Organic electronic devices with multiple solution-processed layers

DOEpatents

Forrest, Stephen R.; Lassiter, Brian E.; Zimmerman, Jeramy D.

2015-08-04

A method of fabricating a tandem organic photosensitive device involves depositing a first layer of an organic electron donor type material film by solution-processing of the organic electron donor type material dissolved in a first solvent; depositing a first layer of an organic electron acceptor type material over the first layer of the organic electron donor type material film by a dry deposition process; depositing a conductive layer over the interim stack by a dry deposition process; depositing a second layer of the organic electron donor type material over the conductive layer by solution-processing of the organic electron donor type material dissolved in a second solvent, wherein the organic electron acceptor type material and the conductive layer are insoluble in the second solvent; depositing a second layer of an organic electron acceptor type material over the second layer of the organic electron donor type material film by a dry deposition process, resulting in a stack.

Hybrid/Tandem Laser-Arc Welding of Thick Low Carbon Martensitic Stainless Steel Plates =

NASA Astrophysics Data System (ADS)

Mirakhorli, Fatemeh

High efficiency and long-term life of hydraulic turbines and their assemblies are of utmost importance for the hydropower industry. Usually, hydroelectric turbine components are made of thick-walled low carbon martensitic stainless steels. The assembly of large hydroelectric turbine components has been a great challenge. The use of conventional welding processes involves typical large groove design and multi-pass welding to fill the groove which exposes the weld to a high heat input creating relatively large fusion zone and heat affected zone. The newly-developed hybrid/tandem laser-arc welding technique is believed to offer a highly competitive solution to improve the overall hydro-turbine performance by combining the high energy density and fast welding speed of the laser welding technology with the good gap bridging and feeding ability of the gas metal arc welding process to increase the productivity and reduce the consumable material. The main objective of this research work is to understand different challenges appearing during hybrid laser-arc welding (HLAW) of thick gauge assemblies of low carbon 13%Cr- 4%Ni martensitic stainless steel and find a practical solution by adapting and optimizing this relatively new welding process in order to reduce the number of welding passes necessary to fill the groove gap. The joint integrity was evaluated in terms of microstructure, defects and mechanical properties in both as-welded and post-welded conditions. A special focus was given to the hybrid and tandem laser-arc welding technique for the root pass. Based on the thickness of the low carbon martensitic stainless steel plates, this work is mainly focused on the following two tasks: • Single pass hybrid laser-arc welding of 10-mm thick low carbon martensitic stainless steel. • Multi-pass hybrid/tandem laser-arc welding of 25-mm thick martensitic stainless steel.

Progress in Tandem Solar Cells Based on Hybrid Organic-Inorganic Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Bo; Zheng, Xiaopeng; Bai, Yang

Owing to their high efficiency, low-cost solution-processability, and tunable bandgap, perovskite solar cells (PSCs) made of hybrid organic-inorganic perovskite (HOIP) thin films are promising top-cell candidates for integration with bottom-cells based on Si or other low-bandgap solar-cell materials to boost the power conversion efficiency (PCE) beyond the Shockley-Quiesser (S-Q) limit. In this review, recent progress in such tandem solar cells based on the emerging PSCs is summarized and reviewed critically. Notable achievements for different tandem solar cell configurations including mechanically-stacked, optical coupling, and monolithically-integrated with PSCs as top-cells are described in detail. Highly-efficient semitransparent PSC top-cells with high transmittance inmore » near-infrared (NIR) region are critical for tandem solar cells. Different types of transparent electrodes with high transmittance and low sheet-resistance for PSCs are reviewed, which presents a grand challenge for PSCs. The strategies to obtain wide-bandgap PSCs with good photo-stability are discussed. In conclusion, the PCE reduction due to reflection loss, parasitic absorption, electrical loss, and current mismatch are analyzed to provide better understanding of the performance of PSC-based tandem solar cells.« less

Progress in Tandem Solar Cells Based on Hybrid Organic-Inorganic Perovskites

DOE PAGES

Chen, Bo; Zheng, Xiaopeng; Bai, Yang; ...

2017-03-06

Owing to their high efficiency, low-cost solution-processability, and tunable bandgap, perovskite solar cells (PSCs) made of hybrid organic-inorganic perovskite (HOIP) thin films are promising top-cell candidates for integration with bottom-cells based on Si or other low-bandgap solar-cell materials to boost the power conversion efficiency (PCE) beyond the Shockley-Quiesser (S-Q) limit. In this review, recent progress in such tandem solar cells based on the emerging PSCs is summarized and reviewed critically. Notable achievements for different tandem solar cell configurations including mechanically-stacked, optical coupling, and monolithically-integrated with PSCs as top-cells are described in detail. Highly-efficient semitransparent PSC top-cells with high transmittance inmore » near-infrared (NIR) region are critical for tandem solar cells. Different types of transparent electrodes with high transmittance and low sheet-resistance for PSCs are reviewed, which presents a grand challenge for PSCs. The strategies to obtain wide-bandgap PSCs with good photo-stability are discussed. In conclusion, the PCE reduction due to reflection loss, parasitic absorption, electrical loss, and current mismatch are analyzed to provide better understanding of the performance of PSC-based tandem solar cells.« less

Characterization of solution-phase and gas-phase reactions in on-line electrochemistry-thermospray tandem mass spectrometry.

PubMed

Volk, K J; Yost, R A; Brajter-Toth, A

1989-07-14

Electrochemistry was used on-line with high-performance liquid chromatography-thermospray tandem mass spectrometry to provide insight into the solution-phase decomposition reactions of electrochemically generated oxidation products. Products formed during electrooxidation were monitored as the electrode potential was varied. The solution reactions which follow the initial electron transfer at the electrode are affected by the vaporizer tip temperature of the thermospray probe and the composition of the thermospray buffer. Either hydrolysis or ammonolysis reactions of the initial electrochemical oxidation products can occur with pH 7 ammonium acetate buffer. Both the electrochemically generated and the synthesized disulfide of 6-thiopurine decompose under thermospray conditions to produce 6-thiopurine and purine-6-sulfinate. Solution-phase studies indicate that nucleophilic and electrophilic substitution reactions with purine-6-sulfinate result in the formation of purine, adenine, and hypoxanthine. Products were identified and characterized by tandem mass spectrometry. This work shows the first example of high-performance liquid chromatography used on-line with electrochemistry to separate stable oxidation products prior to analysis by thermospray tandem mass spectrometry. In addition, solution-phase and gas-phase studies with methylamine show that the site of the nucleophilic and electrophilic reactions is probably inside the thermospray probe. Most importantly, these results also show that the on-line combination of electrochemistry with thermospray tandem mass spectrometry provides valuable information about redox and associated chemical reactions of biological molecules such as the structures of intermediates or products as well as providing insight into reaction pathways.

High work function transparent middle electrode for organic tandem solar cells

NASA Astrophysics Data System (ADS)

Moet, D. J. D.; de Bruyn, P.; Blom, P. W. M.

2010-04-01

The use of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) in combination with ZnO as middle electrode in solution-processed organic tandem solar cells requires a pH modification of the PEDOT:PSS dispersion. We demonstrate that this neutralization leads to a reduced work function of PEDOT:PSS, which does not affect the performance of polythiophene:fullerene solar cells, but results in a lower open-circuit voltage of devices based on a polyfluorene derivative with a higher ionization potential. The introduction of a thin layer of a perfluorinated ionomer recovers the anode work function and gives an open-circuit voltage of 1.92 V for a double junction polyfluorene-based solar cell.

Ultra-high-performance liquid chromatography/tandem high-resolution mass spectrometry analysis of sixteen red beverages containing carminic acid: identification of degradation products by using principal component analysis/discriminant analysis.

PubMed

Gosetti, Fabio; Chiuminatto, Ugo; Mazzucco, Eleonora; Mastroianni, Rita; Marengo, Emilio

2015-01-15

The study investigates the sunlight photodegradation process of carminic acid, a natural red colourant used in beverages. For this purpose, both carminic acid aqueous standard solutions and sixteen different commercial beverages, ten containing carminic acid and six containing E120 dye, were subjected to photoirradiation. The results show different patterns of degradation, not only between the standard solutions and the beverages, but also from beverage to beverage. Due to the different beverage recipes, unpredictable reactions take place between the dye and the other ingredients. To identify the dye degradation products in a very complex scenario, a methodology was used, based on the combined use of principal component analysis with discriminant analysis and ultra-high-performance liquid chromatography coupled with tandem high resolution mass spectrometry. The methodology is unaffected by beverage composition and allows the degradation products of carminic acid dye to be identified for each beverage. Copyright © 2014 Elsevier Ltd. All rights reserved.

1,5-(H, RO, RS) shift/6π-electrocyclic ring closure tandem processes on N-[(α-heterosubstituted)-2-tolyl]ketenimines: a case study of relative migratory aptitudes and activating effects.

PubMed

Alajarín, Mateo; Bonillo, Baltasar; Orenes, Raúl-Angel; Ortín, María-Mar; Vidal, Angel

2012-12-28

A number of N-aryl ketenimines, substituted at the ortho position either with different non-cyclic acetalic functions (acetals, monothioacetals, dithioacetals) or with only one alkoxymethyl or (alkylthio)methyl group, have been prepared and submitted to thermal treatment in toluene solution. Under smooth heating the ketenimines bearing non-cyclic acetals converted into 3,4-dihydroquinolines following two competitive tandem sequences that involve the alternative 1,5 migration of a hydride or alkoxy group as the first mechanistic step, followed by subsequent 6π electrocyclic ring closure. The heterocumulenes bearing acyclic monothioacetal and dithioacetal functions converted via a unique consecutive process involving the selective migration of the alkanethiolate group. Ketenimines bearing only one ether or thioether group transformed exclusively by the tandem sequence initiated by a 1,5 hydride shift. All these transformations provided as final reaction products a variety of quinoline derivatives with a range of substitution patterns. From these experiments the following order of propensity to migration can be extracted: RS > RO > H. It was also possible to estimate the following order of relative activating activities: RO > RS > H.

A polymer tandem solar cell with 10.6% power conversion efficiency.

PubMed

You, Jingbi; Dou, Letian; Yoshimura, Ken; Kato, Takehito; Ohya, Kenichiro; Moriarty, Tom; Emery, Keith; Chen, Chun-Chao; Gao, Jing; Li, Gang; Yang, Yang

2013-01-01

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%.

A polymer tandem solar cell with 10.6% power conversion efficiency

PubMed Central

You, Jingbi; Dou, Letian; Yoshimura, Ken; Kato, Takehito; Ohya, Kenichiro; Moriarty, Tom; Emery, Keith; Chen, Chun-Chao; Gao, Jing; Li, Gang; Yang, Yang

2013-01-01

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

A Hybrid Tandem Solar Cell Combining a Dye-Sensitized and a Polymer Solar Cell.

PubMed

Shao, Zhipeng; Chen, Shuanghong; Zhang, Xuhui; Zhu, Liangzheng; Ye, Jiajiu; Dai, Songyuan

2016-06-01

A hybrid tandem solar cell was assambled by connecting a dye sensitized solar cell and a polymer solar cell in series. A N719 sensitized TiO2 was used as photocathode in dye-sensitized subcell, and a MEH-PPV/PCBM composite was used as active layer in the polymer subcell. The polymer subcell fabricated on the counter electrode of the dye sensitized solar cell. A solution processed TiO(x) layer was used as electron collection layer of the polymer sub cell and the charge recombination layer. The effects of the TiO(x) interlayer and the spectral overlap between the two sub cells have been studied and optimized. The results shows that a proper thickness of the TiO(x) layer is needed for tandem solar cells. Thick TiO(x) will enhance the series resistance, but too thin TiO(x), layer will damage the hole blocking effect and its hydrophilic. The resulting optimized tandem solar cells exhibited a power conversion efficiency of 1.28% with a V(oc) of 0.95 V under simulated 100 mW cm(-2) AM 1.5 illumination.

Accurate determination of non-metallic impurities in high purity tetramethylammonium hydroxide using inductively coupled plasma tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Fu, Liang; Xie, Hualin; Shi, Shuyun; Chen, Xiaoqing

2018-06-01

The content of non-metallic impurities in high-purity tetramethylammonium hydroxide (HPTMAH) aqueous solution has an important influence on the yield, electrical properties and reliability of the integrated circuit during the process of chip etching and cleaning. Therefore, an efficient analytical method to directly quantify the content of non-metallic impurities in HPTMAH aqueous solutions is necessary. The present study was aimed to develop a novel method that can accurately determine seven non-metallic impurities (B, Si, P, S, Cl, As, and Se) in an aqueous solution of HPTMAH by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). The samples were measured using a direct injection method. In the MS/MS mode, oxygen and hydrogen were used as reaction gases in the octopole reaction system (ORS) to eliminate mass spectral interferences during the analytical process. The detection limits of B, Si, P, S, Cl, As, and Se were 0.31, 0.48, 0.051, 0.27, 3.10, 0.008, and 0.005 μg L-1, respectively. The samples were analyzed by the developed method and the sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) was used for contrastive analysis. The values of these seven elements measured using ICP-MS/MS were consistent with those measured by SF-ICP-MS. The proposed method can be utilized to analyze non-metallic impurities in HPTMAH aqueous solution. Table S2 Multiple potential interferences on the analytes. Table S3 Parameters of calibration curve and the detection limit (DL). Table S4 Results obtained for 25% concentration high-purity grade TMAH aqueous solution samples (μg L-1, mean ± standard deviation, n = 10).

Voice over internet protocol with prepaid calling card solutions

NASA Astrophysics Data System (ADS)

Gunadi, Tri

2001-07-01

The VoIP technology is growing up rapidly, it has big network impact on PT Telkom Indonesia, the bigger telecommunication operator in Indonesia. Telkom has adopted VoIP and one other technology, Intelligent Network (IN). We develop those technologies together in one service product, called Internet Prepaid Calling Card (IPCC). IPCC is becoming new breakthrough for the Indonesia telecommunication services especially on VoIP and Prepaid Calling Card solutions. Network architecture of Indonesia telecommunication consists of three layer, Local, Tandem and Trunck Exchange layer. Network development researches for IPCC architecture are focus on network overlay hierarchy, Internet and PSTN. With this design hierarchy the goal of Interworking PSTN, VoIP and IN calling card, become reality. Overlay design for IPCC is not on Trunck Exchange, this is the new architecture, these overlay on Tandem and Local Exchange, to make the faster call processing. The nodes added: Gateway (GW) and Card Management Center (CMC) The GW do interfacing between PSTN and Internet Network used ISDN-PRA and Ethernet. The other functions are making bridge on circuit (PSTN) with packet (VoIP) based and real time billing process. The CMC used for data storage, pin validation, report activation, tariff system, directory number and all the administration transaction. With two nodes added the IPCC service offered to the market.

Applying Tandem Mass Spectral Libraries for Solving the Critical Assessment of Small Molecule Identification (CASMI) LC/MS Challenge 2012

PubMed Central

Oberacher, Herbert

2013-01-01

The “Critical Assessment of Small Molecule Identification” (CASMI) contest was aimed in testing strategies for small molecule identification that are currently available in the experimental and computational mass spectrometry community. We have applied tandem mass spectral library search to solve Category 2 of the CASMI Challenge 2012 (best identification for high resolution LC/MS data). More than 230,000 tandem mass spectra part of four well established libraries (MassBank, the collection of tandem mass spectra of the “NIST/NIH/EPA Mass Spectral Library 2012”, METLIN, and the ‘Wiley Registry of Tandem Mass Spectral Data, MSforID’) were searched. The sample spectra acquired in positive ion mode were processed. Seven out of 12 challenges did not produce putative positive matches, simply because reference spectra were not available for the compounds searched. This suggests that to some extent the limited coverage of chemical space with high-quality reference spectra is still a problem encountered in tandem mass spectral library search. Solutions were submitted for five challenges. Three compounds were correctly identified (kanamycin A, benzyldiphenylphosphine oxide, and 1-isopropyl-5-methyl-1H-indole-2,3-dione). In the absence of any reference spectrum, a false positive identification was obtained for 1-aminoanthraquinone by matching the corresponding sample spectrum to the structurally related compounds N-phenylphthalimide and 2-aminoanthraquinone. Another false positive result was submitted for 1H-benz[g]indole; for the 1H-benz[g]indole-specific sample spectra provided, carbazole was listed as the best matching compound. In this case, the quality of the available 1H-benz[g]indole-specific reference spectra was found to hamper unequivocal identification. PMID:24957994

Protein denaturation improves enzymatic digestion efficiency for direct tissue analysis using mass spectrometry

NASA Astrophysics Data System (ADS)

Setou, M.; Hayasaka, T.; Shimma, S.; Sugiura, Y.; Matsumoto, M.

2008-12-01

Molecular identification using high-sensitivity tandem mass spectrometry is essential for protein analysis on the tissue surface. Here we report an improved digestion protocol for protein identification directly on the tissue surface using mass spectrometry. By denaturation process and the use of detergent-supplemented trypsin solution, we could successfully detect and identify many molecules such as tubulin, neurofilament, and synaptosomal-associated 25 kDa protein directly from a mouse cerebellum section.

A liquid chromatography - tandem mass spectrometry method to measure a selected panel of uremic retention solutes derived from endogenous and colonic microbial metabolism.

PubMed

de Loor, Henriette; Poesen, Ruben; De Leger, Wout; Dehaen, Wim; Augustijns, Patrick; Evenepoel, Pieter; Meijers, Björn

2016-09-14

Chronic kidney disease (CKD) is associated with an increased risk of mortality and cardiovascular disease, which is, at least partly, mediated by the accumulation of so-called uremic retention solutes. Although there has been an increasing interest in the behavior of these solutes, derived from both the endogenous and colonic microbial metabolism, methods to simultaneously and accurately measure a broad panel of relevant uremic retention solutes remain scarce. We developed a highly sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. A high throughput sample preparation was used with extraction of analytes from 50 μl serum using Ostro plate technology. For most solutes, stable isotopes labelled metabolites were used as internal standards. Chromatography was achieved using an Acquity UPLC CSH Fluoro Phenyl column. The total run time was 8 min, the mobile phase was a gradient of 0.1% formic acid in Milli-Q water and pure methanol at a flow rate of 0.5 ml min(-1). Detection was performed using a tandem mass spectrometer with alternated positive and negative electrospray ionization. Calibration curves were linear for all solutes. Precision was assessed according to the NCCLS EP5-T guideline, being below 15% for all metabolites. Mean recoveries were between 83 and 104% for all metabolites. The validated method was successfully applied in a cohort of 488 patients with CKD. We developed and validated a sensitive and robust UPLC-MS/MS method for quantification of 15 uremic retention solutes derived from endogenous and colonic microbial metabolism. This method allows for studying the behavior and relevance of these solutes in patients with CKD. Copyright © 2016 Elsevier B.V. All rights reserved.

Removal of six pesticide residues in cowpea with alkaline electrolysed water.

PubMed

Han, Yongtao; Song, Le; An, Quanshun; Pan, Canping

2017-06-01

Reduction of six pesticide residues (isoprocarb, chlorpyrifos, bifenthrin, beta-cypermethrin, difenoconazole and azoxystrobin) in cowpea by alkaline electrolysed water (AlEW) solutions with different pH was investigated. The commonly used washing treatments in household processing were used for comparison. The residue magnitudes were determined by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). Results showed that the removal effect of AlEW solution on the six pesticides was superior to tap water, 5% sodium chloride, 5% sodium carbonate and 5% acetic acid solution. AlEW with pH 12.2 had more potential to eliminate the six pesticides in cowpeas. Moreover, the reduction of pesticide residues gradually increased with the increase of washing time. This study demonstrated that AlEW solution with pH of 12.2 could be used to reduce pesticide residues on fresh cowpea samples. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Alkaline-side extraction of technetium from tank waste using crown ethers and other extractants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonnesen, P.V.; Moyer, B.A.; Presley, D.J.

The chemical development of a new crown-ether-based solvent-extraction process for the separation of (Tc) from alkaline tank-waste supernate is ready for counter-current testing. The process addresses a priority need in the proposed cleanup of Hanford and other tank wastes. This need has arisen from concerns due to the volatility of Tc during vitrification, as well as {sup 99}Tc`s long half-life and environmental mobility. The new process offers several key advantages that direct treatability--no adjustment of the waste composition is needed; economical stripping with water; high efficiency--few stages needed; non-RCRA chemicals--no generation of hazardous or mixed wastes; co-extraction of {sup 90}Sr;more » and optional concentration on a resin. A key concept advanced in this work entails the use of tandem techniques: solvent extraction offers high selectivity, while a subsequent column sorption process on the aqueous stripping solution serves to greatly concentrate the Tc. Optionally, the stripping solution can be evaporated to a small volume. Batch tests of the solvent-extraction and stripping components of the process have been conducted on actual melton Valley Storage Tank (MVST) waste as well as simulants of MVST and Hanford waste. The tandem process was demonstrated on MVST waste simulants using the three solvents that were selected the final candidates for the process. The solvents are 0.04 M bis-4,4{prime}(5{prime})[(tert-butyl)cyclohexano]-18-crown-6 (abbreviated di-t-BuCH18C6) in a 1:1 vol/vol blend of tributyl phosphate and Isopar{reg_sign} M (an isoparaffinic kerosene); 0.02 M di-t-BuCH18C6 in 2:1 vol/vol TBP/Isopar M and pure TBP. The process is now ready for counter-current testing on actual Hanford tank supernates.« less

Characterization of perovskite layer on various nanostructured silicon wafer

NASA Astrophysics Data System (ADS)

Rostan, Nur Fairuz Mohd; Sepeai, Suhaila; Ramli, Noor Fadhilah; Azhari, Ayu Wazira; Ludin, Norasikin Ahmad; Teridi, Mohd Asri Mat; Ibrahim, Mohd Adib; Zaidi, Saleem H.

2017-05-01

Crystalline silicon (c-Si) solar cell dominates 90% of photovoltaic (PV) market. The c-Si is the most mature of all PV technologies and expected to remain leading the PV technology by 2050. The attractive characters of Si solar cell are stability, long lasting and higher lifetime. Presently, the efficiency of c-Si solar cell is still stuck at 25% for one and half decades. Tandem approach is one of the attempts to improve the Si solar cell efficiency with higher bandgap layer is stacked on top of Si bottom cell. Perovskite offers a big potential to be inserted into a tandem solar cell. Perovskite with bandgap of 1.6 to 1.9 eV will be able to absorb high energy photons, meanwhile c-Si with bandgap of 1.124 eV will absorb low energy photons. The high carrier mobility, high carrier lifetime, highly compatible with both solution and evaporation techniques makes perovskite an eligible candidate for perovskite-Si tandem configuration. The solution of methyl ammonium lead iodide (MAPbI3) was prepared by single step precursor process. The perovskite layer was deposited on different c-Si surface structure, namely planar, textured and Si nanowires (SiNWs) by using spin-coating technique at different rotation speeds. The nanostructure of Si surface was textured using alkaline based wet chemical etching process and SiNW was grown using metal assisted etching technique. The detailed surface morphology and absorbance of perovskite were studied in this paper. The results show that the thicknesses of MAPbI3 were reduced with the increasing of rotation speed. In addition, the perovskite layer deposited on the nanostructured Si wafer became rougher as the etching time and rotation speed increased. The average surface roughness increased from ˜24 nm to ˜38 nm for etching time range between 5-60 min at constant low rotation speed (2000 rpm) for SiNWs Si wafer.

Tunable color parallel tandem organic light emitting devices with carbon nanotube and metallic sheet interlayers

NASA Astrophysics Data System (ADS)

Oliva, Jorge; Papadimitratos, Alexios; Desirena, Haggeo; De la Rosa, Elder; Zakhidov, Anvar A.

2015-11-01

Parallel tandem organic light emitting devices (OLEDs) were fabricated with transparent multiwall carbon nanotube sheets (MWCNT) and thin metal films (Al, Ag) as interlayers. In parallel monolithic tandem architecture, the MWCNT (or metallic films) interlayers are an active electrode which injects similar charges into subunits. In the case of parallel tandems with common anode (C.A.) of this study, holes are injected into top and bottom subunits from the common interlayer electrode; whereas in the configuration of common cathode (C.C.), electrons are injected into the top and bottom subunits. Both subunits of the tandem can thus be monolithically connected functionally in an active structure in which each subunit can be electrically addressed separately. Our tandem OLEDs have a polymer as emitter in the bottom subunit and a small molecule emitter in the top subunit. We also compared the performance of the parallel tandem with that of in series and the additional advantages of the parallel architecture over the in-series were: tunable chromaticity, lower voltage operation, and higher brightness. Finally, we demonstrate that processing of the MWCNT sheets as a common anode in parallel tandems is an easy and low cost process, since their integration as electrodes in OLEDs is achieved by simple dry lamination process.

Control of surface thermal scratch of strip in tandem cold rolling

NASA Astrophysics Data System (ADS)

Chen, Jinshan; Li, Changsheng

2014-07-01

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.

Unexpected formation of 2,1-benzisothiazol-3-ones from oxathiolano ketenimines: a rare tandem process.

PubMed

Alajarin, Mateo; Bonillo, Baltasar; Sanchez-Andrada, Pilar; Vidal, Angel; Bautista, Delia

2009-03-19

A rare one-pot reaction, a tandem [1,5]-H shift/1,5 electrocyclization/[3 + 2] cycloreversion process, leading from N-[2-(1,3-oxathiolan-2-yl)]phenyl ketenimines to 1-(beta-styryl)-2,1-benzisothiazol-3-ones and ethylene, is disclosed and mechanistically unraveled by means of a computational DFT study. The two latter stages of the tandem process are calculated to occur in a single mechanistic step via a transition structure of pseudopericyclic characteristics.

Simultaneous quantitation and identification of organic and inorganic selenium in diet supplements by liquid chromatography with tandem mass spectrometry.

PubMed

Zembrzuska, Joanna; Matusiewicz, Henryk; Polkowska-Motrenko, Halina; Chajduk, Ewelina

2014-01-01

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for selenium speciation in dietary supplements. Chromatographic separation was performed on a TSK-Gel ODS-100V column using a mixture of 5mM ammonium acetate water solution and methanol as a mobile phase. Conditions chosen for this process allowed to separate all investigated chemical compounds of selenium: seleno-l-methionine, methyl-seleno-l-cysteine, l-selenocystine, methaneseleninic acid, selenite and selenate. A tandem mass spectrometer with an ion trap operating in negative or positive ion mode according to the selenium form being determined was used as a detector. Three extraction procedures: water extraction, enzymatic hydrolysis and sequential extraction were used for preparation of samples for the determination of the actual forms of selenium in diet supplements. The developed method was used for analysis of six dietary supplements containing selenium bought in a pharmacy and supermarket. Apart from speciation analysis of selenium content in supplements total selenium content was determined using instrumental neutron activation analysis (INAA). All expected forms of selenium except for selenite were determined using LC-MS/MS technique. It should be stressed that amounts of selenate were smaller than expected. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thermodynamic efficiency limits of classical and bifacial multi-junction tandem solar cells: An analytical approach

NASA Astrophysics Data System (ADS)

Alam, Muhammad Ashraful; Khan, M. Ryyan

2016-10-01

Bifacial tandem cells promise to reduce three fundamental losses (i.e., above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction photovoltaic (PV) systems. The successive filtering of light through the bandgap cascade and the requirement of current continuity make optimization of tandem cells difficult and accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple analytical approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can be obtained with a few lines of algebra. This powerful approach reproduces, as special cases, all of the known results of conventional and bifacial tandem cells and highlights the asymptotic efficiency gain of these technologies.

Efficient Monolithic Perovskite/Silicon Tandem Solar Cell with Cell Area >1 cm(2).

PubMed

Werner, Jérémie; Weng, Ching-Hsun; Walter, Arnaud; Fesquet, Luc; Seif, Johannes Peter; De Wolf, Stefaan; Niesen, Bjoern; Ballif, Christophe

2016-01-07

Monolithic perovskite/crystalline silicon tandem solar cells hold great promise for further performance improvement of well-established silicon photovoltaics; however, monolithic tandem integration is challenging, evidenced by the modest performances and small-area devices reported so far. Here we present first a low-temperature process for semitransparent perovskite solar cells, yielding efficiencies of up to 14.5%. Then, we implement this process to fabricate monolithic perovskite/silicon heterojunction tandem solar cells yielding efficiencies of up to 21.2 and 19.2% for cell areas of 0.17 and 1.22 cm(2), respectively. Both efficiencies are well above those of the involved subcells. These single-junction perovskite and tandem solar cells are hysteresis-free and demonstrate steady performance under maximum power point tracking for several minutes. Finally, we present the effects of varying the intermediate recombination layer and hole transport layer thicknesses on tandem cell photocurrent generation, experimentally and by transfer matrix simulations.

Ultra-high performance liquid chromatography tandem high-resolution mass spectrometry study of tricyclazole photodegradation products in water.

PubMed

Gosetti, Fabio; Chiuminatto, Ugo; Mazzucco, Eleonora; Mastroianni, Rita; Bolfi, Bianca; Marengo, Emilio

2015-06-01

This paper reports the study of the photodegradation reactions that tricyclazole can naturally undergo, under the action of sunlight, in aqueous solutions of standard tricyclazole and of the commercial BEAM(TM) formulation. The analyses are carried out by ultra-high performance liquid chromatography technique coupled with high-resolution tandem mass spectrometry. Analysis of both tricyclazole and BEAM(TM) water solutions undergone to hydrolysis does not evidence new chromatographic peaks with respect to the not treated solutions. On the contrary, analysis of the same samples subjected to sunlight irradiation shows a decreased intensity of tricyclazole signal and the presence of new chromatographic peaks. Two photodegradation products of tricyclazole have been identified, one of which has been also quantified, being the commercial standard available. The pattern is similar for the solutions of the standard fungicide and of the BEAM(TM) formulation. The results obtained from eco-toxicological tests show that toxicity of tricyclazole standard solutions is greater than that of the irradiated ones, whereas toxicity levels of all the BEAM(TM) solutions investigated (non-irradiated, irradiated, and hydrolyzed) are comparable and lower than those shown by tricyclazole standard solutions. Experiments performed in paddy water solution show that there is no difference in the degradation products formed.

Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots

NASA Astrophysics Data System (ADS)

Pach, Gregory F.

Colloidal quantum dots (QDs) are a widely investigated field of research due to their highly tunable nature in which the optical and electronic properties of the nanocrystal can be manipulated by merely changing the nanocrystal's size. Specifically, colloidal quantum dot solar cells (QDSCs) have become a promising candidate for future generation photovoltaic technology. Quantum dots exhibit multiple exciton generation (MEG) in which multiple electron-hole pairs are generated from a single high-energy photon. This process is not observed in bulk-like semiconductors and allows for QDSCs to achieve theoretical efficiency limits above the standard single-junction Shockley-Queisser limit. However, the fast expanding field of QDSC research has lacked standardization of synthetic techniques and device design. Therefore, we sought to detail methodology for synthesizing PbS and PbSe QDs as well as photovoltaic device fabrication techniques as a fast track toward constructing high-performance solar cells. We show that these protocols lead toward consistently achieving efficiencies above 8% for PbS QDSCs. Using the same methodology for building single-junction photovoltaic devices, we incorporated PbS QDs as a bottom cell into a monolithic tandem architecture along with solution-processed CdTe nanocrystals. Modeling shows that near-peak tandem device efficiencies can be achieved across a wide range of bottom cell band gaps, and therefore the highly tunable band gap of lead-chalcogenide QDs lends well towards a bottom cell in a tandem architecture. A fully functioning monolithic tandem device is realized through the development of a ZnTe/ZnO recombination layer that appropriately combines the two subcells in series. Multiple recent reports have shown nanocrystalline heterostructures to undergo the MEG process more efficiency than several other nanostrucutres, namely lead-chalcogenide QDs. The final section of my thesis expands upon a recent publication by Zhang et. al., which details the synthesis of PbS/CdS heterostructures in which the PbS and CdS domains exist on opposite sides of the nanocrystal and are termed "Janus particles". Transient absorption spectroscopy shows MEG quantum yields above unity very the thermodynamic limit of 2Eg for PbS/CdS Janus particles. We further explain a mechanism for enhanced MEG using photoluminescence studies.

Tandem catalysis: a new approach to polymers.

PubMed

Robert, Carine; Thomas, Christophe M

2013-12-21

The creation of polymers by tandem catalysis represents an exciting frontier in materials science. Tandem catalysis is one of the strategies used by Nature for building macromolecules. Living organisms generally synthesize macromolecules by in vivo enzyme-catalyzed chain growth polymerization reactions using activated monomers that have been formed within cells during complex metabolic processes. However, these biological processes rely on highly complex biocatalysts, thus limiting their industrial applications. In order to obtain polymers by tandem catalysis, homogeneous and enzyme catalysts have played a leading role in the last two decades. In the following feature article, we will describe selected published efforts to achieve these research goals.

Summary of the Tandem Cylinder Solutions from the Benchmark Problems for Airframe Noise Computations-I Workshop

NASA Technical Reports Server (NTRS)

Lockard, David P.

2011-01-01

Fifteen submissions in the tandem cylinders category of the First Workshop on Benchmark problems for Airframe Noise Computations are summarized. Although the geometry is relatively simple, the problem involves complex physics. Researchers employed various block-structured, overset, unstructured and embedded Cartesian grid techniques and considerable computational resources to simulate the flow. The solutions are compared against each other and experimental data from 2 facilities. Overall, the simulations captured the gross features of the flow, but resolving all the details which would be necessary to compute the noise remains challenging. In particular, how to best simulate the effects of the experimental transition strip, and the associated high Reynolds number effects, was unclear. Furthermore, capturing the spanwise variation proved difficult.

Towards a fully synthetic substitute of alginate: optimization of a thermal gelation/chemical cross-linking scheme ("tandem" gelation) for the production of beads and liquid-core capsules.

PubMed

Cellesi, F; Weber, W; Fussenegger, M; Hubbell, J A; Tirelli, N

2004-12-20

Fully synthetic polymers were used for the preparation of hydrogel beads and capsules, in a processing scheme that, originally designed for calcium alginate, was adapted to a "tandem" process, that is the combination a physical gelation with a chemical cross-linking. The polymers feature a Tetronic backbone (tetra armed Pluronics), which exhibits a reverse thermal gelation in water solutions within a physiological range of temperatures and pHs. The polymers bear terminal reactive groups that allow for a mild, but effective chemical cross-linking. Given an appropriate temperature jump, the thermal gelation provides a hardening kinetics similar to that of alginate. With slower kinetics, the chemical cross-linking then develops an irreversible and elastic gel structure, and determines its transport properties. In the present article this process has been optimized for the production of monodisperse, high elastic, hydrogel microbeads, and liquid-core microcapsules. We also show the feasibility of the use of liquid-core microcapsules in cell encapsulation. In preliminary experiments, CHO cells have been successfully encapsulated preserving their viability during the process and after incubation. The advantages of this process are mainly in the use of synthetic polymers, which provide great flexibility in the molecular design. This, in principle, allows for a precise tailoring of mechanical and transport properties and of bioactivity of the hydrogels, and also for a precise control in material purification.

A novel signal transduction protein: Combination of solute binding and tandem PAS-like sensor domains in one polypeptide chain

DOE PAGES

Wu, R.; Wilton, R.; Cuff, M. E.; ...

2017-02-07

The tandem Per-Arnt-Sim (PAS) like sensors are commonly found in signal transduction proteins. The periplasmic solute binding protein (SBP) domains are found ubiquitously and are generally involved in solute transport. These domains are widely observed as parts of separate proteins but not within the same polypeptide chain. We report the structural and biochemical characterization of the extracellular ligand-binding receptor, Dret_0059 from Desulfohalobium retbaense DSM 5692, an organism isolated from the Retba salt lake in Senegal. The structure of Dret_0059 consists of a novel combination of SBP and TPAS sensor domains. The N-terminal region forms an SBP domain and the C-terminalmore » region folds into a tandem PAS-like domain structure. A ketoleucine moiety is bound to the SBP, whereas a cytosine molecule is bound in the distal PAS domain of the TPAS. The differential scanning flourimetry studies in solution support the ligands observed in the crystal structure. There are only two other proteins with this structural architecture in the non-redundant sequence data base and we predict that they too bind the same substrates. There is significant interaction between the SBP and TPAS domains, and it is quite conceivable that the binding of one ligand will have an effect on the binding of the other. Our attempts to remove the ligands bound to the protein during expression were not successful, therefore, it is not clear what the relative affects are. The genomic context of this receptor does not contain any protein components expected for transport function, hence, we suggest that Dret_0059 is likely involved in signal transduction and not in solute transport.« less

Stability of Ribavirin for Inhalation Packaged in Syringes or Glass Vials when Stored Frozen, Refrigerated, and at Room Temperature.

PubMed

Larson, Bayli; Bushman, Lane R; Casciano, Matthew L; Oldland, Alan R; Kiser, Jennifer J; Kiser, Tyree H

2016-01-01

The primary aim of this study was to investigate ribavirin solution for inhalation stability under three different conditions (frozen, refrigerated, room temperature) over a 45-day period. A ribavirin 6000-mg vial was reconstituted with 90 mL of Sterile Water for Injection per the package insert to yield a concentration of approximately 67 mg/mL. The solution was then placed in either syringes or empty glass vials and stored in the freezer (-20°C), in the refrigerator (~0°C to 4°C), or at room temperature (~20°C to 25°C). Original concentrations were measured on day 0 and subsequent concentrations were measured on day 2, 14, and 45 utilizing a validated liquid chromatography with tandem mass spectrometry assay. All analyses were performed in triplicate for each storage condition. Additionally, at each time point the physical stability was evaluated and the pH of solution was measured. The solution was considered stable if =90% of the original concentration was retained over the study period. A validated liquid chromatography with tandem mass spectrometry analysis demonstrated that >95% of the original ribavirin concentration was preserved over the 45-day period for all study conditions. The ribavirin concentration remained within the United States Pharmacopeia (USP)-required range of 95% to 105% of the original labeled product amount throughout the entire study period for all study conditions. Precipitation of ribavirin was noted during the thawing cycle for frozen samples, but the drug went back into solution once the thawing process was completed. No changes in color or turbidity were observed in any of the prepared solutions. Values for pH remained stable over the study period and ranged from 4.1 to 5.3. Ribavirin for inhalation solution is physically and chemically stable for at least 45 days when frozen, refrigerated, or kept at room temperature after reconstitution to a concentration of approximately 67 mg/mL and placed in syringes or glass vials. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Structure and Function of the Two Tandem WW Domains of the Pre-mRNA Splicing Factor FBP21 (Formin-binding Protein 21)*

PubMed Central

Huang, Xiaojuan; Beullens, Monique; Zhang, Jiahai; Zhou, Yi; Nicolaescu, Emilia; Lesage, Bart; Hu, Qi; Wu, Jihui; Bollen, Mathieu; Shi, Yunyu

2009-01-01

Human FBP21 (formin-binding protein 21) contains a matrin-type zinc finger and two tandem WW domains. It is a component of the spliceosomes and interacts with several established splicing factors. Here we demonstrate for the first time that FBP21 is an activator of pre-mRNA splicing in vivo and that its splicing activation function and interaction with the splicing factor SIPP1 (splicing factor that interacts with PQBP1 and PP1) are both mediated by the two tandem WW domains of group III. We determined the solution structure of the tandem WW domains of FBP21 and found that the WW domains recognize peptide ligands containing either group II (PPLP) or group III (PPR) motifs. The binding interfaces involve both the XP and XP2 grooves of the two WW domains. Significantly, the tandem WW domains of FBP21 are connected by a highly flexible region, enabling their simultaneous interaction with two proline-rich motifs of SIPP1. The strong interaction between SIPP1 and FBP21 can be explained by the conjugation of two low affinity interactions with the tandem WW domains. Our study provides a structural basis for understanding the molecular mechanism underlying the functional implication of FBP21 and the biological specificity of tandem WW domains. PMID:19592703

Tandem Lewis/Brønsted homogeneous acid catalysis: conversion of glucose to 5-hydoxymethylfurfural in an aqueous chromium(iii) chloride and hydrochloric acid solution

DOE PAGES

Swift, T. Dallas; Nguyen, Hannah; Anderko, Andrzej; ...

2015-07-25

Here, a kinetic model for the tandem conversion of glucose to 5-hydroxymethylfurfural (HMF) through fructose in aqueous CrCl 3–HCl solution was developed by analyzing experimental data. We show that the coupling of Lewis and Brønsted acids in a single pot overcomes equilibrium limitations of the glucose–fructose isomerization leading to high glucose conversions and identify conditions that maximize HMF yield. Adjusting the HCl/CrCl 3 concentration has a more pronounced effect on HMF yield at constant glucose conversion than that of temperature or CrCl 3 concentration. This is attributed to the interactions between HCl and CrCl 3 speciation in solution that leadsmore » to HMF yield being maximized at moderate HCl concentrations for each CrCl 3 concentration. This volcano-like behavior is accompanied with a change in the rate-limiting step from fructose dehydration to glucose isomerization as the concentration of the Brønsted acid increases. The maximum HMF yield in a single aqueous phase is only modest and appears independent of catalysts’ concentrations as long as they are appropriately balanced. However, it can be further maximized in a biphasic system. Our findings are consistent with recent studies in other tandem reactions catalyzed by different catalysts.« less

Tandem Lewis/Brønsted homogeneous acid catalysis: conversion of glucose to 5-hydoxymethylfurfural in an aqueous chromium(iii) chloride and hydrochloric acid solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swift, T. Dallas; Nguyen, Hannah; Anderko, Andrzej

Here, a kinetic model for the tandem conversion of glucose to 5-hydroxymethylfurfural (HMF) through fructose in aqueous CrCl 3–HCl solution was developed by analyzing experimental data. We show that the coupling of Lewis and Brønsted acids in a single pot overcomes equilibrium limitations of the glucose–fructose isomerization leading to high glucose conversions and identify conditions that maximize HMF yield. Adjusting the HCl/CrCl 3 concentration has a more pronounced effect on HMF yield at constant glucose conversion than that of temperature or CrCl 3 concentration. This is attributed to the interactions between HCl and CrCl 3 speciation in solution that leadsmore » to HMF yield being maximized at moderate HCl concentrations for each CrCl 3 concentration. This volcano-like behavior is accompanied with a change in the rate-limiting step from fructose dehydration to glucose isomerization as the concentration of the Brønsted acid increases. The maximum HMF yield in a single aqueous phase is only modest and appears independent of catalysts’ concentrations as long as they are appropriately balanced. However, it can be further maximized in a biphasic system. Our findings are consistent with recent studies in other tandem reactions catalyzed by different catalysts.« less

Achieving high performance polymer tandem solar cells via novel materials design

NASA Astrophysics Data System (ADS)

Dou, Letian

Organic photovoltaic (OPV) devices show great promise in low-cost, flexible, lightweight, and large-area energy-generation applications. Nonetheless, most of the materials designed today always suffer from the inherent disadvantage of not having a broad absorption range, and relatively low mobility, which limit the utilization of the full solar spectrum. 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 suitable low-bandgap polymers (near-IR absorbing polymers). In this dissertation, in order to achieve high performance, we focus on design and synthesis of novel low bandgap polymers specifically for tandem solar cells. In Chapter 3, I demonstrate highly efficient single junction and tandem polymer solar cells featuring a spectrally matched low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ˜1.44 eV). The polymer has a backbone based on alternating benzodithiophene and diketopyrrolopyrrole units. A single-layer device based on the polymer provides a power conversion efficiency of ˜6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved, which was the highest certified efficiency for a polymer solar cell. To further improve this material system, in Chapter 4, I show that the reduction of the bandgap and the enhancement of the charge transport properties of the low bandgap polymer PBDTT-DPP can be accomplished simultaneously by substituting the sulfur atoms on the DPP unit with selenium atoms. The newly designed polymer PBDTT-SeDPP (Eg = 1.38 eV) shows excellent photovoltaic performance in single junction devices with PCEs over 7% and photo-response up to 900 nm. Tandem polymer solar cells based on PBDTT-SeDPP are also demonstrated with a 9.5% PCE, which are more than 10% enhancement over those based on PBDTT-DPP. Finally, in Chapter 5, I demonstrate a new polymer system based on alternating dithienopyran and benzothiadiazole units 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, which is the first certified polymer solar cell efficiency over 10%.

Identification of mutagenic transformation products generated during oxidation of 3-methyl-4-nitrophenol solutions by orbitrap tandem mass spectrometry and quantitative structure-activity relationship analyses.

PubMed

Matsushita, Taku; Honda, Shiho; Kuriyama, Taisuke; Fujita, Yuki; Kondo, Takashi; Matsui, Yoshihiko; Shirasaki, Nobutaka; Takanashi, Hirokazu; Kameya, Takashi

2018-02-01

We used Ames assays to investigate the effects of ozonation (designated O 3 ), ozonation followed by chlorination (O 3 /Cl), an advanced oxidation process (AOP, UV/H 2 O 2 ), and AOP followed by chlorination (AOP/Cl) on the mutagenicity of solutions of 3-methyl-4-nitrophenol (3M4NP), a major environmental degradation product of the organophosphorus insecticide fenitrothion. Whereas O 3 did not induce mutagenicity, O 3 /Cl, AOP, and AOP/Cl converted 3M4NP into mutagenic transformation products (TPs). Using liquid chromatography-mass spectrometry, we detected a total of 138 peaks in the solutions subjected to O 3 /Cl, AOP, and AOP/Cl. To elucidate the TPs responsible for the observed mutagenicity, we performed simple regression analyses of the relationship between the area of each peak and the observed mutagenicity of samples withdrawn periodically during each oxidation process. The area of each of 10 peaks was found to be positively correlated (r 2  ≥ 0.8) with the observed mutagenicity, suggesting that the TPs corresponding to these peaks contributed to the mutagenicity. After taking into account the consistency of mutagenicity induction by the oxidation processes and analyzing the peaks by tandem mass spectrometry, we identified 3 TPs, corresponding to 6 peaks, as candidate mutagens. These TPs were assessed by means of 4 quantitative structure-activity relationship (QSAR) models, and all 3 were predicted to be mutagenic by at least one model. This result was consistent with our assumption that these TPs were mutagens. Ames assays of an authentic sample of one of the 3 TPs revealed that it did not contribute to the mutagenicity. This left 3-methoxy-4-nitrophenol and 2-[(E)-[(2,5-dihydroxyphenyl) methylidene]amino]-5-dihydroxybenzaldehyde on the list of mutagens suspected of contributing to the mutagenicity induced by AOP. No TPs were identified as candidate mutagens responsible for the mutagenicity induced by O 3 /Cl and AOP/Cl. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular solution processing of metal chalcogenide thin film solar cells

NASA Astrophysics Data System (ADS)

Yang, Wenbing

The barrier to utilize solar generated electricity mainly comes from their higher cost relative to fossil fuels. However, innovations with new materials and processing techniques can potentially make cost effective photovoltaics. One such strategy is to develop solution processed photovoltaics which avoid the expensive vacuum processing required by traditional solar cells. The dissertation is mainly focused on two absorber material system for thin film solar cells: chalcopyrite CuIn(S,Se)2 (CISS) and kesterite Cu2ZnSn(S,Se) 4 organized in chronological order. Chalcopyrite CISS is a very promising material. It has been demonstrated to achieve the highest efficiency among thin film solar cells. Scaled-up industry production at present has reached the giga-watt per year level. The process however mainly relies on vacuum systems which account for a significant percentage of the manufacturing cost. In the first section of this dissertation, hydrazine based solution processed CISS has been explored. The focus of the research involves the procedures to fabricate devices from solution. The topics covered in Chapter 2 include: precursor solution synthesis with a focus on understanding the solution chemistry, CISS absorber formation from precursor, properties modification toward favorable device performance, and device structure innovation toward tandem device. For photovoltaics to have a significant impact toward meeting energy demands, the annual production capability needs to be on TW-level. On such a level, raw materials supply of rare elements (indium for CIS or tellurium for CdTe) will be the bottleneck limiting the scalability. Replacing indium with zinc and tin, earth abundant kesterite CZTS exhibits great potential to reach the goal of TW-level with no limitations on raw material availability. Chapter 3 shows pioneering work towards solution processing of CZTS film at low temperature. The solution processed devices show performances which rival vacuum-based techniques and is partially attributed to the ease in controlling composition and CZTS phase through this technique. Based on this platform, comprehensive characterization on CZTS devices is carried out including solar cells and transistors. Especially defects properties are exploited in Chapter 4 targeting to identify the limiting factors for further improvement on CZTS solar cells efficiency. Finally, molecular structures and precursor solution stability have been explored, potentially to provide a universal approach to process multinary compounds.

Matrix effect on the determination of synthetic corticosteroids and diuretics by liquid chromatography-tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Dikunets, M. A.; Appolonova, S. A.; Rodchenkov, G. M.

2009-04-01

This work presents a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) procedure for selective and reliable screening of corticosteroids and diuretics in human urine. Sample preparation included the extraction, evaporation of the organic extract under nitrogen, and solution of the dry residue. The extract was analyzed by HPLC combined with tandem mass spectrometry using electro-spraying ionization at atmospheric pressure with negative ion recording. The mass spectra of all compounds were recorded, and the characteristic ions, retention times, and detection limits were determined. The procedure was validated by evaluating the degree of the matrix suppression of ionization, extraction of analytes from human biological liquid, and the selectivity and specificity of determination.

Orthogonal tandem catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lohr, Tracy L.; Marks, Tobin J.

2015-05-20

Tandem catalysis is a growing field that is beginning to yield important scientific and technological advances toward new and more efficient catalytic processes. 'One-pot' tandem reactions, where multiple catalysts and reagents, combined in a single reaction vessel undergo a sequence of precisely staged catalytic steps, are highly attractive from the standpoint of reducing both waste and time. Orthogonal tandem catalysis is a subset of one-pot reactions in which more than one catalyst is used to promote two or more mechanistically distinct reaction steps. This Perspective summarizes and analyses some of the recent developments and successes in orthogonal tandem catalysis, withmore » particular focus on recent strategies to address catalyst incompatibility. We also highlight the concept of thermodynamic leveraging by coupling multiple catalyst cycles to effect challenging transformations not observed in single-step processes, and to encourage application of this technique to energetically unfavourable or demanding reactions.« less

Standing wave design and experimental validation of a tandem simulated moving bed process for insulin purification.

PubMed

Xie, Yi; Mun, Sungyong; Kim, Jinhyun; Wang, Nien-Hwa Linda

2002-01-01

A tandem simulated moving bed (SMB) process for insulin purification has been proposed and validated experimentally. The mixture to be separated consists of insulin, high molecular weight proteins, and zinc chloride. A systematic approach based on the standing wave design, rate model simulations, and experiments was used to develop this multicomponent separation process. The standing wave design was applied to specify the SMB operating conditions of a lab-scale unit with 10 columns. The design was validated with rate model simulations prior to experiments. The experimental results show 99.9% purity and 99% yield, which closely agree with the model predictions and the standing wave design targets. The agreement proves that the standing wave design can ensure high purity and high yield for the tandem SMB process. Compared to a conventional batch SEC process, the tandem SMB has 10% higher yield, 400% higher throughput, and 72% lower eluant consumption. In contrast, a design that ignores the effects of mass transfer and nonideal flow cannot meet the purity requirement and gives less than 96% yield.

Continuous formation of N-chloro-N,N-dialkylamine solutions in well-mixed meso-scale flow reactors

PubMed Central

Jolley, Katherine E

2015-01-01

Summary The continuous flow synthesis of a range of organic solutions of N,N-dialkyl-N-chloramines is described using either a bespoke meso-scale tubular reactor with static mixers or a continuous stirred tank reactor. Both reactors promote the efficient mixing of a biphasic solution of N,N-dialkylamine in organic solvent, and aqueous sodium hypochlorite to achieve near quantitative conversions, in 72–100% in situ yields, and useful productivities of around 0.05 mol/h with residence times from 3 to 20 minutes. Initial calorimetric studies have been carried out to inform on reaction exotherms, rates and safe operation. Amines which partition mainly in the organic phase require longer reaction times, provided by the CSTR, to compensate for low mass transfer rates in the biphasic system. The green metrics of the reaction have been assessed and compared to existing procedures and have shown the continuous process is improved over previous procedures. The organic solutions of N,N-dialkyl-N-chloramines produced continuously will enable their use in tandem flow reactions with a range of nucleophilic substrates. PMID:26734089

Modified Amber Force Field Correctly Models the Conformational Preference for Tandem GA pairs in RNA

PubMed Central

2015-01-01

Molecular mechanics with all-atom models was used to understand the conformational preference of tandem guanine-adenine (GA) noncanonical pairs in RNA. These tandem GA pairs play important roles in determining stability, flexibility, and structural dynamics of RNA tertiary structures. Previous solution structures showed that these tandem GA pairs adopt either imino (cis Watson–Crick/Watson–Crick A-G) or sheared (trans Hoogsteen/sugar edge A-G) conformations depending on the sequence and orientation of the adjacent closing base pairs. The solution structures (GCGGACGC)2 [Biochemistry, 1996, 35, 9677–9689] and (GCGGAUGC)2 [Biochemistry, 2007, 46, 1511–1522] demonstrate imino and sheared conformations for the two central GA pairs, respectively. These systems were studied using molecular dynamics and free energy change calculations for conformational changes, using umbrella sampling. For the structures to maintain their native conformations during molecular dynamics simulations, a modification to the standard Amber ff10 force field was required, which allowed the amino group of guanine to leave the plane of the base [J. Chem. Theory Comput., 2009, 5, 2088–2100] and form out-of-plane hydrogen bonds with a cross-strand cytosine or uracil. The requirement for this modification suggests the importance of out-of-plane hydrogen bonds in stabilizing the native structures. Free energy change calculations for each sequence demonstrated the correct conformational preference when the force field modification was used, but the extent of the preference is underestimated. PMID:24803859

High Performance Tandem Perovskite/Polymer Solar Cells

NASA Astrophysics Data System (ADS)

Liu, Yao; Bag, Monojit; Page, Zachariah; Renna, Lawrence; Kim, Paul; Choi, Jaewon; Emrick, Todd; Venkataraman, D.; Russell, Thomas

Combining perovskites with other inorganic materials, such as copper indium gallium diselenide (CIGS) or silicon, is enabling significant improvement in solar cell device performance. Here, we demonstrate a highly efficient hybrid tandem solar cell fabricated through a facile solution deposition approach to give a perovskite front sub-cell and a polymer:fullerene blend back sub-cell. This methodology eliminates the adverse effects of thermal annealing during perovskite fabrication on polymer solar cells. The record tandem solar cell efficiency of 15.96% is 40% greater than the corresponding perovskite-based single junction device and 65% greater than the polymer-based single junction device, while mitigating deleterious hysteresis effects often associated with perovskite solar cells. The hybrid tandem devices demonstrate the synergistic effects arising from the combination of perovskite and polymer-based materials for solar cells. This work was supported by the Department of Energy-supported Energy Frontier Research Center at the University of Massachusetts (DE-SC0001087). The authors acknowledge the W.M. Keck Electron Microscopy.

Solution structure of the tandem acyl carrier protein domains from a polyunsaturated fatty acid synthase reveals beads-on-a-string configuration.

PubMed

Trujillo, Uldaeliz; Vázquez-Rosa, Edwin; Oyola-Robles, Delise; Stagg, Loren J; Vassallo, David A; Vega, Irving E; Arold, Stefan T; Baerga-Ortiz, Abel

2013-01-01

The polyunsaturated fatty acid (PUFA) synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP) domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect) and in structural stabilization of the multidomain protein (synergistic effect). While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS) revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of multiple ACP domains for increasing the yield of fatty acids in bacterial cultures.

Solution Structure of the Tandem Acyl Carrier Protein Domains from a Polyunsaturated Fatty Acid Synthase Reveals Beads-on-a-String Configuration

PubMed Central

Trujillo, Uldaeliz; Vázquez-Rosa, Edwin; Oyola-Robles, Delise; Stagg, Loren J.; Vassallo, David A.; Vega, Irving E.; Arold, Stefan T.; Baerga-Ortiz, Abel

2013-01-01

The polyunsaturated fatty acid (PUFA) synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP) domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect) and in structural stabilization of the multidomain protein (synergistic effect). While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS) revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of multiple ACP domains for increasing the yield of fatty acids in bacterial cultures. PMID:23469090

Optimization of Analytical Conditions for a Rapid Determination of Aniline in Environmental Water by Liquid Chromatography/Tandem Mass Spectrometry.

PubMed

Furukawa, Koji; Hashimoto, Makoto; Kaneco, Satoshi

2017-01-01

A rapid determination of aniline in environmental water was examined based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Environmental water samples were diluted 20-fold with Mill-Q water and measured by LC/MS/MS after adding a surrogate substance (aniline-d 5 ). In the results of the present study, the calibration curve of aniline showed good linearity in the range of 0.05 - 2.0 μg/L. Since the RSD (repeatability) by measuring repeatedly an aniline standard solution (0.05 μg/L, n = 7) was 3.2%, the repeatability of this work was very excellent. In addition, the recovery rate of aniline in environmental water was in the range of 99.0 - 102% with RSD 3.4 - 7.7%, and very good recovery test results were obtained. From these results, this analytical method was confirmed to be effective for aniline measurements of environmental water samples. Also, it is possible to conduct rapid analyses of aniline in environmental water without any solid-phase extraction process, compared to the solid-phase extraction-GC/MS method.

A new memetic algorithm for mitigating tandem automated guided vehicle system partitioning problem

NASA Astrophysics Data System (ADS)

Pourrahimian, Parinaz

2017-11-01

Automated Guided Vehicle System (AGVS) provides the flexibility and automation demanded by Flexible Manufacturing System (FMS). However, with the growing concern on responsible management of resource use, it is crucial to manage these vehicles in an efficient way in order reduces travel time and controls conflicts and congestions. This paper presents the development process of a new Memetic Algorithm (MA) for optimizing partitioning problem of tandem AGVS. MAs employ a Genetic Algorithm (GA), as a global search, and apply a local search to bring the solutions to a local optimum point. A new Tabu Search (TS) has been developed and combined with a GA to refine the newly generated individuals by GA. The aim of the proposed algorithm is to minimize the maximum workload of the system. After all, the performance of the proposed algorithm is evaluated using Matlab. This study also compared the objective function of the proposed MA with GA. The results showed that the TS, as a local search, significantly improves the objective function of the GA for different system sizes with large and small numbers of zone by 1.26 in average.

Copper-catalyzed tandem reactions of 1-(2-iodoary)-2-yn-1-ones with isocyanides for the synthesis of 4-oxo-indeno[1,2-b]pyrroles.

PubMed

Cai, Qian; Zhou, Fengtao; Xu, Tianfeng; Fu, Liangbing; Ding, Ke

2011-01-21

A novel copper-catalyzed tandem reaction of 1-(2-iodoaryl)-2-yn-1-ones with isocyanides is described. The reaction is through a formal [3 + 2] cycloaddition/coupling tandem process and leads to efficient formation of 4-oxo-indeno[1,2-b]pyrroles.

Optical limiting device and method of preparation thereof

DOEpatents

Wang, Hsing-Lin; Xu, Su; McBranch, Duncan W.

2003-01-01

Optical limiting device and method of preparation thereof. The optical limiting device includes a transparent substrate and at least one homogeneous layer of an RSA material in polyvinylbutyral attached to the substrate. The device may be produced by preparing a solution of an RSA material, preferably a metallophthalocyanine complex, and a solution of polyvinylbutyral, and then mixing the two solutions together to remove air bubbles. The resulting solution is layered onto the substrate and the solvent is evaporated. The method can be used to produce a dual tandem optical limiting device.

Modified tandem gratings anastigmatic imaging spectrometer with oblique incidence for spectral broadband

NASA Astrophysics Data System (ADS)

Cui, Chengguang; Wang, Shurong; Huang, Yu; Xue, Qingsheng; Li, Bo; Yu, Lei

2015-09-01

A modified spectrometer with tandem gratings that exhibits high spectral resolution and imaging quality for solar observation, monitoring, and understanding of coastal ocean processes is presented in this study. Spectral broadband anastigmatic imaging condition, spectral resolution, and initial optical structure are obtained based on geometric aberration theory. Compared with conventional tandem gratings spectrometers, this modified design permits flexibility in selecting gratings. A detailed discussion of the optical design and optical performance of an ultraviolet spectrometer with tandem gratings is also included to explain the advantage of oblique incidence for spectral broadband.

Monolithic Perovskite Silicon Tandem Solar Cells with Advanced Optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldschmidt, Jan C.; Bett, Alexander J.; Bivour, Martin

2016-11-14

For high efficiency monolithic perovskite silicon tandem solar cells, we develop low-temperature processes for the perovskite top cell, rear-side light trapping, optimized perovskite growth, transparent contacts and adapted characterization methods.

AlGaAs top solar cell for mechanical attachment in a multi-junction tandem concentrator solar cell stack

NASA Technical Reports Server (NTRS)

Dinetta, L. C.; Hannon, M. H.; Mcneely, J. B.; Barnett, A. M.

1991-01-01

The AstroPower self-supporting, transparent AlGaAs top solar cell can be stacked upon any well-developed bottom solar cell for improved system performance. This is an approach to improve the performance and scale of space photovoltaic power systems. Mechanically stacked tandem solar cell concentrator systems based on the AlGaAs top concentrator solar cell can provide near term efficiencies of 36 percent (AMO, 100x). Possible tandem stack efficiencies greater than 38 percent (100x, AMO) are feasible with a careful selection of materials. In a three solar cell stack, system efficiencies exceed 41 percent (100x, AMO). These device results demonstrate a practical solution for a state-of-the-art top solar cell for attachment to an existing, well-developed solar cell.

Hydrogen atom scrambling in selectively labeled anionic peptides upon collisional activation by MALDI tandem time-of-flight mass spectrometry.

PubMed

Bache, Nicolai; Rand, Kasper D; Roepstorff, Peter; Ploug, Michael; Jørgensen, Thomas J D

2008-12-01

We have previously shown that peptide amide hydrogens undergo extensive intramolecular migration (i.e., complete hydrogen scrambling) upon collisional activation of protonated peptides (Jørgensen et al. J. Am. Chem. Soc. 2005, 127, 2785-2793). The occurrence of hydrogen scrambling enforces severe limitations on the application of gas-phase fragmentation as a convenient method to obtain information about the site-specific deuterium uptake for proteins and peptides in solution. To investigate whether deprotonated peptides exhibit a lower level of scrambling relative to their protonated counterparts, we have now measured the level of hydrogen scrambling in a deprotonated, selectively labeled peptide using MALDI tandem time-of-flight mass spectrometry. Our results conclusively show that hydrogen scrambling is prevalent in the deprotonated peptide upon collisional activation. The amide hydrogens ((1)H/(2)H) have migrated extensively in the anionic peptide, thereby erasing the original regioselective deuteration pattern obtained in solution.

Detecting long tandem duplications in genomic sequences.

PubMed

Audemard, Eric; Schiex, Thomas; Faraut, Thomas

2012-05-08

Detecting duplication segments within completely sequenced genomes provides valuable information to address genome evolution and in particular the important question of the emergence of novel functions. The usual approach to gene duplication detection, based on all-pairs protein gene comparisons, provides only a restricted view of duplication. In this paper, we introduce ReD Tandem, a software using a flow based chaining algorithm targeted at detecting tandem duplication arrays of moderate to longer length regions, with possibly locally weak similarities, directly at the DNA level. On the A. thaliana genome, using a reference set of tandem duplicated genes built using TAIR,(a) we show that ReD Tandem is able to predict a large fraction of recently duplicated genes (dS  <  1) and that it is also able to predict tandem duplications involving non coding elements such as pseudo-genes or RNA genes. ReD Tandem allows to identify large tandem duplications without any annotation, leading to agnostic identification of tandem duplications. This approach nicely complements the usual protein gene based which ignores duplications involving non coding regions. It is however inherently restricted to relatively recent duplications. By recovering otherwise ignored events, ReD Tandem gives a more comprehensive view of existing evolutionary processes and may also allow to improve existing annotations.

A dye-sensitized photoelectrochemical tandem cell for light driven hydrogen production from water

DOE PAGES

Sherman, Benjamin D.; Sheridan, Matthew V.; Wee, Kyung -Ryang; ...

2016-12-02

Here, tandem junction photoelectrochemical water-splitting devices, whereby two light absorbing electrodes targeting separate portions of the solar spectrum generate the voltage required to convert water to oxygen and hydrogen, enable much higher possible efficiencies than single absorber systems. We report here on the development of a tandem system consisting of a dye-sensitized photoelectrochemical cell (DSPEC) wired in series with a dye-sensitized solar cell (DSC). The DSPEC photoanode incorporates a tris(bipyridine)ruthenium(II)-type chromophore and molecular ruthenium based water oxidation catalyst. The DSPEC was tested with two more-red absorbing DSC variations, one utilizing N719 dye with an I 3 –/I – redox mediatormore » solution and the other D35 dye with a tris(bipyridine)cobalt ([Co(bpy) 3] 3+/2+) based mediator. The tandem configuration consisting of the DSPEC and D35/[Co(bpy) 3] 3+/2+ based DSC gave the best overall performance and demonstrated the production of H 2 from H 2O with the only energy input from simulated solar illumination.« less

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

PubMed

Liu, Yunyun; Wan, Jie-Ping

2011-10-21

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.

TiAlN/TiAlON/Si{sub 3}N{sub 4} tandem absorber for high temperature solar selective applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barshilia, Harish C.; Selvakumar, N.; Rajam, K. S.

2006-11-06

A tandem absorber of TiAlN/TiAlON/Si{sub 3}N{sub 4} is prepared using a magnetron sputtering process. The graded composition of the individual component layers of the tandem absorber produces a film with a refractive index increasing from the surface to the substrate, which exhibits a high absorptance (0.95) and a low emittance (0.07). The tandem absorber is stable in air up to 600 deg. C for 2 h, indicating its importance for high temperature solar selective applications. The thermal stability of the tandem absorber is attributed to high oxidation resistance and microstructural stability of the component materials at higher temperatures.

High-Efficiency Polycrystalline Thin Film Tandem Solar Cells.

PubMed

Kranz, Lukas; Abate, Antonio; Feurer, Thomas; Fu, Fan; Avancini, Enrico; Löckinger, Johannes; Reinhard, Patrick; Zakeeruddin, Shaik M; Grätzel, Michael; Buecheler, Stephan; Tiwari, Ayodhya N

2015-07-16

A promising way to enhance the efficiency of CIGS solar cells is by combining them with perovskite solar cells in tandem devices. However, so far, such tandem devices had limited efficiency due to challenges in developing NIR-transparent perovskite top cells, which allow photons with energy below the perovskite band gap to be transmitted to the bottom cell. Here, a process for the fabrication of NIR-transparent perovskite solar cells is presented, which enables power conversion efficiencies up to 12.1% combined with an average sub-band gap transmission of 71% for photons with wavelength between 800 and 1000 nm. The combination of a NIR-transparent perovskite top cell with a CIGS bottom cell enabled a tandem device with 19.5% efficiency, which is the highest reported efficiency for a polycrystalline thin film tandem solar cell. Future developments of perovskite/CIGS tandem devices are discussed and prospects for devices with efficiency toward and above 27% are given.

Four-electron transfer tandem tetracyanoquinodimethane for cathode-active material in lithium secondary battery

NASA Astrophysics Data System (ADS)

Kurimoto, Naoya; Omoda, Ryo; Mizumo, Tomonobu; Ito, Seitaro; Aihara, Yuichi; Itoh, Takahito

2018-02-01

Quinoid compounds are important candidates of organic active materials for lithium-ion batteries. However, its high solubility to organic electrolyte solutions and low redox potential are known as their major drawbacks. To circumvent these issues, we have designed and synthesized a tandem-tetracyanoquinonedimethane type cathode-active material, 11,11,12,12,13,13,14,14-octacyano-1,4,5,8-anthradiquinotetramethane (OCNAQ), that has four redox sites per molecule, high redox potential and suppressed solubility to electrolyte solution. Synthesized OCNAQ has been found to have two-step redox reactions by cyclic voltammetry, and each step consists of two-electron reactions. During charge-discharge tests using selected organic cathode-active materials with a lithium metal anode, the cell voltages obtained from OCNAQ are higher than those for 11,11-dicyanoanthraquinone methide (AQM) as expected, due to the strong electron-withdrawing effect of the cyano groups. Unfortunately, even with the use of the organic active material, the issue of dissolution to the electrolyte solution cannot be suppressed completely; however, appropriate choice of the electrolyte solutions, glyme-based electrolyte solutions in this study, give considerable improvement of the cycle retention (98% and 56% at 10 and 100 cycles at 0.5C, respectively). The specific capacity and energy density obtained in this study are 206 mAh g-1 and 554 mWh g-1 with respect to the cathode active material.

Ca2+-stabilized adhesin helps an Antarctic bacterium reach out and bind ice.

