv, especially when the two hEx3-taFv were covalently linked. Our results show that converting the format of small bispecific antibodies can improve their function. In particular, for small bispecific antibodies that target tumor and immune cells, a functional orientation that avoids steric hindrance in cross-linking two target cells may be important in enhancing the growth inhibition effect. PMID:21097496

Asano, Ryutaro; Ikoma, Keiko; Shimomura, Ippei; Taki, Shintaro; Nakanishi, Takeshi; Umetsu, Mitsuo; Kumagai, Izumi

2011-01-21

26

Inhibition of nuclear factor kappa-B signaling reduces growth in medulloblastoma in vivo  

PubMed Central

Background Medulloblastoma is a highly malignant pediatric brain tumor that requires surgery, whole brain and spine irradiation, and intense chemotherapy for treatment. A more sophisticated understanding of the pathophysiology of medulloblastoma is needed to successfully reduce the intensity of treatment and improve outcomes. Nuclear factor kappa-B (NF?B) is a signaling pathway that controls transcriptional activation of genes important for tight regulation of many cellular processes and is aberrantly expressed in many types of cancer. Methods To test the importance of NF?B to medulloblastoma cell growth, the effects of multiple drugs that inhibit NF?B, pyrrolidine dithiocarbamate, diethyldithiocarbamate, sulfasalazine, curcumin and bortezomib, were studied in medulloblastoma cell lines compared to a malignant glioma cell line and normal neurons. Expression of endogenous NF?B was investigated in cultured cells, xenograft flank tumors, and primary human tumor samples. A dominant negative construct for the endogenous inhibitor of NF?B, I?B, was prepared from medulloblastoma cell lines and flank tumors were established to allow specific pathway inhibition. Results We report high constitutive activity of the canonical NF?B pathway, as seen by Western analysis of the NF?B subunit p65, in medulloblastoma tumors compared to normal brain. The p65 subunit of NF?B is extremely highly expressed in xenograft tumors from human medulloblastoma cell lines; though, conversely, the same cells in culture have minimal expression without specific stimulation. We demonstrate that pharmacological inhibition of NF?B in cell lines halts proliferation and leads to apoptosis. We show by immunohistochemical stain that phosphorylated p65 is found in the majority of primary tumor cells examined. Finally, expression of a dominant negative form of the endogenous inhibitor of NF?B, dnI?B, resulted in poor xenograft tumor growth, with average tumor volumes 40% smaller than controls. Conclusions These data collectively demonstrate that NF?B signaling is important for medulloblastoma tumor growth, and that inhibition can reduce tumor size and viability in vivo. We discuss the implications of NF?B signaling on the approach to managing patients with medulloblastoma in order to improve clinical outcomes.

2011-01-01

27

Caffeic acid phenethyl ester inhibits osteoclastogenesis by suppressing NF kappaB and downregulating NFATc1 and c-Fos.  

PubMed

Osteoclasts are multinuclear cells of myeloid lineage responsible for bone resorption. The anti-inflammatory property of caffeic acid phenethyl ester (CAPE), an active component of the propolis of honeybee hives, has been revealed. Since the regulatory mechanism of differentiation and activation of osteoclasts shares many well-known signaling pathways with that of inflammation, we investigated whether CAPE has any effect on osteoclastogenesis. CAPE potently suppressed osteoclastogenesis in cultures of bone marrow-derived precursor cells with the osteoclast differentiation factor, receptor activator of nuclear factor kappaB ligand (RANKL). While the RANKL-stimulated activation of the ERK, JNK, and p38 MAPK signaling pathways was not affected, the DNA binding and transcription activity of NF kappaB were reduced by CAPE treatment. In addition, CAPE blocked the induction of NFATc1 and c-Fos following RANKL stimulation. Forced expression of c-Fos could reverse the inhibitory effect of CAPE on osteoclastogenesis. Finally, CAPE significantly inhibited the RANKL-induced osteoclast formation in mouse calvariae in vivo. We propose that CAPE might be useful as a therapeutic agent for treatment of bone destructive diseases. PMID:19285574

Ha, Jeongim; Choi, Hyo-Sun; Lee, Youngkyun; Lee, Zang Hee; Kim, Hong-Hee

2009-06-01

28

Inhibition of nuclear factor kappaB activation by a virus-encoded IkappaB-like protein.  

PubMed

Certain viruses have evolved mechanisms to counteract innate immunity, a host response in which nuclear factor kappaB (NF-kappaB) transcription factors play a central role. African swine fever virus encodes a protein of 28.2 kDa containing ankyrin repeats similar to those of cellular IkappaB proteins, which are inhibitors of NF-kappaB. Transfection of the African swine fever virus IkappaB gene inhibited tumor necrosis factor- or phorbol ester-induced activation of kappaB- but not AP-1-driven reporter genes. Moreover, African swine fever virus IkappaB co-immunoprecipitated with p65 NF-kappaB, and the purified recombinant protein prevented the binding of p65-p50 NF-kappaB proteins to their target sequences in the DNA. NF-kappaB activation induced by tumor necrosis factor, as detected by mobility shift assays or by transfection of kappaB-driven reporter genes, is impaired in African swine fever virus-infected cells. These results indicate that the African swine fever virus IkappaB gene homologue interferes with NF-kappaB activation, likely representing a new mechanism to evade the immune response during viral infection. PMID:9479002

Revilla, Y; Callejo, M; Rodríguez, J M; Culebras, E; Nogal, M L; Salas, M L; Viñuela, E; Fresno, M

1998-02-27

29

An enhanced throughput method for quantification of sulfur mustard adducts to human serum albumin via isotope dilution tandem mass spectrometry.  

PubMed

Here, we report an enhanced throughput method for the diagnosis of human exposure to sulfur mustard. A hydroxyethylthioethyl (HETE) ester-adducted tripeptide, produced by pronase digestion of human serum albumin, was selected as the quantitative exposure biomarker. Cibacron Blue enrichment was developed from an established cartridge method into a 96-well plate format, increasing throughput and ruggedness. This new method decreased sample volume 2.5-fold. Addition of a precipitation and solid-phase extraction concentration step increased the sensitivity of the method. With the conversion to a 96-well plate and optimization of chromatography, the method resulted in a 3-fold decrease in analysis time. Inclusion of a confirmation ion has increased specificity. The method was found to be linear between 0.050 and 50 µM sulfur mustard exposure with a precision for both quality control samples of ?6.5% relative standard deviation and an accuracy of >96%. The limit of detection (3So) was calculated to be ?0.0048 µM, an exposure value similar to that of the HETE-albumin adduct method first described by Noort and co-workers (Noort et al., 1999; Noort el al., 2004) which used protein precipitation to isolate albumin. A convenience set of 124 plasma samples from healthy unexposed individuals was analyzed using this method to assess background levels of exposure to sulfur mustard; no positive results were detected. PMID:24201816

Andacht, Tracy M; Pantazides, Brooke G; Crow, Brian S; Fidder, Alex; Noort, Daan; Thomas, Jerry D; Blake, Thomas A; Johnson, Rudolph C

2014-01-01

30

Receptor activator of nuclear factor kappaB (RANK) is expressed as a late event during malignant progression in Barrett's metaplasia  

Microsoft Academic Search

Receptor activator of NF-kappaB (RANK) activation induces several survival signals including nuclear factor kappaB (NF-kappaB) and activation and upregulation of Bcl-xL. The aim of this work was to determine whether RANK is expressed in oesophageal adenocarcinoma (EA) and its precursor, Barrett's metaplasia (BM). Sections of formalin-fixed and paraffin-embedded tissue from 23 oesophagectomy specimens showing EA and variable degrees of dysplasia

R. Yorke; A. Younes; M. Chirala; M. Younes

2003-01-01

31

Asbestos Induces Nuclear Factor kappaB (NF-kappaB) DNA-Binding Activity and NF-kappaB-Dependent Gene Expression in Tracheal Epithelial Cells  

Microsoft Academic Search

Nuclear factor kappaB (NF-kappaB) is a transcription factor regulating expression of genes intrinsic to inflammation and cell proliferation-features of asbestos-associated diseases. In studies here, crocidolite asbestos caused protracted and dose-responsive increases in proteins binding to nuclear NF-kappaB-binding DNA elements in hamster tracheal epithelial (HTE) cells. This binding was modulated by cellular glutathione levels. Antibodies recognizing p65 and p50 protein members

Yvonne M. W. Janssen; Aaron Barchowsky; Melinda Treadwell; Kevin E. Driscoll; Brooke T. Mossman

1995-01-01

32

Enhanced Expression of Interleukin8 and Activation of Nuclear Factor Kappa-B in Endoscopy-negative Gastroesophageal Reflux Disease  

Microsoft Academic Search

OBJECTIVE:Interleukin-8 (IL-8) mediates neutrophil trafficking via its receptors. Recent studies have shown that IL-8 is likely involved in the development and progression of erosive reflux esophagitis (RE), yet little is known about its implication in endoscopy-negative gastroesophageal reflux disease (GERD). The purpose of this study was to determine IL-8 messenger ribonucleic acid (mRNA) expression levels in endoscopy-negative GERD, along with

Hajime Isomoto; Vladimir A. Saenko; Yusei Kanazawa; Yoshito Nishi; Akira Ohtsuru; Kenichiro Inoue; Yuko Akazawa; Fuminao Takeshima; Katsuhisa Omagari; Masanobu Miyazaki; Yohei Mizuta; Ikuo Murata; Shunichi Yamashita; Shigeru Kohno

2004-01-01

33

Phytoestrogen bavachin mediates anti-inflammation targeting Ikappa B kinase-I kappaB alpha-NF-kappaB signaling pathway in chondrocytes in vitro.  

PubMed

The pro-inflammatory cytokine interleukin-1 beta (IL-1 beta) plays critical roles in pathogenesis of osteoarthritis. Although estrogen is protective for cartilage in osteoarthritis patients, it also potentially increases the risk of stroke and cancer. Phytoestrogens acting as natural estrogen receptor modulators may serve as alternatives. This study aimed to identify medicinal phytoestrogens that preserve anti-inflammatory property and may function as potential chondro-protective compounds. Both human chondrocytes and chondrocytic cell line CHON-002 were used for this study. Protein concentrations or expressions were measured by ELISA or Western blot, respectively. The DNA-binding activity and transcriptional activity of transcription factors were evaluated by electrophoretic mobility shift assay and dual-luciferase reporter assay, respectively. Cell migration was analyzed by chemotaxis assays. We found that among screened phytoestrogens, bavachin could potently decrease IL-1 beta-induced nuclear factor-kappa B (NF-kappaB) but not activator protein-1 (AP-1) DNA-binding activity. Bavachin also inhibited I kappaB alpha degradation, increased nuclear translocation of p65 and p50 as well as decreased I kappaB alpha kinase (IKK) activity. Furthermore, bavachin inhibited IL-1 beta-induced chemokine production that resulted in reduced migration of THP-1 monocytic cells. Our results suggest that through decreasing IL-1 beta-induced activation of IKK-I kappaB alpha-NF-kappaB signaling pathway, bavachin potentially protects cartilage from inflammation-mediated damage in joints of osteoarthritis patients. PMID:20361957

Cheng, Cheng-Chung; Chen, Yi-Hsin; Chang, Wen-Liang; Yang, Shih-Ping; Chang, Deh-Ming; Lai, Jenn-Haung; Ho, Ling-Jun

2010-06-25

34

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

2011-07-01

35

Activation of peroxisome proliferator-activated receptor-gamma protects pancreatic beta-cells from cytokine-induced cytotoxicity via NF kappaB pathway.  

PubMed

Diabetes mellitus is characterized by cytokine-induced insulitis and a deficit in beta-cell mass. Ligands for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) have been shown to have anti-inflammatory effects in various experimental models. We questioned whether activation of endogenous PPAR-gamma by either PPAR-gamma ligands or adenoviral-directed overexpression of PPAR-gamma (Ad-PPAR-gamma) could inhibit cytokine-induced beta-cell death in RINm5F (RIN) cells, a rat insulinoma cell line. Treatment of RIN cells with interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) induced beta-cell damage through NF kappaB-dependent signaling pathways. Activation of PPAR-gamma by PPAR-gamma ligands or Ad-PPAR-gamma inhibited IL-1 beta and IFN-gamma-stimulated nuclear translocation of the p65 subunit and DNA binding activity. NF kappaB target gene expression and their product formation, namely inducible nitric oxide synthase and cyclooxygenase-2 were decreased by PPAR-gamma activation, as established by real-time PCR, Western blots and measurements of NO and PGE(2). The mechanism by which PPAR-gamma activation inhibited NF kappaB-dependent cell death signals appeared to involve the inhibition of I kappa B alpha degradation, evidenced by inhibition of cytokine-induced NF kappaB-dependent signaling events by Ad-I kappaB alpha (S32A, S36A), non-degradable I kappaB alpha mutant. I kappaB beta mutant, Ad-I kappaB beta (S19A, S23A) was not effective in preventing cytokine toxicity. Furthermore, a protective effect of PPAR-gamma ligands was proved by assaying for normal insulin secreting capacity in response to glucose in isolated rat pancreatic islets. The beta-cell protective function of PPAR-gamma ligands might serve to counteract cytokine-induced beta-cell destruction. PMID:17521952

Kim, Eun-Kyung; Kwon, Kang-Beom; Koo, Bon-Sun; Han, Mi-Jeong; Song, Mi-Young; Song, Eun-Kyung; Han, Myung-Kwan; Park, Jin-Woo; Ryu, Do-Gon; Park, Byung-Hyun

2007-01-01

36

Thermal-barrier production and indentification in a tandem mirror  

SciTech Connect

In thermal-barrier experiments in the tandem mirror experiment upgrade axial confinement times of 50 to 100 ms have been achieved. During enhanced confinement we measured the thermal-barrier potential profile using a neutral-particle-beam probe. The experimental data agree qualitatively and quantitatively with the theory of thermal-barrier formation in a tandem mirror.

Grubb, D.P.; Allen, S.L.; Casper, T.A.; Clauser, J.F.; Coensgen, F.H.; Correll, D.L.; Cummins, W.F.; Damm, C.C.; Foote, J.H.; Goodman, R.K.; Hill, D.N.; Hooper,Jr., E.B.; Hornady, R.S.; Hunt, A.L.; Kerr, R.G.; Leppelmeier, G.W.; Marilleau, J.; Moller, J.M.; Molvik, A.W.; Nexsen, W.E.; Pickles, W.L.; Porter, G.D.; Poulsen, P.; Silver, E.H.; Simonen, T.C.; Stallard, B.W.; Turner, W.C.; Hsu, W.L.; Yu, T.L.; Barter, J.D.; Christensen, T.; Dimonte, G.; Romesser, T.W.; Ellis, R.F.; James, R.A.; Lasnier, C.J.; Berzins, L.V.; Carter, M.R.; Clower, C.A.; Failor, B.H.; Falabella, S.; Flammer, M.; Nash, T.

1984-08-20

37

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

38

Induction of nuclear factor kappaB by the CD30 receptor is mediated by TRAF1 and TRAF2.  

PubMed Central

CD30 is a lymphoid cell-specific surface receptor which was originally identified as an antigen expressed on Hodgkin's lymphoma cells. Activation of CD30 induces the nuclear factor kappaB (NF-kappaB) transcription factor. In this study, we define the domains in CD30 which are required for NF-kappaB activation. Two separate elements of the cytoplasmic domain which were capable of inducing NF-kappaB independently of one another were identified. The first domain (domain 1) mapped to a approximately 120-amino-acid sequence in the membrane-proximal region of the CD30 cytoplasmic tail, between residues 410 and 531. A second, more carboxy-terminal region (domain 2) was identified between residues 553 and 595. Domain 2 contains two 5- to 10-amino-acid elements which can mediate the binding of CD30 to members of the tumor necrosis factor receptor-associated factor (TRAF) family of signal transducing proteins. Coexpression of CD30 with TRAF1 or TRAF2 but not TRAF3 augmented NF-kappaB activation through domain 2 but not domain 1. NF-kappaB induction through domain 2 was inhibited by coexpression of either full-length TRAF3 or dominant negative forms of TRAF1 or TRAF2. In contrast, NF-kappaB induction by domain 1 was not affected by alterations in TRAF protein levels. Together, these data support a model in which CD30 can induce NF-kappaB by both TRAF-dependent and -independent mechanisms. TRAF-dependent induction of NF-kappaB appears to be regulated by the relative levels of individual TRAF proteins in the cell.

Duckett, C S; Gedrich, R W; Gilfillan, M C; Thompson, C B

1997-01-01

39

Tandem pairing in heavy-fermion superconductors.  

PubMed

We consider the internal structure of a d-wave heavy-fermion superconducting condensate, showing that it necessarily contains two components condensed in tandem: pairs of quasiparticles on neighboring sites and composite pairs consisting of two electrons bound to a single local moment. These two components draw upon the antiferromagnetic and Kondo interactions to cooperatively enhance the superconducting transition temperature. This tandem condensate is electrostatically active, with an electric quadrupole moment predicted to lead to a superconducting shift in the nuclear quadrupole resonance frequency. PMID:21231540

Flint, Rebecca; Coleman, Piers

2010-12-10

40

Tandem mobile robot system  

DOEpatents

A robotic vehicle system for terrain navigation mobility provides a way to climb stairs, cross crevices, and navigate across difficult terrain by coupling two or more mobile robots with a coupling device and controlling the robots cooperatively in tandem.

Buttz, James H. (Albuquerque, NM); Shirey, David L. (Albuquerque, NM); Hayward, David R. (Albuquerque, NM)

2003-01-01

41

Quantification of serum C-peptide by isotope-dilution liquid chromatography-tandem mass spectrometry: enhanced detection using chemical modification and immunoaffinity purification.  

PubMed

A method was developed to quantify human serum C-peptide by isotope-dilution mass spectrometry (ID MS). This new approach used immunoaffinity purification and chemical modification to improve the sensitivity which covered the wide range of reference interval of serum C-peptide. The immunoaffinity purification was performed using monoclonal antibody against human C-peptide that was immobilized on magnetic beads, and the purified C-peptide was chemically modified using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS). With this method, the LC-MS/MS peak area increased 23-fold compared with the conventional purification by solid-phase extraction and without chemical modification. The limit of quantification was estimated to be 0.003ng on column, which was lower than previously reported. The validation study showed that (1) the response in the 0.003-2.9ng range on column was linear (regression coefficient, r(2)=0.9994), (2) the relative standard deviation (RSD) within and between days was inferior to 4.0%, and (3) the spike and recovery test showed the mean recoveries ranging between 99% and 108%. Comparison with an established commercial immunoassay showed high correlation (r(2)=0.9994) at serum concentration of 0.19-8.49ng/mL. These assessments suggest that this ID MS-based approach can quantify human serum C-peptide with high sensitivity and precision in the reference interval and find a potential use in the reference measurement procedure of serum C-peptide, allowing traceable measurement. This method may also generally be applied to peptide quantification in biological fluids with high sensitivity. PMID:24607695

Kinumi, Tomoya; Mizuno, Ryoko; Takatsu, Akiko

2014-03-15

42

A simple parallel tandem organic solar cell based on metallophthalocyanines  

NASA Astrophysics Data System (ADS)

A simple parallel tandem solar cell based on a combination of Zn-phthalocyanine (Pc) and ClInPc has been fabricated and characterized. Compared to a traditional series tandem cell, parallel tandem cells eliminate the need for a semitransparent recombination layer, reducing the complexity of device fabrication while still providing an excellent increase in device performance. Results show a realized broadening of the spectral response and enhancement of the external quantum efficiency as a result of the complementary absorption profiles of ZnPc and ClInPc in the near infrared region. Introduction of a blended ClInPc:C60 layer is shown to more than double the power conversion efficiency of a standard ZnPc/C60 bilayer device (PCE=0.86%). The enhanced performance of the parallel tandem (PCE=1.81%) arises from an increase in both the open circuit voltage and the short circuit current.

Yuen, Avery P.; Hor, Ah-Mee; Preston, John S.; Klenkler, Richard; Bamsey, Nathan M.; Loutfy, Rafik O.

2011-04-01

43

Simultaneous qualitative and quantitative method using liquid chromatography selected reaction monitoring-triggered quantitation-enhanced data-dependent tandem mass spectrometry for the identification and classification of amphetamine-type stimulant abusers in human urine.  

PubMed

Amphetamine (AP) and amphetamine-type stimulants, methamphetamine (MA) and N,N-dimethylamphetamine (DMA), are known as central nervous system stimulants, and their abuse throughout the world has recently increased. Since it is difficult to physically distinguish among AP, MA and DMA, analysts may not be aware of what abusers have administered. In this study, following the detection of specific metabolites of AP, MA and DMA as biomarkers in abuser urines, a rapid and sensitive method was developed for the identification and classification of AP-type stimulants abusers. After the simple filtration of the urine samples, the samples were directly analyzed using a liquid chromatography/tandem mass spectrometry system with selected reaction monitoring (SRM)-triggered quantitation-enhanced data-dependent MS/MS (QED-MS/MS) for the simultaneous qualitative and quantitative analysis of p-hydroxy AP, p-hydroxy MA, p-hydroxy DMA, AP, MA, DMA and DMA N-oxide. The determination of p-hydroxy AP, p-hydroxy MA, AP, MA, DMA and DMA N-oxide was accurate and reproducible, with the limits of quantitation of 5?ng/mL in urine. When applied to the urine samples of suspected AP-type stimulants abusers, the abused drugs were precisely identified between MA and DMA abusers. PMID:20941760

Lee, Sang Kyu; Kim, So-Hee; Kim, Ho Jun; Yoo, Hye Hyun; Kwon, Oh Seung; In, Moon Kyo; Jin, Changbae; Kim, Dong Hyun; Lee, Jaeick

2010-11-15

44

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

45

Tandem resonator reflectance modulator  

DOEpatents

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.

Fritz, Ian J. (Albuquerque, NM); Wendt, Joel R. (Albuquerque, NM)

1994-01-01

46

Tandem resonator reflectance modulator  

DOEpatents

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

47

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

48

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

49

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

50

Enhanced nicotine metabolism in HIV-1-positive smokers compared with HIV-negative smokers: simultaneous determination of nicotine and its four metabolites in their plasma using a simple and sensitive electrospray ionization liquid chromatography-tandem mass spectrometry technique.  

PubMed

Smoking is approximately three times more prevalent in HIV-1-positive than HIV-negative individuals in the United States. Nicotine, which is the major constituent of tobacco, is rapidly metabolized mainly by cytochrome P450 (CYP2A6) to many metabolites. In this study, we developed a simple, fast, and sensitive electrospray ionization liquid chromatography-tandem mass spectrometry method using a strong cation solid phase extraction, and determined the concentration of nicotine and its four major metabolites (cotinine, nornicotine, norcotinine, and trans-3'-hydroxycotinine) in the plasma of HIV-1-positive and HIV-negative smokers. The multiple reaction monitoring transitions for nicotine, cotinine, trans-3'-hydroxycotinine, nornicotine, norcotinine, nicotine-d4, and cotinine-d3 were selected at mass-to-charge ratios of 163.3/117.1, 177.5/80.3, 193.2/80.1, 149.5/132.3, 163.4/80.3, 167.3/121.4, and 180.3/101.2, respectively. The lower limit of quantitation for nicotine and its metabolites was 0.53 ng/ml, which is relatively more sensitive than those previously reported. The concentration of nicotine was detected 5-fold lower in HIV-1-positive smokers (7.17 ± 3.8 ng/ml) than that observed in HIV-negative smokers (33.29 ± 15.4 ng/ml), whereas the concentration of the metabolite nornicotine was 3-fold higher in HIV-1-positive smokers (6.8 ± 2.9 ng/ml) than in HIV-negative smokers (2.3 ± 1.2 ng/ml). Although it was statistically nonsignificant, the concentration of the metabolite cotinine was also higher in HIV-1-positive smokers (85.6 ± 60.5 ng/ml) than in HIV-negative smokers (74.9 ± 40.5 ng/ml). In conclusion, a decrease in the concentration of nicotine and an increase in the concentration of its metabolites in HIV-1-positive smokers compared with HIV-negative smokers support the hypothesis that nicotine metabolism is enhanced in HIV-1-positive smokers compared with HIV-negative smokers. PMID:24301609

Earla, Ravinder; Ande, Anusha; McArthur, Carole; Kumar, Anil; Kumar, Santosh

2014-02-01

51

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

52

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

53

Vitamin E as an Antiosteoporotic Agent via Receptor Activator of Nuclear Factor Kappa-B Ligand Signaling Disruption: Current Evidence and Other Potential Research Areas  

PubMed Central

Osteoporosis is a growing healthcare burden that affects the quality of life in the aging population. Vitamin E is a potential prophylactic agent that can impede the progression of osteoporosis. Various in vivo studies demonstrated the antiosteoporotic potential of vitamin E, but evidence on its molecular mechanism of action is limited. A few in vitro studies showed that various forms of vitamin E can affect the receptor activator of nuclear factor kappa-B ligand (RANKL) signaling and their molecular targets, thus preventing the formation of osteoclasts in the early stage of osteoclastogenesis. Various studies have also shown that the effects of the different isoforms of vitamin E differ. The effects of single isoforms and combinations of isoforms on bone metabolism are also different. Vitamin E may affect bone metabolism by disruption of free radical-mediated RANKL signaling, by its oestrogen-like effects, by its effects on the molecular mechanism of bone formation, by the anti-inflammatory effects of its long-chain metabolites on bone cells, and by the inhibition of 3-hydroxyl-3-methyglutaryl coenzyme A (HMG-CoA). In conclusion, the vitamin E isoforms have enormous potential to be used as prophylactic and therapeutic agents in preventing osteoporosis, but further studies should be conducted to elucidate their mechanisms of action.

Chin, Kok-Yong; Ima-Nirwana, Soelaiman

2012-01-01

54

Ten tandem repeats of {beta}-hCG 109-118 enhance immunogenicity and anti-tumor effects of {beta}-hCG C-terminal peptide carried by mycobacterial heat-shock protein HSP65  

SciTech Connect

The {beta}-subunit of human chorionic gonadotropin ({beta}-hCG) is secreted by many kinds of tumors and it has been used as an ideal target antigen to develop vaccines against tumors. In view of the low immunogenicity of this self-peptide,we designed a method based on isocaudamer technique to repeat tandemly the 10-residue sequence X of {beta}-hCG (109-118), then 10 tandemly repeated copies of the 10-residue sequence combined with {beta}-hCG C-terminal 37 peptides were fused to mycobacterial heat-shock protein 65 to construct a fusion protein HSP65-X10-{beta}hCGCTP37 as an immunogen. In this study, we examined the effect of the tandem repeats of this 10-residue sequence in eliciting an immune by comparing the immunogenicity and anti-tumor effects of the two immunogens, HSP65-X10-{beta}hCGCTP37 and HSP65-{beta}hCGCTP37 (without the 10 tandem repeats). Immunization of mice with the fusion protein HSP65-X10-{beta}hCGCTP37 elicited much higher levels of specific anti-{beta}-hCG antibodies and more effectively inhibited the growth of Lewis lung carcinoma (LLC) in vivo than with HSP65-{beta}hCGCTP37, which should suggest that HSP65-X10-{beta}hCGCTP37 may be an effective protein vaccine for the treatment of {beta}-hCG-dependent tumors and multiple tandem repeats of a certain epitope are an efficient method to overcome the low immunogenicity of self-peptide antigens.

Zhang Yankai [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Yan Rong [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); He Yi [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Liu Wentao [Nanjing Medical University, Nanjing 210029 (China); Cao Rongyue [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Yan Ming [National Drug Screening Laboratory, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Li Taiming [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Liu Jingjing [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China); Wu Jie [Minigene Pharmacy Laboratory, Biopharmaceutical College, China Pharmaceutical University, Tongjia Xiang 24, Nanjing 210009 (China)]. E-mail: wu_jie97@yahoo.com.cn

2006-07-14

55

Progress in amorphous silicon tandem modules at Energy Photovoltaics, Inc  

Microsoft Academic Search

Over the past two years, EPV has directed its manufacturing research efforts toward enhancing the productivity of its tandem amorphous silicon (a-Si) photovoltaic module process. One major area of focus has been on streamlining the process to reduce the amount of time and complexity to manufacture a module by eliminating or combining process steps. In addition, significant effort has been

K. W. Jansen; H. Volltrauer; A. Varvar; D. Jackson; B. Johnson; L. Chen; J. A. Znna Selvan; Y.-M. Li; A. E. Delahoy

2005-01-01

56

Fueling of tandem mirror reactors  

SciTech Connect

This paper summarizes the fueling requirements for experimental and demonstration tandem mirror reactors (TMRs), reviews the status of conventional pellet injectors, and identifies some candidate accelerators that may be needed for fueling tandem mirror reactors. Characteristics and limitations of three types of accelerators are described; neutral beam injectors, electromagnetic rail guns, and laser beam drivers. Based on these characteristics and limitations, a computer module was developed for the Tandem Mirror Reactor Systems Code (TMRSC) to select the pellet injector/accelerator combination which most nearly satisfies the fueling requirements for a given machine design.

Gorker, G.E.; Logan, B.G.

1985-01-01

57

Homocysteine stimulates nuclear factor kappaB activity and monocyte chemoattractant protein-1 expression in vascular smooth-muscle cells: a possible role for protein kinase C.  

PubMed Central

Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that stimulates the migration of monocytes into the intima of arterial walls. Although many factors that induce MCP-1 expression have been identified, the effect of homocysteine on the expression of MCP-1 in atherogenesis and the underlying mechanisms are not entirely clear. The objective of the present study was to investigate the role of homocysteine in MCP-1 expression in human aorta vascular smooth-muscle cells (VSMCs). After VSMCs were incubated with homocysteine for various time periods, a nuclease protection assay and ELISA were performed. Homocysteine (0.05-0.2 mM) significantly increased the expression of MCP-1 mRNA (up to 2. 7-fold) and protein (up to 3.3-fold) in these cells. The increase in MCP-1 expression was associated with the activation of protein kinase C (PKC) as well as nuclear factor kappaB (NF-kappaB). Further investigation demonstrated that the activation of NF-kappaB was the result of a PKC-mediated reduction in the expression of inhibitory protein (IkappaBalpha) mRNA and protein in homocysteine-treated cells. Oxidative stress might also be involved in the activation of NF-kappaB by homocysteine in VSMCs. In conclusion, the present study has clearly demonstrated that the activation of PKC as well as superoxide production followed by activation of NF-kappaB is responsible for homocysteine-induced MCP-1 expression in VSMCs. These results suggest that homocysteine-stimulated MCP-1 expression via NF-kappaB activation may play an important role in atherogenesis.

Wang, G; Siow, Y L; O, K

2000-01-01

58

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

2010-03-30

59

Thymoquinone blocks lung injury and fibrosis by attenuating bleomycin-induced oxidative stress and activation of nuclear factor Kappa-B in rats.  

PubMed

Pulmonary fibrosis is one of the most common chronic interstitial lung diseases with high mortality rate after diagnosis and limited successful treatment. The present study was designed to assess the potential antifibrotic effect of thymoquinone (TQ) and whether TQ can attenuate the severity of oxidative stress and inflammatory response during bleomycin-induced pulmonary fibrosis. Male Wister rats were treated intraperitoneally with either bleomycin (15 mg/kg, 3 times a week for 4 weeks) and/or thymoquinone (5mg/kg/day, 1 week before and until the end of the experiment). Bleomycin significantly increased lung weight and the levels of Lactate dehydrogenase, total leucocytic count, total protein and mucin in bronchoalveolar lavage and these effects were significantly ameliorated by TQ treatment. As markers of oxidative stress, bleomycin caused a significant increase in the levels of lipid peroxides and nitric oxide accompanied with a significant decrease in the antioxidant enzyme activity of superoxide dismutase and glutathione transferase. TQ treatment restored these markers toward normal values. TQ also counteracted emphysema in air alveoli, inflammatory cell infiltration, lymphoid hyperplastic cells activation surrounding the bronchioles and the over expression of activated form of nuclear factor kappa-B (NF-B) in lung tissue that was induced by bleomycin. Fibrosis was assessed by measuring hydroxyproline content, which increased markedly in the bleomycin group and significantly reduced by concurrent treatment with TQ. Furthermore, histopathological examination confirmed the antifibrotic effect of TQ. Collectively these findings indicate that TQ has potential antifibrotic effect beside its antioxidant activity that could be through NF-?B inhibition. PMID:22982510

El-Khouly, Dalia; El-Bakly, Wesam M; Awad, Azza S; El-Mesallamy, Hala O; El-Demerdash, Ebtehal

2012-12-16

60

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

61

Pharmacological benefit of I1-imidazoline receptors activation and nuclear factor kappa-B (NF-?B) modulation in experimental Huntington's disease.  

PubMed

Huntington's disease (HD), a neurodegenerative disorder, is characterized by progressive motor dysfunction, emotional disturbances, dementia, weight loss and anxiety. The tremendous amount of research work is required to identify new pharmacological agents of therapeutic utility to combat this condition. This study investigates the effect of selective modulator of I1-imidazoline receptor (moxonidine) as well as nuclear factor kappa-B (NF-?B) (natrium diethyl dithio carbamate trihydrate-NDDCT) on 3-nitropropionic acid (3-NPA) induced experimental HD condition. 3-NPA was used to induce mitochondrial damage and associated HD symptoms in rats. Anxiety was assessed using Elevated plus maze-EPM and learning-memory was assessed using EPM and Morris water maze-MWM. Different biochemical estimations were used to assess brain striatum oxidative stress (lipid peroxide, superoxide dismutase and catalase), nitric oxide levels (nitrite/nitrate), cholinergic activity (brain striatum acetyl cholinesterase activity), and mitochondrial enzyme complex (I, II and IV) activities. 3-NPA has induced anxiety, impaired learning-memory with a reduction in body weight, locomotor activity, grip strength. It has increased brain striatum acetylcholinesterase-AChE activity, oxidative stress (lipid peroxide, nitrite/nitrate, superoxide dismutase and catalase) and impaired mitochondrial complex enzyme (I, II and IV) activities. Tetrabenazine-TBZ (monoamine storage inhibitor) was used as positive control. Treatment with moxonidine, NDDCT and TBZ significantly attenuated 3-NPA induced reduction in body weight, locomotor activity, grip strength, anxiety as well as impaired learning and memory. Administration of these agents attenuated 3-NPA induced various biochemical impairments. Therefore, modulation of I1-imidazoline receptor as well as NF-?B may be considered as potential pharmacological agents for the management of 3-NPA induced HD. PMID:24582883

Gupta, Surbhi; Sharma, Bhupesh

2014-03-01

62

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

63

Inhibition of nuclear factor kappaB activity by viral interferon regulatory factor 3 of Kaposi's sarcoma-associated herpesvirus.  

PubMed

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays an important role in the immune system and cell death. Many viral proteins modulate NF-kappaB to escape host immune surveillance, promote cell survival, and enhance viral replication. In the present study, we show that NF-kappaB activity is downmodulated by viral interferon regulatory factor 3 (vIRF3), which is encoded by Kaposi's sarcoma-associated herpesvirus open-reading frame K10.5. vIRF3 repressed NF-kappaB-dependent transcription in a dose-dependent manner and inhibited the activation of NF-kappaB induced by tumor necrosis factor (TNF)-alpha. In vivo studies showed vIRF3 inhibited IkappaB kinase beta (IKKbeta) activity, but not IKKalpha activity, resulting in reduced IkappaB phosphorylation. Immunofluorescence assays showed that vIRF3 interfered with nuclear translocation of NF-kappaB. In addition, consistent with the inhibition of NF-kappaB activity, vIRF3 sensitized cells to TNF-alpha-induced apoptosis. While vIRF3 interacts with IKKbeta in vitro and in 293T cells, we were unable to demonstrate vIRF3-IKKbeta interaction in BCBL-1 cells. Our results indicate that vIRF3 can regulate the host immune system and apoptosis via inhibition of NF-kappaB activity. PMID:15208654

Seo, Taegun; Park, Junsoo; Lim, Chunghun; Choe, Joonho

2004-08-12

64

Immolina, a High-Molecular-Weight Polysaccharide Fraction of Spirulina, Enhances Chemokine Expression in Human Monocytic THP1 Cells  

Microsoft Academic Search

Introduction: Spirulina (Spirulina platensis) is a dietary supplement valued for its immune-enhancing prop- erties. We previously reported that the immunostimulatory effect of spirulina can be traced to a high-molecu- lar-weight polysaccharide fraction. This fraction, labeled Immolina, activates nuclear factor kappa-B in human monocytic THP-1 cells and increases expression of proinflammatory cytokines. Objective: To characterize further the immunostimulatory effects of Immolina

Reinhard Grzanna; Anna Polotsky; Phong V. Phan; Nirmal Pugh; David Pasco; Carmelita G. Frondoza

2006-01-01

65

Landsat radiometric cross-calibration: extended analysis of tandem image data sets  

NASA Astrophysics Data System (ADS)

The paper presents the results of an extended analysis of image data sets acquired during the tandem-orbit configuration in 1999 for the purposes of radiometric cross-calibration of the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-5 Thematic Mapper (TM) sensors. Earlier work focused on the tandem pair for the Railroad Valley Playa, Nevada (RVPN) site to tie down the Landsat-5 TM calibration based on the more accurate Landsat-7 ETM+ calibration. This paper describes new results based on as many as eight tandem image pairs. The additional tandem images are of vegetated areas for which little or no ground reference data were available. Increasing the number of tandem pairs yielded results for the Landsat 5 TM gain coefficients within approximately +/- 1 % of the RVPN-based results in spectral bands 1, 2, 3 and 7, and within -2 % and -4 % of the RVPN-based results for spectral bands 4 and 5, respectively.

Teillet, P. M.; Markham, Brian L.; Irish, Richard R.

2005-10-01

66

Reduction of tumor necrosis factor-alpha (TNF-?) related nuclear factor-kappaB (NF-?B) translocation but not inhibitor kappa-B (I?-B)-degradation by Rho protein inhibition in human endothelial cells  

Microsoft Academic Search

Degradation of inhibitor kappa-B (I?-B) followed by translocation of nuclear factor-kappaB (NF-?B) into the nucleus and activation of gene expression is essential in tumor necrosis factor-alpha (TNF-?)-signaling. In order to analyze the role of Rho proteins in TNF-?-induced NF-?B-activation in human umbilical cord vein endothelial cells (HUVEC) we used Clostridium difficile toxin B-10463 (TcdB-10463) which inactivates RhoA\\/Rac1\\/Cdc42 by glucosylation and

Stefan Hippenstiel; Bernd Schmeck; Joachim Seybold; Matthias Krüll; Christoph v Eichel-Streiber; Norbert Suttorp

2002-01-01

67

'Fairy Chimney'-shaped tandem metamaterials as double resonance SERS substrates.  

PubMed

A highly tunable design for obtaining double resonance substrates to be used in surface-enhanced Raman spectroscopy is proposed. Tandem truncated nanocones composed of Au-SiO(2)-Au layers are designed, simulated and fabricated to obtain resonances at laser excitation and Stokes frequencies. Surface-enhanced Raman scattering experiments are conducted to compare the enhancements obtained from double resonance substrates to those obtained from single resonance gold truncated nanocones. The best enhancement factor obtained using the new design is 3.86 × 10(7). The resultant tandem structures are named after "Fairy Chimneys" rock formation in Cappadocia, Turkey. PMID:23060087

Cinel, Neval A; Bütün, Serkan; Erta?, Gülay; Ozbay, Ekmel

2013-02-25

68

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

69

Tumour necrosis factor alpha activates nuclear factor kappaB signalling to reduce N-type voltage-gated Ca2+ current in postganglionic sympathetic neurons.  

