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

SciTech Connect

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

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



Synergistic induction of endothelin-1 by tumor necrosis factor alpha and interferon gamma is due to enhanced NF-kappaB binding and histone acetylation at specific kappaB sites.  


Endothelin-1 (ET-1) is a potent vasoconstrictor and co-mitogen for vascular smooth muscle and is implicated in pulmonary vascular remodeling and the development of pulmonary arterial hypertension. Vascular smooth muscle is an important source of ET-1. Here we demonstrate synergistic induction of preproET-1 message RNA and release of mature peptide by a combination of tumor necrosis factor alpha (TNFalpha) and interferon gamma (IFNgamma) in primary human pulmonary artery smooth muscle cells. This induction was prevented by pretreatment with the histone acetyltransferase inhibitor anacardic acid. TNFalpha induced a rapid and prolonged pattern of nuclear factor (NF)-kappaB p65 subunit activation and binding to the native preproET-1 promoter. In contrast, IFNgamma induced a delayed activation of interferon regulatory factor-1 without any effect on NF-kappaB p65 nuclear localization or consensus DNA binding. However, we found cooperative p65 binding and histone H4 acetylation at distinct kappaB sites in the preproET-1 promoter after stimulation with both TNFalpha and IFNgamma. This was associated with enhanced recruitment of RNA polymerase II to the ATG start site and read-through of the ET-1 coding region. Understanding such mechanisms is crucial in determining the key control points in ET-1 release. This has particular relevance to developing novel treatments targeted at the inflammatory component of pulmonary vascular remodeling. PMID:19592490

Wort, Stephen J; Ito, Misako; Chou, Pai-Chien; Mc Master, Shaun K; Badiger, Rekha; Jazrawi, Elen; de Souza, Patricia; Evans, Timothy W; Mitchell, Jane A; Pinhu, Liao; Ito, Kaz; Adcock, Ian M



A new member of the I kappaB protein family, I kappaB epsilon, inhibits RelA (p65)-mediated NF-kappaB transcription.  

PubMed Central

A novel member of the I kappaB family has been identified as a protein that associated with the p50 subunit of NF-kappaB in a yeast two-hybrid screen. Similar to previously known I kappaB proteins, this member, I kappaB epsilon, has six consecutive ankyrin repeats. I kappaB epsilon mRNA is widely expressed in different human tissues, with highest levels in spleen, testis, and lung. I kappaB epsilon interacts with different NF-kappaB proteins, including p65 (RelA), c-Rel, p50, and p52, in vitro and in vivo and inhibits the DNA-binding activity of both p50-p65 and p50-c-Rel complexes effectively. Endogenous and transfected NF-kappaB (RelA-dependent) transcriptional activation is inhibited by I kappaB epsilon. I kappaB epsilon mRNA is expressed at different levels in specific cell types and is synthesized constitutively in transformed B-cell lines. It also displays differential induction in response to tumor necrosis factor alpha, interleukin-1, or phorbol ester stimulation compared to I kappaB alpha in non-B-cell lines. Therefore, I kappaB epsilon represents a novel I kappaB family member which provides an alternative mechanism for regulation of NF-kappaB-dependent transcription. PMID:9315679

Li, Z; Nabel, G J



Intermediate reflectors for enhanced top cell performance in photovoltaic thin-film tandem cells.  


We have investigated the impact of three types of intermediate reflectors on the absorption enhancement in the top cell of micromorph tandem solar cells using rigorous diffraction theory. As intermediate reflectors we consider homogenous dielectric thin-films and 1D and 3D photonic crystals. Besides the expected absorption enhancements in cases where photonic band gaps are matched to the absorption edge of the semiconductor, our results distinguish between the impact of zero order Bragg-resonances and diffraction-based enhancement at larger lattice constants of the 3D photonic crystal. Our full-spectrum analysis permits for a quantitative prediction of the photovoltaic conversion efficiency increase of the a-Si:H top cell. PMID:19434178

Bielawny, Andreas; Rockstuhl, Carsten; Lederer, Falk; Wehrspohn, Ralf B



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


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



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

SciTech Connect

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

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



Curcumin promotes apoptosis, increases chemosensitivity, and inhibits nuclear factor kappaB in esophageal adenocarcinoma.  


The transcription factor, nuclear factor kappaB (NF-kappaB), plays a central role as a key mediator of cell survival and proliferation, and its activation may confer increased tumor chemoresistance. Curcumin, an orally available naturally occurring compound, has been shown to inhibit NF-kappaB and has a potential role in cancer chemoprevention. We investigated the effects of curcumin on NF-kappaB activity, on cell viability, and as a chemosensitizing agent with 5-fluorouracil (5-FU) or cisplatin (CDDP) in esophageal adenocarcinoma (EAC). Oligonucleotide microarray analysis of 46 cases, consisting of Barrett metaplasia, low-grade dysplasia, high-grade dysplasia and EAC, showed increased expression of NF-kappaB and IkappaB kinase subunits and decreased effector caspase expression in EAC compared with Barrett metaplasia. Stromal expression of both IkappaB and phospho-IkappaB was detected in several EAC samples by tissue microarray analysis. Curcumin alone inhibited NF-kappaB activity and induced apoptosis in both Flo-1 and OE33 EAC cell lines as determined by Western blot analysis, NF-kappaB reporter assays, and Caspase-Glo 3/7 assays. It also increased 5-FU- and CDDP-induced apoptosis in both cell lines. These data suggest that activation of NF-kappaB and inhibition of apoptosis may play a role in the progression from Barrett metaplasia to EAC. In addition, curcumin, a well-known inhibitor of NF-kappaB activity, was shown to increase apoptosis and enhance both 5-FU- and CDDP-mediated chemosensitivity, suggesting that it may have potential application in the therapy of patients with EAC. PMID:20360934

Hartojo, Wibisono; Silvers, Amy L; Thomas, Dafydd G; Seder, Christopher W; Lin, Lin; Rao, Hyma; Wang, Zhuwen; Greenson, Joel K; Giordano, Thomas J; Orringer, Mark B; Rehemtulla, Alnawaz; Bhojani, Mahaveer S; Beer, David G; Chang, Andrew C



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


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

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



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

PubMed Central

Sphingoid bases, such as unsaturated sphingosine (So) and its corresponding dihydro-saturated species sphinganine (Sa), are present in cell samples in low abundance. This fact combined with their low-to-moderate electrospray ionization (ESI) potential, compared to other sphingolipids such as sphingomyelins, limits their detection and quantitation by liquid chromatography tandem mass spectrometry (LC-MS2). To enhance the ESI efficiency of sphingoid bases, a novel procedure to generate stably derivatized analytes that enhance the LC-MS2 detection of sphingoid bases when analyzed using LC-MS2 was developed. In this method, a ruthenium complex, [4-(N-succimidyloxycarbonyl propyl)-4/-methy-2,2/-bipyridine] bis (2,2/-bipyridine) Ru(11) dihexafluorophosphate, is added directly to a cell extract. This complex reacts with and covalently binds to an amino group within the sphingoid bases. The dicationic nature of the ruthenium ion, enhances the compound’s ionization efficiency resulting in increased LC-MS2 signals for the derivatized sphingoid bases. Consequently, the detection and quantitation of sphingoid bases is greatly improved. PMID:19055420

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



Modulation of SCF beta-TrCP-dependent I kappaB alpha ubiquitination by hydrogen peroxide.  


Reactive oxygen species are known to participate in the regulation of intracellular signaling pathways, including activation of NF-kappaB. Recent studies have indicated that increases in intracellular concentrations of hydrogen peroxide (H(2)O(2)) have anti-inflammatory effects in neutrophils, including inhibition of the degradation of I kappaB alpha after TLR4 engagement. In the present experiments, we found that culture of lipopolysaccharide-stimulated neutrophils and HEK 293 cells with H(2)O(2) resulted in diminished ubiquitination of I kappaB alpha and decreased SCF(beta-TrCP) ubiquitin ligase activity. Exposure of neutrophils or HEK 293 cells to H(2)O(2) was associated with reduced binding between phosphorylated I kappaB alpha and SCF(beta-TrCP) but no change in the composition of the SCF(beta-TrCP) complex. Lipopolysaccharide-induced SCF(beta-TrCP) ubiquitin ligase activity as well as binding of beta-TrCP to phosphorylated I kappaB alpha was decreased in the lungs of acatalasemic mice and mice treated with the catalase inhibitor aminotriazole, situations in which intracellular concentrations of H(2)O(2) are increased. Exposure to H(2)O(2) resulted in oxidative modification of cysteine residues in beta-TrCP. Cysteine 308 in Blade 1 of the beta-TrCP beta-propeller region was found to be required for maximal binding between beta-TrCP and phosphorylated I kappaB alpha. These findings suggest that the anti-inflammatory effects of H(2)O(2) may result from its ability to decrease ubiquitination as well as subsequent degradation of I kappaB alpha through inhibiting the association between I kappaB alpha and SCF(beta-TrCP). PMID:19933270

Banerjee, Sami; Zmijewski, Jaroslaw W; Lorne, Emmanuel; Liu, Gang; Sha, Yonggang; Abraham, Edward



"New turns from old STaRs": Enhancing the capabilities of forensic short tandem repeat analysis.  


The field of research and development of forensic STR genotyping remains active, innovative, and focused on continuous improvements. A series of recent developments including the introduction of a sixth dye have brought expanded STR multiplex sizes while maintaining sensitivity to typical forensic DNA. New supplementary kits complimenting the core STRs have also helped improve analysis of challenging identification cases such as distant pairwise relationships in deficient pedigrees. This article gives an overview of several recent key developments in forensic STR analysis: availability of expanded core STR kits and supplementary STRs, short-amplicon mini-STRs offering practical options for highly degraded DNA, Y-STR enhancements made from the identification of rapidly mutating loci, and enhanced analysis of genetic ancestry by analyzing 32-STR profiles with a Bayesian forensic classifier originally developed for SNP population data. As well as providing scope for genotyping larger numbers of STRs optimized for forensic applications, the launch of compact next-generation sequencing systems provides considerable potential for genotyping the sizeable proportion of nucleotide variation existing in forensic STRs, which currently escapes detection with CE. PMID:24888494

Phillips, Christopher; Gelabert-Besada, Miguel; Fernandez-Formoso, Luis; García-Magariños, Manuel; Santos, Carla; Fondevila, Manuel; Ballard, David; Syndercombe Court, Denise; Carracedo, Angel; Victoria Lareu, Maria



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. PMID:21492457



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


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

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



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


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



A Y-short tandem repeat specific DNA enhancement strategy to aid the analysis of late reported (?6 days) sexual assault cases.  


The ability to obtain an autosomal short tandem repeat (STR) profile of the semen donor from the reproductive tract of a living victim rapidly diminishes as the post-coital interval increases. This is of concern where victims of sexual assault provide vaginal samples several days after the incident. In order to overcome the technological impediments inherent in autosomal DNA typing with extended interval samples, we previously employed the use of Y chromosome STR profiling which, by targeting only male DNA, can eliminate masking of the male profile (by the victim's alleles) or critical polymerase chain reaction reagent titration (due to excessive female DNA). Thus employing Y-STR profiling and additional enhancement strategies, we reported the ability to recover Y-STR profiles from samples collected 5 to 6 days after intercourse. However, the reproductive biology literature indicates that spermatozoa are found in the human cervix up to 7 to 10 days post coitus. Thus, even with improved extraction and profiling techniques, we failed to routinely recover profiles from samples collected ?6 days after intercourse. The aim of the present work was to develop additional strategies to permit the recovery of male donor DNA profiles from ?6 post-coital samples. Using nested polymerase chain reaction and DNA concentration procedures that together maximize the recovery and targeting of male DNA, we demonstrate the ability to obtain semen donor Y-STR profiles in extended interval post-coital samples collected 6 to 9 days after intercourse. This approaches the recognized time limits of sperm residence in the cervico-vaginal canal as described in the clinical literature. PMID:24526669

Hanson, Ek; Ballantyne, J



Enhanced methamphetamine metabolism in rhesus macaque as compared with human: an analysis using a novel method of liquid chromatography with tandem mass spectrometry, kinetic study, and substrate docking.  


Methamphetamine (MA), which remains one of the widely used drugs of abuse, is metabolized by the cytochrome P450 (P450) family of enzymes in humans. However, metabolism of methamphetamine in macaques is poorly understood. Therefore, we first developed and validated a very sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) method using solid phase extraction of rhesus plasma with a lower limit of quantitation at 1.09 ng/ml for MA and its metabolites, 4-hydroxy methamphetamine (4-OH MA), amphetamine (AM), 4-OH amphetamine (4-OH AM), and norephedrine. We then analyzed plasma samples of MA-treated rhesus, which showed >10-fold higher concentrations of AM (?29 ng/ml) and 4-OH AM (?28 ng/ml) than MA (?2 ng/ml). Because the plasma levels of MA metabolites in rhesus were much higher than in human samples, we examined MA metabolism in human and rhesus microsomes. Interestingly, the results showed that AM and 4-OH AM were formed more rapidly and that the catalytic efficiency (Vmax/Km) for the formation of AM was ?8-fold higher in rhesus than in human microsomes. We further examined the differences in these kinetic characteristics using three selective inhibitors of each human CYP2D6 and CYP3A4 enzymes. The results showed that each of these inhibitors inhibited both d- and l-MA metabolism by 20%-60% in human microsomes but not in rhesus microsomes. The differences between human and rhesus CYP2D6 and CYP3A4 enzymes were further assessed by docking studies for both d and l-MA. In conclusion, our results demonstrated an enhanced MA metabolism in rhesus compared with humans, which is likely to be caused by differences in MA-metabolizing P450 enzymes between these species. PMID:25301936

Earla, Ravinder; Kumar, Santosh; Wang, Lei; Bosinger, Steven; Li, Junhao; Shah, Ankit; Gangwani, Mohitkumar; Nookala, Anantha; Liu, Xun; Cao, Lu; Jackson, Austin; Silverstein, Peter S; Fox, Howard S; Li, Weihua; Kumar, Anil



Targeting receptor-activator of nuclear kappaB ligand in aneurysmal bone cysts: verification of target and therapeutic response.  


Aneurysmal bone cyst (ABC) is a benign tumor of bone presenting as a cystic, expansile lesion in both the axial and appendicular skeleton. Axial lesions demand special consideration, because treatment-related morbidity can be devastating. In similar lesions, such as giant cell tumor of bone (GCTB), the receptor-activator of nuclear kappaB ligand (RANKL)-receptor-activator of nuclear kappaB (RANK) signaling axis is essential to tumor progression. Although ABC and GCTB are distinct entities, they both contain abundant multinucleated giant cells and are osteolytic characteristically. We hypothesize that ABCs express both RANKL and RANK similarly in a cell-type specific manner, and that targeted RANKL therapy will mitigate ABC tumor progression. Cellular expression of RANKL and RANK was determined in freshly harvested ABC samples using laser confocal microscopy. A consistent cell-type-specific pattern was observed: fibroblastlike stromal cells expressed RANKL strongly whereas monocyte/macrophage precursor and multinucleated giant cells expressed RANK. Relative RANKL expression was determined by quantitative real-time polymerase chain reaction in ABC and GCTB tissue samples; no difference in relative expression was observed (P > 0.05). In addition, we review the case of a 5-year-old boy with a large, aggressive sacral ABC. After 3 months of targeted RANKL inhibition with denosumab, magnetic resonance imaging demonstrated tumor shrinkage, bone reconstitution, and healing of a pathologic fracture. Ambulation, and bowel and bladder function were restored at 6 months. Denosumab treatment was well tolerated. Post hoc analysis demonstrated strong RANKL expression in the pretreatment tumor sample. These findings demonstrate that RANKL-RANK signal activation is essential to ABC tumor progression. RANKL-targeted therapy may be an effective alternative to surgery in select ABC presentations. PMID:24726460

Pelle, Dominic W; Ringler, Jonathan W; Peacock, Jacqueline D; Kampfschulte, Kevin; Scholten, Donald J; Davis, Mary M; Mitchell, Deanna S; Steensma, Matthew R



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.



Tandem mobile robot system  


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)



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.



Monolithic tandem solar cell  


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

Wanlass, Mark W. (Golden, CO)



Monolithic tandem solar cell  


A single-crystal, monolithic, tandem, photovoltaic solar cell is described which includes (a) an InP substrate having upper and lower surfaces, (b) a first photoactive subcell on the upper surface of the InP substrate, (c) a second photoactive subcell on the first subcell; and (d) an optically transparent prismatic cover layer over the second subcell. The first photoactive subcell is GaInAsP of defined composition. The second subcell is InP. The two subcells are lattice matched. 9 figs.

Wanlass, M.W.



Negative tandem mirror  

SciTech Connect

A tandem mirror configuration can be created by combining hot electron end cell plasmas with neutral beam pumping. A region of large negative potential formed in each end cell confines electrons in the central cell. The requirement of charge neutrality causes the central cell potential to become negative with respect to ground in order to confine ions as well as electrons. We discuss the method of producing and calculating the desired axial potential profile, and show the calculated axial potential profile and plasma parameters for a negative configuration of TMX-Upgrade.

Poulsen, P.; Allen, S.L.; Casper, T.A.; Grubb, D.P.; Jong, R.A.; Nexsen, W.E.; Porter, G.D.; Simonen, T.C.



MASPIC: Intensity-Based Tandem Mass Spectrometry Scoring Scheme That Improves Peptide Identification at High Confidence  

Microsoft Academic Search

Algorithmic search engines bridge the gap between large tandem mass spectrometry data sets and the identification of proteins associated with biological samples. Improvements in these tools can greatly enhance biological discovery. We present a new scoring scheme for comparing tandem mass spectra with a protein sequence database. The MASPIC (Multinomial Algorithm for Spectral Profile-based Intensity Comparison) scorer converts an experimental

Chandrasegaran NMN Narasimhan; David L. Tabb; Nathan C. VerBerkmoes; Melissa R. Thompson; Robert L. Hettich; Edward C. Uberbacher



Influence of hormone replacement therapy on osteoprotegerin and receptor activator of nuclear factor kappa-B ligand concentrations in menopausal women.  


The study was designed to compare the levels of the receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the serum and saliva of menopausal women and verify whether there is a correlation between concentrations of these cytokines and bone mineral density (BMD) of the femur and mandible. Blood and saliva samples were collected from a group of 60 women during menopause--30 untreated (control group) and 30 treated with hormone replacement therapy (HRT) (research group). Densitometry was conducted on the femoral bone and mandible. BMD in the research group was significantly higher than in the control group. The OPG concentration was slightly higher in the research group. The concentration of RANKL was slightly higher in the control group. Differences in RANKL/OPG between groups were not high enough to be statistically significant. Analysis of the RANKL in saliva revealed a significantly higher concentration of this factor in the control group. Observed beneficial effects of HRT on bone tissue may be exerted through the RANKL/OPG ratio, but further research is required to clearly confirm this thesis. PMID:23745763

Rahnama, Mansur; Jastrz?bska-Jamrogiewicz, Izabela; Jamrogiewicz, Rafa?; Nogalski, Adam; Jagielak, Maciej



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

SciTech Connect

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

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



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:



Monolithic Tandem Organic Photovoltaic Cell Utilizing Transparent Carbon Nanotube Interlayer  

NASA Astrophysics Data System (ADS)

We demonstrate an organic photovoltaic multijunction cell in a monolithic parallel tandem structure in which transparent multi and single-walled nanotube sheets are used as an interlayer electrode connecting two cells; polymeric photovoltaic (PPV) cell or organic low molecular PV (OPV). Each cell is characterized independently and the short circuit current density of the tandem is shown to be larger than individual cells for the PPV-MWCNT-OPC tandem*. Overall efficiency is increased attributed to effective use of transparent CNTs and enhanced spectral sensitivity due to differing active layer materials.Computer model circuit simulation is used to analyze the parameters of cells in parallel and series configurations. Advantages of a parallel connection is shown for PV cells with differing photocurrents. The PPV-CNT-PPV and OPV-CNT-OPV cells are also created and described. *S.Tanaka, K Mielczarek,, APL. (submitted 2008, October).

Mielczarek, Kamil; Tanaka, Senku; Ovalle Robles, Raquel; Kuznetsov, Alexander; Wang, Brian; Hsu, Dean; Baughman, Ray; Zakhidov, Anvar



Tandem Cylinder Noise Predictions  

NASA Technical Reports Server (NTRS)

In an effort to better understand landing-gear noise sources, we have been examining a simplified configuration that still maintains some of the salient features of landing-gear flow fields. In particular, tandem cylinders have been studied because they model a variety of component level interactions. The present effort is directed at the case of two identical cylinders spatially separated in the streamwise direction by 3.7 diameters. Experimental measurements from the Basic Aerodynamic Research Tunnel (BART) and Quiet Flow Facility (QFF) at NASA Langley Research Center (LaRC) have provided steady surface pressures, detailed off-surface measurements of the flow field using Particle Image Velocimetry (PIV), hot-wire measurements in the wake of the rear cylinder, unsteady surface pressure data, and the radiated noise. The experiments were conducted at a Reynolds number of 166 105 based on the cylinder diameter. A trip was used on the upstream cylinder to insure a fully turbulent shedding process and simulate the effects of a high Reynolds number flow. The parallel computational effort uses the three-dimensional Navier-Stokes solver CFL3D with a hybrid, zonal turbulence model that turns off the turbulence production term everywhere except in a narrow ring surrounding solid surfaces. The current calculations further explore the influence of the grid resolution and spanwise extent on the flow and associated radiated noise. Extensive comparisons with the experimental data are used to assess the ability of the computations to simulate the details of the flow. The results show that the pressure fluctuations on the upstream cylinder, caused by vortex shedding, are smaller than those generated on the downstream cylinder by wake interaction. Consequently, the downstream cylinder dominates the noise radiation, producing an overall directivity pattern that is similar to that of an isolated cylinder. Only calculations based on the full length of the model span were able to capture the complete decay in the spanwise correlation, thereby producing reasonable noise radiation levels.

Lockhard, David P.; Khorrami, Mehdi R.; CHoudhari, Meelan M.; Hutcheson, Florence V.; Brooks, Thomas F.; Stead, Daniel J.



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




NSDL National Science Digital Library

It doesn't take a Photoshop expert to create attractive graphics for the Web. To prove this, the folks at MicroFrontier have released three graphic creation/editing packages for the Macintosh, each aimed at a different user level. All three applications support Photoshop 3.0 compatible plug-ins and basic features such as scanner support, image and resolution scaling, and basic image enhancement. Enhance, aimed at the graphics professionals, adds even more features, including multiple layers, opacity control, sixteen levels of undo, convolution filter effects, and CYMK support. A save-disabled demo version of each application is available at the MicroFrontier Website. The price for Enhance is $100 .



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.



Improved tandem mirror fusion reactor  

Microsoft Academic Search

It is shown that the introduction of barrier potentials between the plugs and solenoid of a tandem mirror substantially reduce ion energy and density required in end plugs. Several means for creating barriers and some of the important physics issues are discussed.

D. E. Baldwin; B. G. Logan



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



Tandem hemodialysis and plasma exchange.  


The combination of hemodialysis and plasma exchange as one tandem procedure was first described in 1999 by Siami et al. (ASAIO J 45:229-233), but larger pediatric case series were not described until 2012. Even in adults, there are only limited case series. If performed in sequence, up to 8 h of treatment time may be required. With the use of the tandem procedure in stable patients, the same procedures can be completed during the same time as a routine hemodialysis, which is more convenient for patients and may reduce healthcare costs. Little is known about the utilization of the combination of hemodialysis and plasma exchange in children. The purpose of this review is to summarize the adult and scarce pediatric experience. The results of a survey carried out by the authors using the Internet listserver "PedNeph" to obtain an overview of the current practice patterns of pediatric nephrologists are also presented. PMID:24022368

Filler, Guido; Clark, William F; Huang, Shih-Han S



"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



The characterization of tandem and corrugated wings  

NASA Astrophysics Data System (ADS)

Dragonfly wings have two distinct features: a tandem configuration and wing corrugation. Both features have been extensively studied with the aim to understand the superior flight performance of dragonflies. In this paper we review recent development of tandem and corrugated wing aerodynamics. With regards to the tandem configuration, this review will focus on wing/wing and wing/vortex interactions at different flapping modes and wing spacing. In addition, the aerodynamics of tandem wings under gusty conditions will be reviewed and compared with isolated wings to demonstrate the gust resistance characteristics of flapping wings. Regarding corrugated wings, we review their structural and aerodynamic characteristics.

Lian, Yongsheng; Broering, Timothy; Hord, Kyle; Prater, Russell



The IAE Peking HI-13 tandem accelerator  

NASA Astrophysics Data System (ADS)

A new tandem accelerator laboratory is under construction at the Institute of Atomic Energy in Peking. This institute was built in 1958 and equipped with a reactor, cyclotron, electrostatic accelerator and some other facilities to meet the increasing interest in nuclear study and its application in China. The project of this tandem laboratory was approved in 1978. A 13 MV tandem accelerator will be provided by the High Voltage Engineering Corporation of Burlington, Massachusetts, USA, and a Q3D magnetic spectrometer by AB Scanditronix, Sweden. Some auxiliary systems, experimental equipment and the tank of the tandem are being designed and manufactured in China.

Ju-xian, Yu



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




Microsoft Academic Search

The Bucharest FN Tandem Accelerator was put in operation in 1973 and upgraded a first time in 1983 to 9 MV. In the period 2006-2009 a second program of the tandem upgrade was performed aiming to transform this accelerator in a modern and versatile facility for atomic and nuclear physics studies as well as for different applications using accelerated ion

S. Dobrescu; I. Branzan; C. V. Craciun; G. Dumitru; C. Florea; D. Ghita; G. Ion; G. Mihon; D. Moisa; D. V. Mosu; G. Naghel; C. Paun; S. Papureanu; T. Sava


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



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

Microsoft Academic Search

Neuronal injury in manganese neurotoxicity (manganism) is thought to involve activation of astroglial cells and subsequent overproduction of nitric oxide (NO) by inducible nitric oxide synthase (NOS2). Manganese (Mn) enhances the effects of proinflammatory cytokines on expression of NOS2 but the molecular basis for this effect has not been established. It was postulated in the present studies that Mn enhances

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



Radiometric cross-calibration of the Landsat7 ETM+ and Landsat5 TM sensors based on tandem data sets  

Microsoft Academic Search

Early in its mission, the Landsat-7 spacecraft was temporarily placed in a “tandem” orbit very close to that of the Landsat-5 spacecraft in order to facilitate the establishment of sensor calibration continuity between the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-5 Thematic Mapper (TM) sensors. The key period for the tandem configuration was June 1–4, 1999, during which hundreds

P. m. Teillet; J. l. Barker; B. l. Markham; R. R Irish; G. Fedosejevs; J. c. Storey



The thermodynamic limits of tandem photovoltaic devices with intermediate band  

NASA Astrophysics Data System (ADS)

We present a hybrid thermodynamic model for multijunction solar cells with intermediate bands that demonstrates possible improvements to conventional multijunction photovoltaic systems. Applying this model to selected tandem cell structures shows that the performance of such hybrid solar cells is enhanced and that multiple transitions from intermediate bands can reduce the number of material stacks and boost overall efficiency. We demonstrate the results of detailed simulations for multiple numbers of stacks of hybrid multijunction solar cells. And, we can choose proper materials to compose intermediate band for each junction. Furthermore, we suggest other alternative hybrid solar cell systems to absorb moderate photon energy range and find appropriate materials for hybrid solar cells.

Lee, Jongwon; Honsberg, Christiana B.



Computer Aided Design on the Tandem Mirror Experiment Upgrade (TMX-U).  

National Technical Information Service (NTIS)

The Tandem Mirror Experiment-Upgrade (TMX-U) at Lawrence Livermore National Laboratory (LLNL) has been using a Computer Aided Design (CAD) graphics system to enhance its design capabilities since November of 1984. Three-dimensional models of the TMX-U mag...

G. L. Brandt, M. O. Calderon, V. L. Williamson



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


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

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



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.



Oak Ridge 25-MV tandem accelerator  

SciTech Connect

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

Jones, C.M.



On decision making in tandem networks  

E-print Network

We study the convergence of Bayesian learning in a tandem social network. Each agent receives a noisy signal about the underlying state of the world, and observes her predecessor's action before choosing her own. We ...

Dia, Manal



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

SciTech Connect

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

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



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. PMID:23452340



Phosphatidylcholine-specific phospholipase C and phospholipase D are respectively implicated in mitogen-activated protein kinase and nuclear factor kappaB activation in tumour-necrosis-factor-alpha-treated immature acute-myeloid-leukaemia cells.  


Tumour necrosis factor-alpha (TNFalpha) has been reported to induce potent growth inhibition of committed myeloid progenitor cells, whereas it is a potential growth stimulator of human CD34(+)CD38(-) multipotent haematopoietic cells. The present study was aimed at evaluating the respective role of two phospholipases, phosphatidylcholine-specific phospholipase C (PC-PLC) and phospholipase D (PLD) in the response of the CD34(+) CD38(-) KG1a cells to TNFalpha. In these cells TNFalpha triggered phosphoinositide 3-kinase (PI3K)-dependent PC hydrolysis within 4-8 min with concomitant production of both diacylglycerol (DAG) and phosphocholine (P-chol). DAG and P-chol production was accompanied by extracellular-signal-related protein kinase-1 ('ERK-1') activation and DNA-synthesis stimulation. PC-PLC stimulation was followed by PI3K-independent PLD activation with concomitant phosphatidic acid (PA) production followed by PA-derived DAG accumulation and sustained nuclear factor kappaB (NF-kappaB) activation. PLD/NF-kappaB signalling activation played no role in the TNFalpha proliferative effect and conferred no consistent protection of KG1a cells towards antileukaemic agents. Altogether these results suggest that, in KG1a cells, TNFalpha can stimulate in parallel PC-PLC and PLD, whose lipid products activate in turn mitogen-activated protein kinase (MAP kinase) and NF-kappaB signalling respectively. Finally, our study suggests that PC-PLC, but not PLD, plays a role in the TNFalpha proliferative effect in immature myeloid cells. PMID:11023832

Plo, I; Lautier, D; Levade, T; Sekouri, H; Jaffrézou, J P; Laurent, G; Bettaïeb, A



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.)



Tandem transformation of glycerol to esters.  


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

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



Alpha particle confinement in tandem mirrors  

SciTech Connect

Mechanisms leading to loss of alpha particles from non-axisymmetric tandem mirrors are considered. Stochastic diffusion due to bounce-drift resonances, which can cause rapid radial losses of high-energy alpha particles, can be suppressed by imposing a 20% rise in axisymmetric fields before the quadrupole transition sections. Alpha particles should then be well-confined until thermal energies when they enter the resonant plateau require. A fast code for computation of drift behavior in reactors is described. Sample calculations are presented for resonant particles in a proposed coil set for the Tandem Mirror Next Step.

Devoto, R.S.; Ohnishi, M.; Kerns, J.; Woo, J.T.



Tandem mirror thermal barrier experimental program plan  

SciTech Connect

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

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



[Screening of newborns for inborn errors of metabolism by tandem mass spectrometry].  


Tandem mass spectrometry is an analytical method which is being implemented for neonatal screening. The method can determine the content of amino acids and acylcarnitines in neonatal screening samples in one integrated analysis. This allows detection of more than 20 inherited disorders of amino acid, fatty acid and organic acid metabolism. The aggregate incidence of these disorders is in the order of 1:4000. The principal disease which is detectable is medium-chain acyl-CoA dehydrogenase deficiency, which has an incidence of 1:10,000-1:20,000 in Northern Europe. Medium-chain acyl-CoA dehydrogenase deficiency puts the affected at risk of life-threatening metabolic crises, which are preventable if the condition has been diagnosed. Hence, the prognosis is excellent. The central theme for therapeutic management of medium-chain acyl-CoA dehydrogenase deficiency is carbohydrate supplementation, especially in situations of intercurrent illness. Tandem mass spectrometry screening will also enhance the present screening for phenylketonuria which employs a bacterial assay: the screening sample can be obtained 48-72 hours post partum, the false-positive rate will be reduced, and there will be no interference with antibiotics. Tandem mass spectrometry is being used in state-mandated screening panels in a few places and is being tested in pilot studies in many other places. A national prospective pilot project was launched on February 1, 2002 in Denmark. The project includes tandem mass spectrometry screening for galactosemia. In addition to neonatal screening, tandem mass spectrometry can be used for investigation of metabolic diseases, sudden unexpected death of infancy and shaken baby syndrome. Critical appraisal of tandem mass spectrometry will lead to improved health for infants affected by rare inherited disorders of metabolism. PMID:12523003

Simonsen, Henrik



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


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



Tandem mass spectrometry in the clinical chemistry laboratory  

Microsoft Academic Search

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

Kent C. Dooley



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



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.



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.



Tandem oligonucleotide synthesis using linker phosphoramidites  

PubMed Central

Multiple oligonucleotides of the same or different sequence, linked end-to-end in tandem can be synthesized in a single automated synthesis. A linker phosphoramidite [R. T. Pon and S. Yu (2004) Nucleic Acids Res., 32, 623–631] is added to the 5?-terminal OH end of a support-bound oligonucleotide to introduce a cleavable linkage (succinic acid plus sulfonyldiethanol) and the 3?-terminal base of the new sequence. Conventional phosphoramidites are then used for the rest of the sequence. After synthesis, treatment with ammonium hydroxide releases the oligonucleotides from the support and cleaves the linkages between each sequence. Mixtures of one oligonucleotide with both 5?- and 3?-terminal OH ends and other oligonucleotides with 5?-phosphorylated and 3?-OH ends are produced, which are deprotected and worked up as a single product. Tandem synthesis can be used to make pairs of PCR primers, sets of cooperative oligonucleotides or multiple copies of the same sequence. When tandem synthesis is used to make two self-complementary sequences, double-stranded structures spontaneously form after deprotection. Tandem synthesis of oligonucleotide chains containing up to six consecutive 20mer (120 bases total), various trinucleotide codons and primer pairs for PCR, or self-complementary strands for in situ formation of double-stranded DNA fragments has been demonstrated. PMID:15814811

Pon, Richard T.; Yu, Shuyuan



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



MASPIC: Intensity-Based Tandem Mass Spectrometry Scoring Scheme That Improves Peptide Identification at High Confidence  

SciTech Connect

Algorithmic search engines bridge the gap between large tandem mass spectrometry data sets and the identification of proteins associated with biological samples. Improvements in these tools can greatly enhance biological discovery. We present a new scoring scheme for comparing tandem mass spectra with a protein sequence database. The MASPIC (Multinomial Algorithm for Spectral Profile-based Intensity Comparison) scorer converts an experimental tandem mass spectrum into a m/z profile of probability and then scores peak lists from potential candidate peptides using a multinomial distribution model. The MASPIC scoring scheme incorporates intensity, spectral peak density variations, and m/z error distribution associated with peak matches into a multinomial distribution. The scoring scheme was validated on two standard protein mixtures and an additional set of spectra collected on a complex ribosomal protein mixture from Rhodopseudomonas palustris. The results indicate a 5-15% improvement over Sequest for high-confidence identifications. The performance gap grows as sequence database size increases. Additional tests on spectra from proteinase-K digest data showed similar performance improvements demonstrating the advantages in using MASPIC for studying proteins digested with less specific proteases. All these investigations show MASPIC to be a versatile and reliable system for peptide tandem mass spectral identification.

Narasimhan, Chandrasegaran NMN [ORNL; Tabb, Dave L [ORNL; Verberkmoes, Nathan C [ORNL; Thompson, Melissa R [ORNL; Hettich, Robert {Bob} L [ORNL; Uberbacher, Edward C [ORNL



Measurements of the hot-electron density during thermal-barrier operation in a tandem mirror experiment  

SciTech Connect

Thermal-barrier operation of a tandem mirror requires the generation of a dense population of energetic, mirror-trapped electrons. This has been confirmed by experimental results from the initial thermal-barrier experiments in the Tandem Mirror Experiment-Upgrade (Phys. Rev. Lett. 53, 783 (1984)). For discharges with similar operating conditions, a dramatic enhancement of the axial confinement time was observed only when the mirror-confined hot-electron density was a large fraction of the total electron density at the position of the thermal barrier. These results are in excellent agreement with theoretical predictions.

James, R.A.; Ellis, R.F.; Lasnier, C.J.; Grubb, D.P.; Casper, T.A.



Tandem microwave waste remediation and decontamination system  


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)



LLNL multi-user tandem laboratory  

NASA Astrophysics Data System (ADS)

The Physics Department at Lawrence Livermore National Laboratory (LLNL) is building a new tandem Van de Graaff laboratory for nuclear physics and applied physics and technology programs. The laboratory has been funded by a coalition of users including several LLNL divisions, Sandia National Laboratories Livermore, and the University of California. The tandem is the former University of Washington injector FN. The accelerator is upgraded with a Pelletron charging system, Dowlish spiral inclined field beam tubes and SF 6 insulation. The laboratory incorporates several novel design concepts. Initial operation will be in June, 1987 with full operation in October, 1987. Design features, radiological controls, computer assisted operation, and experimental facilities of the laboratory are discussed.

