Through-thickness thermal conductivity enhancement of graphite film/epoxy composite via short duration acidizing modification

Science.gov (United States)

Wang, Han; Wang, Shaokai; Lu, Weibang; Li, Min; Gu, Yizhou; Zhang, Yongyi; Zhang, Zuoguang

2018-06-01

Graphite films have excellent in-plane thermal conductivity but extremely low through-thickness thermal conductivity because of their intrinsic inter-layer spaces. To improve the inter-layer heat transfer of graphite films, we developed a simple interfacial modification with a short duration mixed-acid treatment. The effects of the mixture ratio of sulfuric and nitric acids and treatment time on the through-thickness thermal properties of graphite films were studied. The modification increased the through-thickness thermal conductivity by 27% and 42% for the graphite film and its composite, respectively. X-ray photoelectron spectroscopy, X-ray powder diffraction, and scanning electron microscopy results indicated that the acidification process had two competing effects: the positive contribution made by the enhanced interaction between the graphite layers induced by the functional groups and the negative effect from the destruction of the graphite layers. As a result, an optimal acidification method was found to be sulfuric/nitric acid treatment with a mixture ratio of 3:1 for 15 min. The resultant through-thickness thermal conductivity of the graphite film could be improved to 0.674 W/mK, and the corresponding graphite/epoxy composite shows a through-thickness thermal conductivity of 0.587 W/mK. This method can be directly used for graphite films and their composite fabrication to improve through-thickness thermal conductivity.

Formation process of graphite film on Ni substrate with improved thickness uniformity through precipitation control

Science.gov (United States)

Kim, Seul-Gi; Hu, Qicheng; Nam, Ki-Bong; Kim, Mun Ja; Yoo, Ji-Beom

2018-04-01

Large-scale graphitic thin film with high thickness uniformity needs to be developed for industrial applications. Graphitic films with thicknesses ranging from 3 to 20 nm have rarely been reported, and achieving the thickness uniformity in that range is a challenging task. In this study, a process for growing 20 nm-thick graphite films on Ni with improved thickness uniformity is demonstrated and compared with the conventional growth process. In the film grown by the process, the surface roughness and coverage were improved and no wrinkles were observed. Observations of the film structure reveal the reasons for the improvements and growth mechanisms.

Carbon isotope geothermometry of graphite-bearing marbles from Central Dronning Maud Land, East Antarctica

International Nuclear Information System (INIS)

Wand, U.; Muehle, K.

1988-01-01

In order to estimate the peak metamorphic temperatures in high-grade regional metamorphic marbles from central Dronning Maud Land (East Antarctica), 13 C/ 12 C isotope ratios have been measured for coexisting carbonate and graphite pairs. The δ 13 C values of carbonates (calcite ± dolomite) and graphite vary from -0.1 to +4.6 permill (PDB) and from -3.3 to +1.7 permill, respectively. The isotopic fractionation between carbonate and graphite ranges from 2.9 to 4.0 permill and is similar to the Δ 13 C (carb-gr) values observed in other East Antarctic and non-Antarctic granulite-facies marbles. The metamorphic temperatures calculated using the equation of VALLEY and O'NEIL (1981) for calcite-graphite pairs are predominantly in the range 700 0 - 800 0 C (x n=5 ± s = 730 0 ± 30 0 C) and agree well with metamorphic temperatures derived from mineral chemical studies in this East Antarctic region. (author)

Stable isotope labeling strategy based on coding theory

Energy Technology Data Exchange (ETDEWEB)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori, E-mail: kigawa@riken.jp [RIKEN Quantitative Biology Center (QBiC), Laboratory for Biomolecular Structure and Dynamics (Japan)

2015-10-15

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells.

Stable isotope labeling strategy based on coding theory

International Nuclear Information System (INIS)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori

2015-01-01

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells

Stereoselective synthesis of stable-isotope-labeled amino acids

Energy Technology Data Exchange (ETDEWEB)

Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)

1994-12-01

For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

Stereoselective synthesis of stable-isotope-labeled amino acids

International Nuclear Information System (INIS)

Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III; Lodwig, S.N.

1994-01-01

For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the α-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids

Isotopically labelled vitamin D derivatives and processes for preparing same

International Nuclear Information System (INIS)

Deluca, H.R.; Schnoes, H.K.; Napoli, J.L.; Fivizzani, M.A.

1981-01-01

This invention relates to 26,27-isotopically labelled vitamin D 3 compounds, including radiolabelled vitamin D 3 compounds of high specific activity, methods for their preparation, and intermediates obtained in their synthesis. The method involves reacting an ester of a 26,27-dinor-vitamin D-25-carboxylic acid with an isotopically labelled methyl Grignard reagent or methyl lithium reagent to obtain a 26,27-isotopically labelled compound in which at least some of the H atoms and/or C atoms are heavy isotopes. (author)

Effect of graphite loading on the electrical and mechanical properties of Poly (Ethylene Oxide)/Poly (Vinyl Chloride) polymer films

Science.gov (United States)

Hajar, M. D. S.; Supri, A. G.; Hanif, M. P. M.; Yazid, M. I. M.

2017-10-01

In this study, films consisting of a blend of poly (ethylene oxide)/poly (vinyl chloride) (PEO/PVC) and a conductive filler, graphite were prepared and characterized for their mechanical and electrical properties. Solid polymer blend films based on PEO/PVC (50/50 wt%/wt%) with different graphite loading were prepared by using solution casting technique. Electrical conductivity results discovered the conductivity increased with increasing of filler loading. However, increasing amount of graphite loading led to a decreased in tensile strength and young’s modulus of PEO/PVC/Graphite polymer films. The dispersion of graphite and mechanism of conductive path in the polymer films were also investigated by scanning electron microscopy (SEM). The morphology of the PEO/PVC/Graphite polymer films shows that agglomeration occurred to complete the connection of conductive path, thus improving the conductivity behavior of the polymer films.

Custom synthesis of isotope-labelled Apis mellifera Pheromone

International Nuclear Information System (INIS)

Conanan, Aida P.; Cortes, Nicole Marie A.; Daguno, Cristel Lyn R.; Templonuevo, Jose Angelo A.; Sucgang, Raymond J.

2012-01-01

The object of this study is to determine the optimum conditions for the synthesis of the isotope-labelled isopentyl acetate. Isopentyl acetate is widely used as a raw material in industries, in syntheses, and is utilized as a sex attractant (pheromone) by the bee species, Apis mellifera. The isotope labelling of isopentyl acetate will allow tracking of the fate and movement of the isopentyl acetate in the environment, in chemical transformations, and in biological systems. Esterification by alcoholysis of acetic acid was optimized for the preparation of Carbon-14( 14 C)-labelled isopentyl acetate from 14 C-labelled acetic acid and isoamyl alcohol. The different conditions studied were: (1) The effects of acid catalysis and/or reflux on the incorporation and retention of the isotope label on the product. The efficiency of label incorporation and retention was determined through the beta radioactivity of Carbon 14 in each of the synthetic constructs. Determination of the beta radioactivity concentration of 14 C in the isopentyl acetate product was done using low level liquid scintillation spectrometry. Each of the synthetic products was mixed with Ultima Gold scintillation cocktail in a low potassium glass scintillation vial, and analysed in a low-level Wallac 1414 scintillation counter. The application of catalysis without reflux resulted in the highest yield (35%). The same condition also resulted in the highest abundance of carbon isotope label with 2.40 Bequerels per cubic centimetre, Bq/cc (measurement unit for radioactivity). (author)

Direct laser writing of micro-supercapacitors on hydrated graphite oxide films

Science.gov (United States)

Gao, Wei; Singh, Neelam; Song, Li; Liu, Zheng; Reddy, Arava Leela Mohana; Ci, Lijie; Vajtai, Robert; Zhang, Qing; Wei, Bingqing; Ajayan, Pulickel M.

2011-08-01

Microscale supercapacitors provide an important complement to batteries in a variety of applications, including portable electronics. Although they can be manufactured using a number of printing and lithography techniques, continued improvements in cost, scalability and form factor are required to realize their full potential. Here, we demonstrate the scalable fabrication of a new type of all-carbon, monolithic supercapacitor by laser reduction and patterning of graphite oxide films. We pattern both in-plane and conventional electrodes consisting of reduced graphite oxide with micrometre resolution, between which graphite oxide serves as a solid electrolyte. The substantial amounts of trapped water in the graphite oxide makes it simultaneously a good ionic conductor and an electrical insulator, allowing it to serve as both an electrolyte and an electrode separator with ion transport characteristics similar to that observed for Nafion membranes. The resulting micro-supercapacitor devices show good cyclic stability, and energy storage capacities comparable to existing thin-film supercapacitors.

Protein labelling with stable isotopes: strategies

International Nuclear Information System (INIS)

Lirsac, P.N.; Gilles, N.; Jamin, N.; Toma, F.; Gabrielsen, O.; Boulain, J.C.; Menez, A.

1994-01-01

A protein labelling technique with stable isotopes has been developed at the CEA: a labelled complete medium has been developed, performing as well as the Luria medium, but differing from it because it contains not only free aminated acids and peptides, but also sugars (96% of D-glucopyrannose) and labelled nucleosides. These precursors are produced from a labelled photosynthetic micro-organisms biomass, obtained with micro-algae having incorporated carbon 13, nitrogen 15 and deuterium during their culture. Labelling costs are reduced. 1 fig., 1 tab., 3 refs

Graphene synthesis from graphite/Ni composite films grown by sputtering

International Nuclear Information System (INIS)

Shin, Dong Hee; Yang, Seung Bum; Shin, Dong Yeol; Kim, Chang Oh; Kim, Sung; Choi, Suk Ho; Paek, Sang Hyon

2012-01-01

Graphite/Ni composite films have been deposited on SiO 2 /Si (100) wafers by varying their graphite concentration (n G ) and thickness (t) from 2 to 12 wt% and 40 to 400 nm, respectively, in a RF sputtering system, subsequently annealed at 900 .deg. C for 4 min, and then slowly cooled to room temperature to form graphene layers on Ni surfaces. Several structural-analysis techniques reveal the optimum nG (∼8 wt%) and t (∼160 nm) of the composite films for the synthesis of fewest-layer, defect-minimized graphene. At the annealing temperature, carbon atoms diffuse out from the composite film, followed by their precipitation as graphene on the Ni layer as the carbon solubility limit in Ni is reached during the cooling period. Based on this mechanism, the optimum conditions are explained. Our approach provides an advantage in that the number of layers can be simply tuned by varying n G and t of the composite films.

Custom isotope-labelling of apis mellifera pheromone

International Nuclear Information System (INIS)

Conanan, Aida P.; Cortes, Nicole Marie A.; Daguno, Cristel Lyn R.; Templonuevo, Jose Angelo A.; Sucgang, Raymond J.

2012-01-01

The object of this study is to determine the optimum conditions for the synthesis of isotope-labelled isoamyl acetate. Esterification by alcoholysis of acetic acid was optimized for the preparation of Carbon - 14 ( 14 C)-labelled isopentyl acetate from 14 C-labelled acetic acid and isopentyl alcohol. The optimization procedure defined the effects of catalysis, reflux time, and temperature. The application of catalysis without reflux resulted to the highest yield (40%); the same condition also resulted to the highest abundance of carbon isotope label with 2.40 disintegrations per minute per cubic centimetre, DPM/cc (measurement unit for radioactivity). Determination of the beta radioactivity concentration of 14 C in the isopentyl acetate product was done using low level liquid scintillation spectrometry. Each of the synthetic constructs was mixed with Ultima Gold scintillation cocktail in a glass scintillation vial, and analysed in a low-level Wallac 1414 scintillation counter. Samples were counted for 2 hours in a chamber temperature maintained at 14 degree centegrade. The catalysed reaction without reflux was established to be the most efficient scheme for the radiolabelling. The radiolabelled isoamyl acetate can give way to the synthesis of more complex substances which can be then tracked when they are introduced to a system through the carbon isotope label. (author)

[Progress in stable isotope labeled quantitative proteomics methods].

Science.gov (United States)

Zhou, Yuan; Shan, Yichu; Zhang, Lihua; Zhang, Yukui

2013-06-01

Quantitative proteomics is an important research field in post-genomics era. There are two strategies for proteome quantification: label-free methods and stable isotope labeling methods which have become the most important strategy for quantitative proteomics at present. In the past few years, a number of quantitative methods have been developed, which support the fast development in biology research. In this work, we discuss the progress in the stable isotope labeling methods for quantitative proteomics including relative and absolute quantitative proteomics, and then give our opinions on the outlook of proteome quantification methods.