PubMed

Inflammation has profound effects on the innervation of affected tissues, including altered neuronal excitability and neurotransmitter release. As Ca(2+) influx through voltage-gated Ca(2+) channels (VGCCs) is a critical determinant of excitation-secretion coupling in nerve terminals, the aim of this study was to characterize the effect of overnight incubation in the inflammatory mediator tumour necrosis factor alpha (TNFalpha; 1 nM) on VGCCs in dissociated neurons from mouse superior mesenteric ganglia (SMG). Voltage-gated Ca(2+) currents (I(Ca)) were measured using the perforated patch clamp technique and the VGCC subtypes present in SMG neurons were estimated based on inhibition by selective VGCC blockers: omega-conotoxin GVIA (300 nM; N-type), nifedipine (10 microM; L-type), and omega-conotoxin MVIIC (300 nM; N-, P/Q-type). We used intracellular Ca(2+) imaging with Fura-2 AM to compare Ca(2+) influx during depolarizations in control and TNFalpha-treated neurons. TNF receptor and VGCC mRNA expression were measured using PCR, and channel alpha subunit (CaV2.2) was localized with immunohistochemistry. Incubation in TNFalpha significantly decreased I(Ca) amplitude and depolarization-induced Ca(2+) influx. The reduction in I(Ca) was limited to omega-conotoxin GVIA-sensitive N-type Ca(2+) channels. Depletion of glial cells by incubation in cytosine arabinoside (5 microM) did not affect I(Ca) inhibition by TNFalpha. Preincubation of neurons with SC-514 (20 microM) or BAY 11-7082 (1 microM), which both inhibit nuclear factor kappaB signalling, prevented the reduction in I(Ca) by TNFalpha. Inhibition of N-type VGCCs following TNFalpha incubation was associated with a decrease in CaV2.2 mRNA and reduced membrane localization of CaV2.2 immunoreactivity. These data suggest that TNFalpha inhibits I(Ca) in SMG neurons and identify a novel role for NF-kappaB in the regulation of neurotransmitter release during inflammatory conditions with elevated circulating TNFalpha, such as Crohn's disease and Guillain-Barré syndrome. PMID:19403618

Motagally, Mohamed A; Lukewich, Mark K; Chisholm, Susan P; Neshat, Shadia; Lomax, Alan E

2009-06-01

70

A nanocomposite interconnecting layer for tandem small molecular organic photovoltaic cells  

NASA Astrophysics Data System (ADS)

A nanocomposite interconnecting layer of C60:LiF/Ag/MoOx had been applied in the tandem structure of organic photovoltaic cells to achieve high short circuit current (Jsc) and power conversion efficiency (PCE). The Jsc had been enhanced 40% after applying the nanocomposite interconnecting layer into a tandem structure compared to the conventional interconnecting layer of Bathocuproine (BCP)/Ag/MoOx. The improvement is due to the enhancement of the light absorption of the devices. A tandem device PCE of 3.04% was achieved by further improving the light absorption in the individual subcell units in the tandem structure by means of a bi-functional buffer layer of C60:LiF/BCP.

Luo, D. Y.; Yu, L. M.; Man, J. X.; Liu, Z.; Lu, Z. H.

2014-03-01

71

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

72

Nanocrystal bilayer for tandem catalysis  

Microsoft Academic Search

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the

Yusuke Yamada; Chia-Kuang Tsung; Wenyu Huang; Ziyang Huo; Susan E. Habas; Tetsuro Soejima; Cesar E. Aliaga; Gabor A. Somorjai; Peidong Yang

2011-01-01

73

Hybrid tandem photovoltaic devices with a transparent conductive interconnecting recombination layer  

SciTech Connect

Highlights: ? This work enhanced power conversion efficiency of the hybrid tandem solar cell from 1.0% to 2.6%. ? The interfacial series resistance of the tandem solar cell was eliminated by inserting ITO layer. ? This work shows the feasibility of the highly efficient hybrid tandem solar cells. -- Abstract: We demonstrate hybrid tandem photovoltaic devices with a transparent conductive interconnecting recombination layer. The series-connected hybrid tandem photovoltaic devices were developed by combining hydrogenated amorphous silicon (a-Si:H) and polymer-based organic photovoltaics (OPVs). In order to enhance the interfacial connection between the subcells, we employed highly transparent and conductive indium tin oxide (ITO) thin layer. By using the ITO interconnecting layer, the power conversion efficiency of the hybrid tandem solar cell was enhanced from 1.0% (V{sub OC} = 1.041 V, J{sub SC} = 2.97 mA/cm{sup 2}, FF = 32.3%) to 2.6% (V{sub OC} = 1.336 V, J{sub SC} = 4.65 mA/cm{sup 2}, FF = 41.98%) due to the eliminated interfacial series resistance.

Kim, Taehee; Choi, Jin Young; Jeon, Jun Hong; Kim, Youn-Su; Kim, Bong-Soo; Lee, Doh-Kwon; Kim, Honggon; Han, Seunghee [Solar Cell Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 136-791 (Korea, Republic of)] [Solar Cell Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 136-791 (Korea, Republic of); Kim, Kyungkon, E-mail: kimkk@ewha.ac.kr [Solar Cell Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 136-791 (Korea, Republic of) [Solar Cell Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 136-791 (Korea, Republic of); Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

2012-10-15

74

Tandem Filter Development for Thermophotovoltaic Energy Conversion from January 2003 to February 2006  

SciTech Connect

The intent of this report is to summarize the tandem filter development for spectral control of thermophotovoltaic energy conversion from January 2003 to the termination of the program in February 2006 and to closeout tandem filter development in order to capture the knowledge gained from the development effort. Over the last three years, the goals of the tandem filter development have been the following: (1) Study the limits of the design of the interference optical coatings component of a tandem filter in order to develop higher performance designs; (2) Enhance the fabrication process of the optical interference coatings to increase the fidelity with the intended design and allow more complex, higher performing designs; (3) Support TPV module testing by providing tandem filters and assembly assistance; (4) Identify and develop materials for optical interference coatings that are stable at higher temperatures than current materials; and (5) Improve the understanding of the directional and spectral reflectance and transmittance characterization of the completed tandem filters to insure the veracity of the characterization data and to provide useful feedback to the tandem filter development process. This development effort has been a collaboration between KAPL and its contracted development partner, Rugate Technologies Inc.

Fourspring PM

2007-03-19

75

Nanocrystal bilayer for tandem catalysis  

NASA Astrophysics Data System (ADS)

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts.

Yamada, Yusuke; Tsung, Chia-Kuang; Huang, Wenyu; Huo, Ziyang; Habas, Susan E.; Soejima, Tetsuro; Aliaga, Cesar E.; Somorjai, Gabor A.; Yang, Peidong

2011-05-01

76

"Nanocrystal bilayer for tandem catalysis"  

SciTech Connect

Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

2011-01-24

77

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

78

47 CFR 69.111 - Tandem-switched transport and tandem charge.  

Code of Federal Regulations, 2010 CFR

...index for the interconnection charge service category (defined in...tandem-switched transport charges within each study area used for the purpose of jurisdictional separations, in which interconnectors...tandem-switched transport charges within the study area...

2009-10-01

79

47 CFR 69.111 - Tandem-switched transport and tandem charge.  

Code of Federal Regulations, 2013 CFR

...index for the interconnection charge service category (defined in...tandem-switched transport charges within each study area used for the purpose of jurisdictional separations, in which interconnectors...tandem-switched transport charges within the study area...

2013-10-01

80

47 CFR 69.111 - Tandem-switched transport and tandem charge.  

Code of Federal Regulations, 2010 CFR

...index for the interconnection charge service category (defined in...tandem-switched transport charges within each study area used for the purpose of jurisdictional separations, in which interconnectors...tandem-switched transport charges within the study area...

2010-10-01

81

Short Tandem Repeat DNA Internet Database  

National Institute of Standards and Technology Data Gateway

SRD 130 Short Tandem Repeat DNA Internet Database (Web, free access)   Short Tandem Repeat DNA Internet Database is intended to benefit research and application of short tandem repeat DNA markers for human identity testing. Facts and sequence information on each STR system, population data, commonly used multiplex STR systems, PCR primers and conditions, and a review of various technologies for analysis of STR alleles have been included.

82

Tandem mirror technology demonstration facility  

SciTech Connect

This report describes a facility for generating engineering data on the nuclear technologies needed to build an engineering test reactor (ETR). The facility, based on a tandem mirror operating in the Kelley mode, could be used to produce a high neutron flux (1.4 MW/M/sup 2/) on an 8-m/sup 2/ test area for testing fusion blankets. Runs of more than 100 h, with an average availability of 30%, would produce a fluence of 5 mW/yr/m/sup 2/ and give the necessary experience for successful operation of an ETR.

Not Available

1983-10-01

83

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

84

Tandem junction amorphous silicon solar cells  

DOEpatents

An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

Hanak, Joseph J. (Lawrenceville, NJ)

1981-01-01

85

Diffractive intermediate layer enables broadband light trapping for high efficiency ultrathin c-Si tandem cells  

NASA Astrophysics Data System (ADS)

Light management through the intermediate reflector in the tandem cell configuration is of great practical importance for achieving high stable efficiency and also low cost production. So far, however, the intermediate reflectors employed currently are mainly focused on the light absorption enhancement of the top cell. Here, we present a diffractive intermediate layer that allows for light trapping over a broadband wavelength for the ultrathin c-Si tandem solar cell. Compared with the standard intermediate reflector, this nanoscale architectural intermediate layer results in a 35% and 21% remarkable enhancement of the light absorption in the top (400-800 nm) and bottom (800-1100 nm) cells simultaneously, and ultrathin c-Si tandem cells with impressive conversion efficiency of 13.3% are made on the glass substrate.

Li, Guijun; Ho, Jacob Y. L.; Li, He; Kwok, Hoi-Sing

2014-06-01

86

Halo recycler for the Tandem Mirror Experiment Upgrade  

SciTech Connect

The halow recycler is a mechanical device on the Tandem Mirror Experiment Upgrade (TMX-U) that is designed to increase the density at the plasma edge providing enhanced shielding of the core plasma from background neutrals. Each recycler body, which consists of coaxial annular cylinders and a adjacent plenum closely follows the magnetic flux tubes in the transition region of TMX-U. Each plenum is provided with gas feed and pressure measurement systems as well as Langmuir probes. This paper describes the design, fabrication, installation, and operation of these devices.

Brooksby, C.A.; Allen, S.L.; Pedrotti, L.R.; Simonen, T.C.; Wood, B.E.; Hsu, W.L.; Watkins, J.G.

1985-11-14

87

Strategy for tandem color registration  

NASA Astrophysics Data System (ADS)

This writing describes a strategy for color registration and motion control for tandem xerography. The strategy is based on an intelligent closed-loop controller which automatically calibrates the machine against repeatable errors and compensates for long term errors due to drift. Registration errors are measured by means of a dedicated sensor. Repeatable steady and periodic, errors are characterized at long intervals and compensated by feedforward techniques. Long term drifting errors are periodically detected and corrected. Feedback control is used to counteract unexpected and uncalibrated disturbances. Measurements taken on an experimental breadboard show that registration of four xerographic engines can be maintained to within 45 microns, and that color and gray banding can be eliminated. This limit of registration accuracy is mostly due to stretch of the intermediate belt under the action of image dependent transfer forces.

Castelli, Vittorio; Dejong, Jan; Williams, Lloyd

1996-03-01

88

Tandem Mirror Reactor Systems Code (Version I)  

SciTech Connect

A computer code was developed to model a Tandem Mirror Reactor. Ths is the first Tandem Mirror Reactor model to couple, in detail, the highly linked physics, magnetics, and neutronic analysis into a single code. This report describes the code architecture, provides a summary description of the modules comprising the code, and includes an example execution of the Tandem Mirror Reactor Systems Code. Results from this code for two sensitivity studies are also included. These studies are: (1) to determine the impact of center cell plasma radius, length, and ion temperature on reactor cost and performance at constant fusion power; and (2) to determine the impact of reactor power level on cost.

Reid, R.L.; Finn, P.A.; Gohar, M.Y.; Barrett, R.J.; Gorker, G.E.; Spampinaton, P.T.; Bulmer, R.H.; Dorn, D.W.; Perkins, L.J.; Ghose, S.

1985-09-01

89

Software Dependability in the Tandem Guardian System.  

National Technical Information Service (NTIS)

Based on extensive field failure data for Tandem's GUARDIAN operating system this paper discusses evaluation of the dependability of operational software. Software faults considered are major defects that result in processor failures and invoke backup pro...

I. Lee R. K. Iyer

1995-01-01

90

Advances in Tandem Mirror fusion power reactors  

Microsoft Academic Search

The Tandem Mirror exhibits several distinctive features which make the reactor embodiment of the principle very attractive: Simple low-technology linear central cell; steady-state operation; high-..beta.. operation; no driven current or disruptions; divertorless operation; direction conversion of end-loss power; low-surface heat loads; and advanced fusion fuel capability. In this paper, we examine these features in connection with two tandem mirror reactor

L. J. Perkins; B. G. Logan

1986-01-01

91

Enhanced Interferon Signaling Pathway in Oral Cancer Revealed by Quantitative Proteome Analysis of Microdissected Specimens Using 16O/18O Labeling and Integrated Two-dimensional LC-ESI-MALDI Tandem MS*  

PubMed Central

Oral squamous cell carcinoma (OSCC) remains one of the most common cancers worldwide, and the mortality rate of this disease has increased in recent years. No molecular markers are available to assist with the early detection and therapeutic evaluation of OSCC; thus, identification of differentially expressed proteins may assist with the detection of potential disease markers and shed light on the molecular mechanisms of OSCC pathogenesis. We performed a multidimensional 16O/18O proteomics analysis using an integrated ESI-ion trap and MALDI-TOF/TOF MS system and a computational data analysis pipeline to identify proteins that are differentially expressed in microdissected OSCC tumor cells relative to adjacent non-tumor epithelia. We identified 1233 unique proteins in microdissected oral squamous epithelia obtained from three pairs of OSCC specimens with a false discovery rate of <3%. Among these, 977 proteins were quantified between tumor and non-tumor cells. Our data revealed 80 dysregulated proteins (53 up-regulated and 27 down-regulated) when a 2.5-fold change was used as the threshold. Immunohistochemical staining and Western blot analyses were performed to confirm the overexpression of 12 up-regulated proteins in OSCC tissues. When the biological roles of 80 differentially expressed proteins were assessed via MetaCore™ analysis, the interferon (IFN) signaling pathway emerged as one of the most significantly altered pathways in OSCC. As many as 20% (10 of 53) of the up-regulated proteins belonged to the IFN-stimulated gene (ISG) family, including ubiquitin cross-reactive protein (UCRP)/ISG15. Using head-and-neck cancer tissue microarrays, we determined that UCRP is overexpressed in the majority of cheek and tongue cancers and in several cases of larynx cancer. In addition, we found that IFN-? stimulates UCRP expression in oral cancer cells and enhances their motility in vitro. Our findings shed new light on OSCC pathogenesis and provide a basis for the future development of novel biomarkers.

Chi, Lang-Ming; Lee, Chien-Wei; Chang, Kai-Ping; Hao, Sheng-Po; Lee, Hang-Mao; Liang, Ying; Hsueh, Chuen; Yu, Chia-Jung; Lee, I-Neng; Chang, Yin-Ju; Lee, Shih-Ying; Yeh, Yuan-Ming; Chang, Yu-Sun; Chien, Kun-Yi; Yu, Jau-Song

2009-01-01

92

Enhanced interferon signaling pathway in oral cancer revealed by quantitative proteome analysis of microdissected specimens using 16O/18O labeling and integrated two-dimensional LC-ESI-MALDI tandem MS.  

PubMed

Oral squamous cell carcinoma (OSCC) remains one of the most common cancers worldwide, and the mortality rate of this disease has increased in recent years. No molecular markers are available to assist with the early detection and therapeutic evaluation of OSCC; thus, identification of differentially expressed proteins may assist with the detection of potential disease markers and shed light on the molecular mechanisms of OSCC pathogenesis. We performed a multidimensional (16)O/(18)O proteomics analysis using an integrated ESI-ion trap and MALDI-TOF/TOF MS system and a computational data analysis pipeline to identify proteins that are differentially expressed in microdissected OSCC tumor cells relative to adjacent non-tumor epithelia. We identified 1233 unique proteins in microdissected oral squamous epithelia obtained from three pairs of OSCC specimens with a false discovery rate of <3%. Among these, 977 proteins were quantified between tumor and non-tumor cells. Our data revealed 80 dysregulated proteins (53 up-regulated and 27 down-regulated) when a 2.5-fold change was used as the threshold. Immunohistochemical staining and Western blot analyses were performed to confirm the overexpression of 12 up-regulated proteins in OSCC tissues. When the biological roles of 80 differentially expressed proteins were assessed via MetaCore analysis, the interferon (IFN) signaling pathway emerged as one of the most significantly altered pathways in OSCC. As many as 20% (10 of 53) of the up-regulated proteins belonged to the IFN-stimulated gene (ISG) family, including ubiquitin cross-reactive protein (UCRP)/ISG15. Using head-and-neck cancer tissue microarrays, we determined that UCRP is overexpressed in the majority of cheek and tongue cancers and in several cases of larynx cancer. In addition, we found that IFN-beta stimulates UCRP expression in oral cancer cells and enhances their motility in vitro. Our findings shed new light on OSCC pathogenesis and provide a basis for the future development of novel biomarkers. PMID:19297561

Chi, Lang-Ming; Lee, Chien-Wei; Chang, Kai-Ping; Hao, Sheng-Po; Lee, Hang-Mao; Liang, Ying; Hsueh, Chuen; Yu, Chia-Jung; Lee, I-Neng; Chang, Yin-Ju; Lee, Shih-Ying; Yeh, Yuan-Ming; Chang, Yu-Sun; Chien, Kun-Yi; Yu, Jau-Song

2009-07-01

93

Chromatin tandem affinity purification sequencing  

PubMed Central

Chromatin immunoprecipitation coupled with ultra-high-throughput sequencing (ChIP-seq) is a widely used method for mapping the interactions of proteins with DNA. However, the requirements for ChIP-grade antibodies impede wider application of this method, and variations in results can be high owing to differences in affinity and cross-reactivity of antibodies. Therefore, we developed chromatin tandem affinity purification (ChTAP) as an effective alternative to ChIP. Through the use of affinity tags and reagents that are identical for all proteins investigated, ChTAP enables one to directly compare the binding between different transcription factors and to directly assess the background in control experiments. Thus, ChTAP -seq can be used to rapidly map the genome-wide binding of multiple DNA -binding proteins in a wide range of cell types. ChTAP can be completed in 3–4 d, starting from cross-linking of chromatin to purification of ChIP DNA.

Soleimani, Vahab D; Palidwor, Gareth A; Ramachandran, Parameswaran; Perkins, Theodore J; Rudnicki, Michael A

2014-01-01

94

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

95

Tandem constructs to mitigate transgene persistence: tobacco as a model.  

PubMed

Some transgenic crops can introgress genes into other varieties of the crop, to related weeds or themselves remain as 'volunteer' weeds, potentially enhancing the invasiveness or weediness of the resulting offspring. The presently suggested mechanisms for transgene containment allow low frequency of gene release (leakage), requiring the mitigation of continued spread. Transgenic mitigation (TM), where a desired primary gene is tandemly coupled with mitigating genes that are positive or neutral to the crop but deleterious to hybrids and their progeny, was tested as a mechanism to mitigate transgene introgression. Dwarfism, which typically increases crop yield while decreasing the ability to compete, was used as a mitigator. A construct of a dominant ahasR (acetohydroxy acid synthase) gene conferring herbicide resistance in tandem with the semidominant mitigator dwarfing Delta gai (gibberellic acid-insensitive) gene was transformed into tobacco (Nicotiana tabacum). The integration and the phenotypic stability of the tandemly linked ahasR and Delta gai genomic inserts in later generations were confirmed by polymerase chain reaction. The hemizygous semidwarf imazapyr-resistant TM T1 (= BC1) transgenic plants were weak competitors when cocultivated with wild type segregants under greenhouse conditions and without using the herbicide. The competition was most intense at close spacings typical of weed offspring. Most dwarf plants interspersed with wild type died at 1-cm, > 70% at 2.5-cm and 45% at 5-cm spacing, and the dwarf survivors formed no flowers. At 10-cm spacing, where few TM plants died, only those TM plants growing at the periphery of the large cultivation containers formed flowers, after the wild type plants terminated growth. The highest reproductive TM fitness relative to the wild type was 17%. The results demonstrate the suppression of crop-weed hybrids when competing with wild type weeds, or such crops as volunteer weeds, in seasons when the selector (herbicide) is not used. The linked unfitness would be continuously manifested in future generations, keeping the transgene at a low frequency. PMID:14871372

Al-Ahmad, Hani; Galili, Shmuel; Gressel, Jonathan

2004-03-01

96

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

2012-08-01

97

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

98

Tandemly Arrayed Genes in Vertebrate Genomes  

PubMed Central

Tandemly arrayed genes (TAGs) are duplicated genes that are linked as neighbors on a chromosome, many of which have important physiological and biochemical functions. Here we performed a survey of these genes in 11 available vertebrate genomes. TAGs account for an average of about 14% of all genes in these vertebrate genomes, and about 25% of all duplications. The majority of TAGs (72–94%) have parallel transcription orientation (i.e., they are encoded on the same strand) in contrast to the genome, which has about 50% of its genes in parallel transcription orientation. The majority of tandem arrays have only two members. In all species, the proportion of genes that belong to TAGs tends to be higher in large gene families than in small ones; together with our recent finding that tandem duplication played a more important role than retroposition in large families, this fact suggests that among all types of duplication mechanisms, tandem duplication is the predominant mechanism of duplication, especially in large families. Finally, several species have a higher proportion of large tandem arrays that are species-specific than random expectation.

Pan, Deng; Zhang, Liqing

2008-01-01

99

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

100

Structural basis for tandem L27 domain-mediated polymerization.  

PubMed

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 ?A-?B and helix ?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. PMID:20702775

Yang, Xue; Xie, Xingqiao; Chen, Liu; Zhou, Hao; Wang, Zheng; Zhao, Weijing; Tian, Ran; Zhang, Rongguang; Tian, Changlin; Long, Jiafu; Shen, Yuequan

2010-12-01

101

A mechanistic insight into a proteasome-independent constitutive inhibitor kappaBalpha (IkappaBalpha) degradation and nuclear factor kappaB (NF-kappaB) activation pathway in WEHI-231 B-cells.  

PubMed Central

Inducible activation of the transcription factor NF-kappaB (nuclear factor kappaB) is classically mediated by proteasomal degradation of its associated inhibitors, IkappaBalpha (inhibitory kappaBalpha) and IkappaBbeta. However, certain B-lymphocytes maintain constitutively nuclear NF-kappaB activity (a p50-c-Rel heterodimer) which is resistant to inhibition by proteasome inhibitors. This activity in the WEHI-231 B-cell line is associated with continual and preferential degradation of IkappaBalpha, which is also unaffected by proteasome inhibitors. Pharmacological studies indicated that there was a correlation between inhibition of IkappaBalpha degradation and constitutive p50-c-Rel activity. Domain analysis of IkappaBalpha by deletion mutagenesis demonstrated that an N-terminal 36-amino-acid sequence of IkappaBalpha represented an instability determinant for constitutive degradation. Moreover, domain grafting studies indicated that this sequence was sufficient to cause IkappaBbeta, but not chloramphenicol acetyltransferase, to be rapidly degraded in WEHI-231 B-cells. However, this sequence was insufficient to target IkappaBbeta to the non-proteasome degradation pathway, suggesting that there was an additional cis-element(s) in IkappaBalpha that was required for complete targeting. Nevertheless, the NF-kappaB pool associated with IkappaBbeta now became constitutively active by virtue of IkappaBbeta instability in these cells. These findings further support the notion that IkappaB instability governs the maintenance of constitutive p50-c-Rel activity in certain B-cells via a unique degradation pathway.

Shumway, Stuart D; Miyamoto, Shigeki

2004-01-01

102

Constitutive nuclear factor kappaB activity is required to elicit interferon-gamma-induced expression of chemokine CXC ligand 9 (CXCL9) and CXCL10 in human tumour cell lines.  

PubMed Central

CXC ligand 10 (CXCL10) and CXCL9 are chemoattractants for activated T cells and possess angiostatic activity. Both CXCL9 and CXCL10 have been considered as important components for the anti-tumour activities of interferon-gamma (IFNgamma) and interleukin-12 in animal models. In this article we show that the CXCL9 and CXCL10 genes in some types of human tumour cell lines are not inducible by IFNgamma and we describe experiments designed to explore the molecular mechanisms involved in this impaired induction. The human oral squamous carcinoma line Ca9-22 and the glioma line A172 failed to express CXCL9 and CXCL10 mRNAs in response to IFNgamma, whereas other carcinoma lines including HSC-2 did express these mRNAs. Production of these chemokine proteins was also impaired in Ca9-22 cells. The impaired expression was not due to any deficiency in the IFNgamma/signal transducer and activator of transcription 1 (STAT1)-dependent signalling pathway. Instead, analysis of nuclear factor kappaB (NF-kappaB) activity revealed that the constitutive low level of NF-kappaB activity, which is seen in cells that express these chemokines, was absent in Ca9-22 and A172 cells. Activation of NF-kappaB in Ca9-22 cells restored the expression of IFNgamma-stimulated CXCL9 and CXCL10 mRNAs. In contrast, inhibition of the constitutive NF-kappaB in HSC-2 cells by adenovirus-mediated gene transfer of a dominant-negative IkappaBalpha suppressed the IFNgamma-induced expression of the CXCL9 and CXCL10 mRNAs. These results indicate that constitutive NF-kappaB activity, which is often associated with tumour development, is required for the induced expression of CXCL9 and CXCL10 genes in human tumour cell lines in response to IFNgamma.

Hiroi, Miki; Ohmori, Yoshihiro

2003-01-01

103

Lack of p53 Decreases Basal Oxidative Stress Levels in the Brain Through Upregulation of Thioredoxin-1, Biliverdin Reductase-A, Manganese Superoxide Dismutase, and Nuclear Factor Kappa-B  

PubMed Central

Abstract Aims: The basal oxidative and nitrosative stress levels measured in cytosol, mitochondria, and nuclei as well as in the whole homogenate obtained from the brain of wild type (wt) and p53 knockout [p53(?/?)] mice were evaluated. We hypothesized that the loss of p53 could trigger the activation of several protective mechanisms such as those involving thioredoxin-1 (Thio-1), the heme-oxygenase-1/biliverdin reductase-A (HO-1/BVR-A) system, manganese superoxide dismutase (MnSOD), the IkB kinase type ? (IKK?)/nuclear factor kappa-B (NF-kB), and the nuclear factor-erythroid 2 (NF-E2) related factor 2 (Nrf-2). Results: A decrease of protein carbonyls, protein-bound 4-hydroxy-2-nonenal (HNE), and 3-nitrotyrosine (3-NT) was observed in the brain from p53(?/?) mice compared with wt. Furthermore, we observed a significant increase of the expression levels of Thio-1, BVR-A, MnSOD, IKK?, and NF-kB. Conversely a significant decrease of Nrf-2 protein levels was observed in the nuclear fraction isolated from p53(?/?) mice. No changes were found for HO-1. Innovation: This is the first study of basal oxidative/nitrosative stress in in vivo conditions of brain obtained from p53(?/?) mice. New insights into the role of p53 in oxidative stress have been gained. Conclusion: We demonstrated, for the first time, that the lack of p53 reduces basal oxidative stress levels in mice brain. Due to the pivotal role that p53 plays during cellular stress response our results provide new insights into novel therapeutic strategies to modulate protein oxidation and lipid peroxidation having p53 as a target. The implications of this work are profound, particularly for neurodegenerative disorders. Antioxid. Redox Signal. 16, 1407–1420.

Barone, Eugenio; Cenini, Giovanna; Sultana, Rukhsana; Di Domenico, Fabio; Fiorini, Ada; Perluigi, Marzia; Noel, Teresa; Wang, Chi; Mancuso, Cesare; St. Clair, Daret K.

2012-01-01

104

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

105

Teaching in tandem-running ants.  

PubMed

The ant Temnothorax albipennis uses a technique known as tandem running to lead another ant from the nest to food--with signals between the two ants controlling both the speed and course of the run. Here we analyse the results of this communication and show that tandem running is an example of teaching, to our knowledge the first in a non-human animal, that involves bidirectional feedback between teacher and pupil. This behaviour indicates that it could be the value of information, rather than the constraint of brain size, that has influenced the evolution of teaching. PMID:16407943

Franks, Nigel R; Richardson, Tom

2006-01-12

106

High voltage series connected tandem junction solar battery  

DOEpatents

A high voltage series connected tandem junction solar battery which comprises a plurality of strips of tandem junction solar cells of hydrogenated amorphous silicon having one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon, arranged in a tandem configuration, can have the same bandgap or differing bandgaps. The tandem junction strip solar cells are series connected to produce a solar battery of any desired voltage.

Hanak, Joseph J. (Lawrenceville, NJ)

1982-01-01

107

The soy isoflavone genistein blunts nuclear factor kappa-B, MAPKs and TNF-? activation and ameliorates muscle function and morphology in mdx mice.  

PubMed

Several lines of evidence suggest a detrimental role of the nuclear factor-?B (NF-?B) activation in the dystrophic process. We showed in previous studies that its inhibition through drugs with antioxidant properties, have beneficial effects in mdx mice. We tested whether genistein, a well-known isoflavone, inhibitor of NF-?B, MAPK and TNF-? and readily available for clinical use, could have a beneficial effect in mdx mice in comparison with methylprednisolone, the gold standard treatment for DMD patients. Five-week old mdx mice received for five weeks: genistein (daily or 3-times/week), methylprednisolone or vehicle. Genistein treatment: (1) increased forelimb strength and strength normalized to weight; (2) reduced serum creatine-kinase levels; (3) reduced markers of oxidative stress; (4) reduced muscle necrosis and enhanced regeneration. The positive results were more evident with the daily administration of genistein and were comparable to the effect of corticosteroids. Our data support the novel hypothesis that, as other more specific therapeutic approaches are still under development, this soy-derived compound is a promising option to be further investigated in dystrophic process. PMID:21658942

Messina, Sonia; Bitto, Alessandra; Aguennouz, M'hammed; Vita, Gian Luca; Polito, Francesca; Irrera, Natasha; Altavilla, Domenica; Marini, Herbert; Migliorato, Alba; Squadrito, Francesco; Vita, Giuseppe

2011-08-01

108

Sargassum fusiforme polysaccharide activates nuclear factor kappa-B (NF-?B) and induces cytokine production via Toll-like receptors.  

PubMed

This study was designed to investigate the mechanism of macrophage activation by the Sargassum fusiforme polysaccharide (SFPS). As a result, SFPS significantly enhanced cytokines and nitric oxide (NO) productions in peritoneal macrophages, and stimulated macrophages to produce the cytokines and NO through the induction of their genes expression. The pretreatment of peritoneal macrophages with special antibodies [Toll-like receptors (TLRs) antibody] significantly blocked SFPS-induced tumor necrosis factor alpha (TNF-?) and NO production. Furthermore, pyrrolidine dithiocarbamate (PDTC), a specific inhibitor of NF-?B, effectively suppressed SFPS-induced TNF-? and interleukin 1? (IL-1?) secretion in peritoneal macrophages, indicating that SFPS stimulated macrophages to produce cytokines through the NF-?B pathway and the result was further confirmed by the experiment of Western blotting (WB) and confocal laser scanning microscope (CLSM). Taken together, these results suggest that SFPS-mediated induction of cytokines and NO production in macrophages is mediated, at least in part, by TLRs/NF-?B signaling pathway. PMID:24708959

Chen, Xiaoming; Yu, Guoqing; Fan, Sairong; Bian, Manman; Ma, Huijun; Lu, Jianxin; Jin, Liqin

2014-05-25

109

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

110

beta-D-Glucoside suppresses tumor necrosis factor-induced activation of nuclear transcription factor kappaB but potentiates apoptosis.  

PubMed

Mangiferin, a natural polyphenol is known to exhibit anti-inflammatory, antioxidant, and antiviral effects. However the molecular mechanism underlying these effects has not been well characterized. Because NF-kappaB plays an important role in these processes, it is possible that mangiferin modulates NF-kappaB activation. Our results show that mangiferin blocks tumor necrosis factor (TNF)-induced NF-kappaB activation and NF-kappaB-dependent genes like ICAM1 and COX2. The effect was mediated through inhibition of IKK activation and subsequent blocking of phosphorylation and degradation of IkappaBalpha. In addition, mangiferin inhibits TNF-induced p65 phosphorylation as well as translocation to the nucleus and also inhibits NF-kappaB activation induced by other inflammatory agents like PMA, ceramide, and SA-LPS. Mangiferin, similar to the other known antioxidants, NAC and PDTC, inhibits TNF-induced reactive oxygen intermediate (ROI) generation. Since intracellular glutathione (GSH) levels are known to modulate NF-kappaB levels, we measured the levels of GSH. Mangiferin enhances glutathione level by almost 2-fold more than other anti-oxidants, and at the same time it decreases the levels of GSSG and increases the activity of catalase. Depletion of GSH by buthionine sulfoximine led to a significant reversal of mangiferin effect. Hence mangiferin with its ability to inhibit NF-kappaB and increase the intracellular GSH levels may prove to be a potent drug for anti-inflammatory and antioxidant therapy. Mangiferin-mediated down-regulation of NF-kappaB also potentiates chemotherapeutic agent-mediated cell death, suggesting a role in combination therapy for cancer. PMID:15161907

Sarkar, Abira; Sreenivasan, Yashin; Ramesh, Govindarajan T; Manna, Sunil K

2004-08-01

111

Nuclear factor kappaB cooperates with c-Myc in promoting murine hepatocyte survival in a manner independent of p53 tumor suppressor function.  

PubMed

The nuclear factor-kappaB (NF-kappaB)/Rel family of transcription factors has been implicated in promoting hepatocyte survival during development and liver regeneration following partial hepatectomy. Inhibition of NF-kappaB/Rel activity by microinjection of the specific inhibitor IkappaB-alpha induces apoptosis in a nontransformed normal murine hepatocyte (NMH) cell line. Here, we demonstrate that apoptosis resulting from such inhibition requires down-regulation of the c-Myc proto-oncoprotein and occurs independently of p53 tumor suppressor function. NMH cells plated at low density displayed low sensitivity to IkappaB-alpha-induced apoptosis and high levels of c-Myc protein expression. Comicroinjection of IkappaB-alpha with the c-Myc antagonist Mad1-glutathione S-transferase fusion protein greatly enhanced cell death. In addition, transient cotransfection of low-density NMH and AML12 hepatocytes with vectors expressing IkappaB-alpha and antisense c-myc transcripts promoted cell death. Conversely, ectopic c-myc expression significantly decreased the extent of cell death in NMH cells plated at saturating density, which were characterized by very low levels of c-Myc and high susceptibility to NF-kappaB inhibition-induced cell death. Finally, IkappaB-alpha-induced apoptosis was unaffected in NMH cells expressing a dominant negative p53 protein. Thus, NF-kappaB cooperates with c-Myc in promoting murine hepatocyte survival in a manner independent of p53 tumor suppressor activity. PMID:10359010

Bellas, R E; Sonenshein, G E

1999-05-01

112

Improvement of the short-circuit current density and efficiency in micromorph tandem solar cells by an anti-reflection layer  

Microsoft Academic Search

An anti-reflection layer has been fabricated and applied in micromorph tandem (a-Si:H\\/?c-Si:H) solar cells. In this work, the porous anti-reflection layers are produced on glass substrates by plasma enhanced chemical vapor deposition using a CF4 and O2 gas mixture. The process is simple and easily controlled. The tandem solar cells with the anti-reflection layer show the increased short-circuit current density

Ping-Kuan Chang; Po-Tsung Hsieh; Fu-Ji Tsai; Chun-Hsiung Lu; Chih-Hung Yeh; Mau-Phon Houng

2011-01-01

113

Tandem Mirror Reactor Power Balance Studies.  

National Technical Information Service (NTIS)

A tandem mirror reactor (TMR) power plant balance model has been developed and is now being used as a computer aid for performing parametric studies. End-cell power injection into the plasma and the physics thermal Q are used to determine the fusion power...

G. E. Gorker L. J. Perkins

1985-01-01

114

Tandem connected submersible oil well pump motors  

SciTech Connect

Submersible electric motors for pumping fluid from wells are assembled together in tandem relationship for increasing total output horsepower. Means are provided to make electrical connections just prior to assembly and interconnect the oil flow corridors between motors during assembly. Precompressed springloaded thrust bearings compensate for shaft length changes and dampen vibrations. The oil circulation corridors include filtration.

Carle, J.T.; Wilson, B.L.

1982-09-21

115

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

116

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

117

Swept Inducer Blades With Tandem Radial Slots  

NASA Technical Reports Server (NTRS)

Slanted radial slots at tandem positions along approximate streamlines incorporated into swept inducer blades in turbopump, according to proposal. With suitable design, slots suppress low-frequency oscillations induced by cavitation, without causing excessive loss of inducer head. Slots cut into solid blades by wire electrical-discharge machining.

Meng, Sen Y.

1995-01-01

118

Status of BINP proton tandem accelerator  

NASA Astrophysics Data System (ADS)

The status of a unique 2.0 MeV, 10 mA proton tandem accelerator with vacuum insulation is presented. The accelerator is intended to be used in facilities generating resonant gamma rays for explosives detection and epithermal neutrons for boron neutron-capture therapy of brain tumors. A magnetically coupled DC voltage multiplier derived from an industrial ELV-type electron accelerator is used as a high voltage source for the accelerator. A dc high current negative ion source has been developed for injection into the tandem. In the tandem accelerator there is set of nested potential electrodes with openings which form a channel for accelerating the negative hydrogen ion beam and subsequently accelerating the proton beam after stripping in the gas target. The electrodes are connected to a high voltage feedthrough insulator to which required potentials are applied from the high voltage power supply by means of a resistor voltage divider. In the paper the first experimental results obtained with the vacuum insulated tandem accelerator are also given.

Burdakov, A.; Davydenko, V.; Dolgushin, V.; Dranichnikov, A.; Ivanov, A.; Farrell, J. P.; Khilchenko, A.; Kobets, V.; Konstantinov, S.; Krivenko, A.; Kudryavtsev, A.; Tiunov, M.; Savkin, V.; Shirokov, V.; Sorokin, I.

2007-08-01

119

Error-burst detection with tandem CRCs  

Microsoft Academic Search

The authors investigate the efficacy of using two different cyclic redundancy check (CRC) codes in tandem to increase error-burst detecting capability. For a set of pairs of CRCs which are used in standards, it is found that the guaranteed detectable burst length is less than the sum of the individual guaranteed detectable burst lengths, but not much less. Thus strengthened

J. E. Mazo; B. R. Saltzberg

1991-01-01

120

Evolution of the tandem mirror reactor concept  

SciTech Connect

We discuss the evolution of the tandem mirror reactor concept from the original conceptual reactor design (1977) through the first application of the thermal barrier concept to a reactor design (1979) to the beginning of the Mirror Advanced Reactor Study (1982).

Carlson, G.A.; Logan, B.G.