Proctor, I. D.; Davis, J. C.; Eaton, M. R.; Garibaldi, J. L.; Moore, T. L.; Schumacher, B. J.; Southon, J. R.; Zimmerman, T. A.



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.



Development of 1 MV tandem proton accelerator  

Microsoft Academic Search

A 1MV Tandem Proton Accelerator is being developed for the industrial applications such as high-energy implantation and explosive detection. The proton accelerator consists of a 10 mA negative hydrogen ion source, two Einzel lenses, accelerating tubes, a gas stripper, a 1MV 30 mA Cockroft-Walton high voltage power supply, vacuum pumping system, and a high pressure insulating gas system. The large

Y. S. Cho; W. S. Song; B. H. Choi



Current and lattice matched tandem solar cell  


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)



DDES and IDDES of tandem cylinders.  

SciTech Connect

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

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



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.



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


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)



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)



Ion activation methods for tandem mass spectrometry.  


This tutorial presents the most common ion activation techniques employed in tandem mass spectrometry. In-source fragmentation and metastable ion decompositions, as well as the general theory of unimolecular dissociations of ions, are initially discussed. This is followed by tandem mass spectrometry, which implies that the activation of ions is distinct from the ionization step, and that the precursor and product ions are both characterized independently by their mass/charge ratios. In collision-induced dissociation (CID), activation of the selected ions occurs by collision(s) with neutral gas molecules in a collision cell. This experiment can be done at high (keV) collision energies, using tandem sector and time-of-flight instruments, or at low (eV range) energies, in tandem quadrupole and ion trapping instruments. It can be performed using either single or multiple collisions with a selected gas and each of these factors influences the distribution of internal energy that the activated ion will possess. While CID remains the most common ion activation technique employed in analytical laboratories today, several new methods have become increasingly useful for specific applications. More recent techniques are examined and their differences, advantages and disadvantages are described in comparison with CID. Collisional activation upon impact of precursor ions on solid surfaces, surface-induced dissociation (SID), is gaining importance as an alternative to gas targets and has been implemented in several different types of mass spectrometers. Furthermore, unique fragmentation mechanisms of multiply-charged species can be studied by electron-capture dissociation (ECD). The ECD technique has been recognized as an efficient means to study non-covalent interactions and to gain sequence information in proteomics applications. Trapping instruments, such as quadrupole ion traps and Fourier transform ion cyclotron resonance instruments, are particularly useful for the photoactivation of ions, specifically for fragmentation of precursor ions by infrared multiphoton dissociation (IRMPD). IRMPD is a non-selective activation method and usually yields rich fragmentation spectra. Lastly, blackbody infrared radiative dissociation is presented with a focus on determining activation energies and other important parameters for the characterization of fragmentation pathways. The individual methods are presented so as to facilitate the understanding of each mechanism of activation and their particular advantages and representative applications. PMID:15481084

Sleno, Lekha; Volmer, Dietrich A




E-print Network

ERROR VISUALIZATION FOR TANDEM ACOUSTIC MODELING ON THE AURORA TASK Manuel J. Reyes. This structure reduces the error rate on the Aurora 2 noisy English digits task by more than 50% compared development of tandem systems showed an improvement in the performance on the Aurora task [2] of these systems

Ellis, Dan


Vacuum insulation tandem accelerator for B. Bayanov1  

E-print Network

273 Vacuum insulation tandem accelerator for NCT B. Bayanov1 , Yu. Belchenko1 , V. Belov1 , G of high current hydrogen negative ions by special geometry of potential electrodes with vacuum insulation. Fig. 1 shows the construction of vacuum insulation tandem accelerator developed at BINP, as a base

Taskaev, Sergey Yur'evich


Speckle-phase measurement in a tandem-vortex coronagraph.  


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



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



Tandem-Free Operation for VoIP Conference Bridges  

E-print Network

Tandem-Free Operation for VoIP Conference Bridges Paxton J. Smith, Peter Kabal, Maier Blostein-- Traditional telephone conferencing has been accom- plished by way of a centralized conference bridge. The tandem arrangement of high compression speech codecs in conventional VoIP conference bridges lead

Kabal, Peter


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.



Theoretical studies in tandem mirror physics  

SciTech Connect

Recent developments in six areas of tandem-mirror theory are explored. Specifically, FLR terms (including electric-field drift) have been added to our 3-D paraxial MHD equilibrium code. Our low-frequency MHD stability analysis with FLR, which previously included only m/sub theta/ = 1 rigid perturbations, has been extended to incorporate moderate m/sub theta/, rotational drive, finite-beta effects on wall stabilization, and the well-digging effect of energetic electrons by using three computational techniques. In addition, we have examined the microstability of relativistic electrons with a loss-cone distribution, emphasizing the whistler and cyclotron-maser instabilities. We have also studied techniques for controlling radial transport, including the floating of segmented end plates and the tuning of transition-region coils, and have quantified the residual transport in a tandem mirror with axisymmetric throttle coils. Earlier work on the effect of ECRH on potentials in thermal-barrier cells has been extended. The transition between the weak- and strong-heating regimes has been examined using Fokker-Planck and Monte Carlo codes; an analytic model for the potentials relative to the end wall has been developed. Finally, our investigation of drift-frequency pumping of thermal-barrier ions has demonstrated that pumping is optimized when the magnetic fluctuation is perpendicular to both the unperturbed field and the thin fan, and that an adequate pumping rate is obtainable in future machines.

Cohen, R.H.; Auerbach, S.P.; Baldwin, D.E.; Byers, J.A.; Chen, Y.J.; Cohen, B.I.; Freis, R.P.; Gilmore, J.M.; Hammer, J.H.; Kaiser, T.B.



Efficient tandem synthesis of methyl esters and imines by using versatile hydrotalcite-supported gold nanoparticles.  


Efficient basic hydrotalcite (HT)-supported gold nanoparticle (AuNP) catalysts have been developed for the aerobic oxidative tandem synthesis of methyl esters and imines from primary alcohols catalyzed under mild and soluble-base-free conditions. The catalytic performance can be fine-tuned for these cascade reactions by simple adjustment of the Mg/Al atomic ratio of the HT support. The one-pot synthesis of methyl esters benefits from high basicity (Mg/Al = 5), whereas moderate basicity greatly improves imine selectivity (Mg/Al = 2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies show a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidation of the starting alcohol but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the composition of the support has been shown to yield optimum AuNP catalysts for different tandem reactions. PMID:22893610

Liu, Peng; Li, Can; Hensen, Emiel J M



Family of short, interspersed repeats is associated with tandemly repetitive DNA in the human genome  

SciTech Connect

A family of short, interspersed repeats in the human genome, designated the Mst II family, is described. The canonical structure of the repeat consists of a 220-base-pair (bp) left arm joined to a 160-bp right arm by a 39-bp junction sequence. The right arm is absent in some isolates. Some homology with the O and THE (transposon-like element) families of repeats was observed, suggesting that the Mst II elements could be a subgroup of a SINE superfamily. The 39-bp junction sequence is tandemly repeated in one of our clones. The association of tandemly repetitive sequences with Mst II elements or the putative superfamily is probably nonrandom; a search of DNA sequences data bases revealed that approximately 80 bp of the Mst II left arm occurs immediately adjacent to the tandem repeat that comprises the human homologue to the BK virus enhancer. The fortuitous occurrence of a gene duplication event involving an Mst II repeat has allowed us to estimate a mutation rate of human DNA.

Mermer, B.; Colb, M.; Krontiris, T.G.



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

ERIC Educational Resources Information Center

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

Cziko, Gary A.



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.



Dual analyte detection using tandem flash luminescence.  


A heterogeneous, dual analyte-binding assay which makes use of the flash luminescence from both aequorin and an acridinium-9-carboxamide label is presented. The signal generating species were triggered both differentially and sequentially using Ca(2+) followed by basic peroxide. Both signals were resolved readily using a single photomultiplier tube without the need for multiwavelength detection. To demonstrate the tandem luminescence concept in a model assay system, dose-response curves for two analytes, biotinylated BSA and myoglobin, were generated using a competitive binding format. Because of the relatively short assay time and the well-resolved signals, this format will be useful in the development of dual analyte high-throughput assays. PMID:11814805

Adamczyk, Maciej; Moore, Jeffrey A; Shreder, Kevin



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


Intragenic tandem repeats generate functional variability  

PubMed Central

Tandemly repeated DNA sequences are highly dynamic components of genomes1. Most repeats are in intergenic regions, but some are found within coding sequences or pseudogenes2. In humans, expansion of intragenic triplet repeats is associated with various diseases, including Huntington’s chorea and fragile X syndrome3,4. The persistence of intragenic repeats in genomes argues in favor of a compensating benefit. Here we show that in the Saccharomyces genome, the majority of the genes containing intragenic repeats encode cell wall proteins. The repeats trigger frequent recombination events within the gene or between the gene and a pseudogene, causing expansion and contraction in the gene size. This size variation creates quantitative alterations in phenotypes (e.g. adhesion, flocculation, biofilm formation). We propose that variation in intragenic repeat number provides the functional diversity of cell surface antigens that, in fungi and other pathogens, allows rapid adaptation to the environment and/or elusion of the host immune system. PMID:16086015

Verstrepen, Kevin J.; Jansen, An; Lewitter, Fran; Fink, Gerald R.



Status of tandem-mirror confinement  

NASA Astrophysics Data System (ADS)

Recent end-stopping experiments in TMX-Upgrade show strong plugging of the central cell by lower-density plugs, requiring both electron-cyclotron heating (ECRH) and 470 neutral-beam injection, consistent with the thermal-barrier concept. These experiments have low density (n 10 to the 12th power/cu cm) due to inefficient ECRH power coupling. Hot-ion and hot-electron buildup are consistent with Fokker-Planck calculations. No ion-cyclotron activity is observed in the plugs; occasional electron-cyclotron activity is observed. With plugging, axial lifetimes (tau/sub parallel/ 40 ms) are larger than radial (tau/sub perpendicular/ = 5 to 10 ms) due to observed non-ambipolar ion transport. Recent tandem-mirror theoretical activities are also surveyed.

Baldwin, D. E.



Recent Activities in Tandem, Booster and TRIAC at Tokai  

NASA Astrophysics Data System (ADS)

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

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



A tandem-based compact dual-energy gamma generator  

SciTech Connect

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. [E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Antolak, A. J.; Morse, D. H.; Raber, T. [Sandia National Laboratories, Livermore, California 94550 (United States)



Short tandem repeat (STR) profile authentication via machine learning techniques  

E-print Network

Short tandem repeat (STR) DNA profiles have multiple uses in forensic analysis, kinship identification, and human biometrics. However, as biotechnology progresses, there is a growing concern that STR profiles can be created ...

Shcherbina, Anna



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


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

Sivula, Kevin



The Bucharest Tandem Accelerator — part of the European Infrastructure  

Microsoft Academic Search

The Bucharest Tandem van de Graaff accelerator in Bucharest is described. The scientific program in both applied and basic research is outlined. Through many international collaborations, the accelerator is, indeed, part of the European Nuclear Physics Research infrastructure.

Nicolae Victor Zamfir



The Bucharest Tandem Accelerator - part of the European Infrastructure  

Microsoft Academic Search

The Bucharest Tandem van de Graaff accelerator in Bucharest is described. The scientific program in both applied and basic research is outlined. Through many international collaborations, the accelerator is, indeed, part of the European Nuclear Physics Research infrastructure.

Nicolae Victor Zamfir; Nicolae Victor



Argonne tandem as injector to a superconducting linac  

SciTech Connect

The Argonne Tandem uses Pelletron chains, NEC accelerator tubes, and a dual closed-corona system. Its main function is to be an injector for a superconducting linear accelerator. As long as the transverse and longitudinal emittances are within the acceptance of the linac, the output beam quality of the tandem-linac system is essentially determined by the tandem. The sensitivity of the linac to the longitudinal emittance of the incident beam makes the output beam quality dependent on the negative-ion velocity distribution in the source, transit-time effects in the tandem, molecular-beam dissociation, and stripper-foil uniformity. This paper discusses these beam-degrading effects.

Yntema, J.L.; Den Hartog, P.K.; Henning, W.; Kutschera, W.



Protein Identification from Tandem Mass Spectra with Probabilistic Language Modeling  

Microsoft Academic Search

This paper presents an interdisciplinary investigation of statistical information retrieval (IR) techniques for protein identification from tandem mass spectra, a challenging problem in proteomic data analysis. We formulate the task as an IR problem, by constructing a \\

Yiming Yang; Abhay Harpale; Subramaniam Ganapathy



Patterns of tandem repetition in plant whole genome assemblies  

Microsoft Academic Search

Tandem repeats often confound large genome assemblies. A survey of tandemly arrayed repetitive sequences was carried out in\\u000a whole genome sequences of the green alga Chlamydomonas\\u000a reinhardtii, the moss Physcomitrella patens, the monocots rice and sorghum, and the dicots Arabidopsis thaliana, poplar, grapevine, and papaya, in order to test how these assemblies deal with this fraction of DNA. Our results

Rafael Navajas-Pérez; Andrew H. Paterson



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 PMID:22121222

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



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



Sequence Database Compression for Peptide Identification from Tandem Mass Spectra  

Microsoft Academic Search

The identification of peptides from tandem mass spectra is an important part of many high-throughput proteomics pipelines. In the high-throughput setting, the spectra are typically identified using software that matches tandem mass spectra with putative peptides from amino-acid sequence databases. The effectiveness of these search engines depends heavily on the completeness of the amino-acid sequence database used, but suitably complete

Nathan Edwardsand; Ross Lippert



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.



Transcriptome annotation using tandem SAGE tags  

PubMed Central

Analysis of several million expressed gene signatures (tags) revealed an increasing number of different sequences, largely exceeding that of annotated genes in mammalian genomes. Serial analysis of gene expression (SAGE) can reveal new Poly(A) RNAs transcribed from previously unrecognized chromosomal regions. However, conventional SAGE tags are too short to identify unambiguously unique sites in large genomes. Here, we design a novel strategy with tags anchored on two different restrictions sites of cDNAs. New transcripts are then tentatively defined by the two SAGE tags in tandem and by the spanning sequence read on the genome between these tagged sites. Having developed a new algorithm to locate these tag-delimited genomic sequences (TDGS), we first validated its capacity to recognize known genes and its ability to reveal new transcripts with two SAGE libraries built in parallel from a single RNA sample. Our algorithm proves fast enough to experiment this strategy at a large scale. We then collected and processed the complete sets of human SAGE tags to predict yet unknown transcripts. A cross-validation with tiling arrays data shows that 47% of these TDGS overlap transcriptional active regions. Our method provides a new and complementary approach for complex transcriptome annotation. PMID:17709346

Rivals, Eric; Boureux, Anthony; Lejeune, Mireille; Ottones, Florence; Pecharroman Perez, Oscar; Tarhio, Jorma; Pierrat, Fabien; Ruffle, Florence; Commes, Therese; Marti, Jacques



Tandem-mirror technology demonstration facility  

SciTech Connect

Preliminary calculations at LLNL indicate that a Technology Demonstration Facility (TDF) consisting of a tandem mirror machine about the size of TMX could begin providing fusion nuclear engineering data as early as 1988. With high density operation based on physics already demonstrated in TMX, this machine would produce 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 would permit testing of blanket modules and components at 1 MW/m/sup 2/ neutron wall load over a cylindrical surface 8 m/sup 2/ in area at a radius of 0.25 m; or one could irradiate thousands of small samples at 2 MW/m/sup 2/ at r = 0.125 m (4 m/sup 2/ area). With improved end-plug physics to be tested in TMX-Upgrade in 1982-83, the wall load at 0.25 m could be increased to 2 MW/m/sup 2/ (4 MW/m/sup 2/ at r = 0.125 m). Construction of the TDF could begin in FY84 and be completed in 4 to 5 years, at a cost roughly estimated as $700M in '81 dollars including engineering and 30% contingency.

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



Traditional and modern medicine working in tandem.  


Because of the many problems relating to health care delivery in Africa, it is becoming apparent that neither the exclusive/monopolistic nor the tolerant legislative systems should be tolerated any longer. Especially since the Alma Ata Conference held by the WHO/UNICEF there has been growing impetus towards either inclusive/parallel (the beneficial co-existence of traditional and modern medical systems), or integrated systems. Although the idea of making traditional and modern medicine work in tandem in a united treatment context has its merits, it is also plagued by issues such as the nature of the products of an integrated training, resistance by stubborn protagonists of either of the two systems, or that only lip-service is paid to the idea of co-operation. Nevertheless, it is believed that all interest groups--the authorities responsible for health care delivery, the Western-trained health care workers, the traditional healers and the users of these services--stand to gain from such liaison. PMID:1845633

Pretorius, E



Landmarks and ant search strategies after interrupted tandem runs.  


During a tandem run, a single leading ant recruits a single follower to an important resource such as a new nest. To examine this process, we used a motorized gantry, which has not previously been used in ant studies, to track tandem running ants accurately in a large arena and we compared their performance in the presence of different types of landmark. We interrupted tandem runs by taking away the leader and moved a large distant landmark behind the new nest just at the time of this separation. Our aim was to determine what information followers might have obtained from the incomplete tandem run they had followed, and how they behaved after the tandem run had been interrupted. Our results show that former followers search by using composite random strategies with elements of sub-diffusive and diffusive movements. Furthermore, when we provided more landmarks former followers searched for longer. However, when all landmarks were removed completely from the arena, the ants' search duration lasted up to four times longer. Hence, their search strategy changes in the presence or absence of landmarks. Even after extensive search of this kind, former followers headed back to their old nest but did not return along the path of the tandem run they had followed. The combination of the position to which the large distant landmark behind the new nest was moved and the presence or absence of additional landmarks influenced the orientation of the former followers' paths back to the old nest. We also found that these ants exhibit behavioural lateralization in which they possibly use their right eye more than their left eye to recognize landmarks for navigation. Our results suggest that former follower ants learn landmarks during tandem running and use this information to make strategic decisions. PMID:24198259

Basari, Norasmah; Bruendl, Aisha C; Hemingway, Charlotte E; Roberts, Nicholas W; Sendova-Franks, Ana B; Franks, Nigel R



Diversity in coding tandem repeats in related Neisseria spp.  

PubMed Central

Background Tandem repeats contained within coding regions can mediate phase variation when the repeated units change the reading frame of the coding sequence in a copy number dependent manner. Coding tandem repeats are those which do not alter the reading frame with copy number, and the changes in copy number of these repeats may then potentially alter the function or antigenicity of the protein encoded. Three complete neisserial genomes were analyzed and compared to identify coding tandem repeats where the number of copies of the repeat will have some structural consequence for the protein. This is the first study to address coding tandem repeats that may affect protein structures using comparative genomics, combined with a population survey to investigate which show interstrain variability. Results A total of 28 genes were identified. Of these, 22 contain coding tandem repeats that vary in copy number between the three sequenced strains, three strain specific genes were included for investigation on the basis of having >90% identity between repeated units, and three genes with repeated elements of >250 bp were included although no length variations were seen in the genomes. Amplification, and sequencing of repeats showing altered copy number, of these 28 coding tandem repeat containing regions, from a set of largely unrelated strains, revealed further repeat length variation in several cases. Conclusion Eighteen genes were identified which have variation in repeat copy number between strains of the same species, twelve of which show greater diversity in repeat copy number than is present in the sequenced genomes. In some cases, this may reflect a mechanism for the generation of antigenic variation, as previously described in other species. However, some of the genes identified encode proteins with cytoplasmic functions, including sugar metabolism, DNA repair, and protein production, in which repeat length variation may have other functions. Coding tandem repeats appear to represent a largely unexplored mechanism of generating diversity in the Neisseria spp. PMID:14611665

Jordan, Philip; Snyder, Lori AS; Saunders, Nigel J



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

PubMed Central

Herein we describe the development and application of a set of novel N, N-dimethyl leucine (DiLeu) 4-plex isobaric tandem mass (MS2) tagging reagents with high quantitation efficacy and greatly reduced cost for neuropeptide and protein analysis. DiLeu reagents serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency. DiLeu reagent resembles the general structure of a tandem mass tag in that it contains an amine reactive group (triazine ester) targeting the N-terminus and ?-amino group of the lysine side-chain of a peptide, a balance group, and a reporter group. A mass shift of m/z 145.1 is observed for each incorporated label. Intense a1 reporter ions at m/z 115.1, 116.1, 117.1, and 118.1 are observed for all pooled samples upon MS2. All labeling reagents are readily synthesized from commercially available chemicals with greatly reduced cost. Labels 117 and 118 can be synthesized in one step and labels 115 and 116 can be synthesized in two steps. Both DiLeu and iTRAQ reagents show comparable protein sequence coverage (~43%) and quantitation accuracy (<15%) for tryptically digested protein samples. Furthermore, enhanced fragmentation of DiLeu labeling reagents offers greater confidence in protein identification and neuropeptide sequencing from complex neuroendocrine tissue extracts from a marine model organism, Callinectes sapidus. PMID:20218596

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



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.



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)



Tandemly repeated pentanucleotides in DNA sequences of eucaryotes.  

PubMed Central

Genetic sequence data banks were scanned in order to retrieve tandemly repeated pentanucleotides (pnts). It was found that among 102 (=(1024-4)/2/5) possible distinct pnts roughly each fourth is involved in tandem repeats. It is shown that tandemly repeated pnts are composed of frequently occurring di- and trinucleotides and that those pnts which occur frequently in the form of mono- or di-pnts form also tandem repeats either in the form of satellites or in the form of shorter tandem repeats. Human satellite III is taken as a specific example. It is shown that the first guanine within GG-AAT pnt exhibits the highest mutability. Sequential distribution of base changes gives evidence that the mutations do not occur at random positions but in a correlated fashion so that long stretches of original pnts remain intact. It is found that pnts related to the satellite III are present in introns and flanking regions of some structural genes, but are not preserved between orthologous genes of related species. The results corroborate the most plausible mechanism of their evolution--rapid amplification followed by successive divergence of repeat units by various mutational processes. PMID:8078778

Borstnik, B; Pumpernik, D; Lukman, D; Ugarkovi?, D; Plohl, M



Selection against tandem splice sites affecting structured protein regions  

PubMed Central

Background Alternative selection of splice sites in tandem donors and acceptors is a major mode of alternative splicing. Here, we analyzed whether in-frame tandem sites leading to subtle mRNA insertions/deletions of 3, 6, or 9 nucleotides are under natural selection. Results We found multiple lines of evidence that the human protein coding sequences are under selection against such in-frame tandem splice events, indicating that these events are often deleterious. The strength of selection is not homogeneous within the coding sequence as protein regions that fold into a fixed 3D structure (intrinsically ordered) are under stronger selection, especially against sites with a strong minor splice site. Investigating structures of functional protein domains, we found that tandem acceptors are preferentially located at the domain surface and outside structural elements such as helices and sheets. Using three-species comparisons, we estimate that more than half of all mutations that create NAGNAG acceptors in the coding region have been eliminated by selection. Conclusion We estimate that ~2,400 introns are under selection against possessing a tandem site. PMID:18366714



Aconitum pseudo-laeve var. erectum inhibits receptor activator of nuclear factor kappa-B ligand-induced osteoclastogenesis via the c-Fos/nuclear factor of activated T-cells, cytoplasmic 1 signaling pathway and prevents lipopolysaccharide-induced bone loss in mice.  


Aconitum pseudo-laeve var. erectum (APE) has been widely shown in herbal medicine to have a therapeutic effect on inflammatory conditions. However, there has been no evidence on whether the extract of APE is involved in the biological bone metabolism process, particularly osteoclast-mediated bone resorption. In this study, we confirmed that the administration of APE could restore normal skeletal conditions in a murine model of lipopolysaccharide (LPS)-induced bone loss via a decrease in the receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin (OPG) ratio and osteoclast number. We then investigated the effect of APE on the RANKL-induced formation and function of osteoclasts to elucidate its underlying molecular mechanisms. APE suppressed the formation of tartrate-resistant acid phosphatase (TRAP)-positive cells, as well as the bone-resorbing activity of mature osteoclasts. Furthermore, APE attenuated nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and c-Fos without affecting any early signal pathway of osteoclastogenesis. Subsequently, APE significantly downregulated the expression of various genes exclusively expressed in osteoclasts. These results demonstrate that APE restores LPS-induced bone loss through a decrease of the serum RANKL/OPG ratio, and inhibits osteoclast differentiation and function, suggesting the promise of APE as a potential cure for various osteoclast-associated bone diseases. PMID:25100255

Baek, Jong Min; Kim, Ju-Young; Cheon, Yoon-Hee; Park, Sun-Hyang; Ahn, Sung-Jun; Yoon, Kwon-Ha; Oh, Jaemin; Lee, Myeung Su



A tandem mirror plasma source for hybrid plume plasma studies  

NASA Technical Reports Server (NTRS)

A tandem mirror device to be considered as a hot plasma source for the hybrid plume rocket concept is discussed. The hot plamsa from this device is injected into an exhaust duct, which will interact with an annular hypersonic layer of neutral gas. The device can be used to study the dynamics of the hybrid plume, and to verify the numerical predictions obtained with computer codes. The basic system design is also geared towards low weight and compactness, and high power density at the exhaust. The basic structure of the device consists of four major subsystems: (1) an electric power supply; (2) a low temperature, high density plasma gun, such as a stream gun, an MPD source or gas cell; (3) a power booster in the form of a tandem mirror machine; and (4) an exhaust nozzle arrangement. The configuration of the tandem mirror section is shown.

Yang, T. F.; Chang, F. R.; Miller, R. H.; Wenzel, K. W.; Krueger, W. A.



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


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.



Specificity and Autoregulation of Notch Binding by Tandem WW Domains in Suppressor of Deltex  

PubMed Central

WW domains target proline-tyrosine (PY) motifs and frequently function as tandem pairs. When studied in isolation, single WW domains are notably promiscuous and regulatory mechanisms are undoubtedly required to ensure selective interactions. Here, we show that the fourth WW domain (WW4) of Suppressor of Deltex, a modular Nedd4-like protein that down-regulates the Notch receptor, is the primary mediator of a direct interaction with a Notch-PY motif. A natural Trp to Phe substitution in WW4 reduces its affinity for general PY sequences and enhances selective interaction with the Notch-PY motif via compensatory specificity-determining interactions with PY-flanking residues. When WW4 is paired with WW3, domain-domain association, impeding proper folding, competes with Notch-PY binding to WW4. This novel mode of autoinhibition is relieved by binding of another ligand to WW3. Such cooperativity may facilitate the transient regulatory interactions observed in vivo between Su(dx) and Notch in the endocytic pathway. The highly conserved tandem arrangement of WW domains in Nedd4 proteins, and similar arrangements in more diverse proteins, suggests domain-domain communication may be integral to regulation of their associated cellular activities. PMID:17656366

Baron, Martin; Golovanov, Alexander P.; Avis, Johanna M.



Network Engineering of Elastic Data Tra#c via Tandem Queueing Network Models  

E-print Network

Network Engineering of Elastic Data Tra#c via Tandem Queueing Network Models A. W. Berger 1 , E. G is long­range dependent. The tandem CQN models are motivated by the following network engineering scenario

Coffman Jr., E. G.


Protein Complexes Characterization in Arabidopsis thaliana by Tandem Affinity Purification Coupled  

E-print Network

237 Chapter 18 Protein Complexes Characterization in Arabidopsis thaliana by Tandem Affinity affinity purification approach followed by mass spectrometry analysis to try to identify and characterize in vivo protein complexes. Key words Arabidopsis thaliana, Protein complexes, Tandem affinity purification

Hirt, Heribert


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.



Design of tandem genes cluster for isoflavone engineering  

Microsoft Academic Search

In this paper, a universal effective novel method of constructing tandem genes cluster for isoflavone engineering was reported.\\u000a A tandem genes cluster CHS-CHI-IFS (rIFS) of secondary metabolites of plant isoflavones was constructed by using the chalcone\\u000a synthase (CHS), chalcone isomerase (CHI), and isoflavone synthase (IFS) (GenBank accession numbers EU526827, EU526829, EU526830)\\u000a in only one recombination with the pET22b vector. The

Xunli Xia; Guangxiao Yang; Guangyuan He



Tandem junction amorphous semiconductor photovoltaic cell  


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

Dalal, Vikram L. (Newark, DE)



Tandem junction amorphous semiconductor photovoltaic cell  


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

Dalal, V.L.



Lithium hydride doped intermediate connector for high-efficiency and long-term stable tandem organic light-emitting diodes.  


Lithium hydride (LiH) is employed as a novel n-dopant in the intermediate connector for tandem organic light-emitting diodes (OLEDs) because of its easy coevaporation with other electron transporting materials. The tandem OLEDs with two and three electroluminescent (EL) units connected by a combination of LiH doped 8-hydroxyquinoline aluminum (Alq3) and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) demonstrate approximately 2-fold and 3-fold enhancement in current efficiency, respectively. In addition, no extra voltage drop across the intermediate connector is observed. Particularly, the lifetime (T75%) in the tandem OLED with two and three EL units is substantially improved by 3.8 times and 7.4 times, respectively. The doping effect of LiH into Alq3, the charge injection, and transport characteristics of LiH-doped Alq3 are further investigated by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoemission spectroscopy (XPS). PMID:25243919

Ding, Lei; Tang, Xun; Xu, Mei-Feng; Shi, Xiao-Bo; Wang, Zhao-Kui; Liao, Liang-Sheng



Characterization of conserved tandem donor sites and intronic motifs required for alternative splicing in corticosteroid receptor genes.  


Alternative splicing events from tandem donor sites result in mRNA variants coding for additional amino acids in the DNA binding domain of both the glucocorticoid (GR) and mineralocorticoid (MR) receptors. We now show that expression of both splice variants is extensively conserved in mammalian species, providing strong evidence for their functional significance. An exception to the conservation of the MR tandem splice site (an A at position +5 of the MR+12 donor site in the mouse) was predicted to decrease U1 small nuclear RNA binding. In accord with this prediction, we were unable to detect the MR+12 variant in this species. The one exception to the conservation of the GR tandem splice site, an A at position +3 of the platypus GRgamma donor site that was predicted to enhance binding of U1 snRNA, was unexpectedly associated with decreased expression of the variant from the endogenous gene as well as a minigene. An intronic pyrimidine motif present in both GR and MR genes was found to be critical for usage of the downstream donor site, and overexpression of TIA1/TIAL1 RNA binding proteins, which are known to bind such motifs, led to a marked increase in the proportion of GRgamma and MR+12. These results provide striking evidence for conservation of a complex splicing mechanism that involves processes other than stochastic spliceosome binding and identify a mechanism that would allow regulation of variant expression. PMID:19819975

Rivers, Caroline; Flynn, Andrea; Qian, Xiaoxiao; Matthews, Laura; Lightman, Stafford; Ray, David; Norman, Michael



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

Microsoft Academic Search

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

Letian Dou; Jingbi You; Jun Yang; Chun-Chao Chen; Youjun He; Seiichiro Murase; Tom Moriarty; Keith Emery; Gang Li; Yang Yang



Creatinine Measurements in 24 h Urine by Liquid Chromatography-Tandem Mass Spectrometry  

E-print Network

Creatinine Measurements in 24 h Urine by Liquid Chromatography-Tandem Mass Spectrometry EUN, Davis, California 95616 A simple, sensitive, and specific liquid chromatography-tandem mass spectrometry chromatography (HPLC) (17­19), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) (20, 21) method. LC

Hammock, Bruce D.


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


Peptide Retention Time Prediction Yields Improved Tandem Mass Spectrum Identification  

E-print Network

Peptide Retention Time Prediction Yields Improved Tandem Mass Spectrum Identification for Diverse, ignoring precursor informa- tion such as peptide retention time (RT). Efforts to exploit peptide RT., 1997; Yates, III, 1998). 1 Abbreviations used in this manuscript include retention time (RT), liquid

Noble, William Stafford


Wake interaction of two disks falling in tandem  

Microsoft Academic Search

The fluid dynamics video illustrates the interaction of two disks falling in tandem at Reynolds number close to 100. Two fluorescent dyes were used to visualize the wake of each body. We can observe that the trailing body accelerates thanks to the entrainment provided by the wake of the leading body and eventually catches up the leadind body. Then, thick

N. Brosse; S. Cazin; P. Ern



Interactions of tandem square cylinders at low Reynolds numbers  

Microsoft Academic Search

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

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



Coordinated production and inspection in a tandem system  

Microsoft Academic Search

We study the coordination of production and quality control in a tandem-queue system. There are two stages, with a single server at stage one that can engage in processing an item, or inspecting the produced item, or staying idle; whereas the second stage represents the aggregate of the rest of the production facility. We focus on the optimal control of

David D. Yao; Shaohui Zheng



Simple tandem DNA repeats and human genetic disease  

SciTech Connect

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

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



Finding Approximate Tandem Repeats in Genomic Zohar Yakhini  

E-print Network

of definitions of approximate tandem repeats. The ideas and methods underlying the algorithm are Agilent Laboratories and Computer Science Department, Technion (zohar Food are not made or distributed for profit or commercial advantage and that copies bear this notice and the full

Shamir, Ron


Finding Approximate Tandem Repeats in Genomic Zohar Yakhini  

E-print Network

of definitions of approximate tandem repeats. The ideas and methods underlying the algorithm are described ( Agilent Laboratories and Computer Science Department, Technion (zohar yakhini@agilent that copies are not made or distributed for profit or commercial advantage and that copies bear this notice

Friedman, Nir


ORIC stripping foil positioner for tandem beam injection  

SciTech Connect

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

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



Tandem metal relay catalysis: from cyclopropene to polysubstituted furan.  


Transmetalation is a key step in traditional coupling reactions. Herein we discuss the most recent progress in the metal-metal relay catalysis based on a transmetalation strategy. An efficient synthetic strategy for the formation of polysubstituted furan derivatives from cyclopropenes based on the tandem metal relay catalysis (TMRC reaction) is summarized. PMID:24962613

Song, Chuanling; Wang, Jianwu; Xu, Zhenghu



Channel grouping techniques in the tandem Banyan switching fabric  

Microsoft Academic Search

With reference to the ATM tandem Banyan switching fabric (TBSF), which is a self-routing output-queued architecture, the concept of channel grouping is investigated according to which packets address a group of network outlets, not a single network outlet. Channel grouping is adopted as a technique to reduce the implementation complexity of the TBSF. In fact by means of the grouping

P. Giacomazzi




Microsoft Academic Search

Vanadyl deoxophy lloerythroetioporphyrins (DPEP) and vanadyl etioporphyrins (ETIO) have been identified in Gato Ridge and Boscan petroleum samples using a combination of isobutane chemical ionization and tandem mass spectrometry. In addition, particular porphyrins such as the C30 vanadyl DPEP and ETIO species were identified in a crude oil containing approximately 500 ppm total porphyrins, with only minimal sample clean-up.

Jennifer S. Brodbelt; R. Graham Cooks; Karl V. Wood; Thomas J. Jackson




E-print Network

should be at least 6 MeV per nucleon, « the coulomb barrier for uranium », for the particles of interest-Tandem foil stripper and a choice of either gas or foil stripper in the terminal. For each stripper maximum respectively. As foil lifetime specially at injected currents of typically 5 à tends to be a severe problem

Paris-Sud XI, Université de


First tandem mass spectrometric measurement of tropospheric ions  

Microsoft Academic Search

Tandem mass spectrometric measurements of naturally occurring tropospheric ions have identified pyridine, methylpyridine, and ethylpyridine as the parent neutral species responsible for ions observed at mass 80, 94, and 108, respectively. High-resolution mass spectra of natural ions observed over an extended mass range are also shown for two field study locations. At one site (Sapelo Island, GA), pyridine and its

F. L. Eisele



Tandem Clusters of Membrane Proteins in Complete Genome Sequences  

E-print Network

of genes coding for membrane proteins was investigated in 16 complete genomes: 4 archaea, 11 bacteria of isolated ATP-binding protein components in the ABC transporters. Possible implications of tandem cluster for the limitation of the sequence similarity search for functional identification. Aurora and Rose (1998) used

Kihara, Daisuke


Diastereoselective tin-free tandem radical additions to 3-formylchromones.  


A tin-free tandem radical addition methodology onto 3-formylchromones is presented. This radical process yields functionalized chromone structures via two carbon-carbon bond-forming steps. These products contain up to three contiguous stereocenters with good to excellent dr's and yields. PMID:21838264

Zimmerman, Jake R; Manpadi, Madhuri; Spatney, Russell; Baker, Aaron



An adaptive approach to denoising tandem mass spectra  

Microsoft Academic Search

In our recently developed denoising method, a linear combination of five features is used to adjust the peak intensities in tandem mass spectra. Although the method shows a promise, the coefficients (weights) of the linear combination were fixed and determined empirically. In this paper, we propose an adaptive approach for estimating these weights. The proposed approach: (1) calculates the score

Wenjun Lin; Fang-Xiang Wu; Jinhon Shi; Jiarui Ding; Wenjun Zhang



Dynamics of tandem bubble interaction in a microfluidic channel  

PubMed Central

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



Multiclass method for antimicrobial analysis in animal feeds by liquid chromatography-tandem mass spectrometry.  