PubMed

Vance, Tyler D R; Olijve, Luuk L C; Campbell, Robert L; Voets, Ilja K; Davies, Peter L; Guo, Shuaiqi

2014-07-04

The large size of a 1.5-MDa ice-binding adhesin [MpAFP (Marinomonas primoryensis antifreeze protein)] from an Antarctic Gram-negative bacterium, M. primoryensis, is mainly due to its highly repetitive RII (Region II). MpAFP_RII contains roughly 120 tandem copies of an identical 104-residue repeat. We have previously determined that a single RII repeat folds as a Ca2+-dependent immunoglobulin-like domain. Here, we solved the crystal structure of RII tetra-tandemer (four tandem RII repeats) to a resolution of 1.8 Å. The RII tetra-tandemer reveals an extended (~190-Å × ~25-Å), rod-like structure with four RII-repeats aligned in series with each other. The inter-repeat regions of the RII tetra-tandemer are strengthened by Ca2+ bound to acidic residues. SAXS (small-angle X-ray scattering) profiles indicate the RII tetra-tandemer is significantly rigidified upon Ca2+ binding, and that the protein's solution structure is in excellent agreement with its crystal structure. We hypothesize that >600 Ca2+ help rigidify the chain of ~120 104-residue repeats to form a ~0.6 μm rod-like structure in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed extender role of RII can help the strictly aerobic, motile bacterium bind ice in the upper reaches of the Antarctic lake where oxygen and nutrients are most abundant. Ca2+-induced rigidity of tandem Ig-like repeats in large adhesins might be a general mechanism used by bacteria to bind to their substrates and help colonize specific niches.

The Fundamental Flaws of Immunoassays and Potential Solutions Using Tandem Mass Spectrometry

PubMed Central

Hoofnagle, Andrew N.; Wener, Mark H.

2009-01-01

Immunoassays have made it possible to measure dozens of individual proteins and other analytes in human samples for help in establishing the diagnosis and prognosis of disease. In too many cases the results of those measurements are misleading and can lead to unnecessary treatment or missed opportunities for therapeutic interventions. These cases stem from problems inherent to immunoassays performed with human samples, which include a lack of concordance across platforms, autoantibodies, anti-reagent antibodies, and the high-dose hook effect. Tandem mass spectrometry may represent a detection method capable of alleviating many of the flaws inherent to immunoassays. We review our understanding of the problems associated with immunoassays on human specimens and describe methodologies using tandem mass spectrometry that could solve some of those problems. We also provide a critical discussion of the potential pitfalls of novel mass spectrometric approaches in the clinical laboratory. PMID:19538965

Multiple analyte adduct formation in liquid chromatography-tandem mass spectrometry - Advantages and limitations in the analysis of biologically-related samples.

PubMed

Dziadosz, Marek

2018-05-01

Multiple analyte adduct formation was examined and discussed in the context of reproducible signal detection in liquid chromatography-tandem mass spectrometry applied in the analysis of biologically-related samples. Appropriate infusion solutions were prepared in H 2 O/methanol (3/97, v/v) with 1 mM sodium acetate and 10 mM acetic acid. An API 4000 QTrap tandem mass spectrometer was used for experiments performed in the negative scan mode (-Q1 MS) and the negative enhanced product ion mode (-EPI). γ‑Hydroxybutyrate and its deuterated form were used as model compounds to highlight both the complexity of adduct formation in popular mobile phases used and the effective signal compensation by the application of isotope-labelled analytes as internal standards. Copyright © 2018 Elsevier B.V. All rights reserved.

Emergency Management Operations Process Mapping: Public Safety Technical Program Study

DTIC Science & Technology

2011-02-01

Enterprise Architectures in industry, and have been successfully applied to assist companies to optimise interdependencies and relationships between...model for more in-depth analysis of EM processes, and for use in tandem with other studies that apply modeling and simulation to assess EM...for use in tandem with other studies that apply modeling and simulation to assess EM operational effectiveness before and after changing elements

Base-promoted one-pot tandem reaction of 3-(1-alkynyl)chromones under microwave irradiation to functionalized amino-substituted xanthones.

PubMed

Liu, Yang; Huang, Liping; Xie, Fuchun; Hu, Youhong

2010-09-17

A base-promoted one-pot tandem reaction has been developed from 3-(1-alkynyl)chromones with various acetonitriles to afford functionalized amino-substituted xanthones 3 under microwave irradiation. This tandem process involves multiple reactions, such as Michael addition/cyclization/1,2-addition, without a transition metal catalyst. This method provides an efficient approach to build up natural product-like diversified amino-substituted xanthone scaffolds rapidly.

Automated processing of whole blood samples for the determination of immunosuppressants by liquid chromatography tandem-mass spectrometry.

PubMed

Vogeser, Michael; Spöhrer, Ute

2006-01-01

Liquid chromatography tandem-mass spectrometry (LC-MS/MS) is an efficient technology for routine determination of immunosuppressants in whole blood; however, time-consuming manual sample preparation remains a significant limitation of this technique. Using a commercially available robotic pipetting system (Tecan Freedom EVO), we developed an automated sample-preparation protocol for quantification of tacrolimus in whole blood by LC-MS/MS. Barcode reading, sample resuspension, transfer of whole blood aliquots into a deep-well plate, addition of internal standard solution, mixing, and protein precipitation by addition of an organic solvent is performed by the robotic system. After centrifugation of the plate, the deproteinized supernatants are submitted to on-line solid phase extraction, using column switching prior to LC-MS/MS analysis. The only manual actions within the entire process are decapping of the tubes, and transfer of the deep-well plate from the robotic system to a centrifuge and finally to the HPLC autosampler. Whole blood pools were used to assess the reproducibility of the entire analytical system for measuring tacrolimus concentrations. A total coefficient of variation of 1.7% was found for the entire automated analytical process (n=40; mean tacrolimus concentration, 5.3 microg/L). Close agreement between tacrolimus results obtained after manual and automated sample preparation was observed. The analytical system described here, comprising automated protein precipitation, on-line solid phase extraction and LC-MS/MS analysis, is convenient and precise, and minimizes hands-on time and the risk of mistakes in the quantification of whole blood immunosuppressant concentrations compared to conventional methods.

Low temperature perovskite solar cells with an evaporated TiO 2 compact layer for perovskite silicon tandem solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bett, Alexander J.; Schulze, Patricia S. C.; Winkler, Kristina

Silicon-based tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Perovskite solar cells are particularly promising as a top cell in monolithic tandem devices due to their rapid development towards high efficiencies, a tunable band gap with a sharp optical absorption edge and a simple production process. In monolithic tandem devices, the perovskite solar cell is deposited directly on the silicon cell, requiring low-temperature processes (< 200 °C) to maintain functionality of under-lying layers of the silicon cell in case of highly efficient silicon hetero-junction (SHJ) bottom solar cell. In this work, we present amore » complete low-temperature process for perovskite solar cells including a mesoporous titanium oxide (TiO 2) scaffold - a structure yielding the highest efficiencies for single-junction perovskite solar cells. We show that evaporation of the compact TiO 2 hole blocking layer and ultra-violet (UV) curing for the mesoporous TiO 2 layer allows for good performance, comparable to high-temperature (> 500 °C) processes. With both manufacturing routes, we obtain short-circuit current densities (J SC) of about 20 mA/cm 2, open-circuit voltages (V OC) over 1 V, fill factors (FF) between 0.7 and 0.8 and efficiencies (n) of more than 15%. We further show that the evaporated TiO 2 layer is suitable for the application in tandem devices. The series resistance of the layer itself and the contact resistance to an indium doped tin oxide (ITO) interconnection layer between the two sub-cells are low. Additionally, the low parasitic absorption for wavelengths above the perovskite band gap allow a higher absorption in the silicon bottom solar cell, which is essential to achieve high tandem efficiencies.« less

Low temperature perovskite solar cells with an evaporated TiO 2 compact layer for perovskite silicon tandem solar cells

DOE PAGES

Bett, Alexander J.; Schulze, Patricia S. C.; Winkler, Kristina; ...

2017-09-21

Silicon-based tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Perovskite solar cells are particularly promising as a top cell in monolithic tandem devices due to their rapid development towards high efficiencies, a tunable band gap with a sharp optical absorption edge and a simple production process. In monolithic tandem devices, the perovskite solar cell is deposited directly on the silicon cell, requiring low-temperature processes (< 200 °C) to maintain functionality of under-lying layers of the silicon cell in case of highly efficient silicon hetero-junction (SHJ) bottom solar cell. In this work, we present amore » complete low-temperature process for perovskite solar cells including a mesoporous titanium oxide (TiO 2) scaffold - a structure yielding the highest efficiencies for single-junction perovskite solar cells. We show that evaporation of the compact TiO 2 hole blocking layer and ultra-violet (UV) curing for the mesoporous TiO 2 layer allows for good performance, comparable to high-temperature (> 500 °C) processes. With both manufacturing routes, we obtain short-circuit current densities (J SC) of about 20 mA/cm 2, open-circuit voltages (V OC) over 1 V, fill factors (FF) between 0.7 and 0.8 and efficiencies (n) of more than 15%. We further show that the evaporated TiO 2 layer is suitable for the application in tandem devices. The series resistance of the layer itself and the contact resistance to an indium doped tin oxide (ITO) interconnection layer between the two sub-cells are low. Additionally, the low parasitic absorption for wavelengths above the perovskite band gap allow a higher absorption in the silicon bottom solar cell, which is essential to achieve high tandem efficiencies.« less

[Determination of biurea in flour and its products by liquid chromatography-tandem mass spectrometry].

PubMed

Wang, Ya; Wang, Junsu; Xiang, Lu; Xi, Cunxian; Chen, Dongdong; Peng, Tao; Wang, Guomin; Mu, Zhaode

2014-05-01

A novel method was established for the determination and identification of biurea in flour and its products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biurea was extracted with water and oxidized to azodicarbonamide by potassium permanganate. The azodicarbonamide was then derivatized using sodium p-toluene sulfinate solution. The separation was performed on a Shimpak XR-ODS II column (150 mm x 2.0 mm, 2.2 microm) using the mobile phase composed of acetonitrile and 2 mmol/L ammonium acetate aqueous solution (containing 0.2% (v/v) formic acid) with a gradient elution program. Tandem mass spectrometric detection was performed in multiple reaction monitoring (MRM) scan mode with a positive electrospray ionization (ESI(+)) source. The method used stable isotope internal standard quantitation. The calibration curve showed good linearity over the range of 1-20 000 microg/kg (R2 = 0.999 9). The limit of quantification was 5 microg/kg for biurea spiked in flour and its products. At the spiking levels of 5.0, 10.0 and 50.0 microg/kg in different matrices, the average recovery o biurea was 78.3%-108.0% with the relative standard deviations (RSDs) < or = 5.73%. The method developed is novel, reliable and sensitive with wide linear range, and can be used to determine the biurea in flour and its products.

[Liquid chromatography-tandem mass spectrometry method for determination of 10 macrolide antibiotics in pork samples using on-line solid phase extraction purification].

PubMed

Zhang, Xiaoguang; Liu, Dong; Liu, Hongran; Li, Qiang; Li, Lili; Wang, Lixia; Zhang, Yan

2017-10-08

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method based on-line solid phase extraction (SPE) purification was established to determine 10 macrolide antibiotics in pork samples. The samples were extracted with acetonitrile, and the extracts were dried with rotary evaporator at 40℃, then the analytes were dissolved with 2 mL phosphate buffer. The solutions were purified and concentrated by on-line SPE with HLB cartridges. The analytes were eluted with methanol, and then transferred to XBridge BEH C18 column, separated with the mobile phases of 10 mmol/L ammonium acetate aqueous solution and acetonitrile. Finally, the target analytes were detected by tandem mass spectrometry. The results showed that good linearity was obtained in the range of 0.1-200 μg/L for the 10 macrolide antibiotics with correlation coefficients better than 0.990. The limits of detection were in range of 0.05-0.30 μg/kg and the limits of quantitation were in range of 0.10-1.00 μg/kg. The recoveries of the method were in range of 69.6%-115.2% at the spiked levels of 0.10-10.0 μg/kg for all analytes, with the relative standard deviations less than 10%. The developed method can be used for the determination of the 10 macrolide antibiotics in pork samples.

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

NASA Astrophysics Data System (ADS)

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

2014-10-01

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.

Investigation of absolute and relative response for three different liquid chromatography/tandem mass spectrometry systems; the impact of ionization and detection saturation.

PubMed

Nilsson, Lars B; Skansen, Patrik

2012-06-30

The investigations in this article were triggered by two observations in the laboratory; for some liquid chromatography/tandem mass spectrometry (LC/MS/MS) systems it was possible to obtain linear calibration curves for extreme concentration ranges and for some systems seemingly linear calibration curves gave good accuracy at low concentrations only when using a quadratic regression function. The absolute and relative responses were tested for three different LC/MS/MS systems by injecting solutions of a model compound and a stable isotope labeled internal standard. The analyte concentration range for the solutions was 0.00391 to 500 μM (128,000×), giving overload of the chromatographic column at the highest concentrations. The stable isotope labeled internal standard concentration was 0.667 μM in all samples. The absolute response per concentration unit decreased rapidly as higher concentrations were injected. The relative response, the ratio for the analyte peak area to the internal standard peak area, per concentration unit was calculated. For system 1, the ionization process was found to limit the response and the relative response per concentration unit was constant. For systems 2 and 3, the ion detection process was the limiting factor resulting in decreasing relative response at increasing concentrations. For systems behaving like system 1, simple linear regression can be used for any concentration range while, for systems behaving like systems 2 and 3, non-linear regression is recommended for all concentration ranges. Another consequence is that the ionization capacity limited systems will be insensitive to matrix ion suppression when an ideal internal standard is used while the detection capacity limited systems are at risk of giving erroneous results at high concentrations if the matrix ion suppression varies for different samples in a run. Copyright © 2012 John Wiley & Sons, Ltd.

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

NASA Astrophysics Data System (ADS)

Green, Martin A.

2014-03-01

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.

Electrospray-assisted laser desorption/ionization and tandem mass spectrometry of peptides and proteins.

PubMed

Peng, Ivory X; Shiea, Jentaie; Ogorzalek Loo, Rachel R; Loo, Joseph A

2007-01-01

We have constructed an electrospray-assisted laser desorption/ionization (ELDI) source which utilizes a nitrogen laser pulse to desorb intact molecules from matrix-containing sample solution droplets, followed by electrospray ionization (ESI) post-ionization. The ELDI source is coupled to a quadrupole ion trap mass spectrometer and allows sampling under ambient conditions. Preliminary data showed that ELDI produces ESI-like multiply charged peptides and proteins up to 29 kDa carbonic anhydrase and 66 kDa bovine albumin from single-protein solutions, as well as from complex digest mixtures. The generated multiply charged polypeptides enable efficient tandem mass spectrometric (MS/MS)-based peptide sequencing. ELDI-MS/MS of protein digests and small intact proteins was performed both by collisionally activated dissociation (CAD) and by nozzle-skimmer dissociation (NSD). ELDI-MS/MS may be a useful tool for protein sequencing analysis and top-down proteomics study, and may complement matrix-assisted laser desorption/ionization (MALDI)-based measurements. Copyright (c) 2007 John Wiley & Sons, Ltd.

Catalytic asymmetric epoxidation of alpha,beta-unsaturated amides: efficient synthesis of beta-aryl alpha-hydroxy amides using a one-pot tandem catalytic asymmetric epoxidation-Pd-catalyzed epoxide opening process.

PubMed

Nemoto, Tetsuhiro; Kakei, Hiroyuki; Gnanadesikan, Vijay; Tosaki, Shin-Ya; Ohshima, Takashi; Shibasaki, Masakatsu

2002-12-11

The catalytic asymmetric epoxidation of alpha,beta-unsaturated amides using Sm-BINOL-Ph3As=O complex was succeeded. Using 5-10 mol % of the asymmetric catalyst, a variety of amides were epoxidized efficiently, yielding the corresponding alpha,beta-epoxy amides in up to 99% yield and in more than 99% ee. Moreover, the novel one-pot tandem process, one-pot tandem catalytic asymmetric epoxidation-Pd-catalyzed epoxide opening process, was developed. This method was successfully utilized for the efficient synthesis of beta-aryl alpha-hydroxy amides, including beta-aryllactyl-leucine methyl esters. Interestingly, it was found that beneficial modifications on the Pd catalyst were achieved by the constituents of the first epoxidation, producing a more suitable catalyst for the Pd-catalyzed epoxide opening reaction in terms of chemoselectivity.

If the cap fits, wear it: an overview of telomeric structures over evolution.

PubMed

Fulcher, Nick; Derboven, Elisa; Valuchova, Sona; Riha, Karel

2014-03-01

Genome organization into linear chromosomes likely represents an important evolutionary innovation that has permitted the development of the sexual life cycle; this process has consequently advanced nuclear expansion and increased complexity of eukaryotic genomes. Chromosome linearity, however, poses a major challenge to the internal cellular machinery. The need to efficiently recognize and repair DNA double-strand breaks that occur as a consequence of DNA damage presents a constant threat to native chromosome ends known as telomeres. In this review, we present a comparative survey of various solutions to the end protection problem, maintaining an emphasis on DNA structure. This begins with telomeric structures derived from a subset of prokaryotes, mitochondria, and viruses, and will progress into the typical telomere structure exhibited by higher organisms containing TTAGG-like tandem sequences. We next examine non-canonical telomeres from Drosophila melanogaster, which comprise arrays of retrotransposons. Finally, we discuss telomeric structures in evolution and possible switches between canonical and non-canonical solutions to chromosome end protection.

Determination of moxifloxacin and its oxidation products with kinetic evaluation under potassium permanganate treatment in acidic solution by ultra-performance liquid chromatography/tandem mass spectrometry.

PubMed

Hubicka, Urszula; Zmudzki, Paweł; Zajdel, Paweł; Krzek, Jan

2013-01-01

A simple, sensitive, and reproducible ultra-performance LC method for the determination of moxifloxacin (MOXI) oxidation stability under permanganate treatment in acidic conditions (pH 3.0-6.0) was developed. Besides the MOXI peak [retention time (RT) = 2.58], four additional products (RT = 0.86, 0.91, 1.42, and 1.89) were observed in all conditions tested. The oxidation process followed second-order reaction kinetics and depended upon solution acidity. The highest reaction rate constant was observed at pH 3.0, and this value decreased as the pH was increased to 6.0. The oxidation products were characterized, and their fragmentation pathways, derived from MS/MS data, were proposed. Two of these products were identified as hydroxyl derivatives of MOXI and two others as their oxidation product analogs with molecular ions of 418.4 and 416.4 m/z, respectively.

Improve definition of titanium tandems in MR-guided high dose rate brachytherapy for cervical cancer using proton density weighted MRI

PubMed Central

2013-01-01

Background For cervical cancer patients treated with MR-guided high dose rate brachytherapy, the accuracy of radiation delivery depends on accurate localization of both tumors and the applicator, e.g. tandem and ovoid. Standard T2-weighted (T2W) MRI has good tumor-tissue contrast. However, it suffers from poor uterus-tandem contrast, which makes the tandem delineation very challenging. In this study, we evaluated the possibility of using proton density weighted (PDW) MRI to improve the definition of titanium tandems. Methods Both T2W and PDW MRI images were obtained from each cervical cancer patient. Imaging parameters were kept the same between the T2W and PDW sequences for each patient except the echo time (90 ms for T2W and 5.5 ms for PDW) and the slice thickness (0.5 cm for T2W and 0.25 cm for PDW). Uterus-tandem contrast was calculated by the equation C = (Su-St)/Su, where Su and St represented the average signal in the uterus and the tandem, respectively. The diameter of the tandem was measured 1.5 cm away from the tip of the tandem. The tandem was segmented by the histogram thresholding technique. Results PDW MRI could significantly improve the uterus-tandem contrast compared to T2W MRI (0.42±0.24 for T2W MRI, 0.77±0.14 for PDW MRI, p=0.0002). The average difference between the measured and physical diameters of the tandem was reduced from 0.20±0.15 cm by using T2W MRI to 0.10±0.11 cm by using PDW MRI (p=0.0003). The tandem segmented from the PDW image looked more uniform and complete compared to that from the T2W image. Conclusions Compared to the standard T2W MRI, PDW MRI has better uterus-tandem contrast. The information provided by PDW MRI is complementary to those provided by T2W MRI. Therefore, we recommend adding PDW MRI to the simulation protocol to assist tandem delineation process for cervical cancer patients. PMID:23327682

Extraction and Liquid Chromatography-Tandem Mass Spectrometry Detection of 3-Monochloropropanediol Esters and Glycidyl Esters in Infant Formula.

PubMed

Leigh, Jessica K; MacMahon, Shaun

2016-12-14

A method was developed for the extraction of fatty acid esters of 3-chloro-1,2-propanediol (3-MCPD) and glycidol from infant formula, followed by quantitative analysis of the extracts using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These process-induced chemical contaminants are found in refined vegetable oils, and studies have shown that they are potentially carcinogenic and/or genotoxic, making their presence in edible oils (and processed foods containing these oils) a potential health risk. The extraction procedure involves a liquid-liquid extraction, where powdered infant formula is dissolved in water and extracted with ethyl acetate. Following shaking, centrifugation, and drying of the organic phase, the resulting fat extract is cleaned-up using solid-phase extraction and analyzed by LC-MS/MS. Method performance was confirmed by verifying the percent recovery of each 3-MCPD and glycidyl ester in a homemade powdered infant formula reference material. Average ester recoveries in the reference material ranged from 84.9 to 109.0% (0.6-9.5% RSD). The method was also validated by fortifying three varieties of commercial infant formulas with a 3-MCPD and glycidyl ester solution. Average recoveries of the esters across all concentrations and varieties of infant formula ranged from 88.7 to 107.5% (1.0-9.5% RSD). Based on the validation results, this method is suitable for producing 3-MCPD and glycidyl ester occurrence data in all commercially available varieties of infant formula.

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

PubMed Central

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

1986-01-01

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

A Lossy Compression Technique Enabling Duplication-Aware Sequence Alignment

PubMed Central

Freschi, Valerio; Bogliolo, Alessandro

2012-01-01

In spite of the recognized importance of tandem duplications in genome evolution, commonly adopted sequence comparison algorithms do not take into account complex mutation events involving more than one residue at the time, since they are not compliant with the underlying assumption of statistical independence of adjacent residues. As a consequence, the presence of tandem repeats in sequences under comparison may impair the biological significance of the resulting alignment. Although solutions have been proposed, repeat-aware sequence alignment is still considered to be an open problem and new efficient and effective methods have been advocated. The present paper describes an alternative lossy compression scheme for genomic sequences which iteratively collapses repeats of increasing length. The resulting approximate representations do not contain tandem duplications, while retaining enough information for making their comparison even more significant than the edit distance between the original sequences. This allows us to exploit traditional alignment algorithms directly on the compressed sequences. Results confirm the validity of the proposed approach for the problem of duplication-aware sequence alignment. PMID:22518086

Highly efficient tandem organic light-emitting devices employing an easily fabricated charge generation unit

NASA Astrophysics Data System (ADS)

Yang, Huishan; Yu, Yaoyao; Wu, Lishuang; Qu, Biao; Lin, Wenyan; Yu, Ye; Wu, Zhijun; Xie, Wenfa

2018-02-01

We have realized highly efficient tandem organic light-emitting devices (OLEDs) employing an easily fabricated charge generation unit (CGU) combining 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile with ultrathin bilayers of CsN3 and Al. The charge generation and separation processes of the CGU have been demonstrated by studying the differences in the current density-voltage characteristics of external-carrier-excluding devices. At high luminances of 1000 and 10000 cd/m2, the current efficiencies of the phosphorescent tandem device are about 2.2- and 2.3-fold those of the corresponding single-unit device, respectively. Simultaneously, an efficient tandem white OLED exhibiting high color stability and warm white emission has also been fabricated.

Highly efficient conversion of terpenoid biomass to jet-fuel range cycloalkanes in a biphasic tandem catalytic process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaokun; Li, Teng; Tang, Kan

2017-06-12

The demand for bio-jet fuels to reduce carbon emissions is increasing substantially in the aviation sector, while the scarcity of high-density jet fuel components limits the use of bio-jet fuels in high-performance aircrafts compared with conventional jet fuels. In this paper, we report a novel biphasic tandem catalytic process (biTCP) for synthesizing cycloalkanes from renewable terpenoid biomass, such as 1,8-cineole. Multistep tandem reactions, including C–O ring opening by hydrolysis, dehydration, and hydrogenation, were carried out in the “one-pot” biTCP. 1,8-Cineole was efficiently converted to p-menthane at high yields (>99%) in the biTCP under mild reaction conditions. Finally, the catalytic reactionmore » mechanism is discussed.« less

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

NASA Technical Reports Server (NTRS)

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

2005-01-01

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

Use of electrospray ionization ion-trap tandem mass spectrometry and principal component analysis to directly distinguish monosaccharides.

PubMed

Xia, Bing; Zhou, Yan; Liu, Xin; Xiao, Juan; Liu, Qing; Gu, Yucheng; Ding, Lisheng

2012-06-15

Carbohydrates are good source of drugs and play important roles in metabolism processes and cellular interactions in organisms. Distinguishing monosaccharide isomers in saccharide derivates is an important and elementary work in investigating saccharides. It is important to develop a fast, simple and direct method for this purpose, which is described in this study. Stock solutions of monosaccharide with a concentration of 400 μM and sodium chloride at a concentration of 10 μM were made in water/methanol (50:50, v/v). The samples were subjected to electrospray ionization ion-trap tandem mass spectrometry (ESI-MS) and the detected [2M + Na - H(2)O](+) ions were further investigated by tandem mass spectrometry (MS/MS), followed by applying principal component analysis (PCA) on the obtained MS/MS data sets. The MS/MS spectra of the [2M + Na - H(2)O](+) ions at m/z 365 for hexoses and m/z 305 for pentoses yielded unambiguous fragment patterns, while rhamnose can be directly identified by its ESI-MS [M + Na](+) ion at m/z 187. PCA showed clustering of MS/MS data of identical monosaccharide samples obtained from different experiments. By using this method, the monosaccharide in daucosterol hydrolysate was successfully identified. A new strategy was developed for differentiation of the monosaccharides using ESI-MS/MS and PCA. In MS/MS spectra, the [2M + Na - H(2)O](+) ions yielded unambiguous distinction. PCA of the archived MS/MS data sets was applied to demonstrate the spatial resolution of the studied samples. This method presented a simple and reliable way for distinguishing monosaccharides by ESI-MS/MS. Copyright © 2012 John Wiley & Sons, Ltd.

Tungsten-188/carrier-free rhenium-188 perrhenic acid generator system

DOEpatents

Knapp, Jr., Furn F.; Lisic, Edward C.; Mirzadeh, Saed; Callahan, Alvin P.

1993-01-01

A generator system for providing a carrier-free radioisotope in the form of an acid comprises a chromatography column in tandem fluid connection with an ion exchange column, the chromatography column containing a charge of a radioactive parent isotope. The chromatography column, charged with a parent isotope, is eluted with an alkali metal salt solution to generate the radioisotope in the form of an intermediate solution, which is passed through the ion-exchange column to convert the radioisotope to a carrier-free acid form.

Tungsten-188/carrier-free rhenium-188 perrhenic acid generator system

DOEpatents

Knapp, F.F. Jr.; Lisic, E.C.; Mirzadeh, S.; Callahan, A.P.

1993-02-16

A generator system for providing a carrier-free radioisotope in the form of an acid comprises a chromatography column in tandem fluid connection with an ion exchange column, the chromatography column containing a charge of a radioactive parent isotope. The chromatography column, charged with a parent isotope, is eluted with an alkali metal salt solution to generate the radioisotope in the form of an intermediate solution, which is passed through the ion-exchange column to convert the radioisotope to a carrier-free acid form.

Tungsten-188/carrier-free rhenium-188 perrhenic acid generator system

DOEpatents

Knapp, Jr., Furn F.; Lisic, Edward C.; Mirzadeh, Saed; Callahan, Alvin P.

1994-01-01

A generator system for providing a carrier-free radioisotope in the form of an acid comprises a chromatography column in tandem fluid connection with an ion exchange column, the chromatography column containing a charge of a radioactive parent isotope. The chromatography column, charged with a parent isotope, is eluted with an alkali metal salt solution to generate the radioisotope in the form of an intermediate solution, which is passed through the ion-exchange column to convert the radioisotope to a carrier-free acid form.

Exploring the repeat protein universe through computational protein design

DOE PAGES

Brunette, TJ; Parmeggiani, Fabio; Huang, Po-Ssu; ...

2015-12-16

A central question in protein evolution is the extent to which naturally occurring proteins sample the space of folded structures accessible to the polypeptide chain. Repeat proteins composed of multiple tandem copies of a modular structure unit are widespread in nature and have critical roles in molecular recognition, signalling, and other essential biological processes. Naturally occurring repeat proteins have been re-engineered for molecular recognition and modular scaffolding applications. In this paper, we use computational protein design to investigate the space of folded structures that can be generated by tandem repeating a simple helix–loop–helix–loop structural motif. Eighty-three designs with sequences unrelatedmore » to known repeat proteins were experimentally characterized. Of these, 53 are monomeric and stable at 95 °C, and 43 have solution X-ray scattering spectra consistent with the design models. Crystal structures of 15 designs spanning a broad range of curvatures are in close agreement with the design models with root mean square deviations ranging from 0.7 to 2.5 Å. Finally, our results show that existing repeat proteins occupy only a small fraction of the possible repeat protein sequence and structure space and that it is possible to design novel repeat proteins with precisely specified geometries, opening up a wide array of new possibilities for biomolecular engineering.« less

Configural displays can improve nutrition-related. decisions: an application of the proximity compatibility principle.

PubMed

Marino, Christopher J; Mahan, Robert R

2005-01-01

The nutrition label format currently used by consumers to make dietary-related decisions presents significant information-processing demands for integration-based decisions; however, those demands were not considered as primary factors when the format was adopted. Labels designed in accordance with known principles of cognitive psychology might enhance the kind of decision making that food labeling was intended to facilitate. Three experiments were designed on the basis of the proximity compatibility principle (PCP) to investigate the relationship between nutrition label format and decision making; the experiments involved two types of integration decisions and one type of filtering decision. Based on the PCP, decision performance was measured to test the overall hypothesis that matched task-display tandems would result in better decision performance than would mismatched tandems. In each experiment, a statistically significant increase in mean decision performance was found when the display design was cognitively matched to the demands of the task. Combined, the results from all three experiments support the general hypothesis that task-display matching is a design principle that may enhance the utility of nutrition labeling in nutrition-related decision making. Actual or potential applications of this research include developing robust display solutions that aid in less effortful assimilation of nutrition-related information for consumers.

Quantitative Analysis for Installation Access Planning at Naval Base San Diego

DTIC Science & Technology

2012-09-01

VPH in one processing lane, then we can assume that if the SECO were to open another sentry processing lane, the total throughput of both lanes would...be 600 VPH . Similarly, if two sentries in tandem can produce a throughput of 500 VPH , then having two lanes with two sentries in tandem each will...produce a total throughput of 1000 VPH . We assume throughout that there is no server idleness and so there is essentially an infinite backlog of

Synfuels from fusion: using the tandem mirror reactor and a thermochemical cycle to produce hydrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werner, R.W.

1982-11-01

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)

A novel automated hydrophilic interaction liquid chromatography method using diode-array detector/electrospray ionization tandem mass spectrometry for analysis of sodium risedronate and related degradation products in pharmaceuticals.

PubMed

Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

2014-10-24

A simple, sensitive and fast hydrophilic interaction liquid chromatography (HILIC) method using ultraviolet diode-array detector (UV-DAD)/electrospray ionization tandem mass spectrometry was developed for the automated high performance liquid chromatography (HPLC) determination of sodium risedronate (SR) and its degradation products in new pharmaceuticals. The chromatographic separations were performed on Ascentis Express HILIC 2.7μm (150mm×2.1mm, i.d.) stainless steel column (fused core). The mobile phase consisted of formate buffer solution (pH 3.4; 0.03M)/acetonitrile 42:58 and 45:55 (v/v) for granules for oral solution and effervescent tablet analysis, respectively, at a flow-rate of 0.2mL/min, setting the wavelength at 262nm. Stability characteristics of SR were evaluated by performing stress test studies. The main degradation product formed under oxidation conditions corresponding to sodium hydrogen (1-hydroxy-2-(1-oxidopyridin-3-yl)-1-phosphonoethyl)phosphonate was characterized by high performance liquid chromatography-electrospray ionization-mass tandem mass spectrometry (HPLC-ESI-MS/MS). The validation parameters such as linearity, sensitivity, accuracy, precision and selectivity were found to be highly satisfactory. Linear responses were observed in standard and in fortified placebo solutions. Intra-day precision (relative standard deviation, RSD) was ≤1.1% for peak area and ≤0.2% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 98.7 to 101.0%) with RSD ranging from 0.6 to 0.7%. The limits of detection (LOD) and quantitation (LOQ) were 1 and 3ng/mL, respectively. The high stability of standard and sample solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed stability indicating method is suitable for the quality control of SR in new and commercial pharmaceutical formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Autonomous Metabolomics for Rapid Metabolite Identification in Global Profiling

DOE PAGES

Benton, H. Paul; Ivanisevic, Julijana; Mahieu, Nathaniel G.; ...

2014-12-12

An autonomous metabolomic workflow combining mass spectrometry analysis with tandem mass spectrometry data acquisition was designed to allow for simultaneous data processing and metabolite characterization. Although previously tandem mass spectrometry data have been generated on the fly, the experiments described herein combine this technology with the bioinformatic resources of XCMS and METLIN. We can analyze large profiling datasets and simultaneously obtain structural identifications, as a result of this unique integration. Furthermore, validation of the workflow on bacterial samples allowed the profiling on the order of a thousand metabolite features with simultaneous tandem mass spectra data acquisition. The tandem mass spectrometrymore » data acquisition enabled automatic search and matching against the METLIN tandem mass spectrometry database, shortening the current workflow from days to hours. Overall, the autonomous approach to untargeted metabolomics provides an efficient means of metabolomic profiling, and will ultimately allow the more rapid integration of comparative analyses, metabolite identification, and data analysis at a systems biology level.« less

[Measurement of free urinary cortisol and cortisone using liquid chromatography associated with tandem mass spectrometry method].

PubMed

Vieira, José Gilberto H; Nakamura, Odete H; Carvalho, Valdemir M

2005-04-01

Free urinary cortisol (UFF) measurement is one of the most useful screening tests for Cushing's syndrome. Immunoassays employed today by most clinical laboratories present limitations, specially concerning specificity. These limitations restrain a widespread application of the method, as well as the comparison of results obtained by the use of different methods. We present the development and characterization of a UFF and cortisone method based on liquid chromatography and tandem mass spectrometry (LC-MS/MS). A 200 microL aliquot from a 24 h urine sample is mixed with a solution containing a known quantity of deuterated cortisol and on-line extracted in solid phase (C18). The eluate is transferred to a second C18 column (Phenomenex Luna, 3 micro, 50 x 2 mm) and the isocratic mode elution profile is directly applied to a tandem mass spectrometer model Quattro Micro operating in positive mode atmospheric pressure chemical ionization (APCI). All process is automated and the quantification is performed by isotopic dilution, based on the analyte and the deuterated internal standard peak area ratios. The specificity study showed that all the steroids tested presented cross reactivity of <1% for cortisol and cortisone. Functional sensitivity is <1 microg/L for both steroids, and the interassay CV <8%. Recovery and linearity studies were satisfactory and comparison of results obtained using a RIA for UFF and the present method in 98 routine samples showed a correlation of r= 0.838, with the results obtained with LC-MS/MS significantly lower (medians of 22.0 vs. 49.4 microg/24 h for RIA) (P<0.0001). Reference values for cortisol were defined as values between 11 and 43 microg/24 h, compatible to those recently described for similar methods. The concomitant measurement of UF cortisone allows the study of the activity of the enzyme 11beta-HSD2 and the diagnosis of the apparent mineralocorticoid excess syndrome. The method represents the first steroid assay of a new generation, based on automated preparative methods and tandem mass spectrometry, described in our country.

Aerodynamic Characteristics of Tube-Launched Tandem Wing Unmanned Aerial Vehicle

NASA Astrophysics Data System (ADS)

Rosid, Nurhayyan H.; Irsyad Lukman, E.; Fadlillah, M. Ahmad; Agoes Moelyadi, M.

2018-04-01

Tube Launched UAV with expandable tandem-wing configuration becomes one of the most interesting topic to be investigated. Folding wing mechanism is used due to the requirements that the UAV should be folded into tubular launcher. This paper focuses on investigating the aerodynamics characteristics because of the effects of folding wing mechanism, tandem wing configuration, and rapid deploying process from tube launcher. The aerodynamic characteristics investigation is conducted using computational fluid dynamics (CFD) at low Reynolds numbers (Re < 200000). The results of the simulation are used for the development of ITB Tube-launched UAV prototype and for future studies.

Thermodynamically Leveraged Tandem Catalysis for Ester RC(O)O–R' Bond Hydrogenolysis. Scope and Mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lohr, Tracy L.; Li, Zhi; Assary, Rajeev S.

2015-05-18

Rapid and selective formal hydrogenolysis of aliphatic ester RC(O)O–R' linkages is achieved by a tandem homogeneous metal triflate + supported palladium catalytic system. The triflate catalyzes the mildly exothermic, turnover-limiting O–R' cleavage process, whereas the exothermic hydrogenation of the intermediate alkene further drives the overall reaction to completion.

Thermodynamically leveraged Tandem catalysis for ester RC(O)O-R' bond hydrogenolysis. scope and mechanism.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lohr, Tracy L.; Li, Zhi; Assary, Rajeev S.

2015-06-01

Rapid and selective formal hydrogenolysis of aliphatic ester RC(O)O-R' linkages is achieved by a tandem homogeneous metal triflate + supported palladium catalytic system. The triflate catalyzes the mildly exothermic, turnover-limiting O-R' cleavage process, whereas the exothermic hydrogenation of the intermediate alkene further drives the overall reaction to completion.

Solution and solid trinitrotoluene (TNT) photochemistry: persistence of TNT-like ultraviolet (UV) resonance Raman bands.

PubMed

Gares, Katie L; Bykov, Sergei V; Godugu, Bhaskar; Asher, Sanford A

2014-01-01

We examined the 229 nm deep-ultraviolet resonance Raman (DUVRR) spectra of solution and solid-state trinitrotoluene (TNT) and its solution and solid-state photochemistry. Although TNT photodegrades with a solution quantum yield of ϕ ∼ 0.015, the initial photoproducts show DUVRR spectra extraordinarily similar to pure TNT, due to the similar photoproduct enhancement of the -NO2 stretching vibrations. This results in TNT-like DUVRR spectra even after complete TNT photolysis. These ultraviolet resonance Raman spectral bands enable DUVRR of trace as well as DUVRR standoff TNT detection. We determined the structure of various initial TNT photoproducts by using liquid chromatography-mass spectrometry and tandem mass spectrometry. Similar TNT DUVRR spectra and photoproducts are observed in the solution and solid states.

Online Learning and Performance Support in Organizational Environments Using Performance Support Platforms

ERIC Educational Resources Information Center

Gal, Eran; Nachmias, Rafi

2011-01-01

An electronic performance support system (EPSS) is a method that integrates learning and task performance into one single action by providing information and guidance during performance. Wide-range EPSS effectiveness research has been conducted by Tel Aviv University in tandem with a large telecommunications firm implementing EPSS solutions. The…

Validation of a confirmatory method for the determination of residues of four nitrofurans in egg by liquid chromatography-tandem mass spectrometry with the software InterVal.

PubMed

Bock, C; Stachel, C; Gowik, P

2007-03-14

A method for the detection and determination of nitrofuran derivatives in egg by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated with the software InterVal and can be applied for the confirmation of nitrofuran metabolites in fresh or lyophilised eggs. The validation study comprises variations in operator, storage condition, breeding, equipment and duration of sample preparation. A comprehensive overview of the robustness of the method is obtained by analysing eight samples at six concentration levels. First results of short- and medium-term investigations for stability of analytes in solution show that standard solutions of nitrofuran metabolites are stable for at least 1 year when stored at +4 degrees C in the dark. The decision limit CCalpha expressed for the underivatised metabolite is 0.05 microg kg(-1) for 3-amino-5-methyl-morpholino-2-oxazolidinone, 0.03 microg kg(-1) for 3-amino-2-oxazolidinone, 0.20 microg kg(-1) for semicarbazide and 0.22 microg kg(-1) for 1-amino-hydantoin.

Improvement of the performances of a tandem simulated moving bed chromatography by controlling the yield level of a key product of the first simulated moving bed unit.

PubMed

Mun, Sungyong; Wang, Nien-Hwa Linda

2017-03-10

One of the trustworthy processes for ternary separation is a tandem simulated moving bed (SMB) process, which consists of two subordinate four-zone SMB units (Ring I and Ring II). To take full advantage of a tandem SMB as a means of recovering all three products with high purities and high economical efficiency, it is important to understand how the separation condition in Ring II is affected by that in Ring I, and further to reflect such point in the stage of designing a tandem SMB. In regard to such issue, it was clarified in this study that the Ring I factors affecting the Ring II condition could be represented by the yield level of a key product of Ring I (Y key RingI ). As the Y key RingI level became higher, the amount of the Ring I key-product that was reloaded into Ring II was reduced, which affected favorably the Ring II separation condition. On the other hand, the higher Y key RingI level caused a larger dilution for the stream from Ring I to Ring II, which affected adversely the Ring II separation condition. As a result, a minimum in the desorbent usage of a tandem SMB occurred at the Y key RingI level where the two aforementioned factors could be balanced with each other. If such an optimal Y key RingI level was adopted, the desorbent usage could be reduced by up to 25%. It was also found that as the throughput of a tandem SMB became higher, the factor related to the migration of the Ring I key-product into Ring II was more influential in the performances of a tandem SMB than the factor related to the dilution of the stream from Ring I to Ring II. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of a wettability-gradient surface on copper by screen-printing techniques

NASA Astrophysics Data System (ADS)

Huang, Ding-Jun; Leu, Tzong-Shyng

2015-08-01

In this study, a screen-printing technique is utilized to fabricate a wettability-gradient surface on a copper substrate. The pattern definitions on the copper surface were freely fabricated to define the regions with different wettabilities, for which the printing definition technique was developed as an alternative to the existing costly photolithography techniques. This fabrication process using screen printing in tandem with chemical modification methods can easily realize an excellent wettability-gradient surface with superhydrophobicity and superhydrophilicity. Surface analyses were performed to characterize conditions in some fabrication steps. A water droplet movement sequence is provided to clearly demonstrate the droplet-driving effectiveness of the fabricated gradient surface. The droplet-driving efficiency offers a promising solution for condensation heat transfer applications in the foreseeable future.

Microfabricated polymer injector for direct mass spectrometry coupling.

PubMed

Gobry, Véronique; van Oostrum, Jan; Martinelli, Marco; Rohner, Tatiana C; Reymond, Frédéric; Rossier, Joël S; Girault, Hubert H

2002-04-01

This paper demonstrates the coupling of a plasma etched polymer microfluidic system with an electrospray mass spectrometer by generation of a nanospray. Taking advantage of the microtechnology processes and polymer properties, high volume production with good reproducibility of hydrophobic interfaces could be obtained. The nanospray was directly produced from the outlet of the plastic microfabricated chip positioned in front of the capillary entrance of the mass spectrometer. No chemical background due to the polymer has been observed under standard nanospray conditions. The performances of the spray as well as its efficiency have been demonstrated by flow measurements, stability establishment and tandem mass spectrometry experiment on angiotensin II. The spray was actuated without additional flow in methanol: water:acetic acid (50:49:1%) solution. A 40 fmol/microL detection limit could be reached.

Degradation of trimethoprim by gamma irradiation in the presence of persulfate

NASA Astrophysics Data System (ADS)

Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

2016-10-01

The degradation and mineralization of trimethoprim (TMP) by gamma irradiation was investigated in the presence of persulfate (PS). The TMP was degraded at initial concentration of 20 mg/L in aqueous solution with addition of 0, 0.5, 1, 1.5, 2 mM persulfate respectively. The effect of pH values (6.5, 7.5 and 8.5) on TMP degradation was also determined. The experimental results showed that the degradation and mineralization of TMP could be significantly enhanced by persulfate at acidic condition (pH=6.5). Several intermediate products generated during gamma irradiation process through hydroxylation, demethylation and cleavage were identified using liquid chromatography with tandem mass spectrometry (HPLC-MS). The degradation pathway of TMP was tentatively proposed based on the identification of intermediate products.

Terrestrial Reference Frame from GPS and SLR

NASA Astrophysics Data System (ADS)

Weiss, Jan; Bertiger, Willy; Desai, Shailen; Haines, Bruce; Sibois, Aurore

2015-04-01

We present strategies for realizing the terrestrial reference frame (TRF) using tracking data from terrestrial GPS receivers alone and in tandem with the GRACE and LAGEOS satellites. We generate solutions without apriori ties to the International Terrestrial Reference Frame (ITRF). Our approach relies on processing multi-day orbit arcs to take advantage of the satellite dynamics, GPS receiver and transmitter calibrations derived from low-Earth orbiter (LEO) data, and estimation strategies tuned for realizing a stable and accurate TRF. We furthermore take advantage of the geometric diversity provided by GPS tracking from GRACE, and explore the impacts of including ground-based satellite laser range (SLR) measurements to LAGEOS-1 and -2 with local ties relating the two geodetic techniques. We process data from 2003-2014 and compute Helmert transformations relative to ITRF/IGb08. With GPS alone we achieve a 3D origin offset and rate of <7 mm and <1 mm/yr, and reduce the offset to <4 mm when GRACE is included in the global solutions. Scale bias and rate are 3.1 ppb and 0.01 ppb/yr in either solution. Including SLR tracking from 11 ground stations to the LAGEOS satellites from 2012-2014 yields a reduction in scale bias of 0.5-1.0 ppb depending on the weight assigned to the SLR measurements. However, scatter is increased due to the relatively sparse SLR tracking network. We conclude with approaches for improving the TRF realized from GPS and SLR combined at the measurement level.

C70/C70:pentacene/pentacene organic heterojunction as the connecting layer for high performance tandem organic light-emitting diodes: Mechanism investigation of electron injection and transport

NASA Astrophysics Data System (ADS)

Guo, Qingxun; Yang, Dezhi; Chen, Jiangshan; Qiao, Xianfeng; Ahamad, Tansir; Alshehri, Saad M.; Ma, Dongge

2017-03-01

A high performance tandem organic light-emitting diode (OLED) is realized by employing a C70/C70:pentacene/pentacene organic heterojunction as the efficient charge generation layer (CGL). Not only more than two time enhancement of external quantum efficiency but also significant improvement in both power efficiency and lifetime are well achieved. The mechanism investigations find that the electron injection from the CGL to the adjacent electron transport layer (ETL) in tandem devices is injection rate-limited due to the high interface energy barrier between the CGL and the ETL. By the capacitance-frequency (C-F) and low temperature current density-voltage (J-V) characteristic analysis, we confirm that the electron transport is a space-charge-limited current process with exponential trap distribution. These traps are localized states below the lowest unoccupied molecular orbital edge inside the gap and would be filled with the upward shift of the Fermi level during the n-doping process. Furthermore, both the trap density (Ht) and the activation energy (Ea) could be carefully worked out through low temperature J-V measurements, which is very important for developing high performance tandem OLEDs.

Tungsten-188/carrier-free rhenium-188 perrhenic acid generator system

DOEpatents

Knapp, F.F. Jr.; Lisic, E.C.; Mirzadeh, S.; Callahan, A.P.

1994-01-04

A generator system has been invented for providing a carrier-free radioisotope in the form of an acid comprises a chromatography column in tandem fluid connection with an ion exchange column, the chromatography column containing a charge of a radioactive parent isotope. The chromatography column, charged with a parent isotope, is eluted with an alkali metal salt solution to generate the radioisotope in the form of an intermediate solution, which is passed through the ion-exchange column to convert the radioisotope to a carrier-free acid form. 1 figure.

Heterojunction PbS nanocrystal solar cells with oxide charge-transport layers.

PubMed

Hyun, Byung-Ryool; Choi, Joshua J; Seyler, Kyle L; Hanrath, Tobias; Wise, Frank W

2013-12-23

Oxides are commonly employed as electron-transport layers in optoelectronic devices based on semiconductor nanocrystals, but are relatively rare as hole-transport layers. We report studies of NiO hole-transport layers in PbS nanocrystal photovoltaic structures. Transient fluorescence experiments are used to verify the relevant energy levels for hole transfer. On the basis of these results, planar heterojunction devices with ZnO as the photoanode and NiO as the photocathode were fabricated and characterized. Solution-processed devices were used to systematically study the dependence on nanocrystal size and achieve conversion efficiency as high as 2.5%. Optical modeling indicates that optimum performance should be obtained with thinner oxide layers than can be produced reliably by solution casting. Room-temperature sputtering allows deposition of oxide layers as thin as 10 nm, which enables optimization of device performance with respect to the thickness of the charge-transport layers. The best devices achieve an open-circuit voltage of 0.72 V and efficiency of 5.3% while eliminating most organic material from the structure and being compatible with tandem structures.

Low-temperature-processed efficient semi-transparent planar perovskite solar cells for bifacial and tandem applications

PubMed Central

Fu, Fan; Feurer, Thomas; Jäger, Timo; Avancini, Enrico; Bissig, Benjamin; Yoon, Songhak; Buecheler, Stephan; Tiwari, Ayodhya N.

2015-01-01

Semi-transparent perovskite solar cells are highly attractive for a wide range of applications, such as bifacial and tandem solar cells; however, the power conversion efficiency of semi-transparent devices still lags behind due to missing suitable transparent rear electrode or deposition process. Here we report a low-temperature process for efficient semi-transparent planar perovskite solar cells. A hybrid thermal evaporation–spin coating technique is developed to allow the introduction of PCBM in regular device configuration, which facilitates the growth of high-quality absorber, resulting in hysteresis-free devices. We employ high-mobility hydrogenated indium oxide as transparent rear electrode by room-temperature radio-frequency magnetron sputtering, yielding a semi-transparent solar cell with steady-state efficiency of 14.2% along with 72% average transmittance in the near-infrared region. With such semi-transparent devices, we show a substantial power enhancement when operating as bifacial solar cell, and in combination with low-bandgap copper indium gallium diselenide we further demonstrate 20.5% efficiency in four-terminal tandem configuration. PMID:26576667

Low-temperature-processed efficient semi-transparent planar perovskite solar cells for bifacial and tandem applications.

PubMed

Fu, Fan; Feurer, Thomas; Jäger, Timo; Avancini, Enrico; Bissig, Benjamin; Yoon, Songhak; Buecheler, Stephan; Tiwari, Ayodhya N

2015-11-18

Semi-transparent perovskite solar cells are highly attractive for a wide range of applications, such as bifacial and tandem solar cells; however, the power conversion efficiency of semi-transparent devices still lags behind due to missing suitable transparent rear electrode or deposition process. Here we report a low-temperature process for efficient semi-transparent planar perovskite solar cells. A hybrid thermal evaporation-spin coating technique is developed to allow the introduction of PCBM in regular device configuration, which facilitates the growth of high-quality absorber, resulting in hysteresis-free devices. We employ high-mobility hydrogenated indium oxide as transparent rear electrode by room-temperature radio-frequency magnetron sputtering, yielding a semi-transparent solar cell with steady-state efficiency of 14.2% along with 72% average transmittance in the near-infrared region. With such semi-transparent devices, we show a substantial power enhancement when operating as bifacial solar cell, and in combination with low-bandgap copper indium gallium diselenide we further demonstrate 20.5% efficiency in four-terminal tandem configuration.

Development of Certified Reference Materials for Diarrhetic Shellfish Poisoning Toxins, Part 1: Calibration Solutions.

PubMed

Beach, Daniel G; Crain, Sheila; Lewis, Nancy; LeBlanc, Patricia; Hardstaff, William R; Perez, Ruth A; Giddings, Sabrina D; Martinez-Farina, Camilo F; Stefanova, Roumiana; Burton, Ian W; Kilcoyne, Jane; Melanson, Jeremy E; Quilliam, Michael A; McCarron, Pearse

2016-09-01

Okadaic acid (OA) and its analogs dinophysistoxins-1 (DTX1) and -2 (DTX2) are lipophilic polyethers produced by marine dinoflagellates. These toxins accumulate in shellfish and cause diarrhetic shellfish poisoning (DSP) in humans. Regulatory testing of shellfish is essential to safeguard public health and for international trade. Certified reference materials (CRMs) play a key role in analytical monitoring programs. This paper presents an overview of the interdisciplinary work that went into the planning, production, and certification of calibration-solution CRMs for OA, DTX1, and DTX2. OA and DTX1 were isolated from large-scale algal cultures and DTX2 from naturally contaminated mussels. Toxins were isolated by a combination of extraction and chromatographic steps with processes adapted to suit the source and concentration of each toxin. New 19-epi-DSP toxin analogs were identified as minor impurities. Once OA, DTX1, and DTX2 were established to be of suitable purity, solutions were prepared and dispensed into flame-sealed glass ampoules. Certification measurements were carried out using quantitative NMR spectroscopy and LC-tandem MS. Traceability of measurements was established through certified external standards of established purity. Uncertainties were assigned following standards and guidelines from the International Organization for Standardization, with components from the measurement, stability, and homogeneity studies being propagated into final combined uncertainties.

An Accelerated Analytical Process for the Development of STR Profiles for Casework Samples.

PubMed

Laurin, Nancy; Frégeau, Chantal J

2015-07-01

Significant efforts are being devoted to the development of methods enabling rapid generation of short tandem repeat (STR) profiles in order to reduce turnaround times for the delivery of human identification results from biological evidence. Some of the proposed solutions are still costly and low throughput. This study describes the optimization of an analytical process enabling the generation of complete STR profiles (single-source or mixed profiles) for human identification in approximately 5 h. This accelerated process uses currently available reagents and standard laboratory equipment. It includes a 30-min lysis step, a 27-min DNA extraction using the Promega Maxwell(®) 16 System, DNA quantification in <1 h using the Qiagen Investigator(®) Quantiplex HYres kit, fast amplification (<26 min) of the loci included in AmpFℓSTR(®) Identifiler(®), and analysis of the profiles on the 3500-series Genetic Analyzer. This combination of fast individual steps produces high-quality profiling results and offers a cost-effective alternative approach to rapid DNA analysis. © 2015 American Academy of Forensic Sciences.

Cooperative cell motility during tandem locomotion of amoeboid cells

PubMed Central

Bastounis, Effie; Álvarez-González, Begoña; del Álamo, Juan C.; Lasheras, Juan C.; Firtel, Richard A.

2016-01-01

Streams of migratory cells are initiated by the formation of tandem pairs of cells connected head to tail to which other cells subsequently adhere. The mechanisms regulating the transition from single to streaming cell migration remain elusive, although several molecules have been suggested to be involved. In this work, we investigate the mechanics of the locomotion of Dictyostelium tandem pairs by analyzing the spatiotemporal evolution of their traction adhesions (TAs). We find that in migrating wild-type tandem pairs, each cell exerts traction forces on stationary sites (∼80% of the time), and the trailing cell reuses the location of the TAs of the leading cell. Both leading and trailing cells form contractile dipoles and synchronize the formation of new frontal TAs with ∼54-s time delay. Cells not expressing the lectin discoidin I or moving on discoidin I–coated substrata form fewer tandems, but the trailing cell still reuses the locations of the TAs of the leading cell, suggesting that discoidin I is not responsible for a possible chemically driven synchronization process. The migration dynamics of the tandems indicate that their TAs’ reuse results from the mechanical synchronization of the leading and trailing cells’ protrusions and retractions (motility cycles) aided by the cell–cell adhesions. PMID:26912787

Low-Cost CdTe/Silicon Tandem Solar Cells

DOE PAGES

Tamboli, Adele C.; Bobela, David C.; Kanevce, Ana; ...

2017-09-06

Achieving higher photovoltaic efficiency in single-junction devices is becoming increasingly difficult, but tandem modules offer the possibility of significant efficiency improvements. By device modeling we show that four-terminal CdTe/Si tandem solar modules offer the prospect of 25%-30% module efficiency, and technoeconomic analysis predicts that these efficiency gains can be realized at costs per Watt that are competitive with CdTe and Si single junction alternatives. The cost per Watt of the modeled tandems is lower than crystalline silicon, but slightly higher than CdTe alone. But, these higher power modules reduce area-related balance of system costs, providing increased value especially in area-constrainedmore » applications. This avenue for high-efficiency photovoltaics enables improved performance on a near-term timeframe, as well as a path to further reduced levelized cost of electricity as module and cell processes continue to advance.« less

Low-Cost CdTe/Silicon Tandem Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamboli, Adele C.; Bobela, David C.; Kanevce, Ana

Achieving higher photovoltaic efficiency in single-junction devices is becoming increasingly difficult, but tandem modules offer the possibility of significant efficiency improvements. By device modeling we show that four-terminal CdTe/Si tandem solar modules offer the prospect of 25%-30% module efficiency, and technoeconomic analysis predicts that these efficiency gains can be realized at costs per Watt that are competitive with CdTe and Si single junction alternatives. The cost per Watt of the modeled tandems is lower than crystalline silicon, but slightly higher than CdTe alone. But, these higher power modules reduce area-related balance of system costs, providing increased value especially in area-constrainedmore » applications. This avenue for high-efficiency photovoltaics enables improved performance on a near-term timeframe, as well as a path to further reduced levelized cost of electricity as module and cell processes continue to advance.« less

Monitoring of Sea Ice Dynamic by Means of ERS-Envisat Tandem Cross-Interferometry

NASA Astrophysics Data System (ADS)

Pasquali, Paolo; Cantone, Alessio; Barbieri, Massimo; Engdahl, Marcus

2010-03-01

The interest in the monitoring of sea ice masses has increased greatly over the past decades for a variety of reasons. These include:- Navigation in northern latitude waters;- transportation of petroleum;- exploitation of mineral deposits in the Arctic, and- the use of icebergs as a source of fresh water.The availability of ERS-Envisat 28minute tandem acquisitions from dedicated campaigns, covering large areas in the northern latitudes with large geometrical baseline and very short temporal separation, allows the precise estimation of sea ice displacement fields with an accuracy that cannot be obtained on large scale from any other instrument. This article presents different results of sea ice dynamic monitoring over northern Canada obtained within the "ERS-Envisat Tandem Cross-Interferometry Campaigns: CInSAR processing and studies over extended areas" project from data acquired during the 2008-2009 Tandem campaign..

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells.

PubMed

Song, Zhaoning; Werner, Jérémie; Shrestha, Niraj; Sahli, Florent; De Wolf, Stefaan; Niesen, Björn; Watthage, Suneth C; Phillips, Adam B; Ballif, Christophe; Ellingson, Randy J; Heben, Michael J

2016-12-15

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.

Towards Development of Clustering Applications for Large-Scale Comparative Genotyping and Kinship Analysis Using Y-Short Tandem Repeats.

PubMed

Seman, Ali; Sapawi, Azizian Mohd; Salleh, Mohd Zaki

2015-06-01

Y-chromosome short tandem repeats (Y-STRs) are genetic markers with practical applications in human identification. However, where mass identification is required (e.g., in the aftermath of disasters with significant fatalities), the efficiency of the process could be improved with new statistical approaches. Clustering applications are relatively new tools for large-scale comparative genotyping, and the k-Approximate Modal Haplotype (k-AMH), an efficient algorithm for clustering large-scale Y-STR data, represents a promising method for developing these tools. In this study we improved the k-AMH and produced three new algorithms: the Nk-AMH I (including a new initial cluster center selection), the Nk-AMH II (including a new dominant weighting value), and the Nk-AMH III (combining I and II). The Nk-AMH III was the superior algorithm, with mean clustering accuracy that increased in four out of six datasets and remained at 100% in the other two. Additionally, the Nk-AMH III achieved a 2% higher overall mean clustering accuracy score than the k-AMH, as well as optimal accuracy for all datasets (0.84-1.00). With inclusion of the two new methods, the Nk-AMH III produced an optimal solution for clustering Y-STR data; thus, the algorithm has potential for further development towards fully automatic clustering of any large-scale genotypic data.

Rapid detection of peptide markers for authentication purposes in raw and cooked meat using ambient liquid extraction surface analysis mass spectrometry.

PubMed

Montowska, Magdalena; Alexander, Morgan R; Tucker, Gregory A; Barrett, David A

2014-10-21

In this Article, our previously developed ambient LESA-MS methodology is implemented to analyze five types of thermally treated meat species, namely, beef, pork, horse, chicken, and turkey meat, to select and identify heat-stable and species-specific peptide markers. In-solution tryptic digests of cooked meats were deposited onto a polymer surface, followed by LESA-MS analysis and evaluation using multivariate data analysis and tandem electrospray MS. The five types of cooked meat were clearly discriminated using principal component analysis and orthogonal partial least-squares discriminant analysis. 23 heat stable peptide markers unique to species and muscle protein were identified following data-dependent tandem LESA-MS analysis. Surface extraction and direct ambient MS analysis of mixtures of cooked meat species was performed for the first time and enabled detection of 10% (w/w) of pork, horse, and turkey meat and 5% (w/w) of chicken meat in beef, using the developed LESA-MS/MS analysis. The study shows, for the first time, that ambient LESA-MS methodology displays specificity sufficient to be implemented effectively for the analysis of processed and complex peptide digests. The proposed approach is much faster and simpler than other measurement tools for meat speciation; it has potential for application in other areas of meat science or food production.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, R.; Wilton, R.; Cuff, M. E.

The tandem Per-Arnt-Sim (PAS) like sensors are commonly found in signal transduction proteins. The periplasmic solute binding protein (SBP) domains are found ubiquitously and are generally involved in solute transport. These domains are widely observed as parts of separate proteins but not within the same polypeptide chain. We report the structural and biochemical characterization of the extracellular ligand-binding receptor, Dret_0059 from Desulfohalobium retbaense DSM 5692, an organism isolated from the Retba salt lake in Senegal. The structure of Dret_0059 consists of a novel combination of SBP and TPAS sensor domains. The N-terminal region forms an SBP domain and the C-terminalmore » region folds into a tandem PAS-like domain structure. A ketoleucine moiety is bound to the SBP, whereas a cytosine molecule is bound in the distal PAS domain of the TPAS. The differential scanning flourimetry studies in solution support the ligands observed in the crystal structure. There are only two other proteins with this structural architecture in the non-redundant sequence data base and we predict that they too bind the same substrates. There is significant interaction between the SBP and TPAS domains, and it is quite conceivable that the binding of one ligand will have an effect on the binding of the other. Our attempts to remove the ligands bound to the protein during expression were not successful, therefore, it is not clear what the relative affects are. The genomic context of this receptor does not contain any protein components expected for transport function, hence, we suggest that Dret_0059 is likely involved in signal transduction and not in solute transport.« less

Regio- and Stereoselective Cascades via Aldol Condensation and 1,3-Dipolar Cycloaddition for Construction of Functional Pyrrolizidine Derivatives.

PubMed

Mao, Zhuo-Ya; Liu, Yi-Wen; Han, Pan; Dong, Han-Qing; Si, Chang-Mei; Wei, Bang-Guo; Lin, Guo-Qiang

2018-02-16

An efficient and step-economical approach to access functionalized pyrrolizidine derivatives by a one-pot tandem sequence, including an aldol condensation and subsequent 1,3-dipolar cycloaddition process, has been developed, starting from acetone, aldehyde, and proline. A number of substituted aromatic aldehydes were amenable to this transformation, and the desired products, racemic 7a-7w and chiral 9a-9m, were obtained with excellent regioselectivities and outstanding diastereoselectivities. Moreover, in situ NMR studies revealed MgSO 4 could effectively promote the aldol condensation pathway in this tandem process.

Manufacturing of High-Efficiency Bi-Facial Tandem Concentrator Solar Cells: February 20, 2009--August 20, 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wojtczuk , S.

2011-06-01

Spire Semiconductor made concentrator photovoltaic (CPV) cells using a new bi-facial growth process and met both main program goals: a) 42.5% efficiency 500X (AM1.5D, 25C, 100mW/cm2); and b) Ready to supply at least 3MW/year of such cells at end of program. We explored a unique simple fabrication process to make a N/P 3-junction InGaP/GaAs/InGaAs tandem cells . First, the InGaAs bottom cell is grown on the back of a GaAs wafer. The wafers are then loaded into a cassette, spin-rinsed to remove particles, dipped in dilute NH4OH and spin-dried. The wafers are then removed from the cassette loaded the reactormore » for GaAs middle and InGaP top cell growth on the opposite wafer face (bi-facial growth). By making the epitaxial growth process a bit more complex, we are able to avoid more complex processing (such as large area wafer bonding or epitaxial liftoff) used in the inverted metamorphic (IMM) approach to make similar tandem stacks. We believe the yield is improved compared to an IMM process. After bi-facial epigrowth, standard III-V cell steps (back metal, photolithography for front grid, cap etch, AR coat, dice) are used in the remainder of the process.« less

Solution structure and function of the "tandem inactivation domain" of the neuronal A-type potassium channel Kv1.4.

PubMed

Wissmann, Ralph; Bildl, Wolfgang; Oliver, Dominik; Beyermann, Michael; Kalbitzer, Hans-Robert; Bentrop, Detlef; Fakler, Bernd

2003-05-02

Cumulative inactivation of voltage-gated (Kv) K(+) channels shapes the presynaptic action potential and determines timing and strength of synaptic transmission. Kv1.4 channels exhibit rapid "ball-and-chain"-type inactivation gating. Different from all other Kvalpha subunits, Kv1.4 harbors two inactivation domains at its N terminus. Here we report the solution structure and function of this "tandem inactivation domain" using NMR spectroscopy and patch clamp recordings. Inactivation domain 1 (ID1, residues 1-38) consists of a flexible N terminus anchored at a 5-turn helix, whereas ID2 (residues 40-50) is a 2.5-turn helix made up of small hydrophobic amino acids. Functional analysis suggests that only ID1 may work as a pore-occluding ball domain, whereas ID2 most likely acts as a "docking domain" that attaches ID1 to the cytoplasmic face of the channel. Deletion of ID2 slows inactivation considerably and largely impairs cumulative inactivation. Together, the concerted action of ID1 and ID2 may promote rapid inactivation of Kv1.4 that is crucial for the channel function in short term plasticity.

[Qualitative and quantitative analysis of amygdalin and its metabolite prunasin in plasma by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry].

PubMed

Gao, Meng; Wang, Yuesheng; Wei, Huizhen; Ouyang, Hui; He, Mingzhen; Zeng, Lianqing; Shen, Fengyun; Guo, Qiang; Rao, Yi

2014-06-01

A method was developed for the determination of amygdalin and its metabolite prunasin in rat plasma after intragastric administration of Maxing shigan decoction. The analytes were identified by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and quantitatively determined by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry. After purified by liquid-liquid extraction, the qualitative analysis of amygdalin and prunasin in the plasma sample was performed on a Shim-pack XR-ODS III HPLC column (75 mm x 2.0 mm, 1.6 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on a Triple TOF 5600 quadrupole time of flight mass spectrometer. The quantitative analysis of amygdalin and prunasin in the plasma sample was performed by separation on an Agilent C18 HPLC column (50 mm x 2.1 mm, 1.7 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on an AB Q-TRAP 4500 triple quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operated in negative ion mode and multiple-reaction monitoring (MRM) mode. The qualitative analysis results showed that amygdalin and its metabolite prunasin were detected in the plasma sample. The quantitative analysis results showed that the linear range of amygdalin was 1.05-4 200 ng/mL with the correlation coefficient of 0.999 0 and the linear range of prunasin was 1.25-2 490 ng/mL with the correlation coefficient of 0.997 0. The method had a good precision with the relative standard deviations (RSDs) lower than 9.20% and the overall recoveries varied from 82.33% to 95.25%. The limits of detection (LODs) of amygdalin and prunasin were 0.50 ng/mL. With good reproducibility, the method is simple, fast and effective for the qualitative and quantitative analysis of the amygdalin and prunasin in plasma sample of rats which were administered by Maxing shigan decoction.

Cyclodextrin-enhanced extraction and energy transfer of carcinogens in complex oil environments.

PubMed

Serio, Nicole; Chanthalyma, Chitapom; Prignano, Lindsey; Levine, Mindy

2013-11-27

Reported herein is the use of γ-cyclodextrin for two tandem functions: (a) the extraction of carcinogenic polycyclic aromatic hydrocarbons (PAHs) from oil samples into aqueous solution and (b) the promotion of highly efficient energy transfer from the newly extracted PAHs to a high-quantum-yield fluorophore. The extraction proceeded in moderate to good efficiencies, and the resulting cyclodextrin-promoted energy transfer led to a new, brightly fluorescent signal in aqueous solution. The resulting dual-function system (extraction followed by energy transfer) has significant relevance in the environmental detection and cleanup of oil-spill-related carcinogens.

Hybrid lead halide perovskites for light energy conversion: Excited state properties and photovoltaic applications

NASA Astrophysics Data System (ADS)

Manser, Joseph S.