Pharmaceuticals labelled with stable isotopes

International Nuclear Information System (INIS)

Krumbiegel, P.

1986-11-01

The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

Physical properties of C60 intercalated graphite films

International Nuclear Information System (INIS)

Nakahara, T; Hosomi, N; Taniguchi, J; Suzuki, M; Sato, T; Abe, K; Kuwahara, D; Ishikawa, M; Kato, M; Miura, K

2007-01-01

Recently, Miura and Tsuda have synthesized C 60 intercalated graphite film (C 60 /Gr) and reported that the C 60 /Gr consists of alternating close-packed C 60 monolayers and graphite layers. They also found that its frictional force is minimal up to the loading force of 100 nN using AFM [Miura K and Tsuda D 2005 e-J. Surf. Sci. Nanotech. 3 21] Thus, we have started to study the physical properties of C 60 /Gr and carried out NMR, Raman scattering and specific heat measurements. These results suggest that C 60 in C 60 /Gr rotates at room temperature

Stable isotope dimethyl labelling for quantitative proteomics and beyond

Science.gov (United States)

Hsu, Jue-Liang; Chen, Shu-Hui

2016-01-01

Stable-isotope reductive dimethylation, a cost-effective, simple, robust, reliable and easy-to- multiplex labelling method, is widely applied to quantitative proteomics using liquid chromatography-mass spectrometry. This review focuses on biological applications of stable-isotope dimethyl labelling for a large-scale comparative analysis of protein expression and post-translational modifications based on its unique properties of the labelling chemistry. Some other applications of the labelling method for sample preparation and mass spectrometry-based protein identification and characterization are also summarized. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644970

Electroactive cytochrome P450BM3 cast polyion films on graphite electrodes

International Nuclear Information System (INIS)

Pardo-Jacques, Aurelie; Basseguy, Regine; Bergel, Alain

2006-01-01

Films of electrochemically active cytochrome P450 BM 3 were constructed on graphite electrodes using alternate assembly with polyethyleneimine (PEI). The original layer-by-layer adsorption method was slightly modified here to form so-called 'cast polyion' films. The cast polyion films were elaborated by immobilizing two successive layers of PEI and protein in very large excess with respect to a monolayer, without any intermediate washing step. Following the immobilization steps by SEM showed that uniform films of a few micrometers were deposited on the graphite surface. The electrochemically activity of the immobilized cytP450 was tested with regard to the reduction of oxygen and the one-electron reduction of the heme. Cyclic voltammetry indicated surface concentration of electrochemically active cytP450 around 0.6nmol/cm 2 , which corresponded to 5% of the total amount of protein that was consumed by the immobilisation process. Adapting the procedure to a graphite felt electrode with the view of scaling up porous electrodes for large scale synthesis increased the concentration to 0.9nmol/cm 2 . Cast polyion films may represent a simple technique to immobilize high amount of electrochemically active protein, keeping the advantage of the electrostatic interactions of the regular layer-by-layer method

13C metabolic flux analysis: optimal design of isotopic labeling experiments.

Science.gov (United States)

Antoniewicz, Maciek R

2013-12-01

Measuring fluxes by 13C metabolic flux analysis (13C-MFA) has become a key activity in chemical and pharmaceutical biotechnology. Optimal design of isotopic labeling experiments is of central importance to 13C-MFA as it determines the precision with which fluxes can be estimated. Traditional methods for selecting isotopic tracers and labeling measurements did not fully utilize the power of 13C-MFA. Recently, new approaches were developed for optimal design of isotopic labeling experiments based on parallel labeling experiments and algorithms for rational selection of tracers. In addition, advanced isotopic labeling measurements were developed based on tandem mass spectrometry. Combined, these approaches can dramatically improve the quality of 13C-MFA results with important applications in metabolic engineering and biotechnology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hierarchical structure graphitic-like/MoS2 film as superlubricity material

Science.gov (United States)

Gong, Zhenbin; Jia, Xiaolong; Ma, Wei; Zhang, Bin; Zhang, Junyan

2017-08-01

Friction and wear result in a great amount of energy loss and the invalidation of mechanical parts, thus it is necessary to minimize friction in practical application. In this study, the graphitic-like/MoS2 films with hierarchical structure were synthesized by the combination of pulse current plasma chemical-vapor deposition and medium frequency unbalanced magnetron sputtering in preheated environment. This hierarchical structure composite with multilayer nano sheets endows the films excellent tribological performance, which easily achieves macro superlubricity (friction coefficient ∼0.004) under humid air. Furthermore, it is expected that hierarchical structure of graphitic-like/MoS2 films could match the requirements of large scale, high bear-capacity and wear-resistance of actual working conditions, which could be widely used in the industrial production as a promising superlubricity material.

Micro-orientation control of silicon polymer thin films on graphite surfaces modified by heteroatom doping

Energy Technology Data Exchange (ETDEWEB)

Shimoyama, Iwao, E-mail: shimoyama.iwao@jaea.go.jp [Material Science Research Center, Atomic Energy Agency, Tokai-mura 2-4, Naka-gun, Ibaraki 319-1195 (Japan); Baba, Yuji [Fukushima Administrative Department, Atomic Energy Agency, Tokai-mura 2-4, Naka-gun, Ibaraki 319-1195 (Japan); Hirao, Norie [Material Science Research Center, Atomic Energy Agency, Tokai-mura 2-4, Naka-gun, Ibaraki 319-1195 (Japan)

2017-05-31

Highlights: • Micro-orientation control method for organic polysilane thin films is proposed. • This method utilizes surface modification of graphite using heteroatom doping. • Lying, standing, and random orientations can be freely controlled by this method. • Micro-pattering of a polysilane film with controlled orientations is achieved. - Abstract: Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is applied to study orientation structures of polydimethylsilane (PDMS) films deposited on heteroatom-doped graphite substrates prepared by ion beam doping. The Si K-edge NEXAFS spectra of PDMS show opposite trends of polarization dependence for non irradiated and N{sub 2}{sup +}-irradiated substrates, and show no polarization dependence for an Ar{sup +}-irradiated substrate. Based on a theoretical interpretation of the NEXAFS spectra via first-principles calculations, we clarify that PDMS films have lying, standing, and random orientations on the non irradiated, N{sub 2}{sup +}-irradiated, and Ar{sup +}-irradiated substrates, respectively. Furthermore, photoemission electron microscopy indicates that the orientation of a PDMS film can be controlled with microstructures on the order of μm by separating irradiated and non irradiated areas on the graphite surface. These results suggest that surface modification of graphite using ion beam doping is useful for micro-orientation control of organic thin films.

Synthesis of carbon-13 labelled carbonaceous deposits and their evaluation for potential use as surrogates to better understand the behaviour of the carbon-14-containing deposit present in irradiated PGA graphite

Energy Technology Data Exchange (ETDEWEB)

Payne, L., E-mail: liam.payne@bristol.ac.uk [Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, BS8 1TL (United Kingdom); Walker, S.; Bond, G. [Centre for Materials Science, University of Central Lancashire, PR1 2HE (United Kingdom); Eccles, H. [John Tyndall Institute for Nuclear Research, School of Computing, Engineering and Physical Sciences, University of Central Lancashire, PR1 2HE (United Kingdom); Heard, P.J.; Scott, T.B. [Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, BS8 1TL (United Kingdom); Williams, S.J. [Radioactive Waste Management, B587, Curie Avenue, Harwell Oxford, Didcot, OX11 0RH (United Kingdom)

2016-03-15

The present work has used microwave plasma chemical vapour deposition to generate suitable isotopically labelled carbonaceous deposits on the surface of Pile Grade A graphite for use as surrogates for studying the behaviour of the deposits observed on irradiated graphite extracted from UK Magnox reactors. These deposits have been shown elsewhere to contain an enhanced concentration of {sup 14}C compared to the bulk graphite. A combination of Raman spectroscopy, ion beam milling with scanning electron microscopy and secondary ion mass spectrometry were used to determine topography and internal morphology in the formed deposits. Direct comparison was made against deposits found on irradiated graphite samples trepanned from a Magnox reactor core and showed a good similarity in appearance. This work suggests that the microwave plasma chemical vapour deposition technique is of value in producing simulant carbon deposits, being of sufficiently representative morphology for use in non-radioactive surrogate studies of post-disposal behaviour of {sup 14}C-containing deposits on some irradiated Magnox reactor graphite.

Isotopic measurements (C,N,O) of detonation soot produced from labeled and unlabeled Composition B-3 indicate source of solid carbon residues

Science.gov (United States)

Podlesak, David; Manner, Virginia; Amato, Ronald; Dattelbaum, Dana; Gusavsen, Richard; Huber, Rachel

2017-06-01

Detonation of HE is an exothermic process whereby metastable complex molecules are converted to simple stable molecules such as H2 O, N2, CO, CO2, and solid carbon. The solid carbon contains various allotropes such as detonation nanodiamonds, graphite, and amorphous carbon. It is well known that certain HE formulations such as Composition B (60% RDX, 40% TNT) produce greater amounts of solid carbon than other more oxygen-balanced formulations. To develop a greater understanding of how formulation and environment influence solid carbon formation, we synthesized TNT and RDX with 13 C and 15 N at levels slightly above natural abundance levels. Synthesized RDX and TNT were mixed at a ratio of 60:40 to form Composition B and solid carbon residues were collected from detonations of isotopically-labeled as well as un-labelled Composition B. The raw HE and detonation residues were analyzed isotopically for C, N, O isotopic compositions. We will discuss differences between treatments groups as a function of formulation and environment. LA-UR - 17-21266.

Triethyl orthoformate as a new film-forming electrolytes solvent for lithium-ion batteries with graphite anodes

International Nuclear Information System (INIS)

Wang Lishi; Huang Yudai; Jia Dianzeng

2006-01-01

Triethyl orthoformate (TEOF) as a new solvent used in propylene carbonate (PC)-based electrolytes together with graphitic anodes in lithium-ion batteries has been investigated. It can be observed that TEOF was capable of suppressing the co-intercalation of PC solvated lithium-ions into the graphite layer during the first lithiation process and the irreversible discharge capacity of the first cycle is the smallest when using 1.0 M LiPF 6 in PC and TEOF at solvent ratio of 1:1 as the electrolytes. The CV, FTIR, EIS, SEM results show that the PC-based electrolytes containing the solvent TEOF can generate an effective solid electrolytes interphase (SEI) film during the first cycling process, and the film is probably mainly composed of ROCO 2 Li, ROLi, Li 2 CO 3 , etc. The formation of a stable passivating film on the graphite surface is believed to be the reason for the improved cell performance. All these results show that TEOF possesses a promising performance for use as an effective film-forming electrolytes solvent in lithium-ion batteries with graphitic anodes

Gluconeogenesis from labeled carbon: estimating isotope dilution

International Nuclear Information System (INIS)

Kelleher, J.K.

1986-01-01

To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoA and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA

Isotope labeling strategies for NMR studies of RNA

International Nuclear Information System (INIS)

Lu, Kun; Miyazaki, Yasuyuki; Summers, Michael F.

2010-01-01

The known biological functions of RNA have expanded in recent years and now include gene regulation, maintenance of sub-cellular structure, and catalysis, in addition to propagation of genetic information. As for proteins, RNA function is tightly correlated with structure. Unlike proteins, structural information for larger, biologically functional RNAs is relatively limited. NMR signal degeneracy, relaxation problems, and a paucity of long-range 1 H- 1 H dipolar contacts have limited the utility of traditional NMR approaches. Selective isotope labeling, including nucleotide-specific and segmental labeling strategies, may provide the best opportunities for obtaining structural information by NMR. Here we review methods that have been developed for preparing and purifying isotopically labeled RNAs, as well as NMR strategies that have been employed for signal assignment and structure determination.

Isotopically labelled benzodiazepines

International Nuclear Information System (INIS)

Liebman, A.A.