A rapid multiclass method that covers 50 antimicrobials from 13 different families in animal feeds was developed. Samples were extracted using a mixture of methanol, acetonitrile and a McIlvaine buffer combined with sonication. Feed extracts were simply diluted prior to injection, since the clean-up strategies that were tested, based on either solid-phase extraction or dispersive solid-phase extraction, were ineffective at minimizing matrix-related signal suppression/enhancement. Analysis was carried out by liquid chromatography coupled to tandem mass spectrometry using an electrospray ionization source operating in positive and negative modes. For the quantification, matrix-fortified standard calibration curves were used to compensate for matrix effects and losses in sample preparation. The method was validated in-house in pig, poultry and cattle feed matrices and showed satisfactory performance characteristics. Thus, the proposed approach was suitable for application in a routine high-throughput laboratory for the official control of feeds. PMID:23922055

Borràs, S; Companyó, R; Guiteras, J; Bosch, J; Medina, M; Termes, S



Flute instability and the associated radial transport in the tandem mirror with a divertor mirror cell  

SciTech Connect

The flute instability and the associated radial transport are investigated in the tandem mirror with a divertor mirror cell (the GAMMA10 A-divertor) with help of computer simulation, where GAMMA10 is introduced [Inutake et al., Phys. Rev. Lett. 55, 939 (1985)]. The basic equations used in the simulation were derived on the assumption of an axisymmetric magnetic field. So the high plasma pressure in a nonaxisymmetric minimum-B anchor mirror cell, which is important for the flute mode stability, is taken into account by redefining the specific volume of a magnetic field line. It is found that the flute modes are stabilized by the minimum-B magnetic field even with a divertor mirror although its stabilizing effects are weaker than that without the divertor mirror. The flute instability enhances the radial transport by intermittently repeating the growing up and down of the Fourier amplitude of the flute instability in time.

Katanuma, I.; Yagi, K.; Haraguchi, Y.; Ichioka, N.; Masaki, S.; Ichimura, M.; Imai, T. [Plasma Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)



Enhanced oil recovery system  


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)



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. PMID:23861554

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



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.



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.



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.)



Single P-N junction tandem photovoltaic device  


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

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



Single P-N junction tandem photovoltaic device  


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

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



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))



Status of the New Zealand tandem accelerator mass spectrometry facility  

NASA Astrophysics Data System (ADS)

A tandem accelerator mass spectrometry system is being installed at the Institute of Nuclear Sciences, and will become operational this year. Laboratories for 14C dating and low level radioactivity counting have been established here for several years, and the advent of the accelerator technique is expected to widen significantly the scope of investigations using these facilities, as well as open up new research possibilities. Oceanographic and atmospheric studies in particular are seen as fields where accelerator mass spectrometry can be fruitfully employed. The system being developed is similar to that at Zürich, and is based on a type EN tandem Van de Graaff, with magnetic and electrostatic beam analysis, and sequential acceleration of isotopes under computer control. Techniques have been developed for the conversion of carbonaceous material to graphite, for 14C dating, and the extraction of beryllium from sediments for 10Be measurements.

Sparks, R. J.; Wallace, G.; Bartle, C. M.; Coote, G. E.; Ditchburn, R. G.; Lowe, D. C.; McCabe, W. J.; Pohl, K. P.



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


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. PMID:24903681

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



Crux: rapid open source protein tandem mass spectrometry analysis.  


Efficiently and accurately analyzing big protein tandem mass spectrometry data sets requires robust software that incorporates state-of-the-art computational, machine learning, and statistical methods. The Crux mass spectrometry analysis software toolkit ( ) is an open source project that aims to provide users with a cross-platform suite of analysis tools for interpreting protein mass spectrometry data. PMID:25182276

McIlwain, Sean; Tamura, Kaipo; Kertesz-Farkas, Attila; Grant, Charles E; Diament, Benjamin; Frewen, Barbara; Howbert, J Jeffry; Hoopmann, Michael R; Käll, Lukas; Eng, Jimmy K; MacCoss, Michael J; Noble, William Stafford



Interior of elevator tower, Block 31, looking northeast. Otis Tandem ...  

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

Interior of elevator tower, Block 31, looking northeast. Otis Tandem Gearless Elevator Hoist (1941); floor selector (far left), in foreground is the motor generator set which includes exciter (left), AC motor (center), DC generator (right); beyond is the passenger motor (right), hoist cable and drum (center), freight motor (left). - Columbia Basin Project, Grand Coulee Dam & Franklin D. Roosevelt Lake, Across Columbia River, Southeast of Town of Grand Coulee, Grand Coulee, Grant County, WA


Evidence for rolling circle replication of tandem genes in Drosophila  

Microsoft Academic Search

Extrachromosomal circular DNA (eccDNA) is one characteristic of the plasticity of the eukaryotic genome. It is found in various organisms and con- tains sequences derived primarily from repetitive chromosomal DNA. Using 2D gel electrophoresis, we have previously detected eccDNA composed of chromosomal tandem repeats throughout the life cycle of Drosophila. Here, we report for the first time evidence suggesting the

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



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. PMID:19507873

Mukherjee, Sumit; Lee, Daesung



Flexible micromorph tandem aSi\\/?c-Si solar cells  

Microsoft Academic Search

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

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



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



Spurious ionic charge states in a tandem accelerator  

Microsoft Academic Search

Spurious projectiles appearing in a tandem accelerator when tuning highly ionized 35Cl were quantitatively analyzed in an attempt to understand their origin. Most of these ions can be explained in terms of multiple electron-capture and electron-loss reactions of the accelerating particle in the high-energy section of the accelerator. The fair agreement between the experimental yields of different spurious beams and

J. O Fernández Niello; A. Arazi; O. A Capurro; D. Abriola; A. M. J Ferrero; L. Gladkis; R. G Liberman; G. V. Martí; A. J Pacheco; M. Ramírez; J. E Testoni



High efficiency inorganic/organic hybrid tandem solar cells.  


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



Facile synthesis of halogenated spiroketals via a tandem iodocyclization.  


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



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.



Automatic Quality Assessment of Peptide Tandem Mass Spectra  

Microsoft Academic Search

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

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



The mechanics and behavior of cliff swallows during tandem flights.  


Cliff swallows (Petrochelidon pyrrhonota) are highly maneuverable social birds that often forage and fly in large open spaces. Here we used multi-camera videography to measure the three-dimensional kinematics of their natural flight maneuvers in the field. Specifically, we collected data on tandem flights, defined as two birds maneuvering together. These data permit us to evaluate several hypotheses on the high-speed maneuvering flight performance of birds. We found that high-speed turns are roll-based, but that the magnitude of the centripetal force created in typical maneuvers varied only slightly with flight speed, typically reaching a peak of ~2 body weights. Turning maneuvers typically involved active flapping rather than gliding. In tandem flights the following bird copied the flight path and wingbeat frequency (~12.3 Hz) of the lead bird while maintaining position slightly above the leader. The lead bird turned in a direction away from the lateral position of the following bird 65% of the time on average. Tandem flights vary widely in instantaneous speed (1.0 to 15.6 m s(-1)) and duration (0.72 to 4.71 s), and no single tracking strategy appeared to explain the course taken by the following bird. PMID:24855672

Shelton, Ryan M; Jackson, Brandon E; Hedrick, Tyson L



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.



Oak Ridge 25URC tandem accelerator 1994 SNEAP lab report  

SciTech Connect

The 25URC tandem accelerator is still in shut-down mode until the facility is reconfigured to produce radioactive ion beams (RIBs). Again, the authors have operated approximately 200 hours for ion implantation studies in support of RIB development. Operation of the accelerator has been generally very reliable with most problems being associated with power supplies and components located outside the accelerator. The major operational problem this year was the development of internal shorts in the coils of the energy-analyzing magnet which caused beam instability. The major development activity for the tandem accelerator was the replacement of the corona-point voltage-grading system with resistors. Several milestones for the RIB project have been met since SNEAP 1993. The high-voltage platforms have been built and tested at the required 300 kV. Most equipment has been installed on the platforms so that the first beam can be developed using the Mark I target-ion source. This ion source was characterized on the ion source test facility before moving it to the platform. The second-stage mass-separator magnets have been specified and the contract has been awarded to Sigma Phi. The final optics design for the beam line from the second-stage separator to the tandem accelerator is being completed and equipment and controls are being procured.

Alton, G.D.; Dinehart, M.R.; Dowling, D.T. [and others



Tandem Repeat-Containing MITEs in the Clam Donax trunculus  

PubMed Central

Two distinct classes of repetitive sequences, interspersed mobile elements and satellite DNAs, shape eukaryotic genomes and drive their evolution. Short arrays of tandem repeats can also be present within nonautonomous miniature inverted repeat transposable elements (MITEs). In the clam Donax trunculus, we characterized a composite, high copy number MITE, named DTC84. It is composed of a central region built of up to five core repeats linked to a microsatellite segment at one array end and flanked by sequences holding short inverted repeats. The modular composition and the conserved putative target site duplication sequence AA at the element termini are equivalent to the composition of several elements found in the cupped oyster Crassostrea virginica and in some insects. A unique feature of D. trunculus element is ordered array of core repeat variants, distinctive by diagnostic changes. Position of variants in the array is fixed, regardless of alterations in the core repeat copy number. Each repeat harbors a palindrome near the junction with the following unit, being a potential hotspot responsible for array length variations. As a consequence, variations in number of tandem repeats and variations in flanking sequences make every sequenced element unique. Core repeats may be thus considered as individual units within the MITE, with flanking sequences representing a “cassette” for internal repeats. Our results demonstrate that onset and spread of tandem repeats can be more intimately linked to processes of transposition than previously thought and suggest that genomes are shaped by interplays within a complex network of repetitive sequences. PMID:24317975

Satovic, Eva; Plohl, Miroslav



The tandemly repeated domains of a ?-propeller phytase act synergistically to increase catalytic efficiency.  


?-Propeller phytases (BPPs) with tandemly repeated domains are abundant in nature. Previous studies have shown that the intact domain is responsible for phytate hydrolysis, but the function of the other domain is relatively unknown. In this study, a new dual-domain BPP (PhyH) from Bacillus sp. HJB17 was identified to contain an incomplete N-terminal BPP domain (PhyH-DI, residues 41-318) and a typical BPP domain (PhyH-DII, residues 319-644) at the C-terminus. Purified recombinant PhyH and PhyH-DII required Ca(2+) for phytase activity, showed activity at low temperatures (0-35 °C) and pH 6.0-8.0, and remained active (at 37 °C) after incubation at 60 °C and pH 6.0-12.0. Compared with PhyH-DII, PhyH is catalytically more active against phytate (catalytic constant 27.72 versus 4.17 s(-1)), which indicates the importance of PhyH-DI in phytate degradation. PhyH-DI was found to hydrolyze phytate intermediate D-Ins(1,4,5,6) P(4), and to act synergistically (a 1.2-2.5-fold increase in phosphate release) with PhyH-DII, other BPPs (PhyP and 168PhyA) and a histidine acid phosphatase. Furthermore, fusion of PhyH-DI with PhyP or 168PhyA significantly enhanced their catalytic efficiencies. This is the first report to elucidate the substrate specificity of the incomplete domain and the functional relationship of tandemly repeated domains in BPPs. We conjecture that dual-domain BPPs have succeeded evolutionarily because they can increase the amount of available phosphate by interacting together. Additionally, fusing PhyH-DI to a single-domain phytase appears to be an efficient way to improve the activity of the latter. PMID:21707924

Li, Zhongyuan; Huang, Huoqing; Yang, Peilong; Yuan, Tiezheng; Shi, Pengjun; Zhao, Junqi; Meng, Kun; Yao, Bin



LipidBlast - in-silico tandem mass spectrometry database for lipid identification  

PubMed Central

Current tandem mass spectral libraries for lipid annotations in metabolomics are limited in size and diversity. We provide a freely available computer generated in-silico tandem mass spectral library of 212,516 MS/MS spectra covering 119,200 compounds from 26 lipid compound classes, including phospholipids, glycerolipids, bacterial lipoglycans and plant glycolipids. Platform independence is shown 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; Yup Lee, Do; DeFelice, Brian; Meissen, John K.; Fiehn, Oliver



The analysis of trichothecenes in wheat and human plasma samples by chemical ionization tandem mass spectrometry  

Microsoft Academic Search

Ammonia desorption chemical ionization (D\\/CI) tandem mass spectrometry (method A), isobutane D\\/CI tandem mass spectrometry using reactive collisions with ammonia (method B), and gas chromatography negative CI (GC-NCI) tandem mass spectrometry (method C) were compared for the detection and quantitation of trichothecenes in spiked human plasma and wheat samples. The trichothecenes were analyzed as their heptafluorobutyrate (HFB) esters in method

R. Kostiainen; A. Rizzo; A. Hesso



Preprocessing of Tandem Mass Spectrometric Data Based on Decision Tree Classification  

Microsoft Academic Search

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

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



Quantification of endogenous brassinosteroids in sub-gram plant tissues by in-line matrix solid-phase dispersion-tandem solid phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry.  


A matrix solid-phase dispersion (MSPD)-tandem mixed mode anion exchange (MAX)-mixed mode cation exchange (MCX) solid phase extraction-high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method was developed for quantification of six endogenous brassinosteroids (BRs) (24-epibrassinolide, 24-epicastasterone, 6-deoxo-24-epicastasterone, dolichosterone, teasterone and typhasterol) in rice plant tissues. Non-polar interferences were removed effectively by C8 dispersant used in MSPD, while the following tandem MAX-MCX process facilitated the elimination of polar and ionizable compounds. The weak reversed-phase retention feature of MAX-MCX leaded to good compatibility of the elution solvents in the in-line coupled MSPD-MAX-MCX system. This system was optimized for extraction and purification of BRs in plant samples. The effects of the type of solid phase, the elution solvent, the extraction temperature and the clean-up material were studied. Before HPLC separation, BRs purified were derivatized by m-aminophenylboronic acid to enhance the sensitivity of MS/MS to BRs. Compared with traditional liquid-liquid extraction and solid phase extraction (LLE-SPE), the proposed MSPD-MAX-MCX method showed higher extraction efficiency, lower matrix effect, and advantages of easy manipulation and time-saving. The in-line MSPD-MAX-MCX coupled with HPLC-MS/MS method provided a linear response over two orders of magnitude of BRs concentration with correlation coefficients above 0.9982, limits of detection between 0.008 and 0.04ngmL(-1), relative standard deviations (RSDs) below 29.4%, and recoveries above 77.8%. The proposed method has been successfully applied to analysis of endogenous BRs in rice plant at booting stage and maturity stage. PMID:25092597

Wang, Lu; Duan, Chunfeng; Wu, Dapeng; Guan, Yafeng



Optical simulation and optimization of weak-microcavity tandem white organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

We systematically studied the influence of weak microcavity effects on the optical properties of tandem white organic light-emitting diodes (WOLEDs) using optical simulation. Based on the simulation results, an image processing method is developed and verified for rational design of high-performance tandem WOLEDs. The results indicate that low operating voltage, good color rendering index, and angular emission properties can be simultaneously obtained in tandem WOLEDs by engineering the device structure. This study provides promising direction for the development of high-performance tandem WOLEDs.

Yue, Shouzhen; Guo, Runda; Wu, YuKun; Yan, Pingrui; Zhang, Shiming; Zhang, Zhensong; Qu, Dalong; Zhao, Yi



Tandemly repeated DNA families in the mouse genome  

PubMed Central

Background Functional and morphological studies of tandem DNA repeats, that combine high portion of most genomes, are mostly limited due to the incomplete characterization of these genome elements. We report here a genome wide analysis of the large tandem repeats (TR) found in the mouse genome assemblies. Results Using a bioinformatics approach, we identified large TR with array size more than 3 kb in two mouse whole genome shotgun (WGS) assemblies. Large TR were classified based on sequence similarity, chromosome position, monomer length, array variability, and GC content; we identified four superfamilies, eight families, and 62 subfamilies - including 60 not previously described. 1) The superfamily of centromeric minor satellite is only found in the unassembled part of the reference genome. 2) The pericentromeric major satellite is the most abundant superfamily and reveals high order repeat structure. 3) Transposable elements related superfamily contains two families. 4) The superfamily of heterogeneous tandem repeats includes four families. One family is found only in the WGS, while two families represent tandem repeats with either single or multi locus location. Despite multi locus location, TRPC-21A-MM is placed into a separated family due to its abundance, strictly pericentromeric location, and resemblance to big human satellites. To confirm our data, we next performed in situ hybridization with three repeats from distinct families. TRPC-21A-MM probe hybridized to chromosomes 3 and 17, multi locus TR-22A-MM probe hybridized to ten chromosomes, and single locus TR-54B-MM probe hybridized with the long loops that emerge from chromosome ends. In addition to in silico predicted several extra-chromosomes were positive for TR by in situ analysis, potentially indicating inaccurate genome assembly of the heterochromatic genome regions. Conclusions Chromosome-specific TR had been predicted for mouse but no reliable cytogenetic probes were available before. We report new analysis that identified in silico and confirmed in situ 3/17 chromosome-specific probe TRPC-21-MM. Thus, the new classification had proven to be useful tool for continuation of genome study, while annotated TR can be the valuable source of cytogenetic probes for chromosome recognition. PMID:22035034



Moral Enhancement  

PubMed Central

Opponents of biomedical enhancement often claim that, even if such enhancement would benefit the enhanced, it would harm others. But this objection looks unpersuasive when the enhancement in question is a moral enhancement — an enhancement that will expectably leave the enhanced person with morally better motives than she had previously. In this article I (1) describe one type of psychological alteration that would plausibly qualify as a moral enhancement, (2) argue that we will, in the medium-term future, probably be able to induce such alterations via biomedical intervention, and (3) defend future engagement in such moral enhancements against possible objections. My aim is to present this kind of moral enhancement as a counter-example to the view that biomedical enhancement is always morally impermissible. PMID:19132138

Douglas, Thomas



Detection of efaproxiral (RSR13) and its metabolites in equine by liquid chromatography tandem mass spectrometry.  


Efaproxiral (RSR 13) is an experimental synthetic allosteric modifier of haemoglobin (Hb) that acts by increasing the release of oxygen from Hb to the surrounding tissues. It has been shown to increase maximum oxygen uptake (VO(2max)) in a canine skeletal muscle model. The ability to increase maximal muscle oxygen uptake makes efaproxiral a potential performance-enhancing agent and is therefore prohibited by the World Anti-Doping Agency. In this study, a method for the detection and elimination of efaproxiral in equine plasma and urine after a 2.5?g intravenous administration of efaproxiral is described. Post administration plasma and urine samples were collected up to 120?h. Efaproxiral was detected up to 120?h in urine and up to 78?h in plasma. In plasma, the peak concentration was 42?µg/ml and detected at 5?min post administration. In urine, the peak concentration was 2.8?mg/ml and detected at 0-1?h post administration. A validated liquid chromatography tandem mass spectrometry method was used for the quantitation of efaproxiral in equine plasma and urine. The limit of detection of the method is 0.05?ng/ml in plasma and 0.1?ng/ml in urine. The method is highly sensitive and specific with good precision, accuracy and recovery. The manuscript also describes the systematic identification of efaproxiral metabolites detected in post administration equine urine samples. The metabolites were identified by use of enhanced mass spectra and enhanced product ion scans. Both positive and negative mode ionizations were utilized for metabolite identification and plausible fragmentation pathways were proposed for the phase 1 metabolite identified. In addition to free efaproxiral, one phase 1 metabolite and two phase 2 metabolites were identified in post administration urine. PMID:24446264

Yi, Rong; Sandhu, Jasmeet; Zhao, Sarah; Lam, Geoffrey; Loganathan, Devan; Morrissey, Barbara



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

ERIC Educational Resources Information Center

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

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



Analyzing Proteomes and Protein Function Using Graphical Comparative Analysis of Tandem Mass Spectrometry Results  

Microsoft Academic Search

Although generating large amounts of proteomic data us- ing tandem mass spectrometry has become routine, there is currently no single set of comprehensive tools for the rigorous analysis of tandem mass spectrometry results given the large variety of possible experimental aims. Cur- rently available applications are typically designed for dis- playing proteins and posttranslational modifications from the point of view

K. Jill McAfee; Dexter T. Duncan; Michael Assink; Andrew J. Link



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. PMID:23363705



Assigning Significance to Peptides Identified by Tandem Mass Spectrometry Using Decoy Databases  

E-print Network

Assigning Significance to Peptides Identified by Tandem Mass Spectrometry Using Decoy Databases, Washington 98195 Received September 18, 2007 Automated methods for assigning peptides to observed tandem mass spectra typically return a list of peptide-spectrum matches, ranked according to an arbitrary score

Storey, John D.


Assessing the fraction of short-distance tandem splice sites under purifying selection  

PubMed Central

Many alternative splice events result in subtle mRNA changes, and most of them occur at short-distance tandem donor and acceptor sites. The splicing mechanism of such tandem sites likely involves the stochastic selection of either splice site. While tandem splice events are frequent, it is unknown how many are functionally important. Here, we use phylogenetic conservation to address this question, focusing on tandems with a distance of 3–9 nucleotides. We show that previous contradicting results on whether alternative or constitutive tandem motifs are more conserved between species can be explained by a statistical paradox (Simpson's paradox). Applying methods that take biases into account, we found higher conservation of alternative tandems in mouse, dog, and even chicken, zebrafish, and Fugu genomes. We estimated a lower bound for the number of alternative sites that are under purifying (negative) selection. While the absolute number of conserved tandem motifs decreases with the evolutionary distance, the fraction under selection increases. Interestingly, a number of frameshifting tandems are under selection, suggesting a role in regulating mRNA and protein levels via nonsense-mediated decay (NMD). An analysis of the intronic flanks shows that purifying selection also acts on the intronic sequence. We propose that stochastic splice site selection can be an advantageous mechanism that allows constant splice variant ratios in situations where a deviation in this ratio is deleterious. PMID:18268022

Hiller, Michael; Szafranski, Karol; Sinha, Rileen; Huse, Klaus; Nikolajewa, Swetlana; Rosenstiel, Philip; Schreiber, Stefan; Backofen, Rolf; Platzer, Matthias



Tandem 1;30 translocation: a new structural abnormality in the horse (Equus caballus)  

Microsoft Academic Search

A 1;30 tandem translocation was found in an 8-yr-old thoroughbred stallion referred because of reduced fertility. The diagnosis was confirmed by GTG and CBG staining. This is the first report of a tandem translocation in the horse.Copyright © 1996 S. Karger AG, Basel

S. E. Long



In-terminal ECR Ion Source of the Tandem Accelerator at JAERI  

Microsoft Academic Search

Modern electron cyclotron resonance ion source (ECRIS)s are able to produce intense beams of highly charged positive ions, of which charge states are higher than those obtained from electron stripping at the high voltage terminal of tandem accelerators. It is possible to increase beam intensity, beam energy and beam species by utilizing an ECRIS in a tandem accelerator. A small

SUPER NANOGAN; M. Matsuda; C. Kobayashi; S. Takeuchi


Origin and Evolution of Tandem Repeats in the Mitochondrial DNA Control Region of Shrikes (Lanius spp.)  

Microsoft Academic Search

The origin and evolution of a 128-bp tandem repeat in the mtDNA control region of shrikes ( Lanius: Aves) were investigated. The tandem repeat is present in only two species, L. excubitor and L. ludovicianus. In contrast to the variation in repeat number in L. ludovicianus, all individuals of three subspecies of L. excubitor had three repeats. Comparative analysis suggests

Nicholas I. Mundy; Andreas J. Helbig



Structural Properties of DNA Oligomers Containing (GACX)n and (GAXC)n Tandem Repeats  

E-print Network

to as Triplet Expansion diseases.1�5 Prior research on the repeat sequences (CAG.CTG, CGG.CCG, GAA.TTC, etcStructural Properties of DNA Oligomers Containing (GACX)n and (GAXC)n Tandem Repeats Indrani at biopolymers@wiley. com INTRODUCTION S hort tandem repeats and DNA microsatellites are common in the human

Fox, George


Automated approach for quantitative analysis of complex peptide mixtures from tandem mass spectra  

Microsoft Academic Search

To take advantage of the potential quantitative benefits offered by tandem mass spectrometry, we have modified the method in which tandem mass spectrum data are acquired in 'shotgun' proteomic analyses. The proposed method is not data dependent and is based on the sequential isolation and fragmentation of precursor windows (of 10 m\\/z) within the ion trap until a desired mass

John D Venable; Meng-Qiu Dong; James Wohlschlegel; Andrew Dillin; John R Yates



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



Processing of tandem mass spectrometric data based on decision tree classification  

Microsoft Academic Search

We present a processing method for Q-TOF tandem mass spectra to increase the accuracy of database searching for peptide (protein) identification. Based on the natural isotopic information inherent in tandem mass spectra, we construct a decision tree after feature selection to classify the noise and ions' peaks. Furthermore, we recognize overlapping peaks to find the monoisotopic masses of ions for

Jingfen Zhang; Simin He; Jinjin Cai; Xingjun Cao; Ruixiang Sun; Yan Fu; Rong Zeng; Wen Gao


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



A Tandem-electrostatic-quadrupole for accelerator-based BNCT  

NASA Astrophysics Data System (ADS)

A project to develop a Tandem-electrostatic-quadrupole (TESQ) accelerator for accelerator-based boron neutron capture therapy (AB-BNCT) is described. A folded Tandem, with 1.25 MV terminal voltage, combined with an electrostatic quadrupole (ESQ) chain is being proposed. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the 7Li(p, n) 7Be reaction slightly beyond its resonance at 2.25 MeV. This machine is conceptually shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the 7Li(p, n) 7Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. This electrostatic machine is the technologically simplest and cheapest solution for optimized AB-BNCT.

Kreiner, A. J.; Kwan, J. W.; Burlón, A. A.; Di Paolo, H.; Henestroza, E.; Minsky, D. M.; Valda, A. A.; Debray, M. E.; Somacal, H.



Sorting by reversals, block interchanges, tandem duplications, and deletions  

PubMed Central

Background Finding sequences of evolutionary operations that transform one genome into another is a classic problem in comparative genomics. While most of the genome rearrangement algorithms assume that there is exactly one copy of each gene in both genomes, this does not reflect the biological reality very well – most of the studied genomes contain duplicated gene content, which has to be removed before applying those algorithms. However, dealing with unequal gene content is a very challenging task, and only few algorithms allow operations like duplications and deletions. Almost all of these algorithms restrict these operations to have a fixed size. Results In this paper, we present a heuristic algorithm to sort an ancestral genome (with unique gene content) into a genome of a descendant (with arbitrary gene content) by reversals, block interchanges, tandem duplications, and deletions, where tandem duplications and deletions are of arbitrary size. Conclusion Experimental results show that our algorithm finds sorting sequences that are close to an optimal sorting sequence when the ancestor and the descendant are closely related. The quality of the results decreases when the genomes get more diverged or the genome size increases. Nevertheless, the calculated distances give a good approximation of the true evolutionary distances. PMID:19208182

Bader, Martin



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. PMID:24895098

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



The first tandem, all-exciplex-based WOLED.  


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



The First Tandem, All-exciplex-based WOLED  

NASA Astrophysics Data System (ADS)

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



Theoretical and experimental investigation on tandem Theoretical and experimental investigation on tandem modulator configurations for Frequency Coded Quantum Key Distribution systems  

Microsoft Academic Search

We have theoretically and experimentally address the possible tandem electro-optical modulator configurations that can be employed to implement Frequency Coded Quantum Key Distribution systems (FC-QKD). A closed and general formulation of the end to end field propagation in a dispersion compensated FC-QKD optical fiber system under the low modulation index regime is presented which accounts for all the possible tandem

J. Mora; A. Ruiz-Alba; W. Amaya; V. Garcia-Munoz; J. Capmany



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

SciTech Connect

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



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


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)



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


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)



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


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.



Beyond Junk-Variable Tandem Repeats as Facilitators of Rapid Evolution of Regulatory and Coding Sequences  

PubMed Central

Copy Number Variations (CNVs) and Single Nucleotide Polymorphisms (SNPs) have been the major focus of most large-scale comparative genomics studies to date. Here, we discuss a third, largely ignored, type of genetic variation, namely changes in tandem repeat number. Historically, tandem repeats have been designated as non functional “junk” DNA, mostly as a result of their highly unstable nature. With the exception of tandem repeats involved in human neurodegenerative diseases, repeat variation was often believed to be neutral with no phenotypic consequences. Recent studies, however, have shown that as many as 10% to 20% of coding and regulatory sequences in eukaryotes contain an unstable repeat tract. Contrary to initial suggestions, tandem repeat variation can have useful phenotypic consequences. Examples include rapid variation in microbial cell surface, tuning of internal molecular clocks in flies and the dynamic morphological plasticity in mammals. As such, tandem repeats can be useful functional elements that facilitate evolvability and rapid adaptation. PMID:24704980

Gemayel, Rita; Cho, Janice; Boeynaems, Steven; Verstrepen, Kevin J.



Origin and evolution of tandem repeats in the mitochondrial DNA control region of shrikes (Lanius spp.).  


The origin and evolution of a 128-bp tandem repeat in the mtDNA control region of shrikes (Lanius: Aves) were investigated. The tandem repeat is present in only two species, L. excubitor and L. ludovicianus. In contrast to the variation in repeat number in L. ludovicianus, all individuals of three subspecies of L. excubitor had three repeats. Comparative analysis suggests that a short direct repeat, and a secondary structure including the tandem repeat and a downstream inverted repeat, may be important in the origin of the tandem repeat by slipped-strand mispairing and its subsequent turnover. Homogenization of repeat sequences is most simply explained by expansion and contraction of the repeat array. Surprisingly, mtDNA sequences from L. excubitor were found to be paraphyletic with respect to L. ludovicianus. These results show the utility of a comparative analysis for insights into the evolutionary dynamics of mtDNA tandem repeats. PMID:15486698

Mundy, Nicholas I; Helbig, Andreas J



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. PMID:20881002

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



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

Federal Register 2010, 2011, 2012, 2013

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



Behavior of the plasma in the anchor cell of the GAMMA 10 tandem mirror  

SciTech Connect

Anchor cells of the GAMMA 10 tandem mirror are composed of minimum-B magnetic field configuration. Behavior of the plasma in the anchor cell is studied using puffing gas flow rate (PGFR) modulation and by covering some parts of the flux tube of each anchor cell by conducting plates (APs). Ambient neutral pressure is decreased by PGFR modulation during axial/potential confinement in both cases without and with APs and it is found that both line density (nl{sub EA}) and diamagnetism (dm{sub EA}) of the anchor cell plasma increase. Lower neutral pressure in the minimum-B region is investigated during the floated APs and significant improvement of the GAMMA 10 plasma parameters is observed. Possible explanations of the experimental results are given from the viewpoint of ambient neutral pressure oriented anchor plasma behavior. Probable reasons of enhanced ambient neutral pressure in the anchor cell and adverse effects of these neutrals on GAMMA 10 plasma parameters are also pointed out.

Islam, Md. Khairul; Nakashima, Yousuke; Higashizono, Yuta; Cho, Teruji [Plasma Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)



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)



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. PMID:20379812

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



Determination of thyroid hormones and their metabolites in tissue using SPE UPLC-tandem MS.  


A solid-phase liquid chromatography tandem mass spectrometry (SPE LC-MS/MS) method was developed to determine thyroid hormones and their metabolites in tissue samples. The separation was achieved using reversed-phase ultra-performance liquid chromatography (UPLC); the mass spectrometric detection was achieved by positive electrospray ionization and multiple reaction monitoring. Prior to the UPLC separation a sample cleanup with a cation exchange was performed. ¹³C? labeled internal standards were used for the thyroid hormones and their metabolites. The method was linear over a range from 0.23 to 90?nmol/L for thyroxine and from 0.23 to 9?nmol/L for the metabolites. The lower limit of quantification ranged from 0.98 to 1.73?pg on column. Intra- and total assay variation were <10 and <15%, respectively. This method enables us to link thyroid hormone tissue concentrations to local iodothyronine deiodinase expressions, which will enhance our understanding of the regulation of thyroid hormone metabolism on the tissue level. PMID:21877326

Ackermans, M T; Kettelarij-Haas, Y; Boelen, A; Endert, E



Effects of tandem and colliding shock waves on the initiation of triaminotrinitrobenzene  

NASA Astrophysics Data System (ADS)

The shock initiation of the insensitive high-explosive LX-17, which contains 92.5% triaminotrinitrobenzene and 7.5% Kel-F binder, was studied under simulated accident conditions in which two shock waves interact producing locally high pressures and temperatures. Two experimental geometries were studied using embedded manganin pressure gauges to measure the increases in pressure due to exothermic reaction at various locations as functions of time. These pressure histories were compared to ignition and growth reactive flow model calculations to determine whether a second shock compression of reacting LX-17 caused unusually rapid reaction rates and thus more extreme hazards. One experiment used a tandem flyer plate of aluminum and steel separated by a gap to shock the LX-17 charge, allow it to rarify, and then reshock the damaged charge to even higher pressures. These experiments revealed no significant enhancement of the LX-17 reaction rates under this shock, rarefaction, and reshock loading. The second experiment used a grooved flyer plate to produce a subcritical shock wave in LX-17, which then diverged and collided, producing a Mach stem interaction at the charge axis. The threshold conditions under which the Mach stem grew to detonation were measured. The standard LX-17 ignition and growth model yielded excellent agreement with the pressure gauge records in the Mach stem interaction region. The formation of Mach stem interactions by nearly simultaneous multiple high-velocity impacts was identified as a serious shock initiation hazard for heterogeneous solid explosives.

Tarver, Craig M.; Urtiew, Paul A.; Tao, William C.



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.



The tandem repeats enabling reversible switching between the two phases of ?-lactamase substrate spectrum.  


Expansion or shrinkage of existing tandem repeats (TRs) associated with various biological processes has been actively studied in both prokaryotic and eukaryotic genomes, while their origin and biological implications remain mostly unknown. Here we describe various duplications (de novo TRs) that occurred in the coding region of a ?-lactamase gene, where a conserved structure called the omega loop is encoded. These duplications that occurred under selection using ceftazidime conferred substrate spectrum extension to include the antibiotic. Under selective pressure with one of the original substrates (amoxicillin), a high level of reversion occurred in the mutant ?-lactamase genes completing a cycle back to the original substrate spectrum. The de novo TRs coupled with reversion makes a genetic toggling mechanism enabling reversible switching between the two phases of the substrate spectrum of ?-lactamases. This toggle exemplifies the effective adaptation of de novo TRs for enhanced bacterial survival. We found pairs of direct repeats that mediated the DNA duplication (TR formation). In addition, we found different duos of sequences that mediated the DNA duplication. These novel elements-that we named SCSs (same-strand complementary sequences)-were also found associated with ?-lactamase TR mutations from clinical isolates. Both direct repeats and SCSs had a high correlation with TRs in diverse bacterial genomes throughout the major phylogenetic lineages, suggesting that they comprise a fundamental mechanism shaping the bacterial evolution. PMID:25233343

Yi, Hyojeong; Song, Han; Hwang, Junghyun; Kim, Karan; Nierman, William C; Kim, Heenam Stanley



Endothelial cell adhesion in real time. Measurements in vitro by tandem scanning confocal image analysis.  

PubMed Central

Real time measurements of cell-substratum adhesion in endothelial cells were obtained by tandem scanning confocal microscopy of sites of focal contact (focal adhesions) at the abluminal cell surface. Focal contact sites were sharply defined (low radiance levels) in the living cell such that the images could be enhanced, digitized, and isolated from other cellular detail. Sites of focal contact are the principal determinant of cell-substratum adhesion. Measurements of (a) the focal contact area and (b) the closeness of contact (inverse radiance) were used to nominally define the adhesion of a single cell or field of cells, and to record spontaneous and induced changes of cell adhesion in real time. The topography of focal contacts was estimated by calculating separation distances from radiance values using a calibration technique based on interference ring optics. While slightly closer contact was noted between the cell membrane and substratum at or near the center of each focal contact, separation distances throughout the adhesion regions were always < 50 nm. Subtraction of consecutive images revealed continuous spontaneous remodeling of individual focal adhesions in unperturbed cells during periods of < 1 min. Despite extensive remodeling of focal contact sites, however, cell adhesion calculated for an entire cell over extended periods varied by < 10%. When cytoskeletal stability was impaired by exposure to cytochalasin or when cells were exposed to proteolytic enzyme, endothelial adhesion declined rapidly. Such changes were recorded at the level of single cells, groups of cells, and at single focal adhesions. In both unperturbed and manipulated cells, the dynamics of remodeling and cell adhesion characteristics varied greatly between individual sites within the same cell; disappearance of existing sites and appearance of new ones often occurred within minutes while adjacent sites underwent minimal remodelling. Tandem scanning confocal microscopy image analysis of living cells in real time provides repetitive spatial, temporal, and quantitative information about cell adhesion. Such an approach should allow more precise quantitative analyses to be made of the interactions between extracellular matrix, adhesion proteins, integrins, and the cytoskeleton in the living cell. Images PMID:8514872

Davies, P F; Robotewskyj, A; Griem, M L



An RF heated tandem mirror plasma propulsion study  

SciTech Connect

Experimental results on a tandem mirror hybrid plume rocket involving a three-stage system of plasma injection, heating, and subsequent injection through a magnetic nozzle are presented. In the experiments, a plasma is created by breaking down the gas with electron cyclotron resonance heating at 2 kW in the central cell, and the ion species is then heated to high temperatures with ion cyclotron resonance heating at 10 kW in the end cell. A Langmuir probe measured an electron density of 2.5 x 10 to the 16th/cu m and a temperature of 100 eV in the central cell and an ion density of 1.25 x 10 to the 17th/cu m and a temperature of 500 eV in the end cell. 6 refs.