The burgeoning class of metal halide perovskites constitutes a paradigm shift in the study and application of solution-processed semiconductors. Advancements in thin film processing and our understanding of the underlying structural, photophysical, and electronic properties of these materials over the past five years have led to development of perovskite solar cells with power conversion efficiencies that rival much more mature first and second-generation commercial technologies. It seems only a matter of time before the real-world impact of these compounds is put to the test. Like oxide perovskites, metal halide perovskites have ABX3 stoichiometry, where typically A is a monovalent cation, B a bivalent post-transition metal, and X a halide anion. Characterizing the behavior of photogenerated charges in metal halide perovskites is integral for understanding the operating principles and fundamental limitations of perovskite optoelectronics. The majority of studies outlined in this dissertation involve fundamental study of the prototypical organic-inorganic compound methylammonium lead iodide (CH3NH3PbI 3). Time-resolved pump-probe spectroscopy serves as a principle tool in these investigations. Excitation of a semiconductor can lead to formation of a number different excited state species and electronic complexes. Through analysis of excited state decay kinetics and optical nonlinearities in perovskite thin films, we identify spontaneous formation of a large fraction of free electrons and holes, whose presence is requisite for efficient photovoltaic operation. Following photogeneration of charge carriers in a semiconductor absorber, these species must travel large distances across the thickness of the material to realize large external quantum efficiencies and efficient carrier extraction. Using a powerful technique known as transient absorption microscopy, we directly image long-range carrier diffusion in a CH3NH3PbI 3 thin film. Charges are unambiguously shown to travel 220 nm over the course of 2 ns after photoexcitation, with an extrapolated diffusion length greater than one micrometer over the full excited state lifetime. The solution-processability of metal halide perovskites necessarily raises questions as to the properties of the solvated precursors and their connection to the final solid-state perovskite phase. Through structural and steady-state and time-resolved absorption studies, the important link between the excited state properties of the precursor components, composed of solvated and solid-state halometallate complexes, and CH3NH3PbI3 is evinced. This connection provides insight into optical nonlinearities and electronic properties of the perovskite phase. Fundamental studies of CH 3NH3PbI3 ultimately serve as a foundation for application of this and other related materials in high-performance devices. In the final chapter, the operation of CH3NH3PbI 3 solar cells in a tandem architecture is presented. The quest for economic, large scale hydrogen production has motivated the search for new materials and device designs capable of splitting water using only energy from the sun. In light of this, we introduce an all solution-processed tandem water splitting assembly composed of a BiVO4 photoanode and a single-junction CH3NH3PbI3 hybrid perovskite solar cell. This unique configuration allows efficient solar photon management, with the metal oxide photoanode selectively harvesting high energy visible photons and the underlying perovskite solar cell capturing lower energy visible-near IR wavelengths in a single-pass excitation. Operating without external bias under standard terrestrial one sun illumination, the photoanode-photovoltaic architecture, in conjunction with an earthabundant cobalt phosphate catalyst, exhibits a solar-to-hydrogen conversion efficiency of 2.5% at neutral pH. The design of low-cost tandem water splitting assemblies employing single-junction hybrid perovskite materials establishes a potentially promising new frontier for solar water splitting research.

Imaging Determinants of Clinical Effectiveness of Lumbar Transforaminal Epidural Steroid Injections.

PubMed

Maus, Timothy P; El-Yahchouchi, Christine A; Geske, Jennifer R; Carter, Rickey E; Kaufmann, Timothy J; Wald, John T; Diehn, Felix E

2016-12-01

To examine associations between imaging characteristics of compressive lesions and patient outcomes after lumbar transforaminal epidural steroid injections (TFESIs) stratified by steroid formulation (solution versus suspension). Retrospective observational study, academic radiology practice. A 516-patient sample was selected from 2,634 consecutive patients receiving lumbar TFESI for radicular pain. The advanced imaging study(s) preceding sampled TFESI were reviewed. Compressive lesions were described by a) nature of the lesion [disc herniation, fixed stenosis, synovial cyst, epidural fibrosis, no lesion] b) degree of neural compression [4 part scale], and c) presence of a tandem lesion. Associations between 2-month categorical outcomes (responder rates for pain, functional recovery) and imaging characteristics, stratified by steroid formulation, were examined with chi-squared tests of categorical outcomes and multivariable logistic regression models. Disc herniation patients had more responders for functional recovery than patients with fixed lesions (54% versus 38%, P = 0.01). Patients with fixed lesions receiving steroid solution (dexamethasone) had more responders for pain relief, with a similar trend for functional recovery, than patients receiving suspensions (59% versus 40%, P = 0.01). Outcomes for patients with fixed lesions treated with dexamethasone were not statistically different from those for disc herniation patients. Patients with single compressive lesions had more responders than those with tandem lesions (55% versus 41%, P = 0.03). In the entire sample, outcomes for disc herniations were more favorable than for fixed lesions. However, fixed lesions treated with dexamethasone had outcomes indistinguishable from disc herniations. Single lesions had better outcomes than tandem lesions. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Transport-related triplet states and hyperfine couplings in organic tandem solar cells probed by pulsed electrically detected magnetic resonance spectroscopy

NASA Astrophysics Data System (ADS)

Kraffert, Felix; Bahro, Daniel; Meier, Christoph; Denne, Maximilian; Colsmann, Alexander; Behrends, Jan

2017-09-01

Tandem solar cells constitute the most successful organic photovoltaic devices with power conversion efficiencies comparable to thin-film silicon solar cells. Especially their high open-circuit voltage - only achievable by a well-adjusted layer stacking - leads to their high efficiencies. Nevertheless, the microscopic processes causing the lossless recombination of charge carriers within the recombination zone are not well understood yet. We show that advanced pulsed electrically detected magnetic resonance techniques such as electrically detected (ED)-Rabi nutation measurements and electrically detected hyperfine sublevel correlation (ED-HYSCORE) spectroscopy help to understand the role of triplet excitons in these microscopic processes. We investigate fully working miniaturised organic tandem solar cells and detect current-influencing doublet states in different layers as well as triplet excitons located on the fullerene-based acceptor. We apply ED-HYSCORE in order to study the nuclear spin environment of the relevant electron/hole spins and detect a significant amount of the low abundant 13C nuclei coupled to the observer spins.

Suture retraction technique to prevent parent vessel obstruction following aneurysm tandem clipping.

PubMed

Rayan, Tarek; Amin-Hanjani, Sepideh

2015-08-01

With large or giant aneurysms, the use of multiple tandem clips can be essential for complete obliteration of the aneurysm. One potential disadvantage, however, is the considerable cumulative weight of these clips, which may lead to kinking of the underlying parent vessels and obstruction of flow. The authors describe a simple technique to address this problem, guided by intraoperative blood flow measurements, in a patient with a ruptured near-giant 2.2 × 1.7-cm middle cerebral artery bifurcation aneurysm that was treated with the tandem clipping technique. A total of 11 clips were applied in a vertical stacked fashion. The cumulative weight of the clips caused kinking of the temporal M2 branch of the bifurcation with reduction of flow. A 4-0 Nurolon suture tie was applied to the hub of one of the clips and was tethered to the dura of the sphenoid ridge by a small mini-clip and reinforced by application of tissue sealant. The patient underwent intraoperative indocyanine green videoangiography as well as catheter angiography, which demonstrated complete aneurysmal obliteration and preservation of vessel branches. Postoperative angiography confirmed patency of the bifurcation vessels with mild vasospasm. The patient had a full recovery with no postoperative complications and was neurologically intact at her 6-month follow-up. The suture retraction technique allows a simple solution to parent vessel obstruction following aneurysm tandem clipping, in conjunction with the essential guidance provided by intraoperative flow measurements.

Tandem mass spectrometry data quality assessment by self-convolution.

PubMed

Choo, Keng Wah; Tham, Wai Mun

2007-09-20

Many algorithms have been developed for deciphering the tandem mass spectrometry (MS) data sets. They can be essentially clustered into two classes. The first performs searches on theoretical mass spectrum database, while the second based itself on de novo sequencing from raw mass spectrometry data. It was noted that the quality of mass spectra affects significantly the protein identification processes in both instances. This prompted the authors to explore ways to measure the quality of MS data sets before subjecting them to the protein identification algorithms, thus allowing for more meaningful searches and increased confidence level of proteins identified. The proposed method measures the qualities of MS data sets based on the symmetric property of b- and y-ion peaks present in a MS spectrum. Self-convolution on MS data and its time-reversal copy was employed. Due to the symmetric nature of b-ions and y-ions peaks, the self-convolution result of a good spectrum would produce a highest mid point intensity peak. To reduce processing time, self-convolution was achieved using Fast Fourier Transform and its inverse transform, followed by the removal of the "DC" (Direct Current) component and the normalisation of the data set. The quality score was defined as the ratio of the intensity at the mid point to the remaining peaks of the convolution result. The method was validated using both theoretical mass spectra, with various permutations, and several real MS data sets. The results were encouraging, revealing a high percentage of positive prediction rates for spectra with good quality scores. We have demonstrated in this work a method for determining the quality of tandem MS data set. By pre-determining the quality of tandem MS data before subjecting them to protein identification algorithms, spurious protein predictions due to poor tandem MS data are avoided, giving scientists greater confidence in the predicted results. We conclude that the algorithm performs well and could potentially be used as a pre-processing for all mass spectrometry based protein identification tools.

Controlling the Morphology of BDTT-DPP-Based Small Molecules via End-Group Functionalization for Highly Efficient Single and Tandem Organic Photovoltaic Cells.

PubMed

Kim, Ji-Hoon; Park, Jong Baek; Yang, Hoichang; Jung, In Hwan; Yoon, Sung Cheol; Kim, Dongwook; Hwang, Do-Hoon

2015-11-04

A series of narrow-band gap, π-conjugated small molecules based on diketopyrrolopyrrole (DPP) electron acceptor units coupled with alkylthienyl-substituted-benzodithiophene (BDTT) electron donors were designed and synthesized for use as donor materials in solution-processed organic photovoltaic cells. In particular, by end-group functionalization of the small molecules with fluorine derivatives, the nanoscale morphologies of the photoactive layers of the photovoltaic cells were successfully controlled. The influences of different fluorine-based end-groups on the optoelectronic and morphological properties, carrier mobilities, and the photovoltaic performances of these materials were investigated. A high power conversion efficiency (PCE) of 6.00% under simulated solar light (AM 1.5G) illumination has been achieved for organic photovoltaic cells based on a small-molecule bulk heterojunction system consisting of a trifluoromethylbenzene (CF3) end-group-containing oligomer (BDTT-(DPP)2-CF3) as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. As a result, the introduction of CF3 end-groups has been found to enhance both the short circuit current density (JSC) and fill factor (FF). A tandem photovoltaic device comprising an inverted BDTT-(DPP)2-CF3:PC71BM cell and a poly(3-hexylthiophene) (P3HT):indene-C60-bisadduct (IC60BA)-based cell as the top and bottom cell components, respectively, showed a maximum PCE of 8.30%. These results provide valuable guidelines for the rational design of conjugated small molecules for applications in high-performance organic photovoltaic cells. Furthermore, to the best of our knowledge, this is the first report on the design of fluorine-functionalized BDTT-DPP-based small molecules, which have been shown to be a viable candidate for use in inverted tandem cells.

A new technique for high performance tandem time-of- flight mass spectrometry

NASA Astrophysics Data System (ADS)

Katz, Daniel Louis

2001-08-01

The main result of this written dissertation is a mathematical solution to the problem of multiplex recording for high performance tandem time-of-flight mass spectrometry. The prescription is to use a time-lag accelerator in the second stage to match the ion optical properties of the decay fragments to the requirements of the electrostatic ion mirror. With this technique the ion mirror is able to focus the full mass range of fragment ions at a single voltage setting, permitting acquisition of the entire mass spectrum from a single ionization event. This work was performed in support of a joint project carried out by researchers at Oregon State University and The University of Uppsala, Sweden, to design, build and test a tandem instrument featuring precision selection of the precursor species in the first stage of the spectrometer, a means of fragmenting the precursor species, and multiplex recording of the resulting fragment spectrum in the second stage. A patent application has been filed on the complete instrument with the United States Patent Office, a copy of which has been included as an appendix, and a prototype of that instrument has been constructed and awaits testing at Oregon State University.

Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

DOE PAGES

Werner, Jeremie; Barraud, Loris; Walter, Arnaud; ...

2016-07-30

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cell candidates, but their typical device size (<0.2 cm 2), is still far from standard industrial sizes. Here, we present a 1 cm 2 near-infrared transparent perovskite solar cell with 14.5% steadystate efficiency, as compared to 16.4% on 0.25 cm 2. By mechanically stacking these cells with silicon heterojunction cells, we experimentally demonstrate a 4-terminal tandem measurement with a steady-state efficiency ofmore » 25.2%, with a 0.25 cm 2 top cell. The developed top cell processing methods enable the fabrication of a 20.5% efficient and 1.43 cm 2 large monolithic perovskite/silicon heterojunction tandem solar cell, featuring a rear-side textured bottom cell to increase its near-infrared spectral response. Finally, we compare both tandem configurations to identify efficiency-limiting factors and discuss the potential for further performance improvement.« less

Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werner, Jeremie; Barraud, Loris; Walter, Arnaud

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cell candidates, but their typical device size (<0.2 cm 2), is still far from standard industrial sizes. Here, we present a 1 cm 2 near-infrared transparent perovskite solar cell with 14.5% steadystate efficiency, as compared to 16.4% on 0.25 cm 2. By mechanically stacking these cells with silicon heterojunction cells, we experimentally demonstrate a 4-terminal tandem measurement with a steady-state efficiency ofmore » 25.2%, with a 0.25 cm 2 top cell. The developed top cell processing methods enable the fabrication of a 20.5% efficient and 1.43 cm 2 large monolithic perovskite/silicon heterojunction tandem solar cell, featuring a rear-side textured bottom cell to increase its near-infrared spectral response. Finally, we compare both tandem configurations to identify efficiency-limiting factors and discuss the potential for further performance improvement.« less

Effective application of multiple locus variable number of tandem repeats analysis to tracing Staphylococcus aureus in food-processing environment.

PubMed

Rešková, Z; Koreňová, J; Kuchta, T

2014-04-01

A total of 256 isolates of Staphylococcus aureus were isolated from 98 samples (34 swabs and 64 food samples) obtained from small or medium meat- and cheese-processing plants in Slovakia. The strains were genotypically characterized by multiple locus variable number of tandem repeats analysis (MLVA), involving multiplex polymerase chain reaction (PCR) with subsequent separation of the amplified DNA fragments by an automated flow-through gel electrophoresis. With the panel of isolates, MLVA produced 31 profile types, which was a sufficient discrimination to facilitate the description of spatial and temporal aspects of contamination. Further data on MLVA discrimination were obtained by typing a subpanel of strains by multiple locus sequence typing (MLST). MLVA coupled to automated electrophoresis proved to be an effective, comparatively fast and inexpensive method for tracing S. aureus contamination of food-processing factories. Subspecies genotyping of microbial contaminants in food-processing factories may facilitate identification of spatial and temporal aspects of the contamination. This may help to properly manage the process hygiene. With S. aureus, multiple locus variable number of tandem repeats analysis (MLVA) proved to be an effective method for the purpose, being sufficiently discriminative, yet comparatively fast and inexpensive. The application of automated flow-through gel electrophoresis to separation of DNA fragments produced by multiplex PCR helped to improve the accuracy and speed of the method. © 2013 The Society for Applied Microbiology.

Continuous processing of recombinant proteins: integration of refolding and purification using simulated moving bed size-exclusion chromatography with buffer recycling.

PubMed

Wellhoefer, Martin; Sprinzl, Wolfgang; Hahn, Rainer; Jungbauer, Alois

2014-04-11

Continuous processing of recombinant proteins was accomplished by combining continuous matrix-assisted refolding and purification by tandem simulated moving bed (SMB) size-exclusion chromatography (SEC). Recombinant proteins, N(pro) fusion proteins from inclusion bodies were dissolved with NaOH and refolded in the SMB system with a closed-loop set-up with refolding buffer as the desorbent buffer and buffer recycling of the refolding buffer of the raffinate by tangential flow filtration. For further purification of the refolded proteins, a second SMB operation also based on SEC was added. The whole system could be operated isocratically with refolding buffer as the desorbent buffer, and buffer recycling could also be applied in the purification step. Thus, a significant reduction in buffer consumption was achieved. The system was evaluated with two proteins, the N(pro) fusion pep6His and N(pro) fusion MCP-1. Refolding solution, which contained residual N(pro) fusion peptide, the cleaved autoprotease N(pro), and the cleaved target peptide was used as feed solution. Full separation of the cleaved target peptide from residual proteins was achieved at a purity and recovery in the raffinate and extract, respectively, of approximately 100%. In addition, more than 99% of the refolding buffer of the raffinate was recycled. A comparison of throughput, productivity, and buffer consumption of the integrated continuous process with two batch processes demonstrated that up to 60-fold higher throughput, up to 180-fold higher productivity, and at least 28-fold lower buffer consumption can be obtained by the integrated continuous process, which compensates for the higher complexity. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous analysis of nine aromatic amines in mainstream cigarette smoke using online solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Jie; Bai, Ruoshi; Zhou, Zhaojuan; Liu, Xingyu; Zhou, Jun

2017-04-01

A fully automated analytical method was developed and validated by this present study. The method was based on two-dimensional (2D) online solid-phase extraction liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) to determine nine aromatic amines (AAs) in mainstream smoke (MSS) simultaneously. As a part of validation process, AAs yields for 16 top-selling commercial cigarettes from China market were evaluated by the developed method under both Health Canada Intensive (HCI) and ISO machine smoking regimes. The gas phase of MSS was trapped by 25 mL 0.6 M hydrochloric acid solution, while the particulate phase was collected on a glass fiber filter. Then, the glass fiber pad was extracted with hydrochloric acid solution in an ultrasonic bath. The extract was analyzed with 2D online SPE-LC-MS/MS. In order to minimize the matrix effects of sample on each analyte, two cartridges with different extraction mechanisms were utilized to cleanup disturbances of different polarity, which were performed by the 2D SPE. A phenyl-hexyl analytical column was used to achieve a chromatographic separation. Under the optimized conditions, the isomers of p-toluidine, m-toluidine and o-toluidine, 3-aminobiphenyl and 4-aminobiphenyl, and 1-naphthylamine and 2-naphthylamine were baseline separated with good peak shapes for the first time. The limits of detection for nine AAs ranged from 0.03 to 0.24 ng cig -1 . The recovery of the measurement of nine AAs was from 84.82 to 118.47%. The intra-day and inter-day precisions of nine AAs were less than 10 and 16%, respectively. Compared with ISO machine smoking regime, the AAs yields in MSS were 1.17 to 3.41 times higher under HCI machine smoking regime. Graphical abstract New method using online SPE-LC/MS/MS for analysis of aromatic amines in mainstream cigarette smoke.

Integrating and analyzing medical and environmental data using ETL and Business Intelligence tools.

PubMed

Villar, Alejandro; Zarrabeitia, María T; Fdez-Arroyabe, Pablo; Santurtún, Ana

2018-06-01

Processing data that originates from different sources (such as environmental and medical data) can prove to be a difficult task, due to the heterogeneity of variables, storage systems, and file formats that can be used. Moreover, once the amount of data reaches a certain threshold, conventional mining methods (based on spreadsheets or statistical software) become cumbersome or even impossible to apply. Data Extract, Transform, and Load (ETL) solutions provide a framework to normalize and integrate heterogeneous data into a local data store. Additionally, the application of Online Analytical Processing (OLAP), a set of Business Intelligence (BI) methodologies and practices for multidimensional data analysis, can be an invaluable tool for its examination and mining. In this article, we describe a solution based on an ETL + OLAP tandem used for the on-the-fly analysis of tens of millions of individual medical, meteorological, and air quality observations from 16 provinces in Spain provided by 20 different national and regional entities in a diverse array for file types and formats, with the intention of evaluating the effect of several environmental variables on human health in future studies. Our work shows how a sizable amount of data, spread across a wide range of file formats and structures, and originating from a number of different sources belonging to various business domains, can be integrated in a single system that researchers can use for global data analysis and mining.

Integrating and analyzing medical and environmental data using ETL and Business Intelligence tools

NASA Astrophysics Data System (ADS)

Villar, Alejandro; Zarrabeitia, María T.; Fdez-Arroyabe, Pablo; Santurtún, Ana

2018-03-01

Processing data that originates from different sources (such as environmental and medical data) can prove to be a difficult task, due to the heterogeneity of variables, storage systems, and file formats that can be used. Moreover, once the amount of data reaches a certain threshold, conventional mining methods (based on spreadsheets or statistical software) become cumbersome or even impossible to apply. Data Extract, Transform, and Load (ETL) solutions provide a framework to normalize and integrate heterogeneous data into a local data store. Additionally, the application of Online Analytical Processing (OLAP), a set of Business Intelligence (BI) methodologies and practices for multidimensional data analysis, can be an invaluable tool for its examination and mining. In this article, we describe a solution based on an ETL + OLAP tandem used for the on-the-fly analysis of tens of millions of individual medical, meteorological, and air quality observations from 16 provinces in Spain provided by 20 different national and regional entities in a diverse array for file types and formats, with the intention of evaluating the effect of several environmental variables on human health in future studies. Our work shows how a sizable amount of data, spread across a wide range of file formats and structures, and originating from a number of different sources belonging to various business domains, can be integrated in a single system that researchers can use for global data analysis and mining.

Integrating and analyzing medical and environmental data using ETL and Business Intelligence tools

NASA Astrophysics Data System (ADS)

Villar, Alejandro; Zarrabeitia, María T.; Fdez-Arroyabe, Pablo; Santurtún, Ana

2018-06-01

Processing data that originates from different sources (such as environmental and medical data) can prove to be a difficult task, due to the heterogeneity of variables, storage systems, and file formats that can be used. Moreover, once the amount of data reaches a certain threshold, conventional mining methods (based on spreadsheets or statistical software) become cumbersome or even impossible to apply. Data Extract, Transform, and Load (ETL) solutions provide a framework to normalize and integrate heterogeneous data into a local data store. Additionally, the application of Online Analytical Processing (OLAP), a set of Business Intelligence (BI) methodologies and practices for multidimensional data analysis, can be an invaluable tool for its examination and mining. In this article, we describe a solution based on an ETL + OLAP tandem used for the on-the-fly analysis of tens of millions of individual medical, meteorological, and air quality observations from 16 provinces in Spain provided by 20 different national and regional entities in a diverse array for file types and formats, with the intention of evaluating the effect of several environmental variables on human health in future studies. Our work shows how a sizable amount of data, spread across a wide range of file formats and structures, and originating from a number of different sources belonging to various business domains, can be integrated in a single system that researchers can use for global data analysis and mining.

High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites.

PubMed

Sutter-Fella, Carolin M; Li, Yanbo; Amani, Matin; Ager, Joel W; Toma, Francesca M; Yablonovitch, Eli; Sharp, Ian D; Javey, Ali

2016-01-13

Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH3NH3PbI3-xBrx perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamic range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ Eg ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter-Fella, Carolin M.; Li, Yanbo; Amani, Matin

Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH 3NH 3PbI 3-xBr x perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamicmore » range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ E g ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells. (Figure Presented).« less

Multi-walled carbon nanotubes as solid-phase extraction sorbents for simultaneous determination of type A trichothecenes in maize, wheat and rice by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Dong, Maofeng; Si, Wenshuai; Jiang, Keqiu; Nie, Dongxia; Wu, Yongjiang; Zhao, Zhihui; De Saeger, Sarah; Han, Zheng

2015-12-04

A solid-phase extraction (SPE) procedure using multi-walled carbon nanotubes (MWCNTs) as sorbents coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for simultaneous determination of four type A trichothecenes in maize, wheat and rice for the first time. Several key parameters including the composition of sample loading solutions, washing and elution solvents were thoroughly investigated to achieve optimal SPE recoveries and efficiency. Performance of the MWCNTs materials was significantly affected by pH, and after optimization, n-hexane and 5% methanol aqueous solution as the washing solutions and methanol containing 1% formic acid as the elution solvent presented an excellent purification efficiency for the four targets in the different matrices. The method was validated by determining the linearity (R(2)≥0.992), recovery (73.4-113.7%), precision (1.2-17.1%) and sensitivity (limit of quantification in the range of 0.02-0.10μg/kg), and was further applied for simultaneous determination of type A trichothecenes in 30 samples. Although low contamination levels of type A trichothecenes in wheat, maize and rice were observed revealing mitigated risks to consumers in Shanghai, China, the developed method has proven to be a valuable tool for type A trichothecenes monitoring in complex crop matrices. Copyright © 2015 Elsevier B.V. All rights reserved.

[Simultaneous determination of zeranols and chloramphenicol in foodstuffs of animal origin by combination immunoaffinity column clean-up and liquid chromatography-tandem mass spectrometry].

PubMed

Wang, Qing; Wang, Guomin; Xi, Cunxian; Li, Xianliang; Chen, Dongdong; Tang, Bobin; Zhang, Lei; Zhao, Hua

2014-06-01

A combination immunoaffinity column (IAC-CZ) clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method was successfully developed for zearalenol, beta-zearalenol and zearalenone) and chloramphenicol (CAP) in foodstuffs of animal origin. The samples (fish, liver, milk and honey) were enzymatically digested by beta-glucuronidase/sulfatase for about 16 h and then extracted with ether. The extracts were evaporated to dryness and then the residues were dissolved by 1.0 mL of 50% acetonitrile solution. After filtered and diluted with PBS buffer, the reconstituted solution were cleaned-up with a IAC-CZ and then analyzed by LC-MS/MS in multiple reaction monitoring (MRM) mode. The chromatographic separation was performed on a Shimadzu Shim-pack VP-ODS column with gradient elution by acetonitrile and 2 mmol/L ammonium acetate solution. The detection was carried out by electrospray negative ionization mass spectrometry in MRM mode. The proposed method was validated by the limit of detection (0.04-0.10 microg/kg), linearity (R2 > or = 0.999 0), average recoveries (70.9%-95.6%) and precisions (2.0% - 11.8%). The developed method is reliable, sensitive and has good applicability. The combination immunoaffinity column was proved to be an effective pretreatment technique to decrease the matrix effect, and it met the requirements of residue analysis of co-occurring zeranols and chloramphenicol.

Quantitative Assessment of In-solution Digestion Efficiency Identifies Optimal Protocols for Unbiased Protein Analysis*

PubMed Central

León, Ileana R.; Schwämmle, Veit; Jensen, Ole N.; Sprenger, Richard R.

2013-01-01

The majority of mass spectrometry-based protein quantification studies uses peptide-centric analytical methods and thus strongly relies on efficient and unbiased protein digestion protocols for sample preparation. We present a novel objective approach to assess protein digestion efficiency using a combination of qualitative and quantitative liquid chromatography-tandem MS methods and statistical data analysis. In contrast to previous studies we employed both standard qualitative as well as data-independent quantitative workflows to systematically assess trypsin digestion efficiency and bias using mitochondrial protein fractions. We evaluated nine trypsin-based digestion protocols, based on standard in-solution or on spin filter-aided digestion, including new optimized protocols. We investigated various reagents for protein solubilization and denaturation (dodecyl sulfate, deoxycholate, urea), several trypsin digestion conditions (buffer, RapiGest, deoxycholate, urea), and two methods for removal of detergents before analysis of peptides (acid precipitation or phase separation with ethyl acetate). Our data-independent quantitative liquid chromatography-tandem MS workflow quantified over 3700 distinct peptides with 96% completeness between all protocols and replicates, with an average 40% protein sequence coverage and an average of 11 peptides identified per protein. Systematic quantitative and statistical analysis of physicochemical parameters demonstrated that deoxycholate-assisted in-solution digestion combined with phase transfer allows for efficient, unbiased generation and recovery of peptides from all protein classes, including membrane proteins. This deoxycholate-assisted protocol was also optimal for spin filter-aided digestions as compared with existing methods. PMID:23792921

HATCN-based charge recombination layers as effective interconnectors for tandem organic solar cells.

PubMed

Wang, Rong-Bin; Wang, Qian-Kun; Xie, Hao-Jun; Xu, Lu-Hai; Duhm, Steffen; Li, Yan-Qing; Tang, Jian-Xin

2014-09-10

A comprehensive understanding of the energy-level alignment at the organic heterojunction interfaces is of paramount importance to optimize the performance of organic solar cells (OSCs). Here, the detailed electronic structures of organic interconnectors, consisting of cesium fluoride-doped 4,7-diphenyl-1,10-phenanthroline and hexaazatriphenylene-hexacarbonitrile (HATCN), have been investigated via in situ photoemission spectroscopy, and their impact on the charge recombination process in tandem OSCs has been identified. The experimental determination shows that the HATCN interlayer plays a significant role in the interface energetics with a dramatic decrease in the reverse built-in potential for electrons and holes from stacked subcells, which is beneficial to the charge recombination between HATCN and the adjacent layer. In accordance with the energy-level alignments, the open-circuit voltage of tandem OSC incorporating a HATCN-based interconnector is almost 2 times that of a single-cell OSC, revealing the effectiveness of the HATCN-based interconnectors in tandem organic devices.

A thermoresponsive nanorattle containing two different catalysts for controllable one-pot tandem catalysis

NASA Astrophysics Data System (ADS)

Niu, Chengrong; Hu, Jie; Li, Yinfeng; Leng, Jinghang; Li, Songjun

2018-03-01

In the present work, a thermoresponsive nanorattle with a Ag nanoparticle (NP) core (one catalyst in the nanorattle), and a poly(N-isopropylacrylamide) shell was developed. An imidazole group was grafted on the polymer shell by copolymerization as the other catalyst. Owing to the catalytic activities of the imidazole group and Ag NP with regards to hydrolysis and reduction, respectively, this nanorattle exhibited tandem-reaction catalytic abilities. In addition, because of the shrinkage of the poly(N-isopropylacrylamide) shell at high temperatures, the tandem reaction could be controlled to stop at the first reaction step. That is to say, only the hydrolysis reaction was catalyzed by the imidazole group being grafted on the surface of the shell. The reduction step in the tandem reaction catalyzed by the Ag particle, however, was switched off by the shrinkage of the poly(N-isopropylacrylamide) shell. This protocol opens up an opportunity to develop controllable catalysts for complicated chemical processes.

Synthesis of oxazolidine-2,4-diones by a tandem phosphorus-mediated carboxylative condensation-cyclization reaction using atmospheric carbon dioxide.

PubMed

Zhang, Wen-Zhen; Xia, Tian; Yang, Xu-Tong; Lu, Xiao-Bing

2015-04-11

The oxazolidine-2,4-dione motif is found frequently in biologically important compounds. A tandem phosphorus-mediated carboxylative condensation of primary amines and α-ketoesters/base-catalyzed cyclization reaction have been developed. These processes provide a novel and convenient access to various oxazolidine-2,4-diones in a one-pot fashion using atmospheric carbon dioxide and readily available substrates under very mild and transition-metal-free conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soliman, A; Elzibak, A; Fatemi, A

Purpose: To quantitatively evaluate the MR image quality of a novel direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer, using the clinical MRI scanning protocol for image guided brachytherapy. Methods: The tungsten alloy-based applicator was placed in a water phantom and clinical imaging protocol was performed. Axial images were acquired using 2D turbo-spin echo (TSE) T2-weighted sequence on a 1.5T GE 450w MR scanner and an 8-channel body coil. As multi-channel receiver coil was used, inhomogeneities in the B1 receive field must be considered before performing the quantification process. Therefore the applicator was removed from the phantom and themore » whole imaging session was performed again for the water phantom with the same parameters. Images from the two scans were then subtracted, resulting in a difference image that only shows the applicator with its surrounding magnetic susceptibility dipole artifact. Line profiles were drawn and plotted on the difference image at various angles and locations along the tandem. Full width at half maximum (FWHM) was measured at all the line profiles to quantify the extent of the artifact. Additionally, the extent of the artifact along the diameter of the tandem was measured at various angles and locations. Results: After removing the background inhomogeneities of the receiver coil, FWHM of the tandem measured 5.75 ± 0.35 mm (the physical tandem diameter is 5.4 mm). The average extent of the artifacts along the diameter of the tandem measured is 2.14 ± 0.56 mm. In contrast to CT imaging of the same applicator (not shown here), the tandem can be easily identified without additional correction algorithms. Conclusion: This work demonstrated that the novel DMBT tandem applicator has minimal susceptibility artifact in T2-weighted images employed in clinical practice for MRI-guided brachytherapy of cervical cancer.« less

Determination of ochratoxin A and T-2 toxin in alcoholic beverages by hollow fiber liquid phase microextraction and ultra high-pressure liquid chromatography coupled to tandem mass spectrometry.

PubMed

Romero-González, R; Frenich, A Garrido; Vidal, J L Martínez; Aguilera-Luiz, M M

2010-06-30

A new method for the determination of ochratoxin A and T-2 toxin in alcoholic beverages (wine and beer) by hollow fiber liquid microextraction was optimized. The extraction step was followed by ultra high-pressure liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The extraction procedure was based on the extraction of mycotoxins from the sample to the organic solvent (1-octanol) immobilized in the fiber, and afterwards, they were desorbed in a mixture of acetonitrile/water (80:20, v/v) at pH 7 prior to chromatographic determination. Different variables affecting the extraction process such as organic solvent, salt content, extraction time and desorption solution were studied. The developed method was validated in wine and beer, using white wine and alcoholic beer as representative matrices for both types of samples. Relative recoveries higher than 70% were obtained for the selected mycotoxins. Good linearity (R(2)>0.993) was obtained and quantification limits (0.02-0.09 microg L(-1)) below European regulatory levels were achieved. Repeatability, expressed as relative standard deviation, was always lower than 12%, whereas interday precision was lower than 21%. The proposed method was applied to the analysis of several types of wines and beers and ochratoxin A was detected in a rosé wine at 1.1 microg L(-1). Copyright 2010 Elsevier B.V. All rights reserved.

Mechanism for recognition of polyubiquitin chains: balancing affinity through interplay between multivalent binding and dynamics.

PubMed

Markin, Craig J; Xiao, Wei; Spyracopoulos, Leo

2010-08-18

RAP80 plays a key role in signal transduction in the DNA damage response by recruiting proteins to DNA damage foci by binding K63-polyubiquitin chains with two tandem ubiquitin-interacting motifs (tUIM). It is generally recognized that the typically weak interaction between ubiquitin (Ub) and various recognition motifs is intensified by themes such as tandem recognition motifs and Ub polymerization to achieve biological relevance. However, it remains an intricate problem to develop a detailed molecular mechanism to describe the process that leads to amplification of the Ub signal. A battery of solution-state NMR methods and molecular dynamics simulations were used to demonstrate that RAP80-tUIM employs mono- and multivalent interactions with polyUb chains to achieve enhanced affinity in comparison to monoUb interactions for signal amplification. The enhanced affinity is balanced by unfavorable entropic effects that include partial quenching of rapid reorientation between individual UIM domains and individual Ub domains in the bound state. For the RAP80-tUIM-polyUb interaction, increases in affinity with increasing chain length are a result of increased numbers of mono- and multivalent binding sites in the longer polyUb chains. The mono- and multivalent interactions are characterized by intrinsically weak binding and fast off-rates; these weak interactions with fast kinetics may be an important factor underlying the transient nature of protein-protein interactions that comprise DNA damage foci.

Determination of 15 N-nitrosodimethylamine precursors in different water matrices by automated on-line solid-phase extraction ultra-high-performance-liquid chromatography tandem mass spectrometry.

PubMed

Farré, Maria José; Insa, Sara; Mamo, Julian; Barceló, Damià

2016-08-05

A new methodology based on on-line solid-phase extraction (SPE) ultra-high-performance-liquid chromatography coupled to a triple quadrupole mass spectrometer (UHPLC-MS-MS) for the determination of 15 individual anthropogenic N-nitrosodimethylamine (NDMA) precursors was developed. On-line SPE was performed by passing 2mL of the water sample through a Hypersil GOLD aQ column and chromatographic separation was done using a Kinetex Biphenyl column using methanol and 0.1% formic acid aqueous solution as a mobile phase. For unequivocal identification and confirmation, two selected reaction monitoring (SRM) transitions were monitored per compound. Quantification was performed by internal standard approach and matrix match calibration. The main advantages of the developed method are high sensitivity (limits of detection in the sub ng/L range), selectivity due to the use of tandem mass spectrometry, precision and minimum sample manipulation as well as fast analytical response. Process efficiency and recovery were also evaluated for all the target compounds. As part of the validation procedure, the method was applied in a sampling campaign for the analysis of influent and secondary effluent of a wastewater treatment plant (WWTP) in Girona, Spain. Additionally, the effluent from a nanofiltration (NF) membrane system used for water recycling was monitored. The percentage of NDMA formation explained by the measured precursors was also quantified. Copyright © 2016 Elsevier B.V. All rights reserved.

Ligand Binding to WW Tandem Domains of YAP2 Transcriptional Regulator Is Under Negative Cooperativity

PubMed Central

Schuchardt, Brett J.; Mikles, David C.; Hoang, Lawrence M.; Bhat, Vikas; McDonald, Caleb B.; Sudol, Marius; Farooq, Amjad

2014-01-01

YAP2 transcriptional regulator drives a multitude of cellular processes, including the newly discovered Hippo tumor suppressor pathway, by virtue of the ability of its WW domains to bind and recruit PPXY-containing ligands to specific subcellular compartments. Herein, we employ an array of biophysical tools to investigate allosteric communication between the WW tandem domains of YAP2. Our data show that the WW tandem domains of YAP2 negatively cooperate when binding to their cognate ligands. Moreover, the molecular origin of such negative cooperativity lies in an unfavorable entropic contribution to the overall free energy relative to ligand binding to isolated WW domains. Consistent with this notion, the WW tandem domains adopt a fixed spatial orientation such that the WW1 domain curves outwards and stacks onto the binding groove of WW2 domain, thereby sterically hindering ligand binding to both itself and its tandem partner. Although ligand binding to both WW domains disrupts such interdomain stacking interaction, they reorient themselves and adopt an alternative fixed spatial orientation in the liganded state by virtue of their ability to engage laterally so as to allow their binding grooves to point outwards and away from each other. In short, while the ability of WW tandem domains to aid ligand binding is well-documented, our demonstration that they may also be subject to negative binding cooperativity represents a paradigm shift in our understanding of the molecular action of this ubiquitous family of protein modules. PMID:25283809

Interaction between synthetic analogues of quinoxaline antibiotics and nucleic acids: role of the disulphide cross-bridge and D-amino acid centres in des-N-tetramethyl-triostin A.

PubMed Central

Fox, K. R.; Olsen, R. K.; Waring, M. J.

1980-01-01

1 [Ala3, Ala7] TANDEM is an analogue of des-N-tetramethyl-triostin A (TANDEM) in which both L-Cys residues of the octapeptide ring are replaced by L-Ala; accordingly it lacks the disulphide cross-bridge which limits the conformational flexibility of TANDEM. 2 In [L-Ser1] TANDEM the configuration of one of the serine residues is inverted, altering the disposition of one of the quinoxaline chromophores with respect to the peptide ring. 3 Both compounds interact weakly but detectably with natural DNAs as judged by spectral shifts and increases in the thermal denaturation ('melting') temperature Tm. They also raise the Tm of poly rA . poly rU. 4 Binding isotherms determined by solvent partition analysis with [Ala3, Ala7] TANDEM yield association constants of about 10(3) M-1 for its interaction with natural DNAs. A Scatchard plot for binding to poly(dA-dT) determined by solvent partition and spectrophotometric methods shows marked evidence of cooperativity with an intrinsic association constant 1.9 x 10(4) M-1, 8.7 nucleotides per binding site, and cooperativity parameter 15. 5 Binding of [Ala3, Ala7] TANDEM to short rod-like fragments of poly(dA-dT) increases their contour length by almost the theoretical amount expected for an ideal process of bifunctional intercalation. 6 No effect of either compound on the winding of the DNA helix could be detected in sedimentation experiments with closed circular duplex PM2 DNA. 7 It is concluded that the cross-bridge of TANDEM greatly stabilizes its binding to DNA, most probably via entropic factors, but is not the only structural feature that influences its AT sequence-selectivity. The consequences of epimerising one of the D-Ser residues appear as disastrous as epimerising both. 8 The experimental details for the synthesis of [Ala3, Ala7] TANDEM and [L-Ser1] TANDEM are given in an appendix to this paper. PMID:7426829

Speed versus accuracy in decision-making ants: expediting politics and policy implementation.

PubMed

Franks, Nigel R; Dechaume-Moncharmont, François-Xavier; Hanmore, Emma; Reynolds, Jocelyn K

2009-03-27

Compromises between speed and accuracy are seemingly inevitable in decision-making when accuracy depends on time-consuming information gathering. In collective decision-making, such compromises are especially likely because information is shared to determine corporate policy. This political process will also take time. Speed-accuracy trade-offs occur among house-hunting rock ants, Temnothorax albipennis. A key aspect of their decision-making is quorum sensing in a potential new nest. Finding a sufficient number of nest-mates, i.e. a quorum threshold (QT), in a potential nest site indicates that many ants find it suitable. Quorum sensing collates information. However, the QT is also used as a switch, from recruitment of nest-mates to their new home by slow tandem running, to recruitment by carrying, which is three times faster. Although tandem running is slow, it effectively enables one successful ant to lead and teach another the route between the nests. Tandem running creates positive feedback; more and more ants are shown the way, as tandem followers become, in turn, tandem leaders. The resulting corps of trained ants can then quickly carry their nest-mates; but carried ants do not learn the route. Therefore, the QT seems to set both the amount of information gathered and the speed of the emigration. Low QTs might cause more errors and a slower emigration--the worst possible outcome. This possible paradox of quick decisions leading to slow implementation might be resolved if the ants could deploy another positive-feedback recruitment process when they have used a low QT. Reverse tandem runs occur after carrying has begun and lead ants back from the new nest to the old one. Here we show experimentally that reverse tandem runs can bring lost scouts into an active role in emigrations and can help to maintain high-speed emigrations. Thus, in rock ants, although quick decision-making and rapid implementation of choices are initially in opposition, a third recruitment method can restore rapid implementation after a snap decision. This work reveals a principle of widespread importance: the dynamics of collective decision-making (i.e. the politics) and the dynamics of policy implementation are sometimes intertwined, and only by analysing the mechanisms of both can we understand certain forms of adaptive organization.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Yusung, E-mail: yusung-kim@uiowa.edu; Muruganandham, Manickam; Modrick, Joseph M.

Purpose: The aim of this study was to characterize the levels of artifacts and distortions of titanium applicators on 3.0-Tesla magnetic resonance imaging (MRI). Methods and Materials: Fletcher-Suit-Delclos-style tandem and ovoids (T and O) and tandem and ring applicator (T and R) were examined. The quality assurance (QA) phantoms for each applicator were designed and filled with copper sulphate solution (1.5 g/l). The artifacts were quantified with the registration of corresponding computed tomography (CT) images. A favorable MR sequence was searched in terms of artifacts. Using the sequence, the artifacts were determined. The geometric distortions induced by the applicators weremore » quantified through each registration of CT and MRI without applicators. The artifacts of T and O were also evaluated on in vivo MRI datasets of 5 patients. Results: T1-weighted MRI with 1-mm slice thickness was found as a favorable MR sequence. Applying the sequence, the artifacts at the tandem tip of T and O and T and R were determined as 1.5 {+-} 0.5 mm in a superior direction in phantom studies. In the ovoids of T and O, we found artifacts less than 1.5 {+-} 0.5 mm. The artifacts of a T and O tandem in vivo were found as less than 2.6 {+-} 1.3 mm on T1-weighted MRI, whereas less than 6.9 {+-} 3.4 mm on T2-weighted MRI. No more than 1.2 {+-} 0.6 mm (3.0 {+-} 1.5 mm) of distortions, due to a titanium applicator, were measured on T1-weighted MRI (T2-). Conclusion: In 3.0-Tesla MRI, we found the artifact widths at the tip of tandem were less than 1.5 {+-} 0.5 mm for both T and O and T and R when using T1-weighted MRI in phantom studies. However, exclusive 3.0-Tesla MRI-guided brachytherapy planning with a titanium applicator should be cautiously implemented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zweifel,M.; Leahy, D.; Barrick, D.

Deltex is a cytosolic effector of Notch signaling thought to bind through its N-terminal domain to the Notch receptor. Here we report the structure of the Drosophila Deltex N-terminal domain, which contains two tandem WWE sequence repeats. The WWE repeats, which adopt a novel fold, are related by an approximate two-fold axis of rotation. Although the WWE repeats are structurally distinct, they interact extensively and form a deep cleft at their junction that appears well suited for ligand binding. The two repeats are thermodynamically coupled; this coupling is mediated in part by a conserved segment that is immediately C-terminal tomore » the second WWE domain. We demonstrate that although the Deltex WWE tandem is monomeric in solution, it forms a heterodimer with the ankyrin domain of the Notch receptor. These results provide structural and functional insight into how Deltex modulates Notch signaling, and how WWE modules recognize targets for ubiquitination.« less

Analysis of bromate in drinking water using liquid chromatography-tandem mass spectrometry without sample pretreatment.

PubMed

Kosaka, Koji; Asami, Mari; Takei, Kanako; Akiba, Michihiro

2011-01-01

An analytical method for determining bromate in drinking water was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The (18)O-enriched bromate was used as an internal standard. The limit of quantification (LOQ) of bromate was 0.2 µg/L. The peak of bromate was separated from those of coexisting ions (i.e., chloride, nitrate and sulfate). The relative and absolute recoveries of bromate in two drinking water samples and in a synthesized ion solution (100 mg/L chloride, 10 mg N/L nitrate, and 100 mg/L sulfate) were 99-105 and 94-105%, respectively. Bromate concentrations in 11 drinking water samples determined by LC-MS/MS were <0.2-2.3 µg/L. The results of the present study indicated that the proposed method was suitable for determining bromate concentrations in drinking water without sample pretreatment.

Determination of albendazole sulfoxide in human plasma by using liquid chromatography-tandem mass spectrometry.

PubMed

Saraner, Nihal; Özkan, Güler Yağmur; Güney, Berrak; Alkan, Erkin; Burul-Bozkurt, Nihan; Sağlam, Onursal; Fikirdeşici, Ezgi; Yıldırım, Mevlüt

2016-06-01

A rapid, simple and sensitive method was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of albendazole sulfoxide (ABZOX) in human plasma. The plasma samples were extracted by protein precipitation using albendazole sulfoxide-d3 as internal standard (IS). The chromatographic separation was performed on Waters Xbridge C18Column (100×4.6mm, 3.5μm) with a mobile phase consisting of ammonia solution, water and methanol at a flow rate of 0.70mL/min. ABZOX was detected and identified by mass spectrometry with electrospray ionization (ESI) in positive ion and multiple-reaction monitoring (MRM) mode. The method was linear in the range of 3-1500ng/mL for ABZOX. This method was successfully applied to the bioequivalence study in human plasma samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of chlorinated acid herbicides in vegetation and soil by liquid chromatography/electrospray-tandem mass spectrometry.

PubMed

Schaner, Angela; Konecny, Jaclyn; Luckey, Laura; Hickes, Heidi

2007-01-01

The method presented uses reversed-phase liquid chromatography with negative electrospray ionization and tandem mass spectrometry to analyze 9 chlorinated acid herbicides in soil and vegetation matrixes: clopyralid, dicamba, MCPP, MCPA, 2,4-DP, 2,4-D, triclopyr, 2,4-DB, and picloram. A 20 g portion is extracted with a basic solution and an aliquot acidified and micropartitioned with 3 mL chloroform. Vegetation samples are subjected to an additional cleanup with a mixed-mode anion exchange solid-phase extraction cartridge. Two precursor product ion transitions per analyte are measured and evaluated to provide the maximum degree of confidence in results. Average recoveries for 3 different soil types tested ranged from 72 to 107% for all compounds with the exception of 2,4-DB at 56-99%. Average recoveries for the 3 different vegetation types studied were lower and ranged from 53 to 80% for all compounds.

Tandem array of nanoelectronic readers embedded coplanar to a fluidic nanochannel for correlated single biopolymer analysis

PubMed Central

Lesser-Rojas, Leonardo; Sriram, K. K.; Liao, Kuo-Tang; Lai, Shui-Chin; Kuo, Pai-Chia; Chu, Ming-Lee; Chou, Chia-Fu

2014-01-01

We have developed a two-step electron-beam lithography process to fabricate a tandem array of three pairs of tip-like gold nanoelectronic detectors with electrode gap size as small as 9 nm, embedded in a coplanar fashion to 60 nm deep, 100 nm wide, and up to 150 μm long nanochannels coupled to a world-micro-nanofluidic interface for easy sample introduction. Experimental tests with a sealed device using DNA-protein complexes demonstrate the coplanarity of the nanoelectrodes to the nanochannel surface. Further, this device could improve transverse current detection by correlated time-of-flight measurements of translocating samples, and serve as an autocalibrated velocimeter and nanoscale tandem Coulter counters for single molecule analysis of heterogeneous samples. PMID:24753731

[Simultaneous determination of pyraclostrobin and thiophanate-methyl and its metabolite carbendazim residues in soil and citrus by QuEChERS-liquid chromatography- tandem mass spectrometry].

PubMed

Li, Fuqin; Shi, Lihong; Wang, Fei; Sun, Caiyuan; Kang, Di; Zhang, Yuping; Chen, Lingzhu; Hu, Deyu

2017-06-08

A QuEChERS-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of pyraclostrobin, thiophanate-methyl and its metabolite carbendazim in soil and citrus. The samples were extracted with methanol or acetonitrile, purified by primary secondary amine (PSA), then separated by LC, detected in multiple reaction monitoring (MRM) mass spectrometry mode via positive electrospray ionization. The analytes were quantified by matrix-matched standard solutions with external standard method. The limits of quantification (LOQs) of pyraclostrobin, thiophanate-methyl and carbendazim in different matrices were 5.8-7.0 μg/kg, 9.3-14.1 μg/kg and 2.1-2.6 μg/kg, respectively. For all the samples, the spiked recoveries ranged from 75.48% to 109.18%, and the relative standard deviations (RSDs) were 0.60%-5.11% ( n =5). The method is quick, easy, effective, sensitive and accurate. The matrix-matched calibration solutions can efficiently compensate matrix effects of the pyraclostrobin, thiophanate-methyl and carbendazim in LC-MS/MS analysis. The established method can be applied to the residue analysis of the real samples of soil, citrus peel, citrus pulp and citrus fruits.

Determination of a metabolite of nifursol in foodstuffs of animal origin by liquid-liquid extraction and liquid chromatography with tandem mass spectrometry.

PubMed

Wang, Chuanxian; Qu, Li; Liu, Xia; Zhao, Chaomin; Zhao, Fengjuan; Huang, Fuzhen; Zhu, Zhenou; Han, Chao

2017-02-01

An analytical method has been developed for the detection of a metabolite of nifursol, 3,5-dinitrosalicylic acid hydrazide, in foodstuffs of animal origin (chicken liver, pork liver, lobster, shrimp, eel, sausage, and honey). The method combines liquid chromatography and tandem mass spectrometry with liquid-liquid extraction. Samples were hydrolyzed with hydrochloric acid and derivatized with 2-nitrobenzaldehyde at 37°C for 16 h. The solutions of derivatives were adjusted to pH 7.0-7.5, and the metabolite was extracted with ethyl acetate. 3,5-Dinitrosalicylic acid hydrazide determination was performed in the negative electrospray ionization method. Both isotope-labeled internal standard and matrix-matched calibration solutions were used to correct the matrix effects. Limits of quantification were 0.5 μg/kg for all samples. The average recoveries, measured at three concentration levels (0.5, 2.0, and 10 μg/kg) were in the range of 75.8-108.4% with relative standard deviations below 9.8%. The developed method exhibits a high sensitivity and selectivity for the routine determination and confirmation of the presence of a metabolite of nifursol in foodstuffs of animal origin. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple and sensitive monitoring of β2-agonist residues in meat by liquid chromatography-tandem mass spectrometry using a QuEChERS with preconcentration as the sample treatment.

PubMed

Xiong, Lin; Gao, Ya-Qin; Li, Wei-Hong; Yang, Xiao-Lin; Shimo, Shimo Peter

2015-07-01

A liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method was established for the simultaneous determination of the levels of 10 β2-agonists in meat. The samples were extracted using an aqueous acidic solution and cleaned up using a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) technique utilising a DVB-NVP-SO3Na sorbent synthesised in-house. First, the β2-agonist residues were extracted in an aqueous acidic solution, followed by matrix solid-phase dispersion for clean-up. The linearities of the method were R(2)=0.9925-0.9998, with RSDs of 2.7-15.3% and 73.7-103.5% recoveries. Very low limits of detection (LOD) and quantitation (LOQ) of 0.2-0.9 μg/kg and 0.8-3.2 μg/kg, respectively, were achieved for spiked meat. The values obtained were lower than the maximum residue limits (MRLs) established by the EU and China. These results clearly demonstrate the feasibility of the proposed approach. The evaluated method provided reliable screening, quantification and identification of 10 β2-agonists in meat. Copyright © 2015 Elsevier Ltd. All rights reserved.

Laser mass spectrometry for DNA fingerprinting for forensic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.H.; Tang, K.; Taranenko, N.I.

The application of DNA fingerprinting has become very broad in forensic analysis, patient identification, diagnostic medicine, and wildlife poaching, since every individual`s DNA structure is identical within all tissues of their body. DNA fingerprinting was initiated by the use of restriction fragment length polymorphisms (RFLP). In 1987, Nakamura et al. found that a variable number of tandem repeats (VNTR) often occurred in the alleles. The probability of different individuals having the same number of tandem repeats in several different alleles is very low. Thus, the identification of VNTR from genomic DNA became a very reliable method for identification of individuals.more » DNA fingerprinting is a reliable tool for forensic analysis. In DNA fingerprinting, knowledge of the sequence of tandem repeats and restriction endonuclease sites can provide the basis for identification. The major steps for conventional DNA fingerprinting include (1) specimen processing (2) amplification of selected DNA segments by PCR, and (3) gel electrophoresis to do the final DNA analysis. In this work we propose to use laser desorption mass spectrometry for fast DNA fingerprinting. The process and advantages are discussed.« less

Asymmetric allylation of ketones and subsequent tandem reactions catalyzed by a novel polymer-supported titanium-BINOLate complex.

PubMed

Yadav, Jagjit; Stanton, Gretchen R; Fan, Xinyuan; Robinson, Jerome R; Schelter, Eric J; Walsh, Patrick J; Pericas, Miquel A

2014-06-02

By using a novel, simple, and convenient synthetic route, enantiopure 6-ethynyl-BINOL (BINOL = 1,1-binaphthol) was synthesized and anchored to an azidomethylpolystyrene resin through a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The polystyrene (PS)-supported BINOL ligand was converted into its diisopropoxytitanium derivative in situ and used as a heterogeneous catalyst in the asymmetric allylation of ketones. The catalyst showed good activity and excellent enantioselectivity, typically matching the results obtained in the corresponding homogeneous reaction. The allylation reaction mixture could be submitted to epoxidation by simple treatment with tert-butyl hydroperoxide (TBHP), and the tandem asymmetric allylation epoxidation process led to a highly enantioenriched epoxy alcohol with two adjacent quaternary centers as a single diastereomer. A tandem asymmetric allylation/Pauson-Khand reaction was also performed, involving simple treatment of the allylation reaction mixture with Co2(CO)8/N-methyl morpholine N-oxide. This cascade process resulted in the formation of two diastereomeric tricyclic enones in high yields and enantioselectivities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stable low-bandgap Pb-Sn binary perovskites for tandem solar cells

DOE PAGES

Yang, Zhibin; Rajagopal, Adharsh; Chueh, Chu -Chen; ...

2016-08-22

A low-bandgap (1.33 eV) Sn-based MA 0.5FA 0.5Pb 0.75Sn 0.25I 3 perovskite is developed via combined compositional, process, and interfacial engineering. It can deliver a high power conversion efficiency (PCE) of 14.19%. Lastly, a four-terminal all-perovskite tandem solar cell is demonstrated by combining this low-bandgap cell with a semitransparent MAPbI 3 cell to achieve a high efficiency of 19.08%.

Ranked solutions to a class of combinatorial optimizations - with applications in mass spectrometry based peptide sequencing

NASA Astrophysics Data System (ADS)

Doerr, Timothy; Alves, Gelio; Yu, Yi-Kuo

2006-03-01

Typical combinatorial optimizations are NP-hard; however, for a particular class of cost functions the corresponding combinatorial optimizations can be solved in polynomial time. This suggests a way to efficiently find approximate solutions - - find a transformation that makes the cost function as similar as possible to that of the solvable class. After keeping many high-ranking solutions using the approximate cost function, one may then re-assess these solutions with the full cost function to find the best approximate solution. Under this approach, it is important to be able to assess the quality of the solutions obtained, e.g., by finding the true ranking of kth best approximate solution when all possible solutions are considered exhaustively. To tackle this statistical issue, we provide a systematic method starting with a scaling function generated from the fininte number of high- ranking solutions followed by a convergent iterative mapping. This method, useful in a variant of the directed paths in random media problem proposed here, can also provide a statistical significance assessment for one of the most important proteomic tasks - - peptide sequencing using tandem mass spectrometry data.

[Simultaneous determination of four alkaloids in Corydalis decumbens (Thunb.) Pers. by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Shen, Yan; Han, Chao; Liu, Cuiping; Zhou, Yongfang; Xia, Biqi; Zhu, Zhenou; Liu, Aili

2011-02-01

A method for the analysis of 4 alkaloids in Corydalis decumbens (Thunb.) Pers. was developed by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS). The sample was extracted in methanol by ultrasonic, filtered and diluted with methanol for further analysis. The analysis was performed on a C18 column (150 mm x 2.1 mm, 3.5 microm) using a gradient elution program with the mobile phase of 0.2% acetic acid solution and acetonitrile. The analyte was determined by an electrospray ionization tandem mass spectrometry in multiple reactions monitoring (MRM) mode. The qualitative and quantitative analyses were based on the retention times and characteristic ion pairs consisting of one parent ion and two fragment ions of the analyte. The limits of detection (LODs) for 4 alkaloids were in the range of 0.02 - 0.2 microg/L, and the limits of quantification (LOQs) were in the range of 0.07 - 0.66 microg/L. The average recoveries were in the range of 93.6% - 103.5% for 4 alkaloids with the relative standard deviations below 3.8%. This method is reliable, sensitive and reproducible, and it can be used for the quality control of Corydalis decumbens (Thunb.) Pers. sample.

Identification of Poly(ethylene glycol) and Poly(ethylene glycol)-Based Detergents Using Peptide Search Engines.

PubMed

Ahmadi, Shiva; Winter, Dominic

2018-06-05

Poly(ethylene glycol) (PEG) is one of the most common polymer contaminations in mass spectrometry (MS) samples. At present, the detection of PEG and other polymers relies largely on manual inspection of raw data, which is laborious and frequently difficult due to sample complexity and retention characteristics of polymer species in reversed-phase chromatography. We developed a new strategy for the automated identification of PEG molecules from tandem mass spectrometry (MS/MS) data using protein identification algorithms in combination with a database containing "PEG-proteins". Through definition of variable modifications, we extend the approach for the identification of commonly used PEG-based detergents. We exemplify the identification of different types of polymers by static nanoelectrospray tandem mass spectrometry (nanoESI-MS/MS) analysis of pure detergent solutions and data analysis using Mascot. Analysis of liquid chromatography-tandem mass spectrometry (LC-MS/MS) runs of a PEG-contaminated sample by Mascot identified 806 PEG spectra originating from four PEG species using a defined set of modifications covering PEG and common PEG-based detergents. Further characterization of the sample for unidentified PEG species using error-tolerant and mass-tolerant searches resulted in identification of 3409 and 3187 PEG-related MS/MS spectra, respectively. We further demonstrate the applicability of the strategy for Protein Pilot and MaxQuant.

Quantitative Protein Topography Analysis and High-Resolution Structure Prediction Using Hydroxyl Radical Labeling and Tandem-Ion Mass Spectrometry (MS)*

PubMed Central

Kaur, Parminder; Kiselar, Janna; Yang, Sichun; Chance, Mark R.

2015-01-01

Hydroxyl radical footprinting based MS for protein structure assessment has the goal of understanding ligand induced conformational changes and macromolecular interactions, for example, protein tertiary and quaternary structure, but the structural resolution provided by typical peptide-level quantification is limiting. In this work, we present experimental strategies using tandem-MS fragmentation to increase the spatial resolution of the technique to the single residue level to provide a high precision tool for molecular biophysics research. Overall, in this study we demonstrated an eightfold increase in structural resolution compared with peptide level assessments. In addition, to provide a quantitative analysis of residue based solvent accessibility and protein topography as a basis for high-resolution structure prediction; we illustrate strategies of data transformation using the relative reactivity of side chains as a normalization strategy and predict side-chain surface area from the footprinting data. We tested the methods by examination of Ca+2-calmodulin showing highly significant correlations between surface area and side-chain contact predictions for individual side chains and the crystal structure. Tandem ion based hydroxyl radical footprinting-MS provides quantitative high-resolution protein topology information in solution that can fill existing gaps in structure determination for large proteins and macromolecular complexes. PMID:25687570

Intramolecular trimerization, a novel strategy for making multispecific antibodies with controlled orientation of the antigen binding domains

PubMed Central

Alvarez-Cienfuegos, Ana; Nuñez-Prado, Natalia; Compte, Marta; Cuesta, Angel M.; Blanco-Toribio, Ana; Harwood, Seandean Lykke; Villate, Maider; Merino, Nekane; Bonet, Jaume; Navarro, Rocio; Muñoz-Briones, Clara; Sørensen, Karen Marie Juul; Mølgaard, Kasper; Oliva, Baldo; Sanz, Laura; Blanco, Francisco J.; Alvarez-Vallina, Luis

2016-01-01

Here, we describe a new strategy that allows the rapid and efficient engineering of mono and multispecific trivalent antibodies. By fusing single-domain antibodies from camelid heavy-chain-only immunoglobulins (VHHs) to the N-terminus of a human collagen XVIII trimerization domain (TIEXVIII) we produced monospecific trimerbodies that were efficiently secreted as soluble functional proteins by mammalian cells. The purified VHH-TIEXVIII trimerbodies were trimeric in solution and exhibited excellent antigen binding capacity. Furthermore, by connecting with two additional glycine-serine-based linkers three VHH-TIEXVIII modules on a single polypeptide chain, we present an approach for the rational design of multispecific tandem trimerbodies with defined stoichiometry and controlled orientation. Using this technology we report here the construction and characterization of a tandem VHH-based trimerbody capable of simultaneously binding to three different antigens: carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR) and green fluorescence protein (GFP). Multispecific tandem VHH-based trimerbodies were well expressed in mammalian cells, had good biophysical properties and were capable of simultaneously binding their targeted antigens. Importantly, these antibodies were very effective in inhibiting the proliferation of human epidermoid carcinoma A431 cells. Multispecific VHH-based trimerbodies are therefore ideal candidates for future applications in various therapeutic areas. PMID:27345490

Three-dimensional photonic crystals as intermediate filter for thin-film tandem solar cells

NASA Astrophysics Data System (ADS)

Bielawny, Andreas; Miclea, Paul T.; Wehrspohn, Ralf B.; Lee, Seung-Mo; Knez, Mato; Rockstuhl, Carsten; Lisca, Marian; Lederer, Falk L.; Carius, Reinhard

2008-04-01

The concept of a 3D photonic crystal structure as diffractive and spectrally selective intermediate filter within 'micromorphous' (a-Si/μc-Si) tandem solar cells has been investigated numerically and experimentally. Our device aims for the enhancement of the optical pathway of incident light within the amorphous silicon top cell in its spectral region of low absorption. From our previous simulations, we expect a significant improvement of the tandem cell efficiency of about absolutely 1.3%. This increases the efficiency for a typical a-Si / μc-Si tandem cell from 11.1% to 12.4%, as a result of the optical current-matching of the two junctions. We suggest as wavelength-selective optical element a 3D-structured optical thin-film, prepared by self-organized artificial opal templates and replicated with atomic layer deposition. The resulting samples are highly periodic thin-film inverted opals made of conducting and transparent zinc-oxide. We describe the fabrication processes and compare experimental data on the optical properties in reflection and transmission with our simulations and photonic band structure calculations.

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

PubMed Central

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

2011-01-01

According to the structure of podophyllotoxin and its structure-function relationship, a novel tandem biotransformation process was developed for the directional modification of the podophyllotoxin structure to directionally synthesize a novel compound, 4-(2,3,5,6-tetramethylpyrazine-1)-4′-demethylepipodophyllotoxin (4-TMP-DMEP). In this novel tandem biotransformation process, the starting substrate of podophyllotoxin was biotransformed into 4′-demethylepipodophyllotoxin (product 1) with the demethylation of the methoxyl group at the 4′ position by Gibberella fujikuroi SH-f13, which was screened out from Shennongjia prime forest humus soil (Hubei, China). 4′-Demethylepipodophyllotoxin (product 1) was then biotransformed into 4′-demethylpodophyllotoxone (product 2) with the oxidation of the hydroxyl group at the 4 position by Alternaria alternata S-f6, which was screened out from the gathered Dysosma versipellis plants in the Wuhan Botanical Garden, Chinese Academy of Sciences. Finally, 4′-demethylpodophyllotoxone (product 2) and ligustrazine were linked with a transamination reaction to synthesize the target product 4-TMP-DMEP (product 3) by Alternaria alternata S-f6. Compared with podophyllotoxin (i.e., a 50% effective concentration [EC50] of 529 μM), the EC50 of 4-TMP-DMEP against the tumor cell line BGC-823 (i.e., 0.11 μM) was significantly reduced by 5,199 times. Simultaneously, the EC50 of 4-TMP-DMEP against the normal human proximal tubular epithelial cell line HK-2 (i.e., 0.40 μM) was 66 times higher than that of podophyllotoxin (i.e., 0.006 μM). Furthermore, compared with podophyllotoxin (i.e., log P = 0.34), the water solubility of 4-TMP-DMEP (i.e., log P = 0.66) was significantly enhanced by 94%. For the first time, the novel compound 4-TMP-DMEP with superior antitumor activity was directionally synthesized from podophyllotoxin by the novel tandem biotransformation process developed in this work. PMID:21398491

On the tandem Morita-Baylis-Hillman/transesterification processes. Mechanistic insights for the role of protic solvents

NASA Astrophysics Data System (ADS)

Carpanez, Arthur G.; Coelho, Fernando; Amarante, Giovanni W.

2018-02-01

Despite the remarkable rate acceleration under protic solvents such as alcohols and water, the use of acrylates as activated alkenes places a problem due to the possibility of ester hydrolysis or transesterification. Therefore, the tandem transesterification/Morita-Baylis-Hillman (MBH) reactions were investigated by ESI(+)-MS/(MS) and 1H NMR techniques. For the first time, the MBH back-reaction was fully examined by ESI(+)-MS/(MS) using labelling reagents revealed the complex equilibrium involving the Michael-type addition step of DABCO to acrylate. C- and O-protonation were observed at this stage, showing the transesterification process occurs previous to the aldol step, which is the rate-determining step of the mechanism. At this stage, a short-lived tetrahedral intermediate might be involved and should be considered in these processes.

Study on the reactive transient α-λ3-iodanyl-acetophenone complex in the iodine(III)/PhI(I) catalytic cycle of iodobenzene-catalyzed α-acetoxylation reaction of acetophenone by electrospray ionization tandem mass spectrometry.

PubMed

Wang, Hao-Yang; Zhou, Juan; Guo, Yin-Long

2012-03-30

Hypervalent iodine compounds are important and widely used oxidants in organic chemistry. In 2005, Ochiai reported the PhI-catalyzed α-acetoxylation reaction of acetophenone by the oxidation of PhI with m-chloroperbenzoic acid (m-CPBA) in acetic acid. However, until now, the most critical reactive α-λ(3)-iodine alkyl acetophenone intermediate (3) had not been isolated or directly detected. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the transient reactive α-λ(3)-iodine alkyl acetophenone intermediate in the reaction solution. The trivalent iodine species was detected when PhI and m-CPBA in acetic acid were mixed, which indicated the facile oxidation of a catalytic amount of PhI(I) to the iodine(III) species by m-CPBA. Most importantly, 3·H(+) was observed at m/z 383 from the reaction solution and this ion gave the protonated α-acetoxylation product 4·H(+) at m/z 179 in MS/MS by an intramolecular reductive elimination of PhI. These ESI-MS/MS studies showed the existence of the reactive α-λ(3)-iodine alkyl acetophenone intermediate 3 in the catalytic cycle. Moreover, the gas-phase reactivity of 3·H(+) was consistent with the proposed solution-phase reactivity of the α-λ(3)-iodine alkyl acetophenone intermediate 3, thus confirming the reaction mechanism proposed by Ochiai. Copyright © 2012 John Wiley & Sons, Ltd.

Ligand binding to WW tandem domains of YAP2 transcriptional regulator is under negative cooperativity.

PubMed

Schuchardt, Brett J; Mikles, David C; Hoang, Lawrence M; Bhat, Vikas; McDonald, Caleb B; Sudol, Marius; Farooq, Amjad

2014-12-01

YES-associated protein 2 (YAP2) transcriptional regulator drives a multitude of cellular processes, including the newly discovered Hippo tumor suppressor pathway, by virtue of the ability of its WW domains to bind and recruit PPXY-containing ligands to specific subcellular compartments. Herein, we employ an array of biophysical tools to investigate allosteric communication between the WW tandem domains of YAP2. Our data show that the WW tandem domains of YAP2 negatively cooperate when binding to their cognate ligands. Moreover, the molecular origin of such negative cooperativity lies in an unfavorable entropic contribution to the overall free energy relative to ligand binding to isolated WW domains. Consistent with this notion, the WW tandem domains adopt a fixed spatial orientation such that the WW1 domain curves outwards and stacks onto the binding groove of the WW2 domain, thereby sterically hindering ligand binding to both itself and its tandem partner. Although ligand binding to both WW domains disrupts such interdomain stacking interaction, they reorient themselves and adopt an alternative fixed spatial orientation in the liganded state by virtue of their ability to engage laterally so as to allow their binding grooves to point outwards and away from each other. In short, while the ability of WW tandem domains to aid ligand binding is well documented, our demonstration that they may also be subject to negative binding cooperativity represents a paradigm shift in our understanding of the molecular action of this ubiquitous family of protein modules. © 2014 FEBS.