1982-03-09

121

Software Dependability in the Tandem GUARDIAN System  

Microsoft Academic Search

Based on extensive field failure data for Tandem's GUARDIAN operating system, the paper discusses evaluation of the dependability of operational software. Software faults considered are major defects that result in processor failures and invoke backup processes to take over. The paper categorizes the underlying causes of software failures and evaluates the effectiveness of the process pair technique in tolerating software

Inhwan Lee; Ravishankar K. Iyer

1995-01-01

122

Inverted Three-Junction Tandem Thermophotovoltaic Modules  

NASA Technical Reports Server (NTRS)

An InGaAs-based three-junction (3J) tandem thermophotovoltaic (TPV) cell has been investigated to utilize more of the blackbody spectrum (from a 1,100 C general purpose heat source GPHS) efficiently. The tandem consists of three vertically stacked subcells, a 0.74-eV InGaAs cell, a 0.6- eV InGaAs cell, and a 0.55-eV InGaAs cell, as well as two interconnecting tunnel junctions. A greater than 20% TPV system efficiency was achieved by another group with a 1,040 C blackbody using a single-bandgap 0.6- eV InGaAs cell MIM (monolithic interconnected module) (30 lateral junctions) that delivered about 12 V/30 or 0.4 V/junction. It is expected that a three-bandgap tandem MIM will eventually have about 3 this voltage (1.15 V) and about half the current. A 4 A/cm2 would be generated by a single-bandgap 0.6-V InGaAs MIM, as opposed to the 2 A/cm2 available from the same spectrum when split among the three series-connected junctions in the tandem stack. This would then be about a 50% increase (3xVoc, 0.5xIsc) in output power if the proposed tandem replaced the single- bandgap MIM. The advantage of the innovation, if successful, would be a 50% increase in power conversion efficiency from radioisotope heat sources using existing thermophotovoltaics. Up to 50% more power would be generated for radioisotope GPHS deep space missions. This type of InGaAs multijunction stack could be used with terrestrial concentrator solar cells to increase efficiency from 41 to 45% or more.

Wojtczuk, Steven

2012-01-01

123

Highly efficient bipolar connecting layers for tandem organic light-emitting devices  

NASA Astrophysics Data System (ADS)

A highly efficient tandem organic light-emitting device (OLED) has been fabricated by using an effective bipolar connecting layer structure. The connecting layers were made up of a layer of magnesium (Mg): 2,7-dipyrenyl-9,9-diphenyl fluorene (N-DPF) and a layer of tungsten trioxide (WO3). Such a connecting layer structure permits efficient opposite holes and electrons flowing into two adjacent emitting units. The current efficiency of the two-unit tandem device can be dramatically enhanced by more than four times compared with that of the conventional single-unit device. At 60 mA/cm2, the current efficiency of the tandem OLED using the connecting layers of Mg: N-DPF/WO3 was about 8.15 cd/A. The results can be marked as a breakthrough approach to improve the current efficiency and brightness of OLEDs. Furthermore, a model of the carrier tunneling into light-emitting units is proposed based on carrier balance and field-assisted tunneling. It indicates that the connecting layer structure functions as the origin of high efficiency for the tandem OLEDs.

Niu, L.; Guan, Y.; Kong, C.; Cui, Y.; Ren, Y.; Tao, S.; Zhou, J.; Yu, J.

2011-12-01

124

Experimental verification of optically optimized CuGaSe2 top cell for improving chalcopyrite tandems  

NASA Astrophysics Data System (ADS)

An efficient tandem solar cell requires a top cell which is highly transparent below the energy gap of its absorber. Previously we had reported on a theoretically optimized CuGaSe2top cell stack based on realistic material properties. It promised a significant increase in optical transparency and, consequently, enhanced CuGaSe2/Cu(In,Ga)Se2tandem efficiency. Here we present the first steps taken towards the experimental realization of this optimized tandem. We started with a mechanically stacked device which achieved 8.5% efficiency. Optical measurements of the improved top cells and corresponding photo current densities of the filtered bottom cell are reported. The experimental findings are in agreement with the optical modeling. These data are used to assess the level of tandem performance that could be accomplished in the near future and to discuss the priorities of further research. This article has been previously published in PV Direct, the former name of EPJ Photovoltaics.

Schmid, M.; Caballero, R.; Klenk, R.; Kr?, J.; Rissom, T.; Topi, M.; Lux-Steiner, M. Ch.

2010-07-01

125

Dye Sensitized Tandem Photovoltaic Cells  

SciTech Connect

This work provided a new way to look at photoelectrochemical cells and their performance. Although thought of as low efficiency, a the internal efficiency of a 9% global efficiency dye sensitized solar cell is approximately equal to an 18% efficient silicon cell when each is compared to their useful spectral range. Other work undertaken with this contract also reported the first growth oriented titania and perovskite columns on a transparent conducting oxide. Other work has shown than significant performance enhancement in the performance of dye sensitized solar cells can be obtained through the use of coupling inverse opal photonic crystals to the nanocrystalline dye sensitized solar cell. Lastly, a quick efficient method was developed to bond titanium foils to transparent conducting oxide substrates for anodization.

Barber, Greg D.

2009-12-21

126

Probabilistic approaches to alignment with tandem repeats  

PubMed Central

Background Short tandem repeats are ubiquitous in genomic sequences and due to their complex evolutionary history pose a challenge for sequence alignment tools. Results To better account for the presence of tandem repeats in pairwise sequence alignments, we propose a simple tractable pair hidden Markov model that explicitly models their presence. Using the framework of gain functions, we design several optimization criteria for decoding this model and describe resulting decoding algorithms, ranging from the traditional Viterbi and posterior decoding to block-based decoding algorithms tailored to our model. We compare the accuracy of individual decoding algorithms on simulated and real data and find that our approach is superior to the classical three-state pair HMM. Conclusions Our study illustrates versatility of pair hidden Markov models coupled with appropriate decoding criteria as a modeling tool for capturing complex sequence features.

2014-01-01

127

Mechanically stacked concentrator tandem solar cells  

NASA Technical Reports Server (NTRS)

Four-terminal mechanically stacked solar cells were developed for advanced space arrays with line-focus reflective concentrators. The top cells are based on AlGaAs/GaAs multilayer heterostructures prepared by low temperature liquid phase epitaxy. The bottom cells are based on heteroepitaxial InP/InGaAs liquid phase epitaxy or on homo-junction GaSb, Zn-diffused structures. The sum of the highest reached efficiencies of the top and bottom cells is 29.4 percent. The best four-terminal tandems have an efficiency of 27 to 28 percent. Solar cells were irradiated with 1 MeV electrons and their performances were determined as a function of fluence up to 10(exp 16) cm(exp-2). It was shown that the radiation resistance of developed tandem cells is similar to the most radiative stable AlGaAs/GaAs cells with a thin p-GaAs photoactive layer.

Andreev, V. M.; Rumyantsev, V. D.; Karlina, L. B.; Kazantsev, A. B.; Khvostikov, V. P.; Shvarts, M. Z.; Sorokina, S. V.

1995-01-01

128

Nucleic acid recognition by tandem helical repeats.  

PubMed

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. PMID:22154606

Rubinson, Emily H; Eichman, Brandt F

2012-02-01

129

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

130

Tandem microwave waste remediation and decontamination system  

DOEpatents

The invention discloses a tandem microwave system consisting of a primary chamber in which microwave energy is used for the controlled combustion of materials. A second chamber is used to further treat the off-gases from the primary chamber by passage through a susceptor matrix subjected to additional microwave energy. The direct microwave radiation and elevated temperatures provide for significant reductions in the qualitative and quantitative emissions of the treated off gases. The tandem microwave system can be utilized for disinfecting wastes, sterilizing materials, and/or modifying the form of wastes to solidify organic or inorganic materials. The simple design allows on-site treatment of waste by small volume waste generators.

Wicks, George G. (North Aiken, SC); Clark, David E. (Gainesville, FL); Schulz, Rebecca L. (Gainesville, FL)

1999-01-01

131

Short Tandem Repeat DNA Internet Database  

NSDL National Science Digital Library

This website contains comprehensive information relating to forensic DNA analysis. It has material from an introductory to an advanced level on forensic DNA technology. The material provides general information on DNA markers that are of interest to human identification. The site contains both introductory and in-depth discussions of short tandem repeats (STRs) and other DNA markers currently used by the forensic community. Powerpoint and PDF presentations on STR training material are available and can be readily downloaded.

2011-04-08

132

Current and lattice matched tandem solar cell  

DOEpatents

A multijunction (cascade) tandem photovoltaic solar cell device is fabricated of a Ga.sub.x In.sub.1-x P (0.505.ltoreq.X.ltoreq.0.515) top cell semiconductor lattice matched to a GaAs bottom cell semiconductor at a low-resistance heterojunction, preferably a p+/n+ heterojunction between the cells. The top and bottom cells are both lattice matched and current matched for high efficiency solar radiation conversion to electrical energy.

Olson, Jerry M. (Lakewood, CO)

1987-01-01

133

TandEM: Titan and Enceladus mission  

Microsoft Academic Search

TandEM was proposed as an L-class (large) mission in response to ESA’s Cosmic Vision 2015–2025 Call, and accepted for further\\u000a studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds\\u000a tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini–Huygens\\u000a mission. These

A. Coustenis; S. K. Atreya; T. Balint; R. H. Brown; M. K. Dougherty; F. Ferri; M. Fulchignoni; D. Gautier; R. A. Gowen; C. A. Griffith; L. I. Gurvits; R. Jaumann; Y. Langevin; M. R. Leese; J. I. Lunine; C. P. McKay; X. Moussas; I. Müller-Wodarg; F. Neubauer; T. C. Owen; F. Raulin; E. C. Sittler; F. Sohl; C. Sotin; G. Tobie; T. Tokano; E. P. Turtle; J.-E. Wahlund; J. H. Waite; K. H. Baines; J. Blamont; A. J. Coates; I. Dandouras; T. Krimigis; E. Lellouch; R. D. Lorenz; A. Morse; C. C. Porco; M. Hirtzig; J. Saur; T. Spilker; J. C. Zarnecki; E. Choi; N. Achilleos; R. Amils; P. Annan; D. H. Atkinson; Y. Bénilan; C. Bertucci; B. Bézard; G. L. Bjoraker; M. Blanc; L. Boireau; J. Bouman; M. T. Capria; E. Chassefière; P. Coll; M. Combes; J. F. Cooper; A. Coradini; F. Crary; T. Cravens; I. A. Daglis; E. de Angelis; C. de Bergh; I. de Pater; C. Dunford; G. Durry; O. Dutuit; D. Fairbrother; F. M. Flasar; A. D. Fortes; R. Frampton; M. Fujimoto; M. Galand; O. Grasset; M. Grott; T. Haltigin; A. Herique; F. Hersant; H. Hussmann; W. Ip; R. Johnson; E. Kallio; S. Kempf; M. Knapmeyer; W. Kofman; R. Koop; T. Kostiuk; N. Krupp; M. Küppers; H. Lammer; L.-M. Lara; P. Lavvas; S. Le Mouélic; S. Lebonnois; S. Ledvina; J. Li; T. A. Livengood; R. M. Lopes; J.-J. Lopez-Moreno; D. Luz; P. R. Mahaffy; U. Mall; J. Martinez-Frias; B. Marty; T. McCord; C. Menor Salvan; A. Milillo; D. G. Mitchell; R. Modolo; O. Mousis; M. Nakamura; C. D. Neish; C. A. Nixon; D. Nna Mvondo; G. Orton; M. Paetzold; J. Pitman; S. Pogrebenko; W. Pollard; O. Prieto-Ballesteros; P. Rannou; K. Reh; L. Richter; F. T. Robb; R. Rodrigo; S. Rodriguez; P. Romani; M. Ruiz Bermejo; E. T. Sarris; P. Schenk; B. Schmitt; N. Schmitz; D. Schulze-Makuch; K. Schwingenschuh; A. Selig; B. Sicardy; L. Soderblom; L. J. Spilker; D. Stam; A. Steele; K. Stephan; D. F. Strobel; K. Szego; C. Szopa; R. Thissen; M. G. Tomasko; D. Toublanc; H. Vali; I. Vardavas; V. Vuitton; R. A. West; R. Yelle; E. F. Young

2009-01-01

134

TandEM: Titan and Enceladus mission  

USGS Publications Warehouse

TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfi??re) and possibly several landing probes to be delivered through the atmosphere. ?? Springer Science + Business Media B.V. 2008.

Coustenis, A.; Atreya, S. K.; Balint, T.; Brown, R. H.; Dougherty, M. K.; Ferri, F.; Fulchignoni, M.; Gautier, D.; Gowen, R. A.; Griffith, C. A.; Gurvits, L. I.; Jaumann, R.; Langevin, Y.; Leese, M. R.; Lunine, J. I.; McKay, C. P.; Moussas, X.; Muller-Wodarg, I.; Neubauer, F.; Owen, T. C.; Raulin, F.; Sittler, E. C.; Sohl, F.; Sotin, C.; Tobie, G.; Tokano, T.; Turtle, E. P.; Wahlund, J. -E.; Waite, J. H.; Baines, K. H.; Blamont, J.; Coates, A. J.; Dandouras, I.; Krimigis, T.; Lellouch, E.; Lorenz, R. D.; Morse, A.; Porco, C. C.; Hirtzig, M.; Saur, J.; Spilker, T.; Zarnecki, J. C.; Choi, E.; Achilleos, N.; Amils, R.; Annan, P.; Atkinson, D. H.; Benilan, Y.; Bertucci, C.; Bezard, B.; Bjoraker, G. L.; Blanc, M.; Boireau, L.; Bouman, J.; Cabane, M.; Capria, M. T.; Chassefiere, E.; Coll, P.; Combes, M.; Cooper, J. F.; Coradini, A.; Crary, F.; Cravens, T.; Daglis, I. A.; de Angelis, E.; de Bergh, C.; de Pater, I.; Dunford, C.; Durry, G.; Dutuit, O.; Fairbrother, D.; Flasar, F. M.; Fortes, A. D.; Frampton, R.; Fujimoto, M.; Galand, M.; Grasset, O.; Grott, M.; Haltigin, T.; Herique, A.; Hersant, F.; Hussmann, H.; Ip, W.; Johnson, R.; Kallio, E.; Kempf, S.; Knapmeyer, M.; Kofman, W.; Koop, R.; Kostiuk, T.; Krupp, N.; Kuppers, M.; Lammer, H.; Lara, L. -M.; Lavvas, P.; Le, Mouelic, S.; Lebonnois, S.; Ledvina, S.; Li, J.; Livengood, T. A.; Lopes, R. M.; Lopez-Moreno, J. -J.; Luz, D.; Mahaffy, P. R.; Mall, U.; Martinez-Frias, J.; Marty, B.; McCord, T.; Salvan, C. M.; Milillo, A.; Mitchell, D. G.; Modolo, R.; Mousis, O.; Nakamura, M.; Neish, C. D.; Nixon, C. A.; Mvondo, D. N.; Orton, G.; Paetzold, M.; Pitman, J.; Pogrebenko, S.; Pollard, W.; Prieto-Ballesteros, O.; Rannou, P.; Reh, K.; Richter, L.; Robb, F. T.; Rodrigo, R.; Rodriguez, S.; Romani, P.; Bermejo, M. R.; Sarris, E. T.; Schenk, P.; Schmitt, B.; Schmitz, N.; Schulze-Makuch, D.; Schwingenschuh, K.; Selig, A.; Sicardy, B.; Soderblom, L.; Spilker, L. J.; Stam, D.; Steele, A.; Stephan, K.; Strobel, D. F.; Szego, K.; Szopa,

2009-01-01

135

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

136

Unusual enhancer function in yeast rRNA transcription.  

PubMed Central

The rRNA genes in most eucaryotic organisms are present in a tandem array. There is substantial evidence that transcription of one of these genes may not be independent of transcription of others. In particular, in the yeast Saccharomyces cerevisiae, the enhancer of rRNA transcription that lies 2.2 kilobases 5' of the transcription initiation site is at least partly within the upstream transcription unit. To ask more directly about the relationship of the tandemness of these genes to their transcription, we have constructed a minirepeat containing two identifiable test genes, with or without enhancer(s). On integration into the URA3 locus, these genes were transcribed by RNA polymerase I. A single enhancer effectively stimulated transcription of both genes by 10- to 30-fold, even when it was located upstream of both or downstream of both. Two enhancers had roughly additive effects. These results suggest a model of enhancer function in tandemly repeated genes. Images

Johnson, S P; Warner, J R

1989-01-01

137

Form-focused Interaction in Online Tandem Learning  

Microsoft Academic Search

Tandem language learning—a configuration involving pairs of learners with complementary target\\/native languages—is an underexploited but potentially very powerful use of computer-mediated communication (CMC) in second-lan- guage pedagogy. Tandem offers the benefits of authentic, culturally grounded interaction, while also promoting a pedagogical focus among participants. CMC- based tandem promises, in addition, those benefits believed to accrue from text- based interaction, in

Breffni O'Rourke

2005-01-01

138

Tandem robot control system and method for controlling mobile robots in tandem  

DOEpatents

A control system for controlling mobile robots provides a way to control mobile robots, connected in tandem with coupling devices, to navigate across difficult terrain or in closed spaces. The mobile robots can be controlled cooperatively as a coupled system in linked mode or controlled individually as separate robots.

Hayward, David R. (Albuquerque, NM); Buttz, James H. (Albuquerque, NM); Shirey, David L. (Albuquerque, NM)

2002-01-01

139

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

140

Plasma confinement in the TMX tandem mirror  

SciTech Connect

Plasma confinement in the Tandem Mirror Experiment (TMX) is described. Axially confining potentials are shown to exist throughout the central 20-cm core of TMX. Axial electron-confinement time is up to 100 times that of single-cell mirror machines. Radial transport of ions is smaller than axial transport near the axis. It has two parts at large radii: nonambipolar, in rough agreement with predictions from resonant-neoclassical transport theory, and ambipolar, observed near the plasma edge under certain conditions, accompanied by a low-frequency, m = 1 instability or strong turbulence.

Hooper, E.B. Jr.; Allen, S.L.; Casper, T.A.

1981-04-29

141

Tandem-mirror technology demonstration facility  

NASA Astrophysics Data System (ADS)

Preliminary calculations for a technology demonstration facility consisting of a tandem mirror machine are reported. This machine produces 12 MW of DT neutrons in steady state from a plasma column 0.08 m in radius and 8 m in length. Allowing space for neutral beam injectors at each end of the column, this permits testing of blanket modules and components at 1 MW/sq m neutron wall load over a cylindrical surface 8 sq m in area at a radius o 0.25 m; or irradiation of thousands of small samples at 2 MW/sq m at r = 0.125 m (4 sq m area).

Fowler, T. K.; Logan, B. G.

1981-09-01

142

The Naples University 3 MV tandem accelerator  

SciTech Connect

The 3 MV tandem accelerator of the Naples University is used for research activities and applications in many fields. At the beginning of operation (1977) the main utilization was in the field of nuclear physics. Later, the realization of new beam lines allowed the development of applied activities as radiocarbon dating, ion beam analysis, biophysics, ion implantation etc. At present, the availability of different ion sources and many improvements on the accelerator allow to run experiments in a wide range of subjects. An overview of the characteristics and major activities of the laboratory is presented.

Campajola, L.; Brondi, A. [Dipartimento di Scienze Fisiche, Universita di Napoli ''Federico II'' Complesso Universitario di Monte S.Angelo via Cintia 80126 Napoli, Italy and Istituto Nazionale di Fisica Nucleare, Sez. di Napoli (Italy)

2013-07-18

143

Some new ideas for Tandem Mirror blankets  

SciTech Connect

The Tandem Mirror Reactor, with its cylindrical central cell, has led to numerous blanket designs taking advantage of the simple geometry. Also many new applications for fusion neutrons are now being considered. To the pure fusion electricity producers and hybrids producing fissile fuel, we are adding studies of synthetic fuel producers and fission-suppressed hybrids. The three blanket concepts presented are new ideas and should be considered illustrative of the breadth of Livermore's application studies. They are not meant to imply fully analyzed designs.

Neef, W.S. Jr.

1981-10-12

144

Linearbeschleuniger und Tandem-van-de-Graaffs: Werkzeuge der Schwerionenforschung  

NASA Astrophysics Data System (ADS)

The basic principles of dc-tandem and high-frequency linear accelerator are discussed by referring to the pioneering work of H. Kallmann and R. Wideröe. The 30 MV Supertandem in Daresbury, the Heidelberg combination of tandem and linac, and the universal linear accelerator Unilac of the GSI at Darmstadt serve as examples of modern heavy-ion accelerators.

Brix, P.; Ingwersen, H.; Jaeschke, E.; Repnow, R.

1980-06-01

145

Experimental Protein Mixture for Validating Tandem Mass Spectral Analysis  

Microsoft Academic Search

Several methods have been used to identify peptides that correspond to tandem mass spec- tra. In this work, we describe a data set of low energy tandem mass spectra generated from a control mixture of known protein components that can be used to evaluate the accuracy of these methods. As an example, these spectra were searched by the SEQUEST application

Andrew Keller; Samuel Purvine; Alexey I. Nesvizhskii; Sergey Stolyar; David R. Goodlett; Eugene Kolker

2002-01-01

146

13C Isotopomer Analysis of Glutamate by Tandem Mass Spectrometry  

Microsoft Academic Search

Tandem mass spectrometry allows a compound to be isolated from the rest of the sample and dissociated into smaller fragments. We show here that fragmentation of glutamate mass isotopomers yields additional mass spectral data that significantly improve the analysis of metabolic fluxes compared to full-scan mass spectrometry. In order to validate the technique, tandem and full-scan mass spectrometry were used

F. Mark H. Jeffrey; J. Shawn Roach; Charles J. Storey; A. Dean Sherry; Craig R. Malloy

2002-01-01

147

Development of an advanced spacecraft tandem mass spectrometer  

Microsoft Academic Search

The purpose of this research was to apply current advanced technology in electronics and materials to the development of a miniaturized Tandem Mass Spectrometer that would have the potential for future development into a package suitable for spacecraft use. The mass spectrometer to be used as a basis for the tandem instrument would be a magnetic sector instrument, of Nier-Johnson

Russell C. Drew

1992-01-01

148

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

149

Form-Focused Interaction in Online Tandem Learning  

ERIC Educational Resources Information Center

Tandem language learning--a configuration involving pairs of learners with complementary target/native languages--is an underexploited but potentially very powerful use of computer-mediated communication (CMC) in second-language pedagogy. Tandem offers the benefits of authentic, culturally grounded interaction, while also promoting a pedagogical…

O'Rourke, Breffni

2005-01-01

150

Speckle-phase measurement in a tandem-vortex coronagraph.  

PubMed

A tandem-vortex coronagraph can in theory enable high-contrast imaging behind a classical on-axis telescope. Here we point out that a tandem-vortex coronagraph configuration can also directly enable the measurement of the phases of focal-plane speckles, thereby allowing for their suppression in the resultant high-contrast image. PMID:22016212

Serabyn, Eugene; Wallace, J Kent; Mawet, Dimitri

2011-10-01

151

A set-up model for tandem cold rolling mills  

Microsoft Academic Search

It is well known that experience is playing a vital role in the selection of operating parameters in tandem cold rolling mills. In the present work, an attempt is made to develop a set-up model for tandem cold rolling mill to maximize the throughput. In the present work, power consumed is calculated and compared for various reduction schedules obtained by

N. Venkata Reddy; G. Suryanarayana

2001-01-01

152

Tandem Mirror and Field-Reversed Mirror Experiments.  

National Technical Information Service (NTIS)

This paper is largely devoted to tandem mirror and field-reversed mirror experiments at the Lawrence Livermore Laboratory (LLL), and briefly summarizes results of experiments in which field-reversal has been achieved. In the tandem experiment, high-energy...

F. H. Coensgen T. C. Simonen W. C. Turner

1979-01-01

153

Progress in the tandem mirror program  

SciTech Connect

Experimental results in TMX have confirmed the basic principles of the tandem-mirror concept. A center-cell particle confinement parameter eta tau approx. 10/sup 11/ cm/sup -3/ s has been obtained at ion temperatures around 100 eV, which is a hundred-fold improvement over single mirrors at the same temperatures. For TMX these results have been obtained at peak beta values in the center cell in the range 10 to 40%, not yet limited by MHD activity; and ion-cyclotron resonant heating (ICRH) in the Phaedrus tandem-mirror experiment has produced beta values approx. 25%, which is several times the ideal MHD limit for that device. In addition, it has been demonstrated that the end fan chambers of TMX simultaneously isolate the hot electrons from the end walls, provide adequate pumping and conveniently dispose of the exhaust plasma energy either by thermal deposition on the end wall or by direct conversion to electricity (at 48% efficiency in agreement with calculations). Also, evidence was obtained for inherent divertor action in TMX, presumably in part responsible for the observed low impurity level (<0.5% low-Z ions in the center cell).

Fowler, T.K.; Borchers, R.R.

1981-09-13

154

The Bucharest FN Tandem Accelerator: Modernization and Development  

NASA Astrophysics Data System (ADS)

The Bucharest FN tandem accelerator, installed in 1973 and upgraded in 1983 to 9 MV, has been used for atomic and nuclear physics studies as well as for different applications using accelerated ion beams. In the last three years a program of modernization of the tandem accelerator including the replacement of the old accelerator equipment by new ones, installation of a pelletron system for the Van de Graaff generator and installation of new negative ion injectors was undertaken. In parallel a development of the tandem accelerator was started. In 2009, a beam pulsing system in the nanosecond range is scheduled to be installed. All these works aimed to transform the tandem accelerator in a reliable and efficient tool for research and applications are presented. The main lines of the research program at the Bucharest tandem accelerator are shortly presented too.

Dobrescu, S.; Mosu, D. V.; Moisa, D.; Papureanu, S.

2009-03-01

155

Tandem Time-of-Flight (TOF/TOF) Mass Spectrometry and Proteomics.  

PubMed

A dual reflectron tandem time-of-flight (TOF/TOF) mass spectrometer reported in 1993 gave rise to the invention and development of the curved-field reflectron (CFR) for focusing product ions. The CFR is used in this case as the second mass analyzer in a tandem instrument (based on the Kratos AXIMA CFR) in which the first mass analyzer is a linear TOF that focuses ions by pulsed extraction. Because ions can be focused over a broad range of kinetic energies, deceleration of precursor ions and/or reacceleration of product ions is not required. Thus, product ions produced by post-source processes (laser induced dissociation or LID, metastable decomposition and opportunistic collisions) are recorded in the product ion mass spectra at the same times as their isomass ions produced by collision induced dissociation (CID). In general both LID and CID product ion mass spectra are very similar, producing primarily b-series and y-series ions, though there is some preference for fragmentation at weaker bonds such as those at proline or aspartic acid residues. The tandem mass spectrometer has been used to determine the acetylation sites for a histone acetyl transferase (HAT) protein. A novel and improved method for derivatizing tryptic fragments by N-terminal sulfonation produces almost exclusively y-series ions, and has been used to determine protein ubiquitination. The tandem mass spectrometer has also been used to identify potential biomarkers associated with heart failure, in particular that fraction containing albumin that is generally removed from serum samples to permit protein biomarker analysis. Analysis of the unfractionated serum, the albuminome, and the depleted serum is also carried out using surface-enhanced laser desorption/ionization (SELDI) and the high molecular weight proteins are monitored by using a Comet macromizer TOF mass spectrometer with a very high mass cryocooled detector. PMID:20717501

Cotter, Robert J; Iltchenko, Serguei; Wang, Dongxia; Gundry, Rebekah

2005-01-01

156

Cerivastatin enhances the cytotoxicity of 5-fluorouracil on chemosensitive and resistant colorectal cancer cell lines.  

PubMed

Cerivastatin is one of the synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors used for the treatment and prevention of hypercholesterolaemia. The observation that patients receiving this drug had a lower incidence at cancer led to our interest in using it as a putative anticancer agent. In this study, we tested the cytotoxicity of cerivastatin on a panel of 5-fluorouracil (5FU) sensitive and resistant cell lines in vitro. Cerivastatin was cytotoxic to both 5FU sensitive and resistant cells. Cerivastatin significantly augmented the cytotoxic effect of 5FU on drug sensitive (6-22-fold) and resistant (229-310-fold) cell lines. Cerivastatin and 5FU acted synergistically. Cerivastatin inhibited nuclear factor kappaB DNA binding activity. The enhancing effect of cerivastatin on 5FU was partially mevalonate pathway independent. Cerivastatin may allow successful 5FU therapy in chemoresistant patients. PMID:12435585

Wang, Weiguang; Collie-Duguid, Elaina; Cassidy, James

2002-11-20

157

Poiseuille flow-induced vibrations of two cylinders in tandem  

NASA Astrophysics Data System (ADS)

Laminar flows past two tandem cylinders which are free to move transversely in a parallel-wall channel were studied numerically by the lattice Boltzmann method. With fixed Reynolds number Re=100, blockage ratio ?=1/4 and structural damping ?=0, the effect of streamwise separation between two cylinders at a range of S/D=[1.1, 10] on the motions of cylinders and fluids was studied for both mass ratios of m(*)=1 and m(*)=0.1. A variety of distinct vibration regimes involving periodic, quasi-periodic and non-periodic vibrations with corresponding flow patterns were observed. A detailed analysis of the vibration amplitudes, vibration frequencies and relative equilibrium positions for both mass ratios demonstrated that as S/D increases, the interaction of the two cylinders first enhances and then reduces. In the strong coupling regime, both cylinders oscillate periodically around the centerline of the channel with large vibration amplitudes and high vibration frequencies. By comparing with the case of an isolated cylinder, a further study indicated that the gap flow plays an important role in such a dynamic system, and the vortex cores formation behind the front cylinder causes the interaction of the cylinders decouple rapidly. Based on the present observations, such a dynamic model system can be considered as a novel type of vortex-induced vibrations (VIV) and is expected to find applications in fluid mixing and heat transfer.

Lin, Jianzhong; Jiang, Renjie; Chen, Zhongli; Ku, Xiaoke

2013-07-01

158

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

159

A new tandem mass spectrometer for photofragment spectroscopy of cold, gas-phase molecular ions  

SciTech Connect

We present here the design of a new tandem mass spectrometer that combines an electrospray ion source with a cryogenically cooled ion trap for spectroscopic studies of cold, gas-phase ions. The ability to generate large ions in the gas phase without fragmentation, cool them to {approx}10 K in an ion trap, and perform photofragment spectroscopy opens up new possibilities for spectroscopic characterization of large biomolecular ions. The incorporation of an ion funnel, together with a number of small enhancements, significantly improves the sensitivity, signal stability, and ease of use compared with the previous instrument built in our laboratory.

Svendsen, Annette; Lorenz, Ulrich J.; Boyarkin, Oleg V.; Rizzo, Thomas R. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne (Switzerland)

2010-07-15

160

Initial results of the Tandem Mirror Experiment (TMX) at the Lawrence Livermore Laboratory  

SciTech Connect

Initial experimental results from the Tandem Mirror Experiment (TMX) are presented. Axial profiles of the plasma density and potential necessary for electrostatically enhanced confinement of the central-cell ions have been generated and sustained for the duration of neutral-beam injection. The resulting central-cell ion confinement against axial loss is improved by a factor as large as 9 above that given by magnetic confinement alone. The plasma exhibits gross magnetohydrodynamic stability and microstability. Under some conditions, a residual level of ion cyclotron fluctuations in the end cells heats the central-cell ions and degrades their confinement.

Grubb, D.P.; Anderson, C.A.; Casper, T.A.; Clauser, J.F.; Coensgen, F.H.; Correll, D.L.; Cummins, W.F.; Davis, J.C.; Drake, R.P.; Foote, J.H.

1980-04-02

161

Enhancement of light absorption efficiency of amorphous-silicon thin-film tandem solar cell due to multiple surface-plasmon-polariton waves in the near-infrared spectral regime*  

NASA Astrophysics Data System (ADS)

The reflectances of a thin-film solar cell were computed, using the rigorous coupled-wave approach, as functions of the angle of incidence and the free-space wavelength for illumination by linearly polarized plane waves. A tandem solar cell made of amorphous-silicon alloys was considered. The metallic back-reflector was taken to be periodically corrugated. Both the simple and the compound periodic corrugations of the metallic back-reflector (surface-relief gratings) were investigated. Low-reflectance bands in the reflectance spectrums were correlated with the solutions of the underlying canonical boundary-value problem to delineate the excitation of multiple surface-plasmon-polariton (SPP) waves. For the standard AM1.5 solar irradiance spectrum, we found that the light absorption efficiency in the near-infrared spectral regime can be increased up to 100% when multiple SPP waves of both linear polarization states are excited.

Faryad, Muhammad; Lakhtakia, Akhlesh

2013-08-01

162

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

163

Tandem mass spectrometry of low solubility polyamides.  

PubMed

The structural characterization of polyamides (PA) was achieved by tandem mass spectrometry (MS/MS) with a laser induced dissociation (LID) strategy. Because of interferences for precursor ions selection, two chemical modifications of the polymer end groups were proposed as derivatization strategies. The first approach, based on the addition of a trifluoroacetic acid (TFA) molecule, yields principally to complementary bn and yn product ions. This fragmentation types, analogous to those obtained with peptides or other PA, give only poor characterization of polymer end-groups [1]. A second approach, based on the addition of a basic diethylamine (DEA), permits to fix the charge and favorably direct the fragmentation. In this case, bn ions were not observed. The full characterization of ? end group structure was obtained, in addition to the expected yn and consecutive fragment ions. PMID:24370089

Barrère, Caroline; Hubert-Roux, Marie; Afonso, Carlos; Rejaibi, Majed; Kebir, Nasreddine; Désilles, Nicolas; Lecamp, Laurence; Burel, Fabrice; Loutelier-Bourhis, Corinne

2014-01-15

164

Parametric systems analysis for tandem mirror hybrids  

SciTech Connect

Fusion fission systems, consisting of fissile producing fusion hybrids combining a tandem mirror fusion driver with various blanket types and net fissile consuming LWR's, have been modeled and analyzed parametrically. Analysis to date indicates that hybrids can be competitive with mined uranium when U/sub 3/O/sub 8/ cost is about 100 $/lb., adding less than 25% to present day cost of power from LWR's. Of the three blanket types considered, uranium fast fission (UFF), thorium fast fission (ThFF), and thorium fission supressed (ThFS), the ThFS blanket has a modest economic advantage under most conditions but has higher support ratios and potential safety advantages under all conditions.

Lee, J.D.; Chapin, D.L.; Chi, J.W.H.

1980-09-01

165

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

166

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

167

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

168

Analysis of the largest tandemly repeated DNA families in the human genome  

Microsoft Academic Search

BACKGROUND: Tandemly Repeated DNA represents a large portion of the human genome, and accounts for a significant amount of copy number variation. Here we present a genome wide analysis of the largest tandem repeats found in the human genome sequence. RESULTS: Using Tandem Repeats Finder (TRF), tandem repeat arrays greater than 10 kb in total size were identified, and classified

Peter E Warburton; Dan Hasson; Flavia Guillem; Chloe Lescale; Xiaoping Jin; Gyorgy Abrusan

2008-01-01

169

Protein identification from tandem mass spectra by database searching.  

PubMed

Protein identification from tandem mass spectra is one of the most versatile and widely used proteomics workflows, able to identify proteins, characterize post-translational modifications, and provide semi-quantitative measurements of relative protein abundance. This manuscript describes the concepts, prerequisites, and methods required to analyze a tandem mass spectrometry dataset in order to identify its proteins, by using a tandem mass spectrometry search engine to search protein sequence databases. The discussion includes instructions for extraction, preparation, and formatting of spectral datafiles; selection of appropriate search parameter settings; and basic interpretation of the results. PMID:21082432

Edwards, Nathan J

2011-01-01

170

A tandem-based compact dual-energy gamma generator  

NASA Astrophysics Data System (ADS)

A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.

Persaud, A.; Kwan, J. W.; Leitner, M.; Leung, K.-N.; Ludewigt, B.; Tanaka, N.; Waldron, W.; Wilde, S.; Antolak, A. J.; Morse, D. H.; Raber, T.

2010-02-01

171

Tandem warhead considerations for electronic safety and arming devices.  

National Technical Information Service (NTIS)

There are four issues that an ESA designer must address when designing a tandem system: (1) warhead detonation shock, (2) warhead detonation ion cloud, (3) warhead detonation electromagnetic pulse, and (4) slapper/sparkgap electromagnetic pulse. Each of t...

D. Dell A. Medina

1990-01-01

172

5. GENERAL VIEW OF UNITEDTOD TWIN TANDEM STEAM ENGINE. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. GENERAL VIEW OF UNITED-TOD TWIN TANDEM STEAM ENGINE. - Republic Iron & Steel Company, Youngstown Works, Blooming Mill & Blooming Mill Engines, North of Poland Avenue, Youngstown, Mahoning County, OH

173

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions  

PubMed Central

Summary The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding ?-hydroxyketones.

Jeena, Vineet

2009-01-01

174

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

175

Plasma-wall interactions in tandem mirror machines  

SciTech Connect

A description is presented of the plasma-surface interactions in thermal-barrier tandem-mirror machines. The thermal-barrier mode of axial confinement is an integral part of a tandem mirror, and it dictates the required plasma conditions, particularly at the surface of the plasma. For this reason, a qualitative discussion of the thermal barrier is presented first in Section 2. A brief description of the experimental configuration used in tandem mirrors to create the thermal barrier is then examined in detail in Section 3; the TMX-U and MFTF-B machines are used as specific examples. In Section 4, the relevant plasma-surface interaction issues are addressed, and experimental results from currently operating tandom mirror machines are included. Section 5 is both a summary and a discussion of future work concerned with plasma-surface interactions in tandem mirrors.

Allen, S.L.

1984-11-01

176

Tandem wheel drop-legs for standard truck trailer  

NASA Technical Reports Server (NTRS)

Tandem wheel drop-leg device provides a semitrailer with fore and aft mobility that allows it to be moved without a prime mover. The modified drop-legs have trunnion dual wheels and an adjustable brace.

Cantwell, W.; Selstad, R.

1970-01-01

177

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

178

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

179

Thiopurine methyltransferase polymorphic tandem repeat: Genotype-phenotype correlation analysis  

Microsoft Academic Search

Background: Thiopurine methyltransferase (TPMT) is a genetically polymorphic enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine. Recently, a variable number tandem repeat (VNTR) within the TPMT promoter has been reported to “modulate” levels of this enzyme activity.Methods: We set out to perform genotype-phenotype correlation analysis for the polymorphic TPMT tandem repeat in 1211 clinical laboratory samples in

Lan Yan; Shuichen Zhang; Bianca Eiff; Carol L. Szumlanski; Melody Powers; John F. O'Brien; Richard M. Weinshilboum

2000-01-01

180

NTRFinder: a software tool to find nested tandem repeats  

PubMed Central

We introduce the software tool NTRFinder to search for a complex repetitive structure in DNA we call a nested tandem repeat (NTR). An NTR is a recurrence of two or more distinct tandem motifs interspersed with each other. We propose that NTRs can be used as phylogenetic and population markers. We have tested our algorithm on both real and simulated data, and present some real NTRs of interest. NTRFinder can be downloaded from http://www.maths.otago.ac.nz/~aamatroud/.

Matroud, Atheer A.; Hendy, M. D.; Tuffley, C. P.