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



Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations  

NASA Technical Reports Server (NTRS)

Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.



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.



Physics issues in mirror and tandem mirror systems  

SciTech Connect

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

Post, R.F.



Molecular ion stability and populations in tandem accelerator mass spectrometry  

NASA Astrophysics Data System (ADS)

The success of tandem accelerator mass spectrometry (AMS) rests, in part, on the dissociation of interfering molecular species in high charge states. Previous work in this laboratory has detected persistent molecules of B 3+2. Molecular orbital calculations suggest that the molecular ion is bound in an excited state, but unbound in the ground state. Other binary homonuclear and heteronuclear ions have been examined theoretically, and AlO 3+ appears to be bound in the ground state. In the present work, experimental determination of the relative abundance, dissociation cross section in the stripper gas and the charge fraction branching ratios for the atomic fragments of B 2 are presented. These results permit an assessment of the expected background levels to be encountered in the application of AMS to stable isobar mass spectrometry.

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



Tandem affinity purification vectors for use in gram positive bacteria.  


Tandem affinity purification has become a valuable tool for the isolation of protein complexes. Here we describe the construction and use of a series of plasmid vectors for Gram positive bacteria. The vectors utilize the SPA tag as well as variants containing a 3C rather than the TEV protease site as 3C protease has been shown to work efficiently at the low temperatures (4 degrees C) used to isolate protein complexes. In addition, a further vector incorporates a GST moiety in place of the 3xFLAG of the SPA tag which provides an additional tagging option for situations where SPA binding may be inefficient. The vectors are all compatible with previously constructed fluorescent protein fusion vectors enabling construction of a suite of affinity and fluorescently tagged genes using a single PCR product. PMID:18093654

Yang, Xiao; Doherty, Geoff P; Lewis, Peter J



First tandem mass spectrometric measurement of tropospheric ions  

NASA Astrophysics Data System (ADS)

Tandem mass spectrometric measurements of naturally occurring tropospheric ions have identified pyridine, methylpyridine, and ethylpyridine as the parent neutral species responsible for ions observed at mass 80, 94, and 108, respectively. High-resolution mass spectra of natural ions observed over an extended mass range are also shown for two field study locations. At one site (Sapelo Island, GA), pyridine and its homologues dominated the positive spectrum. At Mount Evans, CO, the second site, pyridine along with a large number of more massive and presumably very alkali species were observed to dominate the positive spectrum. In addition, X-ray-produced ion spectra were also measured and used to make rough estimates of the pyridine concentrations at the Sapelo site (about 10 ppt) and the total concentration of alkali compounds, excluding NH3, at Mount Evans (about 0.5 ppb).

Eisele, F. L.



Drift-pump coil design for a tandem mirror reactor  

SciTech Connect

This paper describes both the theory and mechanical design behind a new concept for trapped ion removal from tandem mirror end plugs. The design has been developed for the Mirror Advanced Reactor Study (MARS). The new drift-pump coils replace charge-exchange pump beams. Pump beams consume large amounts of power and seriously reduce reactor performance. Drift-pump coils consume only a few megawatts of power and introduce no added burden to the reactor vacuum pumps. In addition, they are easy to replace. The coils are similar in shape to a paper clip and are located at two positions in each end plug. The coils between the transition coil and the first anchor yin-yang serve to remove ions trapped in the magnetic well just outboard of the high field choke coil. The coils located between the anchor coil set and the plug coil set remove sloshing ions and trapped cold ions from the plug region.

Logan, B.G.; Neef, W.S.



Tandem photovoltaic cell using a thin-film polymer electrolyte  

SciTech Connect

A tandem photovoltaic cell has been fabricated using a thin-film plastic electrolyte to connect in optical and electrical series an n-type CdS thin-film and a p-type CdTe single crystal. The electrolyte was a thin film of poly(ethylene oxide) with a polysulfide redox couple. An open circuit voltage of 625 mV and a short-circuit current of 35 mA/cm/sup 2/ were obtained under illumination of 100 mW/cm/sup 2/ with a xenon lamp. The cell output in the present configuration is limited by the series resistance and insufficient band bending in the semiconductor electrodes due to unfavorable resistance matching of the components.

Skotheim, T.



Nonambipolar radial particle transport in a tandem mirror  

SciTech Connect

Nonambipolar transport has been measured in the tandem mirror TMX-U (Phys. Rev. Lett. 53, 783 (1984)) by applying charge conservation to the measured electron currents to the end walls. The resulting confinement time tau/sub perpendicular/ is found to depend upon the central-cell potential phi approximately as tau/sub perpendicular/(msec) = 3phi(kV)/sup -2/. The transport rate, deduced from the data, agrees to within a factor of 1--5 with resonant-transport theory applied to the measured plasma parameters. Attempts to include radial effects by modeling the plasma self-consistently using resonant transport are less successful; near the axis the transport coefficients become too small to explain the equilibrium. Modeling using an ad hoc phi/sup -2/ law for the transport coefficients is more successful.

Hooper E.B. Jr.; Cohen, R.H.; Correll, D.L.; Gilmore, J.M.; Grubb, D.P.



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


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. PMID:22753023

Liang, Tong; Fan, Xiaodan; Li, Qiwei; Li, Shuo-Yen R



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. PMID:22753023

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



Digital Subtraction Fluoroscopic System With Tandem Video Processing Units  

NASA Astrophysics Data System (ADS)

A real-time digital fluoroscopic system utilizing two video processing units (Quantex) in tandem to produce continuous subtraction images of peripheral and internal vessels following intravenous contrast media injection has been inves-tigated. The first processor subtracts a mask image consisting of an exponentially weighted moving average of N1 frames (N1 = 2k where k = 0.7) from each incoming video frame, divides by N1, and outputs the resulting difference image to the second processor. The second unit continuously averages N2 incoming frames (N2 = 2k) and outputs to a video monitor and analog disc recorder. The contrast of the subtracted images can be manipulated by changing gain or by a non-linear output transform. After initial equipment adjustments, a subtraction sequence can be produced without operator interaction with the processors. Alternatively, the operator can freeze the mask and/or the subtracted output image at any time during the sequence. Raw data is preserved on a wide band video tape recorder permitting retrospective viewing of an injection sequence with different processor settings. The advantage of the tandem arrangement is that it has great flexibility in varying the duration and the time of both the mask and injection images thereby minimizing problems of registration between them. In addition, image noise is reduced by compiling video frames rather than by using a large radiation dose for a single frame, which requires a wide dynamic range video camera riot commonly available in diagnostic x-ray equipment. High quality subtraction images of arteries have been obtained in 15 anesthetized dogs using relatively low exposure rates (10-12 ?R/video frame) modest volumes of contrast medium (0.5-1 ml/kg), and low injection flow rates (6-10 ml/sec). The results/ achieved so far suggest that this system has direct clinical applications.

Gould, Robert G.; Lipton, Martin J.; Mengers, Paul; Dahlberg, Roger



Ethnic Variation in the Thymidylate Synthase Enhancer Region Polymorphism among Caucasian and Asian Populations  

Microsoft Academic Search

Thymidylate synthase (TS) regulates the production of DNA synthesis precursors and is an important target of cancer chemotherapy. A tandem repeat sequence in a TS promoter enhancer region (TSER) was recently identified. Polymorphic variation affected in vitro expression levels of the gene. We evaluated the influence of ethnicity on TSER genotype. Allele frequency was similar in Caucasian and Southwest Asian

Sharon Marsh; Elaina S. R. Collie-Duguid; Tao Li; Xiehe Liu; Howard L. McLeod



An approach for configuring space photovoltaic tandem arrays based on cell layer performance  

NASA Technical Reports Server (NTRS)

Meeting solar array performance goals of 300 W/Kg requires use of solar cells with orbital efficiencies greater than 20 percent. Only multijunction cells and cell layers operating in tandem produce this required efficiency. An approach for defining solar array design concepts that use tandem cell layers involve the following: transforming cell layer performance at standard test conditions to on-orbit performance; optimizing circuit configuration with tandem cell layers; evaluating circuit sensitivity to cell current mismatch; developing array electrical design around selected circuit; and predicting array orbital performance including seasonal variations.

Flora, C. S.; Dillard, P. A.



Temperature Behavior in a Tandem Type of Modulated Induction Thermal Plasma for Materials Processings  

NASA Astrophysics Data System (ADS)

A tandem type of modulated induction thermal plasma (Tandem-MITP) system has been developed using two rf power supplies and two coils for one plasma torch. This system was developed to control temperature and reaction fields temporally and spatially in a thermal plasma. The modulation of each coil current can change the thermal plasma temperature in the torch temporally and spatially. Time variation of Ar excitation temperature was estimated by the two-line method using Ar atomic lines. The Tandem-MITP could be established successfully, and the Ar excitation temperature in the thermal plasma could be controlled temporally and spatially by the developed system.

Kuraishi, Katsuya; Akao, Mika; Tanaka, Yasunori; Uesugi, Yoshihiko; Ishijima, Tatsuo



Expansion of stochastic expression repertoire by tandem duplication in mouse Protocadherin-? cluster  

PubMed Central

Tandem duplications are concentrated within the Pcdh cluster throughout vertebrate evolution and as copy number variations (CNVs) in human populations, but the effects of tandem duplication in the Pcdh cluster remain elusive. To investigate the effects of tandem duplication in the Pcdh cluster, here we generated and analyzed a new line of the Pcdh cluster mutant mice. In the mutant allele, a 218-kb region containing the Pcdh-?2 to Pcdh-?c2 variable exons with their promoters was duplicated and the individual duplicated Pcdh isoforms can be disctinguished. The individual duplicated Pcdh-? isoforms showed diverse expression level with stochastic expression manner, even though those have an identical promoter sequence. Interestingly, the 5?-located duplicated Pcdh-?c2, which is constitutively expressed in the wild-type brain, shifted to stochastic expression accompanied by increased DNA methylation. These results demonstrate that tandem duplication in the Pcdh cluster expands the stochastic expression repertoire irrespective of sequence divergence. PMID:25179445

Kaneko, Ryosuke; Abe, Manabu; Hirabayashi, Takahiro; Uchimura, Arikuni; Sakimura, Kenji; Yanagawa, Yuchio; Yagi, Takeshi



Improving Tandem Mass Spectrum Identification Using Peptide Retention Time Prediction across  

E-print Network

Improving Tandem Mass Spectrum Identification Using Peptide Retention Time Prediction across but rarely exploited is peptide chromato- graphic retention time. Efforts to use chromatographic retention time to improve peptide identification are com- plicated because of the variability of retention time

Noble, William Stafford


Progress towards the synthesis of tetracyclic heteroaromatic compounds via tandem benzannulation-cyclization strategies  

E-print Network

A tandem benzannulation-cyclization strategy was successfully applied to the synthesis of a tetracyclic heteroaromatic compound expected to have interesting electronic properties. Benzannulation of a diazo ketone and a ...

Mamaliga, Galina



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

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Common line, traffic-sensitive, and tandem-switched...COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) ACCESS CHARGES Pricing Flexibility § 69.713 Common line, traffic-sensitive, and...



Low driving voltage simplified tandem organic light-emitting devices by using exciplex-forming hosts  

NASA Astrophysics Data System (ADS)

Tandem organic light-emitting devices (OLEDs), i.e., OLEDs containing multiple electroluminescence (EL) units that are vertically stacked, are attracting significant interest because of their ability to realize high current efficiency and long operational lifetime. However, stacking multiple EL units in tandem OLEDs increases driving voltage and complicates fabrication process relative to their standard single unit counterparts. In this paper, we demonstrate low driving voltage tandem OLEDs via utilizing exciplex-forming hosts in the EL units instead of conventional host materials. The use of exciplex-forming hosts reduces the charge injection barriers and the trapping of charges on guest molecules, resulting in the lower driving voltage. The use of exciplex-forming hosts also allows using fewer layers, hence simpler EL configuration which is beneficial for reducing the fabrication complexity of tandem OLEDs.

Zhou, Dong-Ying; Cui, Lin-Song; Zhang, Ying-Jie; Liao, Liang-Sheng; Aziz, Hany



Tandem benzannulation-ring closing metathesis strategy for the synthesis of benzo-fused nitrogen heterocycles ;  

E-print Network

A tandem benzannulation-ring closing metathesis strategy for the efficient synthesis of benzo-fused nitrogen heterocycles such as dihydroquinolines, benzazepines, and benzazocines has been developed. This strategy is based ...

Mak, Xiao Yin



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....


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

SciTech Connect

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

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



Tandem voice communications: digital cellular, VoIP, and voice over Wi-Fi  

Microsoft Academic Search

We consider the problems of voice over wireless LANs and voice communications over heterogeneous asynchronous tandem networks, including digital cellular, VoIP, and voice over Wi-Fi. For voice over Wi-Fi, we minimize retransmissions by combining new packetization methods and packet loss concealment approaches. We demonstrate that tandem network connections can suffer significant loss in voice quality, even with ideal channels. We

Jerry D. Gibson; Bo Wei



Quantitative Caffeine Analysis Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System  

Microsoft Academic Search

Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography\\/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment

Michael J Ford; Michael A. Deibel; Bruce A Tomkins; Gary J Van Berkel



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

NASA Astrophysics Data System (ADS)

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

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


Ligand binding by the tandem glycine riboswitch depends on aptamer dimerization but not double ligand occupancy.  


The glycine riboswitch predominantly exists as a tandem structure, with two adjacent, homologous ligand-binding domains (aptamers), followed by a single expression platform. The recent identification of a leader helix, the inclusion of which eliminates cooperativity between the aptamers, has reopened the debate over the purpose of the tandem structure of the glycine riboswitch. An equilibrium dialysis-based assay was combined with binding-site mutations to monitor glycine binding in each ligand-binding site independently to understand the role of each aptamer in glycine binding and riboswitch tertiary interactions. A series of mutations disrupting the dimer interface was used to probe how dimerization impacts ligand binding by the tandem glycine riboswitch. While the wild-type tandem riboswitch binds two glycine equivalents, one for each aptamer, both individual aptamers are capable of binding glycine when the other aptamer is unoccupied. Intriguingly, glycine binding by aptamer-1 is more sensitive to dimerization than glycine binding by aptamer-2 in the context of the tandem riboswitch. However, monomeric aptamer-2 shows dramatically weakened glycine-binding affinity. In addition, dimerization of the two aptamers in trans is dependent on glycine binding in at least one aptamer. We propose a revised model for tandem riboswitch function that is consistent with these results, wherein ligand binding in aptamer-1 is linked to aptamer dimerization and stabilizes the P1 stem of aptamer-2, which controls the expression platform. PMID:25246650

Ruff, Karen M; Strobel, Scott A



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


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

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



Tandem antioxidant enzymes confer synergistic protective responses in experimental filariasis.  


Helminth parasites use antioxidant defence strategies for survival during oxidative stress due to free radicals in the host. Accordingly, tissue-dwelling filarial parasites counteract host responses by releasing a number of antioxidants. Targeting these redox regulation proteins together, would facilitate effective parasite clearance. Here, we report the combined effect of protective immune responses trigged by recombinant Wuchereria bancrofti thioredoxin (WbTRX) and thioredoxin peroxidase (WbTPX) in an experimental filarial model. The expression of WbTRX and WbTPX in different stages of the parasite and their cross-reactivity were analysed by enzyme-linked immunosorbent assay (ELISA). The immunogenicity of recombinant proteins and their protective efficacy were studied in animal models when immunized in single or cocktail mode. The antigens showed cross-reactive epitopes and induced high humoral and cellular immune responses in mice. Further, parasite challenge against Brugia malayi L3 larvae in Mastomys coucha conferred significant protection of 57% and 62% against WbTRX and WbTPX respectively. The efficacy of L3 clearance was significantly higher (71%) (P <  0.001) when the antigens were immunized together, showing a synergistic effect in multiple-mode vaccination. Hence, the study suggests WbTRX and WbTPX to be attractive vaccine candidates when immunized together and provides a tandem block for parasite elimination in the control of lymphatic filariasis. PMID:23676147

Prince, P R; Madhumathi, J; Anugraha, G; Jeyaprita, P J; Reddy, M V R; Kaliraj, P



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.



Flow past two tandem square cylinders vibrating transversely in phase  

NASA Astrophysics Data System (ADS)

Numerical investigations have been carried out to study the wake characteristics of flow past two tandem square cylinders vibrating in phase. Both the cylinders vibrate in a transverse direction, i.e., perpendicular to the incoming flow with the same frequency and amplitude. The frequency of vibration of the cylinders and the inter-cylinder spacing are varied for fixed values of the Reynolds number (Re = 100) and the amplitude ratio (A/D = 0.4). The synchronous or lock-in regime for the oscillatory wake of the vibrating cylinders has been identified by varying the frequency of the vibration from {{f}_{e}} = 0.4 {{f}_{0}} to 1.6 {{f}_{0}} ({{f}_{0}} being the frequency of vortex shedding behind a stationary square cylinder). The characteristics of lift and drag and the mechanism of vortex shedding are studied by varying the excitation frequency within the lock-in range for each value of inter-cylinder spacing. The complex interaction of flow between the cylinders gives rise to a variety of characteristically different shedding patterns in their wake. For values of inter-cylinder spacing equal to 2D and 3D, periodic, as well as quasi-periodic, lock-in behaviors are observed in the synchronous range.

Mithun, M. G.; Tiwari, Shaligram



Learning Peptide-Spectrum Alignment Models for Tandem Mass Spectrometry  

PubMed Central

We present a peptide-spectrum alignment strategy that employs a dynamic Bayesian network (DBN) for the identification of spectra produced by tandem mass spectrometry (MS/MS). Our method is fundamentally generative in that it models peptide fragmentation in MS/MS as a physical process. The model traverses an observed MS/MS spectrum and a peptide-based theoretical spectrum to calculate the best alignment between the two spectra. Unlike all existing state-of-the-art methods for spectrum identification that we are aware of, our method can learn alignment probabilities given a dataset of high-quality peptide-spectrum pairs. The method, moreover, accounts for noise peaks and absent theoretical peaks in the observed spectrum. We demonstrate that our method outperforms, on a majority of datasets, several widely used, state-of-the-art database search tools for spectrum identification. Furthermore, the proposed approach provides an extensible framework for MS/MS analysis and provides useful information that is not produced by other methods, thanks to its generative structure.

Halloran, John T.; Bilmes, Jeff A.; Noble, William S.



Sequence analysis of styrenic copolymers by tandem mass spectrometry.  


Styrene and smaller molar amounts of either m-dimethylsilylstyrene (m-DMSS) or p-dimethylsilylstyrene (p-DMSS) were copolymerized under living anionic polymerization conditions, and the compositions, architectures, and sequences of the resulting copolymers were characterized by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem mass spectrometry (MS(2)). MS analysis revealed that linear copolymer chains containing phenyl-Si(CH3)2H pendants were the major product for both DMSS comonomers. In addition, two-armed architectures with phenyl-Si(CH3)2-benzyl branches were detected as minor products. The comonomer sequence in the linear chains was established by MS(2) experiments on lithiated oligomers, based on the DMSS content of fragments generated by backbone C-C bond scissions and with the help of reference MS(2) spectra obtained from a polystyrene homopolymer and polystyrene end-capped with a p-DMSS block. The MS(2) data provided conclusive evidence that copolymerization of styrene/DMSS mixtures leads to chains with a rather random distribution of the silylated comonomer when m-DMSS is used, but to chains with tapered block structures, with the silylated units near the initiator, when p-DMSS is used. Hence, MS(2) fragmentation patterns permit not only differentiation of the sequences generated in the synthesis, but also the determination of specific comonomer locations along the polymer chain. PMID:25181590

Yol, Aleer M; Janoski, Jonathan; Quirk, Roderic P; Wesdemiotis, Chrys



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. PMID:24634165

Sun, Bing; Kawahara, Masahiro; Nagamune, Teruyuki



Tandem Differential Mobility Analyzer/Aerodynamic Particle Sizer (APS) Handbook  

SciTech Connect

The tandem differential mobility analyzer (TDMA) is a single instrument that cycles through a series of complementary measurements of the physical properties of size-resolved submicron particles. In 2008, the TDMA was augmented through the addition of an aerodynamic particle sizer (APS), which extends the upper limit of the measured size distribution into the supermicron range. These two instruments are operated in parallel, but because they are controlled by a common computer and because the size distributions measured by the two are integrated in the produced datastreams, they are described together here. Throughout the day, the TDMA sequentially measures submicron aerosol size distributions and size-resolved hygroscopic growth distributions. More specifically, the instrument is operated as a scanning DMA to measure size distributions and as a TDMA to measure size-resolved hygroscopicity. A typical measurement sequence requires roughly 45 minutes. Each morning additional measurements are made of the relative humidity (RH) dependent hygroscopicity and temperature-dependent volatility of size-resolved particles. When the outside temperature and RH are within acceptable ranges, the hydration state of size-resolved particles is also characterized. The measured aerosol distributions complement the array of aerosol instruments in the Aerosol Observing System (AOS) and provide additional details of the light-scattering and cloud-nucleating characteristics of the aerosol.

Collins, D



Fast atom bombardment tandem mass spectrometry of carotenoids  

SciTech Connect

Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

van Breeman, R.B. [Univ. of Illinois, Chicago, IL (United States); Schmitz, H.H.; Schwartz, S.J. [North Carolina State Univ., Raleigh, NC (United States)



From evaporation to solution processed organic tandem solar cells  

E-print Network

In this study, we have investigated the possibility to realize different types of stacked, serially connected organic solar cells. First of all, we combined solution processed MDMO-PPV:PCBM or P3HT:PCBM and evaporated ZnPc-C60 bulkheterojunction solar cells to achieved tandem cells exploiting the complementary absorption spectra of each single cells. Such devices exhibit open circuit voltages of 1V with a short-circuit current of approximately 5mA/cm and a fill factor of 0.35 under simulated AM1.5 illumination. In the case of stacked, series connected cells with all active layers processed from solution, we observed a significant increase of the open circuit voltage in comparison with the single junction cells: Device fabricated from two bilayers comprising MDMO-PPV and PCBM as photoactive materials exhibit 1.28V open circuit voltage, 1.1mA/cm short circuit current and a fill factor of 0.45 under simulated AM1.5 illumination.

H. -j. Prall; R. Autengruber; M. Egginger; G. Dennler; N. S. Sariciftci


Hemodynamics in two tandem aneurysms treated with flow diverters.  


The purpose of this study was to investigate whether the occlusion time of cerebral aneurysms treated with flow diverters depends on the hemodynamic conditions created immediately after treatment. A case study of a pair of tandem intracranial aneurysms that were treated with flow-diverting devices and occluded at different times was carried out. A patient-specific computational fluid dynamics model was constructed from 3D rotational angiography images. Blood flow simulations were carried out under pulsatile physiologic conditions, and hemodynamic variables before and after deployment of the flow-diverting devices were quantified and compared. The flow-diverting devices reduced aneurysm inflow rates, intra-aneurysmal flow velocities, shear rates, and wall shear stresses. The flow patterns after flow modulation by the flow diverters were smoother and with less swirling. The reductions in hemodynamic quantities depended on the aneurysm and parent artery and were larger in the aneurysm that occluded faster. The results of this case study suggest that the larger the reduction in the hemodynamic variables considered, the shorter the time it takes for the aneurysm to thrombose. This result can help us better define the goal of these interventions. PMID:24353243

Mut, Fernando; Scrivano, Esteban; Bleise, Carlos; Lylyk, Pedro; Cebral, Juan



Probabilistic consensus scoring improves tandem mass spectrometry peptide identification.  


Database search is a standard technique for identifying peptides from their tandem mass spectra. To increase the number of correctly identified peptides, we suggest a probabilistic framework that allows the combination of scores from different search engines into a joint consensus score. Central to the approach is a novel method to estimate scores for peptides not found by an individual search engine. This approach allows the estimation of p-values for each candidate peptide and their combination across all search engines. The consensus approach works better than any single search engine across all different instrument types considered in this study. Improvements vary strongly from platform to platform and from search engine to search engine. Compared to the industry standard MASCOT, our approach can identify up to 60% more peptides. The software for consensus predictions is implemented in C++ as part of OpenMS, a software framework for mass spectrometry. The source code is available in the current development version of OpenMS and can easily be used as a command line application or via a graphical pipeline designer TOPPAS. PMID:21644507

Nahnsen, Sven; Bertsch, Andreas; Rahnenführer, Jörg; Nordheim, Alfred; Kohlbacher, Oliver



A tandem mirror hybrid plume plasma propulsion facility  

NASA Technical Reports Server (NTRS)

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.



Tandem mass spectrometry of multiply charged peptides and proteins  

SciTech Connect

In the past two years electrospray ionization (ESI), originally described by Dole and coworkers and reinvigorated by Fenn and coworkers, has received considerable attention as a soft ionization source for mass spectrometry. The ESI method produces intact, multiply charged, gas phase molecular ions of peptides and proteins from aqueous solution with mass to charge ratios (m/a) that are easily within the range of quadrupole mass spectrometers. Because of the possible additional structural information from collisionally induced dissociation (CID)/tandem mass spectrometry, multiply charged ions are likely candidates for examination by this technique, possibly producing all or significant portions of the amino acid sequence. Although the multiply charged ions give abundant fragmentation, it is still a question whether meaningful fragmentation can be efficiently produced by CID. It would also be anticipated that the charge state of the parent ion might significantly affect the daughter ion spectra both in ions observed and their intensities. Three peptides, mellitin, glucagon, and the synthetic T/sub 1/ trypstic fragment of glucagon, and the protein cytochrome-c, have been investigated to examine these issues. 5 refs., 1 fig.

Barinaga, C.J.; Udseth, H.R.; Smith, R.D.



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.



Rapid assessment of the coenzyme Q10 redox state using ultrahigh performance liquid chromatography tandem mass spectrometry.  


An improved method for accurate and rapid assessment of the coenzyme Q10 (CoQ10) redox state using ultrahigh performance liquid chromatography tandem mass spectrometry was described, with particular attention given to the instability of the reduced form of CoQ10 during sample preparation, chromatographic separation and mass spectrometric detection. As highly lipophilic compounds in complex biological matrices, both reduced and oxidized forms of CoQ10 were extracted simultaneously from the tissue samples by methanol which is superior to ethanol and isopropanol. After centrifugation, the supernatants were immediately separated on a C18 column with isocratic elution using methanol containing 2 mM ammonium acetate as a non-aqueous mobile phase, and detected by positive electrospray ionization tandem mass spectrometry in multiple reaction monitoring (MRM) mode. Ammonium acetate as an additive in methanol provided enhanced mass spectrometric responses for both forms of CoQ10, primarily due to stable formation of adduct ions [M + NH4](+), which served as precursor ions in positive ionization MRM transitions. The assay showed a linear range of 8.6-8585 ng mL(-1) for CoQ10H2 and 8.6-4292 ng mL(-1) for CoQ10. The limits of detection (LODs) were 7.0 and 1.0 ng mL(-1) and limits of quantification (LOQs) were 15.0 and 5.0 ng mL(-1) for CoQ10H2 and CoQ10, respectively. This rapid extractive and analytical method could avoid artificial auto-oxidation of the reduced form of CoQ10, enabling the native redox state assessment. This reliable method was also successfully applied for the measurement of the CoQ10 redox state in liver tissues of mice exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin, revealing the down-regulated mitochondrial electron transport chain. PMID:25140668

Tang, Zhi; Li, Shangfu; Guan, Xinyuan; Schmitt-Kopplin, Philippe; Lin, Shuhai; Cai, Zongwei



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

PubMed Central

Background Owing to frequent administration of a wide range of pharmaceutical products, various environmental waters have been found to be contaminated with pharmacologically active substances. For example, stanozolol, a synthetic anabolic steroid, is frequently misused for performance enhancement as well as for illegal growth promoting purposes in veterinary practice. Previously we reported stanozolol in hair samples collected from subjects living in Budapest. For this reason we initiated this study to explore possible environmental sources of steroid contamination. The aim of this study was to develop a method to monitor stanozolol in aqueous matrices using liquid chromatography tandem mass spectrometry (LC-MS/MS). Results Liquid-liquid extraction using pentane was found to be an efficient method for the extraction of stanozolol from water samples. This was followed by direct detection using LC-MS/MS. The method was capable of detecting 0.25 pg/mL stanozolol when only 5 mL water was processed in the presence of stanozolol D3 as internal standard. Fifteen bottled waters analysed were found to be negative for stanozolol. However, three out of six samples from the Danube river, collected from December '09 to November '10, were found to contain stanozolol at concentrations up to 1.82 pg/mL. In contrast, only one sample (out of six) of urban tap water from Budapest city was found to contain stanozolol, at a concentration of 1.19 pg/mL. Conclusion The method developed is efficient, rapid, reproducible, sensitive and robust for the detection of stanozolol in aqueous matrices. PMID:21999747



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. PMID:24521244



[Cloning, expression and screening tandem repeats of the Z domain of Staphylococcus aureus protein A].  


To screen an efficient recombinant Staphylococcus aureus protein A (SpA) for preparing matrix for affinity purification of immunoglobulin G (IgG), a genetic engineering approach was used to obtain monomer, two, three, four and five tandem repeats genes of the Z domain of SpA, then the genes were cloned into expression vector pET-22b and subsequently expressed in Escherichia coli BL21 (DE3). After induction with lactose, the target proteins were purified by Ni2+ affinity chromatography. The proteins with two, three, four and five tandem repeats of the Z domain were then coupled to CNBr-activated Sepharose 4B as an affinity chromatography matrix for affinity purification of human IgG. Furthermore, the differences in protein yield and IgG-binding capacity at different recombinant proteins were analyzed. The target proteins with monomer and tandem repeats of the Z domain had an effective expression in the genetic engineering bacteria. IgG could be specifically absorbed from human plasma by affinity chromatography. The protein yield and amount of IgG absorption of per mole protein could be improved by increasing the tandem repeats number of the Z domain. Compared with other tandem repeats, four tandem repeats of the Z domain exhibited more protein yield (160 mg/10 g wet cells) and higher level of IgG absorption (34.4 mg human IgG/mL gel). Therefore, four tandem repeats of the Z domain is more suitable for preparing matrix for affinity purification of IgG. PMID:23593874

Wan, Yi; Zi, Jing; Zhang, Kun; Zhang, Zhimin; Zhang, Yuejuan; Wang, Yan; Wang, Jun



Biocatalyst Enhancement  

EPA Science Inventory

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


Tandem Mass Spectrometry of Modified and Platinated Oligoribonucleotides  

NASA Astrophysics Data System (ADS)

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

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



Tandem mass spectrometry of modified and platinated oligoribonucleotides.  


Therapeutic approaches for treatment of various diseases aim at the interruption of transcription or translation. Modified oligonucleotides, such as 2'-O-methyl- and methylphosphonate-derivatives, exhibit high resistance against cellular nucleases, thus rendering application for, e.g., antigene or antisense purposes possible. Other approaches are based on administration of cross-linking agents, such as cis-diamminedichloroplatinum(II) (cisplatin, DDP), which is still the most widely used anticancer drug worldwide. Due to the formation of 1,2-intrastrand cross links at adjacent guanines, replication of the double-strand is disturbed, thus resulting in significant cytotoxicity. Evidence for the gas-phase dissociation mechanism of platinated RNA is given, based on nano-electrospray ionization high-resolution multistage tandem mass spectrometry (MS(n)). Confirmation was found by investigating the fragmentation pattern of platinated and unplatinated 2'-methoxy oligoribonucleotide hexamers and their corresponding methylphosphonate derivatives. Platinated 2'-methoxy oligoribonucleotides exhibit a similar gas-phase dissociation behavior as the corresponding DNA and RNA sequences, with the 3'-C-O bond adjacent to the vicinal guanines being cleaved preferentially, leading to w(x)-ion formation. By examination of the corresponding platinated methylphosphonate derivatives of the 2'-methoxy oligoribonucleotides, the key role of the negatively charged phosphate oxygen atoms in direct proximity to the guanines was proven. The significant alteration of fragmentation due to platination is demonstrated by comparison of the fragment ion patterns of unplatinated and platinated 2'-O-methyl- and 2'-O-methyl methylphosphonate oligoribonucleotides, and the results obtained by H/D exchange experiments. PMID:21472522

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



Flow around two tandem square cylinders near a plane wall  

NASA Astrophysics Data System (ADS)

An experimental study has been conducted to investigate the flow around two identical square cylinders in tandem arrangement and placed near a plane wall at a Reynolds number of 6,300. The inter-cylinder spacing ratio was varied from S * = 0.5 to 6, and the cylinder-to-wall gap ratio from G * = 0.25 to 2. Totally, 42 cases were considered to systematically examine the effects of wall proximity and the mutual interference between the two cylinders in the normalized gap-spacing ( G *- S *) plane. The flow fields were captured using digital particle image velocimetry, in conjunction with measurements of the fluid forces (drag and lift) acting on the downstream cylinder using a piezoelectric load cell. The results show that the flow is highly dependent on the combined values of G * and S *. Categories relating to G * could be broadly classified as small-gap regime ( G * < 0.5) at which periodic vortex shedding from the cylinders is suppressed, intermediate-gap regime (0.5 < G * < 1) where vortex shedding occurs but is under the influence of the wall proximity, and large-gap regime ( G * > 1) where the wall effects become negligible. Similarly, the flow interference between the two cylinders can be divided into three basic categories as a function of S *, namely, shielding regime at S * < 1, reattachment regime at 1 < S * < 3, and impinging regime at S * > 3. Variations of force coefficients, amplitude spectra, Strouhal numbers, and Reynolds shear stress with G * and S * are presented to characterize the different flow regimes.

Wang, X. K.; Hao, Z.; Zhang, J.-X.; Tan, S. K.



Characterization of linear and branched polyacrylates by tandem mass spectrometry.  


The unimolecular degradation of alkali-metal cationized polyacrylates with the repeat unit CH(2)CH(COOR) and a variety of ester pendants has been examined by tandem mass spectrometry. The fragmentation patterns resulting from collisionally activated dissociation depend sensitively on the size of the ester alkyl substituent (R). With small alkyl groups, as in poly(methyl acrylate), lithiated or sodiated oligomers (M) decompose via free-radical chemistry, initiated by random homolytic C-C bond cleavages along the polymer chain. The radical ions formed this way dissociate further by backbiting rearrangements and beta scissions to yield a distribution of terminal fragments with one of the original end groups and internal fragments with 2-3 repeat units. If the ester alkyl group bears three or more carbon atoms, cleavages within the ester moieties become the predominant decomposition channel. This distinct reactivity is observed if R = t-butyl, n-butyl, or the mesogenic group (CH(2))(11)-O-C(6)H(4)-C(6)H(4)-CN. The [M+alkali metal](+) ions of the latter polyacrylates dissociate largely by charge-remote 1,5-H rearrangements that convert COOR to COOH groups by expulsion of 1-alkenes. The acid groups may displace an alcohol unit from a neighboring ester pendant to form a cyclic anhydride, unless hindered by steric effects. Using atom transfer radical polymerization, hyperbranched polyacrylates were prepared carrying ester groups both within and between the branches. Unique alkenes and alcohols are cleaved from ester groups at the branching points, enabling determination of the branching architecture. PMID:18373231

Chaicharoen, Kittisak; Polce, Michael J; Singh, Anirudha; Pugh, Coleen; Wesdemiotis, Chrys



Sharpening the Tandem Walking Test for Screening Peripheral Neuropathy  

PubMed Central

Objective Few tests of functional motor behavior are useful for rapidly screening people for lower extremity peripheral neuropathy. The goal of this study was to improve the widely used Tandem Walking test (TW). Methods We tested adult normals and ambulatory peripheral neuropathy patients (PN) with eyes open and eyes closed, while they performed TW on industrial carpeting, in sock-covered feet. Each subject wore a torso-mounted inertial motion unit to measure kinematic data. PN subjects’ data were also compared to historical data on patients with vestibular impairments (VI). Results The normal and PN groups differed significantly on TW on the number of steps completed. PN and VI data also differed significantly on both visual conditions. Kinematic data showed that PN patients were more unstable than normals. For the number of steps taken during the eyes open condition receiver operating characteristic (ROC) values were only 0.81. For the number of steps taken during the eyes closed condition, however, ROC=0.88. Although not optimal, this ROC value is better. Sensitivity and specificity at a cut-off of 2 steps were 0.81 and 0.92, respectively, and at a cut-off of 3 steps was 0.86 and 0.75, respectively. ROC values for kinematic data were all < 0.8 and, when combined with the ROC value for the number of steps, the total ROC value did not improve appreciably. Conclusions Although not ideal for screening patients who may have peripheral neuropathy, counting the number of steps during TW is a quick and useful clinical test. TW is most sensitive to peripheral neuropathy patients when they are tested with eyes closed. PMID:24096950

Cohen, Helen S.; Mulavara, Ajitkumar P.; Peters, Brian T.; Sangi-Haghpeykar, Haleh; Kung, Doris H.; Mosier, Dennis R.; Bloomberg, Jacob J.