Modeling and designing multilayer 2D perovskite / silicon bifacial tandem photovoltaics for high efficiencies and long-term stability.

PubMed

Chung, Haejun; Sun, Xingshu; Mohite, Aditya D; Singh, Rahul; Kumar, Lokendra; Alam, Muhammad A; Bermel, Peter

2017-04-17

A key challenge in photovoltaics today is to develop cell technologies with both higher efficiencies and lower fabrication costs than incumbent crystalline silicon (c-Si) single-junction cells. While tandem cells have higher efficiencies than c-Si alone, it is generally challenging to find a low-cost, high-performance material to pair with c-Si. However, the recent emergence of 22% efficient perovskite photovoltaics has created a tremendous opportunity for high-performance, low-cost perovskite / crystalline silicon tandem photovoltaic cells. Nonetheless, two key challenges remain. First, integrating perovskites into tandem structures has not yet been demonstrated to yield performance exceeding commercially available crystalline silicon modules. Second, the stability of perovskites is inconsistent with the needs of most end-users, who install photovoltaic modules to produce power for 25 years or more. Making these cells viable thus requires innovation in materials processing, device design, fabrication, and yield. We will address these two gaps in the photovoltaic literature by investigating new types of 2D perovskite materials with n-butylammonium spacer layers, and integrating these materials into bifacial tandem solar cells providing at least 30% normalized power production. We find that an optimized 2D perovskite ((BA)₂(MA)₃(Sn_0.6Pb_0.4)₄I₁₃)/silicon bifacial tandem cell, given a globally average albedo of 30%, yields a normalized power production of 30.31%, which should be stable for extended time periods without further change in materials or encapsulation.

Non-Target Screening of Veterinary Drugs Using Tandem Mass Spectrometry on SmartMass

NASA Astrophysics Data System (ADS)

Xia, Bing; Liu, Xin; Gu, Yu-Cheng; Zhang, Zhao-Hui; Wang, Hai-Yan; Ding, Li-Sheng; Zhou, Yan

2013-05-01

Non-target screening of veterinary drugs using tandem mass spectrometric data was performed on the SmartMass platform. This newly developed software uses the characteristic fragmentation patterns (CFP) to identify chemicals, especially those containing particular substructures. A mixture of 17 sulfonamides was separated by ultra performance liquid chromatography (UPLC), and SmartMass was used to process the tandem mass spectrometry (MS/MS) data acquired on an Orbitrap mass spectrometer. The data were automatically extracted, and each sulfonamide was recognized and analyzed with a prebuilt analysis rule. By using this software, over 98 % of the false candidate structures were eliminated, and all the correct structures were found within the top 10 of the ranking lists. Furthermore, SmartMass could also be used to identify slightly modified contraband drugs and metabolites with simple prebuilt rules. [Figure not available: see fulltext.

High Photoluminescence Quantum Yield in Band Gap Tunable Bromide Containing Mixed Halide Perovskites

DOE PAGES

Sutter-Fella, Carolin M.; Li, Yanbo; Amani, Matin; ...

2015-12-21

Hybrid organic-inorganic halide perovskite based semiconductor materials are attractive for use in a wide range of optoelectronic devices because they combine the advantages of suitable optoelectronic attributes and simultaneously low-cost solution processability. Here, we present a two-step low-pressure vapor-assisted solution process to grow high quality homogeneous CH 3NH 3PbI 3-xBr x perovskite films over the full band gap range of 1.6-2.3 eV. Photoluminescence light-in versus light-out characterization techniques are used to provide new insights into the optoelectronic properties of Br-containing hybrid organic-inorganic perovskites as a function of optical carrier injection by employing pump-powers over a 6 orders of magnitude dynamicmore » range. The internal luminescence quantum yield of wide band gap perovskites reaches impressive values up to 30%. This high quantum yield translates into substantial quasi-Fermi level splitting and high "luminescence or optically implied" open-circuit voltage. Most importantly, both attributes, high internal quantum yield and high optically implied open-circuit voltage, are demonstrated over the entire band gap range (1.6 eV ≤ E g ≤ 2.3 eV). These results establish the versatility of Br-containing perovskite semiconductors for a variety of applications and especially for the use as high-quality top cell in tandem photovoltaic devices in combination with industry dominant Si bottom cells. (Figure Presented).« less

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

PubMed

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

2011-04-26

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

Influence of N-type μc-SiOx:H intermediate reflector and top cell material properties on the electrical performance of "micromorph" tandem solar cells

NASA Astrophysics Data System (ADS)

Chatterjee, P.; Roca i Cabarrocas, P.

2018-01-01

Amorphous silicon (a-Si:H) / micro-crystalline silicon (μc-Si:H), "micromorph" tandem solar cells have been investigated using a detailed electrical - optical model. Although such a tandem has good light absorption over the entire visible spectrum, the a-Si:H top cell suffers from strong light-induced degradation (LID). To improve matters, we have replaced a-Si:H by hydrogenated polymorphous silicon (pm-Si:H), a nano-structured silicon thin film with lower LID than a-Si:H. But the latter's low current carrying capacity necessitates a thicker top cell for current-matching, again leading to LID problems. The solution is to introduce a suitable intermediate reflector (IR) at the junction between the sub-cells, to concentrate light of the shorter visible wavelengths into the top cell. Here we assess the suitability of N-type micro-crystalline silicon oxide (μc-SiOx:H) as an IR. The sensitivity of the solar cell performance to the complex refractive index, thickness and texture of such a reflector is studied. We conclude that N-μc-SiOx:H does concentrate light into the top sub-cell, thus reducing its required thickness for current-matching. However the IR also reflects light right out of the device; so that the initial efficiency suffers. The advantage of such an IR is ultimately seen in the stabilized state since the LID of a thin top cell is low. We also find that for high stabilized efficiencies, the IR should be flat (having no texture of its own). Our study indicates that we may expect to reach 15% stable tandem micromorph efficiency.

Solar hydrogen production by tandem cell system composed of metal oxide semiconductor film photoelectrode and dye-sensitized solar cell

NASA Astrophysics Data System (ADS)

Arakawa, H.; Shiraishi, C.; Tatemoto, M.; Kishida, H.; Usui, D.; Suma, A.; Takamisawa, A.; Yamaguchi, T.

2007-09-01

Photocatalytic and photoelectrochemical approaches to solar hydrogen production in our group were introduced. In photocatalytic water splitting system using NiO x/ TiO II powder photocatalyst with concentrated Na IICO 3 aqueous solution, solar energy conversion efficiency to H II and O II production (STH efficiency) was 0.016%. In addition, STH efficiency of visible light responding photocatalyst, NiOx/ promoted In 0.9Ni 0.1TaO 4, was estimated at 0.03%. In photoelectrochemical system using an oxide semiconductor film phptoelectrode, STH efficiencies of meosporous TiO II (Anatase) , mesoporous visible light responding S-doped TiO II (Anatase) and WO 3 film were 0.32-0.44% at applied potential of 0.35 V vs NHE, 0.14% at 0.55 V and 0.44% at 0.9 V, respectively. Finally, solar hydrogen production by tandem cell system composed of an oxide semiconductor photoelectrode, a Pt wire counter electrode and a dye-sensitized solar cell (DSC) was investigated. As photoelectrodes, meosporous TiO II (Anatase), mesoporous S-doped TiO II (Anatase), WO 3, BiVO 4 and Fe IIO 3 film were tested. STH efficiency of tandem cell system composed of a WO 3 film photoelectrode, and a two-series-connected DSC (Voc = 1.4 V) was 2.5-2.8%. In conclusion, it is speculated that more than 5% STH efficiency will be obtained by tandem cell system composed of an oxide semiconductor photoelectrode and a two-series-connected DSC in near future. This suggests a cost-effective and practical application of this system for solar hydrogen production.

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

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 3 2011-10-01 2011-10-01 false Tandem-switched transport and tandem charge. 69... SERVICES (CONTINUED) ACCESS CHARGES Computation of Charges § 69.111 Tandem-switched transport and tandem...-switched transport shall consist of two rate elements, a transmission charge and a tandem switching charge...

Direct Access to 2,3,4,6-Tetrasubstituted Tetrahydro-2H-pyrans via Tandem SN2'-Prins Cyclization.

PubMed

Scoccia, Jimena; Pérez, Sixto J; Sinka, Victoria; Cruz, Daniel A; López-Soria, Juan M; Fernández, Israel; Martín, Víctor S; Miranda, Pedro O; Padrón, Juan I

2017-09-15

A new, direct, and diastereoselective synthesis of activated 2,3,4,6-tetrasubstituted tetrahydro-2H-pyrans is described. In this reaction, iron(III) catalyzed an S N 2'-Prins cyclization tandem process leading to the creation of three new stereocenters in one single step. These activated tetrahydro-2H-pyran units are easily derivatizable through CuAAC conjugations in order to generate multifunctionalized complex molecules. DFT calculations support the in situ S N 2' reaction as a preliminary step in the Prins cyclization.

[Comprehensive implementation of interprofessional quality circles regarding early prevention of childhood disadvantage in Baden Württemberg (Germany)].

PubMed

Siebolds, Marcus; Münzel, Brigitte; Müller, Roland; Häußermann, Sigrun; Paul, Mechthild; Kahl, Cornelia

2016-10-01

The integration of available early interventions and healthcare for families with children by practicing pediatricians has yet to be systematically established. For this reason, the Association of Statutory Health Insurance Physicians of Baden-Wuerttemberg established overarching, accredited, cross-system quality circles that serve to integrate all representatives of the healthcare system as well as child and youth welfare services. These quality circles are led by specially trained moderator tandems consisting of pediatricians and staff members from youth welfare services. The goal was to evaluate the endpoints of the regional implementation of cross-system quality circles for early interventions in the state of Baden-Wuerttemberg as well as the feasibility of establishing long-term training programs for cross-system moderator tandems. This was a noncontrolled, longitudinal study to prepare a yearly evaluation of the quality-circle assessments as well as to gather statistics on the training of the moderator tandems within the Association of Statutory Health Insurance Physicians of Baden-Wuerttemberg. A total of 59 moderator tandems were trained in nine separate training sessions within the project period from 2011 to 2015. Overall, 33 quality circles were founded. In 2015, 566 persons were participating in the respective circles. Over the course of the study between 26 and 33 of the 44 urban and rural districts in the state of Baden-Wuerttemberg had at least one quality circle dedicated to early interventions. Ten further circles are presently in the process of being founded; 29 moderators have yet to commence their activity or have withdrawn from the program. Between 59 and 81 % of the urban and rural districts implemented cross-system quality circles. The training of the moderator tandems proceeded without complications. Because of the dropout quota of the trained moderator tandems, systematic and continual training of new tandems proves to be necessary.

Enhanced fill factor of tandem organic solar cells incorporating a diketopyrrolopyrrole-based low-bandgap polymer and optimized interlayer.

PubMed

Wang, Dong Hwan; Kyaw, Aung Ko Ko; Park, Jong Hyeok

2015-01-01

We demonstrate that reproducible results can be obtained from tandem solar cells based on the wide-bandgap poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and the diketopyrrolopyrrole (DPP)-based narrow bandgap polymer (DT-PDPP2T-TT) with a decyltetradecyl (DT) and an electron-rich 2,5-di-2-thienylthieno[3,2-b]thiophene (2T-TT) group fabricated using an optimized interlayer (ZnO NPs/ph-n-PEDOT:PSS) [NPs: nanoparticles; ph-n: pH-neutral PEDOT: poly(3,4-ethylenedioxythiophene); PSS: polystyrene sulfonate]. The tandem cells are fabricated by applying a simple process without thermal annealing. The ZnO NP interlayer operates well when the ZnO NPs are dispersed in 2-methoxyethanol, as no precipitation and chemical reactions occur. In addition to the ZnO NP film, we used neutral PEDOT:PSS as a second interlayer which is not affect to the sequential deposited bulk heterojunction (BHJ) active layer of acidification. The power conversion efficiency (PCE) of a tandem device reaches 7.4 % (open-circuit voltage VOC =1.53 V, short-circuit current density JSC =7.3 mA cm(-2) , and fill factor FF=67 %). Furthermore, FF is increased to up to 71 % when another promising large bandgap (bandgap ∼1.94 eV) polymer (PBnDT-FTAZ) is used. The surface of each layer with nanoscale morphology (BHJ1/ZnO NPs film/ph-n-PEDOT:PSS/BHJ2) was examined by means of AFM analysis during sequential processing. The combination of these factors, efficient DPP-based narrow bandgap material and optimized interlayer, leads to the high FF (average approaches 70 %) and reproducibly operating tandem BHJ solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cloud parallel processing of tandem mass spectrometry based proteomics data.

PubMed

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

2012-10-05

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

Solution-deposited F:SnO₂/TiO₂ as a base-stable protective layer and antireflective coating for microtextured buried-junction H₂-evolving Si photocathodes.

PubMed

Kast, Matthew G; Enman, Lisa J; Gurnon, Nicholas J; Nadarajah, Athavan; Boettcher, Shannon W

2014-12-24

Protecting Si photocathodes from corrosion is important for developing tandem water-splitting devices operating in basic media. We show that textured commercial Si-pn(+) photovoltaics protected by solution-processed semiconducting/conducting oxides (plausibly suitable for scalable manufacturing) and coupled to thin layers of Ir yield high-performance H2-evolving photocathodes in base. They also serve as excellent test structures to understand corrosion mechanisms and optimize interfacial electrical contacts between various functional layers. Solution-deposited TiO2 protects Si-pn(+) junctions from corrosion for ∼24 h in base, whereas junctions protected by F:SnO2 fail after only 1 h of electrochemical cycling. Interface layers consisting of Ti metal and/or the highly doped F:SnO2 between the Si and TiO2 reduce Si-emitter/oxide/catalyst contact resistance and thus increase fill factor and efficiency. Controlling the oxide thickness led to record photocurrents near 35 mA cm(-2) at 0 V vs RHE and photocathode efficiencies up to 10.9% in the best cells. Degradation, however, was not completely suppressed. We demonstrate that performance degrades by two mechanisms, (1) deposition of impurities onto the thin catalyst layers, even from high-purity base, and (2) catastrophic failure via pinholes in the oxide layers after several days of operation. These results provide insight into the design of hydrogen-evolving photoelectrodes in basic conditions, and highlight challenges.

Assigning Peptide Disulfide Linkage Pattern Among Regio-Isomers via Methoxy Addition to Disulfide and Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Durand, Kirt L.; Tan, Lei; Stinson, Craig A.; Love-Nkansah, Chasity B.; Ma, Xiaoxiao; Xia, Yu

2017-06-01

Pinpointing disulfide linkage pattern is critical in the characterization of proteins and peptides consisting of multiple disulfide bonds. Herein, we report a method based on coupling online disulfide modification and tandem mass spectrometry (MS/MS) to distinguish peptide disulfide regio-isomers. Such a method relies on a new disulfide bond cleavage reaction in solution, involving methanol as a reactant and 254 nm ultraviolet (UV) irradiation. This reaction leads to selective cleavage of a disulfide bond and formation of sulfenic methyl ester (-SOCH3) at one cysteine residue and a thiol (-SH) at the other. Under low energy collision-induced dissociation (CID), cysteine sulfenic methyl ester motif produces a signature methanol loss (-32 Da), allowing its identification from other possible isomeric structures such as S-hydroxylmethyl (-SCH2OH) and methyl sulfoxide (-S(O)-CH3). Since disulfide bond can be selectively cleaved and modified upon methoxy addition, subsequent MS2 CID of the methoxy addition product provides enhanced sequence coverage as demonstrated by the analysis of bovine insulin. More importantly, this reaction does not induce disulfide scrambling, likely due to the fact that radical intermediates are not involved in the process. An approach based on methoxy addition followed by MS3 CID has been developed for assigning disulfide linkage patterns in peptide disulfide regio-isomers. This methodology was successfully applied to characterizing peptide systems having two disulfide bonds and three disulfide linkage isomers: side-by-side, overlapped, and looped-within-a-loop configurations. [Figure not available: see fulltext.

Full Sputtering Deposition of Thin Film Solar Cells: A Way of Achieving High Efficiency Sustainable Tandem Cells?

NASA Astrophysics Data System (ADS)

Vilcot, J.-P.; Ayachi, B.; Aviles, T.; Miska, P.

2017-11-01

In the first part of this paper, we will show that a sputtering-based fabrication process exhibiting a low environmental footprint has been developed for the fabrication of copper indium gallium selenide (CIGS) absorbing material. Its originality lies in using room temperature sputtering in a pulsed—direct current mode of a single quaternary target followed by a post-anneal. At any stage of the process, selenium or sulfur atmosphere is used. Inert gas is used, respectively argon and a forming gas, for the deposition and annealing step, respectively. CIGS cells have been fabricated using such an absorbing layer. They exhibit an efficiency close to 12%. A tandem cell approach, using a thin film technology in conjunction with the well-established Si technology, is a promising technique, achieving cells with 30%, and higher, efficiency. Such cells are awaited, jointly with a stronger implementation of low environmental footprint technologies, as a vision for 2030. In the first section, sputtering technique has shown its ability to be developed in such a way achieving an environmentally friendly process that can be moreover compatible to be co-integrated with, for example, Si technology. In a second section, we will present a prospective discussion on the materials that can be applied to produce a sustainable approach for such a tandem cell configuration.

Within-Host Evolution of Burkholderia pseudomallei in Four Cases of Acute Melioidosis

PubMed Central

Limmathurotsakul, Direk; Max, Tamara L.; Sarovich, Derek S.; Vogler, Amy J.; Dale, Julia L.; Ginther, Jennifer L.; Leadem, Benjamin; Colman, Rebecca E.; Foster, Jeffrey T.; Tuanyok, Apichai; Wagner, David M.; Peacock, Sharon J.; Pearson, Talima; Keim, Paul

2010-01-01

Little is currently known about bacterial pathogen evolution and adaptation within the host during acute infection. Previous studies of Burkholderia pseudomallei, the etiologic agent of melioidosis, have shown that this opportunistic pathogen mutates rapidly both in vitro and in vivo at tandemly repeated loci, making this organism a relevant model for studying short-term evolution. In the current study, B. pseudomallei isolates cultured from multiple body sites from four Thai patients with disseminated melioidosis were subjected to fine-scale genotyping using multilocus variable-number tandem repeat analysis (MLVA). In order to understand and model the in vivo variable-number tandem repeat (VNTR) mutational process, we characterized the patterns and rates of mutations in vitro through parallel serial passage experiments of B. pseudomallei. Despite the short period of infection, substantial divergence from the putative founder genotype was observed in all four melioidosis cases. This study presents a paradigm for examining bacterial evolution over the short timescale of an acute infection. Further studies are required to determine whether the mutational process leads to phenotypic alterations that impact upon bacterial fitness in vivo. Our findings have important implications for future sampling strategies, since colonies in a single clinical sample may be genetically heterogeneous, and organisms in a culture taken late in the infective process may have undergone considerable genetic change compared with the founder inoculum. PMID:20090837

MR-Tandem: parallel X!Tandem using Hadoop MapReduce on Amazon Web Services.

PubMed

Pratt, Brian; Howbert, J Jeffry; Tasman, Natalie I; Nilsson, Erik J

2012-01-01

MR-Tandem adapts the popular X!Tandem peptide search engine to work with Hadoop MapReduce for reliable parallel execution of large searches. MR-Tandem runs on any Hadoop cluster but offers special support for Amazon Web Services for creating inexpensive on-demand Hadoop clusters, enabling search volumes that might not otherwise be feasible with the compute resources a researcher has at hand. MR-Tandem is designed to drop in wherever X!Tandem is already in use and requires no modification to existing X!Tandem parameter files, and only minimal modification to X!Tandem-based workflows. MR-Tandem is implemented as a lightly modified X!Tandem C++ executable and a Python script that drives Hadoop clusters including Amazon Web Services (AWS) Elastic Map Reduce (EMR), using the modified X!Tandem program as a Hadoop Streaming mapper and reducer. The modified X!Tandem C++ source code is Artistic licensed, supports pluggable scoring, and is available as part of the Sashimi project at http://sashimi.svn.sourceforge.net/viewvc/sashimi/trunk/trans_proteomic_pipeline/extern/xtandem/. The MR-Tandem Python script is Apache licensed and available as part of the Insilicos Cloud Army project at http://ica.svn.sourceforge.net/viewvc/ica/trunk/mr-tandem/. Full documentation and a windows installer that configures MR-Tandem, Python and all necessary packages are available at this same URL. brian.pratt@insilicos.com

ScanRanker: Quality Assessment of Tandem Mass Spectra via Sequence Tagging

PubMed Central

Ma, Ze-Qiang; Chambers, Matthew C.; Ham, Amy-Joan L.; Cheek, Kristin L.; Whitwell, Corbin W.; Aerni, Hans-Rudolf; Schilling, Birgit; Miller, Aaron W.; Caprioli, Richard M.; Tabb, David L.

2011-01-01

In shotgun proteomics, protein identification by tandem mass spectrometry relies on bioinformatics tools. Despite recent improvements in identification algorithms, a significant number of high quality spectra remain unidentified for various reasons. Here we present ScanRanker, an open-source tool that evaluates the quality of tandem mass spectra via sequence tagging with reliable performance in data from different instruments. The superior performance of ScanRanker enables it not only to find unassigned high quality spectra that evade identification through database search, but also to select spectra for de novo sequencing and cross-linking analysis. In addition, we demonstrate that the distribution of ScanRanker scores predicts the richness of identifiable spectra among multiple LC-MS/MS runs in an experiment, and ScanRanker scores assist the process of peptide assignment validation to increase confident spectrum identifications. The source code and executable versions of ScanRanker are available from http://fenchurch.mc.vanderbilt.edu. PMID:21520941

Tandem Nitrogen Functionalization of Porous Carbon: Toward Immobilizing Highly Active Palladium Nanoclusters for Dehydrogenation of Formic Acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhangpeng; Yang, Xinchun; Tsumori, Nobuko

2017-03-10

Highly dispersed palladium nanoclusters (Pd NCs) immobilized by a nitrogen (N)-functionalized porous carbon support (N-MSC-30) are synthesized by a wet chemical reduction method, wherein the N-MSC-30 prepared by a tandem low temperature heat-treatment approach proved to be a distinct support for stabilizing the Pd NCs. The prepared Pd/N-MSC-30 shows extremely high catalytic activity and recyclability for the dehydrogenation of formic acid (FA), affording the highest turnover frequency (TOF = 8414 h -1) at 333 K, which is much higher than that of the Pd catalyst supported on the N-MSC-30 prepared via a one-step process. This tandem heat treatment strategy providesmore » a facile and effective synthetic methodology to immobilize ultrafine metal NPs on N-functionalized carbon materials, which have tremendous application prospects in various catalytic fields.« less

Quantitation of tacrolimus in whole blood using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS).

PubMed

Donaldson, Keri J; Shaw, Leslie M

2010-01-01

We describe a multiple reaction monitoring positive ion HPLC/tandem mass spectrometric method for quantification of tacrolimus in human whole blood with online extraction and cleanup. Included in this procedure: API 2000 triple quadrupole mass spectrometer with turbo-ion spray source (Applied Biosystems, Foster City, CA); 10-port diverter/switching valve (Valco, Houston, TX); HPLC system (Agilent Technologies series 1100, Wilmington, DE); 10 mm (C(18)) guard cartridge (Perkin Elmer, Norwalk, CT) used as an extraction column; a Nova-Pak C18 analytical column (2.1 x 150 mm I.D., 4 microm, Waters Corp, Milford, MA); washing solution, methanol: 30 mM ammonium acetate pH 5.1 (80:20); eluting solution, methanol:30 mM ammonium acetate pH 5.1 (97:3); flow rate 0.8 mL/min; and a run-time of 2.8 min. The first and third quadrupoles were set to detect the ammonium adduct ion and a high mass fragment of tacrolimus (m/z 821.5-->768.3), and of an internal standard (ascomycin) (m/z 901.8-->834.4). The lower limit of quantification of this method is 3.75 mg/L. The concentration of drug is determined by comparing peak-area ratios for tacrolimus and internal standard to a standard curve constructed using non-weighted linear through zero regression.

Adsorption of Antibiotics on Graphene and Biochar in Aqueous Solutions Induced by π-π Interactions

PubMed Central

Peng, Bingquan; Chen, Liang; Que, Chenjing; Yang, Ke; Deng, Fei; Deng, Xiaoyong; Shi, Guosheng; Xu, Gang; Wu, Minghong

2016-01-01

The use of carbon based materials on the removal of antibiotics with high concentrations has been well studied, however the effect of this removal method is not clear on the actual concentration of environments, such as the hospital wastewater, sewage treatment plants and aquaculture wastewater. In this study, experimental studies on the adsorption of 7 antibiotics in environmental concentration of aqueous solutions by carbon based materials have been observed. Three kinds of carbon materials have shown very fast adsorption to antibiotics by liquid chromatography–tandem mass spectrometry (LC-MS-MS) detection, and the highest removal efficiency of antibiotics could reach to 100% within the range of detection limit. Surprisedly, the adsorption rate of graphene with small specific surface area was stronger than other two biochar, and adsorption rate of the two biochar which have approximate specific surface and different carbonization degree, was significantly different. The key point to the present observation were the π-π interactions between aromatic rings on adsorbed substance and carbon based materials by confocal laser scanning microscope observation. Moreover, adsorption energy markedly increased with increasing number of the π rings by using the density functional theory (DFT), showing the particular importance of π-π interactions in the adsorption process. PMID:27534975

Sheath liquid interface for the coupling of normal-phase liquid chromatography with electrospray mass spectrometry and its application to the analysis of neoflavonoids.

PubMed

Charles, Laurence; Laure, Frédéric; Raharivelomanana, Phila; Bianchini, Jean-Pierre

2005-01-01

A novel interface that allows normal-phase liquid chromatography to be coupled with electrospray ionization (ESI) is reported. A make-up solution of 60 mM ammonium acetate in methanol, infused at a 5 microl min(-1) flow-rate at the tip of the electrospray probe, provides a sheath liquid which is poorly miscible with the chromatographic effluent, but promotes efficient ionization of the targeted analytes. Protonated molecules generated in the ESI source were subjected to tandem mass spectrometric experiments in a triple-quadrupole mass spectrometer. The main fragmentation reactions were characterized for each analyte and specific mass spectral transitions were used to acquire chromatographic data in the multiple reaction monitoring detection mode. Results obtained during optimization of the sheath liquid composition and flow-rate suggest that the electrospray process was mainly under the control of the make-up solution, and that it forms an external charged layer around a neutral chromatographic mobile phase core. This sheath liquid interface was implemented for the analysis of some neoflavonoid compounds and its performance was evaluated. Limits of detection were established for calophillolide, inophyllum B, inophyllum P and inophyllum C at 100, 25, 15 and 100 ng ml(-1), respectively.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent.

PubMed

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A; Dietrich, Daniel R

2017-04-06

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%-40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues.

Adsorption of Antibiotics on Graphene and Biochar in Aqueous Solutions Induced by π-π Interactions

NASA Astrophysics Data System (ADS)

Peng, Bingquan; Chen, Liang; Que, Chenjing; Yang, Ke; Deng, Fei; Deng, Xiaoyong; Shi, Guosheng; Xu, Gang; Wu, Minghong

2016-08-01

The use of carbon based materials on the removal of antibiotics with high concentrations has been well studied, however the effect of this removal method is not clear on the actual concentration of environments, such as the hospital wastewater, sewage treatment plants and aquaculture wastewater. In this study, experimental studies on the adsorption of 7 antibiotics in environmental concentration of aqueous solutions by carbon based materials have been observed. Three kinds of carbon materials have shown very fast adsorption to antibiotics by liquid chromatography-tandem mass spectrometry (LC-MS-MS) detection, and the highest removal efficiency of antibiotics could reach to 100% within the range of detection limit. Surprisedly, the adsorption rate of graphene with small specific surface area was stronger than other two biochar, and adsorption rate of the two biochar which have approximate specific surface and different carbonization degree, was significantly different. The key point to the present observation were the π-π interactions between aromatic rings on adsorbed substance and carbon based materials by confocal laser scanning microscope observation. Moreover, adsorption energy markedly increased with increasing number of the π rings by using the density functional theory (DFT), showing the particular importance of π-π interactions in the adsorption process.

Tandem 1,5-hydride shift/1,5-S,N-cyclization with ethylene extrusion of 1,3-oxathiolane-substituted ketenimines and carbodiimides. An experimental and computational study.

PubMed

Alajarin, Mateo; Bonillo, Baltasar; Sanchez-Andrada, Pilar; Vidal, Angel

2010-06-04

Under thermal activation in solution, N-[2-(1,3-oxathiolan-2-yl)]phenyl ketenimines and carbodiimides were converted into 2,1-benzisothiazol-3-ones bearing a pendant N-styryl or imidoyl fragment, respectively. These processes should occur with the concomitant formation of ethylene as result of the fragmentation of the 1,3-oxathiolane ring. The conversions of ketenimines took place under softer thermal conditions, toluene 110 degrees C, than those of carbodiimides, o-xylene 160 degrees C. A computational DFT study unveiled the mechanistic course of these transformations, rare tandem processes consisting of an initial 1,5-hydride shift of the acetalic hydrogen atom to the central carbon atom of the heterocumulene function leading to the respective o-azaxylylene. This transient intermediate then converts, in a single step, into ethylene and the experimentally isolated benzisothiazolone. This latter stage of the mechanism is rather peculiar, combining a 1,5-cyclization by S-N bond formation, aromaticity recovery at the benzene nucleus, and the fragmentation of the oxathiolane framework originating a new carbonyl group. It can be related with a vinylogous retro-ene reaction and shows pseudopericyclic characteristics. The computations also revealed that the alternative 6pi electrocyclization of the transient o-azaxylylenes cannot compete, on kinetic and thermodynamic grounds, with the experimentally observed reaction channel. The two alternative reaction paths of a number of ketenimines and carbodiimides were computationally scrutinized, the results being in accord with the experimental outcomes. In addition, sulfur extrusion from the benzisothiazolones by the action of triphenylphosphine under two different reaction conditions led to three different types of heterocyclic products, 4(3H)-quinolones, quinolino[2,1-b]quinazolin-5,12-diones, and dibenzo[b,f][1,5]diazocin-6,12-diones, whose formation is explained by the initial formation of an intermediate imidoylketene. This reactive species could be trapped by a nucleophilic solvent, ethanol.

Ultra high performance liquid chromatography with tandem mass spectrometry screening and mutagenicity evaluation of photodegradation products of Carmoisine (E122) dye in a beverage.

PubMed

Yamjala, Karthik; Nainar, Meyyanathan Subramania; Ramisetti, Nageswara Rao

2016-06-01

The present study deals with the separation and identification of the photodegradation products formed when a commercial soft drink containing Carmoisine (E122) dye was exposed to natural sunlight. An ultra high performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry method was developed and validated to identify the unknown species of E122. During the study, it was observed that the dye decolourizes rapidly in beverage when compared to model standard solutions. The sunlight irradiation of beverage containing E122 resulted in four photodegradation products as identified by nontarget screening using high-resolution tandem mass spectrometry. Accurate mass measurements were used to identify the elemental composition, and to elucidate the structures of degradation products a software tool was employed. The degradation products (P1-P4) were formed from the interactions of the dye with other ingredients present in the beverage. The toxicity of the degradation products was evaluated on five bacterial strains (TA98, TA100, TA1535, TA1537, and WP2 uvrA pKM101) through an in vitro bacterial reverse mutation assay. The photodegradation products showed strong mutagenic potential in strain TA 100 (without S9) as detected by the Ames assay. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of peptide adsorption-controlled liquid chromatography-tandem mass spectrometric (PAC-LC-MS/MS) method for simple and simultaneous quantitation of amyloid β 1-38, 1-40, 1-42 and 1-43 peptides in dog cerebrospinal fluid.

PubMed

Goda, Ryoya; Kobayashi, Nobuhiro

2012-05-01

To evaluate the usefulness of the peptide adsorption-controlled liquid chromatography-tandem mass spectrometry (PAC-LC-MS/MS) for reproducible measurement of peptides in biological fluids, simultaneous quantitation of amyloid β 1-38, 1-40, 1-42 and 1-43 peptides (Aβ38, Aβ40, Aβ42 and Aβ43) in dog cerebrospinal fluid (CSF) was tried. Each stable isotope labeled Aβ was used as the internal standard to minimize the influence of CSF matrix on the reproducible Aβ quantitation. To reduce a loss of Aβ during the pretreatment procedures, the dog CSF diluted by water-acetic acid-methanol (2:6:1, v/v/v) was loaded on PAC-LC-MS/MS directly. Quantification of the Aβ in the diluted dog CSF was carried out using multiple reaction monitoring (MRM) mode. The [M+5H(5+)] and b(5+) ion fragment of each peptide were chosen as the precursor and product ions for MRM transitions of each peptide. The calibration curves were drawn from Aβ standard calibration solutions using PAC-LC-MS/MS. Analysis of dog CSF samples suggests that the basal concentration of Aβ38, Aβ40, Aβ42 and Aβ43 in dog CSF is approximately 300, 900, 200 and 30 pM, respectively. This is the first time Aβ concentrations in dog CSF have been reported. Additionally, the evaluation of intra- and inter-day reproducibility of analysis of Aβ standard solution, the freeze-thaw stability and the room temperature stability of Aβ standard solution suggest that the PAC-LC-MS/MS method enables reproducible Aβ quantitation. Copyright © 2012 Elsevier B.V. All rights reserved.

Quantification of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using a simplified extraction method coupled with liquid chromatography-triple quadrupole tandem mass spectrometry.

PubMed

Cho, Sang-Hyun; Park, Jin-A; Zheng, Weijia; Abd El-Aty, A M; Kim, Seong-Kwan; Choi, Jeong-Min; Yi, Hee; Cho, Soo-Min; Afifi, Nehal A; Shim, Jae-Han; Chang, Byung-Joon; Kim, Jin-Suk; Shin, Ho-Chul

2017-10-15

In this study, a simple analytical approach has been developed and validated for the determination of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A 0.1% solution of acetic acid in acetonitrile combined with n-hexane was used for deproteinization and defatting of all tested matrices and the target drugs were well separated on a Waters Xbridge™ C18 analytical column using a mobile phase consisting of 0.1% acetic acid (A) and 0.1% solution of acetic acid in methanol (B). The linearity estimated from six-point matrix-matched calibrations was good, with coefficients of determination ≥0.9873. The limits of quantification (LOQs) for bupivacaine hydrochloride and isoflupredone acetate were 1 and 2ngg -1 , respectively. Recovery percentages in the ranges of 72.51-112.39% (bupivacaine hydrochloride) and 72.58-114.56% (isoflupredone acetate) were obtained from three different fortification concentrations with relative standard deviations (RSDs) of <15.14%. All samples for the experimental work and method application were collected from the local markets in Seoul, Republic of Korea, and none of them tested positive for the target drugs. In conclusion, a simple method using a 0.1% solution of acetic acid in acetonitrile and n-hexane followed by LC-MS/MS could effectively extract bupivacaine hydrochloride and isoflupredone acetate from porcine muscle, beef, milk, egg, shrimp, flatfish, and eel samples. Copyright © 2017 Elsevier B.V. All rights reserved.

MR-Tandem: parallel X!Tandem using Hadoop MapReduce on Amazon Web Services

PubMed Central

Pratt, Brian; Howbert, J. Jeffry; Tasman, Natalie I.; Nilsson, Erik J.

2012-01-01

Summary: MR-Tandem adapts the popular X!Tandem peptide search engine to work with Hadoop MapReduce for reliable parallel execution of large searches. MR-Tandem runs on any Hadoop cluster but offers special support for Amazon Web Services for creating inexpensive on-demand Hadoop clusters, enabling search volumes that might not otherwise be feasible with the compute resources a researcher has at hand. MR-Tandem is designed to drop in wherever X!Tandem is already in use and requires no modification to existing X!Tandem parameter files, and only minimal modification to X!Tandem-based workflows. Availability and implementation: MR-Tandem is implemented as a lightly modified X!Tandem C++ executable and a Python script that drives Hadoop clusters including Amazon Web Services (AWS) Elastic Map Reduce (EMR), using the modified X!Tandem program as a Hadoop Streaming mapper and reducer. The modified X!Tandem C++ source code is Artistic licensed, supports pluggable scoring, and is available as part of the Sashimi project at http://sashimi.svn.sourceforge.net/viewvc/sashimi/trunk/trans_proteomic_pipeline/extern/xtandem/. The MR-Tandem Python script is Apache licensed and available as part of the Insilicos Cloud Army project at http://ica.svn.sourceforge.net/viewvc/ica/trunk/mr-tandem/. Full documentation and a windows installer that configures MR-Tandem, Python and all necessary packages are available at this same URL. Contact: brian.pratt@insilicos.com PMID:22072385

Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of Ascaris reveals a novel fold and two discrete lipid-binding sites.

PubMed

Meenan, Nicola A G; Ball, Graeme; Bromek, Krystyna; Uhrín, Dušan; Cooper, Alan; Kennedy, Malcolm W; Smith, Brian O

2011-04-19

Nematode polyprotein allergens (NPAs) are an unusual class of lipid-binding proteins found only in nematodes. They are synthesized as large, tandemly repetitive polyproteins that are post-translationally cleaved into multiple copies of small lipid binding proteins with virtually identical fatty acid and retinol (Vitamin A)-binding characteristics. They are probably central to transport and distribution of small hydrophobic compounds between the tissues of nematodes, and may play key roles in nutrient scavenging, immunomodulation, and IgE antibody-based responses in infection. In some species the repeating units are diverse in amino acid sequence, but, in ascarid and filarial nematodes, many of the units are identical or near-identical. ABA-1A is the most common repeating unit of the NPA of Ascaris suum, and is closely similar to that of Ascaris lumbricoides, the large intestinal roundworm of humans. Immune responses to NPAs have been associated with naturally-acquired resistance to infection in humans, and the immune repertoire to them is under strict genetic control. The solution structure of ABA-1A was determined by protein nuclear magnetic resonance spectroscopy. The protein adopts a novel seven-helical fold comprising a long central helix that participates in two hollow four-helical bundles on either side. Discrete hydrophobic ligand-binding pockets are found in the N-terminal and C-terminal bundles, and the amino acid sidechains affected by ligand (fatty acid) binding were identified. Recombinant ABA-1A contains tightly-bound ligand(s) of bacterial culture origin in one of its binding sites. This is the first mature, post-translationally processed, unit of a naturally-occurring tandemly-repetitive polyprotein to be structurally characterized from any source, and it belongs to a new structural class. NPAs have no counterparts in vertebrates, so represent potential targets for drug or immunological intervention. The nature of the (as yet) unidentified bacterial ligand(s) may be pertinent to this, as will our characterization of the unusual binding sites.

Enhancing Accuracy in Molecular Weight Determination of Highly Heterogeneously Glycosylated Proteins by Native Tandem Mass Spectrometry.

PubMed

Wang, Guanbo; de Jong, Rob N; van den Bremer, Ewald T J; Parren, Paul W H I; Heck, Albert J R

2017-05-02

The determination of molecular weights (MWs) of heavily glycosylated proteins is seriously hampered by the physicochemical characteristics and heterogeneity of the attached carbohydrates. Glycosylation impacts protein migration during sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and size-exclusion chromatography (SEC) analysis. Standard electrospray ionization (ESI)-mass spectrometry does not provide a direct solution as this approach is hindered by extensive interference of ion signals caused by closely spaced charge states of broadly distributed glycoforms. Here, we introduce a native tandem MS-based approach, enabling charge-state resolution and charge assignment of protein ions including those that escape mass analysis under standard MS conditions. Using this method, we determined the MW of two model glycoproteins, the extra-cellular domains of the highly and heterogeneously glycosylated proteins CD38 and epidermal growth factor receptor (EGFR), as well as the overall MW and binding stoichiometries of these proteins in complex with a specific antibody.

QuEChERS Purification Combined with Ultrahigh-Performance Liquid Chromatography Tandem Mass Spectrometry for Simultaneous Quantification of 25 Mycotoxins in Cereals.

PubMed

Sun, Juan; Li, Weixi; Zhang, Yan; Hu, Xuexu; Wu, Li; Wang, Bujun

2016-12-15

A method based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) purification combined with ultrahigh performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), was optimized for the simultaneous quantification of 25 mycotoxins in cereals. Samples were extracted with a solution containing 80% acetonitrile and 0.1% formic acid, and purified with QuEChERS before being separated by a C18 column. The mass spectrometry was conducted by using positive electrospray ionization (ESI+) and multiple reaction monitoring (MRM) models. The method gave good linear relations with regression coefficients ranging from 0.9950 to 0.9999. The detection limits ranged from 0.03 to 15.0 µg·kg -1 , and the average recovery at three different concentrations ranged from 60.2% to 115.8%, with relative standard deviations (RSD%) varying from 0.7% to 19.6% for the 25 mycotoxins. The method is simple, rapid, accurate, and an improvement compared with the existing methods published so far.

Clonazepam quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry in a bioequivalence study.

PubMed

Cavedal, Luiz E; Mendes, Fabiana D; Domingues, Claudia C; Patni, Anil K; Monif, Tausif; Reyar, Simrit; Pereira, Alberto Dos S; Mendes, Gustavo D; De Nucci, Gilberto

2007-01-01

A rapid, sensitive and specific method for quantifying clonazepam in human plasma using diazepam as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using a hexane/diethylether (20 : 80, v/v) solution. The extracts were analysed by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed on a Jones Genesis C8 4 microm analytical column (100 x 2.1 mm i.d.). The method had a chromatographic run time of 3.0 min and a linear calibration curve over the range 0.5-50 ng/ml (r2 > 0.9965). The limit of quantification was 0.5 ng/ml. This HPLC/MS/MS procedure was used to assess the bioequivalence of two clonazepam 2 mg tablet formulations (clonazepam test formulation from Ranbaxy Laboratories Ltd and Rivotril from Roche Laboratórios Ltda as standard reference formulation). Copyright 2006 John Wiley & Sons, Ltd.

Determination of lansoprazole in human plasma by rapid resolution liquid chromatography-electrospray tandem mass spectrometry: application to a bioequivalence study on Chinese volunteers.

PubMed

Wu, Guo-Lan; Zhou, Hui-Li; Shentu, Jian-Zhong; He, Qiao-Jun; Yang, Bo

2008-12-15

A simple, sensitive and rapid LC/MS/MS method was developed for the quantification of lansoprazole in human plasma. After a simple sample preparation procedure by one-step protein precipitation with acetonitrile, lansoprazole and the internal standard bicalutamide were chromatographed on a Zorbax SB-C(18) (3.0 mm x 150 mm, 3.5 microm, Agilent) column with the mobile phase consisted of methanol-water (70:30, v/v, containing 5 mM ammonium formate, pH was adjusted to 7.85 by 1% ammonia solution). Detection was performed on a triple quadrupole tandem mass spectrometry by multiple reaction monitoring (MRM) mode via negative eletrospray ionization source (ESI(-)). The lower limit of quantification was 5.5 ng/mL, and the assay exhibited a linear range of 5.5-2200.0 ng/mL. The validated method was successfully applied to investigate the bioequivalence between two kinds of preparation (test vs. reference product) in twenty-eight healthy male Chinese volunteers.

Capillary zone electrophoresis-tandem mass spectrometry detects low concentration host cell impurities in monoclonal antibodies

PubMed Central

Zhu, Guijie; Sun, Liangliang; Heidbrink-Thompson, Jennifer; Kuntumalla, Srilatha; Lin, Hung-yu; Larkin, Christopher J.; McGivney, James B.; Dovichi, Norman J.

2016-01-01

We have evaluated capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry (CZE-ESI-MS/MS) for detection of trace amounts of host cell protein impurities in recombinant therapeutics. Compared to previously published procedures, we have optimized the buffer pH used in the formation of a pH junction to increase injection volume. We also prepared a five-point calibration curve by spiking twelve standard proteins into a solution of a human monoclonal antibody. A custom CZE-MS/MS system was used to analyze the tryptic digest of this mixture without depletion of the antibody. CZE generated a ~70 min separation window (~90 min total analysis duration) and ~300 peak capacity. We also analyzed the sample using ultra-performance liquid chromatography (UPLC)-MS/MS. CZE-MS/MS generated ~five times higher base peak intensity and more peptide identifications for low-level spiked proteins. Both methods detected all proteins spiked at the ~100 ppm level with respect to the antibody. PMID:26530276

CdCl2 passivation of polycrystalline CdMgTe and CdZnTe absorbers for tandem photovoltaic cells

NASA Astrophysics Data System (ADS)

Swanson, Drew E.; Reich, Carey; Abbas, Ali; Shimpi, Tushar; Liu, Hanxiao; Ponce, Fernando A.; Walls, John M.; Zhang, Yong-Hang; Metzger, Wyatt K.; Sampath, W. S.; Holman, Zachary C.

2018-05-01

As single-junction silicon solar cells approach their theoretical limits, tandems provide the primary path to higher efficiencies. CdTe alloys can be tuned with magnesium (CdMgTe) or zinc (CdZnTe) for ideal tandem pairing with silicon. A II-VI/Si tandem holds the greatest promise for inexpensive, high-efficiency top cells that can be quickly deployed in the market using existing polycrystalline CdTe manufacturing lines combined with mature silicon production lines. Currently, all high efficiency polycrystalline CdTe cells require a chloride-based passivation process to passivate grain boundaries and bulk defects. This research examines the rich chemistry and physics that has historically limited performance when extending Cl treatments to polycrystalline 1.7-eV CdMgTe and CdZnTe absorbers. A combination of transmittance, quantum efficiency, photoluminescence, transmission electron microscopy, and energy-dispersive X-ray spectroscopy clearly reveals that during passivation, Mg segregates and out-diffuses, initially at the grain boundaries but eventually throughout the bulk. CdZnTe exhibits similar Zn segregation behavior; however, the onset and progression is localized to the back of the device. After passivation, CdMgTe and CdZnTe can render a layer that is reduced to predominantly CdTe electro-optical behavior. Contact instabilities caused by inter-diffusion between the layers create additional complications. The results outline critical issues and paths for these materials to be successfully implemented in Si-based tandems and other applications.

Direct Maximization of Protein Identifications from Tandem Mass Spectra*

PubMed Central

Spivak, Marina; Weston, Jason; Tomazela, Daniela; MacCoss, Michael J.; Noble, William Stafford

2012-01-01

The goal of many shotgun proteomics experiments is to determine the protein complement of a complex biological mixture. For many mixtures, most methodological approaches fall significantly short of this goal. Existing solutions to this problem typically subdivide the task into two stages: first identifying a collection of peptides with a low false discovery rate and then inferring from the peptides a corresponding set of proteins. In contrast, we formulate the protein identification problem as a single optimization problem, which we solve using machine learning methods. This approach is motivated by the observation that the peptide and protein level tasks are cooperative, and the solution to each can be improved by using information about the solution to the other. The resulting algorithm directly controls the relevant error rate, can incorporate a wide variety of evidence and, for complex samples, provides 18–34% more protein identifications than the current state of the art approaches. PMID:22052992

Hybrid bio-photo-electro-chemical cells for solar water splitting

PubMed Central

Pinhassi, Roy I.; Kallmann, Dan; Saper, Gadiel; Dotan, Hen; Linkov, Artyom; Kay, Asaf; Liveanu, Varda; Schuster, Gadi; Adir, Noam; Rothschild, Avner

2016-01-01

Photoelectrochemical water splitting uses solar power to decompose water to hydrogen and oxygen. Here we show how the photocatalytic activity of thylakoid membranes leads to overall water splitting in a bio-photo-electro-chemical (BPEC) cell via a simple process. Thylakoids extracted from spinach are introduced into a BPEC cell containing buffer solution with ferricyanide. Upon solar-simulated illumination, water oxidation takes place and electrons are shuttled by the ferri/ferrocyanide redox couple from the thylakoids to a transparent electrode serving as the anode, yielding a photocurrent density of 0.5 mA cm−2. Hydrogen evolution occurs at the cathode at a bias as low as 0.8 V. A tandem cell comprising the BPEC cell and a Si photovoltaic module achieves overall water splitting with solar to hydrogen efficiency of 0.3%. These results demonstrate the promise of combining natural photosynthetic membranes and man-made photovoltaic cells in order to convert solar power into hydrogen fuel. PMID:27550091

Numerical Evaluation of the "Dual-Kernel Counter-flow" Matric Convolution Integral that Arises in Discrete/Continuous (D/C) Control Theory

NASA Technical Reports Server (NTRS)

Nixon, Douglas D.

2009-01-01

Discrete/Continuous (D/C) control theory is a new generalized theory of discrete-time control that expands the concept of conventional (exact) discrete-time control to create a framework for design and implementation of discretetime control systems that include a continuous-time command function generator so that actuator commands need not be constant between control decisions, but can be more generally defined and implemented as functions that vary with time across sample period. Because the plant/control system construct contains two linear subsystems arranged in tandem, a novel dual-kernel counter-flow convolution integral appears in the formulation. As part of the D/C system design and implementation process, numerical evaluation of that integral over the sample period is required. Three fundamentally different evaluation methods and associated algorithms are derived for the constant-coefficient case. Numerical results are matched against three available examples that have closed-form solutions.

Hybrid bio-photo-electro-chemical cells for solar water splitting.

PubMed

Pinhassi, Roy I; Kallmann, Dan; Saper, Gadiel; Dotan, Hen; Linkov, Artyom; Kay, Asaf; Liveanu, Varda; Schuster, Gadi; Adir, Noam; Rothschild, Avner

2016-08-23

Photoelectrochemical water splitting uses solar power to decompose water to hydrogen and oxygen. Here we show how the photocatalytic activity of thylakoid membranes leads to overall water splitting in a bio-photo-electro-chemical (BPEC) cell via a simple process. Thylakoids extracted from spinach are introduced into a BPEC cell containing buffer solution with ferricyanide. Upon solar-simulated illumination, water oxidation takes place and electrons are shuttled by the ferri/ferrocyanide redox couple from the thylakoids to a transparent electrode serving as the anode, yielding a photocurrent density of 0.5 mA cm(-2). Hydrogen evolution occurs at the cathode at a bias as low as 0.8 V. A tandem cell comprising the BPEC cell and a Si photovoltaic module achieves overall water splitting with solar to hydrogen efficiency of 0.3%. These results demonstrate the promise of combining natural photosynthetic membranes and man-made photovoltaic cells in order to convert solar power into hydrogen fuel.

BF3·Et2O-promoted cleavage of the Csp-Csp2 bond of 2-propynolphenols/anilines: route to C2-alkenylated benzoxazoles and benzimidazoles.

PubMed

Song, Xian-Rong; Qiu, Yi-Feng; Song, Bo; Hao, Xin-Hua; Han, Ya-Ping; Gao, Pin; Liu, Xue-Yuan; Liang, Yong-Min

2015-02-20

A novel BF3·Et2O-promoted tandem reaction of easily prepared 2-propynolphenols/anilines and trimethylsilyl azide is developed to give C2-alkenylated benzoxazoles and benzimidazoles in moderate to good yields. Most reactions could be accomplished in 30 min at room temperature. This tandem process involves a Csp-Csp2 bond cleavage and a C-N bond formation. Moreover, both tertiary and secondary propargylic alcohols with diverse functional groups were tolerated under the mild conditions.

Tandem catalytic allylic amination and [2,3]-Stevens rearrangement of tertiary amines.

PubMed

Soheili, Arash; Tambar, Uttam K

2011-08-24

We have developed a catalytic allylic amination involving tertiary aminoesters and allylcarbonates, which is the first example of the use of tertiary amines as intermolecular nucleophiles in metal-catalyzed allylic substitution chemistry. This process is employed in a tandem ammonium ylide generation/[2,3]-rearrangement reaction, which formally represents a palladium-catalyzed Stevens rearrangement. Low catalyst loadings and mild reaction conditions are compatible with an unprecedented substrate scope for the ammonium ylide functionality, and products are generated in high yields and diastereoselectivities. Mechanistic studies suggested the reversible formation of an ammonium intermediate.

Tandem SN2' nucleophilic substitution/oxidative radical cyclization of aryl substituted allylic alcohols with 1,3-dicarbonyl compounds.

PubMed

Zhang, Zhen; Li, Cheng; Wang, Shao-Hua; Zhang, Fu-Min; Han, Xue; Tu, Yong-Qiang; Zhang, Xiao-Ming

2017-04-11

A novel and efficient tandem S N 2' nucleophilic substitution/oxidative radical cyclization reaction of aryl substituted allylic alcohols with 1,3-dicarbonyl compounds has been developed by using Mn(OAc) 3 as an oxidant, which enables the expeditious synthesis of polysubstituted dihydrofuran (DHF) derivatives in moderate to high yields. The use of weakly acidic hexafluoroisopropanol (HFIP) as the solvent rather than AcOH has successfully improved the yields and expanded the substrate scope of this type of radical cyclization reactions. Mechanistic studies confirmed the cascade reaction process involving a final radical cyclization.

Review of Software Tools for Design and Analysis of Large scale MRM Proteomic Datasets

PubMed Central

Colangelo, Christopher M.; Chung, Lisa; Bruce, Can; Cheung, Kei-Hoi

2013-01-01

Selective or Multiple Reaction monitoring (SRM/MRM) is a liquid-chromatography (LC)/tandem-mass spectrometry (MS/MS) method that enables the quantitation of specific proteins in a sample by analyzing precursor ions and the fragment ions of their selected tryptic peptides. Instrumentation software has advanced to the point that thousands of transitions (pairs of primary and secondary m/z values) can be measured in a triple quadrupole instrument coupled to an LC, by a well-designed scheduling and selection of m/z windows. The design of a good MRM assay relies on the availability of peptide spectra from previous discovery-phase LC-MS/MS studies. The tedious aspect of manually developing and processing MRM assays involving thousands of transitions has spurred to development of software tools to automate this process. Software packages have been developed for project management, assay development, assay validation, data export, peak integration, quality assessment, and biostatistical analysis. No single tool provides a complete end-to-end solution, thus this article reviews the current state and discusses future directions of these software tools in order to enable researchers to combine these tools for a comprehensive targeted proteomics workflow. PMID:23702368

Database Search Engines: Paradigms, Challenges and Solutions.

PubMed

Verheggen, Kenneth; Martens, Lennart; Berven, Frode S; Barsnes, Harald; Vaudel, Marc

2016-01-01

The first step in identifying proteins from mass spectrometry based shotgun proteomics data is to infer peptides from tandem mass spectra, a task generally achieved using database search engines. In this chapter, the basic principles of database search engines are introduced with a focus on open source software, and the use of database search engines is demonstrated using the freely available SearchGUI interface. This chapter also discusses how to tackle general issues related to sequence database searching and shows how to minimize their impact.

One-Pot Isomerization–Cross Metathesis–Reduction (ICMR) Synthesis of Lipophilic Tetrapeptides

PubMed Central

2015-01-01

An efficient, versatile and rapid method toward homologue series of lipophilic tetrapeptide derivatives (herein, the opioid peptides H-TIPP-OH and H-DIPP-OH) is reported. High atom economy and a minimal number of synthetic steps resulted from a one-pot tandem isomerization-cross metathesis-reduction sequence (ICMR), applicable both in solution and solid phase methodology. The broadly applicable synthesis proceeds with short reaction times and simple work-up, as illustrated in this work for alkylated opioid tetrapeptides. PMID:24906051

Biphasic microreactor for efficient membrane protein pretreatment with a combination of formic acid assisted solubilization, on-column pH adjustment, reduction, alkylation, and tryptic digestion.

PubMed

Zhao, Qun; Liang, Yu; Yuan, Huiming; Sui, Zhigang; Wu, Qi; Liang, Zhen; Zhang, Lihua; Zhang, Yukui

2013-09-17

Combining good dissolving ability of formic acid (FA) for membrane proteins and excellent complementary retention behavior of proteins on strong cation exchange (SCX) and strong anion exchange (SAX) materials, a biphasic microreactor was established to pretreat membrane proteins at microgram and even nanogram levels. With membrane proteins solubilized by FA, all of the proteomics sample processing procedures, including protein preconcentration, pH adjustment, reduction, and alkylation, as well as tryptic digestion, were integrated into an "SCX-SAX" biphasic capillary column. To evaluate the performance of the developed microreactor, a mixture of bovine serum albumin, myoglobin, and cytochrome c was pretreated. Compared with the results obtained by the traditional in-solution process, the peptide recovery (93% vs 83%) and analysis throughput (3.5 vs 14 h) were obviously improved. The microreactor was further applied for the pretreatment of 14 μg of membrane proteins extracted from rat cerebellums, and 416 integral membrane proteins (IMPs) (43% of total protein groups) and 103 transmembrane peptides were identified by two-dimensional nanoliquid chromatography-electrospray ionization tandem mass spectrometry (2D nano-LC-ESI-MS/MS) in triplicate analysis. With the starting sample preparation amount decreased to as low as 50 ng, 64 IMPs and 17 transmembrane peptides were identified confidently, while those obtained by the traditional in-solution method were 10 and 1, respectively. All these results demonstrated that such an "SCX-SAX" based biphasic microreactor could offer a promising tool for the pretreatment of trace membrane proteins with high efficiency and throughput.

Automated array assembly, phase 2

NASA Technical Reports Server (NTRS)

Carbajal, B. G.

1979-01-01

Tasks of scaling up the tandem junction cell (TJC) from 2 cm x 2 cm to 6.2 cm and the assembly of several modules using these large area TJC's are described. The scale-up of the TJC was based on using the existing process and doing the necessary design activities to increase the cell area to an acceptably large area. The design was carried out using available device models. The design was verified and sample large area TJCs were fabricated. Mechanical and process problems occurred causing a schedule slippage that resulted in contract expiration before enough large-area TJCs were fabricated to populate the sample tandem junction modules (TJM). A TJM design was carried out in which the module interconnects served to augment the current collecting buses on the cell. No sample TJMs were assembled due to a shortage of large-area TJCs.

Quantification of short chain amines in aqueous matrices using liquid chromatography electrospray ionization tandem mass spectrometry.

PubMed

Viidanoja, Jyrki

2017-01-13

A new liquid chromatography-electrospray ionization-tandem Mass Spectrometry (LC-ESI-MS/MS) method was developed for the determination of more than 20 C 1 -C 6 alkyl and alkanolamines in aqueous matrices. The method employs Hydrophilic Interaction Liquid Chromatography Multiple Reaction Monitoring (HILIC-MRM) with a ZIC-pHILIC column and four stable isotope labeled amines as internal standards for signal normalization and quantification of the amines. The method was validated using a refinery process water sample that was obtained from a cooling cycle of crude oil distillation. The averaged within run precision, between run precision and accuracy were generally within 2-10%, 1-9% and 80-120%, respectively, depending on the analyte and concentration level. Selected aqueous process samples were analyzed with the method. Copyright © 2016 Elsevier B.V. All rights reserved.

Conversion of raw lignocellulosic biomass into branched long-chain alkanes through three tandem steps.

PubMed

Li, Chunrui; Ding, Daqian; Xia, Qineng; Liu, Xiaohui; Wang, Yanqin

2016-07-07

Synthesis of branched long-chain alkanes from renewable biomass has attracted intensive interest in recent years, but the feedstock for this synthesis is restricted to platform chemicals. Here, we develop an effective and energy-efficient process to convert raw lignocellulosic biomass (e.g., corncob) into branched diesel-range alkanes through three tandem steps for the first time. Furfural and isopropyl levulinate (LA ester) were prepared from hemicellulose and cellulose fractions of corncob in toluene/water biphasic system with added isopropanol, which was followed by double aldol condensation of furfural with LA ester into C15 oxygenates and the final hydrodeoxygenation of C15 oxygenates into branched long-chain alkanes. The core point of this tandem process is the addition of isopropanol in the first step, which enables the spontaneous transfer of levulinic acid (LA) into the toluene phase in the form of LA ester through esterification, resulting in LA ester co-existing with furfural in the same phase, which is the basis for double aldol condensation in the toluene phase. Moreover, the acidic aqueous phase and toluene can be reused and the residues, including lignin and humins in aqueous phase, can be separated and carbonized to porous carbon materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Tandem CARDs of NOD2: Intramolecular Interactions and Recognition of RIP2

PubMed Central

Fridh, Veronica; Rittinger, Katrin

2012-01-01

Caspase recruitment domains (CARDs) are homotypic protein interaction modules that link the stimulus-dependent assembly of large signaling platforms such as inflammasomes to the activation of downstream effectors that often include caspases and kinases and thereby play an important role in the regulation of inflammatory and apoptotic signaling pathways. NOD2 belongs to the NOD-like (NLR) family of intracellular pattern recognition receptors (PRR) and induces activation of the NF-κB pathway in response to the recognition of bacterial components. This process requires the specific recognition of the CARD of the protein kinase RIP2 by the tandem CARDs of NOD2. Here we demonstrate that the tandem CARDs of NOD2 are engaged in an intramolecular interaction that is important for the structural stability of this region. Using a combination of ITC and pull-down experiments we identify distinct surface areas that are involved in the intramolecular tandem CARD interaction and the interaction with the downstream effector RIP2. Our findings indicate that while CARDa of NOD2 might be the primary binding partner of RIP2 the two CARDs of NOD2 do not act independently of one another but may cooperate to from a binding surface that is distinct from that of single CARDs. PMID:22470564

Technology computer aided design of 29.5% efficient perovskite/interdigitated back contact silicon heterojunction mechanically stacked tandem solar cell for energy-efficient applications

NASA Astrophysics Data System (ADS)

Pandey, Rahul; Chaujar, Rishu

2017-04-01

A 29.5% efficient perovskite/SiC passivated interdigitated back contact silicon heterojunction (IBC-SiHJ) mechanically stacked tandem solar cell device has been designed and simulated. This is a substantial improvement of 40% and 15%, respectively, compared to the transparent perovskite solar cell (21.1%) and Si solar cell (25.6%) operated individually. The perovskite solar cell has been used as a top subcell, whereas 250- and 25-μm-thick IBC-SiHJ solar cells have been used as bottom subcells. The realistic technology computer aided design analysis has been performed to understand the physical processes in the device and to make reliable predictions of the behavior. The performance of the top subcell has been obtained for different acceptor densities and hole mobility in Spiro-MeOTAD along with the impact of counter electrode work function. To incorporate the effect of material quality, the influence of carrier lifetimes has also been studied for perovskite top and IBC-SiHJ bottom subcells. The optical and electrical behavior of the devices has been obtained for both standalone as well as tandem configuration. Results reported in this study reveal that the proposed four-terminal tandem device may open a new door for cost-effective and energy-efficient applications.

Development of Multiple-Locus Variable-Number Tandem-Repeat Analysis for Molecular Subtyping of Campylobacter jejuni by Using Capillary Electrophoresis

PubMed Central

Techaruvichit, Punnida; Vesaratchavest, Mongkol; Keeratipibul, Suwimon; Kuda, Takashi; Kimura, Bon

2015-01-01

Campylobacter jejuni is a common cause of the frequently reported food-borne diseases in developed and developing nations. This study describes the development of multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) using capillary electrophoresis as a novel typing method for microbial source tracking and epidemiological investigation of C. jejuni. Among 36 tandem repeat loci detected by the Tandem Repeat Finder program, 7 VNTR loci were selected and used for characterizing 60 isolates recovered from chicken meat samples from retail shops, samples from chicken meat processing factory, and stool samples. The discrimination ability of MLVA was compared with that of multilocus sequence typing (MLST). MLVA (diversity index of 0.97 with 31 MLVA types) provided slightly higher discrimination than MLST (diversity index of 0.95 with 25 MLST types). The overall concordance between MLVA and MLST was estimated at 63% by adjusted Rand coefficient. MLVA predicted MLST type better than MLST predicted MLVA type, as reflected by Wallace coefficient (Wallace coefficient for MLVA to MLST versus MLST to MLVA, 86% versus 51%). MLVA is a useful tool and can be used for effective monitoring of C. jejuni and investigation of epidemics caused by C. jejuni. PMID:26025899

Concerted growth and ordering of cobalt nanorod arrays as revealed by tandem in situ SAXS-XAS studies

DOE PAGES

Cormary, Benoit; Li, Tao; Liakakos, Nikos; ...

2016-06-14

The molecular and ensemble dynamics for the growth of hierarchical supercrystals of cobalt nanorods have been studied by in situ tandem X-ray Absorption Spectroscopy – Small Angle X-ray Scattering (XAS - SAXS). The super-crystals were obtained by reducing a Co(II) precursor under H 2 in the presence of a long chain amine and a long chain carboxylic acid. Complementary time-dependent ex situ TEM studies were also performed. The experimental data provide critical insights into the nanorod growth mechanism, and unequivocal evidence for a concerted growth-organization process. Nanorod formation involves cobalt nucleation, a fast atom by atom anisotropic growth and amore » slower oriented attach-ment process that continues well after cobalt reduction is complete. As a result, smectic-like ordering of the nanorods appears very early in the process, as soon as nanoparticle elongation appears, and nanorod growth takes place inside organized super-lattices, which can be regarded as mesocrystals.« less

A multiple-locus variable-number tandem repeat analysis (MLVA) of Listeria monocytogenes isolated from Norwegian salmon-processing factories and from listeriosis patients.

PubMed

Lunestad, B T; Truong, T T T; Lindstedt, B-A

2013-10-01

The objective of this study was to characterize Listeria monocytogenes isolated from farmed Atlantic salmon (Salmo salar) and the processing environment in three different Norwegian factories, and compare these to clinical isolates by multiple-locus variable-number tandem repeat analysis (MLVA). The 65 L. monocytogenes isolates obtained gave 15 distinct MLVA profiles. There was great heterogeneity in the distribution of MLVA profiles in factories and within each factory. Nine of the 15 MLVA profiles found in the fish-associated isolates were found to match human profiles. The MLVA profile 07-07-09-10-06 was the most common strain in Norwegian listeriosis patients. L. monocytogenes with this profile has previously been associated with at least two known listeriosis outbreaks in Norway, neither determined to be due to fish consumption. However, since this profile was also found in fish and in the processing environment, fish should be considered as a possible food vehicle during sporadic cases and outbreaks of listeriosis.

Real-time HD Exchange Kinetics of Proteins from Buffered Aqueous Solution with Electrothermal Supercharging and Top-Down Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Going, Catherine C.; Xia, Zijie; Williams, Evan R.

2016-06-01

Electrothermal supercharging (ETS) with electrospray ionization produces highly charged protein ions from buffered aqueous solutions in which proteins have native folded structures. ETS increases the charge of ribonuclease A by 34%, whereas only a 6% increase in charge occurs for a reduced-alkylated form of this protein, which is unfolded and its structure is ~66% random coil in this solution. These results indicate that protein denaturation that occurs in the ESI droplets is the primary mechanism for ETS. ETS does not affect the extent of solution-phase hydrogen-deuterium exchange (HDX) that occurs for four proteins that have significantly different structures in solution, consistent with a droplet lifetime that is considerably shorter than observable rates of HDX. Rate constants for HDX of ubiquitin are obtained with a spatial resolution of ~1.3 residues with ETS and electron transfer dissociation of the 10+ charge-state using a single capillary containing a few μL of protein solution in which HDX continuously occurs. HDX protection at individual residues with ETS HDX is similar to that with reagent supercharging HDX and with solution-phase NMR, indicating that the high spray potentials required to induce ETS do not lead to HD scrambling.

Identification and characterization of tandem repeats in exon III of dopamine receptor D4 (DRD4) genes from different mammalian species.

PubMed

Larsen, Svend Arild; Mogensen, Line; Dietz, Rune; Baagøe, Hans Jørgen; Andersen, Mogens; Werge, Thomas; Rasmussen, Henrik Berg

2005-12-01

In this study we have identified and characterized dopamine receptor D4 (DRD4) exon III tandem repeats in 33 public available nucleotide sequences from different mammalian species. We found that the tandem repeat in canids could be described in a novel and simple way, namely, as a structure composed of 15- and 12- bp modules. Tandem repeats composed of 18-bp modules were found in sequences from the horse, zebra, onager, and donkey, Asiatic bear, polar bear, common raccoon, dolphin, harbor porpoise, and domestic cat. Several of these sequences have been analyzed previously without a tandem repeat being found. In the domestic cow and gray seal we identified tandem repeats composed of 36-bp modules, each consisting of two closely related 18-bp basic units. A tandem repeat consisting of 9-bp modules was identified in sequences from mink and ferret. In the European otter we detected an 18-bp tandem repeat, while a tandem repeat consisting of 27-bp modules was identified in a sequence from European badger. Both these tandem repeats were composed of 9-bp basic units, which were closely related with the 9-bp repeat modules identified in the mink and ferret. Tandem repeats could not be identified in sequences from rodents. All tandem repeats possessed a high GC content with a strong bias for C. On phylogenetic analysis of the tandem repeats evolutionary related species were clustered into the same groups. The degree of conservation of the tandem repeats varied significantly between species. The deduced amino acid sequences of most of the tandem repeats exhibited a high propensity for disorder. This was also the case with an amino acid sequence of the human DRD4 exon III tandem repeat, which was included in the study for comparative purposes. We identified proline-containing motifs for SH3 and WW domain binding proteins, potential phosphorylation sites, PDZ domain binding motifs, and FHA domain binding motifs in the amino acid sequences of the tandem repeats. The numbers of potential functional sites varied pronouncedly between species. Our observations provide a platform for future studies of the architecture and evolution of the DRD4 exon III tandem repeat, and they suggest that differences in the structure of this tandem repeat contribute to specialization and generation of diversity in receptor function.