2012-01-01

181

Design of Tandem Architecture Using Segmental Trend Features  

Microsoft Academic Search

This paper investigates the tandem architecture (TA) based on segmental features. The segmental feature based recognition\\u000a system has been reported to show better results than the conventional feature based system in previous studies. In this paper\\u000a we tried to merge the segmental feature with the tandem architecture which uses both hidden Markov models and neural networks.\\u000a In general, segmental features

Young-sun Yun; Yunkeun Lee

2007-01-01

182

Global design optimization for an axial-flow tandem pump based on surrogate method  

NASA Astrophysics Data System (ADS)

Tandem pump, compared with multistage pump, goes without guide vanes between impellers. Better cavitation performance and significant reduction of the axial geometry scale is important for high-speed propulsion. This study presents a global design optimization method based on surrogated method for an axial-flow tandem pump to enhance trade-off performances: energy and cavitation performances. At the same time, interactions between impellers and impacts on the performances are analyzed. Fixed angle of blades in impellers and phase angle are performed as design variables. Efficiency and minimum average pressure coefficient (MAPC) on axial sectional surface in front impeller are the objective function, which can represent energy and cavitation performances well. Different surrogate models are constructed, and Global Sensitivity Analysis and Pareto Front method are used. The results show that, 1) Influence from phase angle on performances can be neglected compared with other two design variables, 2) Impact ratio of fixed angle of blades in two impellers on efficiency are the same as their designed loading distributions, which is 4:6, 3) The optimization results can enhance the trade-off performances well: efficiency is improved by 0.6%, and the MAPC is improved by 4.5%.

Li, D. H.; Zhao, Y.; Y Wang, G.

2013-12-01

183

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

184

Analysis of acrylamide in different foodstuffs using liquid chromatography–tandem mass spectrometry and gas chromatography–tandem mass spectrometry  

Microsoft Academic Search

Acrylamide levels over a wide range of different food products were analysed using both liquid chromatography–tandem mass spectrometry (HPLC–MS–MS) and gas chromatography–tandem mass spectrometry (GC–MS–MS). Two different sample preparation methods for HPLC–MS–MS analysis were developed and optimised with respect to a high sample throughput on the one hand, and a robust and reliable analysis of difficult matrices on the other

K. Hoenicke; R. Gatermann; W. Harder; L. Hartig

2004-01-01

185

How tandem power motors improve drilling performance  

SciTech Connect

Tandem power section positive displacement mud-motors (TPS-PDMs) can increase penetration rate when used with tricone and PDC bits. This is achieved by increasing the available output torque and shaft rotational speed by reducing pressure drop per stage in the power section. Early PDMs were single-lobe 1:2 rotor-stator ratio motors. Horsepower produced by these PDMs was a result of high output-shaft rotational speeds and low output torque. Most later PDMs have rotor-stator ratios ranging from 3:4 to 10:11. This change to a higher ratio increased output torque, but also caused a decrease in rotational output-shaft speed. Motor power, a product of torque and speed, has not changed significantly in any particular motor size since the early PDMs. Modern day PDC and tricone ''motor'' bit use requires that PDMs provide high torque and medium to high (180- to 300-rpm) output shaft speeds. This paper discusses the four primary variables in the basic design of any PDM power section for a given diameter tool. Variables are: rotor-stator lobe ratio; lobe spiral pitch; maximum design pressure drop; and number of stages.

Califf, B.; Johnson, M. (Drilex Systems, Inc., Houston, TX (United States))

1994-10-01

186

Electrospray tandem mass spectrometry of epipolythiodioxopiperazines.  

PubMed

Low-energy collision-induced electrospray ionization tandem mass spectrometry ESI-CID-MS/MS (in the positive ion mode) was used for the structural characterization of a series of five representative epioplythiodioxopipreazines: dethiotetra(methylthio)chemotin, chaetocochins A, B and C, and chemotin isolated from the fungus Chaetomium cochliodes. The fragmentation pathways were elucidated by ESI-IT-MS(n). The elemental compositions of most of the product ions were confirmed by low-energy ESI-CID-QTOF-MS/MS analyses. The loss of the S(2) molecule seems always to be the first when the S--S bond is present. The loss of 77 Da corresponding to the loss of the [CH(3)SCH(2)O]' radical was diagnostic for chaetocochins A and B, in which the two piperazines rings are linked by an acetal group. It was found that a McLafferty rearrangement plays a significant role in the skeleton fragmentation of theses series of studied complex multicyclic piperazine compounds. This MacLafferty rearrangement affords the product ions at m/z 416 and 400, containing the two piperazine rings belonging to the epipolythiodioxopipreazines. In addition, the pentacyclic rearrangement involving the loss of the SMe(.) radical seems to occur in the presence of the unfused ring. Finally the product ions at m/z 635 and 591 seem to be the characteristic ions for chaetocochin A. PMID:17492721

Wu, Zhi-Jun; Li, Guo-You; Fang, Dong-Mei; Qi, Hua-Yi; Ren, Wei-Jian; Zhang, Guo-Lin

2007-06-01

187

Analysis of tandem mirror reactor performance  

SciTech Connect

Parametric studies are performed using a tandem mirror plasma point model to evaluate the wall loading GAMMA and the physics figure of merit, Q (fusion power/injected power). We explore the relationship among several dominant parameters and determine the impact on the plasma performance of electron cyclotron resonance heating in the plug region. These global particle and energy balance studies were carried out under the constraints of magnetohydrodynamic (MHD) equilibrium and stability and constant magnetic flux, assuming a fixed end-cell geometry. We found that the higher the choke coil fields, the higher the Q, wall loading, and fusion power due to the combination of the increased central-cell field B/sub c/ and density n/sub c/ and the reduced central-cell beta ..beta../sub c/. The MHD stability requirement of constant B/sub c//sup 2/..beta../sub c/ causes the reduction in ..beta../sub c/. In addition, a higher value of fusion power can also be obtained, at a fixed central-cell length, by operating at a lower value of B/sub c/ and a higher value of ..beta../sub c/.

Wu, K.F.; Campbell, R.B.; Peng, Y.K.M.

1984-11-01

188

Differential chromatin structure within a tandem array 100 kb upstream of the maize b1 locus is associated with paramutation  

PubMed Central

Recombination mapping defined a 6-kb region, 100 kb upstream of the transcription start site, that is required for B-I enhancer activity and paramutation—a stable, heritable change in transcription caused by allele interactions in maize (Zea mays). In this region, B-I and B‘ (the only b1 alleles that participate in paramutation) have seven tandem repeats of an 853-bp sequence otherwise unique in the genome; other alleles have one. Examination of recombinant alleles with different numbers of tandem repeats indicates that the repeats are required for both paramutation and enhancer function. The 6-kb region is identical in B-I and B‘, showing that epigenetic mechanisms mediate the stable silencing associated with paramutation. This is the first endogenous gene for which sequences required for paramutation have been defined and examined for methylation and chromatin structure. The tandem repeat sequences are more methylated in B-I (high expressing) relative to B‘ (low expressing), opposite of the typical correlation. Furthermore, the change in repeat methylation follows establishment of the B‘ epigenetic state. B-I has a more open chromatin structure in the repeats relative to B‘. The nuclease hypersensitivity differences developmentally precede transcription, suggesting that the repeat chromatin structure could be the heritable imprint distinguishing the two transcription states.

Stam, Maike; Belele, Christiane; Dorweiler, Jane E.; Chandler, Vicki L.

2002-01-01

189

Transcription of the tandem array of ribosomal DNA in Drosophila melanogaster does not terminate at any fixed point  

PubMed Central

Transcription termination of the polymerase I transcribed rRNA genes is thought to occur at or closely behind the end of the 28S gene coding region. We show here that this is not the case for Drosophila melanogaster. Nuclease S1 mapping of total RNA and a nuclear `run-on' assay reveal that there is no defined point of termination throughout the whole spacer separating the two genes. Since the rRNA genes in D. melanogaster are organized in tandem arrays, this implies that readthrough transcription of one unit can occur up to, and possibly through, the promoter of the next unit. Readthrough transcription might be a component of transcription enhancement in a tandem array of genes. ImagesFig. 2.Fig. 3.Fig. 4.

Tautz, Diethard; Dover, Gabriel A.

1986-01-01

190

Tax Protein of Human T-Cell Leukemia Virus Type I Binds to the Ankyrin Motifs of Inhibitory Factor kappaB and Induces Nuclear Translocation of Transcription Factor NF-kappaB Proteins for Transcriptional Activation  

Microsoft Academic Search

Human T-cell leukemia virus type I causes adult T-cell leukemia and tropical spastic paraparesis, and its regulator protein Tax has been implicated in the pathogenic activity of human T-cell leukemia virus type I. Tax activates transcription of viral and cellular genes through specific enhancers: the 21-bp enhancer of human T-cell leukemia virus type I, the nuclear factor kappa B (NF-kappa

Hiroshi Hirai; Takeshi Suzuki; Jun-Ichi Fujisawa; Jun-Ichiro Inoue; Mitsuaki Yoshida

1994-01-01

191

Flow past tandem cylinders under forced vibration  

NASA Astrophysics Data System (ADS)

Flow past two cylinders in tandem arrangement under forced vibration has been studied experimentally employing the hydrogen bubble visualization technique. The Reynolds number, based on the cylinder diameter, is fixed at Re=250. In stationary state of the two cylinders with P/D=2.0, dual vortex shedding frequencies fL (St=0.14) and fH (St=0.18) are identified. fL is associated with the shear layer reattachment behavior and fH is related to the single bluff body behavior. Under a variety of forced vibrations of the two cylinders at a fixed vibration amplitude A/D=0.25, diverse and highly-repetitive vortex patterns are yielded. They are classified into two typical modes—a low-frequency mode and a high-frequency mode. The two modes are represented by two vortex patterns yielded from in-phase vibration of the two cylinders with P/D=2.0 and at vibration frequencies fe?fL and fe?fH. The difference between the two modes is on the number of vortices formed per vibration cycle. For the low-frequency mode, the number is four; for the high-frequency model, it is two. In both modes, the vortex formation is phase-locked to the cylinder motion. For a specified mode with a fixed vortex number per cycle, the way the vortices evolve in the wake can be somewhat different by changing the vibration frequency, pitch ratio, as well as the vibration type. These affecting factors have been examined in this work, and the associated vortex patterns have been characterized and compared.

Yang, Yingchen; Aydin, Tayfun B.; Ekmekci, Alis

2014-01-01

192

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

193

Design of a new tandem wings hybrid airship  

NASA Astrophysics Data System (ADS)

It is scientifically important science value and engineering promising to develop the buoyancy-lift integrated hybrid airship for high attitude platform. Through the numerical method, a new tandem wings hybrid airship with both higher utility value and economy efficiency was obtained and its total performance and technical parameters were analyzed in detail. In order to further improve the lift-drag characteristics, we implemented the optimization design for aerodynamic configuration of tandem wings hybrid airship via the response surface method. The results indicate that the tandem wings hybrid airship has considerable volume efficiency and higher aerodynamic characteristics. After optimization, the lift-drag ratio of this hybrid airship was increased by 6.08%. In a given gross lift condition, tandem wings hybrid airship may provide more payload and specific productivity. Furthermore, the size of tandem airship is smaller so the demand for skin flexible materials can be reduced. Results of this study could serve as a new approach to designing buoyancy-lifting integrated hybrid airship.

Li, Feng; Ye, ZhengYin; Gao, Chao

2012-10-01

194

Dynamic landscape of tandem 3' UTRs during zebrafish development.  

PubMed

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. PMID:22955139

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

2012-10-01

195

The Tandem-ALPI-PIAVE accelerator complex of LNL  

SciTech Connect

Heavy ion beams are delivered at the Laboratori Nazionali di Legnaro by the accelerator complex Tandem-ALPI-PIAVE. The Tandem XTU is a Van de Graaff accelerator normally operated at terminal voltages of up to about 15 MV. The Tandem accelerator can be operated in stand-alone mode or as an injector for the linac booster ALPI. The linear accelerator ALPI is built of superconducting resonant cavities and consists of a low-beta branch, particularly important for the acceleration of the heavier mass ions, a medium-beta branch, and a high-beta branch. ALPI can be operated also with the PIAVE injector that consists of a superconducting linac and an ECR source. The PIAVE source was mainly used for the acceleration of intense noble gas beams but most recently also a first metallic beam was delivered to the users. The accelerator complex delivers beams of ions from protons to gold in three experimental areas on 11 different beam lines. A rich scientific activity is ongoing at the Tandem-ALPI-PIAVE accelerator complex, beam time being shared between nuclear physics research and applied and interdisciplinary physics research. An overview of the present status and perspectives of the Tandem-ALPI-PIAVE complex and its physics program is given in the present paper.

Ur, C. A. [INFN Sezione di Padova, 35131 Padova (Italy)

2013-07-18

196

The design and numerical analysis of tandem thermophotovoltaic cells  

NASA Astrophysics Data System (ADS)

In this paper, numerical analysis of GaSb =(Eg = 0.72 eV)/Ga0.84In0.16As0.14Sb0.86 (Eg = 0.53 eV) tandem thermophotovoltaic (TPV) cells is carried out by using Silvaco/Atlas software. In the tandem cells, a GaSb p-n homojunction is used for the top cell and a GaInAsSb p-n homojunction for the bottom cell. A heavily doped GaSb tunnel junction connects the two sub-cells together. The simulations are carried out at a radiator temperature of 2000 K and a cell temperature of 300 K. The radiation photons are injected from the top of the tandem cells. Key properties of the single- and dual-junction TPV cells, including I-V characteristic, maximum output power (Pmax), open-circuit voltage (Voc), short-circuit current (Isc), etc. are presented. The effects of the sub-cell thickness and carrier concentration on the key properties of tandem cells are investigated. A comparison of the dual-TPV cells with GaSb and GaInAsSb single junction cells shows that the Pmax of tandem cells is almost twice as great as that of the single-junction cells.

Yang, Hao-Yu; Liu, Ren-Jun; Wang, Lian-Kai; Lü, You; Li, Tian-Tian; Li, Guo-Xing; Zhang, Yuan-Tao; Zhang, Bao-Lin

2013-10-01

197

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

198

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

199

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

200

Tandem photovoltaic solar cells and increased solar energy conversion efficiency  

NASA Technical Reports Server (NTRS)

Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

Loferski, J. J.

1976-01-01

201

Silicon based tandem cells: novel photocathodes for hydrogen production.  

PubMed

A photovoltaic tandem cell made of amorphous silicon (a-Si) and microcrystalline silicon (?c-Si) was investigated as a photocathode for hydrogen evolution in a photoelectrochemical device. The electronic and electrochemical properties of the samples were characterized using X-ray photoemission spectroscopy (XPS) and cyclic voltammetry (CV), whereas the morphology of the surface in contact with the electrolyte was investigated by scanning electron microscopy (SEM). The electric efficiency of the tandem cell was determined to be 5.2% in a photoelectrochemical (PEC) setup in acidic solution which is only about half of the photovoltaic efficiency of the tandem cell. A significant improvement in efficiency was achieved with platinum as a catalyst which was deposited by physical vapour deposition (PVD) under ultra-high vacuum (UHV) conditions. PMID:24710175

Calvet, W; Murugasen, E; Klett, J; Kaiser, B; Jaegermann, W; Finger, F; Hoch, S; Blug, M; Busse, J

2014-05-28

202

Tandem immunoprecipitation approach to identify HIV-1 Gag associated host factors.  

PubMed

HIV-1 Gag by itself is able to assemble and release from host cells and thus serves as a simplified model to identify host factors involved in this stage of the HIV-1 life cycle. In this study, a tandem immunoprecipitation approach is taken to immunoprecipitate Gag-interacting host proteins from transfected 293T cells. It is demonstrated that with the tandem immunoprecipitation method Gag-interacting host factors can be precipitated more efficiently than by single-step immunoprecipitation. Gag proteins are found to interact with multiple RNA-binding proteins such as hnRNPs, nucleolin, EF1a and ribosomal proteins. Such interactions are mediated by cellular RNAs and the Gag Nuclear Capsid (NC) domain. Deletion of the NC domain results in removal of most of the RNA-binding proteins, as well as a reduction of the Gag releasing capability, which can be restored by replacing the deleted NC domain with another multimerization motif. Importantly, interactions between Gag and host factors are relevant functionally, as evidenced by significantly increased nucleolin protein in the cytoplasm where it is recruited into the Gag complex, and enhanced Gag release when nucleolin is over-expressed. PMID:24690621

Gao, Wei; Li, Min; Zhang, Jingxin

2014-07-01

203

Sites in the AAV5 capsid tolerant to deletions and tandem duplications  

PubMed Central

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 >105 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.

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

2010-01-01

204

Analysis of amprolium by hydrophilic interaction liquid chromatography-tandem mass spectrometry.  

PubMed

We present a fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of the coccidiostat amprolium in food samples. Tandem mass spectrometry in a triple quadrupole was used for quantitative purposes, and the information from multiple-stage mass spectrometry in an ion-trap mass analyzer contributed to fragmentation studies. Hydrophilic interaction liquid chromatography (HILIC) in a Fused-Core column using isocratic elution (acetonitrile:formic acid/ammonium formate buffer pH 4, 50 mM (60:40)) successfully analyzed this compound in less than 3 min. The HILIC system was coupled to heated electrospray-MS/MS using highly selective-selected reaction monitoring (H-SRM) to improve sensitivity and selectivity for the analysis of amprolium, after a simple sample treatment based on an "extract and shoot" strategy. Accurate mass measurements were performed to identify the interfering compound responsible for causing matrix ion enhancement in the signal of amprolium. The addition of l-carnitine (the interfering compound) (1 microg L(-1)) to standards and sample extracts allowed the use of the external calibration method for quantitative purposes. The LC-MS/MS (H-SRM) method showed good precision (relative standard deviation, RSD, lower than 13%), accuracy and linearity and allowed the determination of amprolium down to the ppb level (LODs between 0.1 and 0.6 microg kg(-1)). PMID:20696436

Martínez-Villalba, Anna; Moyano, Encarnación; Galceran, M Teresa

2010-09-10

205

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

206

Tandem Cycloisomerization/Suzuki Coupling of Arylethynyl MIDA Boronates  

PubMed Central

A tandem gold-catalyzed cycloisomerization/Suzuki cross coupling sequence involving arylethynyl-N-methyliminodiacetic acid boronates is described. Combining the mildness of homogeneous gold catalysis with the versatility of N-methyliminodiacetic acid (MIDA) boronates, this tandem two-step method enables the rapid assembly of various aryl-substituted heterocycles without having to isolate or purify any heterocyclic MIDA boronate intermediates. Another major advantage of this method is that a wide range of heterocycles bearing different aryl groups may be made from a single MIDA boronate alkyne precursor.

Chan, Julian M. W.; Amarante, Giovanni W.; Toste, F. Dean

2011-01-01

207

A tandem calibration method for kerma area product meters  

NASA Astrophysics Data System (ADS)

For measurements of the kerma-area product (KAP) in diagnostic x-ray imaging, a method for calibrating field KAP meters with a reference KAP meter is presented. In this tandem calibration method, the field KAP chamber is positioned similarly as in measurements with patients. The reference KAP chamber is placed at a specified distance and used in the x-ray beam simultaneously with the field KAP chamber. The tandem method provides a feasible and practical way for calibrating field KAP meters of any type in their clinical position. Accurate measurements of the irradiation geometry are not required, but comprehensive calibration for the reference KAP meter is needed.

Toroi, P.; Komppa, T.; Kosunen, A.

2008-09-01

208

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

209

III-V\\/Silicon Lattice-Matched Tandem Solar Cells  

Microsoft Academic Search

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

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

2005-01-01

210

A tandem calibration method for kerma-area product meters.  

PubMed

For measurements of the kerma-area product (KAP) in diagnostic x-ray imaging, a method for calibrating field KAP meters with a reference KAP meter is presented. In this tandem calibration method, the field KAP chamber is positioned similarly as in measurements with patients. The reference KAP chamber is placed at a specified distance and used in the x-ray beam simultaneously with the field KAP chamber. The tandem method provides a feasible and practical way for calibrating field KAP meters of any type in their clinical position. Accurate measurements of the irradiation geometry are not required, but comprehensive calibration for the reference KAP meter is needed. PMID:18711243

Toroi, P; Komppa, T; Kosunen, A

2008-09-21

211

Highly charged ion injector in the terminal of tandem accelerator  

NASA Astrophysics Data System (ADS)

A highly charged heavy ion injector using an all permanent magnet type electron cyclotron resonance ion source (ECRIS) has been constructed in the high voltage terminal of the vertical and folded type 20UR Pelletron tandem accelerator at Japan Atomic Energy Agency at Tokai. The new in-terminal injector made it possible to accelerate highly charged heavy ions which have not been obtained from the tandem accelerator. Beam energy and beam intensity have been remarkably increased and the noble gas ion beams have become available.

Matsuda, M.; Asozu, T.; Nakanoya, T.; Kutsukake, K.; Hanashima, S.; Takeuchi, S.

2009-04-01

212

Potent activation of the human tandem pore domain K channel TRESK with clinical concentrations of volatile anesthetics.  

PubMed

The tandem pore domain K channel family mediates background K currents present in excitable cells. Currents passed by certain members of the family are enhanced by volatile anesthetics, thus suggesting a novel mechanism of anesthesia. The newest member of the family, termed TRESK (TWIK [tandem pore domain weak inward rectifying channel]-related spinal cord K channel), has not been studied for anesthetic sensitivity. We isolated the coding sequence for TRESK from human spinal cord RNA and functionally expressed it in Xenopus oocytes and transfected COS-7 cells. With both whole-cell voltage-clamp and patch-clamp recording, TRESK currents increased up to three-fold by clinical concentrations of isoflurane, halothane, sevoflurane, and desflurane. Nonanesthetics (nonimmobilizers) had no effect on TRESK. Various IV anesthetics, including etomidate, thiopental, and propofol, have a minimal effect on TRESK currents. Amide and ester local anesthetics inhibit TRESK in a concentration-dependent manner but at concentrations generally larger than those that inhibit other tandem pore domain K channels. We also determined that TRESK is found not only in spinal cord, but also in human brain RNA. These results identify TRESK as a target of volatile anesthetics and suggest a role for this background K channel in mediating the effects of inhaled anesthetics in the central nervous system. PMID:15562060

Liu, Canhui; Au, John D; Zou, Hilary Liao; Cotten, Joseph F; Yost, C Spencer

2004-12-01

213

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

214

Development of high band gap materials for tandem solar cells and simulation studies on mechanical tandem solar cells  

NASA Astrophysics Data System (ADS)

Development of low cost, high efficiency tandem solar cells is essential for large scale adoption of solar energy especially in densely populated regions of the world. In this thesis four-terminal mechanical (stack like) tandem solar cells were evaluated using detailed simulation models and design criteria for selecting candidate materials were established. Since silicon solar cells are low cost and have a multi-giga watt global manufacturing and supply chain capacity already in place then only tandem stacks incorporating silicon as one of the layers in the device was investigated. Two candidate materials which have high band gaps that could be used as top cells in the mechanical tandem device were explored as part of the thesis. Dye-sensitized solar cells (DSSC) sensitized with N719 dye (one of the candidates for the top cell) were fabricated with the goal of enabling a flexible processing path to lower cost. Stainless steel (SS) mesh substrates were used to fabricate anodes for flexible DSSC in order to evaluate them as replacements for more expensive Transparent Conducting Oxides (TCO's). Loss mechanisms in DSSC's due to SS mesh oxidation were quantified and protective coatings to prevent oxidation of SS mesh were developed. The second material which was evaluated for use as the top cell was copper zinc tin sulfide (CZTS). CZTS was deposited through a solution deposition route. Detailed investigations were done on the deposited films to understand the chemistry, crystal structure and its opto-electronic properties. Deposited CZTS films were found to be highly crystalline in <112> direction. The films had a direct band gap of 1.5 eV with absorption coefficient greater than 104 cm -1 in agreement with published values. In the second part of the thesis detailed electrical and optical simulation models of the mechanical tandem solar cells were developed based on the most up-to-date materials physical constants available for each layer. The modeling was used to quantify the various theoretical and practical loss mechanisms in tandem devices. Two configurations were evaluated, first was silicon / germanium tandem cell and the second was gallium arsenide / silicon tandem cell. The simulation models were validated by their close match to the performance of experimental standalone solar cells devices reported in the literature. Finally the efficiency limits of the present generation of high band gap solar cells were discussed. Voltage and current loss of the high band gap solar cells were compared with present generation silicon solar cells and challenges in improving their efficiencies were described.

Vijayakumar, Vishnuvardhanan

215

Structural Studies of the Tandem Tudor Domains of Fragile X Mental Retardation Related Proteins FXR1 and FXR2  

PubMed Central

Background Expansion of the CGG trinucleotide repeat in the 5?-untranslated region of the FMR1, fragile X mental retardation 1, gene results in suppression of protein expression for this gene and is the underlying cause of Fragile X syndrome. In unaffected individuals, the FMRP protein, together with two additional paralogues (Fragile X Mental Retardation Syndrome-related Protein 1 and 2), associates with mRNA to form a ribonucleoprotein complex in the nucleus that is transported to dendrites and spines of neuronal cells. It is thought that the fragile X family of proteins contributes to the regulation of protein synthesis at sites where mRNAs are locally translated in response to stimuli. Methodology/Principal Findings Here, we report the X-ray crystal structures of the non-canonical nuclear localization signals of the FXR1 and FXR2 autosomal paralogues of FMRP, which were determined at 2.50 and 1.92 Å, respectively. The nuclear localization signals of the FXR1 and FXR2 comprise tandem Tudor domain architectures, closely resembling that of UHRF1, which is proposed to bind methylated histone H3K9. Conclusions The FMRP, FXR1 and FXR2 proteins comprise a small family of highly conserved proteins that appear to be important in translational regulation, particularly in neuronal cells. The crystal structures of the N-terminal tandem Tudor domains of FXR1 and FXR2 revealed a conserved architecture with that of FMRP. Biochemical analysis of the tandem Tudor doamins reveals their ability to preferentially recognize trimethylated peptides in a sequence-specific manner. 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.

Adams-Cioaba, Melanie A.; Guo, Yahong; Bian, ChuanBing; Amaya, Maria F.; Lam, Robert; Wasney, Gregory A.; Vedadi, Masoud; Xu, Chao; Min, Jinrong

2010-01-01

216

A census of Tandem system availability between 1985 and 1990  

Microsoft Academic Search

A census of customer outages reported to Tandem showing a clear improvement in the reliability of hardware and maintenance has been taken. It indicates that software is now the major source of reported outages (62%), followed by system operations (15%). This is a dramatic shift from the statistics for 1985. Even after discounting systematic underreporting of operations and environmental outages,

J. Gray

1990-01-01

217

Tandem warhead considerations for electronic safety and arming devices  

SciTech Connect

There are four issues that an ESA designer must address when designing a tandem system: (1) warhead detonation shock, (2) warhead detonation ion cloud, (3) warhead detonation electromagnetic pulse, and (4) slapper/sparkgap electromagnetic pulse. Each of these hazards can upset the ESA time delay circuitry which would then either dud the munition or prematurely detonate the main charge. 14 figs.

Dell, D.; Medina, A.

1990-01-01

218

Tandem warhead considerations for electronic safety and arming devices  

Microsoft Academic Search

There are four issues that an ESA designer must address when designing a tandem system: (1) warhead detonation shock, (2) warhead detonation ion cloud, (3) warhead detonation electromagnetic pulse, and (4) slapper\\/sparkgap electromagnetic pulse. Each of these hazards can upset the ESA time delay circuitry which would then either dud the munition or prematurely detonate the main charge. 14 figs.

A. Medina

1990-01-01

219

Analysis of Short Tandem Repeats by Parallel DNA Threading  

Microsoft Academic Search

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

Pawel Zajac; Christine Öberg; Afshin Ahmadian

2009-01-01

220

An investigation of the tyrothricin complex by tandem mass spectrometry  

NASA Astrophysics Data System (ADS)

Tandem mass spectrometry has been shown to be a powerful technique for determining the structures of biological compounds. This paper details the mass spectrometric methods employed to characterise the structural variations found within a mixture of cyclic decapeptides, tyrothricin, produced by the bacterium Bacillus brevis.

Barber, M.; Bell, D. J.; Morris, M. R.; Tetler, L. W.; Monaghan, J. J.; Morden, W. E.; Bycroft, B. W.; Green, B. N.

1992-12-01

221

High efficiency GaAs/Ge monolithic tandem solar cells  

NASA Technical Reports Server (NTRS)

Two-terminal monolithic tandem cells consisting of a GaAs solar cell grown epitaxially on a Ge solar cell substrate are very attractive for space applications. Tandem cells of GaAs grown by metal-organic chemical vapor deposition on thin Ge were investigated to address both higher efficiency and reduced weight. Two materials growth issues associated with this heteroepitaxial system, autodoping of the GaAs layers by Ge and diffusion of Ga and As into the Ge substrate, were addressed. The latter appears to result in information of an unintentional p-n junction in the Ge. Early simulator measurements gave efficiencies as high as 21.7 percent for 4 cm2 GaAs/Ge cells, but recent high-altitude testing has given efficiencies of 18 percent. Sources of errors in simulator measurements of two-terminal tandem cells are discussed. A limiting efficiency of about 36 percent for the tandem cell at AMO was calculated. Ways to improve the performance of present cells, primarily by increasing the Isc and Voc of the Ge cell, are proposed.

Tobin, S. P.; Vernon, S. M.; Bajgar, C.; Haven, V. E.; Geoffroy, L. M.; Sanfacon, M. M.; Lillington, D. R.; Hart, R. E., Jr.

1988-01-01

222

Dynamics of tandem bubble interaction in a microfluidic channel.  

PubMed

The dynamics of tandem bubble interaction in a microfluidic channel (800? × ?21 ?m, W?×?H) have been investigated using high-speed photography, with resultant fluid motion characterized by particle imaging velocimetry. A single or tandem bubble is produced reliably via laser absorption by micron-sized gold dots (6 ?m in diameter with 40 ?m in separation distance) coated on a glass surface of the microfluidic channel. Using two pulsed Nd:YAG lasers at ??=?1064 nm and ?10 ?J/pulse, the dynamics of tandem bubble interaction (individual maximum bubble diameter of 50 ?m with a corresponding collapse time of 5.7 ?s) are examined at different phase delays. In close proximity (i.e., interbubble distance?=?40 ?m or ??=?0.8), the tandem bubbles interact strongly with each other, leading to asymmetric deformation of the bubble walls and jet formation, as well as the production of two pairs of vortices in the surrounding fluid rotating in opposite directions. The direction and speed of the jet (up to 95 m/s), as well as the orientation and strength of the vortices can be varied by adjusting the phase delay. PMID:22088007

Yuan, Fang; Sankin, Georgy; Zhong, Pei

2011-11-01

223

Finding all sorting tandem duplication random loss operations  

Microsoft Academic Search

A tandem duplication random loss (TDRL) operation duplicates a contiguous segment of genes, followed by the random loss of one copy of each of the duplicated genes. Although the importance of this operation is founded by several recent biological studies, it has been investigated only rarely from a theoretical point of view. Of particular interest are sorting TDRLs which are

Matthias Bernt; Kuan-Yu Chen; Ming-Chiang Chen; An-Chiang Chu; Daniel Merkle; Hung-Lung Wang; Kun-Mao Chao; Martin Middendorf

2011-01-01

224

Computing Positional Isotopomer Distributions from Tandem Mass Spectrometric Data  

Microsoft Academic Search

The isotopomer distributions of metabolites are invaluable pieces of information in the computation of the flux distribution in a metabolic network. We describe the use of tandem mass spectrometry with the daughter ion scanning technique in the discovery of positional isotopomer distributions (PID). This technique increases the possibilities of mass spectrometry since given the same fragment ions, it uncovers more

Ari Rantanen; Juho Rousu; Juha T. Kokkonen; Virpi Tarkiainen; Raimo A. Ketola

2002-01-01

225

Electrostatic plasma-confinement experiments in a tandem mirror system  

Microsoft Academic Search

Results from the tandem mirror experiment are described. The configuration of axial density and potential profiles are created and sustained by neutral-beam injection and gas fueling. Plasma confinement in the center cell is shown to be improved by the end plugs by as much as a factor of 9. The electron temperature is higher than that achieved in our earlier

F. H. Coensgen; C. A. Anderson; T. A. Casper; J. F. Clauser; W. C. Condit; D. L. Correll; W. F. Cummins; J. C. Davis; R. P. Drake; J. H. Foote; A. H. Futch; R. K. Goodman; D. P. Grubb; G. A. Hallock; R. S. Hornady; A. L. Hunt; B. G. Logan; R. H. Munger; W. E. Nexsen; T. C. Simonen; D. R. Slaughter; B. W. Stallard; O. T. Strand

1980-01-01

226

Orbit Averaged Radial Buildup Code for Tandem Mirror Geometry.  

National Technical Information Service (NTIS)

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 cente...

M. Campbell A. H. Futch

1981-01-01

227

Integrating structure and function of 'tandem-repeat' galectins.  

PubMed

Galectins (GALs) are evolutionarily-conserved lectins defined by at least one carbohydrate recognition domain (CRD) with affinity for beta-galactosides and conserved sequence motifs. Although the biological roles of some members of this family, including the 'proto-type' GAL-1 and the 'chimera-type' GAL-3 have been widely studied, the functions of 'tandem-repeat' galectins are just emerging. The subgroup of 'tandem-repeat' galectins (GAL-4, -6, -8, -9, and -12) contain two distinct CRDs, connected by a linker peptide. Here we integrated and distilled the available information on 'tandem-repeat' galectins, their specific structures, potential ligands and biological activities in inflammatory and neoplastic diseases. While GAL-4 has been implicated in inflammatory bowel diseases, either as a pro-inflammatory or pro-apoptotic mediator, GAL-8 plays roles in autoimmune diseases such as rheumatoid arthritis and lupus erythematosus and modulates tumor progression. GAL-9 controls allergic inflammation and Th1/Th17-mediated autoimmunity and has prognostic value in certain tumor types. Finally, GAL-12 plays important roles in adipocyte physiology. Although this information is just emerging, further studies are needed to dissect the biological roles of 'tandem-repeat' galectins in health and disease. PMID:22202096

Troncoso, Maria F; Elola, Maria T; Croci, Diego O; Rabinovich, Gabriel A

2012-01-01

228

Numerical simulation for flow around two circular cylinders in tandem  

Microsoft Academic Search

We use a third-order upwind finite element scheme in order to perform numerical stabilization of solutions of the Navier Stokes equations and present numerical results of flow around two circular cylinders in tandem arrangement by two- and three-dimensional computations. The two circular cylinders are arranged with some spacings between the cylinders. It is well known from experimental data that the

Norio Kondo; Daisuke Matsukuma

2005-01-01

229

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

230

Charge State Estimation for Tandem Mass Spectrometry Proteomics  

Microsoft Academic Search

High-throughput protein analysis by tandem mass spectrometry produces anywhere from thousands to millions of spectra that are being used for peptide and protein identifications. Though each spectrum corresponds only to one charged peptide (ion) state, repetitive data- base searches of multiple charge states are typically conducted since the resolution of many common mass spectrometers is not sufficient to determine the

Jason M. Hogan; Roger Higdon; Natali Kolker; Eugene Kolker

2005-01-01

231

Efficient tandem and triple-junction polymer solar cells.  

PubMed

We demonstrate tandem and triple-junction polymer solar cells with power conversion efficiencies of 8.9% and 9.6% that use a newly designed, high molecular weight, small band gap semiconducting polymer and a matching wide band gap polymer. PMID:23544881

Li, Weiwei; Furlan, Alice; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2013-04-17

232

Bolt Stop for Use with Tandem-Type Magazines.  

National Technical Information Service (NTIS)

The firearm has a receiver and a barrel with a chamber. The receiver is provided with a magazine well for receiving a tandem type magazine. The magazine has front and rear compartments. A bolt stop is provided which is delayed one cycle after the last car...

R. Meunier

1965-01-01

233

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

234

Short tandem repeat (STR) genotyping of keratinised hair  

Microsoft Academic Search

We present a review of the literature on procedures for obtaining short tandem repeat (STR) genotypes from keratinised hair, being either hair shaft or telogen phase (naturally shed) hairs without associated scalp, follicle or sheath cells. Both the hair shaft and the telogen hair club have been subjected to the DNA-degrading keratinisation process and are more likely to be found

Dennis McNevin; Linzi Wilson-Wilde; James Robertson; Jennelle Kyd; Chris Lennard

2005-01-01

235

Progress report on Aramis, the 2 MV tandem at Orsay  

Microsoft Academic Search

Aramis is a home built multipurpose 2 MV electrostatic tandem accelerator. A large variety of ions are available for high energy implantation. Characterization possibilities are also quite large in the Van de Graaff mode owing to the Penning positive ion source in the terminal. A second beam line is now available that sends the beam into the target chamber of

H. Bernas; J. Chaumont; E. Cottereau; R. Meunier; A. Traverse; C. Clerc; O. Kaitasov; F. Lalu; D. Le Du; G. Moroy; M. Salomé

1992-01-01

236

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  

PubMed Central

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

2013-01-01

237

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

238

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

239

Development of an advanced spacecraft tandem mass spectrometer  

NASA Technical Reports Server (NTRS)

The purpose of this research was to apply current advanced technology in electronics and materials to the development of a miniaturized Tandem Mass Spectrometer that would have the potential for future development into a package suitable for spacecraft use. The mass spectrometer to be used as a basis for the tandem instrument would be a magnetic sector instrument, of Nier-Johnson configuration, as used on the Viking Mars Lander mission. This instrument configuration would then be matched with a suitable second stage MS to provide the benefits of tandem MS operation for rapid identification of unknown organic compounds. This tandem instrument is configured with a newly designed GC system to aid in separation of complex mixtures prior to MS analysis. A number of important results were achieved in the course of this project. Among them were the development of a miniaturized GC subsystem, with a unique desorber-injector, fully temperature feedback controlled oven with powered cooling for rapid reset to ambient conditions, a unique combination inlet system to the MS that provides for both membrane sampling and direct capillary column sample transfer, a compact and ruggedized alignment configuration for the MS, an improved ion source design for increased sensitivity, and a simple, rugged tandem MS configuration that is particularly adaptable to spacecraft use because of its low power and low vacuum pumping requirements. The potential applications of this research include use in manned spacecraft like the space station as a real-time detection and warning device for the presence of potentially harmful trace contaminants of the spacecraft atmosphere, use as an analytical device for evaluating samples collected on the Moon or a planetary surface, or even use in connection with monitoring potentially hazardous conditions that may exist in terrestrial locations such as launch pads, environmental test chambers or other sensitive areas. Commercial development of the technology could lead to a new family of environmental test instruments that would be small and portable, yet would give quick analyses of complex samples.

Drew, Russell C.

1992-01-01

240

Monolithic Parallel Tandem Organic Photovoltaic Cell with Transparent Carbon Nanotube Interlayer  

NASA Technical Reports Server (NTRS)

We demonstrate an organic photovoltaic cell with a monolithic tandem structure in parallel connection. Transparent multiwalled carbon nanotube sheets are used as an interlayer anode electrode for this parallel tandem. The characteristics of front and back cells are measured independently. The short circuit current density of the parallel tandem cell is larger than the currents of each individual cell. The wavelength dependence of photocurrent for the parallel tandem cell shows the superposition spectrum of the two spectral sensitivities of the front and back cells. The monolithic three-electrode photovoltaic cell indeed operates as a parallel tandem with improved efficiency.

Tanaka, S.; Mielczarek, K.; Ovalle-Robles, R.; Wang, B.; Hsu, D.; Zakhidov, A. A.