Tandem solar cells deposited using hot-wire chemical vapor deposition  

NASA Astrophysics Data System (ADS)

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

van Veen, M. K.



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. PMID:22536906



Rapidly convergent algorithms for 3-D tandem and stellarator equilibria in the paraxial approximation  

SciTech Connect

Tandem and stellarator equilibria at high ..beta.. have proved hard to compute and the relaxation methods of Bauer et al., Chodura and Schluter, Hirshman, Strauss, and Pearlstein et al. have been slow to converge. This paper reports an extension of the low-..beta.. analytic method of Pearlstein, Kaiser, and Newcomb to arbitrary ..beta.. for tandem mirrors which converges in 10 to 20 iterations. Extensions of the method to stellarator equilibria are proposed and are very close to the analytic method of Johnson and Greene - the stellarator expansion. Most of the results of all these calculations can be adequately described by low-..beta.. approximations since the MHD stability limits occur at low ..beta... The tandem mirror, having weak curvature and a long central cell, allows finite Larmor radius effects to eliminate most ballooning modes and offers the possibility of really high average ..beta... This is the interest in developing such three-dimensional numerical algorithms.

McNamara, B.



Pt-free tandem molecular photoelectrochemical cells for water splitting driven by visible light.  


Photoelectrochemical (PEC) cells using molecular catalysts to split water into hydrogen and oxygen have been investigated intensively during the past years. However, the high-cost of Pt counter electrodes and instability of molecular PEC cells hinder the practical applications. We describe in this article a Pt-free tandem molecular PEC cell, for the first time, employing molecular ruthenium- and cobalt-catalysts with strong dipicolinic acid anchoring groups on the respective photoanode and photocathode for total water splitting. The Pt-free tandem molecular PEC cell showed an effective and steady photocurrent density of ca. 25 ?A cm(-2) for water splitting driven by visible light without external bias. This study indicates that tandem molecular PEC cells can provide great potential to the Pt-free devices for light driven total water splitting. PMID:25341620

Fan, Ke; Li, Fusheng; Wang, Lei; Daniel, Quentin; Gabrielsson, Erik; Sun, Licheng



Architecture, performance, and implementation of the tandem banyan fast packet switch  

NASA Technical Reports Server (NTRS)

The authors propose a space-division fast packet switch architecture based on banyan interconnection networks, called the tandem banyan switching fabric. It consists of placing banyan networks in tandem, offering multiple paths from each input to each output, thus overcoming in a very simple way the effect of conflicts among packets (to which banyan networks are prone) and achieving output buffering. From a hardware implementation perspective, this architecture is simple in that it consists of several instances of only two VLSI chips, one implementing the banyan network and the other implementing the output buffer function. The basic structure and operation of the tandem banyan switching fabric are described, and its performance is discussed. The authors propose a modification to the basic structure which decreases the hardware complexity of the switch while maintaining its performance. An implementation of the banyan network using a high-performance BiCMOS sea-of-gates on 0.8-micron technology is reported.

Tobagi, Fouad A.; Chiussi, Fabio M.; Kwok, Timothy



Tandem-disk theory - With particular reference to vertical axis wind turbines  

NASA Astrophysics Data System (ADS)

The effect of blade shape on the performance of straight-blade turbines is investigated, and an attempt is made to establish the tandem disk system as a model for vertical axis wind turbines. Two unknowns are chosen as independent parameters, and expressions for the windspeeds and power coefficients are obtained in terms of these parameters. Pressure is varied between the two disks, and the power coefficient for the tandem disk model is evaluated. The range of validity of the momentum theory is determined, although with some difficulty, for the single-disk and tandem models. Finally, the theory can be alternatively combined with the blade-element theory, which yields two additional equations, thus resolving the indeterminacy.

Healey, J. V.



Tandem sequence of cross metathesis--ring-closing metathesis reaction of alkynyl silyloxy-tethered enynes.  


A tandem cross metathesis (CM)--ring-closing metathesis (RCM) sequence to form cyclic siloxanes is reported. This new enyne metathesis platform expands the scope and utility of the regio- and stereoselective cross metathesis reaction between silylated alkynes and terminal alkenes. The initial cross metathesis was directed to occur on the alkyne by employing sterically hindered mono-, di-, and trisubstituted alkenes tethered to the alkyne via silyl ether. The regio- and stereoselectivity feature of the initial CM step in this tandem CM-RCM process is identical to that of the CM reactions of silylated alkynes and alkenes. This tandem sequence provides both synthetically useful silylated 1,3-diene building blocks and insights into the reaction mechanism of the enyne metathesis reaction. PMID:15984868

Park, Sangho; Kim, Mansuk; Lee, Daesung



Tandem repeats and heteroplasmy in the mitochondrial DNA control region of the loggerhead shrike (Lanius ludovicianus).  


We report the presence of a 128 bp tandem repeat in the mitochondrial control region of the loggerhead shrike (Aves: Lanius ludovicianus). All individuals examined had either two or three copies of the repeat or were heteroplasmic for two and three copies. This is the first direct demonstration of a tandem repeat associated with heteroplasmy in the control region of a bird. A novel model for repeat duplication, which involves an inverted repeat located adjacent to the tandemly repeated sequence, is presented. Individuals with three repeats are absent from the endangered population of San Clemente loggerhead shrike in southern California, suggesting that the island endemic has a small effective population size and that there is insignificant gene flow from the adjacent mainland. PMID:8742819

Mundy, N I; Winchell, C S; Woodruff, D S



Hybrid inorganic-organic tandem solar cells for broad absorption of the solar spectrum.  


We report the first hybrid tandem solar cell with solution processable active layers using colloidal PbS quantum dots (QDs) as the front subcell in combination with a polymer-fullerene rear subcell. Al/WO3 is introduced as an interlayer, yielding an open circuit voltage (VOC) equal to about 92% of the sum of the VOC of the subcells. The device exhibits a power conversion efficiency of 1.8%. Optical simulations of various tandem configurations show that combining PbS QDs with small-bandgap polymers is a promising strategy to obtain tandem solar cells with a very broad absorption range and a high short circuit current. PMID:24652186

Speirs, M J; Groeneveld, B G H M; Protesescu, L; Piliego, C; Kovalenko, M V; Loi, M A



Pulsating Tandem Microbubble for Localized and Directional Single Cell Membrane Poration  

PubMed Central

The interaction of laser-generated tandem microbubble (maximum diameter about 50 ?m) with single (rat mammary carcinoma) cells is investigated in a 25-?m liquid layer. Anti-phase and coupled oscillation of the tandem microbubble leads to the formation of alternating, directional microjets (with max. microstreaming velocity of 10 m/s) and vortices (max. vorticity of 350,000 s?1) in opposite directions. Localized and directional membrane poration (200 nm to 2 ?m in pore size) can be produced by the tandem microbubble in an orientation and proximity dependent manner, which is absence from a single oscillating microbubble of comparable size and at the same stand-off distance. PMID:20868077

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



Aeroacoustic Simulations of Tandem Cylinders with Subcritical Spacing  

NASA Technical Reports Server (NTRS)

Tandem cylinders are being studied because they model a variety of component level interactions of landing gear. The present effort is directed at the case of two identical cylinders with their centroids separated in the streamwise direction by 1.435 diameters. Experiments in the Basic Aerodynamic Research Tunnel and Quiet Flow Facility at NASA Langley Research Center have provided an extensive experimental database of the nearfield flow and radiated noise. The measurements were conducted at a Mach number of 0.1285 and Reynolds number of 1.66x10(exp 5) based on the cylinder diameter. A trip was used on the upstream cylinder to insure a fully turbulent flow separation and, hence, to simulate a major aspect of high Reynolds number flow. The parallel computational effort uses the three-dimensional Navier-Stokes solver CFL3D with a hybrid, zonal turbulence model that turns off the turbulence production term everywhere except in a narrow ring surrounding solid surfaces. The experiments exhibited an asymmetry in the surface pressure that was persistent despite attempts to eliminate it through small changes in the configuration. To model the asymmetry, the simulations were run with the cylinder configuration at a nonzero but small angle of attack. The computed results and experiments are in general agreement that vortex shedding for the spacing studied herein is weak relative to that observed at supercritical spacings. Although the shedding was subdued in the simulations, it was still more prominent than in the experiments. Overall, the simulation comparisons with measured near-field data and the radiated acoustics are reasonable, especially if one is concerned with capturing the trends relative to larger cylinder spacings. However, the flow details of the 1.435 diameter spacing have not been captured in full even though very fine grid computations have been performed. Some of the discrepancy may be associated with the simulation s inexact representation of the experimental configuration, but numerical and flow modeling errors are also likely contributors to the observed differences.

Lockard, David P.; Choudhari, Meelan M.; Khorrami, Mehdi R.; Neuhart, Dan H.; Hutcheson, Florence V.; Brooks, Thomas F.; Stead, Daniel J.



US forensic Y-chromosome short tandem repeats database.  


A forensic Y-STR database generated in the US was compiled with profiles containing a portion or complete typing of 16 STR markers DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS456, DYS458, DYS635, DYS448, and Y GATA H4. There were 17,447 samples in the version of database in which 77% and 20% were collected in North America and Asia, respectively. The database was separated into six general populations, African American, Asian, Caucasian, Hispanic, Indian, and Native American. Each population was further classified into subgroups according to geographic regions. Some subgroups were tested, found to be homogenous and merged together. Allele and haplotype frequencies, as well as sample sizes were summarized. Of the full haplotypes (i.e., 16 STRs without missing data), 93.7% in total population were distinct, 92.9% were population specific, and 89.3% were only observed once. The majority of shared haplotypes were found among North American populations as a result of admixture lasting the past few hundred years. The power of discrimination (PD), coancestry coefficient (F(st)), and coefficient of gene differentiation (G(st)) at locus and haplotype levels were also calculated. The most polymorphic marker was DYS385; this marker contains a tandem duplication and actually is composed of two loci. Both G(st) and F(st) estimates were very small with haplotypes composed of a high number of STRs haplotypes (e.g., 10-16 markers), although G(st) is slightly more conservative for these extended haplotypes. With Native American removed from the total population data set, the G(st) and F(st) estimates reduce further. PD was 0.9998 for the total population dataset for all 16 Y-STR markers. Three measures of Y-STR profile frequency were calculated: (1) unconditional haplotype frequency, (2) population substructure adjusted frequency, and (3) binomial upper bound of the haplotype frequency. The binomial upper bound is the most conservative estimate for most forensic applications. Estimates of the weight of a Y-STR haplotype can be estimated using population specific or total population databases. PMID:20817529

Ge, Jianye; Budowle, Bruce; Planz, John V; Eisenberg, Arthur J; Ballantyne, Jack; Chakraborty, Ranajit



Tandem repeat markers as novel diagnostic tools for high resolution fingerprinting of Wolbachia  

PubMed Central

Background Strains of the endosymbiotic bacterium Wolbachia pipientis are extremely diverse both genotypically and in terms of their induced phenotypes in invertebrate hosts. Despite extensive molecular characterisation of Wolbachia diversity, little is known about the actual genomic diversity within or between closely related strains that group tightly on the basis of existing gene marker systems, including Multiple Locus Sequence Typing (MLST). There is an urgent need for higher resolution fingerprinting markers of Wolbachia for studies of population genetics, horizontal transmission and experimental evolution. Results The genome of the wMel Wolbachia strain that infects Drosophila melanogaster contains inter- and intragenic tandem repeats that may evolve through expansion or contraction. We identified hypervariable regions in wMel, including intergenic Variable Number Tandem Repeats (VNTRs), and genes encoding ankyrin (ANK) repeat domains. We amplified these markers from 14 related Wolbachia strains belonging to supergroup A and were successful in differentiating size polymorphic alleles. Because of their tandemly repeated structure and length polymorphism, the markers can be used in a PCR-diagnostic multilocus typing approach, analogous to the Multiple Locus VNTR Analysis (MLVA) established for many other bacteria and organisms. The isolated markers are highly specific for supergroup A and not informative for other supergroups. However, in silico analysis of completed genomes from other supergroups revealed the presence of tandem repeats that are variable and could therefore be useful for typing target strains. Conclusions Wolbachia genomes contain inter- and intragenic tandem repeats that evolve through expansion or contraction. A selection of polymorphic tandem repeats is a novel and useful PCR diagnostic extension to the existing MLST typing system of Wolbachia, as it allows rapid and inexpensive high-throughput fingerprinting of closely related strains for which polymorphic markers were previously lacking. PMID:22375862



Identification of the major selenium compound, Se-Methionine, in three yeast (Saccharomyces cerevisiae) dietary supplements by on-line narrowbore liquid chromatography-electrospray tandem mass spectrometry.  


On-line monitoring of six Se-compounds was accomplished by using an XTerra MS C18 column coupled to electrospray tandem mass spectrometry (ES-MS-MS). In view of the nature of the compounds, the positively charged ion pairing agent tetraethylammoniumchloride (TEACl) was added to the mobile phase. The HPLC-ES-MS-MS method was optimized with six commercially available Se-compounds. Substitution of the analytical column by the narrowbore type significantly enhanced the sensitivity of the method. We were able to detect the m/z of these six molecules on-line. Furthermore, all product ions could be monitored. The method was applied to three different yeast-based supplements. They were submitted to proteolytic digestion and screened for their Se-content by HPLC-HG-AFS (hydride generation-atomic fluorescence spectrometry). By application of on-line narrowbore HPLC-electrospray tandem mass spectrometry, the main compound present in these three supplements, Se-Methionine, could be measured on its m/z and its product ions. The method can be further extended for on-line measurement of different Se-species in complex matrices PMID:15865193

Dumont, Emmie; De Cremer, Koen; Van Hulle, Marijn; Chéry, Cyrille C; Vanhaecke, Frank; Cornelis, Rita



Microfluidic chip based nano liquid chromatography coupled to tandem mass spectrometry for the determination of abused drugs and metabolites in human hair.  


A microfluidic chip based nano-HPLC coupled to tandem mass spectrometry (nano-HPLC-Chip-MS/MS) has been developed for simultaneous measurement of abused drugs and metabolites: cocaine, benzoylecgonine, cocaethylene, norcocaine, morphine, codeine, 6-acetylmorphine, phencyclidine, amphetamine, methamphetamine, MDMA, MDA, MDEA, and methadone in the hair of drug abusers. The microfluidic chip was fabricated by laminating polyimide films and it integrated an enrichment column, an analytical column and a nanospray tip. Drugs were extracted from hairs by sonication, and the chromatographic separation was achieved in 15 min. The drug identification and quantification criteria were fulfilled by the triple quardropule tandem mass spectrometry. The linear regression analysis was calibrated by deuterated internal standards with all of the R(2) at least over 0.993. The limit of detection (LOD) and the limit of quantification (LOQ) were from 0.1 to 0.75 and 0.2 to 1.25 pg/mg, respectively. The validation parameters including selectivity, accuracy, precision, stability, and matrix effect were also evaluated here. In conclusion, the developed sample preparation method coupled with the nano-HPLC-Chip-MS/MS method was able to reveal the presence of drugs in hairs from the drug abusers, with the enhanced sensitivity, compared with the conventional HPLC-MS/MS. PMID:22281681

Zhu, Kevin Y; Leung, K Wing; Ting, Annie K L; Wong, Zack C F; Ng, Winki Y Y; Choi, Roy C Y; Dong, Tina T X; Wang, Tiejie; Lau, David T W; Tsim, Karl W K



Identification of flavonoid glycosides in Rosa chinensis flowers by liquid chromatography-tandem mass spectrometry in combination with ¹³C nuclear magnetic resonance.  


Flowers of Rosa chinensis are widely used in traditional Chinese medicine as well as in food industry. Flavonoid glycosides are believed to be the major components in R. chinensis that are responsible for its antioxidant activities. In this work, a liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for analysis of flavonoid glycosides presented in ethyl acetate extract of dried R. chinensis flowers. Twelve flavonoid glycosides were separated and detected. By comparing the retention times, UV spectra, and tandem MS fragments with those of respective authentic compounds, eight flavonoid glycosides were unequivocally identified. Although the other four were also identified as flavonoid glycosides, the glycosylation positions could not be determined due to lack of authentic compounds. Fortunately, the glycosylation effects were clearly observed in the (13)C NMR spectrum of the extract. The detailed structural information was, therefore, obtained to identify the four flavonoid glycosides as quercetin-3-O-D-glucoside, quercetin-3-O-D-xyloside, kaempferol-3-O-D-xyloside and quercetin-3-O-D-(6?-coumaroyl)-galactoside. These flavonoid glycosides were detected and identified for the first time in this botanic material. This work reports on the first use of (13)C NMR of a mixture to enhance a rapid HPLC-MS/MS analysis. The proposed analytical protocol was validated with a mixture of authentic flavonoid glycosides. PMID:22749452

Qing, Lin-Sen; Xue, Ying; Zhang, Jian-Guang; Zhang, Zhi-Feng; Liang, Jian; Jiang, Yan; Liu, Yi-Ming; Liao, Xun



Mouse-Specific Tandem IgY7-SuperMix Immunoaffinity Separations for Improved LC-MS/MS Coverage of the Plasma Proteome  

SciTech Connect

We report on a customized mouse specific SuperMix immunoaffinity column and strategy for separating low abundance proteins from high and moderate abundance proteins in mouse plasma. When applied in tandem with a mouse IgY7 column that removes the seven most abundant proteins in blood, the SuperMix column captures >100 additional moderate abundance proteins, thus allowing significant enrichment of low abundance proteins in the flow-through fraction. A side-by-side comparison of results obtained from 2D-LC-MS/MS analyses of flow-through samples from IgY7 and SuperMix columns revealed a nearly two-fold improvement in the overall proteome coverage. Detection of low abundance proteins was also enhanced, as evidenced by a more than two-fold increase in the coverage of cytokines, growth factors, and other low abundance proteins. Moreover, the tandem separations are automated, reproducible, and allow effective identification of protein abundance differences from LC-MS/MS analyses. Considering the overall reproducibility and increased sensitivity using the IgY7-SuperMix separation system, we anticipate broad applications of this strategy for biomarker discovery using mouse models.

Zhou, Jianying; Petritis, Brianne O.; Petritis, Konstantinos; Norbeck, Angela D.; Weitz, Karl K.; Moore, Ronald J.; Camp, David G.; Kulkarni, Rohit N.; Smith, Richard D.; Qian, Weijun



Overview of the Applications of Tandem Mass Spectrometry (MS\\/MS) in Food Analysis of Nutritionally Harmful Compounds  

Microsoft Academic Search

Tandem mass spectrometry (MS\\/MS) has proved to be a useful and a time saving analytical tool, with many applications of direct detection of target molecules in food samples. When coupled with chromatographic techniques, it combines the separation capabilities of chromatography and the power of MS\\/MS as an identification and confirmation method. This article reviews the use of tandem mass spectrometry

Stamatia I. Kotretsou; Aglaia Koutsodimou




E-print Network

14TH EUROPEAN TURBULENCE CONFERENCE, 1-4 SEPTEMBER 2013, LYON, FRANCE TANDEM AIRFOIL VORTEX regime which may occur in tandem airfoil configurations at high angle of attack. It results from a detached flow on the downstream airfoil and a drop of the lift, rendering the elevators ineffective

Boyer, Edmond


Amplification of a tandem direct repeat within inverted repeats of Marek's disease virus DNA during serial in vitro passage.  

PubMed Central

DNA of the oncogenic strain BC-1 of Marek's disease virus contains three units of tandem direct repeats with 132 base pairs in the terminal repeat and internal repeat, respectively, of the long region of the Marek's disease virus genome, whereas the attenuated, nononcogenic viral DNA contains multiple units of the tandem direct repeats. Images PMID:3009876

Maotani, K; Kanamori, A; Ikuta, K; Ueda, S; Kato, S; Hirai, K



Tandem Repeat Deletion in the Alpha C Protein of Group B Streptococcus Is recA Independent  

Microsoft Academic Search

Group B streptococci (GBS) contain a family of protective surface proteins characterized by variable numbers of repeating units within the proteins. The prototype alpha C protein of GBS from the type Ia\\/C strain A909 contains a series of nine identical 246-bp tandem repeat units. We have previously shown that deletions in the tandem repeat region of the alpha C protein




Use of an ECR ion source in the high voltage terminal of the tandem accelerator at JAERI  

Microsoft Academic Search

Modern electron cyclotron resonance ion source (ECRIS)s are able to produce intense beams of highly charge positive ions, of which charge states are higher than those obtained from electron stripping at the high voltage terminal of tandem accelerators. It is possible to increase beam intensity, beam energy and beam species by utilizing an ECRIS in a tandem accelerator. A small

M. Matsuda; C. Kobayashi; S. Takeuchi



Design and Growth of III-V on Si Microwire Array Tandem Solar Cells Christopher T. Chen1  

E-print Network

Design and Growth of III-V on Si Microwire Array Tandem Solar Cells Christopher T. Chen1 , Daniel B Abstract -- Tandem Ga1-xInxP/Si microwire array solar cells are a route towards a high efficiency, low cost, flexible, wafer- free solar technology. Coupled full-field optical and device physics simulations of a Ga0

Atwater, Harry


Amorphous silicon based tandem solar cells entirely fabricated by hot-wire CVD  

Microsoft Academic Search

For the first time, we report on a-Si:H\\/a-Si:H tandem solar cells, entirely fabricated by hot-wire CVD. Until now, our effort to develop a-Si:H\\/a-Si:H tandem cells has resulted in a 7.0% initial efficiency. Two types of tunnel junction, n+-?c-Si:H\\/p+-a-SiC:H and n+-?c-Si:H\\/p+-?cSi:H, have been developed which yield low series resistance (<25 ?cm2). Systematic variation of top i-layer thickness was carried out to

U. Weber; A. R. Middya; C. Mukherjee; B. Schroeder



Very high frequency plasma deposited amorphous/nanocrystalline silicon tandem solar cells on flexible substrates  

NASA Astrophysics Data System (ADS)

The work in this thesis is to develop high quality intrinsic layers (especially nc-Si:H) for micromorph silicon tandem solar cells/modules on plastic substrates following the substrate transfer method or knows as the Helianthos procedure. Two objectives are covered in this thesis: (1) preliminary work on trial and optimization of single junction and tandem cells on glass substrate, (2) silicon film depositions on Al foil, and afterwards the characterization and development of these cells/modules on a plastic substrate. The first objective includes the development of suitable ZnO:Al TCO for nc Si:H single junction solar cells, fabrication of the aimed micromorph tandem solar cells on glass, and finally the optimization of the nc-Si:H i-layer for the depositions afterwards on Al foil. Chapter 3 addresses the improvement of texture etching of ZnO:Al by studying the HCl etching effect on ZnO:Al films sputter-deposited in a set substrate heater temperature series. With the texture-etched ZnO:Al front TCO, a single junction nc-Si:H solar cell was deposited with an initial efficiency of 8.33%. Chapter 4 starts with studying the light soaking and annealing effects on micromorph tandem solar cell. In the end, a highly stabilized bottom cell current limited tandem cell was made. The tandem shows an initial efficiency of 10.2%, and degraded only 6.9% after 1600 h of light soaking. In Chapter 5, the nc-Si:H i-layers were studied in 3 pressure and inter-electrode distance series. The correlations between plasma physics and the consequent i-layers’ properties are investigated. We show that the Raman crystalline ratio and porosity of the nc-Si:H layer have an interesting relation with the p•d product. By varying p and d, device quality nc-Si:H layer can be deposited at a high rate of 0.6 nm/s. These results in fact are a very important step for the second objective. The second objective is covered by the entire Chapter 6. All silicon layers are deposited on special aluminum foils. Completed devices (including single junction a Si:H, nc-Si:H and micromorph silicon tandem cells/modules) on plastic substrates are characterized and discussed. In the end, 2.5 cm2 area micromorph tandem cells on foil were fabricated with an initial efficiency of the best cell to be 8.12% (FF = 0.64). After 1000 h of light soaking, its efficiency and FF degraded about 15% and 14.2% respectively.

Liu, Y.



ECR (Electron Cyclotron Resonance) source for the HHIRF (Holifield Heavy Ion Research Facility) tandem accelerator  

SciTech Connect

Electron Cyclotron Resonance, ECR, ion source technology has developed rapidly since the original pioneering work of R. Geller and his group at Grenoble in the early 1970s. These ion sources are capable of producing intense beams of highly charged positive ions and are used extensively for cyclotron injection, linac injection, and atomic physics research. In this paper, the advantages of using an ECR heavy-ion source in the terminal of the Holifield Heavy Ion Research Facility (HHIRF) 25-MV tandem accelerator is discussed. A possible ECR system for installation in the HHIRF tandem terminal is described.

Olsen, D.K.; Alton, G.D.; Dowling, D.T.; Haynes, D.L.; Jones, C.M.; Juras, R.C.; Lane, S.N.; Meigs, M.J.; Mills, G.D.; Mosko, S.W.; Tatum, B.A.



Child abuse in medical setting presenting as gross hematuria: diagnosis by DNA short tandem repeats.  


Two sisters, aged 15 and 13 years, had previous epithelioid angiomyolipoma of the kidney and suspected thin basement membrane disease, respectively. They presented with 2 years of gross hematuria and new-onset heavy proteinuria. Extensive investigations failed to find an overt cause of their urinary manifestations. The diagnosis of child abuse in a medical setting was confirmed by DNA short tandem repeats analysis, which are the first documented cases in which factitious hematuria was thus diagnosed. Complex forms of child abuse in a medical setting may require forensic tests such as DNA short tandem repeats analysis for diagnosis. PMID:22732177

Tsai, Hsin-Lin; Yang, Ling-Yu; Chin, Tai-Wai; Chen, Po-Hon; Yen, Hsiu-Ju; Liu, Chin-Su; Wang, Hsin-Hui; Chang, Jei-Wen



Identification and Characterization of Cell-Specific Enhancer Elements for the Mouse ETF\\/Tead2 Gene  

Microsoft Academic Search

We have identified and characterized by transient transfection assays the cell-specific 117-bp enhancer sequence in the first intron of the mouse ETF (Embryonic TEA domain-containing factor)\\/Tead2 gene required for transcriptional activation in ETF\\/Tead2 gene-expressing cells, such as P19 cells. The 117-bp enhancer contains one GC-rich sequence (5?-GGGGCGGGG-3?), termed the GC box, and two tandemly repeated GA-rich sequences (5?-GGGGGAGGGG-3?), termed the

Yasuyuki Tanoue; Michio Yasunami; Kazuo Suzuki; Hiroaki Ohkubo



Tandem repeats discovery service (TReaDS) applied to finding novel cis-acting factors in repeat expansion diseases  

PubMed Central

Background Tandem repeats are multiple duplications of substrings in the DNA that occur contiguously, or at a short distance, and may involve some mutations (such as substitutions, insertions, and deletions). Tandem repeats have been extensively studied also for their association with the class of repeat expansion diseases (mostly affecting the nervous system). Comparative studies on the output of different tools for finding tandem repeats highlighted significant differences among the sets of detected tandem repeats, while many authors pointed up how critical it is the right choice of parameters. Results In this paper we present TReaDS - Tandem Repeats Discovery Service, a tandem repeat meta search engine. TReaDS forwards user requests to several state of the art tools for finding tandem repeats and merges their outcome into a single report, providing a global, synthetic, and comparative view of the results. In particular, TReaDS allows the user to (i) simultaneously run different algorithms on the same data set, (ii) choose for each algorithm a different setting of parameters, and (iii) obtain a report that can be downloaded for further, off-line, investigations. We used TReaDS to investigate sequences associated with repeat expansion diseases. Conclusions By using the tool TReaDS we discover that, for 27 repeat expansion diseases out of a currently known set of 29, long fuzzy tandem repeats are covering the expansion loci. Tests with control sets confirm the specificity of this association. This finding suggests that long fuzzy tandem repeats can be a new class of cis-acting elements involved in the mechanisms leading to the expansion instability. We strongly believe that biologists can be interested in a tool that, not only gives them the possibility of using multiple search algorithm at the same time, with the same effort exerted in using just one of the systems, but also simplifies the burden of comparing and merging the results, thus expanding our capabilities in detecting important phenomena related to tandem repeats. PMID:22536970



Stir bar sorptive extraction coupled to liquid chromatography-tandem mass spectrometry for the2 determination of pesticides in water samples: method validation and measurement uncertainty3  

E-print Network

1 Title :1 Stir bar sorptive extraction coupled to liquid chromatography-tandem mass spectrometry sorptive extraction followed by liquid desorption and high performance liquid12 chromatography with tandem chromatography-tandem mass spectrometry (LC-30 MSMS), pesticides, surface water, validation, measurement

Paris-Sud XI, Université de


Dextroamphetamine Enhances \\  

Microsoft Academic Search

Previous studies in animals and humans suggest that mono- amines enhance behavior-evoked neural activity relative to nonspecific background activity (i.e., increase signal-to-noise ratio). We studied the effects of dextroamphetamine, an indirect monoaminergic agonist, on cognitively evoked neural activity in eight healthy subjects using positron-emission tomography and the O15 water intravenous bolus method to measure re- gional cerebral blood flow (rCBF).

Venkata S. Mattay; Karen Faith Berman; Jill L. Ostrem; Giuseppe Esposito; John D. Van Horn; Llewellyn B. Bigelow; Daniel R. Weinberger



Investigation of matrix effects in bioanalytical high-performance liquid chromatography/tandem mass spectrometric assays: application to drug discovery.  


A series of studies was performed to investigate some of the causes for matrix effects ('ion suppression' or 'ion enhancement') in bioanalytical high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) assays. Previous studies have reported that matrix effects are mainly due to endogenous components in biological fluids and are a greater concern for electrospray ionization (ESI) than for atmospheric pressure chemical ionization (APCI). In this report we demonstrate that: (1) matrix effects can also be caused by exogenous materials, such as polymers contained in different brands of plastic tubes, or Li-heparin, a commonly used anticoagulant; (2) matrix effects are not only ionization mode (APCI or ESI) dependent, but also source design (Sciex, Finnigan, Micromass) dependent; and (3) for at least one vendor's design, we found the APCI mode to be more sensitive to matrix effects than the ESI mode. Based on these findings, we have proposed the following simple strategies to avoid matrix effects: (1) select the same brand of plastic tubes for processing and storing plasma samples and spiked plasma standards; (2) avoid using Li-heparin as the anticoagulant; and (3) try switching the ionization mode or switching to different mass spectrometers when matrix effects are encountered. These three strategies have allowed us to use protein precipitation and generic fast LC techniques to generate reliable LC/MS/MS data for the support of pharmacokinetic studies at the early drug discovery stage. PMID:12478560

Mei, Hong; Hsieh, Yunsheng; Nardo, Cymbylene; Xu, Xiaoying; Wang, Shiyong; Ng, Kwokei; Korfmacher, Walter A



Detection of peginesatide in equine serum using liquid chromatography-tandem mass spectrometry for doping control purposes.  


Erythropoietin (EPO) and its recombinant analogues are suspected to be illicitly administered to horses for performance enhancing purposes and, consequently, prohibited in equine sports. Recently, a new erythropoiesis-stimulating agent, peginesatide (Omontys, formerly referred to as Hematide), belonging to the upcoming class of EPO-mimetic peptides, received approval for the treatment of anaemia in humans with chronic kidney disease on dialysis. As the pegylated dimeric peptide of approximately 45 kDa without sequence homology to EPO is not detectable by conventional EPO detection assays, specific methods are bound to be established for horse sports drug testing. Thus, by fortifying equine serum with peginesatide, an approach consisting of a proteolytic digestion with subtilisin after protein precipitation was developed, eventually targeting a proteotypic and xenobiotic pentapeptide which is easily accessible to liquid chromatography- tandem mass spectrometry analysis. The method was validated for qualitative purposes and demonstrated to be specific, precise (relative standard deviations below 14%), sensitive (limit of detection 10 ng mL(-1)) and linear. Being simple, cost-effective and readily transferable to other doping control laboratories, a mass spectrometric assay for the detection of therapeutic concentrations of peginesatide in equine serum is, in terms of preventive doping research, applicable to routine analysis shortly after approval of the drug. PMID:22971699

Möller, Ines; Thomas, Andreas; Wingender, Anke; Machnik, Marc; Schänzer, Wilhelm; Thevis, Mario



Detection of myo-inositol trispyrophosphate in equine urine and plasma by hydrophillic interaction chromatography-tandem mass spectrometry.  


Myo-inositol trispyrophosphate (ITPP) is a new drug capable of increasing the amount of oxygen in hypoxic tissues. Studies have shown that administration of ITPP increases the maximal exercise capacity in normal mice as well as mice with severe heart failure. The properties of ITPP make it an ideal candidate as a doping agent to enhance performance in racehorses. While there have been speculations in the horseracing industry that the covert use of ITPP is already widespread, no reported method exists for the detection of ITPP in equine biological samples. ITPP is a difficult-to-detect drug due to its hydrophilic nature; the complexity of equine biological matrices also adds to the problem. This paper describes for the first time a method for the detection and confirmation of ITPP in equine urine and plasma. ITPP was isolated from the sample matrices by solid-phase extraction and the extract was analyzed by hydrophilic interaction chromatography-tandem mass spectrometry. ITPP could be detected at low ppb levels in both fortified equine plasma and urine with good precision, fast instrumental turnaround time, and negligible matrix interferences. To our knowledge, this is the first report of a validated method for the detection and unequivocal confirmation of low levels of ITPP in any biological fluid. PMID:22359395

Wong, April S Y; Ho, Emmie N M; Wan, Terence S M



Rapid and sensitive analysis of 3,4-methylenedioxypyrovalerone in equine plasma using liquid chromatography-tandem mass spectrometry.  


3,4-Methylenedioxypyrovalerone (MDPV) is a psychoactive drug with potent stimulant properties and potential for abuse and drug dependency. MDPV was recently classified as a Class I drug by Racing Commissioners International, indicating that it is a banned substance in equine athletes because it lacks therapeutic value in horses. To enforce this ban, a sensitive and fast liquid chromatography-tandem mass spectrometry method was needed. It is for this reason that this method was developed for quantification and confirmation of MDPV in equine plasma. Sample preparation involved liquid-liquid extraction. The analyte was analyzed by a triple-quadrupole linear ion trap mass spectrometer in positive multiple-reaction-monitoring and enhanced product ion scan modes. The method was validated for precision, accuracy, limit of detection (LOD), limit of quantification (LOQ), linearity, stability, extraction recovery, matrix effect, dilution accuracy and selectivity. The extraction recovery was >90%. The linearity range was from 5 to 15,000 pg/mL. LOD and LOQ were 2 and 5 pg/mL, respectively. Intra-day and inter-day accuracies were nearly 100%. The method is suitable for screening, quantification and confirmation of MDPV in equine plasma and has been successfully used to detect and confirm the presence of MDPV in equine plasma obtained post-competition. PMID:22582267

Wang, Caroline C; Hartmann-Fischbach, Petra; Krueger, Tim R; Wells, Terry L; Feineman, Amy R; Compton, Joanne C



A liquid chromatography-tandem mass spectrometry method for the detection of economically motivated adulteration in protein-containing foods.  