Random and independent sampling of endogenous tryptic peptides from normal human EDTA plasma by liquid chromatography micro electrospray ionization and tandem mass spectrometry.

PubMed

Dufresne, Jaimie; Florentinus-Mefailoski, Angelique; Ajambo, Juliet; Ferwa, Ammara; Bowden, Peter; Marshall, John

2017-01-01

Normal human EDTA plasma samples were collected on ice, processed ice cold, and stored in a freezer at - 80 °C prior to experiments. Plasma test samples from the - 80 °C freezer were thawed on ice or intentionally warmed to room temperature. Protein content was measured by CBBR binding and the release of alcohol soluble amines by the Cd ninhydrin assay. Plasma peptides released over time were collected over C18 for random and independent sampling by liquid chromatography micro electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS) and correlated with X!TANDEM. Fully tryptic peptides by X!TANDEM returned a similar set of proteins, but was more computationally efficient, than "no enzyme" correlations. Plasma samples maintained on ice, or ice with a cocktail of protease inhibitors, showed lower background amounts of plasma peptides compared to samples incubated at room temperature. Regression analysis indicated that warming plasma to room temperature, versus ice cold, resulted in a ~ twofold increase in the frequency of peptide identification over hours-days of incubation at room temperature. The type I error rate of the protein identification from the X!TANDEM algorithm combined was estimated to be low compared to a null model of computer generated random MS/MS spectra. The peptides of human plasma were identified and quantified with low error rates by random and independent sampling that revealed 1000s of peptides from hundreds of human plasma proteins from endogenous tryptic peptides.

CdCl2 Passivation of Polycrystalline CdMgTe and CdZnTe Absorbers for Tandem Photovoltaic Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzger, Wyatt K; Swanson, Drew; Reich, Carey

As single-junction silicon solar cells approach their theoretical limits, tandems provide the primary path to higher efficiencies. CdTe alloys can be tuned with magnesium (CdMgTe) or zinc (CdZnTe) for ideal tandem pairing with silicon. A II-VI/Si tandem holds the greatest promise for inexpensive, high-efficiency top cells that can be quickly deployed in the market using existing polycrystalline CdTe manufacturing lines combined with mature silicon production lines. Currently, all high efficiency polycrystalline CdTe cells require a chloride-based passivation process to passivate grain boundaries and bulk defects. This research examines the rich chemistry and physics that has historically limited performance when extendingmore » Cl treatments to polycrystalline 1.7-eV CdMgTe and CdZnTe absorbers. A combination of transmittance, quantum efficiency, photoluminescence, transmission electron microscopy, and energy-dispersive X-ray spectroscopy clearly reveals that during passivation, Mg segregates and out-diffuses, initially at the grain boundaries but eventually throughout the bulk. CdZnTe exhibits similar Zn segregation behavior; however, the onset and progression is localized to the back of the device. After passivation, CdMgTe and CdZnTe can render a layer that is reduced to predominantly CdTe electro-optical behavior. Contact instabilities caused by inter-diffusion between the layers create additional complications. The results outline critical issues and paths for these materials to be successfully implemented in Si-based tandems and other applications.« less

Phytoremediation-biorefinery tandem for effective clean-up of metal contaminated soil and biomass valorisation.

PubMed

Sotenko, Maria; Coles, Stuart; Barker, Guy; Song, Lijiang; Jiang, Ying; Longhurst, Philip; Romanova, Tamara; Shuvaeva, Olga; Kirwan, Kerry

2017-11-02

During the last few decades, phytoremediation process has attracted much attention because of the growing concerns about the deteriorating quality of soil caused by anthropogenic activities. Here, a tandem phytoremediation/biorefinery process was proposed as a way to turn phytoremediation into a viable commercial method by producing valuable chemicals in addition to cleaned soil. Two agricultural plants (Sinapis alba and Helianthus annuus) were grown in moderately contaminated soil with ca. 100 ppm of Ni and further degraded by a fungal lignin degrader-Phanerochaete chrysosporium. Several parameters have been studied, including the viability of plants, biomass yield, and their accumulating and remediating potentials. Further, downstream processing showed that up to 80% of Ni can be easily extracted from contaminated biomass by aqueous extraction at mild conditions. Finally, it was demonstrated that the growth of plants on the contaminated soil could be degraded by P. chrysosporium, and the effect of nickel and biomass pretreatment on the solid-state fermentation was studied. The proposed and studied methodology in this work could pave the way for successful commercialization of the phytoremediation process in the near future.

Development of a high performance (188)W/(188)Re generator by using a synthetic alumina.

PubMed

Lee, Jun Sig; Lee, Jong-Soup; Park, Ul-Jae; Son, Kwang-Jae; Han, Hyon-Soo

2009-01-01

A synthetic alumina functionalized with a sulfate moiety has been developed as the column material of (99)Mo/(99m)Tc and (188)W/(188)Re generators. This material is synthesized by a sol-gel processing. In order to characterize the adsorbent for the (188)W/(188)Re separation, both batch and column contact experiments were conducted. As a result of the experiments, it is found that the maximum capacity of the adsorbent for tungsten is higher than 450mg/g. Hence it is possible to produce approximately 3Ci (188)W/(188)Re generator with only 1g of the adsorbent from (188)W solutions supplied from ORNL, USA or RIAR, Russia. A demonstration study was conducted to show the performance of an (188)W/(188)Re generator column. In this study, 1Ci of (188)W purchased from RIAR, Russia, is loaded on a 0.9cm ID column packed with 0.7g of the adsorbent. Elution of (188)Re is performed every 4-7 days by using the saline solution for more than three months. Nearly 100% of tungsten is loaded by passing 5ml of the (188)W solution (pH=8) through the dry packed column at a 1ml/min flow rate. Elution efficiency of (188)Re is 70-90% by using 5ml of the saline solution. The ratio of (188)W/(188)Re in the eluted solution is 0.002-0.003%. When a Sep-Pak containing 0.26g of acid alumina is installed as a tandem column, the ratio is decreased to less than 10(-3)%. Thin layer chromatography for the eluted (188)Re solution shows 100% radiochemical purity. Also, alumina content in the eluted solution shows less than 10ppm. Through this study, the performance of this adsorbent was successfully demonstrated. By using the developed adsorbent, minimization of the generator column and consequently the volume of eluant could be possible while maintaining the quality of (188)Re just as much as that available in the market.

GlycoDeNovo - an Efficient Algorithm for Accurate de novo Glycan Topology Reconstruction from Tandem Mass Spectra

NASA Astrophysics Data System (ADS)

Hong, Pengyu; Sun, Hui; Sha, Long; Pu, Yi; Khatri, Kshitij; Yu, Xiang; Tang, Yang; Lin, Cheng

2017-08-01

A major challenge in glycomics is the characterization of complex glycan structures that are essential for understanding their diverse roles in many biological processes. We present a novel efficient computational approach, named GlycoDeNovo, for accurate elucidation of the glycan topologies from their tandem mass spectra. Given a spectrum, GlycoDeNovo first builds an interpretation-graph specifying how to interpret each peak using preceding interpreted peaks. It then reconstructs the topologies of peaks that contribute to interpreting the precursor ion. We theoretically prove that GlycoDeNovo is highly efficient. A major innovative feature added to GlycoDeNovo is a data-driven IonClassifier which can be used to effectively rank candidate topologies. IonClassifier is automatically learned from experimental spectra of known glycans to distinguish B- and C-type ions from all other ion types. Our results showed that GlycoDeNovo is robust and accurate for topology reconstruction of glycans from their tandem mass spectra. [Figure not available: see fulltext.

Determination of melamine in animal feed based on liquid chromatography tandem mass spectrometry analysis and dynamic microwave-assisted extraction coupled on-line with strong cation-exchange resin clean-up.

PubMed

Chen, Ligang; Zeng, Qinglei; Du, Xiaobo; Sun, Xin; Zhang, Xiaopan; Xu, Yang; Yu, Aimin; Zhang, Hanqi; Ding, Lan

2009-11-01

In this work, a new method was developed for the determination of melamine (MEL) in animal feed. The method was based on the on-line coupling of dynamic microwave-assisted extraction (DMAE) to strong cation-exchange (SCX) resin clean-up. The MEL was first extracted by 90% acidified methanol aqueous solution (v/v, pH = 3) under the action of microwave energy, and then the extract was cooled and passed through the SCX resin. Thus, the protonated MEL was retained on the resin through ion exchange interaction and the sample matrixes were washed out. Some obvious benefits were achieved, such as acceleration of analytical process, together with reduction in manual handling, risk of contamination, loss of analyte, and sample consumption. Finally, the analyte was separated by a liquid chromatograph with a SCX analytical column, and then identified and quantitatived by a tandem mass spectrometry with positive ionization mode and multiple-reaction monitoring. The DMAE parameters were optimized by the Box-Behnken design. The linearity of quantification obtained by analyzing matrix-matched standards is in the range of 50-5,000 ng g(-1). The limit of detection and limit of quantification obtained are 12.3 and 41.0 ng g(-1), respectively. The mean intra- and inter-day precisions expressed as relative standard deviations with three fortified levels (50, 250, and 500 ng g(-1)) are 5.1% and 7.3%, respectively, and the recoveries of MEL are in the range of 76.1-93.5%. The proposed method was successfully applied to determine MEL in different animal feeds obtained from the local market. MEL was detectable with the contents of 279, 136, and 742 ng g(-1) in three samples.

Development and validation of a simple solid-phase extraction method coupled with liquid chromatography-triple quadrupole tandem mass spectrometry for simultaneous determination of lincomycin, tylosin A and tylosin B in royal jelly.

PubMed

Zheng, Weijia; Park, Jin-A; Abd El-Aty, A M; Kim, Seong-Kwan; Cho, Sang-Hyun; Choi, Jeong-Min; Warda, Mohamad; Wang, Jing; Shim, Jae-Han; Shin, Ho-Chul

2018-04-01

We have developed an analytical method for the determination of lincomycin, tylosin A and tylosin B residues in royal jelly using liquid chromatography-triple quadrupole tandem mass spectrometry analysis. For extraction and purification, we employed 1% trifluoroacetic acid and 0.1 m Na 2 EDTA solutions along with an Oasis HLB cartridge. The target antibiotics were well separated in a Kinetex EVO C 18 reversed-phase analytical column using a combination of 0.1% formate acid in ultrapure water (A) and acetonitrile (B) as the mobile phase. Good linearity was achieved over the tested concentration range (5-50 μg/kg) in matrix-matched standard calibration. The coefficients of determination (R 2 ) were 0.9933, 0.9933 and 0.996, for tylosin A, tylosin B and lincomycin, respectively. Fortified royal jelly spiked with three different concentrations of the tested antibiotics (5, 10 and 20 μg/kg) yielded recoveries in the range 80.94-109.26% with relative standard deviations ≤4%. The proposed method was applied to monitor 11 brand of royal jelly collected from domestic markets and an imported brand from New Zealand; all the samples tested negative for lincomycin, tylosin A and tylosin B residues. In conclusion, 1% trifluoroacetic acid and 0.1 m Na 2 EDTA aqueous solvents combined with solid-phase extraction could effectively complete the sample preparation process for royal jelly before analysis. The developed approach can be applied for a routine analysis of lincomycin, tylosin A and tylosin B residues in royal jelly. Copyright © 2017 John Wiley & Sons, Ltd.

Development and validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of acrivastine and pseudoephedrine in human plasma and its application in pharmacokinetics.

PubMed

He, J-C; Feng, E-F; Liu, M; Li, H-L; Tian, M; Zhang, Q; Dong, L-C; Xu, G-L

2012-10-01

A specific, sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the simultaneous determination of acrivastine and pseudoephedrine in human plasma samples. Plasma samples were processed and analyzed on a Phenomenex Luna 3 μ CN 100A column (150 mm×2.0 mm) eluted with the mobile phase consisting of methanol and 0.01 mol/L ammonium acetate water solution containing 0.1% formic acid (45:55, v/v) at a flow rate of 0.2 mL/min. The analytes were detected by positive ion electrospray ionization in multiple reaction monitoring mode. The transitions of m/z 349→278, m/z 166→148 and m/z 256→167 were monitored for acrivastine, pseudoephedrine and diphenhydramine (IS), respectively. The method was specific and sensitive with a lower limit of quantitation (LLOQ) of 1.52 ng/mL for acrivastine and 8.13 ng/mL for pseudoephedrine. The method showed good linearity in the range of 1.52~606.0 0 ng/mL for acrivastine and 8.13~813.12 ng/mL for pseudoephedrine (r≥0.996). The mean recovery were ranged 91.82% ~ 98.46% for acrivastine and 90.77% ~ 92.05% for pseudoephedrine. Validation results, such as accuracy, precision and repeatability were within the required limits. The method was successfully applied in a pharmacokinetic study of the acrivastine and pseudoephedrine hydrochloride compound capsule in humans. © Georg Thieme Verlag KG Stuttgart · New York.

Interactions of the Human LIP5 Regulatory Protein with Endosomal Sorting Complexes Required for Transport*♦

PubMed Central

Skalicky, Jack J.; Arii, Jun; Wenzel, Dawn M.; Stubblefield, William-May B.; Katsuyama, Angela; Uter, Nathan T.; Bajorek, Monika; Myszka, David G.; Sundquist, Wesley I.

2012-01-01

The endosomal sorting complex required for transport (ESCRT) pathway remodels membranes during multivesicular body biogenesis, the abscission stage of cytokinesis, and enveloped virus budding. The ESCRT-III and VPS4 ATPase complexes catalyze the membrane fission events associated with these processes, and the LIP5 protein helps regulate their interactions by binding directly to a subset of ESCRT-III proteins and to VPS4. We have investigated the biochemical and structural basis for different LIP5-ligand interactions and show that the first microtubule-interacting and trafficking (MIT) module of the tandem LIP5 MIT domain binds CHMP1B (and other ESCRT-III proteins) through canonical type 1 MIT-interacting motif (MIM1) interactions. In contrast, the second LIP5 MIT module binds with unusually high affinity to a novel MIM element within the ESCRT-III protein CHMP5. A solution structure of the relevant LIP5-CHMP5 complex reveals that CHMP5 helices 5 and 6 and adjacent linkers form an amphipathic “leucine collar” that wraps almost completely around the second LIP5 MIT module but makes only limited contacts with the first MIT module. LIP5 binds MIM1-containing ESCRT-III proteins and CHMP5 and VPS4 ligands independently in vitro, but these interactions are coupled within cells because formation of stable VPS4 complexes with both LIP5 and CHMP5 requires LIP5 to bind both a MIM1-containing ESCRT-III protein and CHMP5. Our studies thus reveal how the tandem MIT domain of LIP5 binds different types of ESCRT-III proteins, promoting assembly of active VPS4 enzymes on the polymeric ESCRT-III substrate. PMID:23105106

Gallium metal affinity capture tandem mass spectrometry for the selective detection of phosphopeptides in complex mixtures

PubMed Central

Blacken, Grady R.; Sadílek, Martin; Tureček, František

2008-01-01

Metal affinity capture tandem mass spectrometry (MAC-MSMS) is evaluated in a comparative study of a lysine-derived nitrilotriacetic acid (Nα, Nα-bis-(carboxymethyl)lysine, LysNTA) and an aspartic-acid-related iminodiacetic acid (N-(4-aminobutyl)aspartic acid, AspIDA) as selective phosphopeptide detection reagents. Both LysNTA and AspIDA spontaneously form ternary complexes with GaIII and phosphorylated amino acids and phosphopeptides upon mixing in solution. Collision-induced dissociation of positive complex ions produced by electrospray produces common fragments (LysNTA + H)+ or (AspIDA + H)+ at m/z 263 and 205, respectively. MSMS precursor scans using these fragments as reporter ions allow one to selectively detect multiple charge states of phosphopeptides in mixtures. It follows from this comparative study that LysNTA is superior to AspIDA in detecting phosphopeptides, possibly because of the higher coordination number and greater stability constant for GaIII – phosphopeptide complexation of the former reagent. In a continuing development of MAC-MSMS for proteomics applications, we demonstrate its utility in a post-column reaction format. Using a simple post-column-reaction ‘T’ and syringe pump to deliver our chelating reagents, α-casein tryptic phosphopeptides can be selectively analyzed from a solution containing a twofold molar excess of bovine serum albumin. The MAC-MSMS method is shown to be superior to the commonly used neutral loss scan for the common loss of phosphoric acid. PMID:18265438

Detailed phenolic composition of Vidal grape pomace by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

PubMed

Luo, Lanxin; Cui, Yan; Zhang, Shuting; Li, Lingxi; Suo, Hao; Sun, Baoshan

2017-11-15

Vidal Blanc grape (Vitis vinifera cv.) is the predominant white grape variety used for the production of icewine in China's Liaoning province. In this paper, the development and validation of the method by ultrahigh-performance liquid chromatography-tandem mass spectrometry has been performed for determination of the detailed phenolic composition in the skin, seed and stem of Vidal grapes. The validation of the method was realized by calculating the linearity, repeatability, precision, stability and the limits of detection (LOD) and quantification (LOQ) of standard solutions. All the curves exhibited good linearity (r 2 >0.9997) and the LOD and LOQ were in the range of 0.002-0.025 and 0.006-0.086μg/ml, respectively. Good repeatability (RSD<4.3%) and stability (RSD<3.7%) were also found. Results confirmed that the developed method was more effective and sensitive for simultaneous determination of the major phenolic compounds in Vidal grape pomace. The optimized and validated method of ultrahigh-performance liquid chromatography tandem two complementary techniques, fourier transform ion cyclotron resonance mass spectrometry and triple-quadrupole mass spectrometry, allowed to identify and quantify up to 35 phenolic compounds in Vidal grape pomace, which has, as far as we know, been reported this grapevine variety for the first time. Seeds, skins and stems exhibited different qualitative and quantitative phenolic profiles. These results provided useful information for recovery of phenolic antioxidants from different parts of icewine pomace. Copyright © 2017. Published by Elsevier B.V.

Determination of type A trichothecenes in coix seed by magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Dong, Maofeng; Si, Wenshuai; Wang, Weimin; Bai, Bing; Nie, Dongxia; Song, Weiguo; Zhao, Zhihui; Guo, Yirong; Han, Zheng

2016-09-01

Magnetic solid-phase extraction (m-SPE) is a promising sample preparation approach due to its convenience, speed, and simplicity. For the first time, a rapid and reliable m-SPE approach using magnetic multi-walled carbon nanotubes (m-MWCNTs) as the adsorbent was proposed for purification of type A trichothecenes including T-2 toxins (T2), HT-2 toxins (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO) in coix seed. The m-MWCNTs were synthesized by assembling the magnetic nanoparticles (Fe3O4) with MWCNTs by sonication through an aggregation wrap mechanism, and characterized by transmission electron microscope. Several key parameters affecting the performance of the procedure were extensively investigated including extraction solutions, desorption solvents, and m-MWCNT amounts. Under the optimal sample preparation conditions followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), high sensitivity (limit of quantification in the range of 0.3-1.5 μg kg(-1)), good linearity (R (2) > 0.99), satisfactory recovery (73.6-90.6 %), and acceptable precision (≤2.5 %) were obtained. The analytical performance of the developed method has also been successfully evaluated in real coix seed samples. Graphical Abstract Flow chart of determination of type A trichothecenes in coix seed by magnetic solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santoro, J; Witten, M; Haas, J

Purpose: Brachytherapy has been the standard of care for cervical cancer for 100 years. The treatment can be administered using an HDR (high dose rate) remote afterloader with a {sup 192}Ir source in an outpatient setting, a PDR afterloader with a {sup 192}Ir source, or with LDR manually loaded or a remote afterloader utilizing {sup 192}Ir or {sup 137}Cs sources in an inpatient setting. The procedure involves the placement of a tandem and ovoid, tandem and ring, or tandem and cylinder applicator in an operating room setting with the patient under general anesthesia. Inaccuracies introduced into the process occurring betweenmore » placement of the applicator and actual delivery can introduce uncertainty into the actual dose delivered to the tumor and critical organs. In this study we seek to investigate the dosimetric difference between an SBRT-based radiotherapy boost and conventional Brachytherapy in treating cervical cancer. Methods: Five HDR tandem and ovoid patients were planned using the Brachyvision treatment planning system and treated in four fractions using the Varian Varisource afterloader (Varian Medical Systems). For the same cohort, the patient planning CTs were imported into Multiplan (Accuray Inc) and a dose/fractionation-equivalent CyberKnife SBRT plan was retrospectively generated. Dosimetric quantities such as target/CTV D90, V90, D2cc for rectum, bladder, and bowel were measured and compared between the two modalities. Results: The CTV D90 for the tandem and ovoid was 2540cGy (90.7%) and 3009cGy (107.5%) for the CyberKnife plan. The D2cc for the rectum, bladder, and bowel were 1576cGy, 1641cGy, and 996cGy for the tandem and ovoid and 1374cGy, 1564cGy, and 1547cGy for CyberKnife. Conclusion: The D2cc doses to critical structures are comparable in both modalities. The CTV coverage is far superior for the CyberKnife plan. The dose distribution for CyberKnife has the advantage of increased conformality and lower maximum CTV dose.« less

Silver versus gold catalysis in tandem reactions of carbonyl functions onto alkynes: a versatile access to furoquinoline and pyranoquinoline cores.

PubMed

Godet, Thomas; Vaxelaire, Carine; Michel, Carine; Milet, Anne; Belmont, Philippe

2007-01-01

An efficient and versatile tandem process of acetalization and cycloisomerization reactions has been developed for the reactions of 1-alkynyl-2-carbonylquinoline substrates. The reaction occurs thanks to Au(I) and Ag(I) catalysis. Silver(I) catalysis has been extensively studied (11 different silver species) on a broad range of quinoline derivatives (variation of alkyne substituent, of carbonyl function and of nucleophiles), leading to a variety of furoquinoline and pyranoquinoline moieties. An insight is given for the presumed mechanism along with DFT-B3 LYP/6-31G** calculations to address the 6-endo and 5-exo regioselectivities observed.

Two tandem queues with general renewal input. 2: Asymptotic expansions for the diffusion model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knessl, C.; Tier, C.

1999-10-01

In Part 1 the authors formulated and solved a diffusion model for two tandem queues with exponential servers and general renewal arrivals. They thus obtained the easy traffic diffusion approximation to the steady state joint queue length distribution for this network. Here they study asymptotic and numerical properties of the diffusion approximation. In particular, analytical expressions are obtained for the tail probabilities. Both the joint distribution of the two queues and the marginal distribution of the second queue are considered. They also give numerical illustrations of how this marginal is affected by changes in the arrival and service processes.

Characterization of procyanidin B2 oxidation products in an apple juice model solution and confirmation of their presence in apple juice by high-performance liquid chromatography coupled to electrospray ion trap mass spectrometry.

PubMed

Poupard, Pascal; Sanoner, Philippe; Baron, Alain; Renard, Catherine M G C; Guyot, Sylvain

2011-11-01

Procyanidins (i.e. condensed tannins) are polyphenols commonly found in fruits. During juice and cider making, apple polyphenol oxidase catalyzes the oxidation of caffeoylquinic acid (CQA) into its corresponding o-quinone which further reacts with procyanidins and other polyphenols, leading to the formation of numerous oxidation products. However, the structure and the reaction pathways of these neoformed phenolic compounds are still largely unknown. Experiments were carried out on a model system to gain insights into the chemical processes occurring during the initial steps of fruit processing. Procyanidin B2 was oxidized by caffeoylquinic acid o-quinone (CQAoq) in an apple juice model solution. The reaction products were monitored using high performance liquid chromatography (HPLC) coupled to ultraviolet (UV)-visible and electrospray tandem mass spectrometry (ESI-MS/MS) in the negative mode. Oxidative conversion of procyanidin B2 ([M-H](-) at m/z 577) into procyanidin A2 at m/z 575 was unambiguously confirmed. In addition, several classes of products were characterized by their deprotonated molecules ([M-H](-)) and their MS/MS fragmentation patterns: hetero-dimers (m/z 929) and homo-dimers (m/z 1153 and 705) resulting from dimerization involving procyanidin and CQA molecules; intramolecular addition products at m/z 575, 573, 927, 1151 and 703. Interestingly, no extensive polymerization was observed. Analysis of a cider apple juice enabled comparison with the results obtained on a biosynthetic model solution. However, procyanidin A2 did not accumulate but seemed to be an intermediate in the formation of an end-product at m/z 573 for which two structural hypotheses are given. These structural modifications of native polyphenols as a consequence of oxidation probably have an impact on the organoleptic and nutritional properties of apple juices and other apple-derived foods. Copyright © 2011 John Wiley & Sons, Ltd.

Simultaneous quantification of GM1 and GM2 gangliosides by isotope dilution tandem mass spectrometry.

PubMed

Gu, Jianghong; Tifft, Cynthia J; Soldin, Steven J

2008-04-01

Gangliosides (GGs) are considered as diagnostic biomarkers and therapeutic targets and agents. The goal of this study was to develop a tandem mass spectrometry (MS/MS) method for the simultaneous measurement of both GM1 and GM2 gangliosides in human cerebrospinal fluid (CSF) samples in order to be able to determine their concentrations in patients with Tay-Sachs and Sandhoff disease and assess whether drugs or transplantation affect their concentrations. An API-4000 tandem mass spectrometer equipped with TurboIonSpray source and Shimadzu HPLC system was employed to perform the analysis using isotope dilution with deuterium labeled internal standards. To a 1.5 mL conical plastic Eppendorf centrifuge tube, 40 microL of human CSF sample was added and mixed with 400 microL of internal standard solution for deproteinization. After centrifugation, 100 microL of supernatant was injected onto a C-18 column. After a 2.5 min wash, the switching valve was activated and the analytes were eluted from the column with a water/methanol gradient into the MS/MS system. Quantification by multiple reaction-monitoring (MRM) analysis was performed in the negative mode. The within-day coefficients of variation were <3% for GM1 and <2% for GM2 and the between-day coefficients of variation were <5% for both GM1 and GM2 at all concentrations tested. Accuracy ranged between 98% and 102% for both analytes. Good linearity was also obtained within the concentration range of 10-200 ng/mL (6.5-129.3 nmol/L) for GM1 and 5-100 ng/mL (3.6-72.3 nmol/L) for GM2 (r> or =0.995). A new simple, accurate, and fast isotope dilution tandem mass spectrometry method was developed for the simultaneous quantification of GM1 and GM2 gangliosides in a small amount of human CSF. Concentrations were measured in "normal" CSF and in CSF from patients with Tay-Sachs disease.

Authentication of Closely Related Fish and Derived Fish Products Using Tandem Mass Spectrometry and Spectral Library Matching.

PubMed

Nessen, Merel A; van der Zwaan, Dennis J; Grevers, Sander; Dalebout, Hans; Staats, Martijn; Kok, Esther; Palmblad, Magnus

2016-05-11

Proteomics methodology has seen increased application in food authentication, including tandem mass spectrometry of targeted species-specific peptides in raw, processed, or mixed food products. We have previously described an alternative principle that uses untargeted data acquisition and spectral library matching, essentially spectral counting, to compare and identify samples without the need for genomic sequence information in food species populations. Here, we present an interlaboratory comparison demonstrating how a method based on this principle performs in a realistic context. We also increasingly challenge the method by using data from different types of mass spectrometers, by trying to distinguish closely related and commercially important flatfish, and by analyzing heavily contaminated samples. The method was found to be robust in different laboratories, and 94-97% of the analyzed samples were correctly identified, including all processed and contaminated samples.

An integrated experimental and theoretical reaction path search: analyses of the multistage reaction of an ionized diethylether dimer involving isomerization, proton transfer, and dissociation.

PubMed

Matsuda, Yoshiyuki; Xie, Min; Fujii, Asuka

2018-05-30

An ionization-induced multistage reaction of an ionized diethylether (DEE) dimer involving isomerization, proton transfer, and dissociation is investigated by combining infrared (IR) spectroscopy, tandem mass spectrometry, and a theoretical reaction path search. The vertically-ionized DEE dimer isomerizes to a hydrogen-bonded cluster of protonated DEE and the [DEE-H] radical through barrierless intermolecular proton transfer from the CH bond of the ionized moiety. This isomerization process is confirmed by IR spectroscopy and the theoretical reaction path search. The multiple dissociation pathways following the isomerization are analyzed by tandem mass spectrometry. The isomerized cluster dissociates stepwise into a [protonated DEE-acetaldehyde (AA)] cluster, protonated DEE, and protonated AA. The structure of the fragment ion is also analyzed by IR spectroscopy. The reaction map of the multistage processes is revealed through a harmony of these experimental and theoretical methods.

Batch and Flow Photochemical Benzannulations Based on the Reaction of Ynamides and Diazo Ketones. Application to the Synthesis of Polycyclic Aromatic and Heteroaromatic Compounds

PubMed Central

Willumstad, Thomas P.; Haze, Olesya; Mak, Xiao Yin; Lam, Tin Yiu; Wang, Yu-Pu; Danheiser*, Rick L.

2013-01-01

Highly substituted polycyclic aromatic and heteroaromatic compounds are produced via a two-stage tandem benzannulation/cyclization strategy. The initial benzannulation step proceeds via a pericyclic cascade mechanism triggered by thermal or photochemical Wolff rearrangement of a diazo ketone. The photochemical process can be performed using a continuous flow reactor which facilitates carrying out reactions on a large scale and minimizes the time required for photolysis. Carbomethoxy ynamides as well as more ketenophilic bissilyl ynamines and N-sulfonyl and N-phosphoryl ynamides serve as the reaction partner in the benzannulation step. In the second stage of the strategy, RCM generates benzofused nitrogen heterocycles, and various heterocyclization processes furnish highly substituted and polycyclic indoles of types that were not available by using the previous cyclobutenone-based version of the tandem strategy. PMID:24116731

Immobilized Fe (III)-doped titanium dioxide for photodegradation of dissolved organic compounds in water.

PubMed

Mwangi, Isaac W; Ngila, J Catherine; Ndungu, Patrick; Msagati, Titus A M; Kamau, Joseph N

2013-09-01

Photocatalytic degradation of dissolved organic carbon (DOC) by utilizing Fe(III)-doped TiO2 at the visible radiation range is hereby reported. The photocatalyst was immobilized on sintered glass frits with the coating done by wet method, calcinated at 500 °C and then applied in a photodegradation reactor. The addition of a transition metal dopant, Fe(III), initiated the red shift which was confirmed by UV-Vis spectroscopy, and the photocatalyst was activated by visible radiation. X-ray diffraction patterns showed that Fe(III) doping had an effect on the crystallinity of the photocatalysts. Mixtures of DOC and associated coloured solutions were degraded in first-order kinetics, showing that the degradation process was not dependent on intermediates or other species in solution. A reactor with a catalyst coating area of 12.57 cm(2) was able to degrade 0.623 mg of the dissolved material per minute. Exposure of the reactor to hostile acidic conditions and repeated use did not compromise its efficiency. It was observed that the reactor regenerates itself in the presence of visible light, and therefore, it can be re-used for more than 100 runs before the performance dropped to <95 %. The results obtained indicate that the photocatalyst reactor has a great potential of application for use in tandem with biosorbent cartridges to complement water purification methods for domestic consumption.

Adsorption of Ten Microcystin Congeners to Common Laboratory-Ware Is Solvent and Surface Dependent

PubMed Central

Altaner, Stefan; Puddick, Jonathan; Wood, Susanna A.; Dietrich, Daniel R.

2017-01-01

Cyanobacteria can produce heptapetides called microcystins (MC) which are harmful to humans due to their ability to inhibit cellular protein phosphatases. Quantitation of these toxins can be hampered by their adsorption to common laboratory-ware during sample processing and analysis. Because of their structural diversity (>100 congeners) and different physico-chemical properties, they vary in their adsorption to surfaces. In this study, the adsorption of ten different MC congeners (encompassing non-arginated to doubly-arginated congeners) to common laboratory-ware was assessed using different solvent combinations. Sample handling steps were mimicked with glass and polypropylene pipettes and vials with increasing methanol concentrations at two pH levels, before analysis by liquid chromatography-tandem mass spectrometry. We demonstrated that MC adsorb to polypropylene surfaces irrespective of pH. After eight successive pipet actions using polypropylene tips ca. 20% of the MC were lost to the surface material, which increased to 25%–40% when solutions were acidified. The observed loss was alleviated by changing the methanol (MeOH) concentration in the final solvent. The required MeOH concentration varied depending on which congener was present. Microcystins only adsorbed to glass pipettes (loss up to 30% after eight pipet actions) when in acidified aqueous solutions. The latter appeared largely dependent on the presence of ionizable groups, such as arginine residues. PMID:28383495

Thermodynamic characterization of tandem mismatches found in naturally occurring RNA

PubMed Central

Christiansen, Martha E.; Znosko, Brent M.

2009-01-01

Although all sequence symmetric tandem mismatches and some sequence asymmetric tandem mismatches have been thermodynamically characterized and a model has been proposed to predict the stability of previously unmeasured sequence asymmetric tandem mismatches [Christiansen,M.E. and Znosko,B.M. (2008) Biochemistry, 47, 4329–4336], experimental thermodynamic data for frequently occurring tandem mismatches is lacking. Since experimental data is preferred over a predictive model, the thermodynamic parameters for 25 frequently occurring tandem mismatches were determined. These new experimental values, on average, are 1.0 kcal/mol different from the values predicted for these mismatches using the previous model. The data for the sequence asymmetric tandem mismatches reported here were then combined with the data for 72 sequence asymmetric tandem mismatches that were published previously, and the parameters used to predict the thermodynamics of previously unmeasured sequence asymmetric tandem mismatches were updated. The average absolute difference between the measured values and the values predicted using these updated parameters is 0.5 kcal/mol. This updated model improves the prediction for tandem mismatches that were predicted rather poorly by the previous model. This new experimental data and updated predictive model allow for more accurate calculations of the free energy of RNA duplexes containing tandem mismatches, and, furthermore, should allow for improved prediction of secondary structure from sequence. PMID:19509311

Direct Analysis of Amphetamine Stimulants in a Whole Urine Sample by Atmospheric Solids Analysis Probe Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Crevelin, Eduardo J.; Salami, Fernanda H.; Alves, Marcela N. R.; De Martinis, Bruno S.; Crotti, Antônio E. M.; Moraes, Luiz A. B.

2016-05-01

Amphetamine-type stimulants (ATS) are among illicit stimulant drugs that are most often used worldwide. A major challenge is to develop a fast and efficient methodology involving minimal sample preparation to analyze ATS in biological fluids. In this study, a urine pool solution containing amphetamine, methamphetamine, ephedrine, sibutramine, and fenfluramine at concentrations ranging from 0.5 pg/mL to 100 ng/mL was prepared and analyzed by atmospheric solids analysis probe tandem mass spectrometry (ASAP-MS/MS) and multiple reaction monitoring (MRM). A urine sample and saliva collected from a volunteer contributor (V1) were also analyzed. The limit of detection of the tested compounds ranged between 0.002 and 0.4 ng/mL in urine samples; the signal-to-noise ratio was 5. These results demonstrated that the ASAP-MS/MS methodology is applicable for the fast detection of ATS in urine samples with great sensitivity and specificity, without the need for cleanup, preconcentration, or chromatographic separation. Thus ASAP-MS/MS could potentially be used in clinical and forensic toxicology applications.

Computational approaches to protein inference in shotgun proteomics

PubMed Central

2012-01-01

Shotgun proteomics has recently emerged as a powerful approach to characterizing proteomes in biological samples. Its overall objective is to identify the form and quantity of each protein in a high-throughput manner by coupling liquid chromatography with tandem mass spectrometry. As a consequence of its high throughput nature, shotgun proteomics faces challenges with respect to the analysis and interpretation of experimental data. Among such challenges, the identification of proteins present in a sample has been recognized as an important computational task. This task generally consists of (1) assigning experimental tandem mass spectra to peptides derived from a protein database, and (2) mapping assigned peptides to proteins and quantifying the confidence of identified proteins. Protein identification is fundamentally a statistical inference problem with a number of methods proposed to address its challenges. In this review we categorize current approaches into rule-based, combinatorial optimization and probabilistic inference techniques, and present them using integer programing and Bayesian inference frameworks. We also discuss the main challenges of protein identification and propose potential solutions with the goal of spurring innovative research in this area. PMID:23176300

Detection and quantitation of trace phenolphthalein (in pharmaceutical preparations and in forensic exhibits) by liquid chromatography-tandem mass spectrometry, a sensitive and accurate method.

PubMed

Sharma, Kakali; Sharma, Shiba P; Lahiri, Sujit C

2013-01-01

Phenolphthalein, an acid-base indicator and laxative, is important as a constituent of widely used weight-reducing multicomponent food formulations. Phenolphthalein is an useful reagent in forensic science for the identification of blood stains of suspected victims and for apprehending erring officials accepting bribes in graft or trap cases. The pink-colored alkaline hand washes originating from the phenolphthalein-smeared notes can easily be determined spectrophotometrically. But in many cases, colored solution turns colorless with time, which renders the genuineness of bribe cases doubtful to the judiciary. No method is known till now for the detection and identification of phenolphthalein in colorless forensic exhibits with positive proof. Liquid chromatography-tandem mass spectrometry had been found to be most sensitive, accurate method capable of detection and quantitation of trace phenolphthalein in commercial formulations and colorless forensic exhibits with positive proof. The detection limit of phenolphthalein was found to be 1.66 pg/L or ng/mL, and the calibration curve shows good linearity (r(2) = 0.9974). © 2012 American Academy of Forensic Sciences.

Determination of microcystin-LR in drinking water using UPLC tandem mass spectrometry-matrix effects and measurement.

PubMed

Li, Wei; Duan, Jinming; Niu, Chaoying; Qiang, Naichen; Mulcahy, Dennis

2011-10-01

A simple detection method using ultra-performance liquid chromatography electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS-MS) coupled with the sample dilution method for determining trace microcystin-LR (MC-LR) in drinking water is presented. The limit of detection (LOD) was 0.04 µg/L and the limit of quantitation (LOQ) was 0.1 µg/L. Water matrix effects of ionic strength, dissolved organic carbon (DOC) and pH were examined. The results indicate that signal detection intensity for MC-LR was significantly suppressed as the ionic strength increased from ultrapure water condition, whereas it increased slightly with solution pH and DOC at low concentrations. However, addition of methanol (MeOH) into the sample was able to counter the signal suppression effects. In this study, dilution of the tap water sample by adding 4% MeOH (v/v) was observed to be adequate to compensate for the signal suppression. The recoveries of the samples fortified with MC-LR (0.2, 1, and 10 µg/L) for three different tap water samples ranged from 84.4% to 112.9%.

QuEChERS Purification Combined with Ultrahigh-Performance Liquid Chromatography Tandem Mass Spectrometry for Simultaneous Quantification of 25 Mycotoxins in Cereals

PubMed Central

Sun, Juan; Li, Weixi; Zhang, Yan; Hu, Xuexu; Wu, Li; Wang, Bujun

2016-01-01

A method based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) purification combined with ultrahigh performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS), was optimized for the simultaneous quantification of 25 mycotoxins in cereals. Samples were extracted with a solution containing 80% acetonitrile and 0.1% formic acid, and purified with QuEChERS before being separated by a C18 column. The mass spectrometry was conducted by using positive electrospray ionization (ESI+) and multiple reaction monitoring (MRM) models. The method gave good linear relations with regression coefficients ranging from 0.9950 to 0.9999. The detection limits ranged from 0.03 to 15.0 µg·kg−1, and the average recovery at three different concentrations ranged from 60.2% to 115.8%, with relative standard deviations (RSD%) varying from 0.7% to 19.6% for the 25 mycotoxins. The method is simple, rapid, accurate, and an improvement compared with the existing methods published so far. PMID:27983693

[Separation and identification of 5 glycosidic flavor precursors in tobacco by ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry].

PubMed

Wu, Xinhua; Zhu, Ruizhi; Ren, Zhuoying; Wang, Kai; Mou, Dingrong; Wei, Wanzhi; Miao, Mingming

2009-11-01

A qualitative method for the identification of 5 main glycosidic flavor precursors in tobacco was developed by using ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI MS/MS) and gas chromatography-mass spectrometry (GC-MS). The glycosidic flavor precursors in tobacco were extracted with methanol, cleaned up with an XAD-2 column. The aglycones were later released by enzyme-mediated hydrolysis under the condition of pH 5. The 5 volatile aglycone moieties were identified by GC-MS standard spectra library. The precursor ions of glycosides were determined by using electrospray ionization mass spectrometry in negative ion mode, then the 5 glycosidic flavor precursors were identified by using product ion scan (MS2) finally, using UPLC-ESI MS/MS, separation and identification of 5 glycosidic flavor precursors were accomplished on an RP-C,8 column in the multiple reaction monitoring (MRM) mode by using methanol and acetic acid-ammonium acetate aqueous solution as eluent. This work lays a foundation for the analysis of glycosidic flavor precursors without the standards by using liquid chromatography-mass spectrometry.

Molecularly imprinted solid-phase extraction for the determination of ten macrolide drugs residues in animal muscles by liquid chromatography-tandem mass spectrometry.

PubMed

Song, Xuqin; Zhou, Tong; Liu, Qingying; Zhang, Meiyu; Meng, Chenying; Li, Jiufeng; He, Limin

2016-10-01

A simple and sensitive method based on molecularly imprinted solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry was developed for the determination of the residues of ten macrolide drugs in swine, cattle and chicken muscles samples. The molecularly imprinted polymers (MIPs) were synthesized using tylosin as a template and methacrylic acid as a functional monomer. Samples were extracted with sodium borate buffer solution and ethyl acetate, and purified by the MIP cartridge. The results showed that the cartridge exhibited good recognition performance for macrolides, and better purification effect than the traditional solid-phase extraction cartridges. Recoveries of analytes at three spiking levels 1, 5 and 20μgkg(-1) ranged from 60.7% to 100.3% with the relative standard deviations less than 14%. The limits of detection of the method were between 0.1 and 0.4μgkg(-1). The method is useful for the routine monitoring of the residues of macrolide drugs in animal muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid determination of five antibiotic residues in swine wastewater by online solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Tagiri-Endo, Misako; Suzuki, Shigeru; Nakamura, Tomoyuki; Hatakeyama, Takashi; Kawamukai, Kazuo

2009-02-01

A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS) for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin, VLM) in swine wastewater has been developed. After filtration, aliquots (100 microl) of wastewater samples were directly injected to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision was between 6 to 17%. The detection limits were 0.01-0.1 ng/ml. When this method was applied to wastewater samples in swine facilities, four compounds (LCM, OTC, TS, and VLM) were detected.

Molecular Basis for Phosphorylation-dependent SUMO Recognition by the DNA Repair Protein RAP80.

PubMed

Anamika; Spyracopoulos, Leo

2016-02-26

Recognition and repair of double-stranded DNA breaks (DSB) involves the targeted recruitment of BRCA tumor suppressors to damage foci through binding of both ubiquitin (Ub) and the Ub-like modifier SUMO. RAP80 is a component of the BRCA1 A complex, and plays a key role in the recruitment process through the binding of Lys(63)-linked poly-Ub chains by tandem Ub interacting motifs (UIM). RAP80 also contains a SUMO interacting motif (SIM) just upstream of the tandem UIMs that has been shown to specifically bind the SUMO-2 isoform. The RAP80 tandem UIMs and SIM function collectively for optimal recruitment of BRCA1 to DSBs, although the molecular basis of this process is not well understood. Using NMR spectroscopy, we demonstrate that the RAP80 SIM binds SUMO-2, and that both specificity and affinity are enhanced through phosphorylation of the canonical CK2 site within the SIM. The affinity increase results from an enhancement of electrostatic interactions between the phosphoserines of RAP80 and the SIM recognition module within SUMO-2. The NMR structure of the SUMO-2·phospho-RAP80 complex reveals that the molecular basis for SUMO-2 specificity is due to isoform-specific sequence differences in electrostatic SIM recognition modules. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Quantitation of pilsicainide in microscale samples of human biological fluids using liquid chromatography-tandem mass spectrometry.

PubMed

Shimizu, Mikiko; Hashiguchi, Masayuki; Shiga, Tsuyoshi; Nakamura, Koichi; Tamura, Hiro-omi; Mochizuki, Mayumi

2015-03-15

This paper describes a sensitive, reliable method to determine pilsicainide (PLC) levels in microscale sample volumes of human biological fluids using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). PLC and quinidine as an internal standard were extracted with diethylether from 0.1mL of alkalinized biological fluids. The extract was injected into an analytical column (l-column 2 ODS, 75mm×2.1mm i.d.). The mobile phase for separation consisted of 5mM ammonium acetate (pH 4.5)/methanol (4:1, v/v) and was delivered at a flow rate of 0.2mL/min. The drift voltage was 100V. The sampling aperture was heated at 120°C and the shield temperature was 260°C. The ion transitions used to monitor analytes were m/z 273→m/z 110 for PLC and m/z 325→m/z 79 for quinidine. The total time for chromatographic separation was less than 8min. The validated concentration ranges of this method for PLC were 5-2000ng/mL in plasma, 5-500ng/mL in ultrafiltered plasma solution, and 25-2000ng/mL in urine. Mean recoveries of PLC in plasma, ultrafiltered plasma solution, and urine were 93.2-99.7%, 91.4-100.6%, and 93.9-104.7%, respectively. Intra- and interday coefficients of variation for PLC were less than 6.0% and 4.3% in plasma, 6.1% and 3.7% in ultrafiltered plasma solution, and 5.4% and 2.5% in urine at the above concentration ranges, respectively. The lower limit of quantification for PLC in plasma, ultrafiltered plasma solution, and urine were 5ng/mL, 5ng/mL, and 25ng/mL, respectively. This method can be applied to pharmacokinetic study and therapeutic drug monitoring in special populations such as neonates, infants, and the elderly by making effective use of residual samples used for general clinical laboratory testing. Copyright © 2015 Elsevier B.V. All rights reserved.

Modeling the microstructural changes during hot tandem rolling of AA5 XXX aluminum alloys: Part I. Microstructural evolution

NASA Astrophysics Data System (ADS)

Wells, M. A.; Samarasekera, I. V.; Brimacombe, J. K.; Hawbolt, E. B.; Lloyd, D. J.

1998-06-01

A comprehensive mathematical model of the hot tandem rolling process for aluminum alloys has been developed. Reflecting the complex thermomechanical and microstructural changes effected in the alloys during rolling, the model incorporated heat flow, plastic deformation, kinetics of static recrystallization, final recrystallized grain size, and texture evolution. The results of this microstructural engineering study, combining computer modeling, laboratory tests, and industrial measurements, are presented in three parts. In this Part I, laboratory measurements of static recrystallization kinetics and final recrystallized grain size are described for AA5182 and AA5052 aluminum alloys and expressed quantitatively by semiempirical equations. In Part II, laboratory measurements of the texture evolution during static recrystallization are described for each of the alloys and expressed mathematically using a modified form of the Avrami equation. Finally, Part III of this article describes the development of an overall mathematical model for an industrial aluminum hot tandem rolling process which incorporates the microstructure and texture equations developed and the model validation using industrial data. The laboratory measurements for the microstructural evolution were carried out using industrially rolled material and a state-of-the-art plane strain compression tester at Alcan International. Each sample was given a single deformation and heat treated in a salt bath at 400 °C for various lengths of time to effect different levels of recrystallization in the samples. The range of hot-working conditions used for the laboratory study was chosen to represent conditions typically seen in industrial aluminum hot tandem rolling processes, i.e., deformation temperatures of 350 °C to 500 °C, strain rates of 0.5 to 100 seconds and total strains of 0.5 to 2.0. The semiempirical equations developed indicated that both the recrystallization kinetics and the final recrystallized grain size were dependent on the deformation history of the material i.e., total strain and Zener-Hollomon parameter ( Z), where Z = dot \\varepsilon exp left( {{Q_{def} }/{RT_{def }}} right) and time at the recrystallization temperature.

Evaluation of Wet Chemical ICP-AES Elemental Analysis Methods usingSimulated Hanford Waste Samples-Phase I Interim Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Charles J.; Edwards, Thomas B.

2005-04-30

The wet chemistry digestion method development for providing process control elemental analyses of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Melter Feed Preparation Vessel (MFPV) samples is divided into two phases: Phase I consists of: (1) optimizing digestion methods as a precursor to elemental analyses by ICP-AES techniques; (2) selecting methods with the desired analytical reliability and speed to support the nine-hour or less turnaround time requirement of the WTP; and (3) providing baseline comparison to the laser ablation (LA) sample introduction technique for ICP-AES elemental analyses that is being developed at the Savannah River National Laboratory (SRNL).more » Phase II consists of: (1) Time-and-Motion study of the selected methods from Phase I with actual Hanford waste or waste simulants in shielded cell facilities to ensure that the methods can be performed remotely and maintain the desired characteristics; and (2) digestion of glass samples prepared from actual Hanford Waste tank sludge for providing comparative results to the LA Phase II study. Based on the Phase I testing discussed in this report, a tandem digestion approach consisting of sodium peroxide fusion digestions carried out in nickel crucibles and warm mixed-acid digestions carried out in plastic bottles has been selected for Time-and-Motion study in Phase II. SRNL experience with performing this analytical approach in laboratory hoods indicates that well-trained cell operator teams will be able to perform the tandem digestions in five hours or less. The selected approach will produce two sets of solutions for analysis by ICP-AES techniques. Four hours would then be allocated for performing the ICP-AES analyses and reporting results to meet the nine-hour or less turnaround time requirement. The tandem digestion approach will need to be performed in two separate shielded analytical cells by two separate cell operator teams in order to achieve the nine-hour or less turnaround time. Because of the simplicity of the warm mixed-acid method, a well-trained cell operator team may in time be able to perform both sets of digestions. However, having separate shielded cells for each of the methods is prudent to avoid overcrowding problems that would impede a minimal turnaround time.« less

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

PubMed

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

2013-01-04

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

Stabilization of perfect and imperfect tandem repeats by single-strand DNA exonucleases

PubMed Central

Feschenko, Vladimir V.; Rajman, Luis A.; Lovett, Susan T.

2003-01-01

Rearrangements between tandemly repeated DNA sequences are a common source of genetic instability. Such rearrangements underlie several human genetic diseases. In many organisms, the mismatch-repair (MMR) system functions to stabilize repeats when the repeat unit is short or when sequence imperfections are present between the repeats. We show here that the action of single-stranded DNA (ssDNA) exonucleases plays an additional, important role in stabilizing tandem repeats, independent of their role in MMR. For perfect repeats of ≈100 bp in Escherichia coli that are not susceptible to MMR, exonuclease (Exo)-I, ExoX, and RecJ exonuclease redundantly inhibit deletion. Our data suggest that >90% of potential deletion events are avoided by the combined action of these three exonucleases. Imperfect tandem repeats, less prone to rearrangements, are stabilized by both the MMR-pathway and ssDNA-specific exonucleases. For 100-bp repeats containing four mispairs, ExoI alone aborts most deletion events, even in the presence of a functional MMR system. By genetic analysis, we show that the inhibitory effect of ssDNA exonucleases on deletion formation is independent of the MutS and UvrD proteins. Exonuclease degradation of DNA displaced during the deletion process may abort slipped misalignment. Exonuclease action is therefore a significant force in genetic stabilization of many forms of repetitive DNA. PMID:12538867

Electrical and optical analyses of tandem organic light-emitting diodes with organic charge-generation layer

NASA Astrophysics Data System (ADS)

Kim, Bong Sung; Chae, Heeyeop; Chung, Ho Kyoon; Cho, Sung Min

2018-06-01

The electrical and optical properties of tandem organic light-emitting diodes (OLEDs), in which a fluorescent and phosphorescent emitting units are connected by an organic charge-generation layer (CGL), were experimentally analyzed. To investigate the internal properties of the tandem OLEDs, we fabricated and compared two single, two homo-tandem, and two hetero-tandem OLEDs using the fluorescent and phosphorescent units. From the experimental results of the OLEDs obtained at the same current density, the voltage across the CGL as well as the individual emission spectra and luminance of each unit of tandem OLEDs were obtained and compared with the theoretical simulation results. The analysis method proposed in this study can be utilized as a method to verify the accuracy of optical or electrical computer simulation of tandem OLED and it will be useful to understand the overall electrical and optical characteristics of tandem OLEDs.

Hydrochemical processes and evolution of karst groundwater in the northeastern Huaibei Plain, China

NASA Astrophysics Data System (ADS)

Qian, Jiazhong; Peng, Yinxue; Zhao, Weidong; Ma, Lei; He, Xiaorui; Lu, YueHan

2018-06-01

Major ion geochemistry reveals that the hydrochemical evolutionary process of karst groundwater in the northeastern Huaibei Plain, China, consists of three sub-processes: the dissolution of dolomite, gypsum dissolution with dedolomitization, and mixing with overlying pore water. Understanding hydrochemical evolution has been an important topic in understanding the history, status, and dynamics of the groundwater flow system. The presented study found a hydrochemical boundary roughly corresponding to the thickness of overlying strata equating to 50 m depth, indicating two flow compartments participating in different hydrological cycles—a local shallow rapidly replenished compartment showing lower and more stable main ion concentrations, and a regional deep-flow compartment showing higher and sporadic concentrations of Na+, K+, Ca2+, Mg2+, Cl- and SO4 2-, as well as high total dissolved solids (TDS), total hardness, and sodium adsorption ratio (SAR). In areas with aquifers with low water transmitting ability, groundwater samples show a high chloride ratio and elevated TDS values, indicating salinization of groundwater due to stagnant water flows. Analyses of the data on the saturation indexes and mineral solutions, in tandem with trilinear diagram analysis and petrological observations, indicate that dedolomitization is the dominant process controlling the chemical characteristics of karst groundwater in the study area. Groundwater and pore-water mixing was also observed at the later evolutionary stage of groundwater flow, demonstrating frequent groundwater/pore-water interactions where groundwater is recharged by pore water due to lower groundwater level in the study area.

Ranked solutions to a class of combinatorial optimizations—with applications in mass spectrometry based peptide sequencing and a variant of directed paths in random media

NASA Astrophysics Data System (ADS)

Doerr, Timothy P.; Alves, Gelio; Yu, Yi-Kuo

2005-08-01

Typical combinatorial optimizations are NP-hard; however, for a particular class of cost functions the corresponding combinatorial optimizations can be solved in polynomial time using the transfer matrix technique or, equivalently, the dynamic programming approach. This suggests a way to efficiently find approximate solutions-find a transformation that makes the cost function as similar as possible to that of the solvable class. After keeping many high-ranking solutions using the approximate cost function, one may then re-assess these solutions with the full cost function to find the best approximate solution. Under this approach, it is important to be able to assess the quality of the solutions obtained, e.g., by finding the true ranking of the kth best approximate solution when all possible solutions are considered exhaustively. To tackle this statistical issue, we provide a systematic method starting with a scaling function generated from the finite number of high-ranking solutions followed by a convergent iterative mapping. This method, useful in a variant of the directed paths in random media problem proposed here, can also provide a statistical significance assessment for one of the most important proteomic tasks-peptide sequencing using tandem mass spectrometry data. For directed paths in random media, the scaling function depends on the particular realization of randomness; in the mass spectrometry case, the scaling function is spectrum-specific.

Acid-promoted Bicyclization of Diaryl Alkynes: Synthesis of 2H-Indazoles with in situ Generated Diazonium Salt as Nitrogen Source.

PubMed

Zhang, Cheng; Chang, Sailan; Dong, Shanliang; Qiu, Lihua; Xu, Xinfang

2018-06-08

An unprecedented transition-metal-free tandem bicyclization of diaryl alkynes has been disclosed, which provides a streamlined access to a range of polycyclic 2H-indazoles in high to excellent yields. The salient features of this reaction include readily available starting materials, good functional group compatibility, mild reaction conditions, no column chromatography, high bond-formation efficiency, and ease in further transformations. Notably, this is the first example for the synthesis of 2H-indazoles with in situ generated diazonium salt as the nitrogen source, and a mechanistic rationale involving an acid-promoted tandem diazonium salt formation/bicyclization process is discussed.

Monolithic Parallel Tandem Organic Photovoltaic Cell with Transparent Carbon Nanotube Interlayer

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Review of software tools for design and analysis of large scale MRM proteomic datasets.

PubMed

Colangelo, Christopher M; Chung, Lisa; Bruce, Can; Cheung, Kei-Hoi

2013-06-15

Selective or Multiple Reaction monitoring (SRM/MRM) is a liquid-chromatography (LC)/tandem-mass spectrometry (MS/MS) method that enables the quantitation of specific proteins in a sample by analyzing precursor ions and the fragment ions of their selected tryptic peptides. Instrumentation software has advanced to the point that thousands of transitions (pairs of primary and secondary m/z values) can be measured in a triple quadrupole instrument coupled to an LC, by a well-designed scheduling and selection of m/z windows. The design of a good MRM assay relies on the availability of peptide spectra from previous discovery-phase LC-MS/MS studies. The tedious aspect of manually developing and processing MRM assays involving thousands of transitions has spurred to development of software tools to automate this process. Software packages have been developed for project management, assay development, assay validation, data export, peak integration, quality assessment, and biostatistical analysis. No single tool provides a complete end-to-end solution, thus this article reviews the current state and discusses future directions of these software tools in order to enable researchers to combine these tools for a comprehensive targeted proteomics workflow. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Formate as a CO surrogate for cascade processes: Rh-catalyzed cooperative decarbonylation and asymmetric Pauson-Khand-type cyclization reactions.

PubMed

Lee, Hang Wai; Chan, Albert S C; Kwong, Fuk Yee

2007-07-07

A rhodium-(S)-xyl-BINAP complex-catalyzed tandem formate decarbonylation and [2 + 2 + 1] carbonylative cyclization is described; this cooperative process utilizes formate as a condensed CO source, and the newly developed cascade protocol can be extended to its enantioselective version, providing up to 94% ee of the cyclopentenone adducts.

Elution of Re-188 from W-188/Re-188 generators with salts of weak acids permits efficient concentration to low volumes using a new tandem cation/anion exchange system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guhlke, S.; Beets, A.L.; Knapp, F.F. Jr.

1997-05-01

Re-188, available from a W-188/Re-188 generator, is an important therapeutic radioisotope for bone pain palliation, cancer therapy and intravascular brachytherapy, etc. Because of the relatively low specific activity of reactor-produced W-188 (ORNL HFIR, 296-370 MBq mCi/mg W-186 for 2 cycles), methods of concentrating the Re-188 bolus (10-12 mL) from clinical scale (18.5-37 BGq W-188) generators (5-6 gm alumina) are thus very important. We demonstrate for the first time a new strategy of generator elution with salts of weak acids and specific perrhenate anion {open_quotes}trapping{close_quotes} with QMA anion columns. Re-188 perrhenate is efficiently eluted (65-75%) from the alumina-based generator with 0.15-0.3more » M ammonium acetate. An acetic acid solution of Re-188 perrhenic acid is obtained by subsequent on-line passage of the generator eluant through a DOWEX AG 50Wx8 (200-400 mesh, H{sup +} form) column. Since acetic acid is not ionized (< 0.001%) at this pH (< pK{sub a} = 4.76) the perrhenate anion is then specifically trapped on a QMA {open_quotes}Light{close_quotes} anion extraction column. QMA elution with 0.9% NaCl, provides Re-188 perrhenate solution in <1 mL. Concentration of 10-20 mL of Re-188 solution (> 15 BGq) in <1 mL has been demonstrated using this simple new approach, which is also effective for concentration of Tc-99m from low specific activity Mo-99 (n,y) generators. The cation/anion tandem system is inexpensive and disposable and use can be easily automated. The availability of this very simple, efficient system is important for broad use of rhenium-188.« less

[Determination of myclobutanil and difenoconazole residues in pollen and honey of litchi by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Wang, Siwei; Liu, Yanping; Sun, Haibin; DU, Lanjuan; Xu, Nengli

2018-01-08

An effective method was developed for the determination of two major fungicides including myclobutanil and difenoconazole residues in pollen and honey of litchi by modified QuEChERS-high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The pollen and honey samples were all extracted by acetonitrile, the pollen samples were cleaned-up by 0.9 g anhydrous magnesium sulfate (MgSO 4 ), 0.15 g primary secondary amine (PSA) and 0.15 g C 18 ; the honey samples were cleaned-up by 0.9 g MgSO 4 and 0.15 g PSA. The 0.1% (v/v) formic acid aqueous solution-acetonitrile (25:75, v/v) were used as the mobile phases. The extracts were separated on a Poroshell-120 EC-C 18 chromatographic column, the positive electrospray ion (ESI + ) source and selected ion monitoring (SIM) mode were used. The analytes were quantified by the matrix matching standard solutions. The matrix matched standard solutions of myclobutanil and difenoconazole showed good linearities in the range of 1-100 μg/L, and the correlation coefficients ( r 2 ) were all above 0.9990. The limits of detection (LODs) of myclobutanil and difenoconazole were 0.25 μg/kg and 0.50 μg/kg, respectively. The limits of quantification (LOQs) of myclobutanil and difenoconazole were 0.83 μg/kg and 1.7 μg/kg, respectively. The average recoveries of myclobutanil and difenoconazole in pollen and honey samples were 87.0%-95.2% and 90.1%-96.4% with the relative standard deviations of 1.2%-3.6% and 0.7%-4.1%, respectively. The method is quick, easy and sensitive, and it is suitable for the rapid determination and trace analysis of myclobutanil and difenoconazole in pollens and honeys of litchi. The method can provide data support for the exposure risk assessment of bees and other pollination insects.

Comparison analysis in growth process in Asian cities by using tandem time series remote sensing of different satellite

NASA Astrophysics Data System (ADS)

Hashiba, Hideki; Nakayama, Yasunori; Sugimura, Toshiro

The growth of major cities in Asia, as a consequence of economic development, is feared to have adverse influences on the natural environment of the surrounding areas. Comparison of land cover changes in major cities from the viewpoints of both spatial and time series is necessary to fully understand the characteristics of urban development in Asia. To accomplish this, multiple satellite remote sensing data were analyzed across a wide range and over a long term in this study. The process of transition of a major Asian city in Tokyo, Osaka, Beijing, Shanghai, and Hong Kong was analyzed from the characteristic changes of the vegetation index value and the land cover over about 40 years, from 1972 to 2010. Image data for LANDSAT/MSS, LAND-SAT/TM, ALOS/AVNIR-2, and ALOS/PRISM were obtained using a tandem time series. The ratio and state of detailed distribution of land cover were clarified by the classification processing. The time series clearly showed different change characteristics for each city and its surrounding natural environment of vegetation and forest etc. as a result of development processes.

The kinetic stabilizer: a route to simpler tandem mirror systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, R F

2001-02-02

As we enter the new millennium there is a growing urgency to address the issue of finding long-range solutions to the world's energy needs. Fusion offers such a solution, provided economically viable means can be found to extract useful energy from fusion reactions. While the magnetic confinement approach to fusion has a long and productive history, to date the mainline approaches to magnetic confinement, namely closed systems such as the tokamak, appear to many as being too large and complex to be acceptable economically, despite the impressive progress that has made toward the achievement of fusion-relevant confinement parameters. Thus theremore » is a growing feeling that it is imperative to search for new and simpler approaches to magnetic fusion, ones that might lead to smaller and more economically attractive fusion power plants.« less

Combined deficiency of MSH2 and Sμ region abolishes class switch recombination.

PubMed

Leduc, Claire; Haddad, Dania; Laviolette-Malirat, Nathalie; Nguyen Huu, Ngoc-Sa; Khamlichi, Ahmed Amine

2010-10-01

Class switch recombination (CSR) is mediated by G-rich tandem repeated sequences termed switch regions. Transcription of switch regions generates single-stranded R loops that provide substrates for activation-induced cytidine deaminase. Mice deficient in MSH2 have a mild defect in CSR and analysis of their switch junctions has led to a model in which MSH2 is more critical for switch recombination events outside than within the tandem repeats. It is also known that deletion of the whole Sμ region severely impairs but does not abrogate CSR despite the lack of detectable R loops. Here, we demonstrate that deficiency of both MSH2 and the Sμ region completely abolishes CSR and that the abrogation occurs at the genomic level. This finding further supports the crucial role of MSH2 outside the tandem repeats. It also indicates that during CSR, MSH2 has access to activation-induced cytidine deaminase targets in R-loop-deficient Iμ-Cμ sequences rarely used in CSR, suggesting an MSH2-dependent DNA processing activity at the Iμ exon that may decrease with transcription elongation across the Sμ region.

Synthesis of extended polycyclic aromatic hydrocarbons by oxidative tandem spirocyclization and 1,2-aryl migration

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Xu, Zhanqiang; Si, Weili; Oniwa, Kazuaki; Bao, Ming; Yamamoto, Yoshinori; Jin, Tienan

2017-04-01

The extended polycyclic aromatic hydrocarbons (PAHs) have received significant interdisciplinary attention due to their semiconducting applications in diverse organic electronics as well as intriguing structural interests of well-defined graphene segments. Herein, a highly efficient oxidative spirocyclization and 1,2-aryl migration tandem synthetic method for the construction of extended polyaromatic hydrocarbons (PAHs) has been developed. The CuCl-catalyst/PhCO3 tBu or DDQ oxidation system in the presence of trifluoroacetic acid enables the selective single-electron oxidation to take place preferentially at the more electron-rich alkene moiety of o-biphenylyl-substituted methylenefluorenes, giving rise to the subsequent tandem process. A variety of structurally diverse extended PAHs including functionalized dibenzo[g,p]chrysenes, benzo[f]naphtho[1,2-s]picene, hexabenzo[a,c,fg,j,l,op]tetracene, tetrabenzo[a,c,f,m]phenanthro[9,10-k]tetraphene, tetrabenzo[a,c,f,k]phenanthro[9,10-m]tetraphene, tetrabenzo[a,c,f,o]phenanthro[9,10-m]picene and S-type helicene have been readily synthesized.

High voltage series connected tandem junction solar battery

DOEpatents

Hanak, Joseph J.

1982-01-01

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

The structure and dynamics of tandem WW domains in a negative regulator of notch signaling, Suppressor of deltex.

PubMed

Fedoroff, Oleg Y; Townson, Sharon A; Golovanov, Alexander P; Baron, Martin; Avis, Johanna M

2004-08-13

WW domains mediate protein recognition, usually though binding to proline-rich sequences. In many proteins, WW domains occur in tandem arrays. Whether or how individual domains within such arrays cooperate to recognize biological partners is, as yet, poorly characterized. An important question is whether functional diversity of different WW domain proteins is reflected in the structural organization and ligand interaction mechanisms of their multiple domains. We have determined the solution structure and dynamics of a pair of WW domains (WW3-4) from a Drosophila Nedd4 family protein called Suppressor of deltex (Su(dx)), a regulator of Notch receptor signaling. We find that the binding of a type 1 PPPY ligand to WW3 stabilizes the structure with effects propagating to the WW4 domain, a domain that is not active for ligand binding. Both WW domains adopt the characteristic triple-stranded beta-sheet structure, and significantly, this is the first example of a WW domain structure to include a domain (WW4) lacking the second conserved Trp (replaced by Phe). The domains are connected by a flexible linker, which allows a hinge-like motion of domains that may be important for the recognition of functionally relevant targets. Our results contrast markedly with those of the only previously determined three-dimensional structure of tandem WW domains, that of the rigidly oriented WW domain pair from the RNA-splicing factor Prp40. Our data illustrate that arrays of WW domains can exhibit a variety of higher order structures and ligand interaction mechanisms.

Pilot study of newborn screening of inborn error of metabolism using tandem mass spectrometry in Malaysia: outcome and challenges.

PubMed

Yunus, Zabedah Md; Rahman, Salina Abdul; Choy, Yew Sing; Keng, Wee Teik; Ngu, Lock Hock

2016-09-01

The aim of this study was to determine the feasibility of performing newborn screening (NBS) of inborn errors of metabolism (IEMs) using tandem mass spectrometry (TMS) and the impact on its detection rate in Malaysia. During the study period between June 2006 and December 2008, 30,247 newborns from 11 major public hospitals in Malaysia were screened for 27 inborn errors of amino acid, organic acid and fatty acid metabolism by TMS. Dried blood spot (DBS) samples were collected between 24 h and 7 days with parental consent. Samples with abnormal results were repeated and the babies were recalled to confirm the diagnosis with follow-up testing. Cut-off values for amino acids and acylcarnitines were established. Eight newborns were confirmed to have IEM: two newborns with Maple syrup urine disease (MSUD), two with methylmalonic aciduria (MMA) one with ethylmalonic aciduria, two with argininosuccinic aciduria and one with isovaleric aciduria. Diagnosis was missed in two newborns. The detection rate of IEMs in this study was one in 2916 newborns. The sensitivity and specificity of TMS were 80% and 99%, respectively. IEMs are common in Malaysia. NBS of IEMs by TMS is a valuable preventive strategy by enabling the diagnosis and early treatment of IEM before the onset of symptoms aiming at prevention of mental retardation and physical handicap. A number of shortcomings warrant further solution so that in near future NBS for IEMs will become a standard of care for all babies in Malaysia in tandem with the developed world.