1987-01-01

This paper reports on the benzodiazepines which are a class of therapeutic agents. Improvements in the analytical methodology in the areas of biochemistry and pharmacology were significant, particularly in the application of chromatographic and spectroscopic techniques. In addition, the discovery and subsequent development of tritium and carbon-14 as an analytical tool in the biological sciences were essentially post-world war II phenomena. Thus, as these new chemical entities were found to be biologically active, they could be prepared in labeled form for metabolic study, biological half-life determination (pharmacokinetics), tissue distribution study, etc. This use of tracer methodology has been liberally applied to the benzodiazepines and also more recently to the study of receptor-ligand interactions, in which tritium, carbon-11 or fluorine-18 isotopes have been used. The history of benzodiazepines as medicinal agents is indeed an interesting one; an integral part of that history is their use in just about every conceivable labeled form

Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite

International Nuclear Information System (INIS)

Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H.

2014-01-01

This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

SURFACE MODIFICATION OF SEMICONDUCTOR THIN FILM OF TiO2 ON GRAPHITE SUBSTRATE BY Cu-ELECTRODEPOSITION

Directory of Open Access Journals (Sweden)

Fitria Rahmawati

2010-06-01

Full Text Available Surface modification of graphite/TiO2 has been done by mean of Cu electrodeposition. This research aims to study the effect of Cu electrodeposition on photocatalytic enhancing of TiO2. Electrodeposition has been done using CuSO4 0,4 M as the electrolyte at controlled current. The XRD pattern of modified TiO2 thin film on graphite substrate exhibited new peaks at 2θ= 43-44o and 2θ= 50-51o that have been identified as Cu with crystal cubic system, face-centered crystal lattice and crystallite size of 26-30 nm. CTABr still remains in the material as impurities. Meanwhile, based on morphological analysis, Cu particles are dissipated in the pore of thin film. Graphite/TiO2/Cu has higher photoconversion efficiency than graphite/TiO2.   Keywords: semiconductor, graphite/TiO2, Cu electrodeposition

Simple, rapid method for the preparation of isotopically labeled formaldehyde

Science.gov (United States)

Hooker, Jacob Matthew [Port Jefferson, NY; Schonberger, Matthias [Mains, DE; Schieferstein, Hanno [Aabergen, DE; Fowler, Joanna S [Bellport, NY

2011-10-04

Isotopically labeled formaldehyde (*C.sup..sctn.H.sub.2O) is prepared from labeled methyl iodide (*C.sup..sctn.H.sub.3I) by reaction with an oxygen nucleophile having a pendant leaving group. The mild and efficient reaction conditions result in good yields of *C.sup..sctn.H.sub.2O with little or no *C isotopic dilution. The simple, efficient production of .sup.11CH.sub.2O is described. The use of the .sup.11CH.sub.2O for the formation of positron emission tomography tracer compounds is described. The reaction can be incorporated into automated equipment available to radiochemistry laboratories. The isotopically labeled formaldehyde can be used in a variety of reactions to provide radiotracer compounds for imaging studies as well as for scintillation counting and autoradiography.

Characterization and relative quantification of phospholipids based on methylation and stable isotopic labeling[S

Science.gov (United States)

Cai, Tanxi; Shu, Qingbo; Liu, Peibin; Niu, Lili; Guo, Xiaojing; Ding, Xiang; Xue, Peng; Xie, Zhensheng; Wang, Jifeng; Zhu, Nali; Wu, Peng; Niu, Lili; Yang, Fuquan

2016-01-01

Phospholipids (PLs), one of the lipid categories, are not only the primary building blocks of cellular membranes, but also can be split to produce products that function as second messengers in signal transduction and play a pivotal role in numerous cellular processes, including cell growth, survival, and motility. Here, we present an integrated novel method that combines a fast and robust TMS-diazomethane-based phosphate derivatization and isotopic labeling strategy, which enables simultaneous profiling and relative quantification of PLs from biological samples. Our results showed that phosphate methylation allows fast and sensitive identification of the six major PL classes, including their lysophospholipid counterparts, under positive ionization mode. The isotopic labeling of endogenous PLs was achieved by deuterated diazomethane, which was generated through acid-catalyzed hydrogen/deuterium (H/D) exchange and methanolysis of TMS-diazomethane during the process of phosphate derivatization. The measured H/D ratios of unlabeled and labeled PLs, which were mixed in known proportions, indicated that the isotopic labeling strategy is capable of providing relative quantitation with adequate accuracy, reproducibility, and a coefficient of variation of 9.1%, on average. This novel method offers unique advantages over existing approaches and presents a powerful tool for research of PL metabolism and signaling. PMID:26733148

Isotope effect study of κ-(BEDT-TTF)2Cu(NCS)2: Labeling in the anion

International Nuclear Information System (INIS)

Kini, A.M.; Wang, H.H.; Schlueter, J.A.

1995-01-01

Since the initial discovery of organic superconductivity in 1979, a large number of organic superconductors have now been synthesized. However, the mechanism of electron-pairing in these novel superconductors has remained largely unresolved. Isotope effect studies constitute an important experimental tool for the investigation of whether or not the electron-pairing mechanism in organic superconductors is phonon-mediated, as in conventional superconductors. Recent isotope effect studies in the authors' laboratory, involving seven different isotopically labeled BEDT-TTF (or ET) derivatives, have demonstrated the following: (1) intramolecular phonon modes involving C double-bond C and Csingle bondS stretching vibrations in the ET donor molecule are not the dominant mediators of electron-pairing, and (2) in κ-(ET) 2 Cu(NCS) 2 , there exist two competing isotope effects--a normal mass effect, i.e., lowering of T c upon isotopic labeling, when the ET molecular mass is increased by concurrent 13 C and 34 S labeling, in addition to an inverse isotope effect upon deuterium labeling in ET. It is of great interest to investigate if there is an isotope effect when the charge-compensating anions, which are also located within the non-conducting layer in the superconducting cation-radical salts, are isotopically labeled. The existence of an isotope effect when the anions are labeled would be indicative of electron-pairing with the mediation of vibrational frequencies associated with the anions. In this paper, the authors present the results of the first isotope effect study in which isotopic labeling in the anion portion of κ-(ET) 2 Cu(NCS) 2 is carried out. The authors find no isotope effect when the carbon and nitrogen atoms of the thiocyanate groups in the anion are replaced with 13 C and 15 N isotopes

Isotopic labelling with carbon-14 and tritium

International Nuclear Information System (INIS)

Evans, E.A.

1980-01-01

In this paper general methods of isotopic labelling with 14 C and with 3 H are briefly reviewed with special attention to examples of compounds likely to be of wide interest in biological research. (author)

The synthesis of a tritium, carbon-14, and stable isotope-labeled cathepsin C inhibitors.

Science.gov (United States)

Allen, Paul; Bragg, Ryan A; Caffrey, Moya; Ericsson, Cecilia; Hickey, Michael J; Kingston, Lee P; Elmore, Charles S

2017-02-01

As part of a medicinal chemistry program aimed at developing a highly potent and selective cathepsin C inhibitor, tritium, carbon-14, and stable isotope-labeled materials were required. The synthesis of tritium-labeled methanesulfonate 5 was achieved via catalytic tritiolysis of a chloro precursor, albeit at a low radiochemical purity of 67%. Tritium-labeled AZD5248 was prepared via a 3-stage synthesis, utilizing amide-directed hydrogen isotope exchange. Carbon-14 and stable isotope-labeled AZD5248 were successfully prepared through modifications of the medicinal chemistry synthetic route, enabling the use of available labeled intermediates. Copyright © 2016 John Wiley & Sons, Ltd.

NMR studies of isotopically labeled RNA

Energy Technology Data Exchange (ETDEWEB)

Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

1994-12-01

In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

Advances in stable isotope assisted labeling strategies with information science.

Science.gov (United States)

Kigawa, Takanori

2017-08-15

Stable-isotope (SI) labeling of proteins is an essential technique to investigate their structures, interactions or dynamics by nuclear magnetic resonance (NMR) spectroscopy. The assignment of the main-chain signals, which is the fundamental first step in these analyses, is usually achieved by a sequential assignment method based on triple resonance experiments. Independently of the triple resonance experiment-based sequential assignment, amino acid-selective SI labeling is beneficial for discriminating the amino acid type of each signal; therefore, it is especially useful for the signal assignment of difficult targets. Various combinatorial selective labeling schemes have been developed as more sophisticated labeling strategies. In these strategies, amino acids are represented by combinations of SI labeled samples, rather than simply assigning one amino acid to one SI labeled sample as in the case of conventional amino acid-selective labeling. These strategies have proven to be useful for NMR analyses of difficult proteins, such as those in large complex systems, in living cells, attached or integrated into membranes, or with poor solubility. In this review, recent advances in stable isotope assisted labeling strategies will be discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis of 14C-labeled and stable isotope-labeled CGS 16617

International Nuclear Information System (INIS)

Chaudhuri, N.K.; Markus, B.; Sung Mingsang

1988-01-01

The synthesis of a 14 C-labeled and two stable isotope-labeled analogs of CGS 16617 is described. The synthetic method involved the preparation of tetrahydro-3-bromo-1-benzazepin-2-one, labeled with a 14 C or four deuterium atoms, followed by introduction of two side chains at 1- and 3-positions. The labeled bromobenzazepinones were prepared by Beckmann rearrangement of bromo-oximes of α-tetralones, obtained by cyclization of labeled benzenebutanoic acids. The 14 C-labeled acid was prepared by hydrolysis of the nitrile, prepared by reaction of 3-bromopropylbenzene and K 14 CN. The tetradeutero acid was prepared from ethyl phenylpropynoate by catalytic reduction of the triple bond with deuterium gas, followed by reduction of the deuterated ester with lithium aluminium hydride and conversion of the resulting alcohol into the carboxylic acid. The acetic acid side chain was introduced by N-alkylation with ethyl bromoacetate or ethyl bromoacetate-1, 2- 13 C 2 followed by hydrolysis, and the L-lysine side chain, by reaction with L-(-)-3-amino-ε-caprolactam followed by hydrolysis of the caprolactam ring. (author)

Production of isotopically labeled heterologous proteins in non-E. coli prokaryotic and eukaryotic cells

International Nuclear Information System (INIS)

Takahashi, Hideo; Shimada, Ichio

2010-01-01

The preparation of stable isotope-labeled proteins is necessary for the application of a wide variety of NMR methods, to study the structures and dynamics of proteins and protein complexes. The E. coli expression system is generally used for the production of isotope-labeled proteins, because of the advantages of ease of handling, rapid growth, high-level protein production, and low cost for isotope-labeling. However, many eukaryotic proteins are not functionally expressed in E. coli, due to problems related to disulfide bond formation, post-translational modifications, and folding. In such cases, other expression systems are required for producing proteins for biomolecular NMR analyses. In this paper, we review the recent advances in expression systems for isotopically labeled heterologous proteins, utilizing non-E. coli prokaryotic and eukaryotic cells.

Stable isotopic labeling-based quantitative targeted glycomics (i-QTaG).

Science.gov (United States)

Kim, Kyoung-Jin; Kim, Yoon-Woo; Kim, Yun-Gon; Park, Hae-Min; Jin, Jang Mi; Hwan Kim, Young; Yang, Yung-Hun; Kyu Lee, Jun; Chung, Junho; Lee, Sun-Gu; Saghatelian, Alan

2015-01-01

Mass spectrometry (MS) analysis combined with stable isotopic labeling is a promising method for the relative quantification of aberrant glycosylation in diseases and disorders. We developed a stable isotopic labeling-based quantitative targeted glycomics (i-QTaG) technique for the comparative and quantitative analysis of total N-glycans using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We established the analytical procedure with the chemical derivatizations (i.e., sialic acid neutralization and stable isotopic labeling) of N-glycans using a model glycoprotein (bovine fetuin). Moreover, the i-QTaG using MALDI-TOF MS was evaluated with various molar ratios (1:1, 1:2, 1:5) of (13) C6 /(12) C6 -2-aminobenzoic acid-labeled glycans from normal human serum. Finally, this method was applied to direct comparison of the total N-glycan profiles between normal human sera (n = 8) and prostate cancer patient sera (n = 17). The intensities of the N-glycan peaks from i-QTaG method showed a good linearity (R(2) > 0.99) with the amount of the bovine fetuin glycoproteins. The ratios of relative intensity between the isotopically 2-AA labeled N-glycans were close to the theoretical molar ratios (1:1, 1:2, 1:5). We also demonstrated that the up-regulation of the Lewis antigen (~82%) in sera from prostate cancer patients. In this proof-of-concept study, we demonstrated that the i-QTaG method, which enables to achieve a reliable comparative quantitation of total N-glycans via MALDI-TOF MS analysis, has the potential to diagnose and monitor alterations in glycosylation associated with disease states or biotherapeutics. © 2015 American Institute of Chemical Engineers.

Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation

International Nuclear Information System (INIS)

Schoeller, D.A.; Leitch, C.A.; Brown, C.

1986-01-01

The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO 2 excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37 0 C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O 2 and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO 2 production

Preparation of radioactive labelled compounds. Pt. 2. 82Br labelled organic bromine compounds by isotopic exchange

International Nuclear Information System (INIS)

Otto, R.

1988-05-01

Studies on isotopic exchange between organic bromine compounds and 82 Br labelled dioxane dibromide in the presence of AlCl 3 are described. The results obtained enable to develop a simple and quick preparation method for the labelling with 82 Br [fr

Availability of phosphorus in cow slurry using isotopic labelling technique

International Nuclear Information System (INIS)

Pongsakul, P.; Bertelsen, F.; Gissel-Nielsen, G.

1988-01-01

A pot experiment was conducted to evaluate the influence of cow slurry on P uptake by corn and to estimate the readily available P in the slurry by using an isotopic labelling techique. Water-soluble P in soil was increased and isotopic equilibrium of available P was attained after labelled slurry was mixed thoroughly throughout the soil. Labelled slurry applied at planting increased the P uptake by corn, whereas the same amount applied one week before harvest did not affect the P uptake. It was estimated that 46-54% of the total P uptake in plants is derived from the slurry. The readily available P (the L-value) in the slurry was at least 26 mg/kg which equals 3.7% of the total P. (author)

Research on Lessening of Bonding Effects Between the Metallic and Non-Metallic Surfaces Through the Graphite Films Deposited with Pulsed Electrical Discharges Process

Science.gov (United States)

Marin, L.; Topala, P.

2017-06-01

The paper presents the results of experimental research on the physics of natural graphite film formation, the establishment of chemical composition and functional properties of the graphite films, formed on metal surfaces, as a result of the action of plasma in the air environment, at a normal pressure, under the electrical discharge in impulse conditions (EDI). The researchings were performed in the frame of doctoral thesis “Research on lessening of the bonding effects between the metallic and nonmetallic surfaces through the graphite films” and aimed to identify the phenomena that occur at the interface metal/ film of graphite, and to identify also the technological applications that it may have the surface treatment for submitting the films of graphite on metallic surfaces achieved through an innovative process of electrical pulsed discharges. After the research works from the PhD theme above mentioned, a number of interesting properties of graphite pellicle have been identified ie reducing of metal surface polarity. This led to drastic decreases for the values of adhesion when bonding of metal surfaces was performed using a structural polyurethane adhesive designed by ICECHIM. Following the thermo-gravimetric analysis, performed of the graphite film obtained by process of electrical pulsed discharges, have been also discovered other interesting properties for this, ie reversible mass additions at specific values of the working temperature Chemical and scanning electron microscopy analysis have revealed that on the metallic surface subjected to electrical pulsed discharges process, outside the graphite film, it is also obtained a series of spatial formation composed of carbon atoms fullerenes type which are responsible for the phenomenon of addition of mass.

Large-area graphene films by simple solution casting of edge-selectively functionalized graphite.

Science.gov (United States)

Bae, Seo-Yoon; Jeon, In-Yup; Yang, Jieun; Park, Noejung; Shin, Hyeon Suk; Park, Sungjin; Ruoff, Rodney S; Dai, Liming; Baek, Jong-Beom

2011-06-28

We report edge-selective functionalization of graphite (EFG) for the production of large-area uniform graphene films by simply solution-casting EFG dispersions in dichloromethane on silicon oxide substrates, followed by annealing. The resultant graphene films show ambipolar transport properties with sheet resistances of 0.52-3.11 kΩ/sq at 63-90% optical transmittance. EFG allows solution processing methods for the scalable production of electrically conductive, optically transparent, and mechanically robust flexible graphene films for use in practice.

Escherichia coli cell-free protein synthesis and isotope labeling of mammalian proteins.

Science.gov (United States)

Terada, Takaho; Yokoyama, Shigeyuki

2015-01-01

This chapter describes the cell-free protein synthesis method, using an Escherichia coli cell extract. This is a cost-effective method for milligram-scale protein production and is particularly useful for the production of mammalian proteins, protein complexes, and membrane proteins that are difficult to synthesize by recombinant expression methods, using E. coli and eukaryotic cells. By adjusting the conditions of the cell-free method, zinc-binding proteins, disulfide-bonded proteins, ligand-bound proteins, etc., may also be produced. Stable isotope labeling of proteins can be accomplished by the cell-free method, simply by using stable isotope-labeled amino acid(s) in the cell-free reaction. Moreover, the cell-free protein synthesis method facilitates the avoidance of stable isotope scrambling and dilution over the recombinant expression methods and is therefore advantageous for amino acid-selective stable isotope labeling. Site-specific stable isotope labeling is also possible with a tRNA molecule specific to the UAG codon. By the cell-free protein synthesis method, coupled transcription-translation is performed from a plasmid vector or a PCR-amplified DNA fragment encoding the protein. A milligram quantity of protein can be produced with a milliliter-scale reaction solution in the dialysis mode. More than a thousand solution structures have been determined by NMR spectroscopy for uniformly labeled samples of human and mouse functional domain proteins, produced by the cell-free method. Here, we describe the practical aspects of mammalian protein production by the cell-free method for NMR spectroscopy. © 2015 Elsevier Inc. All rights reserved.

Effect of an electrolyte salt dissolving in polysiloxane-based electrolyte on passive film formation on a graphite electrode

Science.gov (United States)

Nakahara, Hiroshi; Nutt, Steven

Electrochemical impedance spectroscopy (EIS) was performed during the first charge of a graphite/lithium metal test cell to determine the effect of an electrolyte salt on passive film formation in a polysiloxane-based electrolyte. The graphite electrode was separated from the lithium metal electrode by a porous polyethylene membrane immersed in a polysiloxane-based electrolyte with the dissolved lithium bis(oxalato) borate (LiBOB) or lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). In case of LiTFSI, the conductivity of system decreased at 1.2 V. In contrast, for the case of LiBOB, the conductivity decreased at 1.7 V. The magnitudes of charge transfer resistance and film resistance for LiTFSI were smaller than that for LiBOB. Passive films on highly oriented pyrolytic graphite (HOPG) after charging (lithiating) in polysiloxane-based electrolyte were inspected microscopically. Gel-like film and island-like films were observed for LiBOB [H. Nakahara, A. Masias, S.Y. Yoon, T. Koike, K. Takeya, Proceedings of the 41st Power Sources Conference, vol. 165, Philadelphia, June 14-17, 2004; H. Nakahara, S.Y. Yoon, T. Piao, S. Nutt, F. Mansfeld, J. Power Sources, in press; H. Nakahara, S.Y. Yoon, S. Nutt, J. Power Sources, in press]. However, for LiTFSI, there was sludge accumulation on the HOPG surface. Compositional analysis revealed the presence of silicon on both HOPG specimens with LiBOB and with LiTFSI. The electrolyte salt dissolved in the polysiloxane-based electrolyte changed the electrochemical and morphological nature of passive films on graphite electrode.

Mechanistic Insights into Catalytic Ethanol Steam Reforming Using Isotope-Labeled Reactants.

Science.gov (United States)

Crowley, Stephen; Castaldi, Marco J

2016-08-26

The low-temperature ethanol steam reforming (ESR) reaction mechanism over a supported Rh/Pt catalyst has been investigated using isotope-labeled EtOH and H2 O. Through strategic isotope labeling, all nonhydrogen atoms were distinct from one another, and allowed an unprecedented level of understanding of the dominant reaction pathways. All combinations of isotope- and non-isotope-labeled atoms were detected in the products, thus there are multiple pathways involved in H2 , CO, CO2 , CH4 , C2 H4 , and C2 H6 product formation. Both the recombination of C species on the surface of the catalyst and preservation of the C-C bond within ethanol are responsible for C2 product formation. Ethylene is not detected until conversion drops below 100 % at t=1.25 h. Also, quantitatively, 57 % of the observed ethylene is formed directly through ethanol dehydration. Finally there is clear evidence to show that oxygen in the SiO2 -ZrO2 support constitutes 10 % of the CO formed during the reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of 15N isotope labeled alanine

International Nuclear Information System (INIS)

Oliveira, Claudineia R. de; Bendassolli, Jose Albertino; Sant'Ana, Carlos Roberto; Tagliassachi, Romulo Barbieri; Maximo, Everaldo; Prestes, Clelber Vieira

2005-01-01

The application of light chemical elements and their stable isotopes in biological studies have been increased over the last years. The use of 15 N labeled amino acids is an important tool for elucidation of peptides structures. This paper describe a method for the synthesis of 15 N isotope labeled alanine at lower costs than international ones, as well as the details of the recovery system of the nitrogen residues. In the present work an amination of α-haloacids, with the bromopropionic carboxylic acid and labeled aqua ammonia ( 15 NH 3 aq) was carried out. In order to avoid eventually losses of 15 NH 3 , special cares were adopted, since the production cost is high. Although the acquisition cost of the 13 N (radioactive) labeled compounds is lower, the obtained stable tracer will allow the accomplishment of important studies of the nitrogen cycling in living things, less occupational and environment hazards, and the time limitation problems in field studies. The tests took place in triplicates with NH 3 (aq) being employed. With the establishment of the system for 15 NH 3 recovery, an average of 94 % of the ammonia employed in the synthesis process was recovered. The purity of the amino acid was state determined by TLC (Thin Layer Chromatography) and HPLC (High-Performance Liquid Chromatography) with a fluorescence detector. The Rf and the retention time of the synthesized sample were similar the sigma standard. Finally, regarding the established conditions, it was possible to obtain the alanine with a production cost about 40 % lower than the international price. (author)

Film thickness determining method of the silicon isotope superlattices by SIMS

International Nuclear Information System (INIS)

Takano, Akio; Shimizu, Yasuo; Itoh, Kohei M.

2008-01-01

It is becoming important to evaluate silicon self-diffusion with progress of a silicon semiconductor industry. In order to evaluate the self-diffusion of silicon, silicon isotope superlattices (SLs) is the only marker. For this reason, it is important to correctly evaluate a film thickness and a depth distribution of isotope SLs by secondary ion mass spectrometry (SIMS). As for film thickness, it is difficult to estimate the thicknesses correctly if the cycles of SLs are short. In this work, first, we report the determination of the film thickness for short-period SLs using mixing roughness-information (MRI) analysis to SIMS profile. Next, the uncertainty of the conventional method to determine the film thicknesses of SLs is determined. It was found that the conventional methods cannot correctly determine film thickness of short-period-isotope SLs where film thickness differs for every layer

Subcellular SIMS imaging of isotopically labeled amino acids in cryogenically prepared cells

International Nuclear Information System (INIS)

Chandra, Subhash

2004-01-01

Ion microscopy is a potentially powerful technique for localization of isotopically labeled molecules. In this study, L-arginine and phenylalanine amino acids labeled with stable isotopes 13 C and 15 N were localized in cultured cells with the ion microscope at 500 nm spatial resolution. Cells were exposed to the labeled amino acids and cryogenically prepared. SIMS analyses were made in fractured freeze-dried cells. A dynamic distribution was observed from labeled arginine-treated LLC-PK 1 kidney cells at mass 28 ( 13 C 15 N) in negative secondaries, revealing cell-to-cell heterogeneity and preferential accumulation of the amino acid (or its metabolite) in the nucleus and nucleolus of some cells. The smaller nucleolus inside the nucleus was clearly resolved in SIMS images and confirmed by correlative light microscopy. The distribution of labeled phenylalanine contrasted with arginine as it was rather homogeneously distributed in T98G human glioblastoma cells. Images of 39 K, 23 Na and 40 Ca were also recorded to confirm the reliability of sample preparation and authenticity of the observed amino acid distributions. These observations indicate that SIMS techniques can provide a valuable technology for subcellular localization of nitrogen-containing molecules in proteomics since nitrogen does not have a radionuclide tracer isotope. Amino acids labeled with stable isotopes can be used as tracers for studying their transport and metabolism in distinct subcellular compartments with SIMS. Further studies of phenylalanine uptake in human glioblastoma cells may have special significance in boron neutron capture therapy (BNCT) as a boron analogue of phenylalanine, boronophenylalanine is a clinically approved compound for the treatment of brain tumors