A new analytical method was developed to determine the presence of six (6) compounds with the potential to be used in economic adulteration to enhance the nitrogen content in milk products and bulk proteins. Residues were extracted from the matrix with 2% formic acid, after which acetonitrile (ACN) was added to induce precipitation of the proteins. Extracts were analyzed by liquid chromatography using a ZIC-HILIC column with tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). Single-laboratory method validation data was collected in six matrices fortified at concentrations down to 1.0 ?g/g (ppm). Average recoveries and average relative standard deviations (RSD) using spiked matrix calibration standard curves were the following: cyromazine (CY) 95.9% (7.5% RSD), dicyandiamide (DC) 98.1% (5.6% RSD), urea 102.5% (8.6% RSD), biuret (BU) 97.2% (6.6% RSD), triuret (TU) 97.7% (5.7% RSD), and amidinourea (AU) 93.4% (7.4% RSD). This method provides a rapid and effective approach to proactively combat economically motivated adulteration in protein-containing products. PMID:22197251

MacMahon, Shaun; Begley, Timothy H; Diachenko, Gregory W; Stromgren, Selen A



Proteomic analysis of human O {sup 6}-methylguanine-DNA methyltransferase by affinity chromatography and tandem mass spectrometry  

SciTech Connect

Recent evidence suggests that human O {sup 6}-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that protects the genome against mutagens and accords tumor resistance to many anticancer alkylating agents, may have other roles besides repair. Therefore, we isolated MGMT-interacting proteins from extracts of HT29 human colon cancer cells using affinity chromatography on MGMT-Sepharose. Specific proteins bound to this column were identified by electrospray ionization tandem mass spectrometry and/or Western blotting. These procedures identified >60 MGMT-interacting proteins with diverse functions including those involved in DNA replication and repair (MCM2, PCNA, ORC1, DNA polymerase {delta}, MSH-2, and DNA-dependent protein kinase), cell cycle progression (CDK1, cyclin B, CDK2, CDC7, CDC10, 14-3-3 protein, and p21{sup waf1/cip1}), RNA processing and translation (poly(A)-binding protein, nucleolin, heterogeneous nuclear ribonucleoproteins, A2/B1, and elongation factor-1{alpha}), several histones (H4, H3.4, and H2A.1), and topoisomerase I. The heat shock proteins, HSP-90{alpha} and {beta}, also bound strongly with MGMT. The DNA repair activity of MGMT was greatly enhanced in the presence of interacting proteins or histones. These data, for the first time, suggest that human MGMT is likely to have additional functions, possibly, in sensing and integrating the DNA damage/repair-related signals with replication, cell cycle progression, and genomic stability.

Niture, Suryakant K. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Doneanu, Catalin E. [Mass Spectrometry Center, Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195 (United States); Velu, Chinavenmeni S. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Bailey, Nathan I. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States); Srivenugopal, Kalkunte S. [Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106 (United States)]. E-mail:



Synthesis of substituted azafluorenones from dihalogeno diaryl ketones by palladium-catalyzed auto-tandem processes.  


Substituted azafluorenones were synthesized from different dihalogeno diaryl ketones under palladium catalysis by combining either Suzuki or Heck coupling with direct cyclizing arylation. Conditions were identified to allow both auto-tandem processes to proceed successfully from 3-(bromobenzoyl)- or 3-benzoyl-4-bromo-2-chloropyridines, as well as 4-benzoyl-2,3- and 4-benzoyl-2,5-dichloropyridines. PMID:25233952

Marquise, Nada; Dorcet, Vincent; Chevallier, Floris; Mongin, Florence



Tandem organic photovoltaics using both solution and vacuum deposited small molecules  

NASA Astrophysics Data System (ADS)

We demonstrate a tandem organic photovoltaic cell incorporating solution- and vacuum-deposited small molecules as the active layers. A blue and green-absorbing boron subphthalocyanine chloride:C70 graded heterojunction (HJ) sub-cell is combined with a green and red-absorbing functionalized squaraine/C70 bilayer HJ sub-cell, resulting in a tandem cell with a wavelength response from 350 nm to 800 nm. The efficiency of the cells depends on process conditions such as solvent annealing, resulting in nanocrystalline morphology that leads to improved charge and exciton transport compared with un-annealed cells. The incorporation of C70 in both sub-cells leads to an increase of short-circuit current by at least 30% compared to analogous cells using C60. The optimized power conversion efficiency of the tandem cell is 6.6% ± 0.1%, with an open-circuit voltage of 1.97 ± 0.1 V under simulated 1 sun, AM 1.5G illumination. The tandem cell voltage is equal to the sum of the constituent sub-cells, indicating that the transparent, Ag nanoparticle/MoO3 compound charge recombination layer interposed between the cells is nearly lossless.

Lassiter, Brian E.; Zimmerman, Jeramy D.; Panda, Anurag; Xiao, Xin; Forrest, Stephen R.



Identification and Characterization of Variable-Number Tandem Repeats in the Yersinia pestis Genome  

Microsoft Academic Search

Yersinia pestis, the infamous plague-causing pathogen, appears to have emerged in relatively recent history. Evidence of this fact comes from several studies that document a lack of nucleotide diversity in the Y. pestis ge- nome. In contrast, we report that variable-number tandem repeat (VNTR) sequences are common in the Y. pestis genome and occur frequently in gene coding regions. Larger




Nuclear breeder reactor fuel element with axial tandem stacking and getter  


A breeder reactor fuel element having a tandem arrangement of fissile and fertile fuel with a getter for fission product cesium disposed between the fissile and fertile sections. The getter is effective at reactor operating temperatures to isolate the cesium generated by the fissile material from reacting with the fertile fuel section.

Gibby, Ronald L. (Richland, WA); Lawrence, Leo A. (Kennewick, WA); Woodley, Robert E. (Richland, WA); Wilson, Charles N. (Richland, WA); Weber, Edward T. (Kennewick, WA); Johnson, Carl E. (Elk Grove, IL)



Binding of Dystrophin's Tandem Calponin Homology Domain to F-Actin Is Modulated by Actin's Structure  

E-print Network

Binding of Dystrophin's Tandem Calponin Homology Domain to F-Actin Is Modulated by Actin, Minneapolis, Minnesota 55455 USA ABSTRACT Dystrophin has been shown to be associated in cells with actin, includes two calponin-homology (CH) domains, and is similar to a large class of F-actin cross

Thomas, David D.


High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry  

SciTech Connect

The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.

McLuckey, S.A.; Goeringer, D.E.; Asano, K.G. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.



HF antennas for NVIS applications mounted to helicopters with tandem main rotor blades  

Microsoft Academic Search

Antennas mounted to helicopters for HF near-vertical incidence skywave (NVIS) communication suffer from severe rotor modulation at frequencies where the blades are nearly resonant. Helicopters with tandem main rotors such as the US Army Chinook cargo helicopter are considered. It is determined that there are two effects contributing to rotor modulation: the parasitic radiation from the rotor blades, and the

James E. Richie; Timothy Joda



Tandem reactions initiated by copper-catalyzed cross-coupling: a new strategy towards heterocycle synthesis.  


Copper-catalyzed cross-coupling reactions which lead to the formation of C-N, C-O, C-S and C-C bonds have been recognized as one of the most useful strategies in synthetic organic chemistry. During past decades, important breakthroughs in the study of Cu-catalyzed coupling processes demonstrated that Cu-catalyzed reactions are broadly applicable to a variety of research fields related to organic synthesis. Representatively, employing these coupling transformations as key steps, a large number of tandem reactions have been developed for the construction of various heterocyclic compounds. These tactics share the advantages of high atom economics of tandem reactions as well as the broad tolerance of Cu-catalyst systems. Therefore, Cu-catalyzed C-X (X = N, O, S, C) coupling transformation-initiated tandem reactions were quickly recognized as a strategy with great potential for synthesizing heterocyclic compounds and gained worldwide attention. In this review, recent research progress in heterocycle syntheses using tandem reactions initiated by copper-catalyzed coupling transformations, including C-N, C-O, C-S as well as C-C coupling processes are summarized. PMID:21879127

Liu, Yunyun; Wan, Jie-Ping



Selective Extraction of Free Astaxanthin from Haematococcus Culture Using a Tandem Organic Solvent System  

Microsoft Academic Search

A novel tandem solvent process of dodecane and methanol was developed for the selective extraction of free astaxanthin from red encysted Haematococcus culture. The process consists of dodecane extraction for astaxanthin mixture from the culture (stage 1) and methanol extraction for free astaxanthin from the dodecane extract (stage 2). In the first stage, astaxanthin mixture was directly extracted to dodecane

Chang Duk Kang; Sang Jun Sim



Genetic individualization of Cannabis sativa by a short tandem repeat multiplex system  

Microsoft Academic Search

Cannabis sativa is the most frequently used of all illicit drugs in the United States. Cannabis has been used throughout history for its stems in the production of hemp fiber, for its seed for oil and food, and for its buds and leaves as a psychoactive drug. Short tandem repeats (STRs), were chosen as molecular markers because of their distinct

Maria Angelica Mendoza Baez



Genetic Individualization of Cannabis sativa by a Short Tandem Repeat Multiplex System  

Microsoft Academic Search

Cannabis sativa is the most frequently used of all illicit drugs in the United States. Cannabis has been used throughout history for its stems in the production of hemp fiber, for its seed for oil and food, and for its buds and leaves as a psychoactive drug. Short tandem repeats (STRs), were chosen as molecular markers because of their distinct

Maria Angelica Mendoza Baez




EPA Science Inventory

Analysis of doxylamine N-oxide and pyrilamine N-oxide as synthetic standards and biologically derived metabolites by thermospray mass spectrometry (TSP/MS) provided (M + H)+ ions for each metabolite. TSP/tandem mass spectrometry (TSP/MS/MS) of the (M + H)+ ions provided fragment ...


Asymmetric synthesis of ?-alkylidene-?-hydroxy-?-butyrolactones via enantioselective tandem Michael-aldol reaction.  


A simple and efficient method for the asymmetric synthesis of ?-alkylidene-?-hydroxy-?-butyrolactones and related natural products was developed on the basis of the catalytic asymmetric tandem Michael-aldol reaction and simple transformations. The synthetic utility of this method was illustrated by the facile synthesis of trisubstituted ?-butyrolactone natural products. PMID:23252990

Lee, Sung Il; Jang, Jin Hee; Hwang, Geum-Sook; Ryu, Do Hyun



GENERAL TECHNICAL REPORT PSW-GTR-240 Tandem Selection for Fusiform Rust Disease  

E-print Network

GENERAL TECHNICAL REPORT PSW-GTR-240 216 Tandem Selection for Fusiform Rust Disease Resistance are intensively managed for short-term genetic gain. Fusiform rust disease, caused by the fungus Cronartium of the fusiform rust fungus at the U.S. Department of Agriculture Forest Service Resistance Screening Center

Standiford, Richard B.


Mechanism of constitutive activation of FLT3 with internal tandem duplication in the juxtamembrane domain  

Microsoft Academic Search

Internal tandem duplication (ITD) of the juxtamembrane (JM) domain of FLT3 is the most frequent mutation in human acute myeloid leukemia, and is significantly associated with leukocytosis and a poor prognosis. Previously we reported that FLT3 with ITD (FLT3\\/ITD) formed a homodimer and was autophosphorylated on tyrosine residues, while the mechanism remains unclear. In this study, we elucidated the role

Hitoshi Kiyoi; Ryuzo Ohno; Ryuzo Ueda; Hidehiko Saito; Tomoki Naoe



A Suboptimal Algorithm for De Novo Peptide Sequencing via Tandem Mass Spectrometry  

E-print Network

with high-performance liquid chromatography (HPLC) has been one of the most powerful techniques in protein of the current paper is to derive the original peptide sequence(s) for a given tandem mass spectrum of the distribution of isotopic carbons in the molecules; an ion may lose a water or an ammonia molecule and display

Chen, Ting


Advanced astigmatism-corrected tandem Wadsworth mounting for small-scale spectral broadband imaging spectrometer.  


Tandem gratings of double-dispersion mount make it possible to design an imaging spectrometer for the weak light observation with high spatial resolution, high spectral resolution, and high optical transmission efficiency. The traditional tandem Wadsworth mounting is originally designed to match the coaxial telescope and large-scale imaging spectrometer. When it is used to connect the off-axis telescope such as off-axis parabolic mirror, it presents lower imaging quality than to connect the coaxial telescope. It may also introduce interference among the detector and the optical elements as it is applied to the short focal length and small-scale spectrometer in a close volume by satellite. An advanced tandem Wadsworth mounting has been investigated to deal with the situation. The Wadsworth astigmatism-corrected mounting condition for which is expressed as the distance between the second concave grating and the imaging plane is calculated. Then the optimum arrangement for the first plane grating and the second concave grating, which make the anterior Wadsworth condition fulfilling each wavelength, is analyzed by the geometric and first order differential calculation. These two arrangements comprise the advanced Wadsworth mounting condition. The spectral resolution has also been calculated by these conditions. An example designed by the optimum theory proves that the advanced tandem Wadsworth mounting performs excellently in spectral broadband. PMID:23292378

Lei, Yu; Lin, Guan-yu



Functional b-propeller lectins by tandem duplications of repetitive units  

E-print Network

Functional b-propeller lectins by tandem duplications of repetitive units Itamar Yadid and Dan S proteins, b-propellers, which are made of 4­10 b-sheet units (blades) circularly arranged around a central- ducing the evolution of functional b-propellers by dupli- cation and fusion of repeated units remains

Tawfik, Dan S.


A machine learning approach to explore the spectra intensity pattern of peptides using tandem mass  

E-print Network

- 1 - A machine learning approach to explore the spectra intensity pattern of peptides using tandem-phase fragmentation of peptides is essential for the development of more reliable algorithms for high- throughput in 13878 different MS/MS spectra. The influence of a library of 35 features on peptide fragmentation

Feng, Jianfeng


Multiple-Locus Variable-Number Tandem Repeat Analysis Reveals Genetic Relationships within Bacillus anthracis  

Microsoft Academic Search

Bacillus anthracis is one of the most genetically homogeneous pathogens described, making strain discrim- ination particularly difficult. In this paper, we present a novel molecular typing system based on rapidly evolving variable-number tandem repeat (VNTR) loci. Multiple-locus VNTR analysis (MLVA) uses the com- bined power of multiple alleles at several marker loci. In our system, fluorescently labeled PCR primers are

P. Keim; L. B. Price; A. M. Klevytska; K. L. Smith; J. M. Schupp; R. Okinaka; P. J. Jackson; M. E. Hugh-Jones



Synthesis of ?-iodoketals from methyl ketones via sustainable and orthogonal tandem catalysis.  


A highly efficient method for the direct synthesis of ?-iodoketals from methyl ketones has been developed via sustainable integration of orthogonal tandem catalytic reactions: copper(II) oxide catalyzed iodination reaction and the subsequent excess or regenerated iodine catalyzed regioselective ketalization reaction. PMID:23313964

Yang, Yan; Gao, Meng; Shu, Wen-Ming; Wu, Liu-Ming; Zhang, Dong-Xue; Wu, An-Xin



Autosomal short tandem repeat genetic variation of the Basques in Spain  

E-print Network

50 Garcia o, Martin P, budowle b, uriarte J, albarran C, alonso a. basque Country autochthonous population data on 7 short tandem repeat loci. int J Legal Med. 1998;111:162-4. Medline:9587802 doi:10.1007/s004140050140 51 Garcia o, uriarte i, Martin...

Young, Kristin Leigh; Sun, Guangyun; Deka, Ranjan; Crawford, Michael H.



Extensive Allelic Variation among Francisella tularensis Strains in a Short-Sequence Tandem Repeat Region  

Microsoft Academic Search

Members of the genus Francisella and the species F. tularensis appear to be genetically very similar despite pronounced differences in virulence and geographic localization, and currently used typing methods do not allow discrimination of individual strains. Here we show that a number of short-sequence tandem repeat (SSTR) loci are present in F. tularensis genomes and that two of these loci,




Application of Experimental Design for Efficient Wind Tunnel Testing: The Tandem Wing MAV Case  

Microsoft Academic Search

Micro air vehicles (MAVs) are small scale unmanned aerial vehicles (UAVs) that are used for reconnaissance, intelligence gathering and battle damage assessment. The U.S. Air Force Research Lab Munitions Directorate develops MAVs for various defense missions. The case involves a tandem wing MAV that is designed to have retractable wings for transport, control surfaces on the aft wing, and two

Teresa Gail English



Heat-pipe liquid-pool-blanket concept for the Tandem Mirror Reactor  

SciTech Connect

The blanket concept for the tandem mirror reactor described in this paper was developed to produce the medium temperature heat (approx. 850 to 950 K) for the General Atomic sulfur-iodine thermochemical process for producing hydrogen. This medium temperature heat from the blanket constitutes about 81% of the total power output of the fusion reactor.

Hoffman, M.A.; Werner, R.W.; Johnson, G.L.



Generating Peptide Sequence Tags for Peptide Identification via Tandem Mass Spectrometry  

Microsoft Academic Search

Large-scale, rapid and accurate protein identification is the crucial basis for further protein analysis in computational proteomics. Searching protein database by use of the protein tandem mass spectra has been a standard solution for solving this problem. Though several algorithms have been proposed, more sensitive and accurate approaches are still needed. In this paper, an effective database search approach is

Changyong Yu; Guoren Wang; Yuhai Zhao; Keming Mao; Junjie Wu; Wendan Zhai



Peptide charge state determination of tandem mass spectra from low-resolution collision induced dissociation  

PubMed Central

Abstract Background Charge states of tandem mass spectra from low-resolution collision induced dissociation can not be determined by mass spectrometry. As a result, such spectra with multiple charges are usually searched multiple times by assuming each possible charge state. Not only does this strategy increase the overall database search time, but also yields more false positives. Hence, it is advantageous to determine charge states of such spectra before database search. Results We propose a new approach capable of determining the charge states of low-resolution tandem mass spectra. Four novel and discriminant features are introduced to describe tandem mass spectra and used in Gaussian mixture model to distinguish doubly and triply charged peptides. By testing on three independent datasets with known validity, the results have shown that this method can assign charge states to low-resolution tandem mass spectra more accurately than existing methods. Conclusions The proposed method can be used to improve the speed and reliability of peptide identification. PMID:22166140



Broader pattern of tandem repeats in the mitochondrial control region of Perciformes  

NASA Astrophysics Data System (ADS)

Perciformes, the largest order of vertebrates with 20 suborders, is the most diverse fish order that dominates vertebrate ocean life. The complete mitochondrial control region (CR) of Trichiurus japonicus (Trichiuridae, Scombroidei) and Pampus sp. (Stromateidae, Stromateoidei) were amplified and sequenced. Together with data from GenBank, the tandem repeats in the mitochondrial CR from 48 species, which covered nine suborders of Perciformes, are reported in this study. The tandem repeats tend to be long in the suborder Percoidei and Stromateoidei. The identical repeats in 21 species of Cichlidae suggest a common origin and have existed before species divergence. Larimichthys crocea shows tandem repeats instead of the typical structure of the central conserved sequence blocks, which was first reported in Perciformes and vertebrates. This might have resulted from interruption of the polymerase activity during the H-strand synthesis. The four broader patterns presented here for the tandem repeats, including those in both the 5' and 3' ends, only in the either 5' or 3' end, and in the central conserved domain of the control region, will be useful for understanding the evolution of species.

Cui, Zhaoxia; Liu, Yuan; Chu, Ka Hou



The ten years' operation of the HI-13 tandem accelerator at CIAE  

SciTech Connect

A summary of the ten years' operation of the HI-13 tandem accelerator at CIAE is presented. The particular emphasis is put on the improvements on the laddertron and high voltage divider resistor system. Some statistics on the machine operation and maintenance are also given.

Yang Bingfan; Qin Jiuchang; Zhang Canzhe; Hu Yueming; Guan Xialing; Jiang Yongliang; Zhang Guilian; Yang Weimin; Kan Chauxin; Yang Zhiren; Su Shengyong; Liu Dezhong; Wang Liyong; Zhu Jiazheng [Tandem Accelerator Laboratory, Department of Nuclear Physics, CIAE, P.O. Box 275(62), BeiJing 102413 (China)



Large-scale analysis of tandem repeat variability in the human genome.  


Tandem repeats are short DNA sequences that are repeated head-to-tail with a propensity to be variable. They constitute a significant proportion of the human genome, also occurring within coding and regulatory regions. Variation in these repeats can alter the function and/or expression of genes allowing organisms to swiftly adapt to novel environments. Importantly, some repeat expansions have also been linked to certain neurodegenerative diseases. Therefore, accurate sequencing of tandem repeats could contribute to our understanding of common phenotypic variability and might uncover missing genetic factors in idiopathic clinical conditions. However, despite long-standing evidence for the functional role of repeats, they are largely ignored because of technical limitations in sequencing, mapping and typing. Here, we report on a novel capture technique and data filtering protocol that allowed simultaneous sequencing of thousands of tandem repeats in the human genomes of a three generation family using GS-FLX-plus Titanium technology. Our results demonstrated that up to 7.6% of tandem repeats in this family (4% in coding sequences) differ from the reference sequence, and identified a de novo variation in the family tree. The method opens new routes to look at this underappreciated type of genetic variability, including the identification of novel disease-related repeats. PMID:24682812

Duitama, Jorge; Zablotskaya, Alena; Gemayel, Rita; Jansen, An; Belet, Stefanie; Vermeesch, Joris R; Verstrepen, Kevin J; Froyen, Guy



Results of radioisotope measurements at the NSF-University of Arizona tandem accelerator mass spectrometer facility  

Microsoft Academic Search

In this paper we will describe the operation of the University of Arizona tandem accelerator mass spectrometer (TAMS) facility, present results of some measurements performed to demonstrate the reliability of its performance, and describe several experiments which have been completed on samples of archaeologic and geophysical interest.

D. J. Donahue; A. J. T. Jull; T. H. Zabel



Detection of 10Be with a 2 MV tandem accelerator mass spectrometer  

Microsoft Academic Search

A technique is described in which a 2 MV tandem accelerator mass spectrometer is used to detect atoms of the radioisotope 10Be. The lower detection limit is shown to be about 10Be\\/9Be = 5 × 10-13. Results from measurements at lower terminal voltages are also presented.

T. H. Zabel; A. J. T. Jull; D. J. Donahue



Internal combustion engine with a central crankshaft and integral tandem annular pistons  

Microsoft Academic Search

An internal combustion engine with tandem annular pistons and a central crankshaft is disclosed, based on that found in British patent 11027 of 11 May 1914. The piston block formed by the two pistons presents, at each axial extremity, a double axial skirt fitted with an outer crown forming the head of the piston as such, and an inner crown

Bernard Esparbes



Characterization of a family of tandemly repeated DNA sequences in Triticeae.  


The recombinant plasmid dpTa1 has an insert of relic wheat DNA that represents a family of tandemly organized DNA sequences with a monomeric length of approximately 340 bp. This insert was used to investigate the structural organization of this element in the genomes of 58 species within the tribe Triticeae and in 7 species representing other tribes of the Poaceae. The main characteristic of the genomic organization of dpTa1 is a classical ladder-type pattern which is typical for tandemly organized sequences. The dpTa1 sequence is present in all of the genomes of the Triticeae species examined and in 1 species from a closely related tribe (Bromus inermis, Bromeae). DNA from Hordelymus europaeus (Triticeae) did not hybridize under the standard conditions used in this study. Prolonged exposure was necessary to obtain a weak signal. Our data suggest that the dpTa1 family is quite old in evolutionary terms, probably more ancient than the tribe Triticeae. The dpTa1 sequence is more abundant in the D-genome of wheat than in other genomes in Triticeae. DNA from several species also have bands in addition to the tandem repeats. The dpTa1 sequence contains short direct and inverted subrepeats and is homologous to a tandemly repeated DNA sequence from Hordeum chilense. PMID:24177832

Vershinin, A; Svitashev, S; Gummesson, P O; Salomon, B; von Bothmer, R; Bryngelsson, T



Making the Case for Objective Performance Metrics in Newborn Screening by Tandem Mass Spectrometry  

ERIC Educational Resources Information Center

The expansion of newborn screening programs to include multiplex testing by tandem mass spectrometry requires understanding and close monitoring of performance metrics. This is not done consistently because of lack of defined targets, and interlaboratory comparison is almost nonexistent. Between July 2004 and April 2006 (N = 176,185 cases), the…

Rinaldo, Piero; Zafari, Saba; Tortorelli, Silvia; Matern, Dietrich



PepSOM: An Algorithm for Peptide Identification by Tandem Mass Spectrometry Based on SOM  

Microsoft Academic Search

Peptide identification by tandem mass spectrometry is both an important and challenging prob- lem in proteomics. At present, huge amount of spectrum data are generated by high throughput mass spectrometers at a very fast pace, but algorithms to analyze these spectra are either too slow, not accurate enough, or only gives partial sequences or sequence tags. In this paper, we

Kang Ning; Hoong Kee Ng; Hon Wai Leong



In situ fabrication of polyacrylate-silver nanocomposite through photoinduced tandem reactions involving eosin dye  

E-print Network

1 In situ fabrication of polyacrylate-silver nanocomposite through photoinduced tandem reactions involving eosin dye Lavinia Balan a *, Jean-Pierre Malval a , Raphaël Schneider b , Didier Le Nouen c one-pot strategy involving eosin dye as visible sensitizer and an amine derivative as radicals source

Paris-Sud XI, Université de


J. Mol. Biol. (1978) 126, 53-71 Tandem Genetic Duplications in Salmonella typhimurium  

E-print Network

J. Mol. Biol. (1978) 126, 53-71 Tandem Genetic Duplications in Salmonella typhimurium AND .I. R. ROTH co& and Salmonella typhimurium (Langridge. 1969; Miller $ Roth. 1971; Hill & Combriato of the histidine operon in Salmonella have previously been described. One is based upon the ability of duplica

California at Davis, University of


-7. Mol. Biol. (1978) 119, 147-166 Tandem Chromosomal Duplications in Salmonella typhimurium  

E-print Network

-7. Mol. Biol. (1978) 119, 147-166 Tandem Chromosomal Duplications in Salmonella typhimurium University of Utah ASalt Lake City, Utah 84112, U.S'.A. (Received 16 August 1977) Salmonella strains are merodiploid for large regions (up to 25%) of the Salmonella genome. (4) Recipient strains that inherit the His

California at Davis, University of


The Tandem Affinity Purification (TAP) Method: A General Procedure of Protein Complex Purification  

Microsoft Academic Search

Identification of components present in biological complexes requires their purification to near homogeneity. Methods of purification vary from protein to protein, making it impossible to design a general purification strategy valid for all cases. We have developed the tandem affinity purification (TAP) method as a tool that allows rapid purification under native conditions of complexes, even when expressed at their

Oscar Puig; Friederike Caspary; Guillaume Rigaut; Berthold Rutz; Emmanuelle Bouveret; Elisabeth Bragado-Nilsson; Matthias Wilm; Bertrand Séraphin



Vehicle Dispatching Problem at the Container Terminal with Tandem Lift Quay Cranes  

E-print Network

’ operation schedules and the vehicles’ delivery schedules. The static version of the problem can be formulated as an MILP model and it is a combinational optimization problem. When the type of QC is tandem lift, the problem becomes more complicated because...

Xing, Yao



Pyridone Annulation via Tandem Curtius Rearrangement/6?-Electrocyclization: Total Synthesis of (-)-Lyconadin C  

PubMed Central

A concise, enantioselective total synthesis of the Lycopodium alkaloid (?)-lyconadin C was achieved in 12 steps and high overall yield. Key features include construction of a luciduline congener through Mannich-type cyclization and a one-pot, tandem Curtius rearrangement/6?-electrocyclization to fashion the 2-pyridone system of lyconadin C. PMID:23909645

Cheng, Xiayun



Pyridone annulation via tandem Curtius rearrangement/6?-electrocyclization: total synthesis of (-)-lyconadin C.  


A concise, enantioselective total synthesis of the Lycopodium alkaloid (-)-lyconadin C was achieved in 12 steps and high overall yield. Key features include construction of a luciduline congener through Mannich-type cyclization and a one-pot, tandem Curtius rearrangement/6?-electrocyclization to fashion the 2-pyridone system of lyconadin C. PMID:23909645

Cheng, Xiayun; Waters, Stephen P



Extension to the 350-kV negative ion injector for the JAERI tandem accelerator  

NASA Astrophysics Data System (ADS)

An extension to the 350-kV negative ion injector for the JAERI tandem accelerator was constructed to minimize loss of the beam time due to changing and tuning the ion sources, and to improve substantially the reliability and personal safety in the accelerator operation. Performance during the first operation over three months is reported and discussed in comparison with the previous performance.

Minehara, Eisuke; Yoshida, Tadashi; Abe, Shinichi; Kanazawa, Shuhei; Tsukihashi, Yoshihiro; Horie, Katsuzo; Hanashima, Susumu



Ion Cyclotron Resonant Heating slot antenna for the Tandem Mirror Experiment-Upgrade  

SciTech Connect

The Ion Cyclotron Resonant Heating (ICRH) slot antenna has been a part of the ion and electron plasma heating system in the central cell region of the Tandem Mirror Experiment-Upgrade (TMX-U). This paper presents the mechanical design and arrangement of the antenna, coax feed lines, feedthroughs, and matching network for the slot antenna.

Brooksby, C.A.; Calderson, M.O.; Cummins, W.F.; Ferguson, S.W.; Williamson, V.L.



Focusing twist reflector for electron-cyclotron resonance heating in the Tandem Mirror Experiment-Upgrade  

SciTech Connect

A twist reflector plate is described that linearly polarizes and focuses the TE/sub O/sub 1// circular waveguide mode for heating hot electrons in the thermal barrier of the Tandem Mirror Experiment-Upgrade (TMX-U). The plate polarizing efficiency is 95%, and it has operated satisfactorily at 150 kW power level.

Stallard, B.W.; Coffield, F.E.; Felker, B.; Taska, J.; Christensen, T.E.; Gallagher, N.C. Jr.; Sweeney, D.W.



Diversity of Potential Short Tandem Repeats in Mycobacterium leprae and Application for Molecular Typing  

Microsoft Academic Search

A recent advance in molecular typing for tracing the transmission of leprosy is the discovery of short tandem repeats (STRs) in Mycobacterium leprae. To substantiate polymorphic loci from STR as promising candidates for molecular typing tools in leprosy epidemiology, 44 STR loci including 33 microsatellites and 11 minisat- ellites were investigated among 27 laboratory strains by sequencing PCR products. Not

Liangfen Zhang; Teky Budiawan; Masanori Matsuoka



Targeted tandem affinity purification of PSD95 recovers core postsynaptic complexes and schizophrenia susceptibility proteins  

Microsoft Academic Search

The molecular complexity of mammalian proteomes demands new methods for mapping the organization of multiprotein complexes. Here, we combine mouse genetics and proteomics to characterize synapse protein complexes and interaction networks. New tandem affinity purification (TAP) tags were fused to the carboxyl terminus of PSD-95 using gene targeting in mice. Homozygous mice showed no detectable abnormalities in PSD-95 expression, subcellular

Esperanza Fernández; Mark O Collins; Rachel T Uren; Maksym V Kopanitsa; Noboru H Komiyama; Mike D R Croning; Lysimachos Zografos; J Douglas Armstrong; Jyoti S Choudhary; Seth G N Grant



Confirmatory analysis of firocoxib in bovine milk by rapid resolution liquid chromatography tandem mass spectrometry  

Microsoft Academic Search

A rapid method has been developed to analyse for firocoxib (FIRO) residue in bovine milk. Milk samples were extracted with acetonitrile and sample extracts were purified on Evolute™ ABN solid phase extraction cartridges. Aliquots were analysed by rapid resolution liquid chromatography tandem mass spectrometry (RRLC–MS\\/MS). The method was validated in bovine milk, according to the criteria defined in Commission Decision

Geraldine Dowling; Pasquale Gallo; Liam Regan



Direct Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass  

E-print Network

diseases caused by enzyme deficiencies in the heme biosynthetic pathway.1 Heme biosynthesis starts from disease caused by alcoholism, hepatitis C, or estrogen intake by women. The PCT manifests itselfDirect Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass

Gelb, Michael


Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing  

Microsoft Academic Search

Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiOx) layer separates and connects the front cell and the back cell.

Jin Young Kim; Kwanghee Lee; Nelson E. Coates; Daniel Moses; Thuc-Quyen Nguyen; Mark Dante; Alan J. Heeger



On de novo interpretation of tandem mass spectra for peptide identification  

Microsoft Academic Search

The correct interpretation of tandem mass spectra is a difficult problem, even when it is limited to scoring peptides against a database. De novo sequencing is considerably harder, but critical when sequence databases are incomplete or not available. In this paper we build upon earlier work due to Dancik et al., and Chen et al. to provide a dynamic programming

Vineet Bafna; Nathan Edwards



Modelling single- and tandem-bubble dynamics between two parallel plates for biomedical applications  

PubMed Central

Carefully timed tandem microbubbles have been shown to produce directional and targeted membrane poration of individual cells in microfluidic systems, which could be of use in ultrasound-mediated drug and gene delivery. This study aims at contributing to the understanding of the mechanisms at play in such an interaction. The dynamics of single and tandem microbubbles between two parallel plates is studied numerically and analytically. Comparisons are then made between the numerical results and the available experimental results. Numerically, assuming a potential flow, a three-dimensional boundary element method (BEM) is used to describe complex bubble deformations, jet formation, and bubble splitting. Analytically, compressibility and viscous boundary layer effects along the channel walls, neglected in the BEM model, are considered while shape of the bubble is not considered. Comparisons show that energy losses modify the bubble dynamics when the two approaches use identical initial conditions. The initial conditions in the boundary element method can be adjusted to recover the bubble period and maximum bubble volume when in an infinite medium. Using the same conditions enables the method to recover the full dynamics of single and tandem bubbles, including large deformations and fast re-entering jet formation. This method can be used as a design tool for future tandem-bubble sonoporation experiments. PMID:24293683

Hsiao, C.-T.; Choi, J.-K.; Singh, S.; Chahine, G. L.; Hay, T. A.; Ilinskii, Yu. A.; Zabolotskaya, E. A.; Hamilton, M. F.; Sankin, G.; Yuan, F.; Zhong, P.



Structure of a Longitudinal Actin Dimer Assembled by Tandem W Domains: Implications for Actin Filament Nucleation  

SciTech Connect

Actin filament nucleators initiate polymerization in cells in a regulated manner. A common architecture among these molecules consists of tandem WASP homology 2 domains (W domains) that recruit three to four actin subunits to form a polymerization nucleus. We describe a low-resolution crystal structure of an actin dimer assembled by tandem W domains, where the first W domain is cross-linked to Cys374 of the actin subunit bound to it, whereas the last W domain is followed by the C-terminal pointed end-capping helix of thymosin {beta}4. While the arrangement of actin subunits in the dimer resembles that of a long-pitch helix of the actin filament, important differences are observed. These differences result from steric hindrance of the W domain with intersubunit contacts in the actin filament. We also determined the structure of the first W domain of Vibrio parahaemolyticus VopL cross-linked to actin Cys374 and show it to be nearly identical with non-cross-linked W-Actin structures. This result validates the use of cross-linking as a tool for the study of actin nucleation complexes, whose natural tendency to polymerize interferes with most structural methods. Combined with a biochemical analysis of nucleation, the structures may explain why nucleators based on tandem W domains with short inter-W linkers have relatively weak activity, cannot stay bound to filaments after nucleation, and are unlikely to influence filament elongation. The findings may also explain why nucleation-promoting factors of the Arp2/3 complex, which are related to tandem-W-domain nucleators, are ejected from branch junctions after nucleation. We finally show that the simple addition of the C-terminal pointed end-capping helix of thymosin {beta}4 to tandem W domains can change their activity from actin filament nucleation to monomer sequestration.

Rebowski, Grzegorz; Namgoong, Suk; Boczkowska, Malgorzata; Leavis, Paul C.; Navaza, Jorge; Dominguez, Roberto (IBS) [IBS; (BBRI); (UPENN-MED)



Balance in essential tremor during tandem gait: is the first mis-step an important finding?  


Essential tremor (ET) is the most commonly diagnosed movement disorder. ET may cause substantial loss of motor skills and balance with advanced age. We compared abnormalities in tandem gait with daily activity and Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) scores in 90 ET patients. All patients performed a 15-step tandem three times. The mean of first mis-steps was accepted as the tandem index (TI). The mean age was 61.4 ± 17 years; the mean duration of tremor was 6.7 ± 4 years; and there were 36 men and 54 women. There was no significant difference for age or sex between patients and controls. Head (24.6%), jaw (5.5%), voice (11%), and tongue tremors (1.5%) were identified in ET patients. Rest (2.5%), postural (95%), and kinetic tremors (54%) were detected in the upper extremities. Postural tremor was found in the lower extremities of 5%. The mean TI was 8.3 ± 4 (median, 8) in ET patients, and 10.6 ± 3.9 (median, 10) in controls (p=0.04). Correlation analysis of TI and FTMTRS scores showed tandem gait was significantly correlated with age, total tremor score, postural and kinetic extremity tremor, writing, drawing, pouring, feeding, and working scores. Linear regression showed a significant effect of age and FTMTRS score on TI. The decrease in balance control is apparent with advancing age. Balance disorders were more pronounced in ET patients. Although first mis-step in tandem gait is not as detailed as dynamic balance tests, it can be a simple method for detecting balance disorders. PMID:23953429

Cinar, N; Sahin, S; Okluoglu Onay, T; Karsidag, S



Randomized Trial of Oral Misoprostol Treatment for Cervical Ripening Before Tandem Application in Cervix Cancer  

SciTech Connect

Purpose: To investigate the efficacy of oral misoprostol administered to facilitate tandem application to the cervix as a part of brachytherapy in patients with cervical cancer. Methods and Materials: Eighty patients with cervical cancer who had been planned to undergo brachytherapy at Dr. Luetfi Kirdar Kartal Training and Research Hospital were evaluated in a double-blind, prospective, randomized trial. Patients were divided randomly into two groups of 40 patients. The first and second groups received 400 {mu}g of misoprostol orally and placebo, respectively, 3 h before tandem application. The two groups were compared in terms of age, diameter of tumor, parity, age at first intercourse, amount of bleeding and pain at first tandem application, length of endometrial cavity measured by hysterometer, and size of Hegar dilators used for cervical dilatation. Results: Of all cases, 63.6%, 16.3%, 10%, 6.3%, 2.5%, and 1.3% were Stage IIB, IIIB, IIIA, IVA, IIA and IIC, respectively. Mean ({+-}SD) age (range) was 49.3 {+-} 13.1 (25-83) years and 56.6 {+-} 13.2 (30-78) years in the study and control groups, respectively (p = 0.015). Age at first intercourse, diameter of tumor, parity, amount of bleeding at first tandem application, and length of endometrial cavity measured by hysterometer were not significantly different between the two groups. Pain score was significantly higher in the control group (p < 0.001). Application was significantly easier in the study group compared with controls (p < 0.001). Average size of initial Hegar dilators used for cervical dilatation was significantly higher in the study group compared with controls (p = 0.017). Conclusion: Administration of misoprostol 400 {mu}g orally for cervical ripening before tandem application facilitates the procedure, increases patient tolerability and comfort, and may decrease complication rates.