Quantitative determination of risperidone, paliperidone and olanzapine in human serum by liquid chromatography-tandem mass spectrometry coupled with on-line solid-phase extraction.

PubMed

Ruan, Can-Jun; Guo, Wei; Zhou, Miao; Guo, Gui-Xin; Wang, Chuan-Yue; Li, Wen-Biao; de Leon, Jose

2018-07-01

A recent guideline recommends therapeutic drug monitoring for risperidone, paliperidone and olanzapine, which are frequently used second-generation antipsychotics. We developed a simple high-performance liquid chromatography-tandem mass spectrometry coupled with an online solid-phase extraction method that can be used to measure risperidone, paliperidone and olanzapine using small (40 μL) samples. The analytes were extracted from serum samples automatically pre-concentrated and purified by C 8 (5 μm, 2.1 × 30 mm) solid-phase extraction cartridges, then chromatographed on an Xbidge™ C 18 column (3.5 μm, 100 × 2.1 mm) thermostatted at 30°C with a mobile phase consisting of 70% acetonitrile and 30% ammonium hydroxide 1% solution at an isocratic flow rate of 0.3 mL/min, and detected with tandem mass spectrometry. The assay was validated in the concentration range from 2.5 to 160 ng/mL. Intra- and inter-day precision for all analytes was between 1.1 and 8.2%; method accuracy was between 6.6 and 7.6%. The risperidone and paliperidone assay was compared with a high-performance liquid chromatography-ultraviolet assay currently used in our hospital for risperidone and paliperidone therapeutic drug monitoring, and the results of weighted Deming regression analysis showed good agreement. For the olanzapine assay, we compared 20 samples in separate re-assays on different days; all the relative errors were within the 20% recommended limit. Copyright © 2018 John Wiley & Sons, Ltd.

TRedD—A database for tandem repeats over the edit distance

PubMed Central

Sokol, Dina; Atagun, Firat

2010-01-01

A ‘tandem repeat’ in DNA is a sequence of two or more contiguous, approximate copies of a pattern of nucleotides. Tandem repeats are common in the genomes of both eukaryotic and prokaryotic organisms. They are significant markers for human identity testing, disease diagnosis, sequence homology and population studies. In this article, we describe a new database, TRedD, which contains the tandem repeats found in the human genome. The database is publicly available online, and the software for locating the repeats is also freely available. The definition of tandem repeats used by TRedD is a new and innovative definition based upon the concept of ‘evolutive tandem repeats’. In addition, we have developed a tool, called TandemGraph, to graphically depict the repeats occurring in a sequence. This tool can be coupled with any repeat finding software, and it should greatly facilitate analysis of results. Database URL: http://tandem.sci.brooklyn.cuny.edu/ PMID:20624712

Multi-allergen Quantitation and the Impact of Thermal Treatment in Industry-Processed Baked Goods by ELISA and Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Parker, Christine H; Khuda, Sefat E; Pereira, Marion; Ross, Mark M; Fu, Tong-Jen; Fan, Xuebin; Wu, Yan; Williams, Kristina M; DeVries, Jonathan; Pulvermacher, Brian; Bedford, Binaifer; Zhang, Xi; Jackson, Lauren S

2015-12-16

Undeclared food allergens account for 30-40% of food recalls in the United States. Compliance with ingredient labeling regulations and the implementation of effective manufacturing allergen control plans require the use of reliable methods for allergen detection and quantitation in complex food products. The objectives of this work were to (1) produce industry-processed model foods incurred with egg, milk, and peanut allergens, (2) compare analytical method performance for allergen quantitation in thermally processed bakery products, and (3) determine the effects of thermal treatment on allergen detection. Control and allergen-incurred cereal bars and muffins were formulated in a pilot-scale industry processing facility. Quantitation of egg, milk, and peanut in incurred baked goods was compared at various processing stages using commercial enzyme-linked immunosorbent assay (ELISA) kits and a novel multi-allergen liquid chromatography (LC)-tandem mass spectrometry (MS/MS) multiple-reaction monitoring (MRM) method. Thermal processing was determined to negatively affect the recovery and quantitation of egg, milk, and peanut to different extents depending on the allergen, matrix, and analytical test method. The Morinaga ELISA and LC-MS/MS quantitative methods reported the highest recovery across all monitored allergens, whereas the ELISA Systems, Neogen BioKits, Neogen Veratox, and R-Biopharm ELISA Kits underperformed in the determination of allergen content of industry-processed bakery products.

Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.

PubMed

Jeong, Yu-Dong; Kim, Min Kyung; Suh, Sung Ill; In, Moon Kyo; Kim, Jin Young; Paeng, Ki-Jung

2015-12-01

Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully verified with human urine samples from drug users (n=21). Direct urine sample injection and optimized mobile phases were introduced for simple sample preparation and high-sensitivity with the desired separation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

SU-E-T-208: Comparison of MR Image Quality of Various Brachytherapy Applicators for Cervical Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soliman, A; Elzibak, A; Fatemi, A

2015-06-15

Purpose: To compare the quality of Magnetic Resonance (MR) images of a recently-proposed novel direction-modulated brachytherapy (DMBT) tandem applicator against two conventional clinical applicators, using the current MRI clinical protocol. Methods: Three tandem applicators were compared: (1) tungsten-based DMBT applicator, (2) conventional plastic applicator and (3) conventional stainless steel applicator. Physical dimensions were 5.4, 3.8 and 3.2 for tandems (1), (2) and (3), respectively. Each applicator was placed in the same water-phantom and independently scanned using the same parameters and coil settings on a 1.5 T 450w GE scanner. Images were acquired using T2-weighted turbo-spin-echo (TSE) with 8-channel body coil.more » Acquisition parameters were TR/TE =7000/108 ms; acquisition matrix = 320 x 256; 30 slices with 4 mm thickness and 0.5 gap; pixel bandwidth = 122 Hz and voxel size = 0.5 x 0.625 mm2 and number of excitations (NEX) = 4. Multiple acquisitions were obtained in para-sagittal and para-axial views (with respect to the tandem axis) for each applicator. Diameters of the tandem were measured at multiple angles and multiple locations and compared to the physical dimensions of the corresponding tandems. Results: Minimal susceptibility artifact was observed with the DMBT and the plastic tandems. The stainless steel tandem produced significantly larger artifact than the first two tandems. The average diameter of the DMBT applicator measured 5.94 ± 0.3 mm. The average diameter of the plastic tandem measured 3.9 ± 0.1 mm. The maximum extent of artifact was 1.5 mm and 0.7 mm for DMBT and plastic tandems, respectively. The susceptibility artifact induced by the stainless steel tandem prevented the measurement of its diameter, and the edges of the tandem could not be identified in any acquisition. Conclusion: This work demonstrated that the plastic and the tungsten-based DMBT tandem applicators are both suitable for MRI-guided brachytherapy of cervical cancer.« less

Advances in ultra-high performance liquid chromatography coupled to tandem mass spectrometry for sensitive detection of several food allergens in complex and processed foodstuffs.

PubMed

Planque, M; Arnould, T; Dieu, M; Delahaut, P; Renard, P; Gillard, N

2016-09-16

Sensitive detection of food allergens is affected by food processing and foodstuff complexity. It is therefore a challenge to detect cross-contamination in food production that could endanger an allergic customer's life. Here we used ultra-high performance liquid chromatography coupled to tandem mass spectrometry for simultaneous detection of traces of milk (casein, whey protein), egg (yolk, white), soybean, and peanut allergens in different complex and/or heat-processed foodstuffs. The method is based on a single protocol (extraction, trypsin digestion, and purification) applicable to the different tested foodstuffs: chocolate, ice cream, tomato sauce, and processed cookies. The determined limits of quantitation, expressed in total milk, egg, peanut, or soy proteins (and not soluble proteins) per kilogram of food, are: 0.5mg/kg for milk (detection of caseins), 5mg/kg for milk (detection of whey), 2.5mg/kg for peanut, 5mg/kg for soy, 3.4mg/kg for egg (detection of egg white), and 30.8mg/kg for egg (detection of egg yolk). The main advantage is the ability of the method to detect four major food allergens simultaneously in processed and complex matrices with very high sensitivity and specificity. Copyright © 2016 Elsevier B.V. All rights reserved.

47 CFR 69.129 - Signalling for tandem switching.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 3 2011-10-01 2011-10-01 false Signalling for tandem switching. 69.129 Section... (CONTINUED) ACCESS CHARGES Computation of Charges § 69.129 Signalling for tandem switching. A charge that is... provision of signalling for tandem switching. [59 FR 32930, June 27, 1994] ...

47 CFR 69.129 - Signalling for tandem switching.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 3 2010-10-01 2010-10-01 false Signalling for tandem switching. 69.129 Section... (CONTINUED) ACCESS CHARGES Computation of Charges § 69.129 Signalling for tandem switching. A charge that is... provision of signalling for tandem switching. [59 FR 32930, June 27, 1994] ...

47 CFR 69.129 - Signalling for tandem switching.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 3 2013-10-01 2013-10-01 false Signalling for tandem switching. 69.129 Section... (CONTINUED) ACCESS CHARGES Computation of Charges § 69.129 Signalling for tandem switching. A charge that is... provision of signalling for tandem switching. [59 FR 32930, June 27, 1994] ...

47 CFR 69.129 - Signalling for tandem switching.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 3 2012-10-01 2012-10-01 false Signalling for tandem switching. 69.129 Section... (CONTINUED) ACCESS CHARGES Computation of Charges § 69.129 Signalling for tandem switching. A charge that is... provision of signalling for tandem switching. [59 FR 32930, June 27, 1994] ...

PTGBase: an integrated database to study tandem duplicated genes in plants.

PubMed

Yu, Jingyin; Ke, Tao; Tehrim, Sadia; Sun, Fengming; Liao, Boshou; Hua, Wei

2015-01-01

Tandem duplication is a wide-spread phenomenon in plant genomes and plays significant roles in evolution and adaptation to changing environments. Tandem duplicated genes related to certain functions will lead to the expansion of gene families and bring increase of gene dosage in the form of gene cluster arrays. Many tandem duplication events have been studied in plant genomes; yet, there is a surprising shortage of efforts to systematically present the integration of large amounts of information about publicly deposited tandem duplicated gene data across the plant kingdom. To address this shortcoming, we developed the first plant tandem duplicated genes database, PTGBase. It delivers the most comprehensive resource available to date, spanning 39 plant genomes, including model species and newly sequenced species alike. Across these genomes, 54 130 tandem duplicated gene clusters (129 652 genes) are presented in the database. Each tandem array, as well as its member genes, is characterized in complete detail. Tandem duplicated genes in PTGBase can be explored through browsing or searching by identifiers or keywords of functional annotation and sequence similarity. Users can download tandem duplicated gene arrays easily to any scale, up to the complete annotation data set for an entire plant genome. PTGBase will be updated regularly with newly sequenced plant species as they become available. © The Author(s) 2015. Published by Oxford University Press.

Applying design principles to fusion reactor configurations for propulsion in space

NASA Technical Reports Server (NTRS)

Carpenter, Scott A.; Deveny, Marc E.; Schulze, Norman R.

1993-01-01

The application of fusion power to space propulsion requires rethinking the engineering-design solution to controlled-fusion energy. Whereas the unit cost of electricity (COE) drives the engineering-design solution for utility-based fusion reactor configurations; initial mass to low earth orbit (IMLEO), specific jet power (kW(thrust)/kg(engine)), and reusability drive the engineering-design solution for successful application of fusion power to space propulsion. We applied three design principles (DP's) to adapt and optimize three candidate-terrestrial-fusion-reactor configurations for propulsion in space. The three design principles are: provide maximum direct access to space for waste radiation, operate components as passive radiators to minimize cooling-system mass, and optimize the plasma fuel, fuel mix, and temperature for best specific jet power. The three candidate terrestrial fusion reactor configurations are: the thermal barrier tandem mirror (TBTM), field reversed mirror (FRM), and levitated dipole field (LDF). The resulting three candidate space fusion propulsion systems have their IMLEO minimized and their specific jet power and reusability maximized. We performed a preliminary rating of these configurations and concluded that the leading engineering-design solution to space fusion propulsion is a modified TBTM that we call the Mirror Fusion Propulsion System (MFPS).

Rapid method for quantification of seven synthetic pigments in colored Chinese steamed buns using UFLC-MS/MS without SPE.

PubMed

Gao, He-Gang; Gong, Wen-Jie; Zhao, Yong-Gang

2015-01-01

Synthetic pigments are still used instead of natural pigments in many foods and their residues in food could be an important risk to human health. A simple and rapid analytical method combining the low-cost extraction protocol with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of seven synthetic pigments used in colored Chinese steamed buns. For the first time, ethanol/ammonia solution/water (7:2:1, v/v/v) was used as extraction solution for the synthetic pigments in colored Chinese steamed buns. The results showed that the property of the extraction solution used in this method was more effective than critic acid solution, which is used in the polyamide adsorption method. The limits of quantification for the seven synthetic pigments ranged from 0.15 to 0.50 μg/kg. The present method was successfully applied to samples of colored Chinese steamed buns for food-safety risk monitoring in Zhejiang Province, China. The results found sunset yellow pigment in six out of 300 colored Chinese steamed buns (from 0.50 to 32.6 μg/kg).

Tandem alternative polyadenylation events of genes in non-eosinophilic nasal polyp tissue identified by high-throughput sequencing analysis

PubMed Central

TIAN, PENG; LI, JIE; LIU, XIANG; LI, YUXI; CHEN, MEIHENG; MA, YUN; ZHENG, YI QING; FU, YONGGUI; ZOU, HUA

2014-01-01

Nasal polyps (NP) is highly associated with the disorder of immune cells. Alternative polyadenylation (APA) produces mRNA isoforms with different length of 3′-untranslated region (UTR) and regulates gene expression. It has been proven that this APA-mediated regulation of 3′UTR length is an immune-associated phenomenon. The aim of this study was to investigate the genome-wide alternative tandem 3′UTR length switching events in non-eosinophilic nasal polyp tissue. Thirteen patients diagnosed as having non-eosinophilic nasal polyps were included in this study. Nasal polyp tissue and control mucosa were collected during surgery. The 3′ end library of cDNA was constructed. The recovered libraries were sequenced with second sequencing technology, and the sequencing data were analyzed by an in-house bioinformatics pipeline. Tandem 3′UTR length switching between samples was detected by a test of linear trend alternative to independence. We found a significant alteration in the tandem 3′UTR length in 1,920 genes in nasal polyp samples. Functional annotation results showed that several gene ontology (GO) terms were enriched in the list of genes with switched APA sites, including regulation of transcription, macromolecule catabolic localization and mRNA processing. The results suggested that APA-mediated alternative 3′UTR regulation plays an important role in the post-transcriptional regulation of gene expression in non-eosinophilic nasal polyps. PMID:24715051

Characterization of Conserved Tandem Donor Sites and Intronic Motifs Required for Alternative Splicing in Corticosteroid Receptor Genes

PubMed Central

Qian, Xiaoxiao; Matthews, Laura; Lightman, Stafford; Ray, David; Norman, Michael

2015-01-01

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 GRγ 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 GRγ 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

Ion/Neutral, Ion/Electron, Ion/Photon, and Ion/Ion Interactions in Tandem Mass Spectrometry: Do we need them all? Are they enough?

PubMed Central

McLuckey, Scott A.; Mentinova, Marija

2011-01-01

A range of strategies and tools has been developed to facilitate the determination of primary structures of analyte molecules of interest via tandem mass spectrometry (MS/MS). The two main factors that determine the primary structural information present in an MS/MS spectrum are the type of ion generated from the analyte molecule and the dissociation method. The ion-type subjected to dissociation is determined by the ionization method/conditions and ion transformation processes that might take place after initial gas-phase ion formation. Furthermore, the range of analyte-related ion types can be expanded via derivatization reactions prior to mass spectrometry. Dissociation methods include those that simply alter the population of internal states of the mass-selected ion (i.e., activation methods like collision-induced dissociation) as well as processes that rely on transformation of the ion-type prior to dissociation (e.g., electron capture dissociation). A variety of ionic interactions has been studied for the purpose of ion dissociation and ion transformation that include ion/neutral, ion/photon, ion/electron, and ion/ion interactions. A wide range of phenomena has been observed, many of which have been explored/developed as means for structural analysis. The techniques arising from these phenomena are discussed within the context of the elements of structure determination in tandem mass spectrometry, viz., ion-type definition and dissociation. Unique aspects of the various ion interactions are emphasized along with any barriers to widespread implementation. PMID:21472539

A somatic-mutational process recurrently duplicates germline susceptibility loci and tissue-specific super-enhancers in breast cancers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glodzik, Dominik; Morganella, Sandro; Davies, Helen

Somatic rearrangements contribute to the mutagenized landscape of cancer genomes. Here, we systematically interrogated rearrangements in 560 breast cancers by using a piecewise constant fitting approach. We identified 33 hotspots of large (>100 kb) tandem duplications, a mutational signature associated with homologous-recombination-repair deficiency. Notably, these tandem-duplication hotspots were enriched in breast cancer germline susceptibility loci (odds ratio (OR) = 4.28) and breast-specific 'super-enhancer' regulatory elements (OR = 3.54). These hotspots may be sites of selective susceptibility to double-strand-break damage due to high transcriptional activity or, through incrementally increasing copy number, may be sites of secondary selective pressure. Furthermore, the transcriptomicmore » consequences ranged from strong individual oncogene effects to weak but quantifiable multigene expression effects. We thus present a somatic-rearrangement mutational process affecting coding sequences and noncoding regulatory elements and contributing a continuum of driver consequences, from modest to strong effects, thereby supporting a polygenic model of cancer development.« less

A somatic-mutational process recurrently duplicates germline susceptibility loci and tissue-specific super-enhancers in breast cancers

DOE PAGES

Glodzik, Dominik; Morganella, Sandro; Davies, Helen; ...

2017-01-23

Somatic rearrangements contribute to the mutagenized landscape of cancer genomes. Here, we systematically interrogated rearrangements in 560 breast cancers by using a piecewise constant fitting approach. We identified 33 hotspots of large (>100 kb) tandem duplications, a mutational signature associated with homologous-recombination-repair deficiency. Notably, these tandem-duplication hotspots were enriched in breast cancer germline susceptibility loci (odds ratio (OR) = 4.28) and breast-specific 'super-enhancer' regulatory elements (OR = 3.54). These hotspots may be sites of selective susceptibility to double-strand-break damage due to high transcriptional activity or, through incrementally increasing copy number, may be sites of secondary selective pressure. Furthermore, the transcriptomicmore » consequences ranged from strong individual oncogene effects to weak but quantifiable multigene expression effects. We thus present a somatic-rearrangement mutational process affecting coding sequences and noncoding regulatory elements and contributing a continuum of driver consequences, from modest to strong effects, thereby supporting a polygenic model of cancer development.« less

Identification of specific bovine blood biomarkers with a non-targeted approach using HPLC ESI tandem mass spectrometry.

PubMed

Lecrenier, M C; Marbaix, H; Dieu, M; Veys, P; Saegerman, C; Raes, M; Baeten, V

2016-12-15

Animal by-products are valuable protein sources in animal nutrition. Among them are blood products and blood meal, which are used as high-quality material for their beneficial effects on growth and health. Within the framework of the feed ban relaxation, the development of complementary methods in order to refine the identification of processed animal proteins remains challenging. The aim of this study was to identify specific biomarkers that would allow the detection of bovine blood products and processed animal proteins using tandem mass spectrometry. Seventeen biomarkers were identified: nine peptides for bovine plasma powder; seven peptides for bovine haemoglobin powder, including six peptides for bovine blood meal; and one peptide for porcine blood. They were not detected in several commercial compound feed or feed materials, such as blood by-products of other animal origins, milk-derived products and fish meal. These biomarkers could be used for developing a species-specific and blood-specific detection method. Copyright © 2016 Elsevier Ltd. All rights reserved.

An Integration, Long Range Planning, and Migration Guide for the Stock Point Logistics Integrated Communications Project.

DTIC Science & Technology

1986-03-01

and universal terminal/printer interface mapping ( TMAP ) software. When the Burroughs HYPERchannel software package (i.e., Burroughs NETEX) provided...and terminal device and security functions placed under the control of the FDC’s SAS/ TMAP processes. Without processing efficiency enhancements, TAPS...FDC’s SAS/ TMAP processes. As was also previously indicated, the performance of TAPS II on TANDEM is poor today, and there are questions as whether

A Tandem Microscopic-Electrochemical Examination of A Charge-Induced Surface Phase Sequence: Ordered Au(110) in Aqueous Iodide Electrolytes as Probed by Potentiodynamic Scanning Tunneling Microscopy

DTIC Science & Technology

1994-02-01

and Rh(lll)9-12 by STM, and halides on Au(lll) by SXRS. 1 3 ’ 1 4 For several of these systems, especially anion adsorption on gold , the adsorbate...index faces of gold in aqueous solution by means of in- situ STM combined with conventional electrochemical methods. The value of the electrochemical...structure and conversion dynamics. A related description of the Au(lO0)-I- system, along with a comparison with the behavior of the other two low-index gold

Proteus DSA control room in Mojave, CA

NASA Image and Video Library

2003-04-03

Proteus DSA control room in Mojave, CA (L to R) Jean-Pierre Soucy; Amphitech International Software engineer Craig Bomben; NASA Dryden Test Pilot Pete Siebold; (with headset, at computer controls) Scaled Composites pilot Bob Roehm; New Mexico State University (NMSU) UAV Technical Analysis Application Center (TAAC) Chuck Coleman; Scaled Composites Pilot Kari Sortland; NMSU TAAC Russell Wolfe; Modern Technology Solutions, Inc. Scaled Composites' unique tandem-wing Proteus was the testbed for a series of UAV collision-avoidance flight demonstrations. An Amphitech 35GHz radar unit installed below Proteus' nose was the primary sensor for the Detect, See and Avoid tests.

Selecting tandem partners for silicon solar cells [Selecting tandem partners for silicon solar cells using spectral efficiency

DOE PAGES

Yu, Zhengshan; Leilaeioun, Mehdi; Holman, Zachary

2016-09-26

Combining silicon and other materials in tandem solar cells is one approach to enhancing the overall power conversion efficiency of the cells. Here, we argue that top cell partners for silicon tandem solar cells should be selected on the basis of their spectral efficiency — their efficiency resolved by wavelength.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-12

...] Vertical Tandem Lifts in Marine Terminals; Extension of the Office of Management and Budget's (OMB... Standard on Vertical Tandem Lifts (VTLs) in Marine Terminals (29 CFR part 1917). The collection of... on Vertical Tandem Lifts for Marine Terminals (29 CFR part 1917). OSHA is proposing to increase the...

Selecting tandem partners for silicon solar cells [Selecting tandem partners for silicon solar cells using spectral efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Zhengshan; Leilaeioun, Mehdi; Holman, Zachary

Combining silicon and other materials in tandem solar cells is one approach to enhancing the overall power conversion efficiency of the cells. Here, we argue that top cell partners for silicon tandem solar cells should be selected on the basis of their spectral efficiency — their efficiency resolved by wavelength.

A Silicon–Singlet Fission Tandem Solar Cell Exceeding 100% External Quantum Efficiency with High Spectral Stability

PubMed Central

2017-01-01

After 60 years of research, silicon solar cell efficiency saturated close to the theoretical limit, and radically new approaches are needed to further improve the efficiency. The use of tandem systems raises this theoretical power conversion efficiency limit from 34% to 45%. We present the advantageous spectral stability of using voltage-matched tandem solar cells with respect to their traditional series-connected counterparts and experimentally demonstrate how singlet fission can be used to produce simple voltage-matched tandems. Our singlet fission silicon–pentacene tandem solar cell shows efficient photocurrent addition. This allows the tandem system to benefit from carrier multiplication and to produce an external quantum efficiency exceeding 100% at the main absorption peak of pentacene. PMID:28261671

All-Ambient Processed Binary CsPbBr3-CsPb2Br5 Perovskites with Synergistic Enhancement for High-Efficiency Cs-Pb-Br-Based Solar Cells.

PubMed

Zhang, Xisheng; Jin, Zhiwen; Zhang, Jingru; Bai, Dongliang; Bian, Hui; Wang, Kang; Sun, Jie; Wang, Qian; Liu, Shengzhong Frank

2018-02-28

All-inorganic CsPbBr 3 perovskite solar cells display outstanding stability toward moisture, light soaking, and thermal stressing, demonstrating great potential in tandem solar cells and toward commercialization. Unfortunately, it is still challenging to prepare high-performance CsPbBr 3 films at moderate temperatures. Herein, a uniform, compact CsPbBr 3 film was fabricated using its quantum dot (QD)-based ink precursor. The film was then treated using thiocyanate ethyl acetate (EA) solution in all-ambient conditions to produce a superior CsPbBr 3 -CsPb 2 Br 5 composite film with a larger grain size and minimal defects. The achievement was attributed to the surface dissolution and recrystallization of the existing SCN - and EA. More specifically, the SCN - ions were first absorbed on the Pb atoms, leading to the dissolution and stripping of Cs + and Br - ions from the CsPbBr 3 QDs. On the other hand, the EA solution enhances the diffusion dynamics of surface atoms and the surfactant species. It is found that a small amount of CsPb 2 Br 5 in the composite film gives the best surface passivation, while the Br-rich surface decreases Br vacancies (V Br ) for a prolonged carrier lifetime. As a result, the fabricated device gives a higher solar cell efficiency of 6.81% with an outstanding long-term stability.

ANALYSIS OF THE WATER-SPLITTING CAPABILITIES OF GALLIUM INDIUM PHOSPHIDE NITRIDE (GaInPN)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Head, J.; Turner, J.

2007-01-01

With increasing demand for oil, the fossil fuels used to power society’s vehicles and homes are becoming harder to obtain, creating pollution problems and posing hazard’s to people’s health. Hydrogen, a clean and effi cient energy carrier, is one alternative to fossil fuels. Certain semiconductors are able to harness the energy of solar photons and direct it into water electrolysis in a process known as photoelectrochemical water-splitting. P-type gallium indium phosphide (p-GaInP2) in tandem with GaAs is a semiconductor system that exhibits water-splitting capabilities with a solar-tohydrogen effi ciency of 12.4%. Although this material is effi cient at producing hydrogenmore » through photoelectrolysis it has been shown to be unstable in solution. By introducing nitrogen into this material, there is great potential for enhanced stability. In this study, gallium indium phosphide nitride Ga1-yInyP1-xNx samples were grown using metal-organic chemical vapor deposition in an atmospheric-pressure vertical reactor. Photocurrent spectroscopy determined these materials to have a direct band gap around 2.0eV. Mott-Schottky analysis indicated p-type behavior with variation in fl atband potentials with varied frequencies and pH’s of solutions. Photocurrent onset and illuminated open circuit potential measurements correlated to fl atband potentials determined from previous studies. Durability analysis suggested improved stability over the GaInP2 system.« less

Solution-proceed Air-stable Copper Bismuth Iodide CuBiI₄ for Photovoltaics.

PubMed

Hu, Zhaosheng; Wang, Zhen; Kapil, Gaurav; Ma, Tingli; Iikubo, Satoshi; Minemoto, Takashi; Yoshino, Kenji; Toyoda, Taro; Shen, Qing; Hayase, Shuzi

2018-06-19

Bismuth based solar cells have been under intensive interest as an efficient non-toxic absorber in photovoltaics. Within this new family of semiconductors, we herein, report a new, long-term stable material copper bismuth iodide (CuBiI₄). A solution-processed method is provided under air atmosphere. The adopted HI assisted Dimethylacetamide (DMA) co-solvent can completely dissolve CuI and BiI₃ powders with high concentration compared to other organic solvent. Moreover, high vapor pressure of Tributyl phosphate, we select for the solvent vapor annealing (SVA), enables the whole low-temperature (≤70⁰C) film preparation. It results in a stable, uniform dense CuBiI₄ film. The average grains size increasing with precursor concentration, greatly enlarge the PL life time and hall mobility. And carrier lifetime of 3.03 ns as well as an appreciable hall mobility of 110 cm²/Vs were obtained. X-ray diffraction illustrates that the crystal structure is cubic (space group Fd3m) and favored in [1, 1, 1] direction. Moreover, the photovoltaic performance of CuBiI₄ was also investigated. A wide-bandgap (2.67 eV) solar cell with 0.82 % performance is presented, which shows an excellent long-term stability at least over 1008 hours under ambient conditions. This air-stable material may give an application in future tandem solar cells as a stable short-wavelength light absorber. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultra-Thin, Triple-Bandgap GaInP/GaAs/GaInAs Monolithic Tandem Solar Cells

NASA Technical Reports Server (NTRS)

Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, Sarah; Moriarty, T.;

Taking Steps toward PK-3 Success

ERIC Educational Resources Information Center

Eubanks, Shyrelle

2007-01-01

This tandem brief examines state policies and practices regarding critical PK-3 working conditions and identifies strategies to influence teacher job quality through collective bargaining and other collaborative processes. The document is designed to support efforts to change or implement policies that will improve the teaching and learning…

Characterization of Protein Flexibility Using Small-Angle X-Ray Scattering and Amplified Collective Motion Simulations

PubMed Central

Wen, Bin; Peng, Junhui; Zuo, Xiaobing; Gong, Qingguo; Zhang, Zhiyong

2014-01-01

Large-scale flexibility within a multidomain protein often plays an important role in its biological function. Despite its inherent low resolution, small-angle x-ray scattering (SAXS) is well suited to investigate protein flexibility and determine, with the help of computational modeling, what kinds of protein conformations would coexist in solution. In this article, we develop a tool that combines SAXS data with a previously developed sampling technique called amplified collective motions (ACM) to elucidate structures of highly dynamic multidomain proteins in solution. We demonstrate the use of this tool in two proteins, bacteriophage T4 lysozyme and tandem WW domains of the formin-binding protein 21. The ACM simulations can sample the conformational space of proteins much more extensively than standard molecular dynamics (MD) simulations. Therefore, conformations generated by ACM are significantly better at reproducing the SAXS data than are those from MD simulations. PMID:25140431

Optimization of three- and four-component reactions for polysubstituted piperidines: application to the synthesis and preliminary biological screening of a prototype library.

PubMed

Ulaczyk-Lesanko, Agnieszka; Pelletier, Eric; Lee, Maria; Prinz, Heino; Waldmann, Herbert; Hall, Dennis G

2007-01-01

Several solid- and solution-phase strategies were evaluated for the preparation of libraries of polysubstituted piperidines of type 7 using the tandem aza[4+2]cycloaddition/allylboration multicomponent reaction between 1-aza-4-boronobutadienes, maleimides, and aldehydes. A novel four-component variant of this chemistry was developed in solution phase, and it circumvents the need for pre-forming the azabutadiene component. A parallel synthesis coupled with compound purification by HPLC with mass-based fraction collection allowed the preparation of a library of 944 polysubstituted piperidines in a high degree of purity suitable for biological screening. A representative subset of 244 compounds was screened against a panel of phosphatase enzymes, and despite the modest levels of activity obtained, this study demonstrated that piperidines of type 7 display the right physical properties (e.g., solubility) to be assayed effectively in high-throughput enzymatic tests.

[Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Wenhua; Huang, Chaoqun; Xie, Wen; Shen, Li

2014-06-01

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 microm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 degrees C for 30 min. The compound was separated on a C18 column (100 mm x 2.1 mm, 3.5 microm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N > 10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil.

Validated Method for the Quantification of Baclofen in Human Plasma Using Solid-Phase Extraction and Liquid Chromatography–Tandem Mass Spectrometry

PubMed Central

Nahar, Limon Khatun; Cordero, Rosa Elena; Nutt, David; Lingford-Hughes, Anne; Turton, Samuel; Durant, Claire; Wilson, Sue; Paterson, Sue

2016-01-01

Abstract A highly sensitive and fully validated method was developed for the quantification of baclofen in human plasma. After adjusting the pH of the plasma samples using a phosphate buffer solution (pH 4), baclofen was purified using mixed mode (C8/cation exchange) solid-phase extraction (SPE) cartridges. Endogenous water-soluble compounds and lipids were removed from the cartridges before the samples were eluted and concentrated. The samples were analyzed using triple-quadrupole liquid chromatography–tandem mass spectrometry (LC–MS-MS) with triggered dynamic multiple reaction monitoring mode for simultaneous quantification and confirmation. The assay was linear from 25 to 1,000 ng/mL (r2 > 0.999; n = 6). Intraday (n = 6) and interday (n = 15) imprecisions (% relative standard deviation) were <5%, and the average recovery was 30%. The limit of detection of the method was 5 ng/mL, and the limit of quantification was 25 ng/mL. Plasma samples from healthy male volunteers (n = 9, median age: 22) given two single oral doses of baclofen (10 and 60 mg) on nonconsecutive days were analyzed to demonstrate method applicability. PMID:26538544

Direct evidence for tautomerization of the uracil moiety within the Pb2+/uridine-5'-monophosphate complex: a combined tandem mass spectrometry and IRMPD study.

PubMed

Salpin, Jean-Yves; Guillaumont, Sébastien; Ortiz, Daniel; Tortajada, Jeanine; Maître, Philippe

2011-08-15

The structure of the [Pb(UMP)-H](+) (UMP = uridine-5'-monophosphate) complex was studied in the gas phase by combining electrospray ionization (ESI), tandem mass spectrometry, and mid-infrared multiple photon dissociation (IRMPD) spectroscopy. The results obtained show that Pb(2+) ions interact not only with the deprotonated phosphate group but also with a carbonyl group of the nucleobase moiety by folding of the mononucleotide, resulting in macrochelates that are not likely to be present in solution. Comparison between the IRMPD and DFT-computed spectra suggests that the ESI-generated complex likely corresponds to a mixture of several structures, and establishes the enolic tautomers as the most abundant species for the [Pb(UMP)-H](+) ion, while the very weak IRMPD signal observed at ∼1763 cm(-1) points to a minor population of oxo forms. Our data also suggest that losing the nucleobase residue under CID conditions does not necessarily mean a lack of interaction between the metal and the nucleobase moiety, as commonly reported in the literature for large oligonucleotides. © 2011 American Chemical Society

Improved sample preparation to determine acrylamide in difficult matrixes such as chocolate powder, cocoa, and coffee by liquid chromatography tandem mass spectroscopy.

PubMed

Delatour, Thierry; Périsset, Adrienne; Goldmann, Till; Riediker, Sonja; Stadler, Richard H

2004-07-28

An improved sample preparation (extraction and cleanup) is presented that enables the quantification of low levels of acrylamide in difficult matrixes, including soluble chocolate powder, cocoa, coffee, and coffee surrogate. Final analysis is done by isotope-dilution liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) using d3-acrylamide as internal standard. Sample pretreatment essentially encompasses (a) protein precipitation with Carrez I and II solutions, (b) extraction of the analyte into ethyl acetate, and (c) solid-phase extraction on a Multimode cartridge. The stability of acrylamide in final extracts and in certain commercial foods and beverages is also reported. This approach provided good performance in terms of linearity, accuracy and precision. Full validation was conducted in soluble chocolate powder, achieving a decision limit (CCalpha) and detection capability (CCbeta) of 9.2 and 12.5 microg/kg, respectively. The method was extended to the analysis of acrylamide in various foodstuffs such as mashed potatoes, crisp bread, and butter biscuit and cookies. Furthermore, the accuracy of the method is demonstrated by the results obtained in three inter-laboratory proficiency tests. Copyright 2004 American Chemical Society

CFD-CAA Coupled Calculations of a Tandem Cylinder Configuration to Assess Facility Installation Effects

NASA Technical Reports Server (NTRS)

Redonnet, Stephane; Lockard, David P.; Khorrami, Mehdi R.; Choudhari, Meelan M.

2011-01-01

This paper presents a numerical assessment of acoustic installation effects in the tandem cylinder (TC) experiments conducted in the NASA Langley Quiet Flow Facility (QFF), an open-jet, anechoic wind tunnel. Calculations that couple the Computational Fluid Dynamics (CFD) and Computational Aeroacoustics (CAA) of the TC configuration within the QFF are conducted using the CFD simulation results previously obtained at NASA LaRC. The coupled simulations enable the assessment of installation effects associated with several specific features in the QFF facility that may have impacted the measured acoustic signature during the experiment. The CFD-CAA coupling is based on CFD data along a suitably chosen surface, and employs a technique that was recently improved to account for installed configurations involving acoustic backscatter into the CFD domain. First, a CFD-CAA calculation is conducted for an isolated TC configuration to assess the coupling approach, as well as to generate a reference solution for subsequent assessments of QFF installation effects. Direct comparisons between the CFD-CAA calculations associated with the various installed configurations allow the assessment of the effects of each component (nozzle, collector, etc.) or feature (confined vs. free jet flow, etc.) characterizing the NASA LaRC QFF facility.

Determination of ketamine and its main metabolites by liquid chromatography coupled to tandem mass spectrometry in pig plasma: Comparison of extraction methods.

PubMed

Ramiole, Cindy; D'Hayer, Benoit; Boudy, Vincent; Legagneux, Josette; Fonsart, Julien; Houzé, Pascal

2017-11-30

A rapid, sensitive and specific liquid chromatography coupled to tandem mass spectrometry method was developed for the simultaneous quantification pig plasma of ketamine and its two principal metabolites, norketamine and dehydronorketamine. Three extraction procoles were assessed including acetonitrile precipitation, Oase™ microplate extraction, and liquid-liquid extraction. Oase™ microplate extraction induced no significant matrix effect, important signal/noise ratio and good recoveries, ranging from 82 to 87% for the considered compounds. Using this extraction procedure, the assay was linear in the dynamic range 10-3000ng/mL (R 2 >0.99) regardless of the analytes. Intra- and inter-day accuracies were less than 12% for all compounds and intra- and inter-day precisions expressed as RSD were within <9.9%. Samples were stable in different storage conditions. High ketamine, norketamine and dehydronorketamine concentrations up to 15,000ng/mL can be determined with good precision using appropriate sample dilution. The assay was successfully applied to pig plasma samples to determine the pharmacokinetics of ketamine and the consecutive metabolites after buccal administration of a 4mg/kg ketamine base solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

Annotation: a computational solution for streamlining metabolomics analysis

PubMed Central

Domingo-Almenara, Xavier; Montenegro-Burke, J. Rafael; Benton, H. Paul; Siuzdak, Gary

2017-01-01

Metabolite identification is still considered an imposing bottleneck in liquid chromatography mass spectrometry (LC/MS) untargeted metabolomics. The identification workflow usually begins with detecting relevant LC/MS peaks via peak-picking algorithms and retrieving putative identities based on accurate mass searching. However, accurate mass search alone provides poor evidence for metabolite identification. For this reason, computational annotation is used to reveal the underlying metabolites monoisotopic masses, improving putative identification in addition to confirmation with tandem mass spectrometry. This review examines LC/MS data from a computational and analytical perspective, focusing on the occurrence of neutral losses and in-source fragments, to understand the challenges in computational annotation methodologies. Herein, we examine the state-of-the-art strategies for computational annotation including: (i) peak grouping or full scan (MS1) pseudo-spectra extraction, i.e., clustering all mass spectral signals stemming from each metabolite; (ii) annotation using ion adduction and mass distance among ion peaks; (iii) incorporation of biological knowledge such as biotransformations or pathways; (iv) tandem MS data; and (v) metabolite retention time calibration, usually achieved by prediction from molecular descriptors. Advantages and pitfalls of each of these strategies are discussed, as well as expected future trends in computational annotation. PMID:29039932

Effect of non-stoichiometric solution chemistry on improving the performance of wide-bandgap perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Mengjin; Kim, Dong Hoe; Yu, Yue

A high-efficiency wide-bandgap (WBG) perovskite solar cell is critical for developing perovskite-related (e.g., all-perovskite, perovskite/Si, or perovskite/Cu(In,Ga)Se 2) tandem devices. Here, we demonstrate the use of non-stoichiometric precursor chemistry with excess methylammonium halides (MAX; X = I, Br, or Cl) for preparing high-quality ~1.75-eV FA 0.83Cs 0.17Pb(I 0.6Br 0.4) 3 perovskite solar cells. Among various methylammonium halides, using excess MABr in the non-stoichiometric precursor exhibits the strongest effect on improving perovskite crystallographic properties and device characteristics without affecting the perovskite composition. In contrast, using excess MAI significantly reduces the bandgap of perovskite due to the replacement of Br with I.more » Using 40% excess MABr, we demonstrate a single-junction WBG perovskite solar cell with stabilized efficiency of 16.4%. We further demonstrate a 20.3%-efficient 4-terminal tandem device by using a 14.7%-efficient semi-transparent WBG perovskite top cell and an 18.6%-efficient unfiltered (5.6%-efficient filtered) Si bottom cell.« less

Comprehensive determination of flavouring additives and nicotine in e-cigarette refill solutions. Part I: Liquid chromatography-tandem mass spectrometry analysis.

PubMed

Aszyk, Justyna; Kubica, Paweł; Kot-Wasik, Agata; Namieśnik, Jacek; Wasik, Andrzej

2017-10-13

Liquid chromatography-tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS) methods were developed for the simultaneous determination of 42 flavouring compounds and nicotine in liquids for e-cigarettes. The chromatographic separation was performed using an Ace ® Ultracore™ SuperC18™ (100×2.1mm, 2.5μm) column in both acidic and alkaline pH conditions to separate all the compounds. A simple "dilute & shoot" approach was used for the sample preparation. The method validation was performed by evaluating key analytical parameters such as linearity, accuracy, selectivity, precision, limit of detection (LOD) and limit of quantification (LOQ). The calibration curves showed good linearity within the specific ranges for the investigated compounds with correlation coefficients greater than 0.990 in each case. The recovery for all the investigated compounds varied from 89% to 110%. The intra- and inter-day precision were within the acceptable limits (±15%) at all tested concentrations. The applicability of the methods was examined by analysing 25 liquid samples from e-cigarettes commercially available on the Polish market. Copyright © 2017 Elsevier B.V. All rights reserved.

Validation and Application of an Ultra High-Performance Liquid Chromatography Tandem Mass Spectrometry Method for Yuanhuacine Determination in Rat Plasma after Pulmonary Administration: Pharmacokinetic Evaluation of a New Drug Delivery System.

PubMed

Li, Man; Liu, Xiao; Cai, Hao; Shen, Zhichun; Xu, Liu; Li, Weidong; Wu, Li; Duan, Jinao; Chen, Zhipeng

2016-12-16

Yuanhuacine was found to have significant inhibitory activity against A-549 human lung cancer cells. However, there would be serious adverse toxicity effects after systemic administration of yuanhuacine, such as by oral and intravenous ways. In order to achieve better curative effect and to alleviate the adverse toxicity effects, we tried to deliver yuanhuacine directly into the lungs. Ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was used to detect the analyte and IS. After extraction (ether:dichloromethane = 8:1), the analyte and IS were separated on a Waters BEH-C 18 column (100 mm × 2.1 mm, 1.7 μm) under a 5 min gradient elution using a mixture of acetonitrile and 0.1% formic acid aqueous solution as mobile phase at a flow rate of 0.3 mL/min. ESI positive mode was chosen for detection. The method was fully validated for its selectivity, accuracy, precision, stability, matrix effect, and extraction recovery. This new method for yuanhuacine concentration determination in rat plasma was reliable and could be applied for its preclinical and clinical monitoring purpose.

Effect of non-stoichiometric solution chemistry on improving the performance of wide-bandgap perovskite solar cells

DOE PAGES

Yang, Mengjin; Kim, Dong Hoe; Yu, Yue; ...

2017-10-02

A high-efficiency wide-bandgap (WBG) perovskite solar cell is critical for developing perovskite-related (e.g., all-perovskite, perovskite/Si, or perovskite/Cu(In,Ga)Se 2) tandem devices. Here, we demonstrate the use of non-stoichiometric precursor chemistry with excess methylammonium halides (MAX; X = I, Br, or Cl) for preparing high-quality ~1.75-eV FA 0.83Cs 0.17Pb(I 0.6Br 0.4) 3 perovskite solar cells. Among various methylammonium halides, using excess MABr in the non-stoichiometric precursor exhibits the strongest effect on improving perovskite crystallographic properties and device characteristics without affecting the perovskite composition. In contrast, using excess MAI significantly reduces the bandgap of perovskite due to the replacement of Br with I.more » Using 40% excess MABr, we demonstrate a single-junction WBG perovskite solar cell with stabilized efficiency of 16.4%. We further demonstrate a 20.3%-efficient 4-terminal tandem device by using a 14.7%-efficient semi-transparent WBG perovskite top cell and an 18.6%-efficient unfiltered (5.6%-efficient filtered) Si bottom cell.« less

Determination of phthalate esters in cleaning and personal care products by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

PubMed

Viñas, Pilar; Campillo, Natalia; Pastor-Belda, Marta; Oller, Ainhoa; Hernández-Córdoba, Manuel

2015-01-09

Phthalic acid esters (PEs) were preconcentrated from cleaning products, detergents and cosmetics using ultrasound assisted extraction (UAE) in the presence of acetonitrile, and then submitted to dispersive liquid-liquid microextraction (DLLME). For DLLME, 3mL of acetonitrile extract, 150μL carbon tetrachloride and 10mL aqueous solution were used. The enriched organic phase was evaporated, reconstituted with 25μL acetonitrile and injected into a liquid chromatograph with a mobile phase (acetonitrile:10mM ammonium acetate, pH 4) under gradient elution. Detection was carried out using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the multiple reaction monitoring mode (MRM) of the positive fragment ions. Quantification was carried out using matrix-matched standards. Detection limits were in the range 0.04-0.45ngmL(-1) for the six PEs considered. The recoveries obtained were in the 84-124% range, with RSDs lower than 10%. Thirty three different cleaning products were analyzed. The most frequently found compound was diethyl phthalate. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantification of endocrine disruptors and pesticides in water by gas chromatography-tandem mass spectrometry. Method validation using weighted linear regression schemes.

PubMed

Mansilha, C; Melo, A; Rebelo, H; Ferreira, I M P L V O; Pinho, O; Domingues, V; Pinho, C; Gameiro, P

2010-10-22

A multi-residue methodology based on a solid phase extraction followed by gas chromatography-tandem mass spectrometry was developed for trace analysis of 32 compounds in water matrices, including estrogens and several pesticides from different chemical families, some of them with endocrine disrupting properties. Matrix standard calibration solutions were prepared by adding known amounts of the analytes to a residue-free sample to compensate matrix-induced chromatographic response enhancement observed for certain pesticides. Validation was done mainly according to the International Conference on Harmonisation recommendations, as well as some European and American validation guidelines with specifications for pesticides analysis and/or GC-MS methodology. As the assumption of homoscedasticity was not met for analytical data, weighted least squares linear regression procedure was applied as a simple and effective way to counteract the greater influence of the greater concentrations on the fitted regression line, improving accuracy at the lower end of the calibration curve. The method was considered validated for 31 compounds after consistent evaluation of the key analytical parameters: specificity, linearity, limit of detection and quantification, range, precision, accuracy, extraction efficiency, stability and robustness. Copyright © 2010 Elsevier B.V. All rights reserved.

Electrolytes Based on TEMPO–Co Tandem Redox Systems Outperform Single Redox Systems in Dye‐sensitized Solar Cells

PubMed Central

Cong, Jiayan; Hao, Yan; Boschloo, Gerrit

2014-01-01

Abstract A new TEMPO–Co tandem redox system with TEMPO and Co(bpy)3 2+/3+ has been investigated for the use in dye‐sensitized solar cells (DSSCs). A large open‐circuit voltage (V OC) increase, from 862 mV to 965 mV, was observed in the tandem redox system, while the short‐circuit current density (J SC) was maintained. The conversion efficiency was observed to increase from 7.1 % for cells containing the single Co(bpy)3 2+/3+ redox couple, to 8.4 % for cells containing the TEMPO–Co tandem redox system. The reason for the increase in V OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem redox system, the faster recombination problem of the single TEMPO redox couple is resolved and the mass‐transport of the metal‐complex‐based electrolyte is also improved. This TEMPO–Co tandem system is so far the most effienct tandem redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single redox systems in electrolytes for DSSCs. PMID:25504818

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

ERIC Educational Resources Information Center

Cziko, Gary A.

2004-01-01

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…

Targeted tandem duplication of a large chromosomal segment in Aspergillus oryzae.

PubMed

Takahashi, Tadashi; Sato, Atsushi; Ogawa, Masahiro; Hanya, Yoshiki; Oguma, Tetsuya

2014-08-01

We describe here the first successful construction of a targeted tandem duplication of a large chromosomal segment in Aspergillus oryzae. The targeted tandem chromosomal duplication was achieved by using strains that had a 5'-deleted pyrG upstream of the region targeted for tandem chromosomal duplication and a 3'-deleted pyrG downstream of the target region. Consequently,strains bearing a 210-kb targeted tandem chromosomal duplication near the centromeric region of chromosome 8 and strains bearing a targeted tandem chromosomal duplication of a 700-kb region of chromosome 2 were successfully constructed. The strains bearing the tandem chromosomal duplication were efficiently obtained from the regenerated protoplast of the parental strains. However, the generation of the chromosomal duplication did not depend on the introduction of double-stranded breaks(DSBs) by I-SceI. The chromosomal duplications of these strains were stably maintained after five generations of culture under nonselective conditions. The strains bearing the tandem chromosomal duplication in the 700-kb region of chromosome 2 showed highly increased protease activity in solid-state culture, indicating that the duplication of large chromosomal segments could be a useful new breeding technology and gene analysis method.

Modeling the Performance Limitations and Prospects of Perovskite/Si Tandem Solar Cells under Realistic Operating Conditions

PubMed Central

2017-01-01

Perovskite/Si tandem solar cells have the potential to considerably out-perform conventional solar cells. Under standard test conditions, perovskite/Si tandem solar cells already outperform the Si single junction. Under realistic conditions, however, as we show, tandem solar cells made from current record cells are hardly more efficient than the Si cell alone. We model the performance of realistic perovskite/Si tandem solar cells under real-world climate conditions, by incorporating parasitic cell resistances, nonradiative recombination, and optical losses into the detailed-balance limit. We show quantitatively that when optimizing these parameters in the perovskite top cell, perovskite/Si tandem solar cells could reach efficiencies above 38% under realistic conditions, even while leaving the Si cell untouched. Despite the rapid efficiency increase of perovskite solar cells, our results emphasize the need for further material development, careful device design, and light management strategies, all necessary for highly efficient perovskite/Si tandem solar cells. PMID:28920081

Modeling the Performance Limitations and Prospects of Perovskite/Si Tandem Solar Cells under Realistic Operating Conditions.

PubMed

Futscher, Moritz H; Ehrler, Bruno

2017-09-08

Perovskite/Si tandem solar cells have the potential to considerably out-perform conventional solar cells. Under standard test conditions, perovskite/Si tandem solar cells already outperform the Si single junction. Under realistic conditions, however, as we show, tandem solar cells made from current record cells are hardly more efficient than the Si cell alone. We model the performance of realistic perovskite/Si tandem solar cells under real-world climate conditions, by incorporating parasitic cell resistances, nonradiative recombination, and optical losses into the detailed-balance limit. We show quantitatively that when optimizing these parameters in the perovskite top cell, perovskite/Si tandem solar cells could reach efficiencies above 38% under realistic conditions, even while leaving the Si cell untouched. Despite the rapid efficiency increase of perovskite solar cells, our results emphasize the need for further material development, careful device design, and light management strategies, all necessary for highly efficient perovskite/Si tandem solar cells.

Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma.

PubMed

Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine; Halvorsen, Trine Grønhaug; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid

2016-09-10

Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation of phosphatidylcholines (PC), sphingomyelins (SM), and lysophosphatidylcholines (Lyso-PC). In both generic methods, no phospholipids were detected in the acceptor solutions. Thus, PALME appeared to be highly efficient for phospholipid removal. To further support this, qualitative (post-column infusion) and quantitative matrix effects were investigated with fluoxetine, fluvoxamine, and quetiapine as model analytes. No signs of matrix effects were observed. Finally, PALME was evaluated for the aforementioned drug substances, and data were in accordance with European Medicines Agency (EMA) guidelines. Copyright © 2016 Elsevier B.V. All rights reserved.

TRAP: automated classification, quantification and annotation of tandemly repeated sequences.

PubMed

Sobreira, Tiago José P; Durham, Alan M; Gruber, Arthur

2006-02-01

TRAP, the Tandem Repeats Analysis Program, is a Perl program that provides a unified set of analyses for the selection, classification, quantification and automated annotation of tandemly repeated sequences. TRAP uses the results of the Tandem Repeats Finder program to perform a global analysis of the satellite content of DNA sequences, permitting researchers to easily assess the tandem repeat content for both individual sequences and whole genomes. The results can be generated in convenient formats such as HTML and comma-separated values. TRAP can also be used to automatically generate annotation data in the format of feature table and GFF files.

On the importance of a funneled energy landscape for the assembly and regulation of multidomain Src tyrosine kinases.

PubMed

Faraldo-Gómez, José D; Roux, Benoît

2007-08-21

Regulation of signaling pathways in the cell often involves multidomain allosteric enzymes that are able to adopt alternate active or inactive conformations in response to specific stimuli. It is therefore of great interest to elucidate the energetic and structural determinants that govern the conformational plasticity of these proteins. In this study, free-energy computations have been used to address this fundamental question, focusing on one important family of signaling enzymes, the Src tyrosine kinases. Inactivation of these enzymes depends on the formation of an assembly comprising a tandem of SH3 and SH2 modules alongside a catalytic domain. Activation results from the release of the SH3 and SH2 domains, which are then believed to be structurally uncoupled by virtue of a flexible peptide link. In contrast to this view, this analysis shows that inactivation depends critically on the intrinsic propensity of the SH3-SH2 tandem to adopt conformations that are conducive to the assembled inactive state, even when no interactions with the rest of the kinase are possible. This funneling of the available conformational space is encoded within the SH3-SH2 connector, which appears to have evolved to modulate the flexibility of the tandem in solution. To further substantiate this notion, we show how constitutively activating mutations in the SH3-SH2 connector shift the assembly equilibrium toward the disassembled, active state. Based on a similar analysis of several constructs of the kinase complex, we propose that assembly is characterized by the progressive optimization of the protein's conformational energy, with little or no energetic frustration.

Identification of ubiquitin/ubiquitin-like protein modification from tandem mass spectra with various PTMs

PubMed Central

2011-01-01

Background Various solutions have been introduced for the identification of post-translational modification (PTM) from tandem mass spectrometry (MS/MS) in proteomics field but the identification of peptide modifiers, such as Ubiquitin (Ub) and ubiquitin-like proteins (Ubls), is still a challenge. The fragmentation of peptide modifier produce complex shifted ion mass patterns in combination with other PTMs, which makes it difficult to identify and locate the PTMs on a protein sequence. Currently, most PTM identification methods do not consider the complex fragmentation of peptide modifier or deals it separately from the other PTMs. Results We developed an advanced PTM identification method that inspects possible ion patterns of the most known peptide modifiers as well as other known biological and chemical PTMs to make more comprehensive and accurate conclusion. The proposed method searches all detectable mass differences of measured peaks from their theoretical values and the mass differences within mass tolerance range are grouped as mass shift classes. The most possible locations of multiple PTMs including peptide modifiers can be determined by evaluating all possible scenarios generated by the combination of the qualified mass shift classes.The proposed method showed excellent performance in the test with simulated spectra having various PTMs including peptide modifiers and in the comparison with recently developed methods such as QuickMod and SUMmOn. In the analysis of HUPO Brain Proteome Project (BPP) datasets, the proposed method could find the ubiquitin modification sites that were not identified by other conventional methods. Conclusions This work presents a novel method for identifying bothpeptide modifiers that generate complex fragmentation patternsand PTMs that are not fragmented during fragmentation processfrom tandem mass spectra. PMID:22373085

Development of a new multi-residue laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry method for the detection and quantification of pesticides and pharmaceuticals in wastewater samples.

PubMed

Boisvert, Michel; Fayad, Paul B; Sauvé, Sébastien

2012-11-19

A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17β-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122ng L(-1) while the limit of quantification ranged from 90 to 370ng L(-1). Calibration curves in the wastewater matrix showed good linearity (R(2)≥0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparative evaluation of two dose optimization methods for image-guided, highly-conformal, tandem and ovoids cervix brachytherapy planning

NASA Astrophysics Data System (ADS)

Ren, Jiyun; Menon, Geetha; Sloboda, Ron

2013-04-01

Although the Manchester system is still extensively used to prescribe dose in brachytherapy (BT) for locally advanced cervix cancer, many radiation oncology centers are transitioning to 3D image-guided BT, owing to the excellent anatomy definition offered by modern imaging modalities. As automatic dose optimization is highly desirable for 3D image-based BT, this study comparatively evaluates the performance of two optimization methods used in BT treatment planning—Nelder-Mead simplex (NMS) and simulated annealing (SA)—for a cervix BT computer simulation model incorporating a Manchester-style applicator. Eight model cases were constructed based on anatomical structure data (for high risk-clinical target volume (HR-CTV), bladder, rectum and sigmoid) obtained from measurements on fused MR-CT images for BT patients. D90 and V100 for HR-CTV, D2cc for organs at risk (OARs), dose to point A, conformation index and the sum of dwell times within the tandem and ovoids were calculated for optimized treatment plans designed to treat the HR-CTV in a highly conformal manner. Compared to the NMS algorithm, SA was found to be superior as it could perform optimization starting from a range of initial dwell times, while the performance of NMS was strongly dependent on their initial choice. SA-optimized plans also exhibited lower D2cc to OARs, especially the bladder and sigmoid, and reduced tandem dwell times. For cases with smaller HR-CTV having good separation from adjoining OARs, multiple SA-optimized solutions were found which differed markedly from each other and were associated with different choices for initial dwell times. Finally and importantly, the SA method yielded plans with lower dwell time variability compared with the NMS method.

Multi-residue method for the determination of 450 pesticide residues in honey, fruit juice and wine by double-cartridge solid-phase extraction/gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

PubMed

Pang, G-F; Fan, C-L; Liu, Y-M; Cao, Y-Z; Zhang, J-J; Fu, B-L; Li, X-M; Li, Z-Y; Wu, Y-P

2006-08-01

A multi-residue method was developed for the determination of 450 pesticide residues in honey, fruit juice and wine using double-cartridge solid-phase extraction (SPE), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method development was based on an appraisal of the characteristics of GC-MS and LC-MS-MS for 654 pesticides as well as the efficiency of extraction and purification from honey, fruit juice and wine. Samples were first diluted with water plus acetone, then extracted with portions of dichloromethane. The extracts were concentrated and cleaned up with graphitized carbon black and aminopropyl cartridges stacked in tandem. Pesticides were eluted with acetonitrile + toluene, and the eluates were concentrated. For 383 pesticides, the eluate was extracted with hexane twice and internal standard solution was added prior to GC-MS determination. For 67 pesticides, extraction was with methanol prior to LC-MS-MS determination. The limit of detection for the method was between 1.0 and 300 ng g(-1) depending on each pesticide analyte. At the three fortification levels of 2.0-3000 ng g(-1), the average recovery rates were between 59 and 123%, among which 413 pesticides (92% of the 450) had recovery rates of 70-120% and 35 pesticides (8% of the 450) had recovery rates of 59-70%. There were 437 pesticides (97% of the 450) with a relative standard deviation below 25%; there were 13 varieties (3% of the 450) between 25.0 and 30.4%.

Determination of artemisitene in rat plasma by ultra-performance liquid chromatography/tandem mass spectrometry and its application in pharmacokinetics.

PubMed

Wu, Li-Lan; Wu, Yun-Shan; Chen, Wei-Ying; Zhou, Wen; Tang, Lipeng; Li, Ben; Liu, Bo

2017-07-15

Artemisitene shows a wide variety of pharmacological activities, such as antioxidant protection in vitro and in vivo. It has been identified as a novel Nrf2 inducer. However, there is no report on an ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method to quantitate artemisitene in rat plasma and its application to a pharmacokinetic profile study. An ACQUITY UPLC™ BEH Symmetry Shield RP18 column (1.7 μm, 2.1 mm × 100 mm) was used at a flow rate of 0.3 mL·min -1 . Mass detection was performed by electrospray ionization tandem mass spectrometry via multiple reaction monitoring (MRM) in positive mode. Plasma samples were pre-treated by a single-step extraction with 0.1% formic acid aqueous solutions-acetonitrile, and tolbutamide was used as internal standard. The calibration curve was from 0.98 to 1000 ng∙mL -1 (r 2  = 0.995). The extraction recoveries were 61.5-79.4% and 81.7-94.6% for artemisitene and tolbutamide, respectively. The lower limit of quantification (LLOQ) was 0.98 ng∙mL -1 . The absolute bioavailability of artemisitene was 3.7% after intravenous and oral administration in rats. The UPLC/MS/MS assay was validated for linearity, accuracy, stability, extraction recovery, matrix effects, and intra-day and inter-day precision. The method, for the first time, achieved some pharmacokinetic parameters and was successfully applied to a pharmacokinetic study Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Wetland Mapping with Quad-Pol Data Acquired during Tandem-X Science Phase

NASA Astrophysics Data System (ADS)

Mleczko, M.; Mroz, M.; Fitrzyk, M.

2016-06-01

The aim of this study was to exploit fully polarimetric SAR data acquired during TanDEM-X - Science Phase (2014/2015) over herbaceous wetlands of the Biebrza National Park (BbNP) in North-Eastern Poland for mapping seasonally flooded grasslands and permanent natural vegetation associations. The main goal of this work was to estimate the advantage of fully polarimetric radar images (QuadPol) versus alternative polarization (AltPol) modes. The methodology consisted in processing of several data subsets through polarimetric decompositions of complex quad-pol datasets, classification of multitemporal backscattering images, complementing backscattering images with Shannon Entropy, exploitation of interferometric coherence from tandem operations. In each case the multidimensional stack of images has been classified using ISODATA unsupervised clustering algorithm. With 6 QUAD-POL TSX/TDX acquisitions it was possible to distinguish correctly 5 thematic classes related to their water regime: permanent water bodies, temporarily flooded areas, wet grasslands, dry grasslands and common reed. This last category was possible to distinguish from deciduous forest only with Yamaguchi 4 component decomposition. The interferometric coherence calculated for tandem pairs turned out not so efficient as expected for this wetland mapping.

Analysis of lignans in Magnoliae Flos by turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry.

PubMed

Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2016-04-01

In this study, a method coupling turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry was developed for analyzing the lignans in Magnoliae Flos. By the online pretreatment of turbulent flow chromatography solid-phase extraction, the impurities removal and analytes concentration were automatically processed, and the lignans were separated rapidly and well. Seven lignans of Magnoliae Flos including epieudesmin, magnolin, 1-irioresinol-B-dimethyl ether, epi-magnolin, fargesin aschantin, and demethoxyaschantin were identified by comparing their retention behavior, UV spectra, and mass spectra with those of reference substances or literature data. The developed method was validated, and the good results showed that the method was not only automatic and rapid, but also accurate and reliable. The turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry method holds a high potential to become an effective method for the quality control of lignans in Magnoliae Flos and a useful tool for the analysis of other complex mixtures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Short Tandem Repeat DNA Internet Database

National Institute of Standards and Technology Data Gateway

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

Rapid and simultaneous analysis of ten aromatic amines in mainstream cigarette smoke by liquid chromatography/electrospray ionization tandem mass spectrometry under ISO and "Health Canada intensive" machine smoking regimens.

PubMed

Xie, Fuwei; Yu, Jingjing; Wang, Sheng; Zhao, Ge; Xia, Qiaoling; Zhang, Xiaobing; Zhang, Shusheng

2013-10-15

Ten primary aromatic amines (AAs) in mainstream cigarette smoke under both ISO and "Health Canada intensive" machine smoking regimens were determined in this work, which were suspected to be carcinogenic compounds. The measured AAs included aniline, ortho-toluidine, meta-toluidine, para-toluidine, 1-naphthylamine, 2-naphthylamine, 3-aminobiphenyl, 4-aminobiphenyl, meta-phenylenediamine and meta-anisidine. For rapidly and sensitively analyzing these AAs, a liquid chromatography-electrospray ionization tandem mass spectrometric (LC-MS/MS) method coupled with solid phase extraction (SPE) was developed. The particulate phase of mainstream cigarette smoke was collected on a Cambridge filter pads, while the gas phase was trapped by 25 mL 5% HCl solution. Then, the pad was extracted in an ultrasonic bath with the impinger HCl solution. After being neutralized with NaOH, the extract was purified with a HLB solid phase extraction column, and then was analyzed with LC-MS/MS using isotope-labeled internal standard. The overall sample pretreatment and analysis time was less than 1.5h. The limits of detection for all targets ranged from 0.05 ng cig(-1) to 0.96 ng cig(-1) with the recoveries in the range of 75.0-131.8%. And the intra-day and inter-day precisions were less than 10% and 16%, respectively. Under HCI machine smoking regimen, the AAs yields in mainstream cigarette smoke were much higher and the average increases were greater than 100% compared with those under ISO smoking condition. Copyright © 2013 Elsevier B.V. All rights reserved.

[Simultaneous determination of nine estrogens in eel by ultrafast liquid chromatography-tandem mass spectrometry with isotope dilution technique and solid-phase extraction].

PubMed

Chen, Xiaohong; Yao, Shanshan; Li, Xiaoping; Zhao, Yonggang; Jin, Micong

2012-11-01

Developing a rapid and sensitive analytical method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) with solid-phase extraction (SPE) for the simultaneous determination of nine estrogens (dienestrol, diethylstilbestrol, estrone, hexestrol, 17-alpha-estradiol, 17-beta-estradiol, estriol, 17alpha-ethinylestradiol and estradiol valerate) in eel. After the sample was extracted by acetonitrile and cleaned by Waters Oasis HLB solid-phase extraction cartridge, the UFLC separation was performed on a Shim-pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) with a linear gradient elution program of methanol solution containing 0.04% ammonia (v/v) and 0.04% ammonia aqueous solution (v/v) as the mobile phase. Electrospray ionization was applied and operated in the negative multiple reaction monitoring (MRM) mode. The quantitation was used by isotope internal standard dilution technique. The results showed that the limits of quantitation (LOQs, S/N(10) were in the range of 0.07-0.4 microg/kg, the calibration curves were in good linearities for the nine analytes in the range of 0.5-50.0 microg/L with the correlative coefficients (r2) more than 0.998, the recoveries were between 81.0% and 110.0% with the relative standard deviations (RSDs) of 1.92%-8.24%. Additional, the mass spectra characterization of the nine estrogens was discussed and the fragmentation pathways were speculated. The developed method is rapid, sensitive, specific and reproducible, and adapts not only to the simultaneous determination of the nine trace estrogens including the epimer of 17-alpha-estradiol and 17-beta-estradiol but also to the identified detection in other fish tissues.

Rapid determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction and ultraperformance convergence chromatography tandem mass spectrometry.

PubMed

Deng, Huimin; Yang, Fei; Li, Zhonghao; Bian, Zhaoyang; Fan, Ziyan; Wang, Ying; Liu, Shanshan; Tang, Gangling

2017-07-21

Aromatic amines in mainstream cigarette smoke have long been monitored due to their carcinogenic toxicity. In this work, a reliable and rapid method was developed for the simultaneous determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction (DLLME) and ultraperformance convergence chromatography tandem mass spectrometry (UPC 2 -MS/MS). Briefly, the particulate phase of the cigarette smoke was captured by a Cambridge filter pad, and diluted hydrogen chloride aqueous solution is employed to extract the aromatic amines under mechanical shaking. After alkalization with sodium hydroxide solution, small amount of toluene was introduced to further extract and enrich aromatic amines by modified DLLME under vortexing. After centrifugation, toluene phase was purified by a universal QuEChERS cleanup kit and was finally analyzed by UPC 2 -MS/MS. Attributing to the superior performance of UPC 2 -MS/MS, this novel approach allowed the separation and determination of 9 aromatic amines within 5.0min with satisfactory resolution and sensitivity. The proposed method was finally validated using Kentucky reference cigarette 3R4F, and emission levels of targeted aromatic amines determined were comparable to previously reported methods At three different spiked levels, the recoveries of most analytes were ranged from 74.01% to 120.50% with relative standard deviation (RSD) less than 12%, except that the recovery of p-toluidine at low spiked level and 3-aminobiphenyl at medium spiked level was 62.77% and 69.37% respectively. Thus, this work provides a novel alternative method for the simultaneous analysis of 9 aromatic amines in mainstream cigarette smoke. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel ultra high-performance liquid chromatography-tandem mass spectrometry method for the simultaneous determination of xanthones and steroidal saponins in crude and salt-processed Anemarrhenae Rhizoma aqueous extracts.