Subcellular SIMS imaging of isotopically labeled amino acids in cryogenically prepared cells

Energy Technology Data Exchange (ETDEWEB)

Chandra, Subhash

2004-06-15

Ion microscopy is a potentially powerful technique for localization of isotopically labeled molecules. In this study, L-arginine and phenylalanine amino acids labeled with stable isotopes {sup 13}C and {sup 15}N were localized in cultured cells with the ion microscope at 500 nm spatial resolution. Cells were exposed to the labeled amino acids and cryogenically prepared. SIMS analyses were made in fractured freeze-dried cells. A dynamic distribution was observed from labeled arginine-treated LLC-PK{sub 1} kidney cells at mass 28 ({sup 13}C{sup 15}N) in negative secondaries, revealing cell-to-cell heterogeneity and preferential accumulation of the amino acid (or its metabolite) in the nucleus and nucleolus of some cells. The smaller nucleolus inside the nucleus was clearly resolved in SIMS images and confirmed by correlative light microscopy. The distribution of labeled phenylalanine contrasted with arginine as it was rather homogeneously distributed in T98G human glioblastoma cells. Images of {sup 39}K, {sup 23}Na and {sup 40}Ca were also recorded to confirm the reliability of sample preparation and authenticity of the observed amino acid distributions. These observations indicate that SIMS techniques can provide a valuable technology for subcellular localization of nitrogen-containing molecules in proteomics since nitrogen does not have a radionuclide tracer isotope. Amino acids labeled with stable isotopes can be used as tracers for studying their transport and metabolism in distinct subcellular compartments with SIMS. Further studies of phenylalanine uptake in human glioblastoma cells may have special significance in boron neutron capture therapy (BNCT) as a boron analogue of phenylalanine, boronophenylalanine is a clinically approved compound for the treatment of brain tumors.

Graphite in Science and Nuclear Technique

OpenAIRE

Zhmurikov, E. I.; Bubnenkov, I. A.; Dremov, V. V.; Samarin, S. I.; Pokrovsky, A. S.; Harkov, D. V.

2013-01-01

The monograph is devoted to the application of graphite and graphite composites in science and technology. The structure and electrical properties, the technological aspects of production of high-strength synthetic graphites, the dynamics of the graphite destruction, traditionally used in the nuclear industry are discussed. It is focuses on the characteristics of graphitization and properties of graphite composites based on carbon isotope 13C. The book is based, generally, on the original res...

Mechanism of melting in submonolayer films of nitrogen molecules adsorbed on the basal planes of graphite

DEFF Research Database (Denmark)

Hansen, Flemming Yssing; Bruch, Ludwig Walter; Taub, H.

1995-01-01

The melting mechanism in submonolayer films of N-2 molecules adsorbed on the basal planes of graphite is studied using molecular-dynamics simulations. The melting is strongly correlated with the formation of vacancies in the films. As the temperature increases, the edges of the submonolayer patch...

Uranium Oxide Aerosol Transport in Porous Graphite

Energy Technology Data Exchange (ETDEWEB)

Blanchard, Jeremy; Gerlach, David C.; Scheele, Randall D.; Stewart, Mark L.; Reid, Bruce D.; Gauglitz, Phillip A.; Bagaasen, Larry M.; Brown, Charles C.; Iovin, Cristian; Delegard, Calvin H.; Zelenyuk, Alla; Buck, Edgar C.; Riley, Brian J.; Burns, Carolyn A.

2012-01-23

The objective of this paper is to investigate the transport of uranium oxide particles that may be present in carbon dioxide (CO2) gas coolant, into the graphite blocks of gas-cooled, graphite moderated reactors. The transport of uranium oxide in the coolant system, and subsequent deposition of this material in the graphite, of such reactors is of interest because it has the potential to influence the application of the Graphite Isotope Ratio Method (GIRM). The GIRM is a technology that has been developed to validate the declared operation of graphite moderated reactors. GIRM exploits isotopic ratio changes that occur in the impurity elements present in the graphite to infer cumulative exposure and hence the reactor’s lifetime cumulative plutonium production. Reference Gesh, et. al., for a more complete discussion on the GIRM technology.

Morphological changes of porphine films on graphite by perchloric and phosphoric electrolytes. An electrochemical-AFM study

Science.gov (United States)

Yivlialin, Rossella; Penconi, Marta; Bussetti, Gianlorenzo; Biroli, Alessio Orbelli; Finazzi, Marco; Duò, Lamberto; Bossi, Alberto

2018-06-01

Organic molecules have been proposed as promising candidates for electrode protection in acidic electrolytes. The use of tetraphenyl-porphines (H2TPP) as graphite surface-protecting agents in sulphuric acid (H2SO4) is one of the newest. With the aim of unveiling the mechanism of such a protective effect, in this paper we test the stability of a H2TPP thin film immersed in perchloric and phosphoric acid solutions that differently interact with porphyrins. The protective role of H2TPP is tested in the electrochemical potential range where the pristine graphite undergoes an oxidation process that erodes the surface and eventually exfoliate the stratified crystal. The electrochemical analysis is performed in a three-electrode cell, while the surface morphology is monitored ex-situ and in-situ by atomic force microscopy. Electrospray mass analysis is also employed to investigate the presence of H2TPP fragments in the solution. We find that the organic film is not stable in perchloric solution, while it is stable and avoids graphite surface corrosion in phosphoric acid solution. These results provide a rationale for the role played by free-base porphines in graphite protection.

Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition

Science.gov (United States)

D'Arcy, Julio M.; Tran, Henry D.; Stieg, Adam Z.; Gimzewski, James K.; Kaner, Richard B.

2012-05-01

A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated. Electronic supplementary information (ESI) available: Droplet coalescence, catenoid formation, mechanism of film growth, scanning electron micrographs showing carbon nanotube alignment, flexible transparent films of SWCNTs, AFM images of a chemically converted graphene film, and SEM images of SWCNT free-standing thin films. See DOI: 10.1039/c2nr00010e

A free-air system for long-term stable carbon isotope labeling of adult forest trees

Science.gov (United States)

Stable carbon (C) isotopes, in particular employed in labeling experiments, are an ideal tool to broaden our understanding of C dynamics in trees and forest ecosystems. Here, we present a free-air exposure system, named isoFACE, designed for long-term stable C isotope labeling in...

Stable-isotope-labeled carbohydrates and nucleosides: Synthesis and applications in chemistry and biology

Energy Technology Data Exchange (ETDEWEB)

Serianni, A.S. [Univ. of Notre Dame, IN (United States)

1994-12-01

Carbohydrates play important roles in many key biochemical processes in living cells. For example, they are metabolized to produce energy, mediate cell-cell recognition, and play an indirect role (as constituents of DNA and RNA) in DNA replication, RNA transcription, and protein synthesis. These roles, and others of comparable biochemical significance, have been studied to varying extends with the use of stable isotopically labeled molecules, usually in conjunction with NMR spectroscopy and/or mass spectrometry. For example, carbohydrate metabolism has been monitored in vitro and in vivo with the use of isotopically labeled compounds. Molecular aspects of cell-cell recognition, mediated by cell-surface glycoproteins and glycolipids, have been probed through NMR studies of isotopically labeled oligosaccharides. More recently, the solution behavior of DNA and RNA has been examined through the use of labeled oligonucleotides. In all of these pursuits, the effort and expense to prepare labeled molecules, both of which can be substantial, are more than offset by the wealth of information derived from these studies. This information often cannot be accessed, or can be accessed only with great difficulty, using natural (unlabeled) compounds.

Stable-isotope-labeled carbohydrates and nucleosides: Synthesis and applications in chemistry and biology

International Nuclear Information System (INIS)

Serianni, A.S.

1994-01-01

Carbohydrates play important roles in many key biochemical processes in living cells. For example, they are metabolized to produce energy, mediate cell-cell recognition, and play an indirect role (as constituents of DNA and RNA) in DNA replication, RNA transcription, and protein synthesis. These roles, and others of comparable biochemical significance, have been studied to varying extends with the use of stable isotopically labeled molecules, usually in conjunction with NMR spectroscopy and/or mass spectrometry. For example, carbohydrate metabolism has been monitored in vitro and in vivo with the use of isotopically labeled compounds. Molecular aspects of cell-cell recognition, mediated by cell-surface glycoproteins and glycolipids, have been probed through NMR studies of isotopically labeled oligosaccharides. More recently, the solution behavior of DNA and RNA has been examined through the use of labeled oligonucleotides. In all of these pursuits, the effort and expense to prepare labeled molecules, both of which can be substantial, are more than offset by the wealth of information derived from these studies. This information often cannot be accessed, or can be accessed only with great difficulty, using natural (unlabeled) compounds

Improved adaptability of polyaryl-ether-ether-ketone with texture pattern and graphite-like carbon film for bio-tribological applications

Science.gov (United States)

Ren, Siming; Huang, Jinxia; Cui, Mingjun; Pu, Jibin; Wang, Liping

2017-04-01

With the development of surface treatment technology, an increasing number of bearings, seals, dynamic friction drive or even biomedical devices involve a textured surface to improve lubrication and anti-wear. The present investigation has been conducted in order to evaluate the friction and wear behaviours of textured polyaryl-ether-ether-ketone (PEEK) coated with a graphite-like carbon (GLC) film sliding against stainless steel pin in biological medium. Compared with pure PEEK, the PEEK coated with GLC film shows excellent tribological performance with a low friction of 0.08 and long lifetime (wear volumes are about 3.78 × 10-4 mm3 for un-textured one and 2.60 × 10-4 mm3 for textured GLC film after 36,000 s of sliding) under physiological saline solution. In particular, the GLC film with appropriate dimple area density is effective to improve friction reduction and wear resistance properties of PEEK substrate under biological solution, which is attributed to the entrapment of wear debris in the dimples to inhibit the graphitization and the fluid dynamic pressure effect derived from the texture surface to increase the thickness in elastohydrodynamic lubrication (EHL) film during sliding motions. Moreover, the friction coefficient of GLC film under physiological saline solution decreases with the increase in the applied load. With the increasing applied load, the texture surface is responsible for accounting the improved wear resistance and a much lower graphitization of the GLC film during whole test.

A new method for the labelling of proteins with radioactive arsenic isotopes

Energy Technology Data Exchange (ETDEWEB)

Jennewein, M. [Institute of Nuclear Chemistry, Johannes Gutenberg University of Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany); Hermanne, A. [VUB Cyclotron, University of Brussels, Laarbeeklaan 103, 1090 Brussels (Belgium); Mason, R.P. [Department of Radiology, Advanced Radiological Sciences, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas (United States); Thorpe, P.E. [Department of Pharmacology and Simmons and Hamon Cancer Centers, University of Texas Southwestern Medical Center at Dallas, Dallas, TX (United States); Roesch, F. [Institute of Nuclear Chemistry, Johannes Gutenberg University of Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz (Germany)]. E-mail: frank.roesch@uni-mainz.de

2006-12-20

Radioarsenic labelled radiopharmaceuticals could be a valuable asset to positron emission tomography. In particular, the long half-lives of {sup 72}As (T{sub 1/2}=26h) and {sup 74}As (T{sub 1/2}=17.8d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of monoclonal antibodies (mab) in tumour tissue. In this work, a new method for the labelling of proteins with various radioactive arsenic isotopes was developed. For this purpose, two proteins, namely a chimeric IgG{sub 3} monoclonal antibody, ch3G4, directed against anionic phospholipids, and Rituxan (Rituximab), were labelled as a proof of principle with no-carrier-added radioarsenic isotopes ({sup 74}As and {sup 77}As). The developed labelling chemistry gives high yields (>99.9%), is reliable and could easily be transferred to automated labelling systems in a clinical environment. At least for the mab used in this work, this route of radioarsenic labelling does not affect the immunoreactivity of the product. The arsenic label stays stable for up to 72h at the molecular mass of the monoclonal antibody, which is in particular relevant to follow the pharmacology and pharmacokinetics of the labelled mab for several days.

Electrochemical reactivity at graphitic micro-domains on polycrystalline boron doped diamond thin-films electrodes

International Nuclear Information System (INIS)

Mahe, E.; Devilliers, D.; Comninellis, Ch.