2009-01-01

241

?-BaB 2O 4 deep UV monolithic walk-off compensating tandem  

NASA Astrophysics Data System (ADS)

The generation of watt-level cw narrow-linewidth sources at specific deep-UV wavelengths corresponding to atomic cooling transitions usually employs external cavity-enhanced second-harmonic generation (SHG) of moderate-power visible lasers in birefringent materials. Among the oxo-borate materials, barium borate (?-BaB 2O 4 or BBO) combines the highest UV band edge and largest nonlinearity but suffers from large walk-off angles that limits the nonlinear interaction length. Alternative quasi-phase-matched (QPM) ferroelectrics are hardly suited for cavity-enhanced operation due to their much larger UV absorption and associated photo-refractive and thermal lensing effects, in addition to the difficult fabrication of fine-pitch domain gratings for short UV coherence lengths. In this work, we investigate an alternative approach to cw deep-UV generation by employing the low-loss BBO in a monolithic walk-off compensating structure [J.-J. Zondy, Ch. Bonnin, D. Lupinski, J. Opt. Soc. Am. B 20 (2003) 1675] to simultaneously enhance the effective nonlinear coefficient while minimizing the UV beam ellipticity under tight focusing. As a preliminary step to cavity-enhanced operation, and in order to apprehend the design difficulties stemming from the extremely low acceptance angle of BBO, we investigate and analyze the single-pass performance of a Lc = 8 mm monolithic walk-off compensating structure made of 2 optically-contacted BBO plates cut for type-I critically phase-matched SHG of a cw ? = 570.4 nm dye laser. As compared with a bulk crystal of identical length, a sharp UV efficiency enhancement factor of 1.65 has been evidenced with the tandem structure, but at ˜-1 nm from the targeted fundamental wavelength, highlighting the sensitivity of this technique when applied to a highly birefringent material such as BBO. Solutions to angle cut residual errors are identified so as to match accurately more complex periodic-tandem structure performance to any target UV wavelength, opening the prospect for high-power, good beam quality deep-UV cw laser sources for atom cooling and trapping.

Friebe, J.; Moldenhauer, K.; Rasel, E. M.; Ertmer, W.; Isaenko, L.; Yelisseyev, A.; Zondy, J.-J.

2006-05-01

242

Propulsive performance of unsteady tandem hydrofoils in a side-by-side configuration  

NASA Astrophysics Data System (ADS)

Experimental and analytical results are presented on two identical bio-inspired hydrofoils oscillating in a side-by-side configuration. The time-averaged thrust production and power input to the fluid are found to depend on both the oscillation phase differential and the transverse spacing between the foils. For in-phase oscillations, the foils exhibit an enhanced propulsive efficiency at the cost of a reduction in thrust. For out-of-phase oscillations, the foils exhibit enhanced thrust with no observable change in the propulsive efficiency. For oscillations at intermediate phase differentials, one of the foils experiences a thrust and efficiency enhancement while the other experiences a reduction in thrust and efficiency. Flow visualizations reveal how the wake interactions lead to the variations in propulsive performance. Vortices shed into the wake from the tandem foils form vortex pairs rather than vortex streets. For in-phase oscillation, the vortex pairs induce a momentum jet that angles towards the centerplane between the foils, while out-of-phase oscillations produce vortex pairs that angle away from the centerplane between the foils.

Dewey, Peter A.; Quinn, Daniel B.; Boschitsch, Birgitt M.; Smits, Alexander J.

2014-04-01

243

Fully integrated, fully automated generation of short tandem repeat profiles  

PubMed Central

Background The generation of short tandem repeat profiles, also referred to as ‘DNA typing,’ is not currently performed outside the laboratory because the process requires highly skilled technical operators and a controlled laboratory environment and infrastructure with several specialized instruments. The goal of this work was to develop a fully integrated system for the automated generation of short tandem repeat profiles from buccal swab samples, to improve forensic laboratory process flow as well as to enable short tandem repeat profile generation to be performed in police stations and in field-forward military, intelligence, and homeland security settings. Results An integrated system was developed consisting of an injection-molded microfluidic BioChipSet cassette, a ruggedized instrument, and expert system software. For each of five buccal swabs, the system purifies DNA using guanidinium-based lysis and silica binding, amplifies 15 short tandem repeat loci and the amelogenin locus, electrophoretically separates the resulting amplicons, and generates a profile. No operator processing of the samples is required, and the time from swab insertion to profile generation is 84 minutes. All required reagents are contained within the BioChipSet cassette; these consist of a lyophilized polymerase chain reaction mix and liquids for purification and electrophoretic separation. Profiles obtained from fully automated runs demonstrate that the integrated system generates concordant short tandem repeat profiles. The system exhibits single-base resolution from 100 to greater than 500 bases, with inter-run precision with a standard deviation of ±0.05 - 0.10 bases for most alleles. The reagents are stable for at least 6 months at 22°C, and the instrument has been designed and tested to Military Standard 810F for shock and vibration ruggedization. A nontechnical user can operate the system within or outside the laboratory. Conclusions The integrated system represents the first generation of a turnkey approach to short tandem repeat profiling and has the potential for use in both the field (for example, police booking stations, the battlefield, borders and ports) and the forensic laboratory.

2013-01-01

244

A T-cell specific transcriptional enhancer element 3 prime of C sub. alpha. in the human T-cell receptor. alpha. locus  

SciTech Connect

A transcriptional enhancer element has been identified 4.5 kilobases 3{prime} of C{sub {alpha}} (constant region {alpha} chain) in the human T-cell receptor (TCR) {alpha}-chain locus. This enhancer is active on both a TCR V{sub {alpha}} (variable region {alpha} chain) promoter and the minimal simian virus 40 promoter in TCR {alpha}/{beta} Jurkat and EL4 cells but is inactive on a V{sub {alpha}} promoter TCR {gamma}/{delta} PEER and Molt-13 cells, clone 13 B cells, and HeLa fibroblasts. The enhancer has been localized to a 116-base-pair BstXI/Dra I restriction enzyme fragment, which lacks immunoglobulin octamer and {kappa}B enhancer motifs but does contain a consensus cAMP-response element (CRE). DNase I footprint analyses demonstrated that the minimal enhancer contains two binding sites for Jurkat nuclear proteins. One of these sites corresponds to the CRE, while the other does not correspond to a known transcriptional enhancer motif. These data support a model in which TCR {alpha} gene transcription is regulated by a unique set of cis-acting sequences and trans-acting factors, which are differentially active in cells of the TCR {alpha}/{beta} lineage. In addition, the TCR {alpha} enhancer may play a role in activating oncogene expression in T-lymphoblastoid tumors that have previously been shown to display chromosomal translocations into the human TCR {alpha} locus.

Ho, Icheng; Yang, Lihsuan; Morle, G.; Leiden, J.M. (Univ of Michigan Medical Center, Ann Arbor (USA))

1989-09-01

245

Advantages of atmospheric pressure chemical ionization in gas chromatography tandem mass spectrometry: pyrethroid insecticides as a case study.  

PubMed

Gas chromatography coupled to mass spectrometry (GC/MS) has been extensively applied for determination of volatile, nonpolar, compounds in many applied fields like food safety, environment, or toxicology. The wide majority of methods reported use electron ionization (EI), which may result in extensive fragmentation of analytes compromising selectivity and sensitivity. This might also complicate the application of tandem MS due to lack of specific/abundant precursor ions. Pyrethroids are examples of compounds with this behavior. In this work, the potential of atmospheric pressure chemical ionization (APCI), a softer form of ionization, combined with GC and a triple quadrupole mass analyzer was investigated, taking pyrethroids as a case study and their determination in fruit and vegetables as example application. Ionization and fragmentation behavior of eight pyrethroids (bifenthrin, cyfluthrin, cypermethrin, permethrin, ?-cyhalothrin, fluvalinate, fenvalerate, and deltamethrin) by APCI were studied. The formation of a highly abundant (quasi) molecular ion was the main goal because of the enhanced selectivity when used as precursor ion in tandem MS. The addition of water as a modifier was tested to promote the generation of protonated molecules, resulting in notable improvement of sensitivity and selectivity for most compounds. The excellent detectability (low detection limits (LODs) <20 fg achieved) when using APCI combined with state-of-the-art tandem MS was demonstrated for real samples. Additionally, matrix effects were evaluated in terms of signal enhancement/suppression. Depending on the matrix, different degrees of suppression were observed, on average reducing the signal in matrix to 55% of that in solvent. The results presented in this paper demonstrate the potential of APCI as new source for GC/MS that could be applied to other analytical problems apart from those illustrated in this work. PMID:23006011

Portolés, T; Mol, J G J; Sancho, J V; Hernández, F

2012-11-20

246

Summary of results from the Tandem Mirror Experiment (TMX)  

SciTech Connect

This report summarizes results from the successful experimental operation of the Tandem Mirror Experiment (TMX) over the period October 1978 through September 1980. The experimental program, summarized by the DOE milestones given in Table 1-1, had three basic phases: (1) an 8-month checkout period, October 1978 through May 1979; (2) a 6-month initial period of operation, June through November 1979, during which the basic principles of the tandem configuration were demonstrated (i.e., plasma confinement was improved over that of a single-cell mirror); and (3) a 10-month period, December 1979 through September 1980, during which the initial TMX results were corroborated by additional diagnostic measurements and many detailed physics investigations were carried out. This report summarizes the early results, presents results of recent data analysis, and outlines areas of ongoing research and data analysis which will be reported in future journal publications.

Simonen, T.C. (ed.)

1981-02-26

247

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

248

Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry of Carotenoids  

PubMed Central

Carotenoids are natural pigments synthesized by plants and photosynthetic microorganisms, some of which, like ?-carotene, are precursors of vitamin A, and others such as lutein and lycopene might function in the prevention of age-related macular degeneration and prostate cancer, respectively. Mass spectrometry provides high sensitivity and selectivity for the identification and quantitative analysis of carotenoids in biological samples, and previous studies have described how atmospheric pressure chemical ionization (APCI) offers distinct advantages over electrospray and fast atom bombardment for the analysis of specific carotenoids. Since APCI product ion tandem mass spectra have been reported for only a few carotenoids, a detailed investigation of twelve carotenes and xanthophylls was carried out using both positive ion and negative ion APCI tandem mass spectrometry with collision-induced dissociation. Using protonated molecules as precursor ions in positive ion mode and radical anions in negative ion mode, characteristic fragment ions were identified that may be used to distinguish between carotenoids.

van Breemen, Richard B.; Dong, Linlin; Pajkovic, Natasa D.

2011-01-01

249

MINIMARS: An attractive small tandem mirror fusion reactor  

NASA Astrophysics Data System (ADS)

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 systems, and multiplexing in station sizes of approx. 600 to 2400 MWe. We demonstrate that the compact octopole end cell provides a number of advantages over the more conventional quadrupole (yin-yang) end cell encountered in the MARS tandem mirror reactor study, and permits ignition to be achieved with much shorter central cell lengths. Accordingly, being economic in small sizes, MINIMARS provides an attractive alternative to the more conventional larger conceptual fusion reactors encountered to date, and would contribute significantly to the lowering of utility financial risk in a developing fusion economy.

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

1985-11-01

250

Preparation of synthetic tandem-repetitive probes for DNA fingerprinting.  

PubMed

DNA fingerprints are generated using probes that hybridize to hypervariable minisatellites, also known as variable number tandem repeat loci. Cloned minisatellites have served as the predominant source of DNA fingerprinting probes. A short segment within the repeat units of minisatellites, called the "core" sequence, is highly conserved within a family of related minisatellites, thereby allowing a single-cloned minisatellite to cross-hybridize to 20 to 40 other minisatellites. In this article, we describe a method for the synthetic preparation of polymeric core sequence probes for DNA fingerprinting. Unlike "monomeric" oligonucleotide probes, the polymeric probes mimic the tandem-repetitive structure of minisatellites, and thus each probe molecule can potentially form many sites of hybridization with a target minisatellite. The synthetic probes are cloned into plasmid DNA to provide a perpetual source of probe material. PMID:2400596

Ledwith, B J; Manam, S; Nichols, W W; Bradley, M O

1990-08-01

251

Superimposition and Analysis of ESI Tandem Mass Spectra.  

PubMed

Methionine enkephalin and four synthetic peptides (a heptapeptide and its modified form, a decapeptide and an icosapeptide) were fragmented using ESI tandem mass spectrometry with certain varying instrumental parameters, such as amplitude of excitation, to produce a series of MS/MS spectra. Using the Bruker DataAnalysis software, some complementary MS/MS spectra were chosen to form a superimposed MS/MS spectrum with consecutive triplets (as well as a few doublets) consisting of product ions AnBnCn or X n Y n Z n. The amino acid sequences of the peptides were easily and accurately determined from the superimposed MS/MS spectrum, suggesting that the method is easy and suitable for peptide sequencing by tandem mass spectrometry. PMID:12035059

Wang, X C; Liang, S P

2001-01-01

252

Challenges and developments in tandem mass spectrometry based clinical metabolomics.  

PubMed

'Clinical metabolomics' aims at evaluating and predicting health and disease risk in an individual by investigating metabolic signatures in body fluids or tissues, which are influenced by genetics, epigenetics, environmental exposures, diet, and behaviour. Powerful analytical techniques like liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) offers a rapid, effective and economical way to analyze metabolic alterations of pre-defined target metabolites in biological samples. Novel hyphenated technical approaches like the combination of tandem mass spectrometry combined with linear ion trap (QTrap mass spectrometry) combines both identification and quantification of known and unknown metabolic targets. We describe new concepts and developments of mass spectrometry based multi-target metabolome profiling in the field of clinical diagnostics and research. Particularly, the experiences from newborn screening provided important insights about the diagnostic potential of metabolite profiling arrays and directs to the clinical aim of predictive, preventive and personalized medicine by metabolomics. PMID:19007853

Ceglarek, Uta; Leichtle, Alexander; Brügel, Mathias; Kortz, Linda; Brauer, Romy; Bresler, Kristin; Thiery, Joachim; Fiedler, Georg Martin

2009-03-25

253

Nanopyramid structure for ultrathin c-Si tandem solar cells.  

PubMed

Recently, ultrathin crystalline silicon solar cells have gained tremendous interest because they are deemed to dramatically reduce material usage. However, the resulting conversion efficiency is still limited by the incomplete light absorption in such ultrathin devices. In this letter, we propose ultrathin a-Si/c-Si tandem solar cells with an efficient light trapping design, where a nanopyramid structure is introduced between the top and bottom cells. The superior light harvesting results in a 48% and 35% remarkable improvement of the short-circuit current density for the top and bottom cells, respectively. Meanwhile, the use of SiOx mixed-phase nanomaterial helps to provide the maximum light trapping without paying the price of reduced electrical performance, and conversion efficiencies of up to 13.3% have been achieved for the ultrathin tandem cell employing only 8 ?m of silicon, which is 29% higher than the result obtained for the planar cell. PMID:24730470

Li, Guijun; Li, He; Ho, Jacob Y L; Wong, Man; Kwok, Hoi Sing

2014-05-14

254

Trapped Particle Instability in Kinetic Stabilized Tandem Mirror  

NASA Astrophysics Data System (ADS)

The kinetic stabilizer tandem mirror (KSTM) devised by R. F. Post (J. Fus. Energy 2007) is an innovative concept devised to stabilize a symmetric tandem mirror machines using a concept devised by D. Ryutov (Proc. of Course and Workshop, Varenna, Italy, 1987) and empirically verified in the Gas Dynamic Trap (Ivanov, et. al. Trans. Fusion Technology 39, 127, 2001). The KSTM uses the momentum flux of unconfined particles that only sample the outer end regions of the mirror where there is very favorable field line curvature. Charged ion beams at relatively low energy are externally injected into the ends and reflected out from the ends. MHD stability with a power drain less than the fusion power production can be achieved. We examine the effect of fast growing trapped particle instability (Berk et. al. Sov J. Plasma Phys. 1983) on the overall stability. In this case stability is very sensitive to the electron connection between the stabilizer and end plug.

Berk, Herbert; Pratt, Jane

2009-11-01

255

Parametric instabilities during electron cyclotron heating of tandem mirrors  

NASA Technical Reports Server (NTRS)

Electron cyclotron resonance heating is one of the most commonly used methods of heating electrons in the plugs and in the thermal barriers of tandem mirrors. The intense coherent electromagnetic waves used for such heating are susceptible to parametric decay into other modes. Significant growth rates are found for the decay of either ordinary or extraordinary waves into two magnetized electron plasma waves. This and related effects may result in electron heating mechanisms rather different than those assumed in linear ray-tracing calculations. These results may help explain the unusual effects observed during heating of the Phaedrus tandem mirror device. In the general case, these instabilities may be strongly inhibited by density gradients.

Nicholson, D. R.

1984-01-01

256

Trail laying during tandem-running recruitment in the ant Temnothorax albipennis  

NASA Astrophysics Data System (ADS)

Tandem running is a recruitment strategy whereby one ant leads a single naïve nest mate to a resource. While tandem running progresses towards the goal, the leader ant and the follower ant maintain contact mainly by tactile signals. In this paper, we investigated whether they also deposit chemical signals on the ground during tandem running. We filmed tandem-running ants and analysed the position of the gasters of leaders and followers. Our results show that leader ants are more likely to press their gasters down to the substrate compared to follower ants, single ants and transporter ants. Forward tandem-run leaders (those moving towards a new nest site) performed such trail-marking procedures three times more often than reverse tandem leaders (those moving towards an old nest site). That leader ants marked the trails more often during forward tandem runs may suggest that it is more important to maintain the bond with the follower ant on forward tandem runs than on reverse tandem runs. Marked trails on the ground may serve as a safety line that improves both the efficiency of tandem runs and their completion rates.

Basari, Norasmah; Laird-Hopkins, Benita C.; Sendova-Franks, Ana B.; Franks, Nigel R.

2014-06-01

257

High efficiency inorganic/organic hybrid tandem solar cells.  

PubMed

Hybrid tandem solar cells comprising an inorganic bottom cell and an organic top cell have been designed and fabricated. The interlayer combination and thickness matching were optimized in order to increase the overall photovoltaic conversion efficiency. A maximum power conversion efficiency of 5.72% was achieved along with a V(oc) of 1.42 V, reaching as high as 92% of the sum of the subcell V(oc) values. PMID:22807214

Seo, Ji Hoon; Kim, Dong-Ho; Kwon, Se-Hun; Song, Myungkwan; Choi, Min-Seung; Ryu, Seung Yoon; Lee, Hyung Woo; Park, Yun Chang; Kwon, Jung-Dae; Nam, Kee-Seok; Jeong, Yongsoo; Kang, Jae-Wook; Kim, Chang Su

2012-08-28

258

Application of Tandem Ring-Closing Enyne Metathesis  

PubMed Central

A tandem ring-closing metathesis of a silaketal-based dienyne substrate proceeded efficiently to provide a bicyclic siloxane, which upon removal of the silicon tether afforded an (E,Z)-1,3-dienediol. Further manipulation of this key functional motif rendered synthesis of the entire C1-C19 linear skeleton of (—)-cochleamycin A, a late stage intermediate employed in the previous total synthesis of (+)-cochleamycin A by Roush and coworkers.

Mukherjee, Sumit; Lee, Daesung

2009-01-01

259

Finding All Sorting Tandem Duplication Random Loss Operations  

Microsoft Academic Search

A tandem duplication random loss (TDRL) operation duplicates a contiguous segment of genes, followed by the loss of one copy\\u000a of each of the duplicated genes. Although the importance of this operation is founded by several recent biological studies,\\u000a it has been investigated only rarely from a theoretical point of view. Of particular interest are sorting TDRLs which are\\u000a TDRLs

Matthias Bernt; Ming-chiang Chen; Daniel Merkle; Hung-lung Wang; Kun-mao Chao; Martin Middendorf

2009-01-01

260

Electrostatic plasma-confinement experiments in a tandem mirror system  

SciTech Connect

Results from the tandem mirror experiment are described. The configuration of axial density and potential profiles are created and sustained by neutral-beam injection and gas fueling. Plasma confinement in the center cell is shown to be improved by the end plugs by as much as a factor of 9. The electron temperature is higher than that achieved in our earlier 2XIIB single-cell mirror experiment.

Coensgen, F.H.; Anderson, C.A.; Casper, T.A.; Clauser, J.F.; Condit, W.C.; Correll, D.L.; Cummins, W.F.; Davis, J.C.; Drake, R.P.; Foote, J.H.; Futch, A.H.; Goodman, R.K.; Grubb, D.P.; Hallock, G.A.; Hornady, R.S.; Hunt, A.L.; Logan, B.G.; Munger, R.H.; Nexsen, W.E.; Simonen, T.C.; Slaughter, D.R.; Stallard, B.W.; Strand, O.T.

1980-04-28

261

De Novo Peptide Sequencing via Tandem Mass Spectrometry  

Microsoft Academic Search

Peptide sequencing via tandem mass spectrometry (MS\\/MS) is one of the most powerful tools in proteomics for identifying proteins. Because complete genome sequences are accumulat- ing rapidly, the recent trend in interpretation of MS\\/MS spectra has been database search. However, de novo MS\\/MS spectral interpretation remains an open problem typically involving manual interpretation by expert mass spectrometrists. We have developed

Vlado Dancík; Theresa A. Addona; Karl R. Clauser; James E. Vath; Pavel A. Pevzner

1999-01-01

262

A study of kynurenine fragmentation using electrospray tandem mass spectrometry  

Microsoft Academic Search

A combination of accurate mass measurement and tandem mass spectrometry (both product ion and precursor ion scans) have been\\u000a used to characterize the major fragment ions observed in the ESI mass spectrum of kynurenine. Kynurenine is a metabolite of\\u000a tryptophan found in the human lens and is thought to play a role in protecting the retina from UV-induced damage. Three

Santiago Vazquez; Roger J. W. Truscott; Richard A. J. O’Hair; Allan Weimann; Margaret M. Sheil

2001-01-01

263

Parameter Optimization Studies for a Tandem Mirror Neutron Source  

NASA Astrophysics Data System (ADS)

A basic plasma physics tandem mirror experiment is proposed to develop the potential uses of magnetic mirror confined plasmas for a neutron source. We consider parameter variations from the currently operating symmetric mirror plasma trap GDT in an attempt to optimize the neutron source intensity while minimizing the expense and complications of the system. The combined radial and axial plasma loss rates are analyzed and shown to yield an optimal operational point that minimizes the required auxiliary heating power.

Horton, W.; Fu, X. R.; Ivanov, A.; Beklemishev, A.

2010-12-01

264

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

265

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

266

Top down? protein characterization via tandem mass spectrometry  

Microsoft Academic Search

Technological and scientific advances over the past decade have enabled protein identification and characterizationstrategiestobedevelopedthatarebasedonsubjectingintactproteinionsandlargeprotein fragmentsdirectlytotandemmassspectrometry.Theseapproachesarereferredtocollectivelyas'topdown' tocontrastthemwith'bottomup'approacheswherebyproteinidentificationisbasedonmassspectrometric analysis of peptides derived from proteolytic digestion, usually with trypsin. A key step in enabling top down approaches has been the ability to assign tandem mass spectrometer product ion identities, which can be done either via high resolving power or through product ion charge

Gavin E. Reid; Scott A. McLuckey

2002-01-01

267

Facile synthesis of halogenated spiroketals via a tandem iodocyclization.  

PubMed

A strategy for the synthesis of spiroketal compounds through a tandem iodocyclization of 1-(2-ethynylphenyl)-4-hydroxybut-2-yn-1-one derivatives is presented. This reaction could proceed under very mild conditions in a short time and avoid the use of expensive and toxic metal catalysts. Moreover, the resulting halides can be further exploited by subsequent palladium-catalyzed coupling reactions, which act as the important intermediates for building other valuable compounds. PMID:24697268

Wang, Jia; Zhu, Hai-Tao; Li, Ying-Xiu; Wang, Li-Jing; Qiu, Yi-Feng; Qiu, Zi-Hang; Zhong, Mei-jin; Liu, Xue-Yuan; Liang, Yong-Min

2014-04-18

268

Operation of the Stony Brook tandem\\/linac accelerator system  

Microsoft Academic Search

The Stony Brook nuclear structure laboratory operates the first superconducting linac based on a lead-on-copper resonator technology. Heavy ions up to mass A&bartil;100 from the FN tandem Van de Graaff are boosted to energies of 5–10 MeV per nucleon for a variety of nuclear structure and reaction studies. We review the first 2 1\\/2 years of linac operating experience, with

John W. Noe´

1986-01-01

269

Flexible micromorph tandem aSi\\/muc-Si solar cells  

Microsoft Academic Search

The deposition of a stack of amorphous (a-Si:H) and microcrystalline (muc-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of muc-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the

T. Soederstroem; F.-J. Haug; V. Terrazzoni-Daudrix; C. Ballif

2010-01-01

270

A light weight tandem accelerator for neutron radiography  

Microsoft Academic Search

A light weight, compact 1.4 MV tandem accelerator is being constructed as part of a transportable neutron radiography system. A maximum current of 400 muA of 2.8 MeV deuterons on the beryllium target is expected to produce a primary neutron source of 8 × 1011 ns-1. The accelerator system uses multiple belts, a surface plasma negative deuterium ion source, a

T. D. Hayward; T. Armstrong; D. H. Epperson

1985-01-01

271

DNA polymerase ? generates tandem mutations in immunoglobulin variable regions.  

PubMed

Low-fidelity DNA polymerases introduce nucleotide substitutions in immunoglobulin variable regions during somatic hypermutation. Although DNA polymerase (pol) ? is the major low-fidelity polymerase, other DNA polymerases may also contribute. Existing data are contradictory as to whether pol ? is involved. We reasoned that the presence of pol ? may mask the contribution of pol ?, and therefore we generated mice deficient for pol ? and heterozygous for pol ?. The frequency and spectra of hypermutation was unaltered between Pol?(+/-) Pol?(-/-) and Pol?(+/+) Pol?(-/-) clones. However, there was a decrease in tandem double-base substitutions in Pol?(+/-) Pol?(-/-) cells compared with Pol?(+/+) Pol?(-/-) cells, suggesting that pol ? generates tandem mutations. Contiguous mutations are consistent with the biochemical property of pol ? to extend a mismatch with a second mutation. The presence of this unique signature implies that pol ? contributes to mutational synthesis in vivo. Additionally, data on tandem mutations from wild type, Pol?(+/-), Pol?(-/-), Ung(-/-), Msh2(-/-), Msh6(-/-), and Ung(-/-) Msh2(-/-) clones suggest that pol ? may function in the MSH2-MSH6 pathway. PMID:22615128

Saribasak, Huseyin; Maul, Robert W; Cao, Zheng; Yang, William W; Schenten, Dominik; Kracker, Sven; Gearhart, Patricia J

2012-06-01

272

Building and searching tandem mass spectral libraries for peptide identification.  

PubMed

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. PMID:21900153

Lam, Henry

2011-12-01

273

Cooperativity in Forced Unfolding of Tandem Spectrin Repeats  

PubMed Central

Force-driven conformational changes provide a broad basis for protein extensibility, and multidomain proteins broaden the possibilities further by allowing for a multiplicity of forcibly extended states. Red cell spectrin is prototypical in being an extensible, multidomain protein widely recognized for its contribution to erythrocyte flexibility. Atomic force microscopy has already shown that single repeats of various spectrin family proteins can be forced to unfold reversibly under extension. Recent structural data indicates, however, that the linker between triple-helical spectrin repeats is often a contiguous helix, thus raising questions as to what the linker contributes and what defines a domain mechanically. We have examined the extensible unfolding of red cell spectrins as monomeric constructs of just two, three, or four repeats from the actin-binding ends of both ?- and ?-chains, i.e., ?18–21 and ?1–4 or their subfragments. In addition to single repeat unfolding evident in sawtooth patterns peaked at relatively low forces (<50 pN at 1 nm/ms extension rates), tandem repeat unfolding is also demonstrated in ensemble-scale analyses of thousands of atomic force microscopy contacts. Evidence for extending two chains and loops is provided by force versus length scatterplots which also indicate that tandem repeat unfolding occurs at a significant frequency relative to single repeat unfolding. Cooperativity in forced unfolding of spectrin is also clearly demonstrated by a common force scale for the unfolding of both single and tandem repeats.

Law, Richard; Carl, Philippe; Harper, Sandy; Dalhaimer, Paul; Speicher, David W.; Discher, Dennis E.

2003-01-01

274

Accelerator-based diagnostics in tandem-mirror fusion experiments  

NASA Astrophysics Data System (ADS)

Several accelerator-based analysis techniques have proven useful in diagnosing plasma-edge and first-wall conditions in two tandem-mirror fusion experiments. This paper describes the various techniques and the use of solid-state probes in the tandem-mirror devices TMX and TMX-U in conjunction with subsequent analysis by Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), and secondary ion mass spectrometry (SIMS). RBS was used to measure the concentration of deposited impurities on solid-state probe samples. NRA, utilizing the D( 3He, ? )H reaction, gave quantitative data about deuterium retention levels in carbon samples exposed to the plasma. SIMS analysis produced near-surface depth profiles of implanted deuterium in exposed silicon samples. Taken together, these techniques provided detailed information about impurity levels, the flux and energy of particles striking the first-wall, and plasma-edge temperatures. This information has contributed towards an understanding of the confinement properties of tandem mirrors.

Bastasz, R.; Hsu, W. L.; Pontau, A. B.; Wilson, K. L.

1985-05-01

275

Highly efficient photocathodes for dye-sensitized tandem solar cells.  

PubMed

Thin-film dye-sensitized solar cells (DSCs) based on mesoporous semiconductor electrodes are low-cost alternatives to conventional silicon devices. High-efficiency DSCs typically operate as photoanodes (n-DSCs), where photocurrents result from dye-sensitized electron injection into n-type semiconductors. Dye-sensitized photocathodes (p-DSCs) operate in an inverse mode, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) with a theoretical efficiency limitation well beyond that of single-junction DSCs (ref. 4). Nevertheless, the efficiencies of such tandem pn-DSCs have so far been hampered by the poor performance of the available p-DSCs (refs 3, 5-15). Here we show for the first time that p-DSCs can convert absorbed photons to electrons with yields of up to 96%, resulting in a sevenfold increase in energy conversion efficiency compared with previously reported photocathodes. The donor-acceptor dyes, studied as photocathodic sensitizers, comprise a variable-length oligothiophene bridge, which provides control over the spatial separation of the photogenerated charge carriers. As a result, charge recombination is decelerated by several orders of magnitude and tandem pn-DSCs can be constructed that exceed the efficiency of their individual components. PMID:19946281

Nattestad, A; Mozer, A J; Fischer, M K R; Cheng, Y-B; Mishra, A; Bäuerle, P; Bach, U

2010-01-01

276

Alternative splicing regulation at tandem 3? splice sites  

PubMed Central

Alternative splicing (AS) constitutes a major mechanism creating protein diversity in humans. Previous bioinformatics studies based on expressed sequence tag and mRNA data have identified many AS events that are conserved between humans and mice. Of these events, ?25% are related to alternative choices of 3? and 5? splice sites. Surprisingly, half of all these events involve 3? splice sites that are exactly 3 nt apart. These tandem 3? splice sites result from the presence of the NAGNAG motif at the acceptor splice site, recently reported to be widely spread in the human genome. Although the NAGNAG motif is common in human genes, only a small subset of sites with this motif is confirmed to be involved in AS. We examined the NAGNAG motifs and observed specific features such as high sequence conservation of the motif, high conservation of ?30 bp at the intronic regions flanking the 3? splice site and overabundance of cis-regulatory elements, which are characteristic of alternatively spliced tandem acceptor sites and can distinguish them from the constitutive sites in which the proximal NAG splice site is selected. Our findings imply that AS at tandem splice sites and constitutive splicing of the distal NAG are highly regulated.

Akerman, Martin; Mandel-Gutfreund, Yael

2006-01-01

277

Fabrication and characterization of polymer tandem solar cells  

NASA Astrophysics Data System (ADS)

Polymer tandem solar cells were fabricated and characterized. Copolymer poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly((4,4-octyldithieno(3,2-b:20,30-d)silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl) (PSBTBT) were used as p-type semiconductors, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was used as an n-type semiconductor. The open circuit voltage was improved up to 0.69 V by using the tandem structure of P3HT:PCBM and PSBTBT:PCBM layers as compared with those of P3HT:PCBM and PSBTBT:PCBM single cell of 0.53 V and 0.10 V, respectively. Absorption of the tandem cell was in the range of 400 to 800 nm, which corresponded to a sum of those in P3HT:PCBM and PSBTBT:PCBM single cells.

Maruhashi, Haruto; Suzuki, Atsushi; Akiyama, Tsuyoshi; Oku, Takeo

2013-04-01

278

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.

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

1986-06-01

279

Flexible micromorph tandem a-Si/?c-Si solar cells  

NASA Astrophysics Data System (ADS)

The deposition of a stack of amorphous (a-Si:H) and microcrystalline (?c-Si:H) tandem thin film silicon solar cells (micromorph) requires at least twice the time used for a single junction a-Si:H cell. However, micromorph devices have a higher potential efficiency, thanks to the broader absorption spectrum of ?c-Si:H material. High efficiencies can only be achieved by mitigating the nanocracks in the ?c-Si:H cell and the light-induced degradation of the a-Si:H cell. As a result, ?c-Si:H cell has to grow on a smooth substrate with large periodicity (>1 ?m) and the a-Si:H cell on sharp pyramids with smaller feature size (~350 nm) to strongly scatter the light in the weak absorption spectra of a-Si:H material. The asymmetric intermediate reflector introduced in this work uncouples the growth and light scattering issues of the tandem micromorph solar cells. The stabilized efficiency of the tandem n-i-p/n-i-p micromorph is increased by a relative 15% compared to a cell without AIR and 32% in relative compared to an a-Si:H single junction solar cells. The overall process (T<200 °C) is kept compatible with low cost plastic substrates. The best stabilized efficiency of a cell deposited on polyethylene-naphthalate plastic substrate is 9.8% after 1000 h of light soaking at Voc, 1 sun, and 50 °C.

Söderström, T.; Haug, F.-J.; Terrazzoni-Daudrix, V.; Ballif, C.

2010-01-01

280

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

SciTech Connect

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/sup 3/, with a resultant neutron wall loading of 0.5 MW/m/sup 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 ..cap alpha..-particles from the plasma.

Damm, C.C.; Doggett, J.N.; Bulmer, R.H.

1980-12-18

281

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

282

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

283

The mechanism and effective connecting architecture for tandem organic light-emitting devices  

NASA Astrophysics Data System (ADS)

The concept of tandem organic light-emitting devices (OLEDs) provides a pathway for developing highly stable and efficient OLEDs. The connecting structure that bridges adjacent light-emitting units, substantially affects the device performance of tandem OLEDs. In this letter, we introduce an effective connecting structure in which an ultrathin middle metal layer is sandwiched between efficient electron- and hole-injection layers for the tandem OLEDs, which in essence, avoids the use of reactive metals during fabrication. Two-unit tandem OLEDs with such connecting structure exhibit less than double the driving voltage, yet more than double the efficiency, more saturated emission color, and longer operational lifetime compared to those of single-unit devices. A model based on a hypothesis of energy level pinning effect has been proposed as the mechanism of the connecting structure in the tandem devices. This model is also consistent with the results obtained from the photovoltaic effect measurements in tandem OLEDs.

Chen, Chieh-Wei; Wu, Elbert Hsing-En; Chu, Chih-Wei; Wu, Chung-Chih; Yang, Yang

2005-10-01

284

Reactor issues for tandem mirrors operating in the negative-potential mode  

SciTech Connect

During 1985, interest has been revived at LLNL in tandem mirrors operating in the negative-potential mode. The negative tandem is formed by combining ECRH-sustained hot electron end cell plasmas with pumping mechanisms to remove trapped ions from the end cells. No sloshing ions are required. The resulting negative potential in the end cells confines the central cell electrons. The requirement of charge neutrality causes the ambipolar potential of the central cell to become negative relative to the end wall (hence, the name ''negative' tandem mirror), thereby providing central cell ion confinement. This potential distribution is the exact inverse of the axial distribution for the conventional (positive) tandem mirror without thermal barriers. In the negative tandem mirror, central cell electrons are confined electrostatically, end cell electrons are confined magnetically, and ions are confined electrostatically everywhere. In this report, we briefly assess the reactor issues pertinent to the operation of the tandem mirror in the negative mode. 7 refs., 5 figs.

Perkins, L.J.; Campbell, R.B.

1985-12-02

285

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

286

LipidBlast in silico tandem mass spectrometry database for lipid identification.  

PubMed

Current tandem mass spectral libraries for lipid annotations in metabolomics are limited in size and diversity. We provide a freely available computer-generated tandem mass spectral library of 212,516 spectra covering 119,200 compounds from 26 lipid compound classes, including phospholipids, glycerolipids, bacterial lipoglycans and plant glycolipids. We show platform independence by using tandem mass spectra from 40 different mass spectrometer types including low-resolution and high-resolution instruments. PMID:23817071

Kind, Tobias; Liu, Kwang-Hyeon; Lee, Do Yup; DeFelice, Brian; Meissen, John K; Fiehn, Oliver

2013-08-01

287

Sample stacking capillary electrophoretic microdevice for highly sensitive mini Y short tandem repeat genotyping.  

PubMed

Lab-on-a-chip provides an ideal platform for short tandem repeat (STR) genotyping due to its intrinsic low sample consumption, rapid analysis, and high-throughput capability. One of the challenges, however, in the forensic human identification on the microdevice is the detection sensitivity derived from the nanoliter volume sample handling. To overcome such a sensitivity issue, here we developed a sample stacking CE microdevice for mini Y STR genotyping. The mini Y STR includes redesigned primer sequences to generate smaller-sized PCR amplicons to enhance the PCR efficiency and the success rate for a low copy number and degraded DNA. The mini Y STR amplicons occupied in the 5- and 10-mm stacking microchannels are preconcentrated efficiently in a defined narrow region through the optimized sample stacking CE scheme, resulting in more than tenfold improved fluorescence peak intensities compared with that of a conventional cross-injection microcapillary electrophoresis method. Such signal enhancement allows us to successfully analyze the Y STR typing with only 25?pg of male genomic DNA, with high background of female genomic DNA, and with highly degraded male genomic DNA. The combination of the mini Y STR system with the novel sample stacking CE microdevice provides the highly sensitive Y STR typing on a chip, making it promising to perform high-performance on-site forensic human identification. PMID:20715129

Chen, Yuchao; Choi, Jong Young; Choi, Seok Jin; Seo, Tae Seok

2010-09-01

288

Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells; January 28, 2010 -- January 31, 2011.  

National Technical Information Service (NTIS)

Final subcontract report for PV Incubator project 'Novel R2R Manufacturable Photonic-Enhanced Thin Film Solar Cells.' The goal of this program was to produce tandem Si cells using photonic bandgap enhancement technology developed at ISU and Lightwave Powe...

D. Slafer V. Dalal

2012-01-01

289

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

290

Tandem repeat copy-number variation in protein-coding regions of human genes  

PubMed Central

Background Tandem repeat variation in protein-coding regions will alter protein length and may introduce frameshifts. Tandem repeat variants are associated with variation in pathogenicity in bacteria and with human disease. We characterized tandem repeat polymorphism in human proteins, using the UniGene database, and tested whether these were associated with host defense roles. Results Protein-coding tandem repeat copy-number polymorphisms were detected in 249 tandem repeats found in 218 UniGene clusters; observed length differences ranged from 2 to 144 nucleotides, with unit copy lengths ranging from 2 to 57. This corresponded to 1.59% (218/13,749) of proteins investigated carrying detectable polymorphisms in the copy-number of protein-coding tandem repeats. We found no evidence that tandem repeat copy-number polymorphism was significantly elevated in defense-response proteins (p = 0.882). An association with the Gene Ontology term 'protein-binding' remained significant after covariate adjustment and correction for multiple testing. Combining this analysis with previous experimental evaluations of tandem repeat polymorphism, we estimate the approximate mean frequency of tandem repeat polymorphisms in human proteins to be 6%. Because 13.9% of the polymorphisms were not a multiple of three nucleotides, up to 1% of proteins may contain frameshifting tandem repeat polymorphisms. Conclusion Around 1 in 20 human proteins are likely to contain tandem repeat copy-number polymorphisms within coding regions. Such polymorphisms are not more frequent among defense-response proteins; their prevalence among protein-binding proteins may reflect lower selective constraints on their structural modification. The impact of frameshifting and longer copy-number variants on protein function and disease merits further investigation.