PubMed

Ji, De; Su, Xiaonan; Huang, Ziyan; Wang, Qiaohan; Lu, Tulin

2018-06-01

We established a rapid and sensitive ultra high-performance liquid chromatography tandem mass spectrometry method for the simultaneous quantification of xanthones and steroidal saponins in rat plasma. Chromatographic separation was achieved on a C 18 column with a mobile phase comprising acetonitrile and 0.1% formic acid. The detection was performed by negative electrospray ionization in multiple reaction monitoring mode. The validated method showed good linearity within the tested range (r > 0.9945). The intra- and interday precision at high, medium, and low concentrations was less than 7.96%. The bias of accuracies ranged from -1.92 to 9.62%. The extraction recoveries of the compounds ranged from 84.78 to 88.69%, and the matrix effects ranged from 96.76 to 108.59%. This method was successfully applied to a pharmacokinetic comparison of crude and salt-processed Anemarrhenae Rhizoma aqueous extracts after oral administration in rats. The maximum plasma concentration and area under concentration-time curve of timosaponin BIII and timosaponin AIII increased significantly (P < 0.05 or 0.01) and those of timosaponin BII decreased significantly (P < 0.05) after processing. These results could contribute to the clinical application of crude and salt-processed Anemarrhenae Rhizoma and reveal the processing mechanism. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-task and dual-task tandem gait test performance after concussion.

PubMed

Howell, David R; Osternig, Louis R; Chou, Li-Shan

2017-07-01

To compare single-task and dual-task tandem gait test performance between athletes after concussion with controls on observer-timed, spatio-temporal, and center-of-mass (COM) balance control measurements. Ten participants (19.0±5.5years) were prospectively identified and completed a tandem gait test protocol within 72h of concussion and again 1 week, 2 weeks, 1 month, and 2 months post-injury. Seven uninjured controls (20.0±4.5years) completed the same protocol in similar time increments. Tandem gait test trials were performed with (dual-task) and without (single-task) concurrently performing a cognitive test as whole-body motion analysis was performed. Outcome variables included test completion time, average tandem gait velocity, cadence, and whole-body COM frontal plane displacement. Concussion participants took significantly longer to complete the dual-task tandem gait test than controls throughout the first 2 weeks post-injury (mean time=16.4 [95% CI: 13.4-19.4] vs. 10.1 [95% CI: 6.4-13.7] seconds; p=0.03). Single-task tandem gait times were significantly lower 72h post-injury (p=0.04). Dual-task cadence was significantly lower for concussion participants than controls (89.5 [95% CI: 68.6-110.4] vs. 127.0 [95% CI: 97.4-156.6] steps/minute; p=0.04). Moderately-high to high correlations between tandem gait test time and whole-body COM medial-lateral displacement were detected at each time point during dual-task gait (r s =0.70-0.93; p=0.03-0.001). Adding a cognitive task during the tandem gait test resulted in longer detectable deficits post-concussion compared to the traditional single-task tandem gait test. As a clinical tool to assess dynamic motor function, tandem gait may assist with return to sport decisions after concussion. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

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

PubMed

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

2013-01-30

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. 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. 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.

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

PubMed Central

2013-01-01

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

De novo protein sequencing by combining top-down and bottom-up tandem mass spectra.

PubMed

Liu, Xiaowen; Dekker, Lennard J M; Wu, Si; Vanduijn, Martijn M; Luider, Theo M; Tolić, Nikola; Kou, Qiang; Dvorkin, Mikhail; Alexandrova, Sonya; Vyatkina, Kira; Paša-Tolić, Ljiljana; Pevzner, Pavel A

2014-07-03

There are two approaches for de novo protein sequencing: Edman degradation and mass spectrometry (MS). Existing MS-based methods characterize a novel protein by assembling tandem mass spectra of overlapping peptides generated from multiple proteolytic digestions of the protein. Because each tandem mass spectrum covers only a short peptide of the target protein, the key to high coverage protein sequencing is to find spectral pairs from overlapping peptides in order to assemble tandem mass spectra to long ones. However, overlapping regions of peptides may be too short to be confidently identified. High-resolution mass spectrometers have become accessible to many laboratories. These mass spectrometers are capable of analyzing molecules of large mass values, boosting the development of top-down MS. Top-down tandem mass spectra cover whole proteins. However, top-down tandem mass spectra, even combined, rarely provide full ion fragmentation coverage of a protein. We propose an algorithm, TBNovo, for de novo protein sequencing by combining top-down and bottom-up MS. In TBNovo, a top-down tandem mass spectrum is utilized as a scaffold, and bottom-up tandem mass spectra are aligned to the scaffold to increase sequence coverage. Experiments on data sets of two proteins showed that TBNovo achieved high sequence coverage and high sequence accuracy.

Heptameric (L12)6/L10 rather than canonical pentameric complexes are found by tandem MS of intact ribosomes from thermophilic bacteria.

PubMed

Ilag, Leopold L; Videler, Hortense; McKay, Adam R; Sobott, Frank; Fucini, Paola; Nierhaus, Knud H; Robinson, Carol V

2005-06-07

Ribosomes are universal translators of the genetic code into protein and represent macromolecular structures that are asymmetric, often heterogeneous, and contain dynamic regions. These properties pose considerable challenges for modern-day structural biology. Despite these obstacles, high-resolution x-ray structures of the 30S and 50S subunits have revealed the RNA architecture and its interactions with proteins for ribosomes from Thermus thermophilus, Deinococcus radiodurans, and Haloarcula marismortui. Some regions, however, remain inaccessible to these high-resolution approaches because of their high conformational dynamics and potential heterogeneity, specifically the so-called L7/L12 stalk complex. This region plays a vital role in protein synthesis by interacting with GTPase factors in translation. Here, we apply tandem MS, an approach widely applied to peptide sequencing for proteomic applications but not previously applied to MDa complexes. Isolation and activation of ions assigned to intact 30S and 50S subunits releases proteins S6 and L12, respectively. Importantly, this process reveals, exclusively while attached to ribosomes, a phosphorylation of L12, the protein located in multiple copies at the tip of the stalk complex. Moreover, through tandem MS we discovered a stoichiometry for the stalk protuberance on Thermus thermophilus and other thermophiles and contrast this assembly with the analogous one on ribosomes from mesophiles. Together with evidence for a potential interaction with the degradosome, these results show that important findings on ribosome structure, interactions, and modifications can be discovered by tandem MS, even on well studied ribosomes from Thermus thermophilus.

Heptameric (L12)6/L10 rather than canonical pentameric complexes are found by tandem MS of intact ribosomes from thermophilic bacteria

PubMed Central

Ilag, Leopold L.; Videler, Hortense; McKay, Adam R.; Sobott, Frank; Fucini, Paola; Nierhaus, Knud H.; Robinson, Carol V.

2005-01-01

Ribosomes are universal translators of the genetic code into protein and represent macromolecular structures that are asymmetric, often heterogeneous, and contain dynamic regions. These properties pose considerable challenges for modern-day structural biology. Despite these obstacles, high-resolution x-ray structures of the 30S and 50S subunits have revealed the RNA architecture and its interactions with proteins for ribosomes from Thermus thermophilus, Deinococcus radiodurans, and Haloarcula marismortui. Some regions, however, remain inaccessible to these high-resolution approaches because of their high conformational dynamics and potential heterogeneity, specifically the so-called L7/L12 stalk complex. This region plays a vital role in protein synthesis by interacting with GTPase factors in translation. Here, we apply tandem MS, an approach widely applied to peptide sequencing for proteomic applications but not previously applied to MDa complexes. Isolation and activation of ions assigned to intact 30S and 50S subunits releases proteins S6 and L12, respectively. Importantly, this process reveals, exclusively while attached to ribosomes, a phosphorylation of L12, the protein located in multiple copies at the tip of the stalk complex. Moreover, through tandem MS we discovered a stoichiometry for the stalk protuberance on Thermus thermophilus and other thermophiles and contrast this assembly with the analogous one on ribosomes from mesophiles. Together with evidence for a potential interaction with the degradosome, these results show that important findings on ribosome structure, interactions, and modifications can be discovered by tandem MS, even on well studied ribosomes from Thermus thermophilus. PMID:15923259

Evolutionary origins of a novel host plant detoxification gene in butterflies.

PubMed

Fischer, Hanna M; Wheat, Christopher W; Heckel, David G; Vogel, Heiko

2008-05-01

Chemical interactions between plants and their insect herbivores provide an excellent opportunity to study the evolution of species interactions on a molecular level. Here, we investigate the molecular evolutionary events that gave rise to a novel detoxifying enzyme (nitrile-specifier protein [NSP]) in the butterfly family Pieridae, previously identified as a coevolutionary key innovation. By generating and sequencing expressed sequence tags, genomic libraries, and screening databases we found NSP to be a member of an insect-specific gene family, which we characterized and named the NSP-like gene family. Members consist of variable tandem repeats, are gut expressed, and are found across Insecta evolving in a dynamic, ongoing birth-death process. In the Lepidoptera, multiple copies of single-domain major allergen genes are present and originate via tandem duplications. Multiple domain genes are found solely within the brassicaceous-feeding Pieridae butterflies, one of them being NSP and another called major allergen (MA). Analyses suggest that NSP and its paralog MA have a unique single-domain evolutionary origin, being formed by intragenic domain duplication followed by tandem whole-gene duplication. Duplicates subsequently experienced a period of relaxed constraint followed by an increase in constraint, perhaps after neofunctionalization. NSP and its ortholog MA are still experiencing high rates of change, reflecting a dynamic evolution consistent with the known role of NSP in plant-insect interactions. Our results provide direct evidence to the hypothesis that gene duplication is one of the driving forces for speciation and adaptation, showing that both within- and whole-gene tandem duplications are a powerful force underlying evolutionary adaptation.

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

PubMed

Li, Mingji; Wang, Junshu; Geng, Yanping; Li, Yikui; Wang, Qian; Liang, Quanfeng; Qi, Qingsheng

2012-02-06

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

Context-Sensitive Markov Models for Peptide Scoring and Identification from Tandem Mass Spectrometry

PubMed Central

Grover, Himanshu; Wallstrom, Garrick; Wu, Christine C.

2013-01-01

Abstract Peptide and protein identification via tandem mass spectrometry (MS/MS) lies at the heart of proteomic characterization of biological samples. Several algorithms are able to search, score, and assign peptides to large MS/MS datasets. Most popular methods, however, underutilize the intensity information available in the tandem mass spectrum due to the complex nature of the peptide fragmentation process, thus contributing to loss of potential identifications. We present a novel probabilistic scoring algorithm called Context-Sensitive Peptide Identification (CSPI) based on highly flexible Input-Output Hidden Markov Models (IO-HMM) that capture the influence of peptide physicochemical properties on their observed MS/MS spectra. We use several local and global properties of peptides and their fragment ions from literature. Comparison with two popular algorithms, Crux (re-implementation of SEQUEST) and X!Tandem, on multiple datasets of varying complexity, shows that peptide identification scores from our models are able to achieve greater discrimination between true and false peptides, identifying up to ∼25% more peptides at a False Discovery Rate (FDR) of 1%. We evaluated two alternative normalization schemes for fragment ion-intensities, a global rank-based and a local window-based. Our results indicate the importance of appropriate normalization methods for learning superior models. Further, combining our scores with Crux using a state-of-the-art procedure, Percolator, we demonstrate the utility of using scoring features from intensity-based models, identifying ∼4-8 % additional identifications over Percolator at 1% FDR. IO-HMMs offer a scalable and flexible framework with several modeling choices to learn complex patterns embedded in MS/MS data. PMID:23289783

Simultaneous quantification of 5 main components of Psoralea corylifolia L. in rats' plasma by utilizing ultra high pressure liquid chromatography tandem mass spectrometry.

PubMed

Gao, Qianqian; Xu, Zisheng; Zhao, Genhua; Wang, Heng; Weng, Zebin; Pei, Ke; Wu, Li; Cai, Baochang; Chen, Zhipeng; Li, Weidong

2016-02-01

Psoralea corylifolia L. has long been used in traditional Chinese medicine for treating and preventing many diseases. A group of flavonoid components are regarded as the active principals within the seeds. In this research, a rapid, accurate and sensitive ultra high pressure liquid chromatography tandem mass spectrometry (UHPLC/MS/MS) method has been established for simultaneous quantification of its 5 main components, namely, neobavaisoflavone, bavachin, isobavachalcone, bavachinin and corylifol A in rats' plasma after the rats were orally administrated with Buguzhi extract. Negative ion electrospray mode was applied in the detection process. Multiple reactions monitoring (MRM) mode was utilized for simultaneous quantitative analyzing of neobavaisoflavone (m/z 321.1→m/z 265.1), bavachin (m/z 323.1→m/z 119.0), isobavachalcone (m/z 323.2→m/z 119.0), bavachinin (m/z 337.2→m/z 119.0), corylifol A (m/z 389.2→m/z 277.0) and liquiritigenin (Internal Standard, m/z 255.1→m/z 119.0). Chromatographic separation of the above mentioned components was conducted on a Waters BEH-C18 column (100 mm×2.1mm, 1.7μm) with gradient elution system at flow rate of 0.3mL/min. The mobile phase was composed of acetonitrile and 0.1% formic acid solution. The lower limit of quantification (LLOQ) for each of the above analytes was 0.5ng/mL. Each of the analytes exhibited good linearity within the concentration range of 0.5-100ng/mL. The method was fully validated for its selectivity, accuracy, precision, stability, matrix effect and extraction recovery. The validated method has been successfully applied for simultaneous determination of the 5 flavonoids in rat plasma for the first time. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of 12 pharmaceuticals in water samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography with tandem mass spectrometry.

PubMed

Guan, Jin; Zhang, Chi; Wang, Yang; Guo, Yiguang; Huang, Peiting; Zhao, Longshan

2016-11-01

A new analytical method was developed for simultaneous determination of 12 pharmaceuticals using ultrasound-assisted dispersive liquid-liquid microextraction (DLLME) followed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). Six nonsteroidal anti-inflammatory drugs (NSAIDs, ketoprofen, mefenamic acid, tolfenamic acid, naproxen, sulindac, and piroxicam) and six antibiotics (tinidazole, cefuroxime axetil, ciprofloxacin, sulfamethoxazole, sulfadiazine, and chloramphenicol) were extracted by ultrasound-assisted DLLME using dichloromethane (800 μL) and methanol/acetonitrile (1:1, v/v, 1200 μL) as the extraction and dispersive solvents, respectively. The factors affecting the extraction efficiency, such as the type and volume of extraction and dispersive solvent, vortex and ultrasonic time, sample pH, and ionic strength, were optimized. The ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution by using a small volume of dispersive solvent, which increased the extraction efficiency and reduced the equilibrium time. Under the optimal conditions, the calibration curves showed good linearity in the range of 0.04-20 ng mL -1 (ciprofloxacin and sulfadiazine), 0.2-100 ng mL -1 (ketoprofen, tinidazole, cefuroxime axetil, naproxen, sulfamethoxazole, and sulindac), and 1-200 ng mL -1 (mefenamic acid, tolfenamic acid, piroxicam, and chloramphenicol). The LODs and LOQs of the method were in the range of 0.006-0.091 and 0.018-0.281 ng mL -1 , respectively. The relative recoveries of the target analytes were in the range from 76.77 to 99.97 % with RSDs between 1.6 and 8.8 %. The developed method was successfully applied to the extraction and analysis of 12 pharmaceuticals in five kinds of water samples (drinking water, running water, river water, influent and effluent wastewater) with satisfactory results. Graphical Abstract Twelve pharmaceuticals in water samples analyted by UHPLC-MS/MS using ultrasound-assisted DLLME.

An on-spot internal standard addition approach for accurately determining colistin A and colistin B in dried blood spots using ultra high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Tsai, I-Lin; Kuo, Ching-Hua; Sun, Hsin-Yun; Chuang, Yu-Chung; Chepyala, Divyabharathi; Lin, Shu-Wen; Tsai, Yun-Jung

2017-10-25

Outbreaks of multidrug-resistant Gram-negative bacterial infections have been reported worldwide. Colistin, an antibiotic with known nephrotoxicity and neurotoxicity, is now being used to treat multidrug-resistant Gram-negative strains. In this study, we applied an on-spot internal standard addition approach coupled with an ultra high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify colistin A and B from dried blood spots (DBSs). Only 15μL of whole blood was required for each sample. An internal standard with the same yield of extraction recoveries as colistin was added to the spot before sample extraction for accurate quantification. Formic acid in water (0.15%) with an equal volume of acetonitrile (50:50v/v) was used as the extraction solution. With the optimized extraction process and LC-MS/MS conditions, colistin A and B could be quantified from a DBS with respective limits of quantification of 0.13 and 0.27μgmL -1 , and the retention times were < 2min. The relative standard deviations of within-run and between-run precisions for peak area ratios were all < 17.3%. Accuracies were 91.5-111.2% for lower limit of quantification, low, medium, and high QC samples. The stability of the easily hydrolyzed prodrug, colistin methanesulfonate, was investigated in DBSs. Less than 4% of the prodrug was found to be hydrolyzed in DBSs at room temperature after 48h. The developed method applied an on-spot internal standard addition approach which benefited the precision and accuracy. Results showed that DBS sampling coupled with the sensitive LC-MS/MS method has the potential to be an alternative approach for colistin quantification, where the bias of prodrug hydrolysis in liquid samples is decreased. Copyright © 2017 Elsevier B.V. All rights reserved.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 1: Analysis and design of stages A, B, and C

NASA Technical Reports Server (NTRS)

Brent, J. A.; Cheatham, J. G.; Nilsen, A. W.

1972-01-01

A conventional rotor and stator, two dual-airfoil tandem rotors, and one dual-airfoil tandem stator were designed. The two tandem rotors were each designed with different percentages of the overall lift produced by the front airfoil. Velocity diagrams and blade leading and trailing edge metal angles selected for the conventional rotor and stator blading were used in the design of the tandem blading. Rotor inlet hub/tip ratio was 0.8. Design values of rotor tip velocity and stage pressure ratio were 757 ft/sec and 1.30, respectively.

Economic viability of thin-film tandem solar modules in the United States

NASA Astrophysics Data System (ADS)

Sofia, Sarah E.; Mailoa, Jonathan P.; Weiss, Dirk N.; Stanbery, Billy J.; Buonassisi, Tonio; Peters, I. Marius

2018-05-01

Tandem solar cells are more efficient but more expensive per unit area than established single-junction (SJ) solar cells. To understand when specific tandem architectures should be utilized, we evaluate the cost-effectiveness of different II-VI-based thin-film tandem solar cells and compare them to the SJ subcells. Levelized cost of electricity (LCOE) and energy yield are calculated for four technologies: industrial cadmium telluride and copper indium gallium selenide, and their hypothetical two-terminal (series-connected subcells) and four-terminal (electrically independent subcells) tandems, assuming record SJ quality subcells. Different climatic conditions and scales (residential and utility scale) are considered. We show that, for US residential systems with current balance-of-system costs, the four-terminal tandem has the lowest LCOE because of its superior energy yield, even though it has the highest US per watt (US W-1) module cost. For utility-scale systems, the lowest LCOE architecture is the cadmium telluride single junction, the lowest US W-1 module. The two-terminal tandem requires decreased subcell absorber costs to reach competitiveness over the four-terminal one.

A tandem approach for collocated measurements of microphysical and radiative cirrus properties

NASA Astrophysics Data System (ADS)

Klingebiel, Marcus; Ehrlich, André; Finger, Fanny; Röschenthaler, Timo; Jakirlić, Suad; Voigt, Matthias; Müller, Stefan; Maser, Rolf; Wendisch, Manfred; Hoor, Peter; Spichtinger, Peter; Borrmann, Stephan

2017-09-01

Microphysical and radiation measurements were collected with the novel AIRcraft TOwed Sensor Shuttle (AIRTOSS) - Learjet tandem platform. The platform is a combination of an instrumented Learjet 35A research aircraft and an aerodynamic bird, which is detached from and retracted back to the aircraft during flight via a steel wire with a length of 4000 m. Both platforms are equipped with radiative, cloud microphysical, trace gas, and meteorological instruments. The purpose of the development of this tandem set-up is to study the inhomogeneity of cirrus as well as other stratiform clouds. Sophisticated numerical flow simulations were conducted in order to optimally integrate an axially asymmetric Cloud Combination Probe (CCP) inside AIRTOSS. The tandem platform was applied during measurements at altitudes up to 36 000 ft (10 970 m) in the framework of the AIRTOSS - Inhomogeneous Cirrus Experiment (AIRTOSS-ICE). Ten flights were performed above the North Sea and Baltic Sea to probe frontal and in situ formed cirrus, as well as anvil outflow cirrus. For one flight, cirrus microphysical and radiative properties displayed significant inhomogeneities resolved by both measurement platforms. The CCP data show that the maximum of the observed particle number size distributions shifts with decreasing altitude from 30 to 300 µm, which is typical for frontal, midlatitude cirrus. Theoretical considerations imply that cloud particle aggregation inside the studied cirrus is very unlikely. Consequently, diffusional growth was identified to be the dominant microphysical growth process. Measurements of solar downward and upward irradiances at 670 nm wavelength were conducted above, below, and in the cirrus on both the Learjet and AIRTOSS. The observed variability of the downward irradiance below the cirrus reflects the horizontal heterogeneity of the observed thin cirrus. Vertically resolved solar heating rates were derived by either using single-platform measurements at different altitudes or by making use of the collocated irradiance measurements at different altitudes of the tandem platform. Due to unavoidable biases of the measurements between the individual flight legs, the single-platform approach failed to provide a realistic solar heating rate profile, while the uncertainties of the tandem approach are reduced. Here, the solar heating rates range up to 6 K day-1 at top of the cirrus layer.

Base Excision Repair of Tandem Modifications in a Methylated CpG Dinucleotide*

PubMed Central

Sassa, Akira; Çağlayan, Melike; Dyrkheeva, Nadezhda S.; Beard, William A.; Wilson, Samuel H.

2014-01-01

Cytosine methylation and demethylation in tracks of CpG dinucleotides is an epigenetic mechanism for control of gene expression. The initial step in the demethylation process can be deamination of 5-methylcytosine producing the TpG alteration and T:G mispair, and this step is followed by thymine DNA glycosylase (TDG) initiated base excision repair (BER). A further consideration is that guanine in the CpG dinucleotide may become oxidized to 7,8-dihydro-8-oxoguanine (8-oxoG), and this could affect the demethylation process involving TDG-initiated BER. However, little is known about the enzymology of BER of altered in-tandem CpG dinucleotides; e.g. Tp8-oxoG. Here, we investigated interactions between this altered dinucleotide and purified BER enzymes, the DNA glycosylases TDG and 8-oxoG DNA glycosylase 1 (OGG1), apurinic/apyrimidinic (AP) endonuclease 1, DNA polymerase β, and DNA ligases. The overall TDG-initiated BER of the Tp8-oxoG dinucleotide is significantly reduced. Specifically, TDG and DNA ligase activities are reduced by a 3′-flanking 8-oxoG. In contrast, the OGG1-initiated BER pathway is blocked due to the 5′-flanking T:G mispair; this reduces OGG1, AP endonuclease 1, and DNA polymerase β activities. Furthermore, in TDG-initiated BER, TDG remains bound to its product AP site blocking OGG1 access to the adjacent 8-oxoG. These results reveal BER enzyme specificities enabling suppression of OGG1-initiated BER and coordination of TDG-initiated BER at this tandem alteration in the CpG dinucleotide. PMID:24695738

Extending a Tandem Mass Spectral Library to Include MS2 Spectra of Fragment Ions Produced In-Source and MSn Spectra.

PubMed

Yang, Xiaoyu; Neta, Pedatsur; Stein, Stephen E

2017-11-01

Tandem mass spectral library searching is finding increased use as an effective means of determining chemical identity in mass spectrometry-based omics studies. We previously reported on constructing a tandem mass spectral library that includes spectra for multiple precursor ions for each analyte. Here we report our method for expanding this library to include MS 2 spectra of fragment ions generated during the ionization process (in-source fragment ions) as well as MS 3 and MS 4 spectra. These can assist the chemical identification process. A simple density-based clustering algorithm was used to cluster all significant precursor ions from MS 1 scans for an analyte acquired during an infusion experiment. The MS 2 spectra associated with these precursor ions were grouped into the same precursor clusters. Subsequently, a new top-down hierarchical divisive clustering algorithm was developed for clustering the spectra from fragmentation of ions in each precursor cluster, including the MS 2 spectra of the original precursors and of the in-source fragments as well as the MS n spectra. This algorithm starts with all the spectra of one precursor in one cluster and then separates them into sub-clusters of similar spectra based on the fragment patterns. Herein, we describe the algorithms and spectral evaluation methods for extending the library. The new library features were demonstrated by searching the high resolution spectra of E. coli extracts against the extended library, allowing identification of compounds and their in-source fragment ions in a manner that was not possible before. Graphical Abstract ᅟ.

Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging.

PubMed

Pedersen, E B L; Angmo, D; Dam, H F; Thydén, K T S; Andersen, T R; Skjønsfjell, E T B; Krebs, F C; Holler, M; Diaz, A; Guizar-Sicairos, M; Breiby, D W; Andreasen, J W

2015-08-28

Organic solar cells have great potential for upscaling due to roll-to-roll processing and a low energy payback time, making them an attractive sustainable energy source for the future. Active layers coated with water-dispersible Landfester particles enable greater control of the layer formation and easier access to the printing industry, which has reduced the use of organic solvents since the 1980s. Through ptychographic X-ray computed tomography (PXCT), we image quantitatively a roll-to-roll coated photovoltaic tandem stack consisting of one bulk heterojunction active layer and one Landfester particle active layer. We extract the layered morphology with structural and density information including the porosity present in the various layers and the silver electrode with high resolution in 3D. The Landfester particle layer is found to have an undesired morphology with negatively correlated top- and bottom interfaces, wide thickness distribution and only partial surface coverage causing electric short circuits through the layer. By top coating a polymer material onto the Landfester nanoparticles we eliminate the structural defects of the layer such as porosity and roughness, and achieve the increased performance larger than 1 V expected for a tandem cell. This study highlights that quantitative imaging of weakly scattering stacked layers of organic materials has become feasible by PXCT, and that this information cannot be obtained by other methods. In the present study, this technique specifically reveals the need to improve the coatability and layer formation of Landfester nanoparticles, thus allowing improved solar cells to be produced.

Photodegradation of the novel fungicide fluopyram in aqueous solution: kinetics, transformation products, and toxicity evolvement.

PubMed

Dong, Bizhang; Hu, Jiye

2016-10-01

The aqueous photodegradation of fluopyram was investigated under UV light (λ ≥ 200 nm) and simulated sunlight irradiation (λ ≥ 290 nm). The effect of solution pH, fulvic acids (FA), nitrate (NO3 (-)), Fe (III) ions, and titanium dioxide (TiO2) on direct photolysis of fluopyram was explored. The results showed that fluopyram photodegradation was faster in neutral solution than that in acidic and alkaline solutions. The presence of FA, NO3 (-), Fe (III), and TiO2 slightly affected the photodegradation of fluopyram under UV irradiation, whereas the photodegradation rates of fluopyram with 5 mg L(-1) Fe (III) and 500 mg L(-1) TiO2 were about 7-fold and 13-fold faster than that without Fe (III) and TiO2 under simulated sunlight irradiation, respectively. Three typical products for direct photolysis of fluopyram have been isolated and characterized by liquid chromatography tandem mass spectrometry. These products resulted from the intramolecular elimination of HCl, hydroxyl-substitution, and hydrogen extraction. Based on the identified transformation products and evolution profile, a plausible degradation pathway for the direct photolysis of fluopyram in aqueous solution was proposed. In addition, acute toxicity assays using the Vibrio fischeri bacteria test indicated that the transformation products were more toxic than the parent compound.

Numerical investigation & comparison of a tandem-bladed turbocharger centrifugal compressor stage with conventional design

NASA Astrophysics Data System (ADS)

Danish, Syed Noman; Qureshi, Shafiq Rehman; EL-Leathy, Abdelrahman; Khan, Salah Ud-Din; Umer, Usama; Ma, Chaochen

2014-12-01

Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional compressor. Stage characteristics are explored for various tip clearance levels, axial spacings and circumferential clockings. Conventional impeller was modified to tandem-bladed design with no modifications in backsweep angle, meridional gas passage and camber distributions in order to have a true comparison with conventional design. Performance degradation is observed for both the conventional and tandem designs with increase in tip clearance. Linear-equation models for correlating stage characteristics with tip clearance are proposed. Comparing two designs, it is clearly evident that the conventional design shows better performance at moderate flow rates. However; near choke flow, tandem design gives better results primarily because of the increase in throat area. Surge point flow rate also seems to drop for tandem compressor resulting in increased range of operation.

Isolation of human simple repeat loci by hybridization selection.

PubMed

Armour, J A; Neumann, R; Gobert, S; Jeffreys, A J

1994-04-01

We have isolated short tandem repeat arrays from the human genome, using a rapid method involving filter hybridization to enrich for tri- or tetranucleotide tandem repeats. About 30% of clones from the enriched library cross-hybridize with probes containing trimeric or tetrameric tandem arrays, facilitating the rapid isolation of large numbers of clones. In an initial analysis of 54 clones, 46 different tandem arrays were identified. Analysis of these tandem repeat loci by PCR showed that 24 were polymorphic in length; substantially higher levels of polymorphism were displayed by the tetrameric repeat loci isolated than by the trimeric repeats. Primary mapping of these loci by linkage analysis showed that they derive from 17 chromosomes, including the X chromosome. We anticipate the use of this strategy for the efficient isolation of tandem repeats from other sources of genomic DNA, including DNA from flow-sorted chromosomes, and from other species.

[Polymorphic loci and polymorphism analysis of short tandem repeats within XNP gene].

PubMed

Liu, Qi-Ji; Gong, Yao-Qin; Guo, Chen-Hong; Chen, Bing-Xi; Li, Jiang-Xia; Guo, Yi-Shou

2002-01-01

To select polymorphic short tandem repeat markers within X-linked nuclear protein (XNP) gene, genomic clones which contain XNP gene were recognized by homologous analysis with XNP cDNA. By comparing the cDNA with genomic DNA, non-exonic sequences were identified, and short tandem repeats were selected from non-exonic sequences by using BCM search Launcher. Polymorphisms of the short tandem repeats in Chinese population were evaluated by PCR amplification and PAGE. Five short tandem repeats were identified from XNP gene, two of which were polymorphic. Four and 11 alleles were observed in Chinese population for XNPSTR1 and XNPSTR4, respectively. Heterozygosities were 47% for XNPSTR1 and 70% for XNPSTR4. XNPSTR1 and XNPSTR4 localized within 3' end and intron 10, respectively. Two polymorphic short tandem repeats have been identified within XNP gene and will be useful for linkage analysis and gene diagnosis of XNP gene.

Characterization of aromatic organosulfur model compounds relevant to fossil fuels by using atmospheric pressure chemical ionization with CS2 and high-resolution tandem mass spectrometry.

PubMed

Tang, Weijuan; Sheng, Huaming; Jin, Chunfen; Riedeman, James S; Kenttämaa, Hilkka I

2016-04-15

The chemistry of desulfurization involved in processing crude oil is greatly dependent on the forms of sulfur in the oil. Sulfur exists in different chemical bonding environments in fossil fuels, including those in thiophenes and benzothiophenes, thiols, sulfides, and disulfides. In this study, the fragmentation behavior of the molecular ions of 17 aromatic organosulfur compounds with various functionalities was systematically investigated by using high-resolution tandem mass spectrometry. Multiple-stage tandem mass spectrometric experiments were carried out using a linear quadrupole ion trap (LQIT) equipped with an atmospheric pressure chemical ionization (APCI) source. (+)APCI/CS2 was used to generate stable dominant molecular ions for all the compounds studied except for three sulfides that also showed abundant fragment ions. The LQIT coupled with an orbitrap mass spectrometer was used for elemental composition analysis, which facilitated the identification of the neutral molecules lost during fragmentation. The characteristic fragment ions generated in MS(2) and MS(3) experiments provide clues for the chemical bonding environment of sulfur atoms in the examined compounds. Upon collision-induced dissociation (CID), the molecular ions can lose the sulfur atom in a variety of ways, including as S (32 Da), HS(•) (33 Da), H2 S (34 Da), CS (44 Da), (•) CHS (45 Da) and CH2 S (46 Da). These neutral fragments are not only indicative of the presence of sulfur, but also of the type of sulfur present in the compound. Generally, losses of HS(•) and H2 S were found to be associated with compounds containing saturated sulfur functionalities, while losses of S, CS and (•) CHS were more common for heteroaromatic sulfur compounds. High-resolution tandem mass spectrometry with APCI/CS2 ionization is a viable approach to determining the types of organosulfur compounds. It can potentially be applied to analysis of complex mixtures, which is beneficial to improving the desulfurization process of fossil fuels. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Domino reactions initiated by intramolecular hydride transfers from tri(di)arylmethane fragments to ketenimine and carbodiimide functions.

PubMed

Alajarin, Mateo; Bonillo, Baltasar; Ortin, Maria-Mar; Sanchez-Andrada, Pilar; Vidal, Angel; Orenes, Raul-Angel

2010-10-21

The ability of triarylmethane and diarylmethane fragments to behave as hydride donors participating in thermal [1,5]-H shift/6π-ERC tandem processes involving ketenimine and carbodiimide functions is disclosed. C-Alkyl-C-phenyl ketenimines N-substituted by a triarylmethane substructure convert into a variety of 3,3,4,4-tetrasubstituted-3,4-dihydroquinolines, as structurally related carbodiimides transform into 3,4,4-trisubstituted-3,4-dihydroquinazolines via transient ortho-azaxylylenes. The first step of these one-pot conversions, the [1,5]-H shift, is considered to be a hydride migration on the basis of the known hydricity of the tri(di)arylmethane fragment and the electrophilicity of the central heterocumulenic carbon atom, whereas the final electrocyclization involves the formation of a sterically congested C-C or C-N bond. In the cases of C,C-diphenyl substituted triarylmethane-ketenimines the usual 6π-ERC becomes prohibited by the presence of two phenyl rings at each end of the azatrienic system. This situation opens new reaction channels: (a) following the initial hydride shift, the tandem sequence continues with an alternative electrocyclization mode to give 9,10-dihydroacridines, (b) the full sequence is initiated by a rare 1,5 migration of an electron-rich aryl group, followed by a 6π-ERC which leads to 2-aryl-3,4-dihydroquinolines, or (c) a different [1,5]-H shift/6π-ERC sequence involving the initial migration of a hydrogen atom from a methyl group at the ortho position to the nitrogen atom of the ketenimine function. Diarylmethane-ketenimines bearing a methyl group at the benzylic carbon atom experience a tandem double [1,5]-H shift, the first one being the usual benzylic hydride transfer whereas the second one involves the methyl group at the initial benzylic carbon atom, the reaction products being 2-aminostyrenes. Diarylmethane-ketenimines lacking such a methyl group convert into 3,4-dihydroquinolines by the habitual tandem [1,5]-H shift/6π-ERC processes.

Solution structure of leptospiral LigA4 Big domain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mei, Song; Zhang, Jiahai; Zhang, Xuecheng

Pathogenic Leptospiraspecies express immunoglobulin-like proteins which serve as adhesins to bind to the extracellular matrices of host cells. Leptospiral immunoglobulin-like protein A (LigA), a surface exposed protein containing tandem repeats of bacterial immunoglobulin-like (Big) domains, has been proved to be involved in the interaction of pathogenic Leptospira with mammalian host. In this study, the solution structure of the fourth Big domain of LigA (LigA4 Big domain) from Leptospira interrogans was solved by nuclear magnetic resonance (NMR). The structure of LigA4 Big domain displays a similar bacterial immunoglobulin-like fold compared with other Big domains, implying some common structural aspects of Bigmore » domain family. On the other hand, it displays some structural characteristics significantly different from classic Ig-like domain. Furthermore, Stains-all assay and NMR chemical shift perturbation revealed the Ca{sup 2+} binding property of LigA4 Big domain. - Highlights: • Determining the solution structure of a bacterial immunoglobulin-like domain from a surface protein of Leptospira. • The solution structure shows some structural characteristics significantly different from the classic Ig-like domains. • A potential Ca{sup 2+}-binding site was identified by strains-all and NMR chemical shift perturbation.« less

A workflow for large-scale empirical identification of cell wall N-linked glycoproteins of tomato (Solanum lycopersicum) fruit by tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

Glycosylation is a common post-translational modification of plant proteins that impacts a large number of important biological processes. Nevertheless, the impacts of differential site occupancy and the nature of specific glycoforms are obscure. Historically, characterization of glycoproteins has b...

Integral bypass diodes in an amorphous silicon alloy photovoltaic module

NASA Technical Reports Server (NTRS)

Hanak, J. J.; Flaisher, H.

1991-01-01

Thin-film, tandem-junction, amorphous silicon (a-Si) photovoltaic modules were constructed in which a part of the a-Si alloy cell material is used to form bypass protection diodes. This integral design circumvents the need for incorporating external, conventional diodes, thus simplifying the manufacturing process and reducing module weight.

The Co-Evolution of Knowledge and Event Memory

ERIC Educational Resources Information Center

Nelson, Angela B.; Shiffrin, Richard M.

2013-01-01

We present a theoretical framework and a simplified simulation model for the co-evolution of knowledge and event memory, both termed SARKAE (Storing and Retrieving Knowledge and Events). Knowledge is formed through the accrual of individual events, a process that operates in tandem with the storage of individual event memories. In 2 studies, new…

Proteomic analysis of Taenia ovis metacestodes by high performance liquid chromatography-coupled tandem mass spectrometry.

PubMed

Zheng, Yadong

2017-03-15

Taenia ovis metacestodes reside in the muscle of sheep and goats, and may cause great economic loss due to condemnation of carcasses if not effectively controlled. Although advances have been made in the control of T. ovis infection, our knowledge of T. ovis biology is limited. Herein the protein profiling of T. ovis metacestodes was determined by liquid chromatography-linked tandem mass spectrometry. A total of 966 proteins were identified and 25.1% (188/748) were annotated to be associated with metabolic pathways. Consistently, GO analysis returned a metabolic process (16.27%) as one of two main biological process terms. Moreover, it was found that 24 proteins, including very low-density lipoprotein receptor, enolase, paramyosin and endophilin B1, were abundant in T. ovis metacestodes. These proteins may be associated with motility, metabolism, signaling, stress, drug resistance and immune responses. Furthermore, comparative analysis of 5 cestodes revealed the presence of Taenia-specific enolases. These data provide clues for better understanding of T. ovis biology, which is informative for effective control of infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of processing contaminants in edible oils. Part 2. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol and 2-monochloropropanediol diesters.

PubMed

MacMahon, Shaun; Begley, Timothy H; Diachenko, Gregory W

2013-05-22

A method was developed and validated for the detection of fatty acid diesters of 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) in edible oils. These analytes are potentially carcinogenic chemical contaminants formed during edible oil processing. After separation from oil matrices using a two-step solid-phase extraction (SPE) procedure, the target compounds are quantitated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). The first chromatographic conditions have been developed that separate intact diesters of 2-MCPD and 3-MCPD, allowing for their individual quantitation. The method has been validated for 28 3-MCPD diesters of lauric, myristic, palmitic, linolenic, linoleic, oleic, and stearic acids in coconut, olive, and palm oils, as well as 3 2-MCPD diesters, using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 88-118% (2-16% RSD) with maximum limits of quantitation of 30 ng/g (ppb).

InP/Ga0.47In0.53As monolithic, two-junction, three-terminal tandem solar cells

NASA Technical Reports Server (NTRS)

Wanlaas, M. W.; Gessert, T. A.; Horner, G. S.; Emery, K. A.; Coutts, T. J.

1991-01-01

The work presented has focussed on increasing the efficiency of InP-based solar cells through the development of a high-performance InP/Ga(0.47)In(0.53)As two-junction, three-terminal monolithic tandem cell. Such a tandem is particularly suited to space applications where a radiation-hard top cell (i.e., InP) is required. Furthermore, the InP/Ga(0.47)In(0.53)As materials system is lattice matched and offers a top cell/bottom cell bandgap differential (0.60 eV at 300 K) suitable for high tandem cell efficiencies under AMO illumination. A three-terminal configuration was chosen since it allows for independent power collection from each subcell in the monolithic stack, thus minimizing the adverse impact of radiation damage on the overall tandem efficiency. Realistic computer modeling calculations predict an efficiency boost of 7 to 11 percent from the Ga(0.47)In(0.53)As bottom cell under AMO illumination (25 C) for concentration ratios in the 1 to 1000 range. Thus, practical AMO efficiencies of 25 to 32 percent appear possible with the InP/Ga(0.47)In(0.53)As tandem cell. Prototype n/p/n InP/Ga(0.47)In(0.53)As monolithic tandem cells were fabricated and tested successfully. Using an aperture to define the illuminated areas, efficiency measurements performed on a non-optimized device under standard global illumination conditions (25 C) with no antireflection coating (ARC) give 12.2 percent for the InP top cell and 3.2 percent for the Ga(0.47)In(0.53)As bottom cell, yielding an overall tandem efficiency of 15.4 percent. With an ARC, the tandem efficiency could reach approximately 22 percent global and approximately 20 percent AMO. Additional details regarding the performance of individual InP and Ga(0.47)In(0.53)As component cells, fabrication and operation of complete tandem cells and methods for improving the tandem cell performance, are also discussed.

Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: II. Determination of amphetamine in human urine samples by liquid chromatography-tandem mass spectrometry.

PubMed

El-Beqqali, Aziza; Andersson, Lars I; Jeppsson, Amin Dadoun; Abdel-Rehim, Mohamed

2017-09-15

Amphetamine selective molecularly imprinted sol-gel polymer tablets, MIP-tablets, for solid-phase microextraction of biofluid samples were prepared. An acetonitrile solution of deuterated amphetamine template and silane precursor, 3-(propylmethacrylate) trimethoxysilane, was soaked into the pores of polyethylene tablet substrates and polymerized by an acid-catalysed sol-gel process. Application of the resultant MIP-tablets to extract amphetamine from human urine samples followed by LC-MS/MS analysis was investigated. The extraction protocol was optimised with respect to pH of sample, addition of sodium chloride, extraction time, desorption solvent and desorption time. The final analysis method determined amphetamine in human urine with a limit of detection (LOD) of 1.0ng/mL and a lower limit of quantification (LLOQ) of 5ng/mL. Validation demonstrated accuracy of the method was 91.0-104.0% and inter-assay precision was 4.8-8.5% (RSD). Extraction recovery was 80%. The MIP-tablets could be re-used and the same tablet could be employed for more than twenty extractions. Copyright © 2017 Elsevier B.V. All rights reserved.

Compositionally Graded Absorber for Efficient and Stable Near‐Infrared‐Transparent Perovskite Solar Cells

PubMed Central

Pisoni, Stefano; Weiss, Thomas P.; Feurer, Thomas; Wäckerlin, Aneliia; Fuchs, Peter; Nishiwaki, Shiro; Zortea, Lukas; Tiwari, Ayodhya N.

2018-01-01

Abstract Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se2, CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite solar cells under long‐term heat/light soaking has not been demonstrated. In this study, a facile partial ion‐exchange approach is reported to achieve compositionally graded perovskite absorber layers. Incorporating compositional grading improves charge collection and suppresses interface recombination, enabling to fabricate near‐infrared‐transparent perovskite solar cells with power conversion efficiency of 16.8% in substrate configuration, and demonstrate 22.7% tandem efficiency with 3.3% absolute gain when mechanically stacked on a Cu(In,Ga)Se2 bottom cell. Non‐encapsulated graded perovskite device retains over 93% of its initial efficiency after 1000 h operation at maximum power point at 60 °C under equivalent 1 sun illumination. The results open an avenue in exploring partial ion‐exchange to design graded perovskite solar cells with improved efficiency and stability. PMID:29593970

Compositionally Graded Absorber for Efficient and Stable Near-Infrared-Transparent Perovskite Solar Cells.

PubMed

Fu, Fan; Pisoni, Stefano; Weiss, Thomas P; Feurer, Thomas; Wäckerlin, Aneliia; Fuchs, Peter; Nishiwaki, Shiro; Zortea, Lukas; Tiwari, Ayodhya N; Buecheler, Stephan

2018-03-01

Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se 2 , CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite solar cells under long-term heat/light soaking has not been demonstrated. In this study, a facile partial ion-exchange approach is reported to achieve compositionally graded perovskite absorber layers. Incorporating compositional grading improves charge collection and suppresses interface recombination, enabling to fabricate near-infrared-transparent perovskite solar cells with power conversion efficiency of 16.8% in substrate configuration, and demonstrate 22.7% tandem efficiency with 3.3% absolute gain when mechanically stacked on a Cu(In,Ga)Se 2 bottom cell. Non-encapsulated graded perovskite device retains over 93% of its initial efficiency after 1000 h operation at maximum power point at 60 °C under equivalent 1 sun illumination. The results open an avenue in exploring partial ion-exchange to design graded perovskite solar cells with improved efficiency and stability.

Determining orientation and direction of DNA sequences

DOEpatents

Goodwin, Edwin H.; Meyne, Julianne

2000-01-01

Determining orientation and direction of DNA sequences. A method by which fluorescence in situ hybridization can be made strand specific is described. Cell cultures are grown in a medium containing a halogenated nucleotide. The analog is partially incorporated in one DNA strand of each chromatid. This substitution takes place in opposite strands of the two sister chromatids. After staining with the fluorescent DNA-binding dye Hoechst 33258, cells are exposed to long-wavelength ultraviolet light which results in numerous strand nicks. These nicks enable the substituted strand to be denatured and solubilized by heat, treatment with high or low pH aqueous solutions, or by immersing the strands in 2.times.SSC (0.3M NaCl+0.03M sodium citrate), to name three procedures. It is unnecessary to enzymatically digest the strands using Exo III or another exonuclease in order to excise and solubilize nucleotides starting at the sites of the nicks. The denaturing/solubilizing process removes most of the substituted strand while leaving the prereplication strand largely intact. Hybridization of a single-stranded probe of a tandem repeat arranged in a head-to-tail orientation will result in hybridization only to the chromatid with the complementary strand present.

Metal Doping to Enhance the Photoelectrochemical Behavior of LaFeO3 Photocathodes.

PubMed

Díez-García, María Isabel; Gómez, Roberto

2017-06-09

The development of tandem devices for water photosplitting requires the preparation of photocathodic materials based on earth-abundant elements that show long-term stability in aqueous electrolytes. Ternary metal oxides seem to be a viable option, among which perovskites stand out. In this context, transparent and compact LaFeO 3 thin-film electrodes have been prepared by a sol-gel process, both undoped and doped with metals (M) such as Mg or Zn. Pristine electrodes support the development of cathodic photocurrents in 0.1 m NaOH aqueous solutions, particularly in the presence of oxygen, with an onset potential as high as 1.4 V versus the reversible hydrogen electrode. Doping with Mg or Zn leads to an important enhancement of the photocurrent, which peaks for a stoichiometry of LaFe 0.95 M 0.05 O 3 with a sixfold enhancement with respect to the pristine material. Such an improvement is attributed to an increase in both the density and mobility of the majority carriers, although a contribution of surface passivation cannot be excluded. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tandem Repeat Proteins Inspired By Squid Ring Teeth

NASA Astrophysics Data System (ADS)

Pena-Francesch, Abdon

Proteins are large biomolecules consisting of long chains of amino acids that hierarchically assemble into complex structures, and provide a variety of building blocks for biological materials. The repetition of structural building blocks is a natural evolutionary strategy for increasing the complexity and stability of protein structures. However, the relationship between amino acid sequence, structure, and material properties of protein systems remains unclear due to the lack of control over the protein sequence and the intricacies of the assembly process. In order to investigate the repetition of protein building blocks, a recently discovered protein from squids is examined as an ideal protein system. Squid ring teeth are predatory appendages located inside the suction cups that provide a strong grasp of prey, and are solely composed of a group of proteins with tandem repetition of building blocks. The objective of this thesis is the understanding of sequence, structure and property relationship in repetitive protein materials inspired in squid ring teeth for the first time. Specifically, this work focuses on squid-inspired structural proteins with tandem repeat units in their sequence (i.e., repetition of alternating building blocks) that are physically cross-linked via beta-sheet structures. The research work presented here tests the hypothesis that, in these systems, increasing the number of building blocks in the polypeptide chain decreases the protein network defects and improves the material properties. Hence, the sequence, nanostructure, and properties (thermal, mechanical, and conducting) of tandem repeat squid-inspired protein materials are examined. Spectroscopic structural analysis, advanced materials characterization, and entropic elasticity theory are combined to elucidate the structure and material properties of these repetitive proteins. This approach is applied not only to native squid proteins but also to squid-inspired synthetic polypeptides that allow for a fine control of the sequence and network morphology. The results provided in this work establish a clear dependence between the repetitive building blocks, the network morphology, and the properties of squid-inspired repetitive protein materials. Increasing the number of tandem repeat units in SRT-inspired proteins led to more effective protein networks with superior properties. Through increasing tandem repetition and optimization of network morphology, highly efficient protein materials capable of withstanding deformations up to 400% of their original length, with MPa-GPa modulus, high energy absorption (50 MJ m-3), peak proton conductivity of 3.7 mS cm-1 (at pH 7, highest reported to date for biological materials), and peak thermal conductivity of 1.4 W m-1 K -1 (which exceeds that of most polymer materials) were developed. These findings introduce new design rules in the engineering of proteins based on tandem repetition and morphology control, and provide a novel framework for tailoring and optimizing the properties of protein-based materials.

The application of high-resolution mass spectrometry-based data-mining tools in tandem to metabolite profiling of a triple drug combination in humans.

PubMed

Xing, Jie; Zang, Meitong; Zhang, Haiying; Zhu, Mingshe

2015-10-15

Patients are usually exposed to multiple drugs, and metabolite profiling of each drug in complex biological matrices is a big challenge. This study presented a new application of an improved high resolution mass spectrometry (HRMS)-based data-mining tools in tandem to fast and comprehensive metabolite identification of combination drugs in human. The model drug combination was metronidazole-pantoprazole-clarithromycin (MET-PAN-CLAR), which is widely used in clinic to treat ulcers caused by Helicobacter pylori. First, mass defect filter (MDF), as a targeted data processing tool, was able to recover all relevant metabolites of MET-PAN-CLAR in human plasma and urine from the full-scan MS dataset when appropriate MDF templates for each drug were defined. Second, the accurate mass-based background subtraction (BS), as an untargeted data-mining tool, worked effectively except for several trace metabolites, which were buried in the remaining background signals. Third, an integrated strategy, i.e., untargeted BS followed by improved MDF, was effective for metabolite identification of MET-PAN-CLAR. Most metabolites except for trace ones were found in the first step of BS-processed datasets, and the results led to the setup of appropriate metabolite MDF template for the subsequent MDF data processing. Trace metabolites were further recovered by MDF, which used both common MDF templates and the novel metabolite-based MDF templates. As a result, a total of 44 metabolites or related components were found for MET-PAN-CLAR in human plasma and urine using the integrated strategy. New metabolic pathways such as N-glucuronidation of PAN and dehydrogenation of CLAR were found. This study demonstrated that the combination of accurate mass-based multiple data-mining techniques in tandem, i.e., untargeted background subtraction followed by targeted mass defect filtering, can be a valuable tool for rapid metabolite profiling of combination drugs in vivo. Copyright © 2015 Elsevier B.V. All rights reserved.

Knockdown of Rice microRNA166 by Short Tandem Target Mimic (STTM).

PubMed

Teotia, Sachin; Zhang, Dabing; Tang, Guiliang

2017-01-01

Small RNAs, including microRNAs (miRNAs), are abundant in plants and play key roles in controlling plant development and physiology. miRNAs regulate the expression of the target genes involved in key plant processes. Due to functional redundancy among miRNA family members in plants, an ideal approach to silence the expression of all members simultaneously, for their functional characterization, is desirable. Target mimic (TM) was the first approach to achieve this goal. Short tandem target mimic (STTM) is a potent approach complementing TM for silencing miRNAs in plants. STTMs have been successfully used in dicots to block miRNA functions. Here, we describe in detail the protocol for designing STTM construct to block miRNA functions in rice. Such approach can be applied to silence miRNAs in other monocots as well.

Effect of remote inductively coupled plasma (ICP) on the electron energy probability function of an in-tandem main ICP

NASA Astrophysics Data System (ADS)

Lee, Jaewon; Kim, Kyung-Hyun; Chung, Chin-Wook

2017-02-01

The remote plasma has been generally used as the auxiliary plasma source for indirect plasma processes such as cleaning or ashing. When tandem plasma sources that contain main and remote plasma sources are discharged, the main plasma is affected by the remote plasma and vice versa. Charged particles can move between two chambers due to the potential difference between the two plasmas. For this reason, the electron energy possibility function of the main plasma can be controlled by adjusting the remote plasma state. In our study, low energy electrons in the main plasma are effectively heated with varying remote plasma powers, and high energy electrons which overcome potential differences between two plasmas—are exchanged with no remarkable change in the plasma density and the effective electron temperature.

Studies of the Lateral-Directional Flying Qualities of a Tandem Helicopter in Forward Flight

NASA Technical Reports Server (NTRS)

Amer, Kenneth B; Tapscott, Robert J

1954-01-01

An investigation of the lateral-directional flying qualities of a tandem-rotor helicopter in forward flight was undertaken to determine desirable goals for helicopter lateral-directional flying qualities and possible methods of achieving these goals in the tandem-rotor helicopter. Comparison between directional stability as measured in flight and rotor-off model tests in a wind tunnel shows qualitative agreement and, hence, indicates such wind-tunnel test, despite the absence of the rotors, to be one effective method of studying means of improving the directional stability of the tandem helicopter. Flight-test measurements of turns and oscillations, in conjunction with analytical studies, suggest possible practical methods of achieving the goals of satisfactory turn and oscillatory characteristics in the tandem helicopter.

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

PubMed

Sivula, Kevin

2013-01-01

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.

Semi-transparent perovskite solar cells for tandems with silicon and CIGS

DOE PAGES

Bailie, Colin D.; Christoforo, M. Greyson; Mailoa, Jonathan P.; ...

2014-12-23

A promising approach for upgrading the performance of an established low-bandgap solar technology without adding much cost is to deposit a high bandgap polycrystalline semiconductor on top to make a tandem solar cell. We use a transparent silver nanowire electrode on perovskite solar cells to achieve a semi-transparent device. We place the semi-transparent cell in a mechanically-stacked tandem configuration onto copper indium gallium diselenide (CIGS) and low-quality multicrystalline silicon (Si) to achieve solid-state polycrystalline tandem solar cells with a net improvement in efficiency over the bottom cell alone. Furthermore, this work paves the way for integrating perovskites into a low-costmore » and high-efficiency (>25%) tandem cell.« less

Tandem Repeated Irritation Test (TRIT) Studies and Clinical Relevance: Post 2006.

PubMed

Reddy, Rasika; Maibach, Howard

2018-06-11

Single or multiple applications of irritants can lead to occupational contact dermatitis, and most commonly irritant contact dermatitis (ICD). Tandem irritation, the sequential application of two irritants to a target skin area, has been studied using the Tandem Repeated Irritation Test (TRIT) to provide a more accurate representation of skin irritation. Here we present an update to Kartono's review on tandem irritation studies since 2006 [1]. We surveyed the literature available on PubMed, Embase, Google Scholar, and the UCSF Dermatology library databases since 2006. The studies included discuss the tandem effects of common chemical irritants, organic solvents, occlusion as well as clinical relevance - and enlarge our ability to discern whether multiple chemical exposures are more or less likely to enhance irritation.

Bioavailability study of dronabinol oral solution versus dronabinol capsules in healthy volunteers

PubMed Central

Parikh, Neha; Kramer, William G; Khurana, Varun; Cognata Smith, Christina; Vetticaden, Santosh

2016-01-01

Background Dronabinol, a pharmaceutical Δ-9-tetrahydrocannabinol, was originally developed as an oral capsule. This study evaluated the bioavailability of a new formulation, dronabinol oral solution, versus a dronabinol capsule formulation. Methods In an open-label, four-period, single-dose, crossover study, healthy volunteers were randomly assigned to one of two treatment sequences (T-R-T-R and R-T-R-T; T = dronabinol 4.25 mg oral solution and R = dronabinol 5 mg capsule) under fasted conditions, with a minimum 7-day washout period between doses. Analyses were performed on venous blood samples drawn 15 minutes to 48 hours postdose, and dronabinol concentrations were assayed by liquid chromatography–tandem mass spectrometry. Results Fifty-one of 52 individuals had pharmacokinetic data for analysis. The 90% confidence interval of the geometric mean ratio (oral solution/capsule) for dronabinol was within the 80%–125% bioequivalence range for area under the plasma concentration–time curve (AUC) from time zero to last measurable concentration (AUC0–t) and AUC from time zero to infinity (AUC0–∞). Maximum plasma concentration was also bioequivalent for the two dronabinol formulations. Intraindividual variability in AUC0–∞ was >60% lower for dronabinol oral solution 4.25 mg versus dronabinol capsule 5 mg. Plasma dronabinol concentrations were detected within 15 minutes postdose in 100% of patients when receiving oral solution and in <25% of patients when receiving capsules. Conclusion Single-dose dronabinol oral solution 4.25 mg was bioequivalent to dronabinol capsule 5 mg under fasted conditions. Dronabinol oral solution formulation may provide an easy-to-swallow administration option with lower intraindividual variability as well as more rapid absorption versus dronabinol capsules. PMID:27785111

Form-Focused Interaction in Online Tandem Learning

ERIC Educational Resources Information Center

O'Rourke, Breffni

2005-01-01

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

On the Relativistic Correction of Particles Trajectory in Tandem Type Electrostatic Accelerator

NASA Astrophysics Data System (ADS)

Minárik, Stanislav

2015-08-01

A constant potential is applied to the acceleration of the ion-beam in the tandem type electrostatic accelerator. However, not just one voltage is applied, but instead a number of applications can be made in succession by means of the tandem arrangement of high voltage tubes. This number of voltage applications, which is the number of so-called "stages" of a tandem accelerator, may be two, three, or four, depending on the chosen design. Electrostatic field with approximately constant intensity acts on ions in any stage. In general, non-relativistic dynamics is used for the description of the ion transport in tandem accelerator. Energies of accelerated ions are too low and relativistic effects cannot be commonly observed by standard experimental technique. Estimation of possible relativistic correction of ion trajectories is therefore only a matter of calculation. In this note, we briefly present such calculation. Our aim is to show how using the relativistic dynamics modifies the particles trajectory in tandem type accelerator and what parameters determine this modification.

rTANDEM, an R/Bioconductor package for MS/MS protein identification.

PubMed

Fournier, Frédéric; Joly Beauparlant, Charles; Paradis, René; Droit, Arnaud

2014-08-01

rTANDEM is an R/Bioconductor package that interfaces the X!Tandem protein identification algorithm. The package can run the multi-threaded algorithm on proteomic data files directly from R. It also provides functions to convert search parameters and results to/from R as well as functions to manipulate parameters and automate searches. An associated R package, shinyTANDEM, provides a web-based graphical interface to visualize and interpret the results. Together, those two packages form an entry point for a general MS/MS-based proteomic pipeline in R/Bioconductor. rTANDEM and shinyTANDEM are distributed in R/Bioconductor, http://bioconductor.org/packages/release/bioc/. The packages are under open licenses (GPL-3 and Artistice-1.0). frederic.fournier@crchuq.ulaval.ca or arnaud.droit@crchuq.ulaval.ca Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Head, J.; Turner, J.A.

2006-01-01

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable ofmore » splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.« less

An accurate proteomic quantification method: fluorescence labeling absolute quantification (FLAQ) using multidimensional liquid chromatography and tandem mass spectrometry.

PubMed

Liu, Junyan; Liu, Yang; Gao, Mingxia; Zhang, Xiangmin

2012-08-01

A facile proteomic quantification method, fluorescent labeling absolute quantification (FLAQ), was developed. Instead of using MS for quantification, the FLAQ method is a chromatography-based quantification in combination with MS for identification. Multidimensional liquid chromatography (MDLC) with laser-induced fluorescence (LIF) detection with high accuracy and tandem MS system were employed for FLAQ. Several requirements should be met for fluorescent labeling in MS identification: Labeling completeness, minimum side-reactions, simple MS spectra, and no extra tandem MS fragmentations for structure elucidations. A fluorescence dye, 5-iodoacetamidofluorescein, was finally chosen to label proteins on all cysteine residues. The fluorescent dye was compatible with the process of the trypsin digestion and MALDI MS identification. Quantitative labeling was achieved with optimization of reacting conditions. A synthesized peptide and model proteins, BSA (35 cysteines), OVA (five cysteines), were used for verifying the completeness of labeling. Proteins were separated through MDLC and quantified based on fluorescent intensities, followed by MS identification. High accuracy (RSD% < 1.58) and wide linearity of quantification (1-10(5) ) were achieved by LIF detection. The limit of quantitation for the model protein was as low as 0.34 amol. Parts of proteins in human liver proteome were quantified and demonstrated using FLAQ. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient approach to identify different chemical markers between fibrous root and rhizome of Anemarrhena asphodeloides by ultra high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry with multivariate statistical analysis.

PubMed

Wang, Fang-Xu; Yuan, Jian-Chao; Kang, Li-Ping; Pang, Xu; Yan, Ren-Yi; Zhao, Yang; Zhang, Jie; Sun, Xin-Guang; Ma, Bai-Ping

2016-09-10

An ultra high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry approach coupled with multivariate statistical analysis was established and applied to rapidly distinguish the chemical differences between fibrous root and rhizome of Anemarrhena asphodeloides. The datasets of tR-m/z pairs, ion intensity and sample code were processed by principal component analysis and orthogonal partial least squares discriminant analysis. Chemical markers could be identified based on their exact mass data, fragmentation characteristics, and retention times. And the new compounds among chemical markers could be isolated rapidly guided by the ultra high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry and their definitive structures would be further elucidated by NMR spectra. Using this approach, twenty-four markers were identified on line including nine new saponins and five new steroidal saponins of them were obtained in pure form. The study validated this proposed approach as a suitable method for identification of the chemical differences between various medicinal parts in order to expand medicinal parts and increase the utilization rate of resources. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved Reagents for Newborn Screening of Mucopolysaccharidosis Types I, II, and VI by Tandem Mass Spectrometry

PubMed Central

2015-01-01

Tandem mass spectrometry for the multiplex and quantitative analysis of enzyme activities in dried blood spots on newborn screening cards has emerged as a powerful technique for early assessment of lysosomal storage diseases. Here we report the design and process-scale synthesis of substrates for the enzymes α-l-iduronidase, iduronate-2-sulfatase, and N-acetylgalactosamine-4-sulfatase that are used for newborn screening of mucopolysaccharidosis types I, II, and VI. The products contain a bisamide unit that is hypothesized to readily protonate in the gas phase, which improves detection sensitivity by tandem mass spectrometry. The products contain a benzoyl group, which provides a useful site for inexpensive deuteration, thus facilitating the preparation of internal standards for the accurate quantification of enzymatic products. Finally, the reagents are designed with ease of synthesis in mind, thus permitting scale-up preparation to support worldwide newborn screening of lysosomal storage diseases. The new reagents provide the most sensitive assay for the three lysosomal enzymes reported to date as shown by their performance in reactions using dried blood spots as the enzyme source. Also, the ratio of assay signal to that measured in the absence of blood (background) is superior to all previously reported mucopolysaccharidosis types I, II, and VI assays. PMID:24694010

Metabolite identification of the antimalarial naphthoquine using liquid chromatography-tandem high-resolution mass spectrometry in combination with multiple data-mining tools.

PubMed

Sun, Yanhong; Wang, Shuqi; Ji, Jianbo; Zhai, Guangxi; Xing, Jie

2018-06-01

Naphthoquine (NQ) is one of important partner drugs of artemisinin-based combination therapy (ACT), which is recommended for the treatment of uncomplicated Plasmodium falciparum. NQ shows a high cure rate after a single oral administration. It is absorbed quickly (time to peak concentration 2-4 h) and has a long elimination half-life (255 h). However, the metabolism of NQ has not been clarified. In this work, the metabolite profiling of NQ was studied in six liver microsomal incubates (human, cynomolgus monkey, beagle dog, mini pig, rat and CD1 mouse), seven recombinant CYP enzymes (1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4) and rat (plasma, urine, bile and feces) using liquid chromatography tandem high-resolution LTQ-Orbitrap mass spectrometry (HRMS n ) in conjunction with online hydrogen/deuterium exchange. The biological samples were pretreated by protein precipitation and solid-phase extraction. For data processing, multiple data-mining tools were applied in tandem, i.e. background subtraction and followed by mass defect filter. NQ metabolites were characterized by accurate MS/MS fragmentation characteristics, the hydrogen/deuterium exchange data and cLogP simulation. As a result, five phase I metabolites (M1-M5) of NQ were characterized for the first time. Two metabolic pathways were involved: hydroxylation and N-oxidation. This study demonstrates that LC-HRMS n in combination with multiple data-mining tools in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs. Copyright © 2018 John Wiley & Sons, Ltd.

Multivalent binding of formin-binding protein 21 (FBP21)-tandem-WW domains fosters protein recognition in the pre-spliceosome.

PubMed

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

2011-11-04

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

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

PubMed Central

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

2011-01-01

The high abundance of repetitive but nonidentical proline-rich sequences in spliceosomal proteins raises the question of how these known interaction motifs recruit their interacting protein domains. Whereas complex formation of these adaptors with individual motifs has been studied in great detail, little is known about the binding mode of domains arranged in tandem repeats and long proline-rich sequences including multiple motifs. Here we studied the interaction of the two adjacent WW domains of spliceosomal protein FBP21 with several ligands of different lengths and composition to elucidate the hallmarks of multivalent binding for this class of recognition domains. First, we show that many of the proteins that define the cellular proteome interacting with FBP21-WW1-WW2 contain multiple proline-rich motifs. Among these is the newly identified binding partner SF3B4. Fluorescence resonance energy transfer (FRET) analysis reveals the tandem-WW domains of FBP21 to interact with splicing factor 3B4 (SF3B4) in nuclear speckles where splicing takes place. Isothermal titration calorimetry and NMR shows that the tandem arrangement of WW domains and the multivalency of the proline-rich ligands both contribute to affinity enhancement. However, ligand exchange remains fast compared with the NMR time scale. Surprisingly, a N-terminal spin label attached to a bivalent ligand induces NMR line broadening of signals corresponding to both WW domains of the FBP21-WW1-WW2 protein. This suggests that distinct orientations of the ligand contribute to a delocalized and semispecific binding mode that should facilitate search processes within the spliceosome. PMID:21917930

Multiplex detection of protein toxins using MALDI-TOF-TOF tandem mass spectrometry: application in unambiguous toxin detection from bioaerosol.

PubMed

Alam, Syed Imteyaz; Kumar, Bhoj; Kamboj, Dev Vrat

2012-12-04

Protein toxins, such as botulinum neurotoxins (BoNTs), Clostridium perfringens epsilon toxin (ETX), staphylococcal enterotoxin B (SEB), shiga toxin (STX), and plant toxin ricin, are involved in a number of diseases and are considered as potential agents for bioterrorism and warfare. From a bioterrorism and warfare perspective, these agents are likely to cause maximum damage to a civilian or military population through an inhalational route of exposure and aerosol is considered the envisaged mode of delivery. Unambiguous detection of toxin from aerosol is of paramount importance, both for bringing mitigation protocols into operation and for implementation of effective medical countermeasures, in case a "biological cloud" is seen over a population. A multiplex, unambiguous, and qualitative detection of protein toxins is reported here using tandem mass spectrometry with MALDI-TOF-TOF. The methodology involving simple sample processing steps was demonstrated to identify toxins (ETX, Clostridium perfringes phospholipase C, and SEB) from blind spiked samples. The novel directed search approach using a list of unique peptides was used to identify toxins from a complex protein mixture. The bioinformatic analysis of seven protein toxins for elucidation of unique peptides with conservation status across all known sequences provides a high confidence for detecting toxins originating from any geographical location and source organism. Use of tandem MS data with peptide sequence information increases the specificity of the method. A prototype for generation of aerosol using a nebulizer and collection using a cyclone collector was used to provide a proof of concept for unambiguous detection of toxin from aerosol using precursor directed tandem mass spectrometry combined with protein database searching. ETX prototoxin could be detected from aerosol at 0.2 ppb concentration in aerosol.

Software fault tolerance in computer operating systems

NASA Technical Reports Server (NTRS)

Iyer, Ravishankar K.; Lee, Inhwan

1994-01-01

This chapter provides data and analysis of the dependability and fault tolerance for three operating systems: the Tandem/GUARDIAN fault-tolerant system, the VAX/VMS distributed system, and the IBM/MVS system. Based on measurements from these systems, basic software error characteristics are investigated. Fault tolerance in operating systems resulting from the use of process pairs and recovery routines is evaluated. Two levels of models are developed to analyze error and recovery processes inside an operating system and interactions among multiple instances of an operating system running in a distributed environment. The measurements show that the use of process pairs in Tandem systems, which was originally intended for tolerating hardware faults, allows the system to tolerate about 70% of defects in system software that result in processor failures. The loose coupling between processors which results in the backup execution (the processor state and the sequence of events occurring) being different from the original execution is a major reason for the measured software fault tolerance. The IBM/MVS system fault tolerance almost doubles when recovery routines are provided, in comparison to the case in which no recovery routines are available. However, even when recovery routines are provided, there is almost a 50% chance of system failure when critical system jobs are involved.

Determination and quantification of active phenolic compounds in pigeon pea leaves and its medicinal product using liquid chromatography–tandem mass spectrometry.