2005-01-01

This paper deals with the electrochemical reactivity of boron doped diamond (BDD) electrodes. A comparative study has been carried out to show the influence of the presence of graphitic micro-domains upon the surface of these films. Those graphitic domains are sometimes present on as-grown boron doped diamond electrodes. The effect of doping a pure Csp 3 diamond electrode is established by highly oriented pyrolytic graphite (HOPG) abrasion onto the diamond surface. In order to establish the effect of doping on a pure Csp 3 diamond electrode, the amount of graphitic domains was increased by means of HOPG crystals grafted onto the BDD surface. Indeed that method allows the enrichment of the Csp 2 contribution of the electrode. The presence of graphitic domains can be correlatively associated with the presence of kinetically active redox sites. The electrochemical reactivity of boron doped diamond electrodes shows a distribution of kinetic constants on the whole surface of the electrode corresponding to different active sites. In this paper, we have studied by cyclic voltammetry and electrochemical impedance spectroscopy the kinetics parameters of the ferri/ferrocyanide redox couple in KCl electrolyte. A method is proposed to diagnose the presence of graphitic domains on diamond electrodes, and an electrochemical 'pulse cleaning' procedure is proposed to remove them

Affordable uniform isotope labeling with 2H, 13C and 15N in insect cells

International Nuclear Information System (INIS)

Sitarska, Agnieszka; Skora, Lukasz; Klopp, Julia; Roest, Susan; Fernández, César; Shrestha, Binesh; Gossert, Alvar D.

2015-01-01

For a wide range of proteins of high interest, the major obstacle for NMR studies is the lack of an affordable eukaryotic expression system for isotope labeling. Here, a simple and affordable protocol is presented to produce uniform labeled proteins in the most prevalent eukaryotic expression system for structural biology, namely Spodoptera frugiperda insect cells. Incorporation levels of 80 % can be achieved for 15 N and 13 C with yields comparable to expression in full media. For 2 H, 15 N and 2 H, 13 C, 15 N labeling, incorporation is only slightly lower with 75 and 73 %, respectively, and yields are typically twofold reduced. The media were optimized for isotope incorporation, reproducibility, simplicity and cost. High isotope incorporation levels for all labeling patterns are achieved by using labeled algal amino acid extracts and exploiting well-known biochemical pathways. The final formulation consists of just five commercially available components, at costs 12-fold lower than labeling media from vendors. The approach was applied to several cytosolic and secreted target proteins

Kinetic isotope effects in reaction of ferment oxidation of tritium-labelled D-galactosamine

International Nuclear Information System (INIS)

Akulov, G.P.; Korsakova, N.A.

1992-01-01

Primary, secondary and intramolecular kinetic isotopic effects in reaction of ferment oxidation of D-galactosamine labelled by tritium in position 6, were measured. When comparing values of the effects with previously obtained results for similar reaction D-[6- 3 H]galactose, it was ascertained that the presence of aminogroup in galactopyranosyl mainly affects kinetics of substrate-ferment complex formation stage. The possibility to use kinetic isotope effects for increase in molar activity of D-galactosamine, labelled by tritium in position 6, is shown

Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

Science.gov (United States)

Harvey, L J; Dainty, J R; Beattie, J H; Majsak-Newman, G; Wharf, S G; Reid, M D; Fairweather-Tait, S J

2005-03-01

To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. A longitudinal cross-over study. The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

Electrodeposition of Manganese-Nickel Oxide Films on a Graphite Sheet for Electrochemical Capacitor Applications

Directory of Open Access Journals (Sweden)

Hae-Min Lee

2014-01-01

Full Text Available Manganese-nickel (Mn-Ni oxide films were electrodeposited on a graphite sheet in a bath consisting of manganese acetate and nickel chloride, and the structural, morphological, and electrochemical properties of these films were investigated. The electrodeposited Mn-Ni oxide films had porous structures covered with nanofibers. The X-ray diffractometer pattern revealed the presence of separate manganese oxide (g-MnO2 and nickel oxide (NiO in the films. The electrodeposited Mn-Ni oxide electrode exhibited a specific capacitance of 424 F/g in Na2SO4 electrolyte. This electrode maintained 86% of its initial specific capacitance over 2000 cycles of the charge-discharge operation, showing good cycling stability.

Definitive Insight into the Graphite Oxide Reduction Mechanism by Deuterium Labeling

Czech Academy of Sciences Publication Activity Database

Jankovský, O.; Šimek, P.; Luxa, J.; Sedmidubský, D.; Tomandl, Ivo; Macková, Anna; Mikšová, Romana; Malinský, Petr; Pumera, M.; Sofer, Z.

2015-01-01

Roč. 80, č. 9 (2015), s. 1399-1407 ISSN 2192-6506 R&D Projects: GA ČR(CZ) GA15-09001S; GA ČR(CZ) GBP108/12/G108; GA MŠk LM2011019 Institutional support: RVO:61389005 Keywords : deuterium * graphene * isotopic labeling * reaction mechanisms * reduction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.836, year: 2015

Electrochemical reactivity at graphitic micro-domains on polycrystalline boron doped diamond thin-films electrodes

Energy Technology Data Exchange (ETDEWEB)

Mahe, E. [LI2C CNRS/UMR 7612, Laboratoire d' Electrochimie, Universite Pierre-et-Marie Curie - case courrier 51, 4, Place Jussieu, 75252 Paris Cedex 05 (France); Devilliers, D. [LI2C CNRS/UMR 7612, Laboratoire d' Electrochimie, Universite Pierre-et-Marie Curie - case courrier 51, 4, Place Jussieu, 75252 Paris Cedex 05 (France); Comninellis, Ch. [Unite de Genie Electrochimique, Institut de sciences des procedes chimiques et biologiques, Ecole Polytechnique Federale de Lausanne, 1015, Lausanne (Switzerland)

2005-04-01

This paper deals with the electrochemical reactivity of boron doped diamond (BDD) electrodes. A comparative study has been carried out to show the influence of the presence of graphitic micro-domains upon the surface of these films. Those graphitic domains are sometimes present on as-grown boron doped diamond electrodes. The effect of doping a pure Csp{sup 3} diamond electrode is established by highly oriented pyrolytic graphite (HOPG) abrasion onto the diamond surface. In order to establish the effect of doping on a pure Csp{sup 3} diamond electrode, the amount of graphitic domains was increased by means of HOPG crystals grafted onto the BDD surface. Indeed that method allows the enrichment of the Csp{sup 2} contribution of the electrode. The presence of graphitic domains can be correlatively associated with the presence of kinetically active redox sites. The electrochemical reactivity of boron doped diamond electrodes shows a distribution of kinetic constants on the whole surface of the electrode corresponding to different active sites. In this paper, we have studied by cyclic voltammetry and electrochemical impedance spectroscopy the kinetics parameters of the ferri/ferrocyanide redox couple in KCl electrolyte. A method is proposed to diagnose the presence of graphitic domains on diamond electrodes, and an electrochemical 'pulse cleaning' procedure is proposed to remove them.

Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films.

Science.gov (United States)

Wang, Hui; Wei, Can; Zhu, Kaiyi; Zhang, Yu; Gong, Chunhong; Guo, Jianhui; Zhang, Jiwei; Yu, Laigui; Zhang, Jingwei

2017-10-04

A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, I D /I G = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NH 4 NO 3 and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance).

Development of versatile isotopic labeling reagents for profiling the amine submetabolome by liquid chromatography–mass spectrometry

International Nuclear Information System (INIS)

Zhou, Ruokun; Huan, Tao; Li, Liang

2015-01-01

Highlights: • Two new reagents were developed for chemical isotope labeling mass spectrometry (MS). • They could be used to label amine-containing metabolites in a metabolomic sample. • The labeled metabolites could be detected with much improved sensitivity in MS. • One of the reagents could also help generate useful MS/MS spectra for structural analysis. • These reagents should be useful for quantitative metabolomics. - Abstract: Metabolomic profiling involves relative quantification of metabolites in comparative samples and identification of the significant metabolites that differentiate different groups (e.g., diseased vs. controls). Chemical isotope labeling (CIL) liquid chromatography–mass spectrometry (LC–MS) is an enabling technique that can provide improved metabolome coverage and metabolite quantification. However, chemical identification of labeled metabolites can still be a challenge. In this work, a new set of isotopic labeling reagents offering versatile properties to enhance both detection and identification are described. They were prepared by a glycine molecule (or its isotopic counterpart) and an aromatic acid with varying structures through a simple three-step synthesis route. In addition to relatively low costs of synthesizing the reagents, this reaction route allows adjusting reagent property in accordance with the desired application objective. To date, two isotopic reagents, 4-dimethylaminobenzoylamido acetic acid N-hydroxylsuccinimide ester (DBAA-NHS) and 4-methoxybenzoylamido acetic acid N-hydroxylsuccinimide ester (MBAA-NHS), for labeling the amine-containing metabolites (i.e., amine submetabolome) have been synthesized. The labeling conditions and the related LC–MS method have been optimized. We demonstrate that DBAA labeling can increase the metabolite detectability because of the presence of an electrospray ionization (ESI)-active dimethylaminobenzoyl group. On the other hand, MBAA labeled metabolites can be fragmented

Development of versatile isotopic labeling reagents for profiling the amine submetabolome by liquid chromatography–mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ruokun; Huan, Tao; Li, Liang, E-mail: Liang.Li@ualberta.ca

2015-06-30

Highlights: • Two new reagents were developed for chemical isotope labeling mass spectrometry (MS). • They could be used to label amine-containing metabolites in a metabolomic sample. • The labeled metabolites could be detected with much improved sensitivity in MS. • One of the reagents could also help generate useful MS/MS spectra for structural analysis. • These reagents should be useful for quantitative metabolomics. - Abstract: Metabolomic profiling involves relative quantification of metabolites in comparative samples and identification of the significant metabolites that differentiate different groups (e.g., diseased vs. controls). Chemical isotope labeling (CIL) liquid chromatography–mass spectrometry (LC–MS) is an enabling technique that can provide improved metabolome coverage and metabolite quantification. However, chemical identification of labeled metabolites can still be a challenge. In this work, a new set of isotopic labeling reagents offering versatile properties to enhance both detection and identification are described. They were prepared by a glycine molecule (or its isotopic counterpart) and an aromatic acid with varying structures through a simple three-step synthesis route. In addition to relatively low costs of synthesizing the reagents, this reaction route allows adjusting reagent property in accordance with the desired application objective. To date, two isotopic reagents, 4-dimethylaminobenzoylamido acetic acid N-hydroxylsuccinimide ester (DBAA-NHS) and 4-methoxybenzoylamido acetic acid N-hydroxylsuccinimide ester (MBAA-NHS), for labeling the amine-containing metabolites (i.e., amine submetabolome) have been synthesized. The labeling conditions and the related LC–MS method have been optimized. We demonstrate that DBAA labeling can increase the metabolite detectability because of the presence of an electrospray ionization (ESI)-active dimethylaminobenzoyl group. On the other hand, MBAA labeled metabolites can be fragmented

Structural features of the adsorption layer of pentacene on the graphite surface and the PMMA/graphite hybrid surface

Science.gov (United States)

Fadeeva, A. I.; Gorbunov, V. A.; Litunenko, T. A.

2017-08-01

Using the molecular dynamics and the Monte Carlo methods, we have studied the structural features and growth mechanism of the pentacene film on graphite and polymethylmethacrylate /graphite surfaces. Monolayer capacity and molecular area, optimal angles between the pentacene molecules and graphite and PMMA/graphite surfaces as well as the characteristic angles between the neighboring pentacene molecules in the adsorption layer were estimated. It is shown that the orientation of the pentacene molecules in the film is determined by a number of factors, including the surface concentration of the molecules, relief of the surface, presence or absence of the polymer layer and its thickness. The pentacene molecules adsorbed on the graphite surface keep a horizontal position relative to the long axis at any surface coverage/thickness of the film. In the presence of the PMMA layer on the graphite, the increase of the number of pentacene molecules as well as the thickness of the PMMA layer induce the change of molecular orientation from predominantly horizontal to vertical one. The reason for such behavior is supposed to be the roughness of the PMMA surface.