Cepni, Kimia; Gul, Sule [Department of Radiation Oncology, Ministry of Health, Dr. Lutfi Kirdar Kartal Training and Research Hospital, Istanbul (Turkey); Cepni, Ismail [Department of Obstetrics and Gynecology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Gueralp, Onur, E-mail: [Department of Obstetrics and Gynecology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Sal, Veysel [Department of Obstetrics and Gynecology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul (Turkey); Mayadagli, Alpaslan [Department of Radiation Oncology, Ministry of Health, Dr. Lutfi Kirdar Kartal Training and Research Hospital, Istanbul (Turkey)



Specific Tandem Repeats Are Sufficient for Paramutation-Induced Trans-Generational Silencing  

PubMed Central

Paramutation is a well-studied epigenetic phenomenon in which trans communication between two different alleles leads to meiotically heritable transcriptional silencing of one of the alleles. Paramutation at the b1 locus involves RNA-mediated transcriptional silencing and requires specific tandem repeats that generate siRNAs. This study addressed three important questions: 1) are the tandem repeats sufficient for paramutation, 2) do they need to be in an allelic position to mediate paramutation, and 3) is there an association between the ability to mediate paramutation and repeat DNA methylation levels? Paramutation was achieved using multiple transgenes containing the b1 tandem repeats, including events with tandem repeats of only one half of the repeat unit (413 bp), demonstrating that these sequences are sufficient for paramutation and an allelic position is not required for the repeats to communicate. Furthermore, the transgenic tandem repeats increased the expression of a reporter gene in maize, demonstrating the repeats contain transcriptional regulatory sequences. Transgene-mediated paramutation required the mediator of paramutation1 gene, which is necessary for endogenous paramutation, suggesting endogenous and transgene-mediated paramutation both require an RNA-mediated transcriptional silencing pathway. While all tested repeat transgenes produced small interfering RNAs (siRNAs), not all transgenes induced paramutation suggesting that, as with endogenous alleles, siRNA production is not sufficient for paramutation. The repeat transgene-induced silencing was less efficiently transmitted than silencing induced by the repeats of endogenous b1 alleles, which is always 100% efficient. The variability in the strength of the repeat transgene-induced silencing enabled testing whether the extent of DNA methylation within the repeats correlated with differences in efficiency of paramutation. Transgene-induced paramutation does not require extensive DNA methylation within the transgene. However, increased DNA methylation within the endogenous b1 repeats after transgene-induced paramutation was associated with stronger silencing of the endogenous allele. PMID:24146624

Bader, Rechien; Arteaga-Vazquez, Mario A.; Chandler, Vicki L.



Enhanced suicide gene therapy by chimeric tumor-specific promoter based on HSF1 transcriptional regulation  

Microsoft Academic Search

Two tandem cassettes, one containing the telomerase reverse transcriptase gene (hTERT) promoter upstream of a constitutively activated form of heat shock transcription factor 1 (cHSF1) and followed by the other containing the heat shock protein 70B (hsp70B) promoter (HSE) upstream of the cytosine deaminase (CD) gene, could greatly enhance the efficiency of CD gene therapy while retaining tumor specificity in

Jinhui Wang; Mingzhong Yao; Zilai Zhang; Jinfa Gu; Yanhong Zhang; Binhua Li; Lanying Sun; Xinyuan Liu



Enhancing bioremediation  

SciTech Connect

Oxygen is often the limiting factor in aerobic bioremediation. Without adequate oxygen, contaminant degradation will either cease or proceed by highly inefficient anaerobic processes. Researchers at Regenesis Bioremediation Products recently develope a technology to combat this problem, Oxygen Release Compound (ORC) a unique formulation of magnesium peroxide release oxygen slowly when hydrated. ORC is idea for supporting bioremediation of underground storage tank releases. ORC treatment represents a low intensity approach to remediation - simple, passive, low-cost, long term enhancement of a natural attenuation. 1 fig.

Koenigsberg, S. [National Univ., Irvine, CA (United States)



Structures of Naturally Evolved CUP1 Tandem Arrays in Yeast Indicate That These Arrays Are Generated by Unequal Nonhomologous Recombination  

PubMed Central

An important issue in genome evolution is the mechanism by which tandem duplications are generated from single-copy genes. In the yeast Saccharomyces cerevisiae, most strains contain tandemly duplicated copies of CUP1, a gene that encodes a copper-binding metallothionein. By screening 101 natural isolates of S. cerevisiae, we identified five different types of CUP1-containing repeats, as well as strains that only had one copy of CUP1. A comparison of the DNA sequences of these strains indicates that the CUP1 tandem arrays were generated by unequal nonhomologous recombination events from strains that had one CUP1 gene. PMID:25236733

Zhao, Ying; Strope, Pooja K.; Kozmin, Stanislav G.; McCusker, John H.; Dietrich, Fred S.; Kokoska, Robert J.; Petes, Thomas D.



XTandem Parser: an open-source library to parse and analyse X!Tandem MS/MS search results.  


Identification of proteins by MS plays an important role in proteomics. A crucial step concerns the identification of peptides from MS/MS spectra. The X!Tandem Project ( supplies an open-source search engine for this purpose. In this study, we present an open-source Java library called XTandem Parser that parses X!Tandem XML result files into an easily accessible and fully functional object model ( In addition, a graphical user interface is provided that functions as a usage example and an end-user visualization tool. PMID:20140905

Muth, Thilo; Vaudel, Marc; Barsnes, Harald; Martens, Lennart; Sickmann, Albert



Enhancing Education  

NSDL National Science Digital Library

Educators who are interested in incorporating new technologies into their classroom experience often wonder where to start. They may want to start by visiting the Enhancing Education site, which is maintained by staff members at the Columbia Center for New Media Teaching and Learning at Columbia University. The site is organized a bit like a weblog, as there are different posts organized into subjects that include "Noted", "Solutions", and "Primers". The "Noted" postings highlight interesting technologies that may be of interest to educators, and the "Solutions" entries are composed of a quick "how-to" that addresses a broad range of technologies and approaches to classroom learning. Finally, the "Primers" posts cover the basic elements of a compelling new technology or idea, including incorporating a weblog into the class or peer editing. Visitors can also view the top ten tags on the site, or take a look at the most recent posts.


Power generation of series and series/parallel triple junction tandem solar cells derived from measured spectra in Japan  

NASA Astrophysics Data System (ADS)

A limiting efficiency of a solar cell changes according to the incident solar spectrum. With respect to a two-terminal triple junction tandem solar cell and interconnection of individual cells within it, the variation of limiting efficiency of a modified triple-tandem solar cell, in which two series-connected bottom cells are connected in parallel to the top cell, is lower than that of a conventional fully series-connected tandem cell. We calculate limiting efficiency of these two structures using measured solar spectra and meteorological condition at four different locations in Japan. It is shown that a triple junction tandem cell in a combination of series and parallel connections generates 7% larger amount of power than a series-connected cell does in average if these cells are optimized at airmass (AM) 1.5.

Naito, Shunya; Okada, Yoshitaka



Facile tandem Suzuki coupling/transfer hydrogenation reaction with a bis-heteroscorpionate Pd-Ru complex.  


Design and synthesis of the bis(pyrazol-1-yl)methane based bis-heteroscorpionate Pd-Ru complex results in efficient tandem Suzuki coupling/transfer hydrogenation reaction with a broad range of substrate reactivity. PMID:25297718

Dehury, Niranjan; Tripathy, Suman Kumar; Sahoo, Anupam; Maity, Niladri; Patra, Srikanta




EPA Science Inventory

Phthalate determination is important because phthalates often are major impurities in samples and can have significant health effects. Tandem mass spectrometry under chemical ionization mass spectrometry conditions with isobutane as the reagent gas was used to determine 11 phthal...


Small tandemly repeated DNA sequences of higher plants likely originate from a tRNA gene ancestor.  

PubMed Central

Several monomers (177 bp) of a tandemly arranged repetitive nuclear DNA sequence of Brassica oleracea have been cloned and sequenced. They share up to 95% homology between one another and up to 80% with other satellite DNA sequences of Cruciferae, suggesting a common ancestor. Both strands of these monomers show more than 50% homology with many tRNA genes; the best homologies have been obtained with Lys and His yeast mitochondrial tRNA genes (respectively 64% and 60%). These results suggest that small tandemly repeated DNA sequences of plants may have evolved from a tRNA gene ancestor. These tandem repeats have probably arisen via a process involving reverse transcription of polymerase III RNA intermediates, as is the case for interspersed DNA sequences of mammalians. A model is proposed to explain the formation of such small tandemly repeated DNA sequences. Images PMID:3774553

Benslimane, A A; Dron, M; Hartmann, C; Rode, A



Simultaneous determination of flunitrazepam and 7-aminoflunitrazepam in human serum by ion trap gas chromatography–tandem mass spectrometry  

Microsoft Academic Search

A method for the determination of flunitrazepam (FNZ) and 7-aminoflunitrazepam (7-AFNZ) in human serum was developed with ion trap gas chromatography (GC)–tandem mass spectrometry. The 7-AFNZ was derivatizated with 50?l trifluoroacetic anhydride (TFAA), 60°C-20min. EI mass spectra and tandem mass spectra of FNZ and 7-AFNZ-TFA were m\\/z 238, 239, 266, 286, 294, 312, 313(M+), m\\/z 350, 351, 360, 378, 379(M+),

Masaru Terada; Sousuke Masui; Takeshi Hayashi; Ritsuko Watanabe; Hiromasa Inoue; Morio Iino; Masato Nakatome; Ryoji Matoba; Tatsuo Shinozuka; Tatsuya Murai; Einosuke Tanaka; Katsuya Honda



A compatible exon-exon junction database for the identification of exon skipping events using tandem mass spectrum data  

Microsoft Academic Search

BACKGROUND: Alternative splicing is an important gene regulation mechanism. It is estimated that about 74% of multi-exon human genes have alternative splicing. High throughput tandem (MS\\/MS) mass spectrometry provides valuable information for rapidly identifying potentially novel alternatively-spliced protein products from experimental datasets. However, the ability to identify alternative splicing events through tandem mass spectrometry depends on the database against which

Fan Mo; Xu Hong; Feng Gao; Lin Du; Jun Wang; Gilbert S. Omenn; Biaoyang Lin



Testosterone Measurement by Isotope-Dilution Liquid Chromatography-Tandem Mass Spectrometry: Validation of a Method for Routine Clinical Practice  

Microsoft Academic Search

Background: Immunoassay is unsatisfactory for mea- suring the testosterone concentrations typically found in women. Bench-top tandem mass spectrometers are a viable alternative technology for measurements in the clinical laboratory. Methods: We used stable-isotope dilution liquid chro- matography-tandem mass spectrometry (ID\\/LC-MS\\/ MS) to measure testosterone in plasma and serum. The sample volume was 50 L in duplicate; preparation and analysis were

Marion L. Cawood; Helen P. Field; Clive G. Ford; Scott Gillingwater; Andrew Kicman; David Cowan; Julian H. Barth


Design of a tandem target for a simultaneous production of C-11 and F-18 with 18 MeV  

Microsoft Academic Search

A tandem target for the simultaneous production of [18F]-fluoride and [11C]CH4 with 18 MeV protons has been manufactured and evaluated. Tungsten was chosen as a grid material because of its good mechanical and thermal properties. Four tungsten grids were placed between the liquid target cavities and between the air cooling units. This tandem target system showed a stable production yield

Min Goo Hur; Sang Wook Kim; Seung Dae Yang; In Su Jung; Tae Keun Yang; Hong Suk Chang; Bong Hwan Hong; Joon Sun Kang; Dong Hyun An; Jong-Seo Chai; Kook Hyun Yu



Design of a tandem target for a simultaneous production of C-11 and F-18 with 18 MeV  

Microsoft Academic Search

A tandem target for the simultaneous production of [18F]-fluoride and [11C]CH4 with 18MeV protons has been manufactured and evaluated. Tungsten was chosen as a grid material because of its good mechanical and thermal properties. Four tungsten grids were placed between the liquid target cavities and between the air cooling units. This tandem target system showed a stable production yield and

Min Goo Hur; Sang Wook Kim; Seung Dae Yang; In Su Jung; Tae Keun Yang; Hong Suk Chang; Bong Hwan Hong; Joon Sun Kang; Dong Hyun An; Jong-Seo Chai; Kook Hyun Yu



High-efficiency orange and tandem white organic light-emitting diodes using phosphorescent dyes with horizontally oriented emitting dipoles.  


Tandem white organic light-emitting diodes (WOLEDs) using horizontally oriented phosphorescent dyes in an exciplex-forming co-host are presented, along with an orange OLED. A high external quantum efficiency of 32% is achieved for the orange OLED at 1000 cd m(-2) and the tandem WOLEDs exhibit a high maximum EQE of 54.3% (PE of 63 lm W(-1)). PMID:24923483

Lee, Sunghun; Shin, Hyun; Kim, Jang-Joo



Nuclear Magnetic Resonance-Based Dissection of a Glycosyltransferase Specificity for the Mucin MUC1 Tandem Repeat †  

Microsoft Academic Search

The human glycoprotein MUC1 mucin plays a critical role in cancer progression. Breast, ovarian, and colon cancer cells often display unique cell-surface antigens corresponding to aberrantly glycosylated forms of the MUC1 tandem repeat. In this report, 15N- and 13C-labeled forms of a recombinant MUC1 construct containing five tandem repeats were used as substrates to define the order and kinetics of

Richard D. Brokx; Leigh Revers; Qinghong Zhang; Shaoxian Yang; Tapas K. Mal; Mitsuhiko Ikura; Jean Gariépy



The biological effects of simple tandem repeats: Lessons from the repeat expansion diseases  

PubMed Central

Tandem repeats are common features of both prokaryote and eukaryote genomes, where they can be found not only in intergenic regions but also in both the noncoding and coding regions of a variety of different genes. The repeat expansion diseases are a group of human genetic disorders caused by long and highly polymorphic tandem repeats. These disorders provide many examples of the effects that such repeats can have on many biological processes. While repeats in the coding sequence can result in the generation of toxic or malfunctioning proteins, noncoding repeats can also have significant effects including the generation of chromosome fragility, the silencing of the genes in which they are located, the modulation of transcription and translation, and the sequestering of proteins involved in processes such as splicing and cell architecture. PMID:18593815

Usdin, Karen



Tandem and triple-junction polymer:nanocrystal hybrid solar cells consisting of identical subcells.  


Tandem and triple-junction polymer:nanocrystal hybrid solar cells with identical subcells based on P3HT:CdSe nanocrystal bulk heterojunctions (BHJs) are reported for the first time showing 2-fold and 3-fold increases of open-circuit voltage (VOC), respectively, relative to the single-junction cell. A combination of nanocrystalline ZnO and pH-neutral PEDOT:PSS is used as the interconnecting layer, and the thicknesses of subcells are optimized with the guidance of optical simulations. As a result, the average power conversion efficiency (PCE) exhibits a significant increase from 2.0% (VOC = 0.57 V) in single-junction devices to 2.7% (champion 3.1%, VOC = 1.28 V) in tandem devices and 2.3% (VOC = 1.98 V) in triple-junction devices. PMID:25233268

Lu, Haipeng; Bartynski, Andrew N; Greaney, Matthew J; Thompson, Mark E; Brutchey, Richard L



Tandem Mirror Experiment Upgrade (TMX-U) overview-recent events  

SciTech Connect

Since its construction and commissioning was completed in the winter of 1981, the Tandem Mirror Experiment Upgrade (TMX-U) has been conducting tandem mirror thermal barrier experiments. The work, following the fall of 1983 when strong plugging with thermal barriers was achieved, has been directed toward controlling radial transport and forming thermal barriers with high density and Beta. This paper describes the overall engineering component of these efforts. Major changes to the machine have included vacuum improvements, changes to the Electron and Ion Cyclotron Resonance Heating systems (ECRH and ICRH), and the installation of a Plasma Potential Control system (PPC) for radial transport reduction. TMX-U operates an extensive diagnostics system that acquires data from 21 types of diagnostic instruments with more than 600 channels, in addition to 246 machine parameters. The changes and additions will be presented. The closing section of this paper will describe the initial study work for a proposed TMX-U octupole configured machine.

Calderon, M.O.; Bell, H.H.



Experimental studies of the rotational stability of a tandem mirror with quadrupole end cells  

SciTech Connect

It is demonstrated that the radial electric field in the Phaedrus Tandem Mirror ({ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Nuclear} {ital Fusion} {ital Research} 1984 (IAEA, Vienna, 1985), Vol. 2, p. 265) can be altered using plasma potential control rings (PPC rings) situated at each end of the device, and the azimuthal plasma rotational velocity may thus be varied. Low-frequency ({omega}{much lt}{omega}{sub {ital ci}}), low azimuthal mode number ({ital m}={minus}1 and {ital m}={minus}2) instabilities driven by {bold E}{times}{bold B} rotation are observed and shown to be in qualitative agreement with the theory of Freidberg and D'Ippolito (Phys. Fluids {bold 26}, 2657 (1983)), and Phillips (Phys. Fluids {bold 27}, 1783 (1984)) for the case when Phaedrus is operated as a conventional tandem mirror with minimum-{vert bar}{ital B}{vert bar} end cells.

Severn, G.D.; Hershkowitz, N.; Breun, R.A.; Ferron, J.R. (Department of Nuclear Engineering and Engineering Physics, University of Wisconsin, Madison, Wisconsin 53706 (US))



Focusing of tandem bistatic SAR data using the chirp-scaling algorithm  

NASA Astrophysics Data System (ADS)

Based on an exact analytical bistatic point target spectrum, an efficient chirp-scaling algorithm is proposed to correct the range cell migration of different range gates to the one of the reference range for tandem bistatic synthetic aperture radar data processing. The length of the baseline (baseline to range ratio) does not give a direct influence to the proposed algorithm, which can be applied to the processing of tandem bistatic data with a large baseline even when the baseline is equal to the range. No interpolation is needed during the entire processing, only fast Fourier transforms and phase multiplications are needed, which result in efficiency. The validity of the proposed algorithm has been verified by simulated experiments.

Chen, Shichao; Xing, Mengdao; Zhou, Song; Zhang, Lei; Bao, Zheng



Rapid method for Mycobacterium tuberculosis identification using electrospray ionization tandem mass spectrometry analysis of mycolic acids.  


Mycolic acids (MAs), which play a crucial role in the architecture of mycobacterial cell walls, were analyzed using electrospray ionization tandem mass spectrometry. A targeted analysis based on the 10 most abundant and characteristic multiple reaction monitoring pairs was used to profile the crude fatty acid mixtures from Mtb and several nontuberculous mycobacterial strains. Comparative analysis yielded unique profiles for MAs, enabling the reliable identification of mycobacterial species. In a case-control study of tuberculosis (TB) and non-TB Polish patients, we demonstrated the potential diagnostic utility of our approach for the rapid diagnosis of active TB with sensitivity and specificity surpassing those of existing methods. This robust method allows the identification of TB-positive patients after 2 h of sample preparation in the case of direct sputum analysis or 10 days of culturing, both of which are followed by 1 min of liquid chromatography-tandem mass spectrometry analysis. PMID:23669043

Szewczyk, Rafa?; Kowalski, Konrad; Janiszewska-Drobinska, Beata; Druszczy?ska, Magdalena



Cyclotron production of 67Ga(III) with a tandem natGe-natZn target.  


Production of 67Ga(III) at the National Accelerator Centre is by proton bombardment of a natZn target, and uses 15-20 h of cyclotron beam time per production. A study was undertaken to use a tandem natGe-natZn target to produce the same amount of 67Ga, but using less beam time (7-8 h). 67Ga(III) was separated from the tandem target material by a method based on acid dissolution of the target and chromatography on an organic polymer resin (Amberchrom CG-71cd) containing no ion exchange groups. The separated 67Ga(III) has high radionuclidic purity and complies with the British and US Pharmacopoeia requirements for chemical purity. PMID:11300404

Naidoo, C; van der Walt, T N



Individual identification of cats and dogs using mitochondrial DNA tandem repeats?  


Cats and dogs are very common animals in the human environment. In Switzerland, one in five households owns a cat or a dog. Their hairs are very easily transferred and could be used as a frequent trace evidence. Using DNA analysis, identification of these animals should be possible as it is in human identification. However, most of the time, no nuclear DNA can be recovered from the hair. It is therefore necessary to rely on mtDNA. Cats and dogs have tandemly repeated sequences in their mtDNA control region. In this study, the authors show that these tandem repeats are very polymorphic but are also the source of a very high level of heteroplasmy. The authors, therefore, examined if this might prevent their use in forensic identification. PMID:10795405

Fridez, F; Rochat, S; Coquoz, R



Investigations on a radial compressor tandem-rotor stage with adjustable geometry  

NASA Astrophysics Data System (ADS)

A radial compressor stage has been investigated experimentally for aerodynamic stage optimization. The rotor consists of a profiled axial inducer and a conventionally designed radial impeller. Inducer and impeller can be locked at different circumferential positions relative to each other thus, forming a tandem wheel with adjustable geometry. Conventional and laser-2-focus system measurements for the tandem-rotor and the stage were performed at different operating points to study the influence of the circumferential clearance geometry between inducer and impeller with respect to compressor characteristics and performance. Furthermore, 3D Navier-Stokes calculations are being developed at design point condition to analyze the flow field. Small influence of the inducer adjustment on the rotor characteristics is observed. The maximum rotor efficiency of 93.5 percent varies in a range of less than 1 percent depending on the different inducer positions.

Josuhn-Kadner, B.; Hoffmann, B.



Inducibility of the HS II enhancer depends on binding of an erythroid specific nuclear protein.  

PubMed Central

An erythroid specific, inducible enhancer associated with hypersensitive site II (HS II) plays a central role in the function of the human beta globin dominant control region. The HS II enhancer consists of tandem AP-1 binding sites and has been shown to bind members of the ubiquitous jun and fos families of proteins. The same sites are now shown to bind the erythroid specific protein, NF-E2. Inducibility of the HS II enhancer depends on NF-E2 binding, even in the presence of another hypersensitive site. Further, increased activity of the enhancer in induced K562 cells correlates with the presence of NF-E2, which appears to be present in a modified form. NF-E2 is distinct from some enhancer binding proteins in K562 nuclear extracts, in that it does not contain Fos or Fra-1 protein. Thus, binding by NF-E2 may be the mechanism, whereby tandem AP-1 binding sites confer erythroid specificity on the HS II enhancer. Images PMID:2235483

Ney, P A; Sorrentino, B P; Lowrey, C H; Nienhuis, A W



Development of a negative hydrogen ion source for tandem proton accelerator using transformer couled plasma sources  

Microsoft Academic Search

A negative hydrogen ion source based on the transformer coupled plasma (TCP) source has been developed for 1.75 MeV tandem proton accelerator to detect underground explosives and mines. The TCP-based ion source has been designed and constructed for H- beam currents of 10 mA at the extraction voltage of 30 kV. High-density hydrogen plasmas of 1012 cm-3 are generated by

I. S. Hong; Y. S. Hwang; Y. S. Cho



Development of a negative hydrogen ion source for tandem proton accelerator using transformer couled plasma sources  

Microsoft Academic Search

A negative hydrogen ion source based on the transformer coupled plasma (TCP) source has been developed for 1.75 MeV tandem proton accelerator to detect underground explosives and mines. The TCP-based ion source has been designed and constructed for H? beam currents of 10 mA at the extraction voltage of 30 kV. High-density hydrogen plasmas of 1012 cm?3 are generated by

I. S. Hong; Y. S. Hwang; Y. S. Cho



Determination of 76 pharmaceutical drugs by liquid chromatography–tandem mass spectrometry in slaughterhouse wastewater  

Microsoft Academic Search

A multi-residue method for the analysis of 76 pharmaceutical agents of nine classes of drugs (tetracyclines, macrolides, fluoroquinolones, ?-agonists, ?-blockers, diuretics, sedatives, sulfonamides and chloramphenicol) in slaughterhouse wastewater and a receiving river is presented. After simultaneous extraction with an Oasis HLB solid-phase extraction (SPE) cartridge and further purification using an amino SPE cartridge, analytes were detected by liquid chromatography–electrospray ionization-tandem

Bing Shao; Dong Chen; Jing Zhang; Yongning Wu; Chengjun Sun



Ruthenium-catalyzed tandem-isomerization/asymmetric transfer hydrogenation of allylic alcohols.  


A one-pot procedure for the direct conversion of racemic allylic alcohols to enantiomerically enriched saturated alcohols is presented. The tandem-isomerization/asymmetric transfer hydrogenation process is efficiently catalyzed by [{Ru(p-cymene)Cl2 }2 ] in combination with the ?-amino acid hydroxyamide ligand 1, and performed under mild conditions in a mixture of ethanol and THF. The saturated alcohol products are isolated in good to excellent chemical yields and in enantiomeric excess up to 93?%. PMID:25339229

Slagbrand, Tove; Lundberg, Helena; Adolfsson, Hans



Drug Screening of Preserved Oral Fluid by Liquid Chromatography-Tandem Mass Spectrometry  

Microsoft Academic Search

Background: Oral fluid is an alternative matrix with potential applications in road-side drug screening, work-place testing, drug treatment programs, and epi- demiological surveys. Development of methods for ex- tensive drug screening in oral fluid is warranted. Methods: We developed a liquid chromatography- tandem mass spectrometry (LC-MS\\/MS) method for drug screening of preserved oral fluid collected with the Intercept® collection device.

Elisabeth Leere Øiestad; Unni Johansen; Asbjorg Solberg Christophersen


VIV of two cylinders in tandem arrangement: analytical and numerical modeling  

Microsoft Academic Search

Vortex-induced vibrations of two circular cylinders in tandem arrangement are studied both analytically and numerically. A low-order model for transverse vortex-induced vibrations of one degree-of- freedom elastically supported rigid cylinders is analyzed. The model, based on van der Pol oscillators, is first developed addressing the response of a single structure, and then extended to describe vortex- induced oscillations of two

M. L. Facchinetti; E. de Langre; E. Fontaine; P. A. Bonnet; S. Etienne; F. Biolley



Rapid and quantitative determination of solanesol in Nicotiana tabacum by liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

A rapid and sensitive liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) method with multiple reaction monitoring (MRM) was developed for the determination of solanesol in Nicotiana tabacum. Sample preparation was performed by ultrasonic extraction with methanol for 20min and then supernatant was extracted with hexane. The method used atmospheric pressure chemical ionization (APCI) detection in positive-ion mode. The separation of solanesol was

Chunjian Zhao; Chunying Li; Yuangang Zu



High energy collisions on tandem time-of-flight mass spectrometers†  

PubMed Central

Long before the introduction of matrix-assisted laser desorption (MALDI), electrospray ionization (ESI), Orbitraps and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were nonetheless some clear advantages for sectors over their low collision energy counterparts. Time-of-flight mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective we recount our own journey to produce high performance time-of-flights and tandems, describing the basic theory, problems and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging and the characterization of microorganisms. PMID:23519928

Cotter, Robert J.



Recent advances of liquid chromatography–(tandem) mass spectrometry in clinical and forensic toxicology  

Microsoft Academic Search

Liquid chromatography (LC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS\\/MS) has become increasingly important in clinical and forensic toxicology as well as doping control and is now a robust and reliable technique for routine analysis in these fields. In recent years, methods for LC–MS(\\/MS)-based systematic toxicological analysis using triple quadrupole or ion trap instruments have been considerably

Frank T. Peters



Improved screening capabilities in forensic toxicology by application of liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

The introduction of the upcoming instrumentation liquid chromatography–mass spectrometry (LC–MS) into the field of forensic toxicology was primarily focused on crucial substances, undetectable by current analytical techniques. Typically, polar substances (which cannot be derivatised properly) thermolabile and high molecular weight compounds were first targets of the analytical technique. Successful application of LC–tandem mass spectrometry (API 2000, Applied Biosystems) in multiple

Detlef Thieme; Hans Sachs



Numerical investigation of convective heat transfer in unsteady flow past two cylinders in tandem arrangements  

Microsoft Academic Search

Unsteady laminar convective heat transfer from two isothermal cylinders of tandem arrangement is numerically investigated. The numerical simulations were carried out by the commercial CFD software—FLUENT®. The working fluid is air. The analysis is carried out for the Reynolds numbers of 100 and 200 and for center-to-center distance ratio, L\\/D, of 2, 3, 4, 5, 7 and 10. The flow

Necati Mahír; Zekeriya Altaç



African Jordanian Population Genetic Database on Fifteen Short Tandem Repeat Genetic Loci  

Microsoft Academic Search

To establish a genetic database of the African-Jordanian population for forensic and paternity testing purposes. Method Allelic distribution at fifteen short tandem repeat (STR) loci was determined for 95 healthy unrelated Af- rican-Jordanians. The 15 autosomal STR loci, included within the GenePrint® PowerPlex™ 16 system, were amplified from the subset of the 95 DNA extracts isolated from the population sample.

Salem R. Yasin; Mawieh M. Hamad; Ali Z. ElKarmi; Adnan S. Jaran


Genetic individualization of Cannabis sativa by a short tandem repeat multiplex system  

Microsoft Academic Search

Cannabis sativa is the most frequently used of all illicit drugs in the USA. Cannabis has been used throughout history for its stems in the\\u000a production of hemp fiber, seed for oil and food, and buds and leaves as a psychoactive drug. Short tandem repeats (STRs) were\\u000a chosen as molecular markers owing to their distinct advantages over other genetic methods.

Maria A. Mendoza; DeEtta K. Mills; Hemant Lata; Suman Chandra; Mahmoud A. ElSohly; Jose R. Almirall



A simple tandem disk model for a cross-wind machine  

Microsoft Academic Search

The relative power coefficients, area expansion ratio, and crosswind forces for a crosswind tubine, e.g., the Darrieus, were examined with a tandem-disk, single-streamtube model. The upwind disk is assumed to be rectangular and the downwind disk is modeled as filling the wake of the upwind disk. Velocity and force triangles are devised for the factors operating at each blade. Attention

J. V. Healey



Compressible Flows in the Wakes of a Square Cylinder and Thick Symmetrical Airfoil Arranged in Tandem  

Microsoft Academic Search

Compressible flows in the wakes of a two-dimensional square cylinder (side length D = 20 mm) and thick symmetrical airfoil (NACA 0018, chord length 20 mm) arranged in tandem have been examined experimentally, at free-stream Mach numbers between 0.15 and 0.91, at freestream Reynolds numbers (based on the side length) between 7.0 x 10^4 and 4.2 x 10^5, and with

T. Nakagawa; G. E. A. Meier; R. Timm; H.-M. Lent



Organocatalytic enantioselective tandem aldol-cyclization reaction of ?-isothiocyanato imides and activated carbonyl compounds.  


The organocatalytic enantioselective tandem aldol-cyclization reactions of ?-isothiocyanato imides and activated carbonyl compounds, such as isatins, an ?-ketolactone and a 1,2-dione, have been studied with cinchona alkaloid-derived thiourea-catalysts. This methodology provided an easy way to access enantiomerically enriched spirobicyclic thiocarbamates with high yields and good to excellent stereoselectivity, which have been demonstrated to be useful precursors for the synthesis of biologically active molecules. PMID:21921975

Guang, Jie; Zhao, Cong-Gui



Seventeen Y-chromosomal short tandem repeat haplotypes in seven groups of population living in Taiwan  

Microsoft Academic Search

The analysis of Y-chromosome short tandem repeat (Y-STR) loci is a powerful tool in forensic casework. The aim of this study\\u000a was to present the 17 Y-STR loci haplotype distributions of groups of population living in Taiwan and to demonstrate genetic\\u000a distances between the groups as well as multidimensional scaling plot based on Y-STR genotype data. Five hundred and fifteen

Hsiao-Lin Hwa; Li-Hui Tseng; Tsang-Ming Ko; Yih-Yuan Chang; Hsiang-Yi Yin; Yi-Ning Su; James Chun-I Lee



FLT3 internal tandem duplication mutations induce myeloproliferative or lymphoid disease in a transgenic mouse model  

Microsoft Academic Search

Activating FMS-like tyrosine kinase 3 (FLT3) mutations have been identified in ?30% of patients with acute myelogenous leukemia (AML), and recently in a smaller subset of patients with acute lymphoblastic leukemia (ALL). To explore the in vivo consequences of an activating FLT3 internal tandem duplication mutation (FLT3-ITD), we created a transgenic mouse model in which FLT3-ITD was expressed under the

Benjamin H Lee; Ifor R Williams; Ema Anastasiadou; Christina L Boulton; Sarah W Joseph; Sonia M Amaral; David P Curley; Nicole Duclos; Brian J P Huntly; Doriano Fabbro; James D Griffin; Dwight Gary Gilliland



Better detection of FLT3 internal tandem duplication using peripheral blood plasma DNA  

Microsoft Academic Search

Somatic mutation of the FLT3 gene as an internal tandem duplication (ITD) of the juxtamembrane domain-coding sequence causes constitutive tyrosine phosphorylation and activation. Tumor-specific DNA has been documented in the sera of patients with solid tumors even when it is in an early stage. We compared the detection of FLT3 ITD in DNA extracted from cells of bone marrow (BM)

I Jilani; E Estey; T Manshuri; M Caligiuri; M Keating; F Giles; D Thomas; H Kantarjian; M Albitar



Analysis of FLT3 internal tandem duplication and D835 mutations in Chinese acute leukemia patients  

Microsoft Academic Search

Genomic aberrations of Fms-like tyrosine kinase 3 (FLT3), including internal tandem duplication (ITD) and point mutations, have been demonstrated in 25–30% of adults acute myeloid leukemia (AML) and are markers of poor prognosis. FLT3\\/ITD and D835 mutations were analyzed in 194 Chinese patients with acute leukemia and myelodysplastic syndromes (MDS) by polymerase chain reaction (PCR). FLT3\\/ITDs and D835 mutations were

Lihong Wang; Dong Lin; Xinwei Zhang; Sen Chen; Min Wang; Jianxiang Wang



Size of FLT3 internal tandem duplication has prognostic significance in patients with acute myeloid leukemia  

Microsoft Academic Search

FLT3 internal tandem duplications (FLT3\\/ ITDs) in the juxtamembrane domain are found in approximately 25% of acute my- eloid leukemia (AML) patients, ranging in size from 3 to hundreds of nucleotides. We examined whether the sizes of FLT3\\/ ITDs were associated with clinical out- comes in 151 AML patients enrolled in Southwest Oncology Group studies: S9333 and S9500. FLT3\\/ITDs were

Derek L. Stirewalt; Kenneth J. Kopecky; Soheil Meshinchi; Julia H. Engel; Era L. Pogosova-Agadjanyan; Jeremy Linsley; Marilyn L. Slovak; Cheryl L. Willman; Jerald P. Radich; Cell Biology



Internal tandem duplication of FLT3 associated with leukocytosis in acute promyelocytic leukemia  

Microsoft Academic Search

FLT3 is a member of receptor tyrosine kinases expressed in leukemia cells, as well as in hematopoietic stem cells. Recently, a somatic alteration of the FLT3 gene was found in acute myeloid leukemia, as an internal tandem duplication (FLT3\\/ITD) which caused elongation of the juxtamembrane (JM) domain of FLT3. Here we characterized the FLT3\\/ITD and investigated its clinical significance in

H Kiyoi; T Naoe; S Yokota; M Nakao; S Minami; K Kuriyama; A Takeshita; K Saito; S Hasegawa; S Shimodaira; J Tamura; C Shimazaki; K Matsue; H Kobayashi; N Arima; R Suzuki; H Morishita; H Saito; R Ueda; R Ohno



Half-life of Si-32 from tandem-accelerator mass spectrometry  

NASA Technical Reports Server (NTRS)

A newly developed mass-spectrometry technique employing a tandem Van de Graaff accelerator together with a special beam-transport system and heavy-ion detector has been used to determine the half-life of Si-32. The result obtained, 108 plus or minus 18 yr, disagrees with the accepted value of 330 plus or minus 40 yr. The implications of the new half-life of Si-32, which is used for dating studies, are discussed.