PubMed

Liu, Wei; Kong, Yu; Zu, Yuangang; Fu, Yujie; Luo, Meng; Zhang, Lin; Li, Ji

2010-07-09

A novel method using liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS) has been optimized and established for the qualitative and quantitative analysis of ten active phenolic compounds originating from the pigeon pea leaves and a medicinal product thereof (Tongluo Shenggu capsules). In the present study, the chromatographic separation was achieved by means of a HiQ Sil C18V reversed-phase column with a mobile phase consisting of methanol and 0.1% formic acid aqueous solution. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the selected reaction monitoring (SRM) analysis was employed for the detection of ten analytes which included six flavonoids, two isoflavonoids and two stilbenes. All calibration curves showed excellent coefficients of determination (r(2) ≥ 0.9937) within the range of tested concentrations. The intra- and inter-day variations were below 5.36% in terms of relative standard deviation (RSD). The recoveries were 95.08-104.98% with RSDs of 2.06-4.26% for spiked samples of pigeon pea leaves. The method developed was a rapid, efficient and accurate LC-MS/MS method for the detection of phenolic compounds, which can be applied for quality control of pigeon pea leaves and related medicinal products.

Simultaneous quantification of polymethoxylated flavones and coumarins in Fructus aurantii and Fructus aurantii immaturus using HPLC-ESI-MS/MS.

PubMed

Chen, Hai-Fang; Zhang, Wu-Gang; Yuan, Jin-Bin; Li, Yan-Gang; Yang, Shi-Lin; Yang, Wu-Liang

2012-02-05

The major lipid-soluble constituents in Fructus aurantii (zhiqiao) and Fructus aurantii immaturus (zhishi) are polymethoxylated flavones (PMFs) and coumarins. In the present study, a high-performance liquid chromatography with electrospray ionization tandem mass spectrometry method was developed to quantify PMFs (nobiletin, tangeretin, 5-hydroxy-6,7,8,4'-tetramethoxyflavone, and natsudaidai) and coumarins (marmin, meranzin hydrate, and auraptene) simultaneously. PMFs and coumarins were detected by electrospray ionization tandem mass spectrometry in positive ion mode and quantified with multiple reaction monitor. Samples were separated on a Diamonsil C₁₈ (150 mm × 4.6 mm, 5 μm) column using acetonitrile and formic acid-water solution as a mobile phase in gradient mode with a flow rate at 0.5 mL/min. All calibration curves showed good linearity (r² > 0.9977) within the test ranges. Variations of the intraday and interday precisions were less than 4.07%. The recoveries of the components were within the range of 95.79%-105.04% and the relative standard deviations were less than 3.82%. The method developed was validated with acceptable accuracy, precision, and extraction recoveries and can be applied for the identification and quantification of four PMFs and three coumarins in citrus herbs. Copyright © 2011 Elsevier B.V. All rights reserved.

Improved liquid chromatography-MS/MS of heparan sulfate oligosaccharides via chip-based pulsed makeup flow.

PubMed

Huang, Yu; Shi, Xiaofeng; Yu, Xiang; Leymarie, Nancy; Staples, Gregory O; Yin, Hongfeng; Killeen, Kevin; Zaia, Joseph

2011-11-01

Microfluidic chip-based hydrophilic interaction chromatography (HILIC) is a useful separation system for liquid chromatography-mass spectrometry (LC-MS) in compositional profiling of heparan sulfate (HS) oligosaccharides; however, ions observed using HILIC LC-MS are low in charge. Tandem MS of HS oligosaccharide ions with low charge results in undesirable losses of SO(3) from precursor ions during collision induced dissociation. One solution is to add metal cations to stabilize sulfate groups. Another is to add a nonvolatile, polar compound such as sulfolane, a molecule known to supercharge proteins, to produce a similar effect for oligosaccharides. We demonstrate use of a novel pulsed makeup flow (MUF) HPLC-chip. The chip enables controlled application of additives during specified chromatographic time windows and thus minimizes the extent to which nonvolatile additives build up in the ion source. The pulsed MUF system was applied to LC-MS/MS of HS oligosaccharides. Metal cations and sulfolane were tested as additives. The most promising results were obtained for sulfolane, for which supercharging of the oligosaccharide ions increased their signal strengths relative to controls. Tandem MS of these supercharged precursor ions showed decreased abundances of product ions from sulfate losses yet more abundant product ions from backbone cleavages.

Quantification of γ-Aminobutyric Acid in Cerebrospinal Fluid Using Liquid Chromatography-Electrospray Tandem Mass Spectrometry.

PubMed

Arning, Erland; Bottiglieri, Teodoro

2016-01-01

We describe a simple stable isotope dilution method for accurate and precise measurement of γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter in human cerebrospinal fluid (CSF) as a clinical diagnostic test. Determination of GABA in CSF (50 μL) was performed utilizing high performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Analysis of free and total GABA requires two individual sample preparations and mass spectrometry analyses. Free GABA in CSF is determined by a 1:2 dilution with internal standard (GABA-D2) and injected directly onto the HPLC-ESI-MS/MS system. Determination of total GABA in CSF requires additional sample preparation in order to hydrolyze all the bound GABA in the sample to the free form. This requires hydrolyzing the sample by boiling in acidic conditions (hydrochloric acid) for 4 h. The sample is then further diluted 1:10 with a 90 % acetonitrile/0.1 % formic acid solution and injected into the HPLC-ESI-MS/MS system. Each assay is quantified using a five-point standard curve and is linear from 6 nM to 1000 nM and 0.63 μM to 80 μM for free and total GABA, respectively.

Multiresidue analysis of sulfonamides, quinolones, and tetracyclines in animal tissues by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Zhiwen; Li, Xiaowei; Ding, Shuangyang; Jiang, Haiyang; Shen, Jianzhong; Xia, Xi

2016-08-01

A multiresidue method for the efficient identification and quantification of 38 compounds from 3 different classes of antibiotics (tetracyclines, sulfonamides, and quinolones) in animal tissues has been developed. The method optimization involved the selection of extraction solutions, comparison of different solid-phase extraction cartridges and different mobile phases. As a result, the samples were extracted with Mcllvaine and phosphate buffers, followed by clean-up step based on solid-phase extraction with Oasis HLB cartridge. All compounds were determined by ultra-high performance liquid chromatography-tandem mass spectrometry, in one single injection with a chromatographic run time of only 9min. The method efficiency was evaluated in 5 tissues including muscle, liver, and kidney, and the mean recoveries ranged from 54% to 102%, with inter-day relative standard deviation lower than 14%. The limits of quantification were between 0.5 and 10μg/kg, which were satisfactory to support future surveillance monitoring. The developed method was applied to the analysis of swine liver and chicken samples from local markets, and sulfamethazine was the most commonly detected compound in the animal samples, with the highest residue level of 998μg/kg. Copyright © 2016 Elsevier Ltd. All rights reserved.

Validated Method for the Quantification of Baclofen in Human Plasma Using Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Nahar, Limon Khatun; Cordero, Rosa Elena; Nutt, David; Lingford-Hughes, Anne; Turton, Samuel; Durant, Claire; Wilson, Sue; Paterson, Sue

2016-03-01

A highly sensitive and fully validated method was developed for the quantification of baclofen in human plasma. After adjusting the pH of the plasma samples using a phosphate buffer solution (pH 4), baclofen was purified using mixed mode (C8/cation exchange) solid-phase extraction (SPE) cartridges. Endogenous water-soluble compounds and lipids were removed from the cartridges before the samples were eluted and concentrated. The samples were analyzed using triple-quadrupole liquid chromatography-tandem mass spectrometry (LC-MS-MS) with triggered dynamic multiple reaction monitoring mode for simultaneous quantification and confirmation. The assay was linear from 25 to 1,000 ng/mL (r(2) > 0.999; n = 6). Intraday (n = 6) and interday (n = 15) imprecisions (% relative standard deviation) were <5%, and the average recovery was 30%. The limit of detection of the method was 5 ng/mL, and the limit of quantification was 25 ng/mL. Plasma samples from healthy male volunteers (n = 9, median age: 22) given two single oral doses of baclofen (10 and 60 mg) on nonconsecutive days were analyzed to demonstrate method applicability. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ultra-trace levels analysis of microcystins and nodularin in surface water by on-line solid-phase extraction with high-performance liquid chromatography tandem mass spectrometry.

PubMed

Balest, Lydia; Murgolo, Sapia; Sciancalepore, Lucia; Montemurro, Patrizia; Abis, Pier Paolo; Pastore, Carlo; Mascolo, Giuseppe

2016-06-01

An on-line solid phase extraction coupled with high-performance liquid chromatography in tandem with mass spectrometry (on-line SPE/HPLC/MS-MS) method for the determination of five microcystins and nodularin in surface waters at submicrogram per liter concentrations has been optimized. Maximum recoveries were achieved by carefully optimizing the extraction sample volume, loading solvent, wash solvent, and pH of the sample. The developed method was also validated according to both UNI EN ISO IEC 17025 and UNICHIM guidelines. Specifically, ten analytical runs were performed at three different concentration levels using a reference mix solution containing the six analytes. The method was applied for monitoring the concentrations of microcystins and nodularin in real surface water during a sampling campaign of 9 months in which the ELISA method was used as standard official method. The results of the two methods were compared showing good agreement when the highest concentration values of MCs were found. Graphical abstract An on-line SPE/HPLC/MS-MS method for the determination of five microcystins and nodularin in surface waters at sub μg L(-1) was optimized and compared with ELISA assay method for real samples.

Simultaneous analysis of different classes of phytohormones in coconut (Cocos nucifera L.) water using high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry after solid-phase extraction.

PubMed

Ma, Zhen; Ge, Liya; Lee, Anna S Y; Yong, Jean Wan Hong; Tan, Swee Ngin; Ong, Eng Shi

2008-03-10

Coconut (Cocos nucifera L.) water, which contains many uncharacterized phytohormones is extensively used as a growth promoting supplement in plant tissue culture. In this paper, a high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of various classes phytohormones, including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), gibberellic acid (GA), zeatin (Z), N(6)-benzyladenine (BA), alpha-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in young coconut water (CW). The analysis was carried out using a reverse-phase HPLC gradient elution, with an aqueous mobile phase (containing 0.1% formic acid, pH adjusted to 3.2 with triethylamine (TEA)) modified by methanol, and solute detection made at 265 nm wavelength. The method was validated for specificity, quantification, accuracy and precision. After preconcentration of putative endogenous phytohormones in CW using C(18) solid-phase extraction (SPE) cartridges, the HPLC method was able to screen for putative endogenous phytohormones present in CW. Finally, the identities of the putative phytohormones present in CW were further confirmed using independent liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with an electrospray ionization (ESI) interface.

Ultra-high-performance liquid chromatography-tandem mass spectrometry measurement of climbazole deposition from hair care products onto artificial skin and human scalp.

PubMed

Chen, Guoqiang; Hoptroff, Michael; Fei, Xiaoqing; Su, Ya; Janssen, Hans-Gerd

2013-11-22

A sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the measurement of climbazole deposition from hair care products onto artificial skin and human scalp. Deuterated climbazole was used as the internal standard. Atmospheric pressure chemical ionization (APCI) in positive mode was applied for the detection of climbazole. For quantification, multiple reaction monitoring (MRM) transition 293.0>69.0 was monitored for climbazole, and MRM transition 296.0>225.1 for the deuterated climbazole. The linear range ran from 4 to 2000 ng mL(-1). The limit of detection (LOD) and the limit of quantification (LOQ) were 1 ng mL(-1) and 4 ng mL(-1), respectively, which enabled quantification of climbazole on artificial skin and human scalp at ppb level (corresponding to 16 ng cm(-2)). For the sampling of climbazole from human scalp the buffer scrub method using a surfactant-modified phosphate buffered saline (PBS) solution was selected based on a performance comparison of tape stripping, the buffer scrub method and solvent extraction in in vitro studies. Using this method, climbazole deposition in in vitro and in vivo studies was successfully quantified. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of hydroxamate siderophores in soil solution using liquid chromatography with mass spectrometry and tandem mass spectrometry with on-line sample preconcentration.

PubMed

Olofsson, Madelen A; Bylund, Dan

2015-10-01

A liquid chromatography with electrospray ionization mass spectrometry method was developed to quantitatively and qualitatively analyze 13 hydroxamate siderophores (ferrichrome, ferrirubin, ferrirhodin, ferrichrysin, ferricrocin, ferrioxamine B, D1 , E and G, neocoprogen I and II, coprogen and triacetylfusarinine C). Samples were preconcentrated on-line by a switch-valve setup prior to analyte separation on a Kinetex C18 column. Gradient elution was performed using a mixture of an ammonium formate buffer and acetonitrile. Total analysis time including column conditioning was 20.5 min. Analytes were fragmented by applying collision-induced dissociation, enabling structural identification by tandem mass spectrometry. Limit of detection values for the selected ion monitoring method ranged from 71 pM to 1.5 nM with corresponding values of two to nine times higher for the multiple reaction monitoring method. The liquid chromatography with mass spectrometry method resulted in a robust and sensitive quantification of hydroxamate siderophores as indicated by retention time stability, linearity, sensitivity, precision and recovery. The analytical error of the methods, assessed through random-order, duplicate analysis of soil samples extracted with a mixture of 10 mM phosphate buffer and methanol, appears negligible in relation to between-sample variations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of flomoxef in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry.

PubMed

Kravtsova, Oxana Yu; Paramonov, Sergey A; Vasilevich, Natalya I; Kazyulkin, Denis N; Vlasova, Ekaterina; Engsig, Michael

2013-12-01

A specific, sensitive, rapid and reproducible method for the determination of flomoxef in human plasma using high-performance liquid chromatography-tandem mass spectrometry was developed and validated. Flomoxef was detected using an electrospay ionization method operated in negative-ion mode. Chromatographic separation was performed in gradient elution mode on a Luna® C18(2) column (3 μM, 20 × 4.0 mm) at a flow rate of 1 mL/min and runtime 3.5 min. The mobile phase consisted of acetonitrile and water containing 0.1% formic acid as additive. Extraction of flomoxef from plasma and precipitation of plasma proteins was performed with acetonitrile with an absolute recovery of 86.4 ± 1.6%. The calibration curve was linear with a correlation coefficient of 0.999 over the concentration range 10-5000 ng/mL and the lower limit of quantification was 10 ng/mL. The intra- and inter-day precisions were <11.8%, while the accuracy ranged from 99.6 to 109.0%. A stability study of flomoxef revealed that it could be successfully analyzed at 4 ºС over 24 h, but it was unstable in solutions at room temperature during short-term storage (4 h) and several freeze-thaw cycles. Copyright © 2013 John Wiley & Sons, Ltd.

Determination of anthelmintic drug residues in milk using ultra high performance liquid chromatography-tandem mass spectrometry with rapid polarity switching.

PubMed

Whelan, Michelle; Kinsella, Brian; Furey, Ambrose; Moloney, Mary; Cantwell, Helen; Lehotay, Steven J; Danaher, Martin

2010-07-02

A new UHPLC-MS/MS (ultra high performance liquid chromatography coupled to tandem mass spectrometry) method was developed and validated to detect 38 anthelmintic drug residues, consisting of benzimidazoles, avermectins and flukicides. A modified QuEChERS-type extraction method was developed with an added concentration step to detect most of the analytes at <1 microg kg(-1) levels in milk. Anthelmintic residues were extracted into acetonitrile using magnesium sulphate and sodium chloride to induce liquid-liquid partitioning followed by dispersive solid phase extraction for cleanup. The extract was concentrated into dimethyl sulphoxide, which was used as a keeper to ensure analytes remain in solution. Using rapid polarity switching in electrospray ionisation, a single injection was capable of detecting both positively and negatively charged ions in a 13 min run time. The method was validated at two levels: the unapproved use level and at the maximum residue level (MRL) according to Commission Decision (CD) 2002/657/EC criteria. The decision limit (CCalpha) of the method was in the range of 0.14-1.9 and 11-123 microg kg(-1) for drugs validated at unapproved and MRL levels, respectively. The performance of the method was successfully verified for benzimidazoles and levamisole by participating in a proficiency study.

76 FR 73681 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Vertical...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... for OMB Review; Comment Request; Vertical Tandem Lifts for Marine Terminals ACTION: Notice. SUMMARY...) sponsored information collection request (ICR) titled, ``Vertical Tandem Lifts for Marine Terminals,'' to....gov . SUPPLEMENTARY INFORMATION: The Vertical Tandem Lifts (VTLs) standards of regulations 29 CFR part...

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

Code of Federal Regulations, 2010 CFR

2010-10-01

...-switched transport services. 69.713 Section 69.713 Telecommunication FEDERAL COMMUNICATIONS COMMISSION..., traffic-sensitive, and tandem-switched transport services. (a) Scope. This paragraph governs requests for...)(2) of this chapter. (3) The traffic-sensitive components of tandem-switched transport services, as...

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

Code of Federal Regulations, 2011 CFR

2011-10-01

...-switched transport services. 69.713 Section 69.713 Telecommunication FEDERAL COMMUNICATIONS COMMISSION..., traffic-sensitive, and tandem-switched transport services. (a) Scope. This paragraph governs requests for...)(2) of this chapter. (3) The traffic-sensitive components of tandem-switched transport services, as...

Analyte stability during the total testing process: studies of vitamins A, D and E by LC-MS/MS.

PubMed

Albahrani, Ali A; Rotarou, Victor; Roche, Peter J; Greaves, Ronda F

2016-10-01

There are limited evidence based studies demonstrating the stability of fat-soluble vitamins (FSV) measured in blood. This study aimed to examine the effects of light, temperature and time on vitamins A, D and E throughout the total testing process. Four experiments were conducted. Three investigated the sample matrix, of whole blood, serum and the extracted sample, against the variables of temperature and light; and the fourth experiment investigated the sample during the extraction process against the variable of light. All samples were analysed via our simultaneous FSV method using liquid chromatography-tandem mass spectrometry technology. The allowable clinical percentage change was calculated based on biological variation and desirable method imprecision for each analyte. The total change limit was ±7.3% for 25-OH-vitamin D3, ±11.8% for retinol and ±10.8% for α-tocopherol. Vitamins D and E were stable in the investigated conditions (concentration changes <4%) in the pre-analytical and analytical stages. Vitamin A showed photosensitivity in times >48 h with concentration changes of -6.8% (blood) and -6.5% (serum), both are within the allowable clinical percentage change. By contrast, the extracted retinol sample demonstrated a concentration change of -18.4% after 48 h of light exposure. However, vitamin A in the serum and extracted solution was stable for one month when stored at -20°C. Blood samples for vitamins D and E analyses can be processed in normal laboratory conditions of lighting and temperature. The required conditions for vitamin A analysis are similar when performed within 48 h. For longer-term storage, serum and vitamin A extracts should be stored at -20°C.

Optimized anion exchange column isolation of zirconium-89 ( 89 Zr) from yttrium cyclotron target: Method development and implementation on an automated fluidic platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Hara, Matthew J.; Murray, Nathaniel J.; Carter, Jennifer C.

Zirconium-89 (89Zr), produced by the (p,n) reaction from naturally monoisotopic yttrium (natY), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new 89Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization. The separation of Zr from dissolved Y metal targets was evaluated using several anion exchange resins. Each resin was evaluated against its ability to quantitatively capturemore » Zr from a load solution that is high in dissolved Y. The most appropriate anion exchange resin for this application was identified, and the separation method was optimized. The method is capable of a high Y decontamination factor (>105) and has been shown to separate Fe, an abundant contaminant in Y foils, from the 89Zr elution fraction. Finally, the performance of the method was evaluated using cyclotron bombarded Y foil targets. The separation method was shown to achieve >95% recovery of the 89Zr present in the foils. The 89Zr eluent, however, was in a chemical matrix not immediately conducive to labeling onto proteins. The main intent of this study was to develop a tandem column 89Zr purification process, wherein the anion exchange column method described here is the first separation in a dual-column purification process.« less

Site specific ligand substitution in cubane-type Mo3FeS(4)(4+) clusters: kinetics and mechanism of reaction and isolation of mixed ligand Cl/SPh complexes.

PubMed

Algarra, Andrés G; Basallote, Manuel G; Fernandez-Trujillo, M J; Llusar, Rosa; Pino-Chamorro, Jose A; Sorribes, Ivan; Vicent, Cristian

2010-04-21

The synthesis, crystal structure and solution characterization of the cubane-type [Mo(3)(FeCl)S(4)(dmpe)(3)Cl(3)] (1) (dmpe = 1,2-bis(dimethylphophane-ethane)) cluster are reported and the ligand substitution processes of chloride by thiophenolate investigated. The kinetics and the intimate mechanism of these substitutions reveal that compound 1 undergoes a number of Fe and Mo site specific ligand substitution reactions in acetonitrile solutions. In particular, PhS(-) coordination at the tetrahedral Fe site proceeds in a single resolved kinetic step whereas such substitutions at the Mo sites proceed more slowly. The effect of the presence of acids in the reaction media is also investigated and reveals that an acid excess hinders substitution reactions both at the Fe and Mo sites; however, an acid-promoted solvolysis of the Fe-Cl bonds is observed. Electrospray ionization (ESI) and tandem (ESI-MS/MS) mass spectrometry allow the identification of all the reaction intermediates proposed on the basis of stopped-flow measurements. The distinctive site specific reactivity made it possible to isolate two new clusters of the Mo(3)FeS(4)(4+) family featuring mixed chlorine/thiophenolate ligands, namely Mo(3)S(4)(FeSPh)(dmpe)(3)Cl(3) (2) and [Mo(3)S(4)(FeSPh)(dmpe)(3)(SPh)(3)] (3). A detailed computational study has also been carried out to understand the details of the mechanism of substitution at the M-Cl (M = Mo and Fe) bonds as well as the solvolysis at the Fe-Cl sites, with particular emphasis on the role of acids on the substitution process. The results of the calculations are in agreement with the experimental observations, thus justifying the non-existence of an accelerating effect of acids on the thiophenolate substitution reaction, which differs from previous proposals for the Fe(4)S(4) and MoFe(3)S(4) clusters and some related compounds.

Tandem Mass Spectrometry of Heparan Sulfate Negative Ions: Sulfate Loss Patterns and Chemical Modification Methods for Improvement of Product Ion Profiles

NASA Astrophysics Data System (ADS)

Shi, Xiaofeng; Huang, Yu; Mao, Yang; Naimy, Hicham; Zaia, Joseph

2012-09-01

Heparan sulfate (HS) is a polysaccharide modified with sulfation, acetylation, and epimerization that enable its binding with protein ligands and regulation of important biological processes. Tandem mass spectrometry has been employed to sequence linear biomolecules e.g., proteins and peptides. However, its application in structural characterization of HS is limited due to the neutral loss of sulfate (SO3) during collisional induced dissociation (CID). In this report, we studied the dissociation patterns of HS disaccharides and demonstrate that the N-sulfate (N-S) bond is especially facile during CID. We identified factors that influence the propensities of such losses from precursor ions and proposed a Free Proton Index (FPI) to help select ions that are able to produce meaningful backbone dissociations. We then investigated the thermodynamics and kinetics of SO3 loss from sulfates that are protonated, deprotonated, and metal-adducted using density functional theory computations. The calculations showed that sulfate loss from a protonated site was much more facile than that from a deprotonated or metal-adducted site. Further, the loss of SO3 from N-sulfate was energetically favored by 3-8 kcal/mol in transition states relative to O-sulfates, making it more prone to this process by a substantial factor. In order to reduce the FPI, representing the number of labile sulfates in HS native chains and oligosaccharides, we developed a series of chemical modifications to selectively replace the N-sulfates of the glucosamine with deuterated acetyl group. These modifications effectively reduced the sulfate density on the HS oligosaccharides and generated considerably more backbone dissociation using on-line LC/tandem MS.

Laser Capture Microdissection and Multiplex-Tandem PCR Analysis of Proximal Tubular Epithelial Cell Signaling in Human Kidney Disease

PubMed Central

Wilkinson, Ray; Wang, Xiangju; Kassianos, Andrew J.; Zuryn, Steven; Roper, Kathrein E.; Osborne, Andrew; Sampangi, Sandeep; Francis, Leo; Raghunath, Vishwas; Healy, Helen

2014-01-01

Interstitial fibrosis, a histological process common to many kidney diseases, is the precursor state to end stage kidney disease, a devastating and costly outcome for the patient and the health system. Fibrosis is historically associated with chronic kidney disease (CKD) but emerging evidence is now linking many forms of acute kidney disease (AKD) with the development of CKD. Indeed, we and others have observed at least some degree of fibrosis in up to 50% of clinically defined cases of AKD. Epithelial cells of the proximal tubule (PTEC) are central in the development of kidney interstitial fibrosis. We combine the novel techniques of laser capture microdissection and multiplex-tandem PCR to identify and quantitate “real time” gene transcription profiles of purified PTEC isolated from human kidney biopsies that describe signaling pathways associated with this pathological fibrotic process. Our results: (i) confirm previous in-vitro and animal model studies; kidney injury molecule-1 is up-regulated in patients with acute tubular injury, inflammation, neutrophil infiltration and a range of chronic disease diagnoses, (ii) provide data to inform treatment; complement component 3 expression correlates with inflammation and acute tubular injury, (iii) identify potential new biomarkers; proline 4-hydroxylase transcription is down-regulated and vimentin is up-regulated across kidney diseases, (iv) describe previously unrecognized feedback mechanisms within PTEC; Smad-3 is down-regulated in many kidney diseases suggesting a possible negative feedback loop for TGF-β in the disease state, whilst tight junction protein-1 is up-regulated in many kidney diseases, suggesting feedback interactions with vimentin expression. These data demonstrate that the combined techniques of laser capture microdissection and multiplex-tandem PCR have the power to study molecular signaling within single cell populations derived from clinically sourced tissue. PMID:24475278

Exploring Site-Specific N-Glycosylation Microheterogeneity of Haptoglobin using Glycopeptide CID Tandem Mass Spectra and Glycan Database Search

PubMed Central

Chandler, Kevin Brown; Pompach, Petr; Goldman, Radoslav

2013-01-01

Glycosylation is a common protein modification with a significant role in many vital cellular processes and human diseases, making the characterization of protein-attached glycan structures important for understanding cell biology and disease processes. Direct analysis of protein N-glycosylation by tandem mass spectrometry of glycopeptides promises site-specific elucidation of N-glycan microheterogeneity, something which detached N-glycan and de-glycosylated peptide analyses cannot provide. However, successful implementation of direct N-glycopeptide analysis by tandem mass spectrometry remains a challenge. In this work, we consider algorithmic techniques for the analysis of LC-MS/MS data acquired from glycopeptide-enriched fractions of enzymatic digests of purified proteins. We implement a computational strategy which takes advantage of the properties of CID fragmentation spectra of N-glycopeptides, matching the MS/MS spectra to peptide-glycan pairs from protein sequences and glycan structure databases. Significantly, we also propose a novel false-discovery-rate estimation technique to estimate and manage the number of false identifications. We use a human glycoprotein standard, haptoglobin, digested with trypsin and GluC, enriched for glycopeptides using HILIC chromatography, and analyzed by LC-MS/MS to demonstrate our algorithmic strategy and evaluate its performance. Our software, GlycoPeptideSearch (GPS), assigned glycopeptide identifications to 246 of the spectra at false-discovery-rate 5.58%, identifying 42 distinct haptoglobin peptide-glycan pairs at each of the four haptoglobin N-linked glycosylation sites. We further demonstrate the effectiveness of this approach by analyzing plasma-derived haptoglobin, identifying 136 N-linked glycopeptide spectra at false-discovery-rate 0.4%, representing 15 distinct glycopeptides on at least three of the four N-linked glycosylation sites. The software, GlycoPeptideSearch, is available for download from http://edwardslab.bmcb.georgetown.edu/GPS. PMID:23829323

Additive impairment of the barrier function and irritation by biogenic amines and sodium lauryl sulphate: a controlled in vivo tandem irritation study.

PubMed

Fluhr, J W; Kelterer, D; Fuchs, S; Kaatz, M; Grieshaber, R; Kleesz, P; Elsner, P

2005-01-01

Biogenic amines are potential irritants e.g. in fish-, meat-, milk- and egg-processing professions like cooks, butchers and bakers. The aim of this study was to test the irritative and barrier-disrupting properties of the biogenic amines ammonium hydroxide (AM), dimethylamine (DMA) and trimethylamine (TMA). A repeated sequential irritation of 30 min twice per day was performed over a total of 4 days (tandem repeated irritation test) on the back of 20 healthy volunteers of both sexes with AM, DMA, TMA and sodium lauryl sulphate (SLS). The epidermal barrier function was assessed with a Tewameter TM 210, stratum corneum surface pH was measured with a Skin-pH-Meter 900, inflammation was assessed with a Chromameter CR-300 on the a* axis for redness and a visual score was recorded. All tested biogenic amines (AM, DMA and TMA) induced a barrier disruption and a pH increase paralleled with a 1-day-delayed onset of inflammatory signs. These effects were further enhanced and accelerated by a sequential application of SLS together with the biogenic amines, and inflammation occurred earlier than with the single compounds. Acetic acid (AA) in contrast did only show mild barrier disruption and no significant inflammatory signs. Our system allowed a ranking of the different compounds in their irritative potential in the tandem irritation with SLS: SLS > NaOH > TMA > AA > AM > DMA. The results are suggestive that in the food-processing industry the simultaneous contact with biogenic amines and harmful detergents like SLS should be minimized. Copyright 2005 S. Karger AG, Basel.

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

USDA-ARS?s Scientific Manuscript database

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

Monitoring Bilingualism: Pedagogical Implications of the Bilingual Tandem Analyser

ERIC Educational Resources Information Center

Schwienhorst, Klaus; Borgia, Alexandre

2006-01-01

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

GENETIC DIVERSITY OF TYPHA LATIFOLIA (TYPHACEAE) AND THE IMPACT OF POLLUTANTS EXAMINED WITH TANDEM-REPETITIVE DNA PROBES

EPA Science Inventory

Genetic diversity at variable-number-tandem-repeat (VNTR) loci was examined in the common cattail, Typha latifolia (Typhaceae), using three synthetic DNA probes composed of tandemly repeated "core" sequences (GACA, GATA, and GCAC). The principal objectives of this investigation w...

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

Code of Federal Regulations, 2010 CFR

2010-10-01

..., geographically averaged on a study-area-wide basis, that the incumbent local exchange carrier experiences based... exchange carrier experiences based on the prior year's annual use. Tandem-switched transport transmission..., geographically averaged on a study-area-wide basis, that the incumbent local exchange carrier experiences based...

Tandem Translation Classroom: A Case Study

ERIC Educational Resources Information Center

Kim, Dohun; Koh, Taejin

2018-01-01

The transition to student-centred learning, advances in teleconferencing tools, and active international student exchange programmes have stimulated tandem learning in many parts of the world. This pedagogical model is based on a mutual language exchange between tandem partners, where each student is a native speaker in the language the…

Performance of a tandem-rotor/tandem-stator conical-flow compressor designed for a pressure ratio of 3

NASA Technical Reports Server (NTRS)

Wood, J. R.; Owen, A. K.; Schumann, L. F.

1982-01-01

A conical-flow compressor stage with a large radius change through the rotor was tested at three values of rotor tip clearance. The stage had a tandem rotor and a tandem stator. Peak efficiency at design speed was 0.774 at a pressure ratio of 2.613. The rotor was tested without the stator, and detailed survey data were obtained for each rotor blade row. Overall peak rotor efficiency was 0.871 at a pressure ratio of 2.952.

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

PubMed

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

2013-08-07

Polymer tandem solar cells with 10.2% power conversion efficiency are demonstrated via stacking two PDTP-DFBT:PC₇₁ BM bulk heterojunctions, connected by MoO₃/PEDOT:PSS/ZnO as an interconnecting layer. The tandem solar cells increase the power conversion efficiency of the PDTP-DFBT:PC₇₁ BM system from 8.1% to 10.2%, successfully demonstrating polymer tandem solar cells with identical sub-cells of double-digit efficiency. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Progress in amorphous silicon based large-area multijunction modules

NASA Astrophysics Data System (ADS)

Carlson, D. E.; Arya, R. R.; Bennett, M.; Chen, L.-F.; Jansen, K.; Li, Y.-M.; Maley, N.; Morris, J.; Newton, J.; Oswald, R. S.; Rajan, K.; Vezzetti, D.; Willing, F.; Yang, L.

1996-01-01

Solarex, a business unit of Amoco/Enron Solar, is scaling up its a-Si:H/a-SiGe:H tandem device technology for the production of 8 ft2 modules. The current R&D effort is focused on improving the performance, reliability and cost-effectiveness of the tandem junction technology by systematically optimizing the materials and interfaces in small-area single- and tandem junction cells. Average initial conversion efficiencies of 8.8% at 85% yield have been obtained in pilot production runs with 4 ft2 tandem modules.

Combination Light

NASA Astrophysics Data System (ADS)

1990-01-01

The Rayovac TANDEM is an advanced technology combination work light and general purpose flashlight that incorporates several NASA technologies. The TANDEM functions as two lights in one. It features a long range spotlight and wide angle floodlight; simple one-hand electrical switching changes the beam from spot to flood. TANDEM developers made particular use of NASA's extensive research in ergonomics in the TANDEM's angled handle, convenient shape and different orientations. The shatterproof, water resistant plastic casing also draws on NASA technology, as does the shape and beam distance of the square diffused flood. TANDEM's heavy duty magnet that permits the light to be affixed to any metal object borrows from NASA research on rare earth magnets that combine strong magnetic capability with low cost. Developers used a NASA-developed ultrasonic welding technique in the light's interior.

Partners in crime: The role of tandem modules in gene transcription.

PubMed

Sharma, Rajal; Zhou, Ming-Ming

2015-09-01

Histones and their modifications play an important role in the regulation of gene transcription. Numerous modifications, such as acetylation, phosphorylation, methylation, ubiquitination, and SUMOylation, have been described. These modifications almost always co-occur and thereby increase the combinatorial complexity of post-translational modification detection. The domains that recognize these histone modifications often occur in tandem in the context of larger proteins and complexes. The presence of multiple modifications can positively or negatively regulate the binding of these tandem domains, influencing downstream cellular function. Alternatively, these tandem domains can have novel functions from their independent parts. Here we summarize structural and functional information known about major tandem domains and their histone binding properties. An understanding of these interactions is key for the development of epigenetic therapy. © 2015 The Protein Society.

NREL's Thermochemical Conversion Facility Video Text Version | Bioenergy |

Science.gov Websites

steady-state. We use a tandem fast pyrolysis reactor and Davison recirculating reactor system to study ex be continually added and withdrawn so we can study catalyst activity and product composition at catalyst. Here we can study the impact of catalyst formulation and processing conditions on bio-oil

Rio De Janeiro to Claremont: Promoting Intercultural Competence through Student-Driven Online Intercultural Exchanges

ERIC Educational Resources Information Center

Aristizábal, Juanita C.; Welch, Patrick McDermott

2017-01-01

This article describes the process by which the authors created a Virtual Learning Community for cultural and linguistic exchange between college students of Portuguese in the United States and undergraduate and graduate students of English in Brazil. In addition to describing the way the so-called tandem model for telecollaboration was adapted to…

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors, part 8

NASA Technical Reports Server (NTRS)

Brent, J. A.; Clemmons, D. R.

1974-01-01

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.

Atmospheric-pressure ionization and fragmentation of peptides by solution-cathode glow discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwartz, Andrew J.; Shelley, Jacob T.; Walton, Courtney L.

Modern “-omics” (e.g., proteomics, glycomics, metabolomics, etc.) analyses rely heavily on electrospray ionization and tandem mass spectrometry to determine the structural identity of target species. Unfortunately, these methods are limited to specialized mass spectrometry instrumentation. Here in this paper, a novel approach is described that enables ionization and controlled, tunable fragmentation of peptides at atmospheric pressure. In the new source, a direct-current plasma is sustained between a tapered metal rod and a flowing sample-containing solution. As the liquid stream contacts the electrical discharge, peptides from the solution are volatilized, ionized, and fragmented. At high discharge currents (e.g., 70 mA), electrospray-likemore » spectra are observed, dominated by singly and doubly protonated molecular ions. At lower currents (35 mA), many peptides exhibit extensive fragmentation, with a-, b-, c-, x-, and y-type ion series present as well as complex fragments, such as d-type ions, not previously observed with atmospheric-pressure dissociation. Though the mechanism of fragmentation is currently unclear, observations indicate it could result from the interaction of peptides with gas-phase radicals or ultraviolet radiation generated within the plasma.« less

Theoretical interpretation of the limiting electric conductivity in ionic solution

NASA Astrophysics Data System (ADS)

Fraenkel, Dan

2017-12-01

The physical essence of the limiting equivalent ionic conductivity in solution, λ0i, has been a continuing challenge over almost a century. Here I briefly present an ab initio theoretical treatment providing (1) a new insight into the nature of λ0i, and (2) a mathematical formula for computing λ0i. In the new treatment, one assumes that any chosen ion i is surrounded by a spherical body of oriented solvent dipoles carrying the charge of the counterion, and the bulk solvent is a continuum with no molecular detail. λ0i is thus the result of the tandem operation, at hydrodynamic equilibrium, of the dipole body's electrophoretic and relaxation forces exerted on the drifting ion. λ0i is found to be proportional to the radius of ion i, and independent of the ionic charge. From experimental λ0i's, the ion radius can be computed as 'electric radius.' An electric ion-radius scale so derived compares well with other ion-size scales. The current theory expresses λ0i using only universal constants and unitary factors of the ionic solution, and it sheds new light on the fundamental nature of ion and charge transport in a polar liquid medium.

Atmospheric-pressure ionization and fragmentation of peptides by solution-cathode glow discharge

DOE PAGES

Schwartz, Andrew J.; Shelley, Jacob T.; Walton, Courtney L.; ...

2016-06-27

Modern “-omics” (e.g., proteomics, glycomics, metabolomics, etc.) analyses rely heavily on electrospray ionization and tandem mass spectrometry to determine the structural identity of target species. Unfortunately, these methods are limited to specialized mass spectrometry instrumentation. Here in this paper, a novel approach is described that enables ionization and controlled, tunable fragmentation of peptides at atmospheric pressure. In the new source, a direct-current plasma is sustained between a tapered metal rod and a flowing sample-containing solution. As the liquid stream contacts the electrical discharge, peptides from the solution are volatilized, ionized, and fragmented. At high discharge currents (e.g., 70 mA), electrospray-likemore » spectra are observed, dominated by singly and doubly protonated molecular ions. At lower currents (35 mA), many peptides exhibit extensive fragmentation, with a-, b-, c-, x-, and y-type ion series present as well as complex fragments, such as d-type ions, not previously observed with atmospheric-pressure dissociation. Though the mechanism of fragmentation is currently unclear, observations indicate it could result from the interaction of peptides with gas-phase radicals or ultraviolet radiation generated within the plasma.« less

Development of C-reactive protein certified reference material NMIJ CRM 6201-b: optimization of a hydrolysis process to improve the accuracy of amino acid analysis.

PubMed

Kato, Megumi; Kinumi, Tomoya; Yoshioka, Mariko; Goto, Mari; Fujii, Shin-Ichiro; Takatsu, Akiko

2015-04-01

To standardize C-reactive protein (CRP) assays, the National Metrology Institute of Japan (NMIJ) has developed a C-reactive protein solution certified reference material, CRM 6201-b, which is intended for use as a primary reference material to enable the SI-traceable measurement of CRP. This study describes the development process of CRM 6201-b. As a candidate material of the CRM, recombinant human CRP solution was selected because of its higher purity and homogeneity than the purified material from human serum. Gel filtration chromatography was used to examine the homogeneity and stability of the present CRM. The total protein concentration of CRP in the present CRM was determined by amino acid analysis coupled to isotope-dilution mass spectrometry (IDMS-AAA). To improve the accuracy of IDMS-AAA, we optimized the hydrolysis process by examining the effect of parameters such as the volume of protein samples taken for hydrolysis, the procedure of sample preparation prior to the hydrolysis, hydrolysis temperature, and hydrolysis time. Under optimized conditions, we conducted two independent approaches in which the following independent hydrolysis and liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) were combined: one was vapor-phase acid hydrolysis (130 °C, 24 h) and hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) method, and the other was microwave-assisted liquid-phase acid hydrolysis (150 °C, 3 h) and pre-column derivatization liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The quantitative values of the two different amino acid analyses were in agreement within their uncertainties. The certified value was the weighted mean of the results of the two methods. Uncertainties from the value-assignment method, between-method variance, homogeneity, long-term stability, and short-term stability were taken into account in evaluating the uncertainty for a certified value. The certified value and the expanded uncertainty (k = 2) of CRM 6201-b are (40.0 ± 1.6) μmol kg(-1).

Enhancement of efficiencies for tandem green phosphorescent organic light-emitting devices with a p-type charge generation layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Byung Soo; Jeon, Young Pyo; Lee, Dae Uk

2014-10-15

The operating voltage of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was improved by 3% over that of the organic light-emitting device with a molybdenum trioxide layer. The maximum brightness of the tandem green phosphorescent organic light-emitting device at 21.9 V was 26,540 cd/m{sup 2}. The dominant peak of the electroluminescence spectra for the devices was related to the fac-tris(2-phenylpyridine) iridium emission. - Highlights: • Tandem OLEDs with CGL were fabricated to enhance their efficiency. • The operating voltage of the tandem OLED with a HAT-CN layer was improved by 3%. • The efficiency and brightnessmore » of the tandem OLED were 13.9 cd/A and 26,540 cd/m{sup 2}. • Efficiency of the OLED with a HAT-CN layer was lower than that with a MoO{sub 3} layer. - Abstract: Tandem green phosphorescent organic light-emitting devices with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile or a molybdenum trioxide charge generation layer were fabricated to enhance their efficiency. Current density–voltage curves showed that the operating voltage of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was improved by 3% over that of the corresponding organic light-emitting device with a molybdenum trioxide layer. The efficiency and the brightness of the tandem green phosphorescent organic light-emitting device were 13.9 cd/A and 26,540 cd/m{sup 2}, respectively. The current efficiency of the tandem green phosphorescent organic light-emitting device with a 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer was lower by 1.1 times compared to that of the corresponding organic light-emitting device with molybdenum trioxide layer due to the decreased charge generation and transport in the 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile layer resulting from triplet–triplet exciton annihilation.« less

Fluoroscopic percutaneous brush cytology, forceps biopsy and both in tandem for diagnosis of malignant biliary obstruction.

PubMed

Boos, Johannes; Yoo, Raphael J; Steinkeler, Jennifer; Ayata, Gamze; Ahmed, Muneeb; Sarwar, Ammar; Weinstein, Jeffrey; Faintuch, Salomao; Brook, Olga R

2018-02-01

To evaluate percutaneous brush cytology, forceps biopsy and a tandem procedure consisting of both, in the diagnosis of malignant biliary obstruction. A retrospective review of consecutive patients who underwent biliary brush cytology and/or forceps biopsy between 01/2010 and 09/2014 was performed. The cytology and pathology results were compared to the composite outcome (including radiological, pathological and clinical data). Cost for tandem procedure compared to brush cytology and forceps biopsy alone was calculated. A total of 232 interventions in 129 patients (70.8 ± 11.0 years) were included. Composite outcome showed malignancy in 94/129 (72.9%) patients. Sensitivity for brush cytology, forceps biopsy and tandem procedure was 40.6% (95% CI 32.6-48.7%), 42.7% (32.4-53.0%) and 55.8% (44.7-66.9%) with 100% specificity, respectively. There were 9/43 (20.9%) additional cancers diagnosed when forceps biopsy was performed in addition to brush cytology, while there were 13/43 (30.2%) more cancers diagnosed when brush cytology was performed in addition to forceps biopsy. Additional costs per additionally diagnosed malignancy if tandem approach is to be utilised in all cases was $704.96. Using brush cytology and forceps biopsy in tandem improves sensitivity compared to brush cytology and forceps biopsy alone in the diagnosis of malignant biliary obstruction. • Tandem procedure improves sensitivity compared to brush cytology and forceps biopsy. • Brush cytology may help to overcome "crush artefacts" from forceps biopsy. • The cost per diagnosed malignancy may warrant tandem procedure in all patients.

Artificial urinary sphincter revision for urethral atrophy: Comparing single cuff downsizing and tandem cuff placement.

PubMed

Linder, Brian J; Viers, Boyd R; Ziegelmann, Matthew J; Rivera, Marcelino E; Elliott, Daniel S

2017-01-01

To compare outcomes for single urethral cuff downsizing versus tandem cuff placement during artificial urinary sphincter (AUS) revision for urethral atrophy. We identified 1778 AUS surgeries performed at our institution from 1990-2014. Of these, 406 were first AUS revisions, including 69 revisions for urethral atrophy. Multiple clinical and surgical variables were evaluated for potential association with device outcomes following revision, including surgical revision strategy (downsizing a single urethral cuff versus placing tandem urethral cuffs). Of the 69 revision surgeries for urethral atrophy at our institution, 56 (82%) were tandem cuff placements, 12 (18%) were single cuff downsizings and one was relocation of a single cuff. When comparing tandem cuff placements and single cuff downsizings, the cohorts were similar with regard to age (p=0.98), body-mass index (p=0.95), prior pelvic radiation exposure (p=0.73) and length of follow-up (p=0.12). Notably, there was no difference in 3-year overall device survival compared between single cuff and tandem cuff revisions (60% versus 76%, p=0.94). Likewise, no significant difference was identified for tandem cuff placement (ref. single cuff) when evaluating the risk of any tertiary surgery (HR 0.95, 95% CI 0.32-4.12, p=0.94) or urethral erosion/device infection following revision (HR 0.79, 95% CI 0.20-5.22, p=0.77). There was no significant difference in overall device survival in patients undergoing single cuff downsizing or tandem cuff placement during AUS revision for urethral atrophy. Copyright® by the International Brazilian Journal of Urology.

Enantioselective behaviour of tetraconazole during strawberry wine-making process.

PubMed

Liu, Na; Pan, Xinglu; Zhang, Shuang; Ji, Mingshan; Zhang, Zhihong

2018-05-01

The fate of tetraconazole enantiomers in strawberries during wine-making process was studied. The residues were determined by ultra-performance convergence chromatography tandem triple quadrupole mass spectrometry after each process steps. Results indicated that there was significant enantioselective dissipation of tetraconazole enantiomers during the fermentation process. And (-)-tetraconazole degraded faster than (+)-tetraconazole. The half-lives of (-)-tetraconazole and (+)-tetraconazole were 3.12, 3.76 days with washing procedure and 3.18, 4.05 days without washing procedure. The processing factors of strawberry wine samples after each step were generally less than 1. In particular, the processing factors of the fermentation process were the lowest. The results could help facilitate more accurate risk assessments of tetraconazole during wine-making process. © 2018 Wiley Periodicals, Inc.

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

ERIC Educational Resources Information Center

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

2012-01-01

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.…

Tandem junction amorphous silicon solar cells

DOEpatents

Hanak, Joseph J.

1981-01-01

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

GENETIC VARIATION IN RED RASPBERRIES (RUBUS IDAEUS L.; ROSACEAE) FROM SITES DIFFERING IN ORGANIC POLLUTANTS COMPARED WITH SYNTHETIC TANDEM REPEAT DNA PROBES

EPA Science Inventory

Two synthetic tandem repetitive DNA probes were used to compare genetic variation at variable-number-tandem-repeat (VNTR) loci among Rubus idaeus L. var. strigosus (Michx.) Maxim. (Rosaceae) individuals sampled at eight sites contaminated by pollutants (N = 39) and eight adjacent...

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

DOEpatents

Hayward, David R.; Buttz, James H.; Shirey, David L.

2002-01-01

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.

21 CFR 862.1055 - Newborn screening test system for amino acids, free carnitine, and acylcarnitines using tandem...

Code of Federal Regulations, 2012 CFR

2012-04-01

... mass spectrometry is a device that consists of stable isotope internal standards, control materials..., free carnitine, and acylcarnitines using tandem mass spectrometry. 862.1055 Section 862.1055 Food and... screening test system for amino acids, free carnitine, and acylcarnitines using tandem mass spectrometry. (a...

21 CFR 862.1055 - Newborn screening test system for amino acids, free carnitine, and acylcarnitines using tandem...

Code of Federal Regulations, 2014 CFR

2014-04-01

... mass spectrometry is a device that consists of stable isotope internal standards, control materials..., free carnitine, and acylcarnitines using tandem mass spectrometry. 862.1055 Section 862.1055 Food and... screening test system for amino acids, free carnitine, and acylcarnitines using tandem mass spectrometry. (a...

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

PubMed

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

2012-01-01

In proteomics, complex mixtures of proteins are separated (usually by chromatography or electrophoresis) and identified by mass spectrometry. We have created 2DE Tandem MS, a computer program designed for use in the biochemistry, proteomics, or bioinformatics classroom. It contains two simulations-2D electrophoresis and tandem mass spectrometry. The two simulations are integrated together and are designed to teach the concept of proteome analysis of prokaryotic and eukaryotic organisms. 2DE-Tandem MS can be used as a freestanding simulation, or in conjunction with a wet lab, to introduce proteomics in the undergraduate classroom. 2DE Tandem MS is a free program available on Sourceforge at https://sourceforge.net/projects/jbf/. It was developed using Java Swing and functions in Mac OSX, Windows, and Linux, ensuring that every student sees a consistent and informative graphical user interface no matter the computer platform they choose. Java must be installed on the host computer to run 2DE Tandem MS. Example classroom exercises are provided in the Supporting Information. Copyright © 2012 Wiley Periodicals, Inc.

Bifacial Si heterojunction-perovskite organic-inorganic tandem to produce highly efficient ( ηT * ˜ 33%) solar cell

NASA Astrophysics Data System (ADS)

Asadpour, Reza; Chavali, Raghu V. K.; Ryyan Khan, M.; Alam, Muhammad A.

2015-06-01

As single junction photovoltaic (PV) technologies, both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively, a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics, however, we find that a traditional series connected tandem design suffers from low J S C due to band-gap mismatch and current matching constraints. Specifically, a traditional tandem cell with state-of-the-art HIT ( η = 24 % ) and perovskite ( η = 20 % ) sub-cells provides only a modest tandem efficiency of η T ˜ 25%. Instead, we demonstrate that a bifacial HIT/perovskite tandem design decouples the optoelectronic constraints and provides an innovative path for extraordinary efficiencies. In the bifacial configuration, the same state-of-the-art sub-cells achieve a normalized output of ηT * = 33%, exceeding the bifacial HIT performance at practical albedo reflections. Unlike the traditional design, this bifacial design is relatively insensitive to perovskite thickness variations, which may translate to simpler manufacture and higher yield.

Stacking multiple connecting functional materials in tandem organic light-emitting diodes

PubMed Central

Zhang, Tao; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

2017-01-01

Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO3 stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm. This spread light emission, caused by an inductive electric field over one of the device unit, limits one’s ability to fabricate high performance tandem devices. To resolve this issue, a new connecting materials stack with a C60 fullerene buffer layer is reported. This new structure permits optimization of the Al metal layer in the connecting stack and thus enables us to fabricate an efficient tandem OLED having a high 155.6 cd/A current efficiency and a low roll-off (or droop) in current efficiency. PMID:28225028

Stacking multiple connecting functional materials in tandem organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Zhang, Tao; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

2017-02-01

Tandem device is an important architecture in fabricating high performance organic light-emitting diodes and organic photovoltaic cells. The key element in making a high performance tandem device is the connecting materials stack, which plays an important role in electric field distribution, charge generation and charge injection. For a tandem organic light-emitting diode (OLED) with a simple Liq/Al/MoO3 stack, we discovered that there is a significant current lateral spreading causing light emission over an extremely large area outside the OLED pixel when the Al thickness exceeds 2 nm. This spread light emission, caused by an inductive electric field over one of the device unit, limits one’s ability to fabricate high performance tandem devices. To resolve this issue, a new connecting materials stack with a C60 fullerene buffer layer is reported. This new structure permits optimization of the Al metal layer in the connecting stack and thus enables us to fabricate an efficient tandem OLED having a high 155.6 cd/A current efficiency and a low roll-off (or droop) in current efficiency.

Controlled human malaria infection trials: How tandems of trust and control construct scientific knowledge.

PubMed

Bijker, Else M; Sauerwein, Robert W; Bijker, Wiebe E

2016-02-01

Controlled human malaria infections are clinical trials in which healthy volunteers are deliberately infected with malaria under controlled conditions. Controlled human malaria infections are complex clinical trials: many different groups and institutions are involved, and several complex technologies are required to function together. This functioning together of technologies, people, and institutions is under special pressure because of potential risks to the volunteers. In this article, the authors use controlled human malaria infections as a strategic research site to study the use of control, the role of trust, and the interactions between trust and control in the construction of scientific knowledge. The authors argue that tandems of trust and control play a central role in the successful execution of clinical trials and the construction of scientific knowledge. More specifically, two aspects of tandems of trust and control will be highlighted: tandems are sites where trust and control coproduce each other, and tandems link the personal, the technical, and the institutional domains. Understanding tandems of trust and control results in setting some agendas for both clinical trial research and science and technology studies.

Intelligent fault diagnosis and failure management of flight control actuation systems

NASA Technical Reports Server (NTRS)

Bonnice, William F.; Baker, Walter

1988-01-01

The real-time fault diagnosis and failure management (FDFM) of current operational and experimental dual tandem aircraft flight control system actuators was investigated. Dual tandem actuators were studied because of the active FDFM capability required to manage the redundancy of these actuators. The FDFM methods used on current dual tandem actuators were determined by examining six specific actuators. The FDFM capability on these six actuators was also evaluated. One approach for improving the FDFM capability on dual tandem actuators may be through the application of artificial intelligence (AI) technology. Existing AI approaches and applications of FDFM were examined and evaluated. Based on the general survey of AI FDFM approaches, the potential role of AI technology for real-time actuator FDFM was determined. Finally, FDFM and maintainability improvements for dual tandem actuators were recommended.

Constructing STR multiplex assays.

PubMed

Butler, John M

2005-01-01

Multiplex polymerase chain reaction (PCR) refers to the simultaneous amplification of multiple regions of deoxyribonucleic acid (DNA) using PCR. Commercial short tandem repeat (STR) assays that can coamplify as many as 16 different loci have become widely used in forensic DNA typing. This chapter will focus on some of the aspects of constructing robust STR multiplex assays, including careful design and quality control of PCR primers. Examples from the development of a cat STR 12plex and a human Y chromosome STR 20plex are used to illustrate the importance of various parts of the protocol. Primer design parameters and Internet-accessible resources are discussed, as are solutions to problems with residual dye artifacts that result from impure primers.

Determination of virginiamycin M1 residue in tissues of swine and chicken by ultra-performance liquid chromatography tandem mass spectrometry.

PubMed

Wang, Xiaoyang; Wang, Mi; Zhang, Keyu; Hou, Ting; Zhang, Lifang; Fei, Chenzong; Xue, Feiqun; Hang, Taijun

2018-06-01

A reliable UPLC-MS/MS method with high sensitivity was developed and validated for the determination of virginiamycin M1 in muscle, fat, liver, and kidney samples of chicken and swine. Analytes were extracted using acetonitrile and extracts were defatted by N-hexane. Chromatographic separation was performed on a BEH C18 liquid chromatography column. The analytes were then detected using triplequadrupole mass spectrometry in positive electrospray ionization and multiple reaction monitoring mode. Calibration plots were constructed using standard working solutions and showed good linearity. Limits of quantification ranged from 2 to 60 ng mL -1 . Copyright © 2018 Elsevier Ltd. All rights reserved.

Antenna analysis using properties of metamaterials

NASA Astrophysics Data System (ADS)

Mitra, Atindra K.; Hu, Colin; Maxwell, Kasandra

2010-04-01

As part of the Student Internship Programs at Wright-Patterson Air Force Base, including the AFRL Wright Scholar Program for High School Students and the AFRL STEP Program, sample results from preliminary investigation and analysis of integrated antenna structures are reported. Investigation of these novel integrated antenna geometries can be interpreted as a continuation of systems analysis under the general topic area of potential integrated apertures for future software radar/radio solutions [1] [2]. Specifically, the categories of novel integrated aperture geometries investigated in this paper include slotted-fractal structures on microstrip rectangular patch antenna models in tandem with the analysis of exotic substrate materials comprised of a type of synthesized electromagnetic structure known as metamaterials [8] - [10].

Diazonium cation-exchanged clay: an efficient, unfrequented route for making clay/polymer nanocomposites.

PubMed

Salmi, Zakaria; Benzarti, Karim; Chehimi, Mohamed M

2013-11-05

We describe a simple, off-the-beaten-path strategy for making clay/polymer nanocomposites through tandem diazonium salt interface chemistry and radical photopolymerization. Prior to photopolymerization, sodium montmorillonite (MMT) was ion exchanged with N,N'-dimethylbenzenediazonium cation (DMA) from the tetrafluoroborate salt precursor. DMA acts as a hydrogen donor for benzophenone in solution; this pair of co-initiators permits us to photopolymerize glycidyl methacrylate (GMA) between the lamellae of the diazonium-modified clay, therefore providing intercalated MMT-PGMA nanocomposites with an onset of exfoliation. This work conclusively provides a new approach for bridging reactive and functional polymers to layered nanomaterials via aryl diazonium salts in a simple, fast, efficient cation-exchange approach.

Mechanistic and Kinetic Study of Singlet O2 Oxidation of Methionine by On-Line Electrospray Ionization Mass Spectrometry.

PubMed

Liu, Fangwei; Lu, Wenchao; Yin, Xunlong; Liu, Jianbo

2016-01-01

We report a reaction apparatus developed to monitor singlet oxygen ((1)O2) reactions in solution using on-line ESI mass spectrometry and spectroscopy measurements. (1)O2 was generated in the gas phase by the reaction of H2O2 with Cl2, detected by its emission at 1270 nm, and bubbled into aqueous solution continuously. (1)O2 concentrations in solution were linearly related to the emission intensities of airborne (1)O2, and their absolute scales were established based on a calibration using 9,10-anthracene dipropionate dianion as an (1)O2 trapping agent. Products from (1)O2 oxidation were monitored by UV-Vis absorption and positive/negative ESI mass spectra, and product structures were elucidated using collision-induced dissociation-tandem mass spectrometry. To suppress electrical discharge in negative ESI of aqueous solution, methanol was added to electrospray via in-spray solution mixing using theta-glass ESI emitters. Capitalizing on this apparatus, the reaction of (1)O2 with methionine was investigated. We have identified methionine oxidation intermediates and products at different pH, and measured reaction rate constants. (1)O2 oxidation of methionine is mediated by persulfoxide in both acidic and basic solutions. Persulfoxide continues to react with another methionine, yielding methionine sulfoxide as end-product albeit with a much lower reaction rate in basic solution. Density functional theory was used to explore reaction potential energy surfaces and establish kinetic models, with solvation effects simulated using the polarized continuum model. Combined with our previous study of gas-phase methionine ions with (1)O2, evolution of methionine oxidation pathways at different ionization states and in different media is described.

Unassigned MS/MS Spectra: Who Am I?

PubMed

Pathan, Mohashin; Samuel, Monisha; Keerthikumar, Shivakumar; Mathivanan, Suresh

2017-01-01

Recent advances in high resolution tandem mass spectrometry (MS) has resulted in the accumulation of high quality data. Paralleled with these advances in instrumentation, bioinformatics software have been developed to analyze such quality datasets. In spite of these advances, data analysis in mass spectrometry still remains critical for protein identification. In addition, the complexity of the generated MS/MS spectra, unpredictable nature of peptide fragmentation, sequence annotation errors, and posttranslational modifications has impeded the protein identification process. In a typical MS data analysis, about 60 % of the MS/MS spectra remains unassigned. While some of these could attribute to the low quality of the MS/MS spectra, a proportion can be classified as high quality. Further analysis may reveal how much of the unassigned MS spectra attribute to search space, sequence annotation errors, mutations, and/or posttranslational modifications. In this chapter, the tools used to identify proteins and ways to assign unassigned tandem MS spectra are discussed.

Evaluation of a Commercial Sandwich Enzyme-Linked Immunosorbent Assay for the Quantification of Beta-Casomorphin 7 in Yogurt Using Solid-Phase Extraction Coupled to Liquid Chromatography-Tandem Mass Spectrometry as the "Gold Standard" Method.

PubMed

Nguyen, Duc Doan; Busetti, Francesco; Johnson, Stuart Keith; Solah, Vicky Ann

2018-03-01

This study investigated beta-casomorphin 7 (BCM7) in yogurt by means of LC-tandem MS (MS/MS) and enzyme-linked immunosorbent assay (ELISA) and use LC-MS/MS as the "gold standard" method to evaluate the applicability of a commercial ELISA. The level of BCM7 in milk obtained from ELISA analysis was much lower than that obtained by LC-MS/MS analysis and trended to increase during fermentation and storage of yogurt. Meanwhile, the results obtained from LC-MS/MS showed that BCM7 degraded during stages of yogurt processing, and its degradation may have been caused by X-prolyl dipeptidyl aminopeptidase activity. As a result, the commercial sandwich ELISA kit was not suitable for the quantification of BCM7 in fermented dairy milk.

SU-D-BRF-05: A Novel System to Provide Real-Time Image-Guidance for Intrauterine Tandem Insertion and Placement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Price, M; Fontenot, J

Purpose: To develop a system that provides real-time image-guidance for intrauterine tandem insertion and placement for brachytherapy. Methods: The conceptualized system consists of an intrauterine tandem with a transparent, lensed tip, a flexible miniature fiber optic scope, light source and interface for CCD coupling. The tandem tip was designed to act as a lens providing a wide field-of-view (FOV) with minimal image distortion and focus length appropriate for the application. The system is designed so that once inserted, the image-guidance component of the system can be removed and brachytherapy can be administered without interfering with source transport or disturbing tandemmore » placement. Proof-of-principle studies were conducted to assess the conceptualized system's (1) lens functionality (clarity, focus and FOV) (2) and ability to visualize the cervical os of a female placed in the lithotomy position. Results: A prototype of this device was constructed using a commercial tandem modified to incorporate a transparent tip that internally coupled with a 1.9mm diameter fiber optic cable. The 900mm-long cable terminated at an interface that provided illumination as well as facilitated visualization of patient anatomy on a computer. The system provided a 23mm FOV with a focal length of 1cm and provided clear visualization of the cervix, cervical fornix and cervical os. The optical components of the system are easily removed without perturbing the position of a tandem placed in a common fixation clamp. Conclusion: Clinicians frequently encounter difficulty inserting an intrauterine tandem through the cervical os, circumventing fibrotic tissue or masses within the uterus, and positioning the tandem without perforating the uterus. To mitigate these challenges, we have designed and conducted proof-of- principle studies to discern the utility of a prototype device that provides real-time image-guidance for intrauterine tandem placement using fiber optic components.« less

Deciphering the Mode of Action of the Processive Polysaccharide Modifying Enzyme Dermatan Sulfate Epimerase 1 by Hydrogen-Deuterium Exchange Mass Spectrometry.

PubMed

Tykesson, Emil; Mao, Yang; Maccarana, Marco; Pu, Yi; Gao, Jinshan; Lin, Cheng; Zaia, Joseph; Westergren-Thorsson, Gunilla; Ellervik, Ulf; Malmström, Lars; Malmström, Anders

2016-02-01

Distinct from template-directed biosynthesis of nucleic acids and proteins, the enzymatic synthesis of heterogeneous polysaccharides is a complex process that is difficult to study using common analytical tools. Therefore, the mode of action and processivity of those enzymes are largely unknown. Dermatan sulfate epimerase 1 (DS-epi1) is the predominant enzyme during the formation of iduronic acid residues in the glycosaminoglycan dermatan sulfate. Using recombinant DS-epi1 as a model enzyme, we describe a tandem mass spectrometry-based method to study the mode of action of polysaccharide processing enzymes. The enzyme action on the substrate was monitored by hydrogen-deuterium exchange mass spectrometry and the sequence information was then fed into mathematical models with two different assumptions of the mode of action for the enzyme: processive reducing end to non-reducing end, and processive non-reducing end to reducing end. Model data was scored by correlation to experimental data and it was found that DS-epi1 attacks its substrate on a random position, followed by a processive mode of modification towards the non-reducing end and that the substrate affinity of the enzyme is negatively affected by each additional epimerization event. It could also be shown that the smallest active substrate was the reducing end uronic acid in a tetrasaccharide and that octasaccharides and longer oligosaccharides were optimal substrates. The method of using tandem mass spectrometry to generate sequence information of the complex enzymatic products in combination with in silico modeling can be potentially applied to study the mode of action of other enzymes involved in polysaccharide biosynthesis.

Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments

NASA Technical Reports Server (NTRS)

Christoffersen, R.; Keller, L. P.

2007-01-01

Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.

A tandem-based compact dual-energy gamma generator.

PubMed

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

2010-02-01

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.

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

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.

Economic competitiveness of III-V on silicon tandem one-sun photovoltaic solar modules in favorable future scenarios

DOE PAGES

Bobela, David C.; Gedvilas, Lynn; Woodhouse, Michael; ...

2016-09-05

Here, tandem modules combining a III-V top cell with a Si bottom cell offer the potential to increase the solar energy conversion efficiency of one-sun photovoltaic modules beyond 25%, while fully utilizing the global investment that has been made in Si photovoltaics manufacturing. At present, the cost of III-V cells is far too high for this approach to be competitive for one-sun terrestrial power applications. We investigated the system-level economic benefits of both GaAs/Si and InGaP/Si tandem modules in favorable future scenarios where the cost of III-V cells is substantially reduced, perhaps to less than the cost of Si cells.more » We found, somewhat unexpectedly, that these tandems can reduce installed system cost only when the area-related balance-of-system cost is high, such as for area-constrained residential rooftop systems in the USA. When area-related balance-of-system cost is lower, such as for utility-scale systems, the tandem module offers no benefit. This is because a system using tandem modules is more expensive than one using single-junction Si modules when III-V cells are expensive, and a system using tandem modules is more expensive than one using single-junction III-V modules when III-V cells are inexpensive.« less

Economic competitiveness of III-V on silicon tandem one-sun photovoltaic solar modules in favorable future scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bobela, David C.; Gedvilas, Lynn; Woodhouse, Michael

Here, tandem modules combining a III-V top cell with a Si bottom cell offer the potential to increase the solar energy conversion efficiency of one-sun photovoltaic modules beyond 25%, while fully utilizing the global investment that has been made in Si photovoltaics manufacturing. At present, the cost of III-V cells is far too high for this approach to be competitive for one-sun terrestrial power applications. We investigated the system-level economic benefits of both GaAs/Si and InGaP/Si tandem modules in favorable future scenarios where the cost of III-V cells is substantially reduced, perhaps to less than the cost of Si cells.more » We found, somewhat unexpectedly, that these tandems can reduce installed system cost only when the area-related balance-of-system cost is high, such as for area-constrained residential rooftop systems in the USA. When area-related balance-of-system cost is lower, such as for utility-scale systems, the tandem module offers no benefit. This is because a system using tandem modules is more expensive than one using single-junction Si modules when III-V cells are expensive, and a system using tandem modules is more expensive than one using single-junction III-V modules when III-V cells are inexpensive.« less

Simple new method for effective concentration of 188Re solutions from alumina-based 188W-188Re generator.

PubMed

Guhlke, S; Beets, A L; Oetjen, K; Mirzadeh, S; Biersack, H J; Knapp, F F

2000-07-01

(188)Re is a useful generator-produced radioisotope currently under evaluation for a variety of therapeutic applications, including bone pain palliation and intravascular radiation therapy. Because the (188)W parent is available only in a relatively low specific activity (<0.15-0.19 GBq/mg) from reactor irradiation of enriched (186)W, relatively large volumes of 0.9% saline (>15 mL) are required for elution of the (188)Re daughter from traditional alumina-based (188)W-(188)Re generators. Because these large bolus volumes result in solutions with a relatively low specific volume activity of (188)Re (<1 GBq/mL for the 18.5-GBq generator), the availability of effective methods for eluent concentration is important. Our new approach is based on the use of 0.3 mol/L ammonium acetate as a representative salt of a weak acid instead of saline for generator elution. After generator elution, the ammonium acetate generator eluent (15-20 mL) is passed through a tandem IC-H Plus cation (Dowex-H)-anion (QMA Light) column system. Exchange of ammonium cations with hydrogen ions on the cation column forms an acetic acid solution containing perrhenate anions from which the macroscopic levels of the acetate anion of the eluent have been effectively removed. Because perrhenic acid is fully dissociated at this pH, the QMA Light column specifically traps the (188)Re-perrhenate, which is subsequently eluted with a low volume (<1 mL) of saline. Concentration ratios greater than 20:1 are readily achieved with this method. A typical clinical-scale generator loaded with 19.2 GBq (188)W was used to validate the approach. Saline elution provided (188)Re in a 75%-80% yield. Although elution with 0.15 mol/L NH4OAc gave lower yields (55%-60%), use of 0.3 mol/L NH4OAc provided yields comparable with those of saline (70%-75%). (188)W parent breakthrough was not detected after passage of the bolus through the tandem concentration system. Bolus volumes of 15-20 mL, which initially contained as much as 11.1-14.8 GBq (188)Re, were readily concentrated to less than 1 mL saline using QMA Light cartridges. The generator was evaluated for more than 3 mo with no decrease in performance. This approach represents a simple, rapid, and effective method using inexpensive disposable components of concentrating solutions of (188)Re for preparation of therapeutic agents.