Charge transport in films of Geobacter sulfurreducens on graphite electrodes as a function of film thickness

KAUST Repository

Jana, Partha Sarathi; Katuri, Krishna; Kavanagh, Paul; Kumar, Amit Ravi Pradeep; Leech, Dó nal

2014-01-01

Harnessing, and understanding the mechanisms of growth and activity of, biofilms of electroactive bacteria (EAB) on solid electrodes is of increasing interest, for application to microbial fuel and electrolysis cells. Microbial electrochemical cell technology can be used to generate electricity, or higher value chemicals, from organic waste. The capability of biofilms of electroactive bacteria to transfer electrons to solid anodes is a key feature of this emerging technology, yet the electron transfer mechanism is not fully characterized as yet. Acetate oxidation current generated from biofilms of an EAB, Geobacter sulfurreducens, on graphite electrodes as a function of time does not correlate with film thickness. Values of film thickness, and the number and local concentration of electrically connected redox sites within Geobacter sulfurreducens biofilms as well as a charge transport diffusion co-efficient for the biofilm can be estimated from non-turnover voltammetry. The thicker biofilms, of 50 ± 9 μm, display higher charge transport diffusion co-efficient than that in thinner films, as increased film porosity of these films improves ion transport, required to maintain electro-neutrality upon electrolysis. This journal is © the Partner Organisations 2014.

Carbon-14 in neutron-irradiated graphite for graphite-moderated reactors. Joint research

Energy Technology Data Exchange (ETDEWEB)

Fujii, Kimio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Matsuo, Hideto [Radioactive Waste Management and Nuclear Facility Decommissioning Technology Center, Tokyo (Japan)

2002-12-01

The graphite moderated gas cooled reactor operated by the Japan Atomic Power Company was stopped its commercial operation on March 1998, and the decommissioning process has been started. Graphite material is often used as the moderator and the reflector materials in the core of the gas cooled reactor. During the operation, a long life nuclide of {sup 14}C is generated in the graphite by several transmutation reactions. Separation of {sup 14}C isotope and the development of the separation method have been recognized to be critical issues for the decommissioning of the reactor core. To understand the current methodologies for the carbon isotope separation, literature on the subject was surveyed. Also, those on the physical and chemical behavior of {sup 14}C were surveyed. This is because the larger part of the nuclides in the graphite is produced from {sup 14}N by (n,p) reaction, and the location of them in the material tends to be different from those of the other carbon atoms. This report summarizes the result of survey on the open literature about the behavior of {sup 14}C and the separation methods, including the list of the literature on these subjects. (author)

Expeditious syntheses of stable and radioactive isotope-labeled anticonvulsant agent, JNJ-26990990, and its metabolites.

Science.gov (United States)

Lin, Ronghui; Weaner, Larry E; Hoerr, David C; Salter, Rhys; Gong, Yong

2013-01-01

Syntheses of stable and radioactive isotope-labeled anticonvulsant agent, JNJ-26990990, that is, N-(benzo[b]thien-3-ylmethyl)-sulfamide and its metabolites are described. [(13)C(15)N]Benzo[b]thiophene-3-carbonitrile was first prepared by coupling of 3-bromo-benzo[b]thiophene with [(13)C(15)N]-copper cyanide. The resultant [(13)C(15)N]benzo[b]thiophene-3-carbonitrile was reduced with lithium aluminum deuteride to give [(13)CD2(15)N]benzo[b]thiophen-3-yl-methylamine; which was then coupled with sulfamide to afford [(13)CD2(15)N]-N-(benzo[b]thien-3-ylmethyl)-sulfamide, the stable isotope-labeled compound with four stable isotope atoms. Direct oxidation of [(13)CD2(15)N]-N-(benzo[b]thien-3-ylmethyl)-sulfamide with hydrogen peroxide and peracetic acid gave the stable isotope-labeled sulfoxide and sulfone metabolites. On the other hand, radioactive (14)C-labeled N-(benzo[b]thien-3-ylmethyl)-sulfamide was prepared conveniently by sequential coupling of 3-bromo-benzo[b]thiophene with [(14)C]-copper cyanide, reduction of the carbonitrile to carboxaldehyde, and reductive amination with sulfamide. Copyright © 2013 John Wiley & Sons, Ltd.

Fabrication and electrical resistivity of Mo-doped VO2 thin films coated on graphite conductive plates by a sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Choi, W.; Jung, H.M.; Um, S. [Hanyang Univ., Seoul (Korea, Republic of). School of Mechanical Engineering

2008-07-01

Vanadium oxides (VO2) can be used in optical devices, thermochromic smart windows and sensors. This paper reported on a study in which vanadium pentoxide (V2O5) powder was prepared and mixed with Molybdenum Oxides (MoO3) to form Mo-doped and -undoped VO2 thin films by a sol-gel method on graphite conductive substrates. The micro-structure and chemical compositions of the Mo-doped and -undoped VO2 thin films was investigated using X-Ray diffraction and scanning electron microscopy. Changes in electrical resistivity were measured as a function of the stoichiometric compositions between vanadium and molybdenum. In this study. Mo-doped and -undoped VO2 thin films showed the typical metal to insulator transition (MIT), where temperature range could be adjusted by modifying the dopant atomic ratio. The through-plane substrate structure of the Mo-doped layer influences the electrical resistivity of the graphite substrate. As the amount of the molybdenum increases, the electrical resistivity of the graphite conductive substrate decreases in the lower temperature range below the freezing point of water. The experimental results showed that if carefully controlled, thermal dissipation of VO2 thin films can be used as a self-heating source to melt frozen water with the electrical current flowing through the graphite substrate. 3 refs., 3 figs.

Heating Isotopically Labeled Bernal Stacked Graphene: A Raman Spectroscopy Study

Czech Academy of Sciences Publication Activity Database

Ek Weis, Johan; da Costa, Sara; Frank, Otakar; Kalbáč, Martin

2014-01-01

Roč. 5, č. 3 (2014), s. 549-554 ISSN 1948-7185 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : Bernal * graphene * isotopic labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.458, year: 2014

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

Directory of Open Access Journals (Sweden)

Neil Spencer

2011-06-01

Full Text Available Isotopic labelling studies were performed to probe a proposed 1,2-aryl shift in the gold-catalysed cycloisomerisation of alkynyl aziridines into 2,4-disubstituted pyrroles. Two isotopomers of the expected skeletal rearrangement product were identified using 13C-labelling and led to a revised mechanism featuring two distinct skeletal rearrangements. The mechanistic proposal has been rationalised against the reaction of a range of 13C- and deuterium-labelled substrates.

Synthesis of 13C and 2H labelled retinals: spectroscopic investigations on isotopically labelled rhodopsin and bacteriorhodopsin

International Nuclear Information System (INIS)

Pardoen, J.A.

1986-01-01

In order to develop probes of the structure of chromophores, the author introduces isotopic modifications at specific chromophoric positions as structural probes. To obtain bacteriorhodopsin, rhodopsin and their photoproducts labelled in the chromophore at selected positions, bacterioopsin and opsin were reacted with the appropriate labelled a11-trans and 11-cis retinals. The author describes the synthesis of a11-trans retinal selectively 13 C labelled at different positions. The characterization of these labelled a11-trans retinals by mass spectrometry, 300 MHz 1 H NMR and 75 MHz 13 C NMR spectroscopy is given. The photochemical preparation and isolation of the pure 9-, 11- and 13-cis forms is described in the experimental part. (Auth.)

Sensing site-specific structural characteristics and chirality using vibrational circular dichroism of isotope labeled peptides.

Science.gov (United States)

Keiderling, Timothy A

2017-12-01

Isotope labeling has a long history in chemistry as a tool for probing structure, offering enhanced sensitivity, or enabling site selection with a wide range of spectroscopic tools. Chirality sensitive methods such as electronic circular dichroism are global structural tools and have intrinsically low resolution. Consequently, they are generally insensitive to modifications to enhance site selectivity. The use of isotope labeling to modify vibrational spectra with unique resolvable frequency shifts can provide useful site-specific sensitivity, and these methods have been recently more widely expanded in biopolymer studies. While the spectral shifts resulting from changes in isotopic mass can provide resolution of modes from specific parts of the molecule and can allow detection of local change in structure with perturbation, these shifts alone do not directly indicate structure or chirality. With vibrational circular dichroism (VCD), the shifted bands and their resultant sign patterns can be used to indicate local conformations in labeled biopolymers, particularly if multiple labels are used and if their coupling is theoretically modeled. This mini-review discusses selected examples of the use of labeling specific amides in peptides to develop local structural insight with VCD spectra. © 2017 Wiley Periodicals, Inc.

Controlling wear failure of graphite-like carbon film in aqueous environment: Two feasible approaches

International Nuclear Information System (INIS)

Wang Yongxin; Wang Liping; Xue Qunji

2011-01-01

Friction and wear behaviors of graphite-like carbon (GLC) films in aqueous environment were investigated by a reciprocating sliding tribo-meter with ball-on-disc contact. Film structures and wear scars were studied by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and a non-contact 3D surface profiler. A comprehensive wear model of the GLC film in aqueous environment was established, and two feasible approaches to control critical factor to the corresponding wear failure were discussed. Results showed that wear loss of GLC films in aqueous environment was characterized by micro-plough and local delamination. Due to the significant material loss, local delamination of films was critical to wear failure of GLC film in aqueous environment if the film was not prepared properly. The initiation and propagation of micro-cracks within whole films closely related to the occurrence of the films delamination from the interface between interlayer and substrate. The increase of film density by adjusting the deposition condition would significantly reduce the film delamination from substrate, meanwhile, fabricating a proper interlayer between substrate and GLC films to prevent the penetration of water molecules into the interface between interlayer and substrate could effectively eliminate the delamination.

Removal of 14C from Irradiated Graphite for Graphite Recycle and Waste Volume Reduction

International Nuclear Information System (INIS)

Dunzik-Gougar, Mary Lou; Windes, Will; Marsden, Barry

2014-01-01

The aim of the research presented here was to identify the chemical form of 14 C in irradiated graphite. A greater understanding of the chemical form of this longest-lived isotope in irradiated graphite will inform not only management of legacy waste, but also development of next generation gas-cooled reactors. Approximately 250,000 metric tons of irradiated graphite waste exists worldwide, with the largest single quantity originating in the Magnox and AGR reactors of UK. The waste quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation I gas-cooled, graphite moderated reactors. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 14 C, with a half-life of 5730 years.

Stable isotope labeling of glycoprotein expressed in silkworms using immunoglobulin G as a test molecule

Energy Technology Data Exchange (ETDEWEB)

Yagi, Hirokazu [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan); Nakamura, Masatoshi [National Institute of Agrobiological Sciences, Genetic Resources Conservation Research Unit, Genetic Resources Center (Japan); Yokoyama, Jun [Taiyo Nippon Sanso Corporation, Tsukuba Laboratories (Japan); Zhang, Ying; Yamaguchi, Takumi [National Institutes of Natural Sciences, Institute for Molecular Science and Okazaki Institute for Integrative Bioscience (Japan); Kondo, Sachiko [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan); Kobayashi, Jun [Yamaguchi University, Department of Biological and Environmental Sciences, Faculty of Agriculture (Japan); Kato, Tatsuya; Park, Enoch Y. [Shizuoka University, Laboratory of Biotechnology, Research Institute of Green Science and Technology (Japan); Nakazawa, Shiori [Nagoya University, Sugashima Marine Biological Laboratory, Graduate School of Science (Japan); Hashii, Noritaka; Kawasaki, Nana [National Institute of Health Sciences, Division of Biological Chemistry and Biologicals (Japan); Kato, Koichi, E-mail: kkato@phar.nagoya-cu.ac.jp [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan)

2015-06-15

Silkworms serve as promising bioreactors for the production of recombinant proteins, including glycoproteins and membrane proteins, for structural and functional protein analyses. However, lack of methodology for stable isotope labeling has been a major deterrent to using this expression system for nuclear magnetic resonance (NMR) structural biology. Here we developed a metabolic isotope labeling technique using commercially available silkworm larvae. The fifth instar larvae were infected with baculoviruses for co-expression of recombinant human immunoglobulin G (IgG) as a test molecule, with calnexin as a chaperone. They were subsequently reared on an artificial diet containing {sup 15}N-labeled yeast crude protein extract. We harvested 0.1 mg of IgG from larva with a {sup 15}N-enrichment ratio of approximately 80 %. This allowed us to compare NMR spectral data of the Fc fragment cleaved from the silkworm-produced IgG with those of an authentic Fc glycoprotein derived from mammalian cells. Therefore, we successfully demonstrated that our method enables production of isotopically labeled glycoproteins for NMR studies.