O'Dushlaine, Colm T; Edwards, Richard J; Park, Stephen D; Shields, Denis C

2005-01-01

291

A tandem cross-metathesis/semipinacol rearrangement reaction.  

PubMed

An efficient and (E)-selective synthesis of a 6-alkylidenebicyclo[3.2.1]octan-8-one has been developed. The key step is a tandem cross-metathesis/semipinacol rearrangement reaction, wherein the Hoveyda-Grubbs II catalyst, or more likely a derivative thereof, serves as the Lewis acid for the rearrangement. Despite the fact that both the starting alkene and the cross-metathesis product are viable rearrangement substrates, only the latter rearranges, suggesting that the Lewis acidic species is generated only after the cross-metathesis reaction is complete. PMID:22540517

Plummer, Christopher W; Soheili, Arash; Leighton, James L

2012-05-18

292

Tandem Friedel-Crafts annulation to novel perylene analogues.  

PubMed

Novel dialkyloxy- and dihydroxyoctahydroperylenes are regioselectively available via a new tandem Friedel-Crafts alkylation of tetrahydronaphthalene precursors followed by oxidative aromatization. Heating of 5-alkyloxy-1-tetralol with p-toluenesulfonic acid in sulfolane gave the corresponding octahydroperylenes in moderate yields. Studies with Lewis acids and tetralin-1,5-diol in acetonitrile at room temperature provided the 4,10-dihydroxy analogue cleanly, albeit in reduced yields. Examples of these new series of perylene analogues were partially oxidized to the corresponding contiguously aromatic, anthracene core products or fully aromatized to 3,9-dialkyloxyperylenes in good yields. PMID:18630879

Penick, Mark A; Mahindaratne, Mathew P D; Gutierrez, Robert D; Smith, Terrill D; Tiekink, Edward R T; Negrete, George R

2008-08-15

293

Tandem isomerization/telomerization of long chain dienes  

PubMed Central

The first example of a tandem reaction involving double-bond migration in combination with telomerization is reported. Homogeneous and heterogeneous Ru catalysts were employed as isomerization catalysts, and telomerization was realized using a homogeneous Pd(0) precursor complex with a N-heterocyclic carbene (IMes) ligand. Overall conversions approaching 60% were achieved with the best selectivity to telomerization products of 91% attained at 11% conversion. Conversion was markedly higher in the presence of longer-chain alcohol (1-butanol) as the nucleophile (telogen).

Torrente-Murciano, Laura; Nielsen, David J.; Cavell, Kingsley J.; Lapkin, Alexei A.

2014-01-01

294

The MLL partial tandem duplication in acute myeloid leukaemia.  

PubMed

Mixed lineage leukaemia gene-partial tandem duplications (MLL-PTD) characterise acute myeloid leukaemia (AML) with trisomy 11 and AML with a normal karyotype. MLL-PTD confer a worse prognosis with shortened overall and event free survival in childhood and adult AML. In spite of these clinical observations, the leukaemogenic mechanism has, so far, not been determined. This review summarises clinical studies on MLL-PTD positive AML and recent experimental findings on the putative leukaemogenic role of MLL-PTD. PMID:16965385

Basecke, Jorg; Whelan, Jarrett T; Griesinger, Frank; Bertrand, Fred E

2006-11-01

295

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

296

Tandem photoaffinity labeling-bioorthogonal conjugation in medicinal chemistry.  

PubMed

Photoaffinity labeling has a longstanding history as a powerful biochemical technique. However, photoaffinity labeling has significantly evolved over the past decade principally due to its coupling with bioorthogonal/click chemistry reactions. This review aims to highlight tandem photoaffinity labeling-bioorthogonal conjugation as a chemical approach in medicinal chemistry and chemical biology. In particular, recent examples of using this strategy for affinity-based protein profiling (AfBPP), drug target identification, binding ensemble profiling, studying endogenous biological molecules, and imaging applications will be presented. Additionally, recent advances in the development of 'all-in-one' compact moieties possessing a photoreactive group and clickable handle will be discussed. PMID:23026086

Lapinsky, David J

2012-11-01

297

Numerical model of tandem organic light-emitting diodes based on a transition metal oxide interconnector layer  

NASA Astrophysics Data System (ADS)

By utilizing a two-step process to express the charge generation and separation mechanism of the transition metal oxides (TMOs) interconnector layer, a numerical model was proposed for tandem organic light emitting diodes (OLEDs) with a TMOs thin film as the interconnector layer. This model is valid not only for an n-type TMOs interconnector layer, but also for a p-type TMOs interconnector layer. Based on this model, the influences of different carrier injection barriers at the interface of the electrode/organic layer on the charge generation ability of interconnector layers were studied. In addition, the distribution characteristics of carrier concentration, electric field intensity and potential in the device under different carrier injection barriers were studied. The results show that when keeping one carrier injection barrier as a constant while increasing another carrier injection barrier, carriers injected into the device were gradually decreased, the carrier generation ability of the interconnector layer was gradually reduced, the electric field intensity at the interface of the organic/electrode was gradually enhanced, and the electric field distribution became nearly linear: the voltage drops in two light units gradually became the same. Meanwhile, the carrier injection ability decreased as another carrier injection barrier increased. The simulation results agree with the experimental data. The obtained results can provide us with a deep understanding of the work mechanism of TMOs-based tandem OLEDs.

Feiping, Lu; Yingquan, Peng; Yongzhong, Xing

2014-04-01

298

Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system  

DOEpatents

This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

Dziendziel, Randolph J. (Middle Grove, NY); DePoy, David Moore (Clifton Park, NY); Baldasaro, Paul Francis (Clifton Park, NY)

2007-01-23

299

Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system  

DOEpatents

This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

Dziendziel, Randolph J. (Middle Grove, NY); Baldasaro, Paul F. (Clifton Park, NY); DePoy, David M. (Clifton Park, NY)

2010-09-07

300

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system  

DOEpatents

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength {lambda}{sub IF} approximately equal to the bandgap wavelength {lambda}{sub g} of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5{lambda}{sub IF} to {lambda}{sub IF} and reflect from {lambda}{sub IF} to about 2{lambda}{sub IF}; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5{lambda}{sub IF}. 10 figs.

Brown, E.J.; Baldasaro, P.F.; Dziendziel, R.J.

1997-12-23

301

Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system  

DOEpatents

A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength .lambda..sub.IF approximately equal to the bandgap wavelength .lambda..sub.g of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5.lambda..sub.IF to .lambda..sub.IF and reflect from .lambda..sub.IF to about 2.lambda..sub.IF ; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5.lambda..sub.IF.

Brown, Edward J. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY); Dziendziel, Randolph J. (Middlegrove, NY)

1997-01-01

302

Nuclear factor kappaB signaling in atherogenesis  

Microsoft Academic Search

Atherosclerosis is an inflammatory disease, characterized by the accumulation of macrophage-derived foam cells in the vessel wall and accompanied by the production of a wide range of chemokines, cytokines, and growth factors. These factors regulate the turnover and differentiation of immigrating and resident cells, eventually influencing plaque development. One of the key regulators of inflammation is the transcription factor nuclear

M. P. J. de Winther; E. Kanters; G. Kraal; M. H. Hofker

2005-01-01

303

A dynamic programming approach to de novo peptide sequencing via tandem mass spectrometry  

Microsoft Academic Search

Tandem mass spectrometry fragments a large number of molecules of the same peptide se- quence into charged molecules of pre é x and sufé x peptide subsequences and then measures mass\\/charge ratios of these ions. The de novo peptide sequencing problem is to reconstruct the peptide sequence from a given tandem mass spectral data of k ions. By implicitly trans-

Ting Chen; Ming-Yang Kao; Matthew Tepel; John Rush; George M. Church

2000-01-01

304

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

305

Unequal Crossing Over Is the Principal Pathway of Homologous Recombination in Tandem Duplications of Escherichia coli  

Microsoft Academic Search

Homologous recombination between direct DNA repeats in tandem duplications usually leads to their dissociation. An even number of crossovers between two copies of a duplication should lead to the formation of diploid segregants, i.e., to the preservation of the duplication. However, in studies of the genotype of diploid segregants in heterozygous tandem duplications of Escherichia coli, it was shown that

V. V. Prokop’ev; V. V. Sukhodolets

2005-01-01

306

Expansions and Contractions in a Tandem Repeat Induced by Double-Strand Break Repair  

Microsoft Academic Search

Repair of a double-strand break (DSB) in yeast can induce very frequent expansions and contractions in a tandem array of 375-bp repeats. These results strongly suggest that DSB repair can be a major source of amplification of tandemly repeated sequences. Most of the DSB repair events are not associated with crossover. Rearrangements appear in 50% of these repaired recipient molecules.

FREDERIC PAQUES; WAI-YING LEUNG; JAMES E. HABER

1998-01-01

307

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

PubMed Central

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.

2013-01-01

308

Negotiation of Meaning and Corrective Feedback in Japanese/English eTandem  

ERIC Educational Resources Information Center

This paper presents a comparative analysis of corrective feedback provided by participants in an eTandem interaction between university students in Japan and Australia who were learning each other's language. Corrective feedback provided to tandem partners during interaction via text-based Synchronous Computer Mediated Communication (SCMC) is…

Bower, Jack; Kawaguchi, Satomi

2011-01-01

309

XSTREAM: A practical algorithm for identification and architecture modeling of tandem repeats in protein sequences  

Microsoft Academic Search

Background: Biological sequence repeats arranged in tandem patterns are widespread in DNA and proteins. While many software tools have been designed to detect DNA tandem repeats (TRs), useful algorithms for identifying protein TRs with varied levels of degeneracy are still needed. Results: To address limitations of current repeat identification methods, and to provide an efficient and flexible algorithm for the

Aaron M. Newman; James B. Cooper

2007-01-01

310

Monolingual and crosslingual comparison of tandem features derived from articulatory and phone MLPS  

Microsoft Academic Search

The features derived from posteriors of a multilayer perceptron (MLP), known as tandem features, have proven to be very effective for automatic speech recognition. Most tandem features to date have relied on MLPs trained for phone classification. We recently showed on a relatively small data set that MLPs trained for articulatory feature classification can be equally effective. In this paper,

O. Cetin; M. Magimai-Doss; K. Livescu; A. Kantor; S. King; C. Bartels; J. Frankel

2007-01-01

311

An Articulatory Feature-Based Tandem Approach and Factored Observation Modeling  

Microsoft Academic Search

The so-called tandem approach, where the posteriors of a multilayer perceptron (MLP) classifier are used as features in an automatic speech recognition (ASR) system has proven to be a very effective method. Most tandem approaches up to date have relied on MLPs trained for phone classification, and appended the posterior features to some standard feature hidden Markov model (HMM). In

O. Cetin; A. Kantor; S. King; C. Bartels; M. Magimai-Doss; J. Frankel; K. Livescu

2007-01-01

312

Call blocking probabilities in a traffic-groomed tandem optical network  

Microsoft Academic Search

In this paper, we consider an optical network consisting of N nodes arranged in tandem. We assume traffic grooming, which permits multiple sub-rate traffic streams to be carried on the same wavelength. This optical network is modeled by a tandem queueing network of multi- rate Erlang loss nodes with simultaneous resource possession, with a view to calculating call blocking probabilities.

Alicia Nicki Washington; Harry G. Perros

2004-01-01

313

Toward a heuristic optimum design of rolling schedules for tandem cold rolling mills  

Microsoft Academic Search

Scheduling for tandem cold mills refers to the determination of inter-stand gauges, tensions and speeds of a specified product. Optimal schedules should result in maximized throughput and minimized operating cost. This paper presents a genetic algorithm based optimization procedure for the scheduling of tandem cold rolling mills. The optimization procedure initiates searching from a logical staring point — an empirical

D. D. Wang; A. K. Tieu; F. G. de Boer; B. Ma; W. Y. D. Yuen

2000-01-01

314

Charge state determination of peptide tandem mass spectra using support vector machine (SVM)  

Microsoft Academic Search

A single mass spectrometry experiment could produce hundreds of thousands of tandem mass spectra. Several search engines have been developed to interpret tandem mass spectra. All search engines need to determine the masses of peptide ions from their mass\\/charge ratios. Unfortunately, mass spectrometers do not detect the charges of ions. A current strategy is to search candidate peptides multiple times,

An-Min Zou; Jin-Hong Shi; Jiarui Ding; Fang-Xiang Wu

2010-01-01

315

Charge state determination of peptide tandem mass spectra using support vector machine (SVM)  

Microsoft Academic Search

A single mass spectrometry experiment could produce hundreds of thousands of tandem mass spectra. Several search engines have been developed to interpret tandem mass spectra. All search engines need to determine the masses of peptide ions from mass\\/charge ratios of ions. Unfortunately, mass spectrometers do not detect the charges of ions. A current strategy is to search candidate peptides multiply

An-min Zou; Jiarui Ding; Jin-hong Shi; Fang-xiang Wu

2008-01-01

316

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

317

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

318

A Transposable Element can Drive the Concerted Evolution of Tandemly Repetitious DNA  

Microsoft Academic Search

Recombination and conversion have been proposed to drive the concerted evolution of tandemly repeated DNA sequences. However, specific correction events within the repeated genes of multicellular organisms have not been observed directly, so their nature has remained speculative. We investigated whether the excision of transposable P elements from tandemly repeated sequences would induce unequal gene conversion. Genetically marked elements located

Dianne Thompson-Stewart; Gary H. Karpen; Allan C. Spradling

1994-01-01

319

Tandem photovoltaic cells formed in single fullerene films by impurity doping  

NASA Astrophysics Data System (ADS)

Tandem photovoltaic cells were formed in single fullerene films by doping with molybdenum oxide and cesium carbonate. A heavily doped n+p+-homojunction acted as an ohmic interlayer between the two pn-homojunction cells. The observed photovoltaic properties of the tandem cell were shown to be consistent with the energy band diagram mapped using a Kelvin probe.

Ishiyama, Norihiro; Kubo, Masayuki; Kaji, Toshihiko; Hiramoto, Masahiro

2012-12-01

320

Differential length measurement using low coherence coupled tandem interferometry  

NASA Astrophysics Data System (ADS)

This paper presents the use of low coherence coupled tandem interferometry to measure the differential length of two independent Fabry-Perot (F-P) type microcavities. The two discrete F-P type microcavities are formed between the cleaved end of a fibre and a reflective surface, which could for example, be a pressure sensing membrane or any other component of a transducing element. The technique is an all-optical fibre based sensing configuration in which the sensing cavities are at widely separated locations in an environment where strong temperature gradients may exist. The sensing system is based on two sequential cavities arranged in tandem. The lengths of the cavities are probed by a temperature stabilised fibre based Michelson interferometer operating with a broadband light source. One arm of the probing Michelson interferometer is scanned using a piezo fibre stretcher resulting in an optical path length difference (OPD) between the two arms. The optical interconnecting leads from the probing Michelson interferometer to the two F-P locations are not an active part of the sensor configuration and therefore this configuration is largely insensitive to temperature and strain effects on these interconnecting leads. It is only the probing Michelson interferometer which has to be temperature stabilised. This arrangement allows the F-P measurement cavities to be separated by distances in the range of tens of meters.

Smith, Martin D.; MacPherson, William N.; Maier, Robert R. J.

2013-05-01

321

The First Tandem, All-exciplex-based WOLED  

PubMed Central

Exploiting our recently developed bilayer interface methodology, together with a new wide energy-gap, low LUMO acceptor (A) and the designated donor (D) layers, we succeeded in fabricating an exciplex-based organic light-emitting diode (OLED) systematically tuned from blue to red. Further optimization rendered a record-high blue exciplex OLED with ?ext of 8%. We then constructed a device structure configured by two parallel blend layers of mCP/PO-T2T and DTAF/PO-T2T, generating blue and yellow exciplex emission, respectively. The resulting device demonstrates for the first time a tandem, all-exciplex-based white-light OLED (WOLED) with excellent efficiencies ?ext: 11.6%, ?c: 27.7?cd A?1, and ?p: 15.8?ml W?1 with CIE(0.29, 0.35) and CRI 70.6 that are nearly independent of EL intensity. The tandem architecture and blend-layer D/A (1:1) configuration are two key elements that fully utilize the exciplex delay fluorescence, providing a paragon for the use of low-cost, abundant organic compounds en route to commercial WOLEDs.

Hung, Wen-Yi; Fang, Guan-Cheng; Lin, Shih-Wei; Cheng, Shuo-Hsien; Wong, Ken-Tsung; Kuo, Ting-Yi; Chou, Pi-Tai

2014-01-01

322

Alpha-driven mironoinstability in tandem mirror plasma  

SciTech Connect

Alpha particles born at deuterium-tritium (D-T) fusion are mirror confined in the tandem mirror with a loss-cone-type distribution in the velocity space. The anisotropy created is susceptible to microinstabilities and the objective of this work is to study possible instabilities that can be driven by the alpha loss-cone. The low-frequency (at the order of the ion cyclotron frequency) wave spectrum is examined to seek the waves that can be destabilized by the alphas. A marginal stability boundary in ion density-temperature space is found. The central cell of the tandem mirror is modeled by an infinite, long plasm cylinder with azimuthal symmetry. The plasma consists of both deuteron and triton as fuel ions and is assumed to be cold since the ion velocity is much smaller than that of the alpha. This model also considers a sharp boundary plasma, with a vacuum region separating it from the conducting wall. To examine reactor implication, the authors have calculated the stability boundary for the cases of the MARS and MINIMARS parameters. The operating regime for both cases is found to be unstable. this could be a key problem for reactor operation and deserves more study. 4 refs., 2 figs.

Ho, S.K.; Miley, G.H.; Smith, G.R.; Nevins, W.M.

1986-01-01

323

Functional divergence in tandemly duplicated Arabidopsis thaliana trypsin inhibitor genes.  

PubMed Central

In multigene families, variation among loci and alleles can contribute to trait evolution. We explored patterns of functional and genetic variation in six duplicated Arabidopsis thaliana trypsin inhibitor (ATTI) loci. We demonstrate significant variation in constitutive and herbivore-induced transcription among ATTI loci that show, on average, 65% sequence divergence. Significant variation in ATTI expression was also found between two molecularly defined haplotype classes. Population genetic analyses for 17 accessions of A. thaliana showed that six ATTI loci arranged in tandem within 10 kb varied 10-fold in nucleotide diversity, from 0.0009 to 0.0110, and identified a minimum of six recombination events throughout the tandem array. We observed a significant peak in nucleotide and indel polymorphism spanning ATTI loci in the interior of the array, due primarily to divergence between the two haplotype classes. Significant deviation from the neutral equilibrium model for individual genes was interpreted within the context of intergene linkage disequilibrium and correlated patterns of functional differentiation. In contrast to the outcrosser Arabidopsis lyrata for which recombination is observed even within ATTI loci, our data suggest that response to selection was slowed in the inbreeding, annual A. thaliana because of interference among functionally divergent ATTI loci.

Clauss, M J; Mitchell-Olds, T

2004-01-01

324

Cloud parallel processing of tandem mass spectrometry based proteomics data.  

PubMed

Data analysis in mass spectrometry based proteomics struggles to keep pace with the advances in instrumentation and the increasing rate of data acquisition. Analyzing this data involves multiple steps requiring diverse software, using different algorithms and data formats. Speed and performance of the mass spectral search engines are continuously improving, although not necessarily as needed to face the challenges of acquired big data. Improving and parallelizing the search algorithms is one possibility; data decomposition presents another, simpler strategy for introducing parallelism. We describe a general method for parallelizing identification of tandem mass spectra using data decomposition that keeps the search engine intact and wraps the parallelization around it. We introduce two algorithms for decomposing mzXML files and recomposing resulting pepXML files. This makes the approach applicable to different search engines, including those relying on sequence databases and those searching spectral libraries. We use cloud computing to deliver the computational power and scientific workflow engines to interface and automate the different processing steps. We show how to leverage these technologies to achieve faster data analysis in proteomics and present three scientific workflows for parallel database as well as spectral library search using our data decomposition programs, X!Tandem and SpectraST. PMID:22916831

Mohammed, Yassene; Mostovenko, Ekaterina; Henneman, Alex A; Marissen, Rob J; Deelder, André M; Palmblad, Magnus

2012-10-01

325

The First Tandem, All-exciplex-based WOLED.  

PubMed

Exploiting our recently developed bilayer interface methodology, together with a new wide energy-gap, low LUMO acceptor (A) and the designated donor (D) layers, we succeeded in fabricating an exciplex-based organic light-emitting diode (OLED) systematically tuned from blue to red. Further optimization rendered a record-high blue exciplex OLED with ?ext of 8%. We then constructed a device structure configured by two parallel blend layers of mCP/PO-T2T and DTAF/PO-T2T, generating blue and yellow exciplex emission, respectively. The resulting device demonstrates for the first time a tandem, all-exciplex-based white-light OLED (WOLED) with excellent efficiencies ?ext: 11.6%, ?c: 27.7?cd A(-1), and ?p: 15.8?ml W(-1) with CIE(0.29, 0.35) and CRI 70.6 that are nearly independent of EL intensity. The tandem architecture and blend-layer D/A (1:1) configuration are two key elements that fully utilize the exciplex delay fluorescence, providing a paragon for the use of low-cost, abundant organic compounds en route to commercial WOLEDs. PMID:24895098

Hung, Wen-Yi; Fang, Guan-Cheng; Lin, Shih-Wei; Cheng, Shuo-Hsien; Wong, Ken-Tsung; Kuo, Ting-Yi; Chou, Pi-Tai

2014-01-01

326

36Cl exposure dating with a 3-MV tandem  

NASA Astrophysics Data System (ADS)

36Cl AMS measurements at natural isotopic concentrations have yet been performed only at tandem accelerators with 5 MV terminal voltage or beyond. We have developed a method to detect 36Cl at natural terrestrial isotopic concentrations with a 3-MV system, operated above specifications at 3.5 MV. An effective separation was obtained with an optimized split-anode ionization chamber design (adopted from the ETH/PSI Zurich AMS group), providing a suppression factor of up to 30,000 for the interfering isobar 36S. Despite the good separation, a relatively high sulfur output from the ion source ( 36S -/ 35Cl - ? 4 × 10 -10 for samples prepared from chemically pure reagents), and a possibly cross contamination resulted in a background corresponding to 36Cl/Cl ? 3 × 10 -14. The method was applied to samples containing between 10 5 and 10 6 atoms 36Cl/g rock from sites in Italy and Iran, which were already investigated by other laboratories for surface exposure dating. The 36Cl/Cl ratios in the range from 2 × 10 -13 to 5 × 10 -12 show a generally good agreement with the previous results. These first measurements demonstrate that also 3-MV tandems, constituting the majority of dedicated AMS facilities, are capable of 36Cl exposure dating, which is presently the domain of larger facilities.

Steier, Peter; Forstner, Oliver; Golser, Robin; Kutschera, Walter; Martschini, Martin; Merchel, Silke; Orlowski, Tobias; Priller, Alfred; Vockenhuber, Christof; Wallner, Anton

2010-04-01

327

Comparison of tandem-in-space and tandem-in-time mass spectrometry in gas chromatography determination of pesticides: Application to simple and complex food samples  

Microsoft Academic Search

Gas chromatography coupled to tandem mass spectrometry (GC–MS\\/MS) is one of the most powerful techniques in pesticide residue analysis. MS\\/MS can be conceived in two ways: tandem in space (e.g. triple quadrupole, QqQ) or in time (e.g. ion trap, IT). QqQ and IT are commonly interfaced to GC; however, there has not been any direct comparison between them in pesticide

A. Garrido Frenich; P. Plaza-Bolaños; J. L. Martínez Vidal

2008-01-01

328

A p53-dependent promoter associated with polymorphic tandem repeats controls the expression of a viral transcript encoding clustered microRNAs  

PubMed Central

The tumor suppressor protein p53 plays a role in cellular responses to cancer-initiating events by regulating progress through the cell cycle. Several recent studies have shown that p53 transactivates expression of the members of the proapoptotic microRNA-34 family, which are underexpressed in several cancers. We demonstrate here that the latency-associated cluster of microRNAs (miRNA) encoded by an oncogenic herpesvirus, gallid herpesvirus 2 (GaHV-2), is a direct target of p53. Robust transcriptional activity was induced in three avian cell lines by a sequence mapping 600 base pairs (bp) upstream of the cluster of miRNAs. We found transcription start sites for the pri-miRNA transcript at the 3? end of this transcription-inducing sequence. The promoter has no consensus core promoter element, but is organized into a variable number of tandem repeats of 60-bp harboring p53-responsive elements (RE). The minimal functional construct consists of two tandem repeats. Mutagenesis to change the sequence of the p53 RE abolished transcriptional activity, whereas p53 induction enhanced mature miRNA expression. The identification of a viral miRNA promoter regulated by p53 is biologically significant, because all avirulent GaHV-2 strains described to date lack the corresponding regulatory sequence, whereas all virulent, very virulent, and hypervirulent strains possess at least two tandem repeats harboring the p53 RE.

Stik, Gregoire; Laurent, Sylvie; Coupeau, Damien; Coutaud, Baptiste; Dambrine, Ginette; Rasschaert, Denis; Muylkens, Benoit

2010-01-01

329

Role of EBNA-1 in arresting replication forks at the Epstein-Barr virus oriP family of tandem repeats.  

PubMed Central

The 20-member family of 30-bp tandem repeats located within the oriP region of Epstein-Barr virus (EBV) can act as a transcriptional enhancer in the presence of EBV nuclear antigen 1 (EBNA-1). A replication fork barrier and a termination site of plasmid replication in human B cells is also found within or near the EBV tandem repeats. Within each tandem repeat is a consensus binding sequence for the EBNA-1 protein that is required for extrachromosomal maintenance of oriP-containing plasmids. To investigate the factors that contribute to the arrest of replication forks and termination in the region of the family of repeats, we have used an in vitro replication system in which replication of EBV recombinant plasmids is initiated from the simian virus 40 (SV40) DNA replication origin in the presence of SV40 T antigen and soluble extracts prepared from human cells. The system can support bidirectional replication, initiating from the SV40 DNA origin with termination occurring in a region opposite the origin. Using two-dimensional agarose gel electrophoresis, we observed a barrier to replication forks in the presence of EBNA-1 in the region of the EBV repeats. Termination occurs at or near the tandem repeats in a manner similar to that observed in vivo (T.A. Gahn and C.L. Schildkraut, Cell 58:527-535, 1989). Reducing the number of repeats from 20 to 6 had little effect on the strength of the replication fork barrier. In the absence of EBNA-1, replication forks also arrested at the EBV repeats, but at a much lower efficiency. The addition of competitor DNA containing the EBV family of repeats can almost completely abolish the replication barrier produced in the presence of EBNA-1. Images

Dhar, V; Schildkraut, C L

1991-01-01

330

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

2013-01-01

331

Focused tandem shock waves in water and their potential application in cancer treatment  

NASA Astrophysics Data System (ADS)

The generator of two focused successive (tandem) shock waves (FTSW) in water produced by underwater multichannel electrical discharges at two composite electrodes, with a time delay between the first and second shock waves of 10 s, was developed. It produces, at the focus, a strong shock wave with a peak positive pressure of up to 80 MPa, followed by a tensile wave with a peak negative pressure of up to MPa, thus generating at the focus a large amount of cavitation. Biological effects of FTSW were demonstrated in vitro on hemolysis of erythrocytes and cell viability of human acute lymphoblastic leukemia cells as well as on tumor growth delay ex vivo and in vivo experiments performed with B16 melanoma, T-lymphoma, and R5-28 sarcoma cell lines. It was demonstrated in vivo that FTSW can enhance antitumor effects of chemotherapeutic drugs, such as cisplatin, most likely due to increased permeability of the membrane of cancer cells induced by FTSW. Synergetic cytotoxicity of FTSW with sonosensitive porphyrin-based drug Photosan on tumor growth was observed, possibly due to the cavitation-induced sonodynamic effect of FTSW.

Lukes, P.; Sunka, P.; Hoffer, P.; Stelmashuk, V.; Pouckova, P.; Zadinova, M.; Zeman, J.; Dibdiak, L.; Kolarova, H.; Tomankova, K.; Binder, S.; Benes, J.

2014-01-01

332

Neutral Beam Injection Experiments and Related Behavior of Neutral Particles in the GAMMA 10 Tandem Mirror  

SciTech Connect

Results of neutral beam injection (NBI) experiments in the GAMMA 10 tandem mirror plasmas are presented together with the neutral particle behavior observed in the experiments. A hydrogen neural beam was injected into the hot-ion-mode plasmas by using the injector installed in the central-cell for the plasma heating and fueling. High-energy ions produced by NBI were observed and its energy distribution was measured for the first time with a neutral particle analyzer installed in the central-cell. The temporal and spatial behavior of hydrogen was observed with axially aligned H{sub {alpha}} detectors installed from the central midplane to anchor-cell. Enhancement of hydrogen recycling due to the beam injection and the cause of the observed decrease in plasma diamagnetism are discussed. The Monte-Carlo code DEGAS for neutral transport simulation was applied to the GAMMA 10 central-cell and a 3-dimensional simulation was performed in the NBI experiment. Localization of neutral particle during the beam injection is investigated based on the simulation and it was found that the increased recycling due to the beam injection was dominant near the injection port.

Nakashima, Y. [Plasma Research Center, University of Tsukuba (Japan); Watanabe, K. [Plasma Research Center, University of Tsukuba (Japan); Higashizono, Y. [Plasma Research Center, University of Tsukuba (Japan); Ohki, T. [Plasma Research Center, University of Tsukuba (Japan); Ogita, T. [Plasma Research Center, University of Tsukuba (Japan); Shoji, M. [National Institute for Fusion Science(Japan); Kobayashi, S. [Institute of Advanced Energy, Kyoto University (Japan); Islam, M.K. [Plasma Research Center, University of Tsukuba (Japan); Kubota, Y. [Plasma Research Center, University of Tsukuba (Japan); Yoshikawa, M. [Plasma Research Center, University of Tsukuba (Japan); Kobayashi, T. [Plasma Research Center, University of Tsukuba (Japan); Yamada, M. [Plasma Research Center, University of Tsukuba (Japan); Murakami, R. [Plasma Research Center, University of Tsukuba (Japan); Cho, T. [Plasma Research Center, University of Tsukuba (Japan)

2005-01-15

333

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

334

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

2013-09-01

335

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

2013-03-01

336

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

337

Quantification of peramivir in dog plasma by liquid chromatography/tandem mass spectrometry employing precolumn derivatization.  

PubMed

Peramivir is a novel influenza neuraminidase inhibitor used for anti-influenza. In this article, a novel method was developed to determine peramivir in dog plasma using a derivatization treatment step to increase the retention time and enhance the signal intensity. The sample preparation consisted of a protein precipitation extraction followed by derivatization with 10M hydrochloric acid-methanol (10:90, v/v) and determined by liquid chromatography coupled with tandem mass spectrometry. The selected reaction monitoring mode of the positive ion was performed and the precursor to the product ion transitions of m/z 343?284 and m/z 299?152 were used to measure the derivative of peramivir and Ro 64-0802 (internal standard, an active metabolite of oseltamivir). The chromatographic separation was achieved using a ZORBAX RX-C8 (2.0mm×150mm×5?m) analytical column with an isocratic mobile phase composed of acetonitrile-water-formic acid (30:70:0.1, v/v/v, 0.2mL/min). The method was linear over a concentration range of 0.25-250ng/mL. The average intra-day/inter-day precision values were 4.04-8.17% and 3.02-7.08%, respectively, while the average accuracy value was 93.99-106.48%. This method has been successfully applied to the preclinical dog research of peramivir following intragastric administration. PMID:24280376

Li, Xin; Li, Ying; Wang, Juan; Wang, Lili; Zhong, Wu; Ruan, Jinxiu; Zhang, Zhenqing

2014-01-01

338

APE1 incision activity at abasic sites in tandem repeat sequences.  

PubMed

Repetitive DNA sequences, such as those present in microsatellites and minisatellites, telomeres, and trinucleotide repeats (linked to fragile X syndrome, Huntington disease, etc.), account for nearly 30% of the human genome. These domains exhibit enhanced susceptibility to oxidative attack to yield base modifications, strand breaks, and abasic sites; have a propensity to adopt non-canonical DNA forms modulated by the positions of the lesions; and, when not properly processed, can contribute to genome instability that underlies aging and disease development. Knowledge on the repair efficiencies of DNA damage within such repetitive sequences is therefore crucial for understanding the impact of such domains on genomic integrity. In the present study, using strategically designed oligonucleotide substrates, we determined the ability of human apurinic/apyrimidinic endonuclease 1 (APE1) to cleave at apurinic/apyrimidinic (AP) sites in a collection of tandem DNA repeat landscapes involving telomeric and CAG/CTG repeat sequences. Our studies reveal the differential influence of domain sequence, conformation, and AP site location/relative positioning on the efficiency of APE1 binding and strand incision. Intriguingly, our data demonstrate that APE1 endonuclease efficiency correlates with the thermodynamic stability of the DNA substrate. We discuss how these results have both predictive and mechanistic consequences for understanding the success and failure of repair protein activity associated with such oxidatively sensitive, conformationally plastic/dynamic repetitive DNA domains. PMID:24703901

Li, Mengxia; Völker, Jens; Breslauer, Kenneth J; Wilson, David M

2014-05-29

339

Doping control analysis of metamfepramone and two major metabolites using liquid chromatography-tandem mass spectrometry.  

PubMed

The sympathomimetic agent metamfepramone (2-dimethylamino-1-phenylpropan-1-one, dimethylpropion) is widely used for the treatment of the common cold or hypotonic conditions. Due to its stimulating properties and its rapid metabolism resulting in major degradation products such as methylpseudoephedrine and methcathinone, it has been considered relevant for doping controls by the World Anti-Doping Agency (WADA). The rapid degradation of the active drug complicates the detection of metamfepramone itself but the metabolites methylpseudoephedrine and methcathinone can be monitored, and the finding of the latter in particular allows the inference of a metamfepramone administration. In order to improve sports drug testing procedures, metamfepramone, methylpseudoephedrine and methcathinone were characterized using electrospray ionization-high resolution/high accuracy mass spectrometry, and a method employing liquid chromatography/tandem mass spectrometry was established that allowed the analysis of these three analytes by direct injection of 2 microL of urine specimens. The assay was validated with regard to specificity, lower limits of detection (2-10 ng mL(-1)), intraday and interday precision (3-17%) and ion suppression/enhancement effects. The developed procedure has been used to verify or falsify suspicious signals observed in routine screening procedures based on gas chromatography/mass spectrometry and yielded an adverse analytical finding concerning a metamfepramone administration in an authentic doping control sample. Although the active drug was not detected, the indicative metabolites methylpseudoephedrine and methcathinone were considered sufficient to infer the application of the prohibited drug. PMID:19661559

Thevis, Mario; Sigmund, Gerd; Thomas, Andreas; Gougoulidis, Vassilios; Rodchenkov, Grigory; Schänzer, Wilhelm

2009-01-01

340

Recognition of an intra-chain tandem 14-3-3 binding site within PKCepsilon.  

PubMed

The phosphoserine/threonine binding protein 14-3-3 stimulates the catalytic activity of protein kinase C-epsilon (PKCepsilon) by engaging two tandem phosphoserine-containing motifs located between the PKCepsilon regulatory and catalytic domains (V3 region). Interaction between 14-3-3 and this region of PKCepsilon is essential for the completion of cytokinesis. Here, we report the crystal structure of 14-3-3zeta bound to a synthetic diphosphorylated PKCepsilon V3 region revealing how a consensus 14-3-3 site and a divergent 14-3-3 site cooperate to bind to 14-3-3 and so activate PKCepsilon. Thermodynamic data show a markedly enhanced binding affinity for two-site phosphopeptides over single-site 14-3-3 binding motifs and identifies Ser 368 as a gatekeeper phosphorylation site in this physiologically relevant 14-3-3 ligand. This dual-site intra-chain recognition has implications for other 14-3-3 targets, which seem to have only a single 14-3-3 motif, as other lower affinity and cryptic 14-3-3 gatekeeper sites might exist. PMID:19662078

Kostelecky, Brenda; Saurin, Adrian T; Purkiss, Andrew; Parker, Peter J; McDonald, Neil Q

2009-09-01

341

Evaluation of the Consensus of Four Peptide Identification Algorithms for Tandem Mass Spectrometry Based Proteomics  

PubMed Central

The availability of different scoring schemes and filter settings of protein database search algorithms has greatly expanded the number of search methods for identifying candidate peptides from MS/MS spectra. We have previously shown that consensus-based methods that combine three search algorithms yield higher sensitivity and specificity compared to the use of a single search engine (individual method). We hypothesized that union of four search engines (Sequest, Mascot, X!Tandem and Phenyx) can further enhance sensitivity and specificity. ROC plots were generated to measure the sensitivity and specificity of 5460 consensus methods derived from the same dataset. We found that Mascot outperformed individual methods for sensitivity and specificity, while Phenyx performed the worst. The union consensus methods generally produced much higher sensitivity, while the intersection consensus methods gave much higher specificity. The union methods from four search algorithms modestly improved sensitivity, but not specificity, compared to union methods that used three search engines. This suggests that a strategy based on specific combination of search algorithms, instead of merely ‘as many search engines as possible’, may be key strategy for success with peptide identification. Lastly, we provide strategies for optimizing sensitivity or specificity of peptide identification in MS/MS spectra for different user-specific conditions.

Dagda, Ruben K.; Sultana, Tamanna; Lyons-Weiler, James

2010-01-01

342

Protein Identification False Discovery Rates for Very Large Proteomics Data Sets Generated by Tandem Mass Spectrometry*  

PubMed Central

Comprehensive characterization of a proteome is a fundamental goal in proteomics. To achieve saturation coverage of a proteome or specific subproteome via tandem mass spectrometric identification of tryptic protein sample digests, proteomics data sets are growing dramatically in size and heterogeneity. The trend toward very large integrated data sets poses so far unsolved challenges to control the uncertainty of protein identifications going beyond well established confidence measures for peptide-spectrum matches. We present MAYU, a novel strategy that reliably estimates false discovery rates for protein identifications in large scale data sets. We validated and applied MAYU using various large proteomics data sets. The data show that the size of the data set has an important and previously underestimated impact on the reliability of protein identifications. We particularly found that protein false discovery rates are significantly elevated compared with those of peptide-spectrum matches. The function provided by MAYU is critical to control the quality of proteome data repositories and thereby to enhance any study relying on these data sources. The MAYU software is available as standalone software and also integrated into the Trans-Proteomic Pipeline.

Reiter, Lukas; Claassen, Manfred; Schrimpf, Sabine P.; Jovanovic, Marko; Schmidt, Alexander; Buhmann, Joachim M.; Hengartner, Michael O.; Aebersold, Ruedi

2009-01-01

343

Fully automated screening of veterinary drugs in milk by turbulent flow chromatography and tandem mass spectrometry  

PubMed Central

There is an increasing interest in screening methods for quick and sensitive analysis of various classes of veterinary drugs with limited sample pre-treatment. Turbulent flow chromatography in combination with tandem mass spectrometry has been applied for the first time as an efficient screening method in routine analysis of milk samples. Eight veterinary drugs, belonging to seven different classes were selected for this study. After developing and optimising the method, parameters such as linearity, repeatability, matrix effects and carry-over were studied. The screening method was then tested in the routine analysis of 12 raw milk samples. Even without internal standards, the linearity of the method was found to be good in the concentration range of 50 to 500 µg/L. Regarding repeatability, RSDs below 12% were obtained for all analytes, with only a few exceptions. The limits of detection were between 0.1 and 5.2 µg/L, far below the maximum residue levels for milk set by the EU regulations. While matrix effects—ion suppression or enhancement—are obtained for all the analytes the method has proved to be useful for screening purposes because of its sensitivity, linearity and repeatability. Furthermore, when performing the routine analysis of the raw milk samples, no false positive or negative results were obtained.