Elmore, D.; Anantaraman, N.; Fulbright, H. W.; Gove, H. E.; Nishiizumi, K.; Murrell, M. T.; Honda, M.; Hans, H. S.



Enrichment of Integral Membrane Proteins for Proteomic Analysis Using Liquid Chromatography-Tandem Mass Spectrometry  

Microsoft Academic Search

Currently, most proteomic studies rely on liquid chromatography-tandem mass spectrometry (LC-MS\\/MS) to detect and identify constituent peptides of enzymatically digested proteins obtained from various organisms and cell types. However, sample preparation methods for isolating membrane proteins typically involve the use of detergents, chaotropes, or reducing reagents that often interfere with electrospray ionization (ESI). To increase the identification of integral membrane

Josip Blonder; Michael B. Goshe; Ronald J. Moore; Liljiana Pasa-Tolic; Christophe D. Masselon; Mary S. Lipton; Richard D. Smith



Global Analysis of the Membrane Subproteome of Pseudomonas aeruginosa using Liquid Chromatography-Tandem Mass Spectrometry  

Microsoft Academic Search

Pseudomonas aeruginosa is one of the most significant opportunistic bacterial pathogens in humans causing infections and premature death in patients with cystic fibrosis, AIDS, severe burns, organ transplants or cancer. Liquid chromatography coupled online with tandem mass spectrometry (LC-MS\\/MS) was used for the large-scale proteomic analysis of the P. aeruginosa membrane subproteome. Concomitantly, an affinity labeling technique, using iodoacetyl-PEO biotin

Josip Blonder; Michael B. Goshe; Wenzhong Xiao; David G. Camp; Mark A. Wingerd; Ronald W. Davis; Richard D. Smith



Ra: A high efficiency, D-/sup 3/He, tandem mirror fusion reactor: Appendix C  

SciTech Connect

The Ra tandem mirror fusion reactor concept features inherent safety, high net plant efficiency, low cost of electricity, low radioactive waste generation, low activation, highly efficient direct conversion, thin radiation shields, and axisymmetric magnets. The safety and environmental features are achieved through the use of D/He-3 fuel, while the high efficiency derives from a new operating mode. ICRF stabilization allows an axisymmetric magnet set. 11 refs., 5 figs., 3 tabs.

Santarius, J.F.; Attaya, H.; Corradini, M.L.; El-Guebaly, L.A.; Emmert, G.A.; Kulcinski, G.L.; Larsen, E.M.; Maynard, C.W.; Musicki, Z.; Sawan, M.E.



Differentiation of bovine Staphylococcus aureus isolates by use of polymorphic tandem repeat typing  

Microsoft Academic Search

Staphylococcus aureus is a common cause of bovine mastitis. A simple and efficient typing method would be helpful in understanding S. aureus sources and spread. Ninety-six S. aureus strains, isolated between 1961 and 2003 from the milk of 90 dairy cows belonging to 75 French herds, were subjected to multiple-locus variable-number tandem repeats analysis (MLVA) by PCR. The conjunction of

Florence B. Gilbert; Angélina Fromageau; Ludovic Gélineau; Bernard Poutrel



Thermal denaturation of the BRCT tandem repeat region of human tumour suppressor gene product BRCA1  

Microsoft Academic Search

Reduced stability of the tandem BRCT domains of human BReast CAncer 1 (BRCA1) due to missense mutations may be critical for loss of function in DNA repair and damage-induced checkpoint control. In the present thermal denaturation study of the BRCA1 BRCT region, high-precision differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy provide evidence for the existence of a denatured

Serapion Pyrpassopoulos; Angela Ladopoulou; Metaxia Vlassi; Yannis Papanikolau; Constantinos E. Vorgias; Drakoulis Yannoukakos; George Nounesis



Landscape of Standing Variation for Tandem Duplications in Drosophila yakuba and Drosophila simulans  

PubMed Central

We have used whole genome paired-end Illumina sequence data to identify tandem duplications in 20 isofemale lines of Drosophila yakuba and 20 isofemale lines of D. simulans and performed genome wide validation with PacBio long molecule sequencing. We identify 1,415 tandem duplications that are segregating in D. yakuba as well as 975 duplications in D. simulans, indicating greater variation in D. yakuba. Additionally, we observe high rates of secondary deletions at duplicated sites, with 8% of duplicated sites in D. simulans and 17% of sites in D. yakuba modified with deletions. These secondary deletions are consistent with the action of the large loop mismatch repair system acting to remove polymorphic tandem duplication, resulting in rapid dynamics of gain and loss in duplicated alleles and a richer substrate of genetic novelty than has been previously reported. Most duplications are present in only single strains, suggesting that deleterious impacts are common. Drosophila simulans shows larger numbers of whole gene duplications in comparison to larger proportions of gene fragments in D. yakuba. Drosophila simulans displays an excess of high-frequency variants on the X chromosome, consistent with adaptive evolution through duplications on the D. simulans X or demographic forces driving duplicates to high frequency. We identify 78 chimeric genes in D. yakuba and 38 chimeric genes in D. simulans, as well as 143 cases of recruited noncoding sequence in D. yakuba and 96 in D. simulans, in agreement with rates of chimeric gene origination in D. melanogaster. Together, these results suggest that tandem duplications often result in complex variation beyond whole gene duplications that offers a rich substrate of standing variation that is likely to contribute both to detrimental phenotypes and disease, as well as to adaptive evolutionary change. PMID:24710518

Rogers, Rebekah L.; Cridland, Julie M.; Shao, Ling; Hu, Tina T.; Andolfatto, Peter; Thornton, Kevin R.



Population Genetics of Y-Chromosome Short Tandem Repeats in Humans  

Microsoft Academic Search

.   Eight human short tandem repeat polymorphisms (STRs) also known as microsatellites—DYS19, DYS388, DYS390, DYS391, DYS392,\\u000a DYS393, DYS389I, and DYS389II, mapping in the Y chromosome—were analyzed in two Iberian samples (Basques and Catalans). Allele\\u000a frequency distributions showed significant differences only for DYS392. Fst and gene diversity index (D) were estimated for the Y STRs. The values obtained are comparable to

Anna Pérez-Lezaun; Francesc Calafell; Mark Seielstad; Eva Mateu; David Comas; Elena Bosch; Jaume Bertranpetit



Performance predictions for monolithic, thin-film CdTe/Ge tandem solar cells  

E-print Network

of CdTe thin-film cells, their efficiency has not improved beyond the value of 16.5% reported in 20043 material, and the junction between the CdTe and Ge, must have in order for the proven efficiency of standPerformance predictions for monolithic, thin-film CdTe/Ge tandem solar cells D.L. Pulfrey*, J. Dell

Pulfrey, David L.


Simple broadband anti-reflective coatings for superstrate-type silicon-based tandem cells  

Microsoft Academic Search

In this paper, the superstrate-type silicon-based tandem cells between air and glass are added to a porous SiO2\\/MgF2 double-layer anti-reflective (DLAR) thin film structure in order to improve the glass substrate low reflectivity in a wide spectral range (400–1200nm), without high reflectivity in the near-infrared region. Practical discussion is presented, as well as experimental results of fabricated films and devices.

Ting-Wei Kuo; Ping-Kuan Chang; Yu-Shuang Yang; Mau-Phon Houng; Na-Fu Wang; Yu-Zen Tsai



The human telomerase gene: complete genomic sequence and analysis of tandem repeat polymorphisms in intronic regions  

Microsoft Academic Search

In this work, the full-length hTERT gene was isolated and the sequence of the previously unknown region in intron 6 as well as that of upstream and downstream hTERT regions was determined. We have shown that intron 6 includes a variable number of tandem repeats (VNTR) of a 38 bp sequence, (hTERT-VNTR 6-1). Eight alleles of hTERT-VNTR 6-1 were identified

Sun-Hee Leem; J Arturo Londoño-Vallejo; Jung-Hyun Kim; Hung Bui; Emmanuel Tubacher; Greg Solomon; Jung-Eun Park; Izumi Horikawa; Natalay Kouprina; J Carl Barrett; Vladimir Larionov



Identification of alternative splice variants in Aspergillus flavus through comparison of multiple tandem MS search algorithms  

Microsoft Academic Search

Background  Database searching is the most frequently used approach for automated peptide assignment and protein inference of tandem mass\\u000a spectra. The results, however, depend on the sequences in target databases and on search algorithms. Recently by using an\\u000a alternative splicing database, we identified more proteins than with the annotated proteins in Aspergillus flavus. In this study, we aimed at finding a

Kung-Yen Chang; David C Muddiman



Doping control analysis of trenbolone and related compounds using liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

Trenbolone (17?-hydroxy-estra-4,9,11-trien-3-one) and its derivatives such as 17?-methyltrenbolone represent a class of highly potent anabolic–androgenic steroids, which are prohibited in sports according to the regulation of the World Anti-Doping Agency (WADA). Due to marginal gas chromatographic properties of these compounds but excellent proton affinities resulting from a large and conjugated ?-electron system, liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) has been the

Mario Thevis; Sven Guddat; Wilhelm Schänzer



Determination of organic acids in fruits and vegetables by liquid chromatography with tandem-mass spectrometry  

Microsoft Academic Search

A method using liquid chromatography coupled to tandem-mass spectrometry (LC–MS\\/MS) with triple quadrupole in selective reaction monitoring mode was developed to determine organic acids (glutamic, tartaric, quinic, malonic, malic, shikimic, ?-ketoglutaric, pyruvic, citric, succinic and fumaric acids) in fruits (melon, grape, peach, orange, lemon) and vegetables (green and red pepper, tomato, lettuce and lamb’s lettuce). The negative ion mode of

Pilar Flores; Pilar Hellín; José Fenoll


Half-life of Si-32 from tandem-accelerator mass spectrometry  

NASA Astrophysics Data System (ADS)

A newly developed mass-spectrometry technique employing a tandem Van de Graaff accelerator together with a special beam-transport system and heavy-ion detector has been used to determine the half-life of Si-32. The result obtained, 108 plus or minus 18 yr, disagrees with the accepted value of 330 plus or minus 40 yr. The implications of the new half-life of Si-32, which is used for dating studies, are discussed.

Elmore, D.; Anantaraman, N.; Fulbright, H. W.; Gove, H. E.; Nishiizumi, K.; Murrell, M. T.; Honda, M.; Hans, H. S.



Gold(I)-Catalyzed Diazo Coupling: Strategy towards Alkene Formation and Tandem Benzannulation.  


A gold(I)-catalyzed cross-coupling of diazo compounds to afford tetrasubstituted alkenes has been developed by taking advantage of a trivial electronic difference between two diazo substrates. A N-heterocyclic-carbene-derived gold complex is the most effective catalyst for this transformation. Based on this new strategy, a gold(I)-initiated benzannulation has been achieved through a tandem reaction involving a diazo cross-coupling, 6??electrocyclization, and oxidative aromatization. PMID:25156018

Zhang, Daming; Xu, Guangyang; Ding, Dong; Zhu, Chenghao; Li, Jian; Sun, Jiangtao



Recent ¹⁴C measurements with the Chalk River tandem accelerator  

Microsoft Academic Search

The Chalk River Tandem Accelerator Mass Spectrometry System has reached a state of reliable measurement of ¹⁴C using 2 to 5mg elemental carbon prepared by Mg reduction of COâ. For two comparisons of a near-modern unknown with the NBS oxalic acid standard obtained a total error of approx.+\\/-4.5%, consisting of a random system error of about +\\/-3.5% combined with the

R. M. Brown; H. R. Andrews; G. C. Ball; N. Burn; W. G. Davies; Y. Imahori; J. C. D. Milton; W. Workamn



Quantitation of iptakalim in human plasma by high-performance liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

This paper describes a rapid and sensitive analytical method for the quantitation of iptakalim, a novel antihypertensive drug, in human plasma. The method is based on liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) using sildenafil as internal standard. Sample preparation involved liquid–liquid extraction with dichloromethane–diethyl ether (2:3, v\\/v) in a basic environment. Chromatography was carried out on an amino column with a

Guosheng Teng; Yingwu Wang; Yunbiao Tang; Rui Wang; Yi Fang; J. Paul Fawcett; Jingkai Gu



Liquid chromatography tandem mass spectrometry assay to determine the pharmacokinetics of aildenafil in human plasma  

Microsoft Academic Search

A simple, sensitive and specific liquid chromatography\\/tandem mass spectrometry method for the quantitation of aildenafil, a new phosphodiesterase V inhibitor, in human plasma is presented. The analyte and internal standard, sildenafil, were extracted by a one-step liquid–liquid extraction in alkaline conditions and separated on a C18 colunm using ammonia:10mM ammonium acetate buffer:methanol (0.1:15:85, v\\/v\\/v) as the mobile phase. The detection

Jiang Wang; Yao Jiang; Yingwu Wang; Xia Zhao; Yimin Cui; Jingkai Gu



Quantitation of tadalafil in human plasma by liquid chromatography–tandem mass spectrometry with electrospray ionization  

Microsoft Academic Search

A simple, rapid, sensitive and specific liquid chromatography–tandem mass spectrometry method was developed and validated for quantitation of tadalafil (I) in human plasma, a new selective, reversible phosphodiesterase 5 inhibitor. The analyte and internal standard (sildenafil, II) were extracted by liquid–liquid extraction with diethyl ether\\/dichloromethane (70\\/30, v\\/v) using a Glas-Col Multi-Pulse Vortexer. The chromatographic separation was performed on reverse phase

N. V. S. Ramakrishna; K. N. Vishwottam; S. Puran; M. Koteshwara; S. Manoj; M. Santosh; J. Chidambara; S. Wishu; B. Sumatha



Multilocus Variable-Number Tandem-Repeat Analysis for Investigation of Clostridium difficile Transmission in Hospitals  

Microsoft Academic Search

Clostridium difficile is a major cause of antibiotic-associated gastrointestinal illness. Recently, an increased incidence of hospital-acquired infections with severe outcomes has been reported in North America and Europe. Current molecular-typing methods for detection of outbreaks and nosocomial transmission are labor-intensive, subjective, or insufficiently discriminatory to differentiate between closely related strains. This report describes the development of multilocus variable-number tandem-repeat (VNTR)

Jane W. Marsh; Mary M. O'Leary; Kathleen A. Shutt; A. William Pasculle; Stuart Johnson; Dale N. Gerding; Carlene A. Muto; Lee H. Harrison



Solution processed, white emitting tandem organic light-emitting diodes with inverted device architecture.  


Fully solution processed monochromatic and white-light emitting tandem or multi-photon polymer OLEDs with an inverted device architecture have been realized by employing WO3 /PEDOT:PSS/ZnO/PEI charge carrier generation layers. The luminance of the sub-OLEDs adds up in the stacked device indicating multi-photon emission. The white OLEDs exhibit a CRI of 75. PMID:24899163

Höfle, Stefan; Schienle, Alexander; Bernhard, Christoph; Bruns, Michael; Lemmer, Uli; Colsmann, Alexander



Materials considerations for the coupling of thermochemical hydrogen cycles to tandem mirror reactors  

SciTech Connect

Candidate materials are discussed and initial choices made for the critical elements in a liquid Li-Na Cauldron Tandem Mirror blanket and the General Atomic Sulfur-Iodine Cycle for thermochemical hydrogen production. V and Ti alloys provide low neutron activation, good radiation damage resistance, and good chemical compatibility for the Cauldron design. Aluminide coated In-800H and siliconized SiC are materials choices for heat exchanger components in the thermochemical cycle interface.

Krikorian, O.H.



High-efficiency, monolithic, multi-bandgap, tandem photovoltaic energy converters  


A monolithic, multi-bandgap, tandem solar photovoltaic converter has at least one, and preferably at least two, subcells grown lattice-matched on a substrate with a bandgap in medium to high energy portions of the solar spectrum and at least one subcell grown lattice-mismatched to the substrate with a bandgap in the low energy portion of the solar spectrum, for example, about 1 eV.

Wanlass, Mark W. (Golden, CO)



Analysis of acrylamide in coffee and cocoa by isotope dilution liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

An accurate and precise method for the quantification of acrylamide using stable isotope dilution liquid chromatography–tandem\\u000a mass spectrometry was developed and used to measure acrylamide in coffee and cocoa samples. The sample preparation involved\\u000a extraction of the analyte and its internal standard, 13C3-acrylamide, into water and subsequent defatting of the aqueous extract with dichloromethane. An aliquot of the resulting\\u000a aqueous

Patricia C. Aguas; Matthew J. Fitzhenry; Georgina Giannikopoulos; Peter Varelis



Synfuels from fusion: using the tandem mirror reactor and a thermochemical cycle to produce hydrogen  

SciTech Connect

This study is concerned with the following area: (1) the tandem mirror reactor and its physics; (2) energy balance; (3) the lithium oxide canister blanket system; (4) high-temperature blanket; (5) energy transport system-reactor to process; (6) thermochemical hydrogen processes; (7) interfacing the GA cycle; (8) matching power and temperature demands; (9) preliminary cost estimates; (10) synfuels beyond hydrogen; and (11) thermodynamics of the H/sub 2/SO/sub 4/-H/sub 2/O system. (MOW)

Werner, R.W. (ed.)



Liquid chromatography–tandem mass spectrometry analysis of nitazoxanide and its major metabolites in goat  

Microsoft Academic Search

A rapid, sensitive and specific liquid chromatography–electrospray ionization (ESI) tandem mass spectrometry (LC–MS–MS) method has been developed for the identification of nitazoxanide metabolites in goat plasma and urine. The purified samples was separated using an XTerra MS C8 column with the mobile phase consisted of acetonitrile and 10-mM ammonium acetate buffer (pH 2.5) followed a linear gradient elution, and detected

Zhanzhong Zhao; Lifang Zhang; Feiqun Xue; Xiaoyang Wang; Wenli Zheng; Tao Zhang; Chenzhong Fei; Keyu Zhang; Minqi Qiu; Ruixiang Xin; Fengkun Yang



Ouricuri ( Syagrus coronata ) triacylglycerol analysis using HPLC and positive ion electrospray tandem MS  

Microsoft Academic Search

Among tropical oil sources in Brazil, the ouricuri (Syagrus coronata) tree is nearly ubiquitous. The exact TAG composition of oil from ouricuri fruits was elucidated with electrospray ionization\\/tandem\\u000a MS. The oil contains the following FA: caprylic (Cy), capric (Ca), lauric (La), myristic (M), palmitic, stearic, oleic, and\\u000a linoleic. An estimate of the relative TAG composition based on the neak areas

S. D. Segall; W. E. Artz; D. S. Raslan; V. P. Ferraz; J. A. Takahashi



Monolithic InP/Ga0.47In0.53As tandem solar cells for space  

NASA Technical Reports Server (NTRS)

A review is provided of progress made in the development of InP/Ga(0.47)In(0.53)As monolithic tandem solar cells since the last SPRAT conference. Improved one-sun, three terminal tandem designs have resulted in Air Mass Zero (AM0) efficiencies as high as 23.9 pct. at 25 C. Additionally, high efficiency concentrator versions of the three terminal device were developed. The best concentrator tandem has a peak AM0 efficiency of 28.8 pct. under 40.3 suns at 25 C. For the concentrator tandems, the subcell performance parameter temperature coefficients are reported as a function of the concentration ratio. Results from a computer modeling study are presented which provide a clear direction for improving the efficiency of the concentrator tandem. The prospects for fabricating high efficiency, series connected (i.e., two terminal) InP/Ga(0.47)In(0.53)As monolithic tandem cells are also discussed.

Wanlass, M. W.; Ward, J. S.; Coutts, T. J.; Emery, K. A.; Gessert, T. A.; Osterwald, C. R.



Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors, part 8  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted with an 0.8 hub/tip ratio, single-stage, axial flow compressor to determine the potential of tandem-airfoil blading for improving the efficiency and stable operating range of compressor stages. The investigation included testing of a baseline stage with single-airfoil blading and two tandem-blade stages. The overall performance of the baseline stage and the tandem-blade stage with a 20-80% loading split was considerably below the design prediction. The other tandem-blade stage, which had a rotor with a 50-50% loading split, came within 4.5% of the design pressure rise (delta P(bar)/P(bar) sub 1) and matched the design stage efficiency. The baseline stage with single-airfoil blading, which was designed to account for the actual rotor inlet velocity profile and the effects of axial velocity ratio and secondary flow, achieved the design predicted performance. The corresponding tandem-blade stage (50-50% loading split in both blade rows) slightly exceeded the design pressure rise but was 1.5 percentage points low in efficiency. The tandem rotors tested during both phases demonstrated higher pressure rise and efficiency than the corresponding single-airfoil rotor, with identical inlet and exit airfoil angles.

Brent, J. A.; Clemmons, D. R.



Application of Tandem System to high-efficiency refrigerator/freezer  

SciTech Connect

The Tandem System, a new approach for using two evaporators in a refrigerator/freezer system, has been developed. The system configuration, with two evaporators connected in series and appropriate controls, takes advantage of the transient operation to save energy. This system was applied to a commercial 18 ft{sup 3} (509.7 L) unit and a high-efficiency sample unit in which the thick insulation and energy-saving valve were used. The daily energy consumptions for both units were reduced by 18% as compared to the baseline unit. In addition, a new defrost method without using an electrical resistance heater was introduced, and the test was performed experimentally. This internal defrost method, using the thermosiphon phenomenon between two evaporators, showed the potential of superior characteristics over the conventional approach. Taking advantage of control techniques, the Tandem System allowed independent temperature control for each compartment. Finally, a capability test showed that the Tandem System operated reliably at very different operating conditions.

Kim, K.; Radermacher, R. [Univ. of Maryland, College Park, MD (United States). Center for Environmental Energy Engineering; Kopko, B. [Environmental Protection Agency, Washington, DC (United States)



Flow-induced vibrations of two tandem circular cylinders in a parallel-wall channel  

NASA Astrophysics Data System (ADS)

Flow-induced vibrations of one and two tandem circular cylinders in the flow around cylinders in a parallel-wall channel are numerically studied by the lattice Boltzmann method. Within a range of Reynolds number Re = [1, 160], the effects of streamwise separation between two cylinders S/D = [1.25, 3], mass ratio M = [0.05, 5], and blockage ratio ? = [1/2, 1/8] on the motions of cylinders and fluids are investigated, respectively. For the case of an isolated cylinder, as the mass ratio is 1, no large-amplitude oscillation is observed, and as the mass ratio is 0.1, the cylinder motion translates from the steady regime to the biased periodic vibration with a large oscillation amplitude gradually as Reynolds number is increased from 1 to 160. For the case of two cylinders in tandem, two steady regimes and a variety of distinct oscillation regimes with the corresponding flow structures are observed. The critical mass ratio of the two tandem cylinders in the strong coupling regime is about an order of magnitude larger than that of an isolated cylinder. For blockage ratio is more than 1/5, the vibration type of the cylinders is exclusive, while for blockage ratio is less than 1/6, the cylinder oscillation state is bistable. The mechanisms of the observed phenomena are also discussed.

Jiang, Ren-Jie; Lin, Jian-Zhong; Ku, Xiao-Ke



X-ray scattering study of actin polymerization nuclei assembled by tandem W domains  

SciTech Connect

The initiation of actin polymerization in cells requires actin filament nucleators. With the exception of formins, known filament nucleators use the Wiskott-Aldrich syndrome protein (WASP) homology 2 (WH2 or W) domain for interaction with actin. A common architecture, found in Spire, Cobl, VopL, and VopF, consists of tandem W domains that tie together three to four actin monomers to form a polymerization nucleus. Uncontrollable polymerization has prevented the structural investigation of such nuclei. We have engineered stable nuclei consisting of an actin dimer and a trimer stabilized by tandem W domain hybrid constructs and studied their structures in solution by x-ray scattering. We show that Spire-like tandem W domains stabilize a polymerization nucleus by lining up actin subunits along the long-pitch helix of the actin filament. Intersubunit contacts in the polymerization nucleus, thought to involve the DNase I-binding loop of actin, coexist with the binding of the W domain in the cleft between actin subdomains 1 and 3. The successful stabilization of filament-like multiactin assemblies opens the way to the crystallographic investigation of intersubunit contacts in the actin filament.

Rebowski, Grzegorz; Boczkowska, Malgorzata; Hayes, David B.; Guo, Liang; Irving, Thomas C.; Dominguez, Roberto (IIT); (UPENN); (BBRI)



Evaluation of tandem repeats for MLVA typing of Streptococcus uberis isolated from bovine mastitis  

PubMed Central

Background Streptococcus uberis is a common cause of bovine mastitis and recommended control measures, based on improved milking practice, teat dipping and antibiotic treatment at drying-off, are poorly efficient against this environmental pathogen. A simple and efficient typing method would be helpful in identifying S.uberis sources, virulent strains and cow to cow transmission. The potential of MLVA (Multiple Loci VNTR Analysis; VNTR, Variable Number of Tandem Repeats) for S. uberis mastitis isolates genotyping was investigated. Results The genomic sequence of Streptococcus uberis (strain 0104J) was analyzed for potential variable number tandem repeats (VNTRs). Twenty-five tandem repeats were identified and amplified by PCR with DNA samples from 24 S. uberis strains. A set of seven TRs were found to be polymorphic and used for MLVA typing of 88 S. uberis isolates. A total of 82 MLVA types were obtained with 22 types among 26 strains isolated from the milk of mastitic cows belonging to our experimental herd, and 61 types for 62 epidemiologically unrelated strains, i.e. collected in different herds and areas. Conclusion The MLVA method can be applied to S. uberis genotyping and constitutes an interesting complement to existing typing methods. This method, which is easy to perform, low cost and can be used in routine, could facilitate investigations of the epidemiology of S. uberis mastitis in dairy cows. PMID:17112377

Gilbert, Florence B; Fromageau, Angelina; Lamoureux, Jeremy; Poutrel, Bernard



Tandem-L: Monitoring the Earth's Dynamics with InSAR and Pol-InSAR  

NASA Astrophysics Data System (ADS)

Tandem-L is a German mission proposal for an innovative interferometric L-band radar mission that enables the systematic monitoring of dynamic Earth processes using advanced techniques and technologies. The mission is science driven aiming to provide a unique data set for climate and environmental research, geodynamics, hydrology and oceanography. Important application examples are global forest height and biomass inventories, measurements of Earth deformation due to tectonic processes and/or anthropogenic factors, observations of ice/glacier velocity field and 3-D structure changes, and the monitoring of ocean surface currents. The Tandem-L mission concept consists of two cooperating satellites flying in close formation. The Pol-InSAR and repeat-pass acquisition modes provide a unique data source to observe, analyse and quantify a wide range of mutually interacting processes in the bio-, litho-, hydro- and cryosphere. The systematic observation of these processes benefits from the high data acquisition capacity and the novel high-resolution wide-swath SAR imaging modes that combine digital beamforming with a large reflector antenna. This paper provides an overview of the Tandem-L mission concept and its main application areas.

Moriera, A.; Hajnsek, I.; Krieger, G.; Papathanassiou, K.; Eineder, M.; De Zan, F.; Younis, M.; Werner, M.



A polymer tandem solar cell with 10.6% power conversion efficiency  

PubMed Central

An effective way to improve polymer solar cell efficiency is to use a tandem structure, as a broader part of the spectrum of solar radiation is used and the thermalization loss of photon energy is minimized. In the past, the lack of high-performance low-bandgap polymers was the major limiting factor for achieving high-performance tandem solar cell. Here we report the development of a high-performance low bandgap polymer (bandgap <1.4?eV), poly[2,7-(5,5-bis-(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2?,3?-d]pyran)-alt-4,7-(5,6-difluoro-2,1,3-benzothia diazole)] with a bandgap of 1.38?eV, high mobility, deep highest occupied molecular orbital. As a result, a single-junction device shows high external quantum efficiency of >60% and spectral response that extends to 900?nm, with a power conversion efficiency of 7.9%. The polymer enables a solution processed tandem solar cell with certified 10.6% power conversion efficiency under standard reporting conditions (25?°C, 1,000?Wm?2, IEC 60904-3 global), which is the first certified polymer solar cell efficiency over 10%. PMID:23385590

You, Jingbi; Dou, Letian; Yoshimura, Ken; Kato, Takehito; Ohya, Kenichiro; Moriarty, Tom; Emery, Keith; Chen, Chun-Chao; Gao, Jing; Li, Gang; Yang, Yang



Authentication of fish products by large-scale comparison of tandem mass spectra.  


Authentication of food is a major concern worldwide to ensure that food products are correctly labeled in terms of which animals are actually processed for consumption. Normally authentication is based on species recognition by comparison of selected sequences of DNA or protein. We here present a new robust, proteome-wide tandem mass spectrometry method for species recognition and food product authentication. The method does not use or require any genome sequences or selection of tandem mass spectra but uses all acquired data. The experimental steps were performed in a simple, standardized workflow including protein extraction, digestion, and data analysis. First, a set of reference spectral libraries was generated using unprocessed muscle tissue from 22 different fish species. Query tandem mass spectrometry data sets from "unknown" fresh muscle tissue samples were then searched against the reference libraries. The number of matching spectra could unambiguously identify the origin of all fresh samples. A number of processed samples were also analyzed to further test the robustness and applicability of the method. The results clearly show that the method is also able to correctly identify heavily processed samples. PMID:24032411

Wulff, Tune; Nielsen, Michael Engelbrecht; Deelder, André M; Jessen, Flemming; Palmblad, Magnus



Differentiation of bovine Staphylococcus aureus isolates by use of polymorphic tandem repeat typing.  


Staphylococcus aureus is a common cause of bovine mastitis. A simple and efficient typing method would be helpful in understanding S. aureus sources and spread. Ninety-six S. aureus strains, isolated between 1961 and 2003 from the milk of 90 dairy cows belonging to 75 French herds, were subjected to multiple-locus variable-number tandem repeats analysis (MLVA) by PCR. The conjunction of clfA, clfB, SAV1078 and fnb gene tandem repeats (TRs) enabled the definition of 61 types. When coa, spa, sdrC, sdrD and sspA TRs were used individually as additional markers, 63, 68, 67, 65 and 67 types were defined, respectively, versus 77 types when they were all included in the method. These additional TRs did not improve the differentiation of isolates collected in the same farm. The MLVA procedure using the tandem repeats embedded in clfA, clfB, SAV1078 and fnb loci as a basic combination at the herd level or associated with other TRs such as spa, sdrC, sdrD, sspA and coa can be a valuable tool for bovine S. aureus epidemiological studies. PMID:16814960

Gilbert, Florence B; Fromageau, Angélina; Gélineau, Ludovic; Poutrel, Bernard



Control of surface thermal scratch of strip in tandem cold rolling  

NASA Astrophysics Data System (ADS)

The thermal scratch seriously affects the surface quality of the cold rolled stainless steel strip. Some researchers have carried out qualitative and theoretical studies in this field. However, there is currently a lack of research on effective forecast and control of thermal scratch defects in practical production, especially in tandem cold rolling. In order to establish precise mathematical model of oil film thickness in deformation zone, the lubrication in cold rolling process of SUS410L stainless steel strip is studied, and major factors affecting oil film thickness are also analyzed. According to the principle of statistics, mathematical model of critical oil film thickness in deformation zone for thermal scratch is built, with fitting and regression analytical method, and then based on temperature comparison method, the criterion for deciding thermal scratch defects is put forward. Storing and calling data through SQL Server 2010, a software on thermal scratch defects control is developed through Microsoft Visual Studio 2008 by MFC technique for stainless steel in tandem cold rolling, and then it is put into practical production. Statistics indicate that the hit rate of thermal scratch is as high as 92.38%, and the occurrence rate of thermal scratch is decreased by 89.13%. Owing to the application of the software, the rolling speed is increased by approximately 9.3%. The software developed provides an effective solution to the problem of thermal scratch defects in tandem cold rolling, and helps to promote products surface quality of stainless steel strips in practical production.

Chen, Jinshan; Li, Changsheng



Development of Intelligent Wind Turbine Unit with Tandem Wind Rotors and Double Rotational Armatures  

NASA Astrophysics Data System (ADS)

The authors have invented the superior wind turbine unit which is composed of the tandem wind rotors and the double rotational armature type generator without the traditional stator. The large-sized front wind rotor and the small-sized rear wind rotor drive the inner and the outer armatures respectively, in keeping the rotational torque counter-balanced. Such operating conditions may be able to make the output higher than the traditional wind turbines, and to keep the output constant in the rated operation mode without the brakes and/or the pitch control mechanism. The unique rotational conditions of the tandem wind rotors and the fundamental characteristics of this unit were presented at the previous paper. Continuously, this paper discusses experimentally the effects of the tandem wind rotor profiles on the characteristics of this unit. The desirable profiles and the main results are as follows. (1) The optimum diameter ratio is DRF (rear wind rotor diameter divided by the front wind rotor diameter)=0.84, and the axial distance between both wind rotors should be set as short as possible. (2) The output is higher while the relative tip speed ratio increases as compared with the single wind rotor.

Kubo, Koichi; Kanemoto, Toshiaki


Tandem duplication of chromosomal segments is common in ovarian and breast cancer genomes  

PubMed Central

The application of paired-end next generation sequencing approaches has made it possible to systematically characterize rearrangements of the cancer genome to base-pair level. Utilizing this approach, we report the first detailed analysis of ovarian cancer rearrangements, comparing high-grade serous and clear cell cancers, and these histotypes with other solid cancers. Somatic rearrangements were systematically characterized in eight high-grade serous and five clear cell ovarian cancer genomes and we report here the identification of > 600 somatic rearrangements. Recurrent rearrangements of the transcriptional regulator gene, TSHZ3, were found in three of eight serous cases. Comparison to breast, pancreatic and prostate cancer genomes revealed that a subset of ovarian cancers share a marked tandem duplication phenotype with triple-negative breast cancers. The tandem duplication phenotype was not linked to BRCA1/2 mutation, suggesting that other common mechanisms or carcinogenic exposures are operative. High-grade serous cancers arising in women with germline BRCA1 or BRCA2 mutation showed a high frequency of small chromosomal deletions. These findings indicate that BRCA1/2 germline mutation may contribute to widespread structural change and that other undefined mechanism(s), which are potentially shared with triple-negative breast cancer, promote tandem chromosomal duplications that sculpt the ovarian cancer genome. Copyright © 2012 Pathological Society of Great Britain and Ireland. PMID:22514011

McBride, David J; Etemadmoghadam, Dariush; Cooke, Susanna L; Alsop, Kathryn; George, Joshy; Butler, Adam; Cho, Juok; Galappaththige, Danushka; Greenman, Chris; Howarth, Karen D; Lau, King W; Ng, Charlotte K; Raine, Keiran; Teague, Jon; Wedge, David C; Cancer Study Group, Australian Ovarian; Caubit, Xavier; Stratton, Michael R; Brenton, James D; Campbell, Peter J; Futreal, P Andrew; Bowtell, David DL



Use of Short Tandem Repeat Sequences to Study Mycobacterium leprae in Leprosy Patients in Malawi and  

E-print Network

Background: Inadequate understanding of the transmission of Mycobacterium leprae makes it difficult to predict the impact of leprosy control interventions. Genotypic tests that allow tracking of individual bacterial strains would strengthen epidemiological studies and contribute to our understanding of the disease. Methodology/Principal Findings: Genotyping assays based on variation in the copy number of short tandem repeat sequences were applied to biopsies collected in population-based epidemiological studies of leprosy in northern Malawi, and from members of multi-case households in Hyderabad, India. In the Malawi series, considerable genotypic variability was observed between patients, and also within patients, when isolates were collected at different times or from different tissues. Less within-patient variability was observed when isolates were collected from similar tissues at the same time. Less genotypic variability was noted amongst the closely related Indian patients than in the Malawi series. Conclusions/Significance: Lineages of M. leprae undergo changes in their pattern of short tandem repeat sequences over time. Genetic divergence is particularly likely between bacilli inhabiting different (e.g., skin and nerve) tissues. Such variability makes short tandem repeat sequences unsuitable as a general tool for population-based strain typing of M. leprae, or for distinguishing relapse from reinfection. Careful use of these markers may provide insights into the

Saroj K. Young; Jorg M. Ponnighaus; Suman Jain; Sebastian Lucas; Sujai Suneetha; Diana N. J


Significant deviations in the configurations of homologous tandem repeats in prokaryotic genomes.  


We explored the possibilities of whole-genome duplication (WGD) in prokaryotic species, where we performed statistical analyses of the configurations of the central angles between homologous tandem repeats (TRs) on the circular chromosomes. At first, we detected TRs on their chromosomes and identified equivalent tandem repeat pairs (ETRPs); here, an ETRP is defined as a pair of tandem repeats sequentially similar to each other. Then we carried out statistical analyses of the central angle distributions of the detected ETRPs on each circular chromosome by way of comparisons between the detected distributions and those generated by null models. In the analyses, we estimated a P value by a simulation using the Kullback-Leibler divergence as a distance measure between two distributions. As a result, the central angle distributions for 8 out of the 203 prokaryotic species showed statistically significant deviations (P<0.05). In particular, we found out the characteristic feature of one round of WGD in Photorhabdus luminescens genome and that of two rounds of WGD in Escherichia coli K12. PMID:20172489