Stolker, Alida A. M.; Peters, Ruud J. B.; Zuiderent, Richard; DiBussolo, Joseph M.

2010-01-01

344

Malignant Solitary Fibrous Tumor of Tandem Lesions in the Skull and Spine  

PubMed Central

A Solitary Fibrous Tumor (Sft) Is A Rare Neoplasm Originated From The Pleura, But They Can Occur In A Variety Of Extrathoracic Regions. Although Many Cases Of Primary Sft Have Been Reported, There Are Extremely Rare Repots To Date Of A Malignant Sft In The Spine Or Skull. A 54-year-woman Visited Our Hospital Due To Low Back Pain And Both Leg Radiating Pain. Several Imaging Studies Including Magnetic Resonance Imaging And Computed Tomography Revealed Expansive Enhanced Lesions In The Occipital Bone, T8, S1-2, And Ilium, With Neural Tissue Compression. We Performed Surgical Resection Of The Tumor In Each Site, And Postoperative Radiosurgery And Chemotherapy Were Performed. However, After Six Months, Tumors Were Recurred And Metastasized In Multiple Regions Including Whole Spine And Lung. The Authors Report Here The First Case Of Patient With Malignant Sft Of Tandem Lesions In The Various Bony Structures, Including Skull, Thoracic Spine, And Sacral Spine, With A Rapid Recurrence And Metastasis. Although Malignant Sft Is Extremely Rare, It Should Be Considered In The Differential Diagnosis And Carful Follow-up Is Needed.

Son, Seong; Jeong, Dong-Hae; Yoo, Chan Jong

2013-01-01

345

Malignant solitary fibrous tumor of tandem lesions in the skull and spine.  

PubMed

A Solitary Fibrous Tumor (Sft) Is A Rare Neoplasm Originated From The Pleura, But They Can Occur In A Variety Of Extrathoracic Regions. Although Many Cases Of Primary Sft Have Been Reported, There Are Extremely Rare Repots To Date Of A Malignant Sft In The Spine Or Skull. A 54-year-woman Visited Our Hospital Due To Low Back Pain And Both Leg Radiating Pain. Several Imaging Studies Including Magnetic Resonance Imaging And Computed Tomography Revealed Expansive Enhanced Lesions In The Occipital Bone, T8, S1-2, And Ilium, With Neural Tissue Compression. We Performed Surgical Resection Of The Tumor In Each Site, And Postoperative Radiosurgery And Chemotherapy Were Performed. However, After Six Months, Tumors Were Recurred And Metastasized In Multiple Regions Including Whole Spine And Lung. The Authors Report Here The First Case Of Patient With Malignant Sft Of Tandem Lesions In The Various Bony Structures, Including Skull, Thoracic Spine, And Sacral Spine, With A Rapid Recurrence And Metastasis. Although Malignant Sft Is Extremely Rare, It Should Be Considered In The Differential Diagnosis And Carful Follow-up Is Needed. PMID:24278657

Son, Seong; Lee, Sang-Gu; Jeong, Dong-Hae; Yoo, Chan Jong

2013-09-01

346

Duplication of CaMV 35S Promoter Sequences Creates a Strong Enhancer for Plant Genes  

Microsoft Academic Search

A variant of the cauliflower mosaic virus 35S promoter with transcriptional activity approximately tenfold higher than that of the natural promoter was constructed by tandem duplication of 250 base pairs of upstream sequences. The duplicated region also acted as a strong enhancer of heterologous promoters, increasing the activity of an adjacent and divergently transcribed transferred DNA gene several hundredfold, and

Robert Kay; Amy Chan; Mark Daly; Joan McPherson

1987-01-01

347

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

348

Structural Basis of Actin Filament Nucleation by Tandem W Domains  

PubMed Central

SUMMARY Spontaneous nucleation of actin is very inefficient in cells. To overcome this barrier, cells have evolved a set of actin filament nucleators to promote rapid nucleation and polymerization in response to specific stimuli. However, the molecular mechanism of actin nucleation remains poorly understood. This is hindered largely by the fact that actin nucleus, once formed, rapidly polymerizes into filament, thus making it impossible to capture stable multisubunit actin nucleus. Here, we report an effective double-mutant strategy to stabilize actin nucleus by preventing further polymerization. Employing this strategy, we solved the crystal structure of AMPPNP-actin in complex with the first two tandem W domains of Cordon-bleu (Cobl), a potent actin filament nucleator. Further sequence comparison and functional studies suggest that the nucleation mechanism of Cobl is probably shared by the p53 cofactor JMY, but not Spire. Moreover, the double-mutant strategy opens the way for atomic mechanistic study of actin nucleation and polymerization.

Chen, Xiaorui; Ni, Fengyun; Tian, Xia; Kondrashkina, Elena; Wang, Qinghua; Ma, Jianpeng

2013-01-01

349

Profiling oligosaccharidurias by electrospray tandem mass spectrometry: quantifying reducing oligosaccharides.  

PubMed

A method to semiquantify urinary oligosaccharides from patients suffering from oligosaccharidurias is presented. 1-Phenyl-3-methyl-5-pyrazolone has been used to derivatize urinary oligosaccharides prior to analysis by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Disease-specific oligosaccharides were identified for several oligosaccharidurias, including GM1 gangliosidosis, GM2 gangliosidosis, sialic acid storage disease, sialidase/neuraminidase deficiency, galactosialidosis, I-cell disease, fucosidosis, Pompe and Gaucher diseases, and alpha-mannosidosis. The oligosaccharides were referenced against the internal standard, methyl lactose, to produce ratios for comparison with control samples. Elevations in specific urinary oligosaccharides were indicative of lysosomal disease and the defective catabolic enzyme. This method has been adapted to enable assay of large sample numbers and could readily be extended to other oligosaccharidurias and to monitor oligosaccharide levels in patients receiving treatment. It also has immediate potential for incorporation into a newborn screening program. PMID:16111643

Ramsay, Steven L; Meikle, Peter J; Hopwood, John J; Clements, Peter R

2005-10-01

350

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

351

Structural Characterization of Carbohydrates by Fourier Transform Tandem Mass Spectrometry  

PubMed Central

Fourier transform tandem mass spectrometry (MS/MS) provides high mass accuracy, high sensitivity, and analytical versatility and has therefore emerged as an indispensable tool for structural elucidation of biomolecules. Glycosylation is one of the most common posttranslational modifications, occurring in ~50% of proteins. However, due to the structural diversity of carbohydrates, arising from non-template driven biosynthesis, achievement of detailed structural insight is highly challenging. This review briefly discusses carbohydrate sample preparation and ionization methods, and highlights recent developments in alternative high-resolution MS/MS strategies, including infrared multiphoton dissociation (IRMPD), electron capture dissociation (ECD), and electron detachment dissociation (EDD), for carbohydrates with a focus on glycans and proteoglycans from mammalian glycoproteins.

Zhou, Wen; Hakansson, Kristina

2012-01-01

352

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

353

Orbit averaged radial buildup code for tandem mirror geometry  

NASA Astrophysics Data System (ADS)

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.

1981-01-01

354

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

355

Tandem adaptation with a common design in Escherichia coli chemotaxis.  

PubMed

We analyze a model for motor-level adaptation in Escherichia coli based upon the premise that clockwise (CW) and counter-clockwise (CCW) states have different preferred numbers of FliM subunits. We show that this model provides a simple mechanism for the recently observed motor-level adaptation, and it also explains the long-lasting puzzle on the thresholds observed when tethered cells are used to monitor responses to temporal ramps. We note that the motor-level adaptation has the same negative-feedback network design as the upstream receptor-level adaptation, and the tandem architecture of one control circuit followed by the other mitigates the effects of cell-to-cell variation and broadens the range of stimuli over which cells optimally respond. PMID:22922485

Tu, Yuhai; Berg, Howard C

2012-11-01

356

Tandem repeat analysis for surveillance of human Salmonella Typhimurium infections.  

PubMed

In Denmark, as part of the national laboratory-based surveillance system of human enteric infections, all Salmonella enterica serotype Typhimurium isolates are currently subtyped by using phage typing, antimicrobial resistance profiles, and pulsed-field gel electrophoresis (PFGE). We evaluated the value of real-time typing that uses multiple-locus variable-number tandem-repeats analysis (MLVA) of S. Typhimurium to detect possible outbreaks. Because only a few subtypes identified by PFGE and phage typing account for most infections, we included MLVA typing in the routine surveillance in a 2-year period beginning December 2003. The 1,019 typed isolates were separated into 148 PFGE types and 373 MLVA types. Several possible outbreaks were detected and confirmed. MLVA was particularly valuable for discriminating within the most common phage types. MLVA was superior to PFGE for both surveillance and outbreak investigations of S. Typhimurium. PMID:17552091

Torpdahl, Mia; Sørensen, Gitte; Lindstedt, Bjørn-Arne; Nielsen, Eva Møller

2007-03-01

357

Two-terminal, thin film, tandem solar cells  

SciTech Connect

This patent describes a polycrystalline, tandem, photovoltaic transducer, comprising: (a) an upper cell having a bandgap of about 1.7 eV and comprising a heterojunction of n-type CdSe and p-type ZnTe, the junction being formed by depositing the ZnTe on the CdSe at low temperatures below about 350/sup 0/C; (b) a lower cell electrically connected to the upper cell, having a bandgap of about 1.0 eV, and comprising a thin film heterojunction between a graded ternary I-III-VI/sub 2/ semiconductor and a thin film II-VI semiconductor window layer.

Stanbery, B.J.

1987-07-14

358

Sequencing of oligourea foldamers by tandem mass spectrometry.  

PubMed

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. PMID:23400773

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

2013-03-01

359

Tandem demodulation lock-in amplifier based on digital signal processor for dual-modulated spectroscopy  

NASA Astrophysics Data System (ADS)

Dual-modulated spectroscopy is one of the most powerful methods in the measurement of modulation spectroscopy. Here we develop a tandem lock-in amplifier (LIA) based on digital signal processor to implement a novel algorithm of tandem demodulation. The theoretical analysis of demodulation algorithm is presented, and the implementation of this tandem LIA is described in detail. Compared to the traditional demodulating way with two LIAs in cascade, this tandem LIA eliminates the extra quantization error of redundant analog-to-digital and digital-to-analog conversions and removes the limitation to the time constant in the commercial LIA, hence lowers the requirement of frequency ratio in dual-modulated spectroscopy. The applications are given as examples in the photoreflectance (PR) measurements of GaAs (100) thin film and GaSb bulk material, respectively, at the different optical energy regions. The experimental results indicate that this tandem is well capable of PR spectra measurement with good PR lineshapes and reasonable signal noise ratio. A brief comparison of GaAs PR results between tandem LIA and two LIAs is made to prove the efficiency and advantages of the tandem LIA.

Qin, Jianhuan; Huang, Zhiming; Ge, Yujian; Hou, Yun; Chu, Junhao

2009-03-01

360

DNA Damage by Ionizing Radiation: Tandem Double Lesions by Charged Particles  

NASA Technical Reports Server (NTRS)

Oxidative damages by ionizing radiation are the source of radiation-induced carcinogenesis, damage to the central nervous system, lowering of the immune response, as well as other radiation-induced damages to human health. Monte Carlo track simulations and kinetic modeling of radiation damages to the DNA employ available molecular and cellular data to simulate the biological effect of high and low LET radiation io the DNA. While the simulations predict single and double strand breaks and base damages, so far all complex lesions are the result of stochastic coincidence from independent processes. Tandem double lesions have not yet been taken into account. Unlike the standard double lesions that are produced by two separate attacks by charged particles or radicals, tandem double lesions are produced by one single attack. The standard double lesions dominate at the high dosage regime. On the other hand, tandem double lesions do not depend on stochastic coincidences and become important at the low dosage regime of particular interest to NASA. Tandem double lesions by hydroxyl radical attack of guanine in isolated DNA have been reported at a dosage of radiation as low as 10 Gy. The formation of two tandem base lesions was found to be linear with the applied doses, a characteristic of tandem lesions. However, tandem double lesions from attack by a charged particle have not been reported.

Huo, Winifred M.; Chaban, Galina M.; Wang, Dunyou; Dateo, Christopher E.

2005-01-01

361

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

362

Detection of dispersed short tandem repeats using reversible jump Markov chain Monte Carlo  

PubMed Central

Tandem repeats occur frequently in biological sequences. They are important for studying genome evolution and human disease. A number of methods have been designed to detect a single tandem repeat in a sliding window. In this article, we focus on the case that an unknown number of tandem repeat segments of the same pattern are dispersively distributed in a sequence. We construct a probabilistic generative model for the tandem repeats, where the sequence pattern is represented by a motif matrix. A Bayesian approach is adopted to compute this model. Markov chain Monte Carlo (MCMC) algorithms are used to explore the posterior distribution as an effort to infer both the motif matrix of tandem repeats and the location of repeat segments. Reversible jump Markov chain Monte Carlo (RJMCMC) algorithms are used to address the transdimensional model selection problem raised by the variable number of repeat segments. Experiments on both synthetic data and real data show that this new approach is powerful in detecting dispersed short tandem repeats. As far as we know, it is the first work to adopt RJMCMC algorithms in the detection of tandem repeats.

Liang, Tong; Fan, Xiaodan; Li, Qiwei; Li, Shuo-yen R.

2012-01-01

363

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

364

Assay for Glycosaminoglycans by Tandem Mass Spectrometry and its Applications  

PubMed Central

Glycosaminoglycans (GAGs) are distributed in the whole body and play a variety of important physiological roles associated with inflammation, growth, coagulation, fibrinolysis, lipolysis, and cell-matrix biology. Accumulation of undegraded GAGs in lysosomes gives rise to a distinct clinical syndrome, mucopolysaccharidoses. Measurement of each specific GAG in a variety of specimens is urgently required to understand GAG interaction with other molecules, physiological status of patients, and prognosis and pathogenesis of the disease. We established a highly sensitive and accurate tandem mass spectrometry (LC-MS/MS) method for measurements of disaccharides derived from four specific GAGs [dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), and chondroitin sulfate (CS)]. Disaccharides were produced by specific enzyme digestion of each GAG, and quantified by negative ion mode of multiple reaction monitoring. Subclasses of HS and GAGs with identical molecular weights can be separated using a Hypercarbcolumn (2.0 mm×50 mm, 5 ?m) with an aectonitrile gradient in ammonium acetate (pH 11.0). We also developed a GAG assay by RapidFire with tandem mass spectrometry (RF-MS/MS). The RF system consists of an integrated solid phase extraction robot that binds and de-salts samples from assay plates and directly injects them into a MS/MS detector, reducing sample processing time to ten seconds. RF-MS/MS consequently yields much faster throughput than conventional LC-MS/MS-based methods. However, the RF system does not have a chromatographic step, and therefore, cannot distinguish GAGs that have identical molecular weights. Both methods can be applied to analysis of dried blood spots, blood, and urine specimens. In this article, we compare the assay methods for GAGs and describe their potential applications.

Tomatsu, Shunji; Shimada, Tsutomu; Mason, Robert W; Kelly, Joan; LaMarr, William A; Yasuda, Eriko; Shibata, Yuniko; Futatsumori, Hideyuki; Montano, Adriana M; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Tadao

2014-01-01

365

Detection of tandem duplications and implications for linkage analysis.  

PubMed Central

The first demonstration of an autosomal dominant human disease caused by segmental trisomy came in 1991 for Charcot-Marie-Tooth disease type 1A (CMT1A). For this disorder, the segmental trisomy is due to a large tandem duplication of 1.5 Mb of DNA located on chromosome 17p11.2-p12. The search for the CMT1A disease gene was misdirected and impeded because some chromosome 17 genetic markers that are linked to CMT1A lie within this duplication. To better understand how such a duplication might affect genetic analyses in the context of disease gene mapping, we studied the effects of marker duplication on transmission probabilities of marker alleles, on linkage analysis of an autosomal dominant disease, and on tests of linkage homogeneity. We demonstrate that the undetected presence of a duplication distorts transmission ratios, hampers fine localization of the disease gene, and increases false evidence of linkage heterogeneity. In addition, we devised a likelihood-based method for detecting the presence of a tandemly duplicated marker when one is suspected. We tested our methods through computer simulations and on CMT1A pedigrees genotyped at several chromosome 17 markers. On the simulated data, our method detected 96% of duplicated markers (with a false-positive rate of 5%). On the CMT1A data our method successfully identified two of three loci that are duplicated (with no false positives). This method could be used to identify duplicated markers in other regions of the genome and could be used to delineate the extent of duplications similar to that involved in CMT1A.

Matise, T. C.; Chakravarti, A.; Patel, P. I.; Lupski, J. R.; Nelis, E.; Timmerman, V.; Van Broeckhoven, C.; Weeks, D. E.

1994-01-01

366

Tandem gene arrays in Trypanosoma brucei: Comparative phylogenomic analysis of duplicate sequence variation  

PubMed Central

Background The genome sequence of the protistan parasite Trypanosoma brucei contains many tandem gene arrays. Gene duplicates are created through tandem duplication and are expressed through polycistronic transcription, suggesting that the primary purpose of long, tandem arrays is to increase gene dosage in an environment where individual gene promoters are absent. This report presents the first account of the tandem gene arrays in the T. brucei genome, employing several related genome sequences to establish how variation is created and removed. Results A systematic survey of tandem gene arrays showed that substantial sequence variation existed across the genome; variation from different regions of an array often produced inconsistent phylogenetic affinities. Phylogenetic relationships of gene duplicates were consistent with concerted evolution being a widespread homogenising force. However, tandem duplicates were not usually identical; therefore, any homogenising effect was coincident with divergence among duplicates. Allelic gene conversion was detected using various criteria and was apparently able to both remove and introduce sequence variation. Tandem arrays containing structural heterogeneity demonstrated how sequence homogenisation and differentiation can occur within a single locus. Conclusion The use of multiple genome sequences in a comparative analysis of tandem gene arrays identified substantial sequence variation among gene duplicates. The distribution of sequence variation is determined by a dynamic balance of conservative and innovative evolutionary forces. Gene trees from various species showed that intraspecific duplicates evolve in concert, perhaps through frequent gene conversion, although this does not prevent sequence divergence, especially where structural heterogeneity physically separates a duplicate from its neighbours. In describing dynamics of sequence variation that have consequences beyond gene dosage, this survey provides a basis for uncovering the hidden functionality within tandem gene arrays in trypanosomatids.

Jackson, Andrew P

2007-01-01

367

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

368

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

369

Optical properties of ytterbium-doped tandem-pumped fiber oscillator  

NASA Astrophysics Data System (ADS)

With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.

Hao, Jin-Ping; Yan, Ping; Xiao, Qi-Rong; Li, Dan; Gong, Ma-Li

2014-01-01

370

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

371

Chemical Engineering Challenges in Driving Thermochemical Hydrogen Processes with the Tandem Mirror Reactor.  

National Technical Information Service (NTIS)

The Tandem Mirror Reactor is described and compared with Tokamaks, both from a basic physics viewpoint and from the suitability of the respective reactor for synfuel production. Differences and similarities between the TMR as an electricity producer or a ...

T. R. Galloway R. W. Werner

1980-01-01

372

Measuring complete isotopomer distribution of aspartate using gas chromatography/tandem mass spectrometry.  

PubMed

We have developed a simple and accurate method for determining the complete positional isotopomer distribution of aspartate carbon atoms by gas chromatography/tandem mass spectrometry for (13)C-metabolic flux analysis. First, we screened tandem mass spectrometry (MS) spectra of the tert-butyldimethylsilyl (TBDMS) derivative of aspartate for daughter fragments with the necessary carbon atom fragmentations to fully resolve all 16 isotopomers of aspartate. Tandem MS scanning parameters were optimized for each daughter fragment, and the accuracy of tandem MS measurements were evaluated. We selected five accurate fragments that provided a redundant set of 47 labeling measurements to quantify the complete isotopomer distribution of aspartate by least-squares regression. The validity of the approach was demonstrated using six (13)C-labeled aspartate standards and natural aspartate. PMID:22510303

Choi, Jungik; Grossbach, Matthew T; Antoniewicz, Maciek R

2012-05-15

373

Modeling study for developing CdZnTe(CdSe)/CIGS tandem solar cells  

NASA Astrophysics Data System (ADS)

Based on Crosslight APSYS, single junction ZnTe/CdSe, CdZnTe/CdSe and CIGS/CdS solar cells as well as CdZnTe(CdSe)/CIGS tandem cells are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves are presented. The results are discussed with respect to the interface recombination velocity and the related material defect trap states for ZnTe/CdSe single junction solar cells and the top TCO layer affinity for tandem cells. The projected efficiency obtained is 28% for one of the modeled twoterminal tandem cells. The modeling results give possible clues for developing CdZnTe(CdSe)/CIGS tandem solar cells with increased efficiency.

Xiao, Y. G.; Li, Z. Q.; Lestrade, M.; Li, Z. M. S.

2010-08-01

374

Annual report of the Tandem Accelerator Center, University of Tsukuba. April 1, 1992 - March 31, 1993.  

National Technical Information Service (NTIS)

This annual report includes the research activities and the technical developments carried out at the Tandem Accelerator Center in University of Tsukuba for the period from April 1992 to March 1993. New experimental investigations were made on (1) nuclear...

1993-01-01

375

Axisymmetric Tandem Mirror: A Magnetic Mirror Concept Game Changer Magnet Mirror Status Study Group.  

National Technical Information Service (NTIS)

Experimental results, theory and innovative ideas now point with increased confidence to the possibility of a Gas Dynamic Trap (GDT) neutron source which would be on the path to an attractively simple Axisymmetric Tandem Mirror (ATM) power plant. Although...

D. Correll D. Post H. Berk K. Fowler R. Cohen T. Simonen

2008-01-01

376

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

377

Tandem bis-aza-Michael addition reaction of amines in aqueous medium promoted by polystyrenesulfonic Acid  

EPA Science Inventory

An efficient and environmentally benign tandem bis-aza-Michael addition of amines catalyzed by polystyrene sulfonic acid (PSSA) is described. This operationally simple high yielding microwave assisted synthetic protocol proceeded in water in the absence of any organic solvent....

378

Tandem polymer solar cells featuring a spectrally matched low-bandgap polymer  

NASA Astrophysics Data System (ADS)

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, ~1.44 eV). A single-layer device based on the polymer provides a power conversion efficiency of ~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, Letian; You, Jingbi; Yang, Jun; Chen, Chun-Chao; He, Youjun; Murase, Seiichiro; Moriarty, Tom; Emery, Keith; Li, Gang; Yang, Yang

2012-03-01

379

Independently Regulated Neocentromere Activity of Two Classes of Tandem Repeat Arrays  

Microsoft Academic Search

Tandem repeat arrays often are found in interstitial (i.e., normally gene-rich) regions on chromosomes. In maize, genes on abnormal chromosome 10 induce the tandem repeats that make up knobs to move poleward on the meiotic spindle. This so-called neocentromere activity results in the preferential recovery, or meiotic drive, of the knobs in progeny. Here we show that two classes of

Evelyn N. Hiatt; Edward K. Kentner; R. Kelly Dawe

2002-01-01

380

Evaluation of automatically generated substructure identification rules from tandem mass spectra  

Microsoft Academic Search

Substructure identification rules for phenothiazine and barbiturate substructures were generated by using a new version of\\u000a the Method for Analyzing Patterns in Spectra (MAPS) software. This software uses tandem mass spectra and known substructure\\u000a content of reference compounds to provide “feature-combination“ rules. A feature-combination is a series of tandem mass spectral\\u000a features which are completely unique to compounds containing a

K. J. Hart; A. P. Wade; B. D. Nourse; C. G. Enke

1992-01-01

381

Algorithms for identifying protein cross-links via tandem mass spectrometry  

Microsoft Academic Search

Cross-linking technology combined with tandem mass spectrometry (MS-MS) is a powerful method that provides a rapid solution to the discovery of protein-protein interactions and protein structures. We studied the problem of detecting cross-linked peptides and cross-linked amino acids from tandem mass spectral data. Our method consists of two steps: the first step finds two protein subsequences whose mass sum equals

Ting Chen; Jacob D. Jaffe; George M. Church

2001-01-01

382

Analysis of amprolium by hydrophilic interaction liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

We present a fast liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) method for the analysis of the coccidiostat amprolium in food samples. Tandem mass spectrometry in a triple quadrupole was used for quantitative purposes, and the information from multiple-stage mass spectrometry in an ion-trap mass analyzer contributed to fragmentation studies. Hydrophilic interaction liquid chromatography (HILIC) in a Fused-Core™ column using isocratic elution

Anna Martínez-Villalba; Encarnación Moyano; M. Teresa Galceran

2010-01-01

383

Buildup studies of a tandem mirror reactor with inboard thermal barriers  

SciTech Connect

The build-up and quasi-steady state phases of the operation of the tandem mirror experiment, TMX, and of a tandem mirror machine with inboard thermal barriers, MFTF-B, have been simulated using a fluid model of the central cell and plug plasmas. The fluid model incorporates classical radial transport, three-dimensional cold gas transport in cylindrical geometry, and neutral beam transport corrected for finite-Larmor-orbit effects in both the central cell and yin yang end plugs.

Gryczkowski, G.E.; Gilmore, J.M.

1980-10-09

384

Realistic warhead and blast shield testing of chemical energy tandem warhead systems for advanced antitank missiles  

Microsoft Academic Search

The results of dynamic sled track performance testing of advanced tandem configuration shaped-charge warheads against multiple-reactive-element tank armors are presented. Tandem configurations utilizing both currently fielded and experimental shaped-charge warheads were tested. Sled velocities used were between 400 and 1100 ft\\/s (Mach number 0.35 to 0.95), typical of the terminal approach velocity of TOW-type antitank missiles. High-speed motion pictures (5000

D. B. Fradkin; L. M. Hull; G. W. Laabs

1990-01-01

385

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

386

Antiviral polypeptides comprising tandem repeats of APOE 141-149 and variants thereof  

US Patent & Trademark Office Database

The present invention concerns polypeptides derived from a tandem repeat of apoE.sub.141-149 and their uses as medicaments. The peptides may comprise the tandem repeat, and truncations thereof, for which at least one Leucine (L) is replaced by an amino acid with a side chain comprising at least 4 carbon atoms and at least one Nitrogen atom. Such peptides are useful for preventing or treating viral infections.

2010-04-06

387

Enhancement of photoinduced polarization rotation in azobenzene polymer films  

NASA Astrophysics Data System (ADS)

In this paper we demonstrated enhancement of photoinduced polarization rotation for improved transmission of laser light at low input intensities through a crossed polarized system. It is achieved by utilizing two azobenzene doped polymer thin films in tandem. As the input beam propagates through the films, its polarization rotation induced by each film is additive. We obtained polarization rotation of as much as 24° resulting in enhanced transmission compared to a single-film approach. In addition, this novel design is promising for use as a broadband nonlinear transmission system.

Yelleswarapu, Chandra S.; Chu, Yuanliang; Kimball, Brian R.; Rao, D. V. G. L. N.

2009-06-01

388

Planetary In Situ Sample Analysis with Tandem Two-Step Laser Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Future surface missions to comets and outer solar system satellites such as Europa, Enceladus, and Titan will benefit strongly from investigations that can detect a wide range of organics in complex sample mixtures and ices, as well as determine the structure of selected molecules, to provide insight into their origin and evolution. At the same time, such missions are likely to be among the most highly constrained in mass and power resources, particularly those flown within the tightly focused Discovery and New Frontiers programs. Techniques requiring minimal or no sample manipulation or preparation may be needed to reduce complexity. Pulsed laser-based mass spectrometry may satisfy such requirements, with total instrument masses potentially less than 5 kg, particularly where analysis of higher-molecular weight, nonvolatile species is a priority objective. Prototype flight-compatible mass spectrometers under active development in our lab are based on direct ultraviolet Nd:YAG laser desorption and ionization (LDI) of solid samples under high vacuum. Prompt ions from a single few ns-duration laser pulse are accelerated into a compact time-of-flight mass spectrometer (TOF-MS). Both inorganic species including elements and oxides such as M_xO_y (M = Mg, Al, Cl, Ca, Fe; x, y = 1-4) from the mineral matrix as well as organics with molecular weights up to several kDa are readily detected over a range of laser intensities. To improve our ability to distinguish among peaks and patterns in the often-complex LDI spectra obtained from natural samples, we have recently begun systematically testing several critical instrument enhancements. First, by moving the common voltage bias of the ion flight tube and detector to a common negative potential, we are able to switch between positive and negative ion detection modes with only electrostatic switching. Inter-comparison of cation and anion spectra can provide highly diagnostic information on both inorganic (e.g., Na+ and K+ vs. Cl-) and organic moieties. Second, by focusing a separate "post-ionization" laser pulse just above the sample surface, we can achieve two-step laser mass spectrometry, or L2MS, in the same highly-miniaturized TOF-MS. L2MS enables selective analysis of aromatic organics even in the presence of a complex mineral matrix. Finally, by introducing an ion optical gate in the flight path, we are able to take advantage of the broad focusing capabilities of the "curved field" reflectron at the core of the TOF-MS to achieve pseudo-tandem structural analysis of selected organics. The high-speed gate is used to admit only the molecular ion/s of interest into the reflectron. Diagnostic fragments of the ion/s obtained through metastable decay or active collision-induced dissociation (CID) remain in focus despite having widely variable velocities and masses. As such even molecular isomers with differing fragmentation pathways may be distinguished through a series of pseudo-tandem mass spectra that could be obtained in an automatic process during a mission. The "real-world" benefits of these enhancements are being fully characterized using a set of synthetic and natural standard samples as well as several planetary analogs and meteorites.

Brinckerhoff, W. B.; Getty, S. A.; Cornish, T. J.; Ecelberger, S. A.; Li, X.; Merrill Floyd, M. A.; Arevalo, R.; Elsila, J.; Callahan, M. P.

2012-12-01

389

Multipoint gap measurement by low coherence tandem interferometry  

NASA Astrophysics Data System (ADS)

Gap uniformity between two plates is an important parameter in many optical devices or instruments. The proposed method combines low coherence tandem interferometry and the concept of distributed fiber sensors for in-situ multipoint gap measurement. No gratins or special marks are required on the surfaces of the plates. A superluminescent diode (SLD) is used as the light source because of its low temporal coherence, high spatial coherence, and high optical power. Therefore, the proposed technique can also be easily implemented in free space. A collimated light beam from the SLD first passes through a scanning Michelson interferometer. The output of the interferometer is split into several separate beams, and then each beam is normally incident to the test sample at different positions. Gap distribution measurement is performed by sequentially opening the shutter behind each incident beam. A detector is employed to receive the reflected lights from the sample. The interferometric signal is recorded as a function of the arm-length difference of the scanning interferometer. The gap is eventually derived from the separation of the two side fringe packets, whose peak positions are determined by the centroid algorithm. Preliminary experimental results validate the feasibility of the presented method.

Lu, Sheng-Hua; Chang, Chi-Ying; Kao, Ching-Fen

2010-08-01

390

The Kinetic Stabilizer: A Route to Axisymmetric Tandem Mirror Systems  

NASA Astrophysics Data System (ADS)

Fusion research is presently dominated by the need to cope with the effects of plasma turbulence on confinement. If systems could be found in which turbulence levels are low the prospects for fusion could be drastically improved. The Kinetic Stabilizer [1] offers such an opportunity. It permits the design of MHD-stable tandem-mirror systems with axisymmetric fields. Cross-field transport in MHD-stable axisymmetric open-field systems can approach classical values [2], owing to the elimination of instability "drivers" endemic to closed systems. The K-S evolved from theory [3], confirmed experimentally, showing stabilization of MHD instability in axisymmetric mirror systems by plasma on the expanding field lines at the ends.. The K-S uses ion beams, compressed, stagnated, and reflected outside the mirrors to build plasma that stabilizes the T-M.. This paper will report on our theoretical and computational studies of the K.S. * Work performed under auspices of the US Department of Energy by the University of California Lawrence Livermore National Laboratory under contract W-7405-ENG-48 [1] R. F. Post, Trans. of Fusion Technology 39, 25 (2001) [2] P. A. Bagrynsky, et. al. Trans. of Fusion Technology 35, 79 (1999) [3] D. D. Ryutov, "Axisymmetric MHD-Stable Mirrors," Proc. of Course and Workshop, Varenna, Italy, Vol II, 791 (1987)

Post, R. F.; Bulmer, R. H.; Byers, J. A.; Fowler, T. K.; Ryutov, D. D.; Tung, L. S.

2003-10-01

391

Extraction of Builidng Shape from Tandem-X Data  

NASA Astrophysics Data System (ADS)

Large scale mapping and modeling of urban areas is requested in many fields, especially in planning of energy supply and for change detection. For this purpose, SAR systems are highly attractive due to their independency of daytime and weather. The new satellite configuration of TerraSAR-X and TanDEM-X provides single-pass 3D mapping of the earth with unprecedented geometric resolution, allowing for improved detection and extraction of building positions and shapes. In this paper, single-pass interferograms of the TanDEM-X mission are utilized to automatically reconstruct buildings. To this purpose, first an interferogram is calculated from a TanDEM pair. Then, a new detector is applied that analyses phase ramps in the interferogram. Phase ramps being a pattern typically observable in layover areas of buildings, the detector is able to indicate building locations. Afterwards, the detected building areas are analyzed in more detail to extract width, length, and height of the buildings. Last, an edge detector is applied to deduce the building shapes. The reconstruction results are compared with reference data.

Thiele, A.; Wurth, M. M.; Even, M.; Hinz, S.

2013-05-01

392

Reuse of denaturing polyacrylamide gels for short tandem repeat analysis.  

PubMed

Denaturing polyacrylamide gel electrophoretic analysis of amplified polymorphic short tandem repeat (STR) loci using fluorescent markers is a mainstay of forensic and paternity testing. To reduce the drawback of preparing gels or using expensive precast gels, we have developed a simple and rapid method to reuse gels between 2 and 8 times over a period of several days. Following the initial electrophoresis and scan, the original samples are removed from the gel by a 1-1.5-h reverse-electrophoresis step. This step heats the gel for the next set of samples and can be performed several days after the initial electrophoresis. Sample bands remain sharp on subsequent runs, but edge effects (frowning of the outside lanes) become progressively worse and ultimately limit gel reuse. Well distortions and separation of the gel from the plates become problems if the gel is used more than twice. However, degassing the gel solution and bonding the gel to both plates eliminate these problems. Precast gels also can be used multiple times. Using this technique, we have successfully analyzed samples amplified with a nine-locus multiplex system and characterized the separated products using a fluorescent scanner and software. PMID:9821592

Tereba, A; Micka, K A; Schumm, J W

1998-11-01

393

Tandem repeats in proteins: from sequence to structure.  

PubMed

The bioinformatics analysis of proteins containing tandem repeats requires special computer programs and databases, since the conventional approaches predominantly developed for globular domains have limited success. Here, I survey bioinformatics tools which have been developed recently for identification and proteome-wide analysis of protein repeats. The last few years have also been marked by an emergence of new 3D structures of these proteins. Appraisal of the known structures and their classification uncovers a straightforward relationship between their architecture and the length of the repetitive units. This relationship and the repetitive character of structural folds suggest rules for better prediction of the 3D structures of such proteins. Furthermore, bioinformatics approaches combined with low resolution structural data, from biophysical techniques, especially, the recently emerged cryo-electron microscopy, lead to reliable prediction of the protein repeat structures and their mode of binding with partners within molecular complexes. This hybrid approach can actively be used for structural and functional annotations of proteomes. PMID:21884799

Kajava, Andrey V

2012-09-01

394

Silicon wafer-based tandem cells: The ultimate photovoltaic solution?  

NASA Astrophysics Data System (ADS)

Recent large price reductions with wafer-based cells have increased the difficulty of dislodging silicon solar cell technology from its dominant market position. With market leaders expected to be manufacturing modules above 16% efficiency at 0.36/Watt by 2017, even the cost per unit area (60-70/m2) will be difficult for any thin-film photovoltaic technology to significantly undercut. This may make dislodgement likely only by appreciably higher energy conversion efficiency approaches. A silicon wafer-based cell able to capitalize on on-going cost reductions within the mainstream industry, but with an appreciably higher than present efficiency, might therefore provide the ultimate PV solution. With average selling prices of 156 mm quasi-square monocrystalline Si photovoltaic wafers recently approaching 1 (per wafer), wafers now provide clean, low cost templates for overgrowth of thin, wider bandgap high performance cells, nearly doubling silicon's ultimate efficiency potential. The range of possible Si-based tandem approaches is reviewed together with recent results and ultimate prospects.

Green, Martin A.

2014-03-01

395

Tandem mass spectrometric analysis of cyclophosphamide, ifosfamide and their metabolites.  

PubMed

A detailed multi-stage (MSn) fragmentation study of cyclophosphamide (CP), ifosfamide (IF) and their major metabolites, using an ion-trap mass spectrometer and a Q-TOF mass spectrometer, was performed with the aid of specifically deuterium-labeled analogs. The analytes showed good responses in positive-ion electrospray mass spectrometry as [MH]+ ions. Tandem mass spectra revealed a wealth of structurally specific ions, allowing characterization of the fragmentation pathways of these analytes. The major fragmentation pathways of the protonated CP and IF are elimination of ethylene from C5 and C6 of 1,3,2-oxazaphosphorine-2-oxide via a McLafferty rearrangement, and cleavage of the P-N bond. However, their activated 4-OOH and 4-OH metabolites primarily underwent hydrogen peroxide elimination and dehydration, respectively, followed by fragmentation pathways similar to those of CP and IF. These results should prove useful in structural elucidation of future analogs of CP and IF, and/or of their metabolites. PMID:16106352

Liu, Zhongfa; Chan, Kenneth K; Wang, Jeffrey J

2005-01-01

396

Biased cellular locations of tandem repeat antigens in African trypanosomes  

PubMed Central

Trypanosoma brucei subspecies cause African trypanosomiasis in humans and animals. These parasites possess genes encoding proteins with large tandem repeat (TR) domains as do the other trypanosomatid parasites. We have previously demonstrated that TR protein of Leishmania infantum and T. cruzi are often targets of B-cell responses. However, African trypanosomes are susceptible to antibody-mediated immunity, and it may be detrimental for the parasites to have such B-cell antigens on the cell surface. Here we show TR proteins of T. brucei subspecies are also antigenic: recombinant TR proteins of these parasites detect antibodies in sera from mice infected with the parasites by ELISA. Analysis of amino acid sequences revealed that, different from TR proteins of Leishmania species or T. cruzi, the presence of predicted signal peptides, trans-membrane domains and GPI anchor signals in T. brucei TR proteins are significantly lower than those of the whole proteome. Many of the T. brucei TR proteins are specific in the species or conserved only in the closely related species, as is the same case for L. major and T. cruzi. These results suggest that, despite their sharing some common characteristics, such abundance in large TR domains and immunological dominance, TR genes have evolved independently among the trypanosomatid parasites.

Goto, Yasuyuki; Duthie, Malcolm S.; Kawazu, Shin-Ichiro; Inoue, Noboru; Carter, Darrick

2011-01-01

397

Modeling tandem AAG8-MEK inhibition in melanoma cells  

PubMed Central

Drug resistance presents a challenge to the treatment of cancer patients, especially for melanomas, most of which are caused by the hyperactivation of MAPK signaling pathway. Innate or acquired drug-resistant relapse calls for the investigation of the resistant mechanisms and new anti-cancer drugs to provide implications for the ultimate goal of curative therapy. Aging-associated gene 8 (AAG8, encoded by the SIGMAR1 gene) is a chaperone protein profoundly elaborated in neurology. However, roles of AAG8 in carcinogenesis remain unclear. Herein, we discover AAG8 antagonists as new MEK inhibitors in melanoma cells and propose a novel drug combination strategy for melanoma therapy by presenting the experimental evidences. We report that specific antagonism of AAG8, efficiently suppresses melanoma cell growth and migration through, at least in part, the inactivation of the RAS-CRAF-MEK signaling pathway. We further demonstrate that melanoma cells that are resistant to AAG8 antagonist harbor refractory CRAF-MEK activity. MEK acts as a central mediator for anti-cancer effects and also for the resistance mechanism, leading to our proposal of tandem AAG8-MEK inhibition in melanoma cells. Combination of AAG8 antagonist and very low concentration of a MEK inhibitor synergistically restricts the growth of drug-resistant cells. These data collectively pinpoint AAG8 as a potential target and delineate a promising drug combination strategy for melanoma therapy.

Sun, Bing; Kawahara, Masahiro; Nagamune, Teruyuki

2014-01-01

398

A tandem mirror hybrid plume plasma propulsion facility  

SciTech Connect

A concept in electrodeless plasma propulsion, which is also capable of delivering a variable Isp, is presented. The concept involves a three-stage system of plasma injection, heating, and subsequent ejection through a magnetic nozzle. The nozzle produces the hybrid plume by the coaxial injection of hypersonic neutral gas. The gas layer, thus formed, protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The physics of this concept is evaluated numerically through full spatial and temporal simulations; these explore the operating characteristics of such a device over a wide region of parameter space. An experimental facility to study the plasma dynamics in the hybrid plume was built. The device consists of a tandem mirror operating in an asymmetric mode. A later upgrade of this system will incorporate a cold plasma injector at one end of the machine. Initial experiments involve the full characterization of the operating envelope, as well as extensive measurements of plasma properties at the exhaust. The results of the numerical simulations are described.

Chang-Diaz, F.R.; Yang, T.F.; Krueger, W.A.; Peng, S.; Urbahn, J.; Yao, X.; Griffin, D.

1988-01-01

399

Safety assessment of the MARS tandem mirror reactor  

SciTech Connect

The safety of the Mirror Advanced Reactor Study (MARS) tandem mirror reactor is assessed. Only prompt consequences to the public at the plant boundary, which is taken to be 1000m, are considered. The major radioactive inventories in MARS reside in the first-wall/blanket structure, coolant, and tritium. The greatest radioactivity resides in the HT-9 first-wall/ blanket structure. The only accident scenario identified that could lead to a first-wall meltdown was a loss-of-coolant accident (LOCA) accompanied by the inability to shut off the plasma. However, since only oxides of molybdenum are expected to be volatized from the hot HT-9 structure, the public consequences are found to be low. A LOCA can result in large doses if the activity in the activated corrosion products and LiPb coolant can be transported outside the reactor containment building. However, most of the LiPb would be expected to solidify, and any aerosols that are produced will likely plate out on surfaces or settle. Various tritium accident scenarios were considered. Release of all the tritium in the reactor building (51 g) leads to a dose of 21 rem. A much more likely accident involves partial leakage due to some reactor containment damage.

Guroi, H.; Dabiri, A.E.

1984-11-01

400

ECRH and ICRH in the TMX-U tandem mirror  

SciTech Connect

In the Tandem Mirror Experiment Upgrade (TMX-U), the formation of a thermal barrier and the potential plugging of ion end loss were achieved at central-cell densities up to 2 x 10/sup 12/ cm/sup -3/. The presence of a thermal barrier was confirmed by direct measurement, and ion axial-confinement times in the range 50 to 100 ms were measured. The ECRH in the end cells (a) initiates plasma startup, (b) generates hot, mirror-confined electrons to form thermal barriers, and (c) creates the plugging potential for central-cell ions. The ECRH system consists of four 200 kW, 28 GHz gyrotrons each feeding power to a separate heating location (two in each end plug). Fundamental heating is used at the potential plug, and second harmonic is used in the thermal barrier. Hot-electron plasmas are produced at total end-cell antenna power levels up to 300 kW. Strong single-pass absorption and net hot-electron heating efficiencies exceeding 40% are observed. Hot-electron parameters achieved are: n/sub eh//n/sub et/ up to 0.8, volume-average beta <..beta..> approx. = 0.15, and T/sub x/ (x-ray tail above 40 keV) in the range 75 to 200 keV.

Stallard, B.W.; Cummins, W.F.; Molvik, A.W.; Poulsen, P.; Simonen, T.C.; Falabella, S.; Barter, J.D.; Christensen, T.; Dimonte, G.; Romesser, T.E.

1984-03-15

401

Multilocus variable number tandem repeat analysis for Salmonella enterica subspecies.  

PubMed

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, and Newport). These allowed the selection of markers to develop the genotyping technique, multiple-locus VNTR analysis (MLVA). These markers were used to discriminate S. enterica isolated from humans, food, or the environment. In this report, the characteristics and specifications of 58 salmonella markers described from 2003 to 2009 are analyzed. Some VNTR loci were used as markers. The markers were used to discriminate S. enterica isolates from different sources and geographical localizations. Among the VNTR loci described in the published reports, eight presented with a high diversity index (DI) of polymorphism of more than 0.80. The selection of several markers within a single locus validated their polymorphism characteristic. Despite unequal DI values, the use of a panel of markers is a powerful discriminatory tool for the surveillance and identification of the source of salmonella outbreak. Depending on the markers selected, MLVA should be used either for macro- or microepidemiological purposes. The main challenge in the future for this technique is standardization. PMID:21153561

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

2011-04-01

402

Mutation rates of 15 X chromosomal short tandem repeat markers.  

PubMed

Though allele frequency data for a variety of X chromosomal short tandem repeat (STR) markers in a range of populations have been reported, fewer studies of mutation rates in these same markers or populations are available. In order to address possible mismatches during kinship analysis due to mutation, a robust estimate of the rate of mutation must be established. Here, mutation rates in three US populations have been determined for a total of 15 markers (DXS6789, DXS9902, DXS7132, DXS7130, DXS6795, DXS10147, DXS8378, DXS7423, HPRTB, DXS101, DXS7424, GATA31E08, GATA172D05, GATA165B12, and DXS6803). Eighteen mutations over 20,625 meioses were observed, and the overall X STR mutation rate in this study was found to be 8.73?×?10(-4) (95 % CI, 5.2-13.8?×?10(-4)). A review of published mutation rate studies revealed similar findings in other global populations, and allowed the compilation of a combined dataset of 81,310 meioses which can be employed by the forensic community. PMID:24811886

Diegoli, Toni M; Linacre, Adrian; Schanfield, Moses S; Coble, Michael D

2014-07-01

403

Measurements of the Flowfield Interaction Between Tandem Cylinders  

NASA Technical Reports Server (NTRS)

This paper presents the most recent measurements from an ongoing investigation of the unsteady wake interference between a pair of circular cylinders in tandem. The purpose of this investigation is to help build an in-depth experimental database for this canonical flow configuration that embodies the effects of component interaction in landing gear noise. This new set of measurements augments the previous database at the primary Reynolds number (based on tunnel speed and cylinder diameter) of 1.66 105 in four important respects. First, better circumferential resolution of surface pressure fluctuations is obtained via cylinder "clocking". Second, higher resolution particle image velocimetry measurements of the shear layer separating from the cylinders are achieved. Third, the effects of simultaneous boundary layer trips along both the front and rear cylinders, versus front cylinder alone in the previous measurements, are studied. Lastly, on-surface and off-surface characteristics of unsteady flow near the "critical" cylinder spacing, wherein the flow switches intermittently between two states that are characteristic of lower and higher spacings, are examined. This critical spacing occurs in the middle of a relatively sudden change in the drag of either cylinder and is characterized by a loud intermittent noise and a flow behavior that randomly transitions between shear layer attachment to the rear cylinder and constant shedding and rollup in front of it. Analysis of this bistable flow state reveals much larger spanwise correlation lengths of surface pressure fluctuations than those at larger and smaller values of the cylinder spacing.

Neuhart, Dan H.; Jenkins, Luther N.; Choudhari, Meelan M.; Khorrami, Mehdi R.

2009-01-01

404

Modeling tandem AAG8-MEK inhibition in melanoma cells.  

PubMed

Drug resistance presents a challenge to the treatment of cancer patients, especially for melanomas, most of which are caused by the hyperactivation of MAPK signaling pathway. Innate or acquired drug-resistant relapse calls for the investigation of the resistant mechanisms and new anti-cancer drugs to provide implications for the ultimate goal of curative therapy. Aging-associated gene 8 (AAG8, encoded by the SIGMAR1 gene) is a chaperone protein profoundly elaborated in neurology. However, roles of AAG8 in carcinogenesis remain unclear. Herein, we discover AAG8 antagonists as new MEK inhibitors in melanoma cells and propose a novel drug combination strategy for melanoma therapy by presenting the experimental evidences. We report that specific antagonism of AAG8, efficiently suppresses melanoma cell growth and migration through, at least in part, the inactivation of the RAS-CRAF-MEK signaling pathway. We further demonstrate that melanoma cells that are resistant to AAG8 antagonist harbor refractory CRAF-MEK activity. MEK acts as a central mediator for anti-cancer effects and also for the resistance mechanism, leading to our proposal of tandem AAG8-MEK inhibition in melanoma cells. Combination of AAG8 antagonist and very low concentration of a MEK inhibitor synergistically restricts the growth of drug-resistant cells. These data collectively pinpoint AAG8 as a potential target and delineate a promising drug combination strategy for melanoma therapy. PMID:24634165

Sun, Bing; Kawahara, Masahiro; Nagamune, Teruyuki

2014-06-01

405

The 2 MV tandem pelletron accelerator of the Louvre Museum  

NASA Astrophysics Data System (ADS)

The IBA facility of the Louvre Museum, code AGLAE, is based on the 6SDH-2 2 MV tandem Pelletron accelerator of NEC. A number of details of this machine have been specially designed with NEC to match the specific needs required for museum studies, i.e.: p, d, 3He, 4He, 15N beams from a single rf source, purely electrostatic focusing, halo-free submillimeter beam impacts, high-energy as well as low-energy operation at relatively high currents for resonance depth profiling of light nuclei including 1H, the possibility to automatize the machine operation as far as possible, development towards 14C AMS, and a microbeam extension. Special features of this machine include electrostatic steerers at the injection and electrostatic dog-leg steerers at the high-energy side, double slits at both sides of the accelerator, triplets instead of doublets for beam symmetry, turbomolecular recirculation of the stripper gas at the terminal, a new design of the stripper system itself, and a double feedback system with two capacitive pickoff plates for optimum energy spread and stability. The reasons of these special features will be explained and the characteristics of the machine as observed until now will be presented.

Amsel, G.; Menu, M.; Moulin, J.; Salomon, J.

1990-01-01

406

Peptide Identification by Tandem Mass Spectrometry with Alternate Fragmentation Modes*  

PubMed Central

The high-throughput nature of proteomics mass spectrometry is enabled by a productive combination of data acquisition protocols and the computational tools used to interpret the resulting spectra. One of the key components in mainstream protocols is the generation of tandem mass (MS/MS) spectra by peptide fragmentation using collision induced dissociation, the approach currently used in the large majority of proteomics experiments to routinely identify hundreds to thousands of proteins from single mass spectrometry runs. Complementary to these, alternative peptide fragmentation methods such as electron capture/transfer dissociation and higher-energy collision dissociation have consistently achieved significant improvements in the identification of certain classes of peptides, proteins, and post-translational modifications. Recognizing these advantages, mass spectrometry instruments now conveniently support fine-tuned methods that automatically alternate between peptide fragmentation modes for either different types of peptides or for acquisition of multiple MS/MS spectra from each peptide. But although these developments have the potential to substantially improve peptide identification, their routine application requires corresponding adjustments to the software tools and procedures used for automated downstream processing. This review discusses the computational implications of alternative and alternate modes of MS/MS peptide fragmentation and addresses some practical aspects of using such protocols for identification of peptides and post-translational modifications.

Guthals, Adrian; Bandeira, Nuno

2012-01-01

407

Measurements of Unsteady Wake Interference Between Tandem Cylinders  

NASA Technical Reports Server (NTRS)

A multi-phase, experimental study in the Basic Aerodynamics Research Tunnel at the NASA Langley Research Center has provided new insight into the unsteady flow interaction around cylinders in tandem arrangement. Phase 1 of the study characterized the mean and unsteady near-field flow around two cylinders of equal diameter using 2-D Particle Image Velocimetry (PIV) and hot-wire anemometry. These measurements were performed at a Reynolds number of 1.66 x 10(exp 5), based on cylinder diameter, and spacing-to-diameter ratios, L/D, of 1.435 and 3.7. The current phase, Phase 2, augments this dataset by characterizing the surface flow on the same configurations using steady and unsteady pressure measurements and surface flow visualization. Transition strips were applied to the front cylinder during both phases to produce a turbulent boundary layer upstream of the flow separation. For these flow conditions and L/D ratios, surface pressures on both the front and rear cylinders show the effects of L/D on flow symmetry, pressure recovery, and the location of flow separation and attachment. Mean streamlines and instantaneous vorticity obtained from the PIV data are used to explain the flow structure in the gap and near-wake regions and its relationship to the unsteady surface pressures. The combination of off-body and surface measurements provides a comprehensive dataset to develop and validate computational techniques for predicting the unsteady flow field at higher Reynolds numbers.

Jenkins, Luther N.; Neuhart, Dan H.; McGinley, Cahterine B.; Choudhari, Meelan M.; Khorrami, Mehdi R.

2006-01-01

408

Reduction of stutter ratios in short tandem repeat loci typing of low copy number DNA samples.  

PubMed

Increased height of stutter peaks is a phenomenon with low copy number (LCN) short tandem repeat (STR) typing that can impact interpretation. An alternative strategy of lowering the annealing/extension temperature (LT) at 56 °C was designed to attempt to decrease the heights of stutter peaks. STR typing results were generated in terms of stutter ratios using LT-PCR conditions and compared with data obtained using standard (STD) PCR conditions. DNA samples ranging from 100 to 25 pg were amplified using reagents contained in the AmpF?STR Identifiler PCR Amplification or AmpF?STR Identifiler Plus PCR Amplification kits with 32 or 34 PCR cycles. Stutter ratios decreased by an average of 14.7%, 14.9% and 18.1% at 100, 50 and 25 pg of template DNA under LT conditions compared with those of STD conditions in the Identifiler Kit amplified samples. The LT conditions also decreased average stutter ratios by 13.3% compared with those of STD conditions in the Identifiler Plus Kit amplified samples. The overall PCR efficiency obtained with STD and LT conditions with the two STR kits was comparable in terms of the number of detected alleles, peak heights and peak height ratios. These results support the hypothesis that a lower temperature annealing/extension step reduces the likelihood of slippage during PCR by enhancing the stability of the DNA polymerase/template DNA complex or the stability of the generated duplex than the conditions of the standard extension step. This stability in turn would result in lower stutter ratios. PMID:24315611

Seo, Seung Bum; Ge, Jianye; King, Jonathan L; Budowle, Bruce

2014-01-01

409

[Determination of aflatoxins in cashew by high performance liquid chromatography-tandem mass spectrometry].  

PubMed

A method for the determination of four aflatoxins in cashew using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The sample was extracted with methanol-water (8: 2, v/v) solution, followed by a cleanup procedure with Florisil column. The target compounds were eluted using 5 mL acetone-water-formic acid (96: 3.5:0.5, v/v/v) solution. The eluate was dried under N2, then dissolved in 1 mL methanol. Four aflatoxins were separated in MG C18 column (100 mm x 3.0 mm, 3 microm) adopting a gradient program within 15 min. A triple quadrupole mass spectrometry equipped with an electrospray ionization source operated in the positive ion mode was used to detect the aflatoxins. The good correlation coefficients (r2 > 0.997) of the four aflatoxins were obtained within their respective linear ranges. The limits of detection (S/N = 3) were between 0.009 microg/kg and 0.04 microg/kg, and the limits of quantification (S/N = 10) were between 0.03 microg/kg and 0.12 microg/kg. The recoveries were in a range of 63.0% -78.5% with the relative standard deviations (RSDs) varied from 2.8% to 9.1%. The validation results meet the requirements of trace assay. Matrix effects were estimated and the signal suppression/enhancement ranged from 88.8% to 99.4%. The results indicate that the developed method is simple, fast, accurate, and can be applied for the determination of fours aflatoxins in cashew. PMID:22500439

Bi, Ruifeng; Fan, Zhixian; Fu, Meng

2011-12-01

410

Performance-improved thin-film a-Si:H/?c-Si:H tandem solar cells by two-dimensionally nanopatterning photoactive layer.  

PubMed

Tandem solar cells consisting of amorphous and microcrystalline silicon junctions with the top junction nanopatterned as a two-dimensional photonic crystal are studied. Broadband light trapping, detailed electron/hole transport, and photocurrent matching modulation are considered. It is found that the absorptances of both junctions can be significantly increased by properly engineering the duty cycles and pitches of the photonic crystal; however, the photocurrent enhancement is always unevenly distributed in the junctions, leading to a relatively high photocurrent mismatch. Further considering an optimized intermediate layer and device resistances, the optimally matched photocurrent approximately 12.74 mA/cm2 is achieved with a light-conversion efficiency predicted to be 12.67%, exhibiting an enhancement of over 27.72% compared to conventional planar configuration. PMID:24521244

Zhang, Cheng; Li, Xiaofeng; Shang, Aixue; Zhan, Yaohui; Yang, Zhenhai; Wu, Shaolong

2014-01-01

411

Performance-improved thin-film a-Si:H/?c-Si:H tandem solar cells by two-dimensionally nanopatterning photoactive layer  

PubMed Central

Tandem solar cells consisting of amorphous and microcrystalline silicon junctions with the top junction nanopatterned as a two-dimensional photonic crystal are studied. Broadband light trapping, detailed electron/hole transport, and photocurrent matching modulation are considered. It is found that the absorptances of both junctions can be significantly increased by properly engineering the duty cycles and pitches of the photonic crystal; however, the photocurrent enhancement is always unevenly distributed in the junctions, leading to a relatively high photocurrent mismatch. Further considering an optimized intermediate layer and device resistances, the optimally matched photocurrent approximately 12.74 mA/cm2 is achieved with a light-conversion efficiency predicted to be 12.67%, exhibiting an enhancement of over 27.72% compared to conventional planar configuration.

2014-01-01

412

Comparative analysis of sequence features involved in the recognition of tandem splice sites  

PubMed Central

Background The splicing of pre-mRNAs is conspicuously often variable and produces multiple alternatively spliced (AS) isoforms that encode different messages from one gene locus. Computational studies uncovered a class of highly similar isoforms, which were related to tandem 5'-splice sites (5'ss) and 3'-splice sites (3'ss), yet with very sparse anecdotal evidence in experimental studies. To compare the types and levels of alternative tandem splice site exons occurring in different human organ systems and cell types, and to study known sequence features involved in the recognition and distinction of neighboring splice sites, we performed large-scale, stringent alignments of cDNA sequences and ESTs to the human and mouse genomes, followed by experimental validation. Results We analyzed alternative 5'ss exons (A5Es) and alternative 3'ss exons (A3Es), derived from transcript sequences that were aligned to assembled genome sequences to infer patterns of AS occurring in several thousands of genes. Comparing the levels of overlapping (tandem) and non-overlapping (competitive) A5Es and A3Es, a clear preference of isoforms was seen for tandem acceptors and donors, with four nucleotides and three to six nucleotides long exon extensions, respectively. A subset of inferred A5E tandem exons was selected and experimentally validated. With the focus on A5Es, we investigated their transcript coverage, sequence conservation and base-paring to U1 snRNA, proximal and distal splice site classification, candidate motifs for cis-regulatory activity, and compared A5Es with A3Es, constitutive and pseudo-exons, in H. sapiens and M. musculus. The results reveal a small but authentic enriched set of tandem splice site preference, with specific distances between proximal and distal 5'ss (3'ss), which showed a marked dichotomy between the levels of in- and out-of-frame splicing for A5Es and A3Es, respectively, identified a number of candidate NMD targets, and allowed a rough estimation of a number of undetected tandem donors based on splice site information. Conclusion This comparative study distinguishes tandem 5'ss and 3'ss, with three to six nucleotides long extensions, as having unusually high proportions of AS, experimentally validates tandem donors in a panel of different human tissues, highlights the dichotomy in the types of AS occurring at tandem splice sites, and elucidates that human alternative exons spliced at overlapping 5'ss posses features of typical splice variants that could well be beneficial for the cell.

Bortfeldt, Ralf; Schindler, Stefanie; Szafranski, Karol; Schuster, Stefan; Holste, Dirk

2008-01-01

413

Variation in Short Tandem Repeat sequences —a survey of twelve microsatellite loci for use as forensic identification markers  

Microsoft Academic Search

Alleles at 12 Short Tandem Repeat loci have been sequenced to investigate candidate loci for a multiplex Short Tandem Repeat system for forensic identification, and for single-locus amplification of Short Tandem Repeat loci. Variation from the consensus sequence was found at 6 loci, while one locus, D21S11, was found to be complex in sequence. The presence of non-consensus alleles does

A. Urquhart; C. P. Kimpton; T. J. Downes; P. Gill

1994-01-01

414

10.2% power conversion efficiency polymer tandem solar cells consisting of two identical sub-cells.  

PubMed

Polymer tandem solar cells with 10.2% power conversion efficiency are demonstrated via stacking two PDTP-DFBT:PC?? BM bulk heterojunctions, connected by MoO?/PEDOT:PSS/ZnO as an interconnecting layer. The tandem solar cells increase the power conversion efficiency of the PDTP-DFBT:PC?? BM system from 8.1% to 10.2%, successfully demonstrating polymer tandem solar cells with identical sub-cells of double-digit efficiency. PMID:23716123

You, Jingbi; Chen, Chun-Chao; Hong, Ziruo; Yoshimura, Ken; Ohya, Kenichiro; Xu, Run; Ye, Shenglin; Gao, Jing; Li, Gang; Yang, Yang

2013-08-01

415

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

416

Icariin enhances the healing of rapid palatal expansion induced root resorption in rats.  

PubMed

Icariin has been reported to enhance bone healing and treat osteoporosis. In this study, we examined the effect of Icariin on rapid palatal expansion induced root resorption in rats. Our hypothesis is that Icariin can enhance the healing of rapid palatal expansion induced root resorption. Forty-eight male Wistar rats were divided randomly and equally into three groups (n=16 rats each). The rats were untreated (negative control) or treated with rapid palatal expansion without (positive control) or with Icariin at 2.5 mg/kg day (Icariin-treated groups). An initial force of 50×g was applied to the areas between the right and left upper first molars of the rats for 21 days. Eight rats were randomly chosen from each group, and the root resorption index (RRI) was determined with scanning electron microscopy (SEM). Upper first molar-centered buccal- lingual tissue slices were generated from the upper first molars and peridentium of the remaining eight rats from each group. Specimen slices were analyzed with HE and tararate-resistant acid phosphatase staining, osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) immunohistochemistry, and optical microscopy. Analyses of cell number, densitometry, and one-way analysis of variance were performed. The Icariin-treated groups displayed decreased RRI values, decreased osteoclast numbers and activity levels, and increased OPG/RANKL expression ratios. High-power SEM revealed reparative cementum in the Icariin-treated samples. Icariin regulates osteoclast differentiation via the OPG/RANKL ratio, evoking a reparative effect on rapid palatal expansion induced root resorption in rats. PMID:22818561

Wang, Feng; Liu, Zhifeng; Lin, Songshan; Lu, Huaixiu; Xu, Juan

2012-08-15

417

Solution structure and tandem DNA recognition of the C-terminal effector domain of PmrA from Klebsiella pneumoniae  

PubMed Central

Klebsiella pneumoniae PmrA is a polymyxin-resistance-associated response regulator. The C-terminal effector/DNA-binding domain of PmrA (PmrAC) recognizes tandem imperfect repeat sequences on the promoters of genes to induce antimicrobial peptide resistance after phosphorylation and dimerization of its N-terminal receiver domain (PmrAN). However, structural information concerning how phosphorylation of the response regulator enhances DNA recognition remains elusive. To gain insights, we determined the nuclear magnetic resonance solution structure of PmrAC and characterized the interactions between PmrAC or BeF3?-activated full-length PmrA (PmrAF) and two DNA sequences from the pbgP promoter of K. pneumoniae. We showed that PmrAC binds to the PmrA box, which was verified to contain two half-sites, 5?-CTTAAT-3? and 5?-CCTAAG-3?, in a head-to-tail fashion with much stronger affinity to the first than the second site without cooperativity. The structural basis for the PmrAC–DNA complex was investigated using HADDOCK docking and confirmed by paramagnetic relaxation enhancement. Unlike PmrAC, PmrAF recognizes the two sites simultaneously and specifically. In the PmrAF–DNA complex, PmrAN may maintain an activated homodimeric conformation analogous to that in the free form and the interactions between two PmrAC molecules aid in bending and binding of the DNA duplex for transcription activation.

Lou, Yuan-Chao; Wang, Iren; Rajasekaran, M.; Kao, Yi-Fen; Ho, Meng-Ru; Hsu, Shang-Te Danny; Chou, Shan-Ho; Wu, Shih-Hsiung; Chen, Chinpan

2014-01-01

418

An Enhanced DNA Fingerprinting Service To Investigate Potential Clostridium difficile Infection Case Clusters Sharing the Same PCR Ribotype ?  

PubMed Central

Of 53 potential Clostridium difficile infection (CDI) case clusters/outbreaks, affecting 2 to 41 patients in 27 institutions, 19% comprised unrelated isolates and 34% had highly related and distinct isolates as shown by multilocus variable-number tandem-repeat analysis, despite sharing a common ribotype. These findings emphasize the value of enhanced fingerprinting to confirm or refute suspected CDI case clusters.

Fawley, Warren N.; Wilcox, Mark H.

2011-01-01

419

TiAlN/TiAlON/Si3N4 tandem absorber for high temperature solar selective applications  

NASA Astrophysics Data System (ADS)

A tandem absorber of TiAlN/TiAlON/Si3N4 is prepared using a magnetron sputtering process. The graded composition of the individual component layers of the tandem absorber produces a film with a refractive index increasing from the surface to the substrate, which exhibits a high absorptance (0.95) and a low emittance (0.07). The tandem absorber is stable in air up to 600 °C for 2 h, indicating its importance for high temperature solar selective applications. The thermal stability of the tandem absorber is attributed to high oxidation resistance and microstructural stability of the component materials at higher temperatures.

Barshilia, Harish C.; Selvakumar, N.; Rajam, K. S.; Sridhara Rao, D. V.; Muraleedharan, K.; Biswas, A.

2006-11-01

420

Profiling of Parkin-Binding Partners Using Tandem Affinity Purification  

PubMed Central

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting approximately 1–2% of the general population over age 60. It is characterized by a rather selective loss of dopaminergic neurons in the substantia nigra and the presence of ?-synuclein-enriched Lewy body inclusions. Mutations in the Parkin gene (PARK2) are the major cause of autosomal recessive early-onset parkinsonism. The Parkin protein is an E3 ubiquitin ligase with various cellular functions, including the induction of mitophagy upon mitochondrial depolarizaton, but the full repertoire of Parkin-binding proteins remains poorly defined. Here we employed tandem affinity purification interaction screens with subsequent mass spectrometry to profile binding partners of Parkin. Using this approach for two different cell types (HEK293T and SH-SY5Y neuronal cells), we identified a total of 203 candidate Parkin-binding proteins. For the candidate proteins and the proteins known to cause heritable forms of parkinsonism, protein-protein interaction data were derived from public databases, and the associated biological processes and pathways were analyzed and compared. Functional similarity between the candidates and the proteins involved in monogenic parkinsonism was investigated, and additional confirmatory evidence was obtained using published genetic interaction data from Drosophila melanogaster. Based on the results of the different analyses, a prioritization score was assigned to each candidate Parkin-binding protein. Two of the top ranking candidates were tested by co-immunoprecipitation, and interaction to Parkin was confirmed for one of them. New candidates for involvement in cell death processes, protein folding, the fission/fusion machinery, and the mitophagy pathway were identified, which provide a resource for further elucidating Parkin function.

Blankenburg, Hagen; Doncheva, Nadezhda T.; Schwienbacher, Christine; Serafin, Alice; Alexa, Adrian; Weichenberger, Christian X.; Albrecht, Mario; Klein, Christine; Hicks, Andrew A.; Pramstaller, Peter P.

2013-01-01

421

Deep conservation of human protein tandem repeats within the eukaryotes.  

PubMed

Tandem repeats (TRs) are a major element of protein sequences in all domains of life. They are particularly abundant in mammals, where by conservative estimates one in three proteins contain a TR. High generation-scale duplication and deletion rates were reported for nucleic TR units. However, it is not known whether protein TR units can also be frequently lost or gained providing a source of variation for rapid adaptation of protein function, or alternatively, tend to have conserved TR unit configurations over long evolutionary times. To obtain a systematic picture, we performed a proteome-wide analysis of the mode of evolution for human protein TRs. For this purpose, we propose a novel method for the detection of orthologous TRs based on circular profile hidden Markov models. For all detected TRs, we reconstructed bispecies TR unit phylogenies across 61 eukaryotes ranging from human to yeast. Moreover, we performed additional analyses to correlate functional and structural annotations of human TRs with their mode of evolution. Surprisingly, we find that the vast majority of human TRs are ancient, with TR unit number and order preserved intact since distant speciation events. For example, ? 61% of all human TRs have been strongly conserved at least since the root of all mammals, approximately 300 Ma. Further, we find no human protein TR that shows evidence for strong recent duplications and deletions. The results are in contrast to the high generation-scale mutability of nucleic TRs. Presumably, most protein TRs fold into stable and conserved structures that are indispensable for the function of the TR-containing protein. All of our data and results are available for download from http://www.atgc-montpellier.fr/TRE. PMID:24497029

Schaper, Elke; Gascuel, Olivier; Anisimova, Maria

2014-05-01

422

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

423

Deep Conservation of Human Protein Tandem Repeats within the Eukaryotes  

PubMed Central

Tandem repeats (TRs) are a major element of protein sequences in all domains of life. They are particularly abundant in mammals, where by conservative estimates one in three proteins contain a TR. High generation-scale duplication and deletion rates were reported for nucleic TR units. However, it is not known whether protein TR units can also be frequently lost or gained providing a source of variation for rapid adaptation of protein function, or alternatively, tend to have conserved TR unit configurations over long evolutionary times. To obtain a systematic picture, we performed a proteome-wide analysis of the mode of evolution for human protein TRs. For this purpose, we propose a novel method for the detection of orthologous TRs based on circular profile hidden Markov models. For all detected TRs, we reconstructed bispecies TR unit phylogenies across 61 eukaryotes ranging from human to yeast. Moreover, we performed additional analyses to correlate functional and structural annotations of human TRs with their mode of evolution. Surprisingly, we find that the vast majority of human TRs are ancient, with TR unit number and order preserved intact since distant speciation events. For example, ?61% of all human TRs have been strongly conserved at least since the root of all mammals, approximately 300 Ma. Further, we find no human protein TR that shows evidence for strong recent duplications and deletions. The results are in contrast to the high generation-scale mutability of nucleic TRs. Presumably, most protein TRs fold into stable and conserved structures that are indispensable for the function of the TR-containing protein. All of our data and results are available for download from http://www.atgc-montpellier.fr/TRE.

Schaper, Elke; Gascuel, Olivier; Anisimova, Maria

2014-01-01

424

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

425

Multivalent Binding of Formin-binding Protein 21 (FBP21)-Tandem-WW Domains Fosters Protein Recognition in the Pre-spliceosome*  

PubMed Central

The high abundance of repetitive but nonidentical proline-rich sequences in spliceosomal proteins raises the question of how these known interaction motifs recruit their interacting protein domains. Whereas complex formation of these adaptors with individual motifs has been studied in great detail, little is known about the binding mode of domains arranged in tandem repeats and long proline-rich sequences including multiple motifs. Here we studied the interaction of the two adjacent WW domains of spliceosomal protein FBP21 with several ligands of different lengths and composition to elucidate the hallmarks of multivalent binding for this class of recognition domains. First, we show that many of the proteins that define the cellular proteome interacting with FBP21-WW1-WW2 contain multiple proline-rich motifs. Among these is the newly identified binding partner SF3B4. Fluorescence resonance energy transfer (FRET) analysis reveals the tandem-WW domains of FBP21 to interact with splicing factor 3B4 (SF3B4) in nuclear speckles where splicing takes place. Isothermal titration calorimetry and NMR shows that the tandem arrangement of WW domains and the multivalency of the proline-rich ligands both contribute to affinity enhancement. However, ligand exchange remains fast compared with the NMR time scale. Surprisingly, a N-terminal spin label attached to a bivalent ligand induces NMR line broadening of signals corresponding to both WW domains of the FBP21-WW1-WW2 protein. This suggests that distinct orientations of the ligand contribute to a delocalized and semispecific binding mode that should facilitate search processes within the spliceosome.

Klippel, Stefan; Wieczorek, Marek; Schumann, Michael; Krause, Eberhard; Marg, Berenice; Seidel, Thorsten; Meyer, Tim; Knapp, Ernst-Walter; Freund, Christian

2011-01-01

426

Simulation of two dimensional electrophoresis and tandem mass spectrometry for teaching proteomics.  

PubMed

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. The two simulations are integrated together and are designed to teach the concept of proteome analysis of prokaryotic and eukaryotic organisms. 2DE-Tandem MS can be used as a freestanding simulation, or in conjunction with a wet lab, to introduce proteomics in the undergraduate classroom. 2DE Tandem MS is a free program available on Sourceforge at https://sourceforge.net/projects/jbf/. It was developed using Java Swing and functions in Mac OSX, Windows, and Linux, ensuring that every student sees a consistent and informative graphical user interface no matter the computer platform they choose. Java must be installed on the host computer to run 2DE Tandem MS. Example classroom exercises are provided in the Supporting Information. PMID:23166029

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

2012-01-01

427

3D numerical modeling of wave forces on tandem fixed cylinders using the BEM  

NASA Astrophysics Data System (ADS)

In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders. The fluid was considered to be inviscid and irrotational. Therefore, the Helmholtz equation was used as a governing equation. The boundary element method (BEM) was adopted to discretize the relevant equations. Open boundaries were used in far fields of the study domain. Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them. Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders, ka and kd on forces and trapped modes. The middle cylinder wave forces and trapped modes in a set of nine tandem cylinders were validated utilizing analytical data. The comparisons confirm the accuracy of the model. The results of the inline wave force estimation on n tandem cylinders show that the critical cylinder in the row is the middle one for odd numbers of cylinders. Furthermore the results show that the critical trapped mode effect occurs for normalized cylinder radiuses close to 0.5 and 1.0. Finally the force estimation for n tandem cylinders confirms that force amplitude of the middle cylinder versus normalized separation distance fluctuates about that of a single cylinder.

Ketabdari, Mohammad Javad; Abaiee, Mohammad Mahdi; Ahmadi, Ali

2013-09-01

428

Tandem organic light-emitting diode with a molybdenum tri-oxide thin film interconnector layer  

NASA Astrophysics Data System (ADS)

A 10-nm-thick molybdenum tri-oxide (MoO3) thin film was used as the interconnector layer in tandem organic light-emitting devices (OLEDs). The tandem OLEDs with two identical emissive units consisting of N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB)/tris(8-hydroxyquinoline) aluminum (Alq3) exhibited current efficiency-current density characteristics superior to the conventional single-unit devices. At 20 mA/cm2, the current efficiency of the tandem OLEDs using the interconnector layers of MoO3 thin film was about 4.0 cd/A, which is about twice that of the corresponding conventional single-unit device (1.8 cd/A). The tandem OLED showed a higher power efficiency than the conventional single-unit device for luminance over 1200 cd/m2. The experimental results demonstrated that a MoO3 thin film with a proper thickness can be used as an effective interconnector layer in tandem OLEDs. Such an interconnector layer can be easily fabricated by simple thermal evaporation, greatly simplifying the device processing and fabrication processes required by previously reported interconnector layers. A possible explanation was proposed for the carrier generation of the MoO3 interconnector layer.

Lu, Fei-Ping; Wang, Qian; Zhou, Xiang

2013-03-01

429

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

430

Generation of Tandem Direct Duplications by Reversed-Ends Transposition of Maize Ac Elements  

PubMed Central

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.

Peterson, Thomas

2013-01-01

431

Alkane metathesis by tandem alkane-dehydrogenation-olefin-metathesis catalysis and related chemistry.  

PubMed

Methods for the conversion of both renewable and non-petroleum fossil carbon sources to transportation fuels that are both efficient and economically viable could greatly enhance global security and prosperity. Currently, the major route to convert natural gas and coal to liquids is Fischer-Tropsch catalysis, which is potentially applicable to any source of synthesis gas including biomass and nonconventional fossil carbon sources. The major desired products of Fischer-Tropsch catalysis are n-alkanes that contain 9-19 carbons; they comprise a clean-burning and high combustion quality diesel, jet, and marine fuel. However, Fischer-Tropsch catalysis also results in significant yields of the much less valuable C(3) to C(8)n-alkanes; these are also present in large quantities in oil and gas reserves (natural gas liquids) and can be produced from the direct reduction of carbohydrates. Therefore, methods that could disproportionate medium-weight (C(3)-C(8)) n-alkanes into heavy and light n-alkanes offer great potential value as global demand for fuel increases and petroleum reserves decrease. This Account describes systems that we have developed for alkane metathesis based on the tandem operation of catalysts for alkane dehydrogenation and olefin metathesis. As dehydrogenation catalysts, we used pincer-ligated iridium complexes, and we initially investigated Schrock-type Mo or W alkylidene complexes as olefin metathesis catalysts. The interoperability of the catalysts typically represents a major challenge in tandem catalysis. In our systems, the rate of alkane dehydrogenation generally limits the overall reaction rate, whereas the lifetime of the alkylidene complexes at the relatively high temperatures required to obtain practical dehydrogenation rates (ca. 125 -200 °C) limits the total turnover numbers. Accordingly, we have focused on the development and use of more active dehydrogenation catalysts and more stable olefin-metathesis catalysts. We have used thermally stable solid metal oxides as the olefin-metathesis catalysts. Both the pincer complexes and the alkylidene complexes have been supported on alumina via adsorption through basic para-substituents. This process does not significantly affect catalyst activity, and in some cases it increases both the catalyst lifetime and the compatibility of the co-catalysts. These molecular catalysts are the first systems that effect alkane metathesis with molecular-weight selectivity, particularly for the conversion of C(n)n-alkanes to C(2n-2)n-alkanes plus ethane. This molecular-weight selectivity offers a critical advantage over the few previously reported alkane metathesis systems. We have studied the factors that determine molecular-weight selectivity in depth, including the isomerization of the olefinic intermediates and the regioselectivity of the pincer-iridium catalyst for dehydrogenation at the terminal position of the n-alkane. Our continuing work centers on the development of co-catalysts with improved interoperability, particularly olefin-metathesis catalysts that are more robust at high temperature and dehydrogenation catalysts that are more active at low temperature. We are also designing dehydrogenation catalysts based on metals other than iridium. Our ongoing mechanistic studies are focused on the apparently complex combination of factors that determine molecular-weight selectivity. PMID:22584036

Haibach, Michael C; Kundu, Sabuj; Brookhart, Maurice; Goldman, Alan S

2012-06-19