Carbon-14 Graphitization Chemistry

Science.gov (United States)

Miller, James; Collon, Philippe; Laverne, Jay

2014-09-01

Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare 14C isotopes can be separated from the stable 14N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.

Existing and emerging technologies for measuring stable isotope labelled retinol in biological samples: isotope dilution analysis of body retinol stores.

Science.gov (United States)

Preston, Tom

2014-01-01

This paper discusses some of the recent improvements in instrumentation used for stable isotope tracer measurements in the context of measuring retinol stores, in vivo. Tracer costs, together with concerns that larger tracer doses may perturb the parameter under study, demand that ever more sensitive mass spectrometric techniques are developed. GCMS is the most widely used technique. It has high sensitivity in terms of sample amount and uses high resolution GC, yet its ability to detect low isotope ratios is limited by background noise. LCMSMS may become more accessible for tracer studies. Its ability to measure low level stable isotope tracers may prove superior to GCMS, but it is isotope ratio MS (IRMS) that has been designed specifically for low level stable isotope analysis through accurate analysis of tracer:tracee ratios (the tracee being the unlabelled species). Compound-specific isotope analysis, where GC is interfaced to IRMS, is gaining popularity. Here, individual 13C-labelled compounds are separated by GC, combusted to CO2 and transferred on-line for ratiometric analysis by IRMS at the ppm level. However, commercially-available 13C-labelled retinol tracers are 2 - 4 times more expensive than deuterated tracers. For 2H-labelled compounds, GC-pyrolysis-IRMS has now become more generally available as an operating mode on the same IRMS instrument. Here, individual compounds are separated by GC and pyrolysed to H2 at high temperature for analysis by IRMS. It is predicted that GC-pyrolysis-IRMS will facilitate low level tracer procedures to measure body retinol stores, as has been accomplished in the case of fatty acids and amino acids. Sample size requirements for GC-P-IRMS may exceed those of GCMS, but this paper discusses sample preparation procedures and predicts improvements, particularly in the efficiency of sample introduction.

Fabrication of SnO2-Reduced Graphite Oxide Monolayer-Ordered Porous Film Gas Sensor with Tunable Sensitivity through Ultra-Violet Light Irradiation

Science.gov (United States)

Xu, Shipu; Sun, Fengqiang; Yang, Shumin; Pan, Zizhao; Long, Jinfeng; Gu, Fenglong

2015-01-01

A new graphene-based composite structure, monolayer-ordered macroporous film composed of a layer of orderly arranged macropores, was reported. As an example, SnO2-reduced graphite oxide monolayer-ordered macroporous film was fabricated on a ceramic tube substrate under the irradiation of ultra-violet light (UV), by taking the latex microsphere two-dimensional colloid crystal as a template. Graphite oxide sheets dispersed in SnSO4 aqueous solution exhibited excellent affinity with template microspheres and were in situ incorporated into the pore walls during UV-induced growth of SnO2. The growing and the as-formed SnO2, just like other photocatalytic semiconductor, could be excited to produce electrons and holes under UV irradiation. Electrons reduced GO and holes adsorbed corresponding negative ions, which changed the properties of the composite film. This film was directly used as gas-sensor and was able to display high sensitivity in detecting ethanol gas. More interestingly, on the basis of SnO2-induced photochemical behaviours, this sensor demonstrated tunable sensitivity when UV irradiation time was controlled during the fabrication process and post in water, respectively. This study provides efficient ways of conducting the in situ fabrication of a semiconductor-reduced graphite oxide film device with uniform surface structure and controllable properties. PMID:25758292

Study of film graphene/graphene oxide obtained by partial reduction chemical of oxide graphite; Estudo de filme de grafeno/oxido de grafeno obtido por reducao quimica parcial do oxido de grafite

Energy Technology Data Exchange (ETDEWEB)

Gascho, J.L.S.; Costa, S.F.; Hoepfner, J.C.; Pezzin, S.H., E-mail: juliagascho@hotmail.com [Universidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

2014-07-01

This study investigated the morphology of graphene/graphene oxide film obtained by partial chemical reduction of graphite oxide (OG) as well as its resistance to solvents. Films of graphene/graphene oxide are great candidates for replacement of indium oxide doped with tin (ITO) in photoelectric devices. The OG was obtained from natural graphite, by Hummer's method modified, and its reduction is made by using sodium borohydride. Infrared spectroscopy analysis of Fourier transform (FTIR), Xray diffraction (XRD) and scanning electron microscopy, high-resolution (SEM/FEG) for the characterization of graphene/graphene oxide film obtained were performed. This film proved to be resilient, not dispersing in any of the various tested solvents (such as ethanol, acetone and THF), even under tip sonication, this resistance being an important property for the applications. Furthermore, the film had a morphology similar to that obtained by other preparation methods.(author)

Isotopically modified compounds

International Nuclear Information System (INIS)

Kuruc, J.

2009-01-01

In this chapter the nomenclature of isotopically modified compounds in Slovak language is described. This chapter consists of following parts: (1) Isotopically substituted compounds; (2) Specifically isotopically labelled compounds; (3) Selectively isotopically labelled compounds; (4) Non-selectively isotopically labelled compounds; (5) Isotopically deficient compounds.

Correlated XANES, TEM, and NanoSIMS of presolar graphite grains

Science.gov (United States)

Groopman, Evan E.; Nittler, Larry R.

2018-01-01

We report correlated XANES, TEM, and NanoSIMS measurements of twelve presolar graphite grains extracted from primitive meteorites and for which isotopic data indicate predominantly Type-II supernovae origins. We find continued evidence for isotopic heterogeneities in presolar graphite grains, including the first observation of a radial gradient in the inferred initial 26Al/27Al within a presolar graphite grain. The XANES spectra of these samples show a variety of minor absorbances near the C K-edge, attributable to vinyl-keto, aliphatic, carboxyl, and carbonate molecules, as well as possible damage during sample preparation. Each sample exhibits homogeneous C K-edge XANES spectra within the graphite, however, showing no correlation with isotopic heterogeneities. Gradients in the isotope ratios of C, N, O, and Al could be due to both processes during condensation, e.g., mixing in stellar ejecta and granular transport, and post-condensation effects, such as isotope dilution and exchange with isotopically normal material in the early Solar System or laboratory, the latter of which is a significant issue for high-density presolar graphite grains. It remains unknown whether the mechanisms behind isotope exchange would also affect the local chemistry and therefore the XANES spectra. Ti L-edge XANES from most Ti-rich subgrains match standard spectra for TiC and potentially TiCN. A rare rutile (TiO2) subgrain has been identified, though it lacks the lowest energy L3 peak typically seen in standard spectra. Ca has also been identified by EDXS in TiC subgrains, likely due to the decay of live 44Ti at the time of formation. Future NanoSIMS measurements will determine the variability of initial 44Ti in TiC subgrains, an important constraint on mixing in the ejecta of the grains' parent supernovae.

Performance of isobaric and isotopic labeling in quantitative plant proteomics

DEFF Research Database (Denmark)

Nogueira, Fábio C S; Palmisano, Giuseppe; Schwämmle, Veit

2012-01-01

, and quantitation. In the present work, we have used LC-MS to compare an isotopic (ICPL) and isobaric (iTRAQ) chemical labeling technique to quantify proteins in the endosperm of Ricinus communis seeds at three developmental stages (IV, VI, and X). Endosperm proteins of each stage were trypsin-digested in...

Identifying and quantifying proteolytic events and the natural N terminome by terminal amine isotopic labeling of substrates.

Science.gov (United States)

Kleifeld, Oded; Doucet, Alain; Prudova, Anna; auf dem Keller, Ulrich; Gioia, Magda; Kizhakkedathu, Jayachandran N; Overall, Christopher M

2011-09-22

Analysis of the sequence and nature of protein N termini has many applications. Defining the termini of proteins for proteome annotation in the Human Proteome Project is of increasing importance. Terminomics analysis of protease cleavage sites in degradomics for substrate discovery is a key new application. Here we describe the step-by-step procedures for performing terminal amine isotopic labeling of substrates (TAILS), a 2- to 3-d (depending on method of labeling) high-throughput method to identify and distinguish protease-generated neo-N termini from mature protein N termini with all natural modifications with high confidence. TAILS uses negative selection to enrich for all N-terminal peptides and uses primary amine labeling-based quantification as the discriminating factor. Labeling is versatile and suited to many applications, including biochemical and cell culture analyses in vitro; in vivo analyses using tissue samples from animal and human sources can also be readily performed. At the protein level, N-terminal and lysine amines are blocked by dimethylation (formaldehyde/sodium cyanoborohydride) and isotopically labeled by incorporating heavy and light dimethylation reagents or stable isotope labeling with amino acids in cell culture labels. Alternatively, easy multiplex sample analysis can be achieved using amine blocking and labeling with isobaric tags for relative and absolute quantification, also known as iTRAQ. After tryptic digestion, N-terminal peptide separation is achieved using a high-molecular-weight dendritic polyglycerol aldehyde polymer that binds internal tryptic and C-terminal peptides that now have N-terminal alpha amines. The unbound naturally blocked (acetylation, cyclization, methylation and so on) or labeled mature N-terminal and neo-N-terminal peptides are recovered by ultrafiltration and analyzed by tandem mass spectrometry (MS/MS). Hierarchical substrate winnowing discriminates substrates from the background proteolysis products and

Synthetic routes to some isotopically labelled intermediates for diterpenoid biosynthesis

International Nuclear Information System (INIS)

Dawson, R.M.; Godfrey, I.M.; Hogg, R.W.; Knox, J.R.

1989-01-01

The exo-15-hydrogen of ent-kaurene can be exchanged through a reversible ene reaction in a convenient and efficient procedure which has the potential for giving high specific activity 3 H-labelling. Copalol, the (Z)-double bond stereoisomer, and the allylic alcohol isomers ent-manool and ent-epimanool have been obtained through divergent synthetic pathways involving a 15,16-bisnor ketone intermediate. These pathways have also allowed the four compounds to be obtained with 14 C-labelling. A method, involving a Wittig reaction to form a vinyl bromide intermediate, has been developed for obtaining copalol, as the trityl ether derivative, with stereospecific isotopic labelling of one or the other of the hydrogens of the exocyclic methylene group. 27 refs., figs

Affordable uniform isotope labeling with {sup 2}H, {sup 13}C and {sup 15}N in insect cells

Energy Technology Data Exchange (ETDEWEB)

Sitarska, Agnieszka; Skora, Lukasz; Klopp, Julia; Roest, Susan; Fernández, César; Shrestha, Binesh; Gossert, Alvar D., E-mail: alvar.gossert@novartis.com [Novartis Institutes for BioMedical Research (Switzerland)

2015-06-15

For a wide range of proteins of high interest, the major obstacle for NMR studies is the lack of an affordable eukaryotic expression system for isotope labeling. Here, a simple and affordable protocol is presented to produce uniform labeled proteins in the most prevalent eukaryotic expression system for structural biology, namely Spodoptera frugiperda insect cells. Incorporation levels of 80 % can be achieved for {sup 15}N and {sup 13}C with yields comparable to expression in full media. For {sup 2}H,{sup 15}N and {sup 2}H,{sup 13}C,{sup 15}N labeling, incorporation is only slightly lower with 75 and 73 %, respectively, and yields are typically twofold reduced. The media were optimized for isotope incorporation, reproducibility, simplicity and cost. High isotope incorporation levels for all labeling patterns are achieved by using labeled algal amino acid extracts and exploiting well-known biochemical pathways. The final formulation consists of just five commercially available components, at costs 12-fold lower than labeling media from vendors. The approach was applied to several cytosolic and secreted target proteins.

Pulsed Laser Deposition of Tungsten Thin Films on Graphite

International Nuclear Information System (INIS)

Kassem, W.; Tabbal, M.; Roumie, M.

2011-01-01

Thin coatings of Tungsten were deposited on substrates fabricated by pre-depositing graphite thin layers on Si(100) wafers. We ablate pure W target using a 20 ns KrF excimer laser (248 nm) in an Ar ambient. The effect of background gas pressure, substrate temperature, and laser fluence, on the properties of the deposited W layers is studied using several techniques including X-Ray Diffraction, Atomic Force Microscopy, surface profilometry, and Rutherford Back-Scattering spectrometry. Our results indicate that the deposited layers consist of the well-crystallized body-centered-cubic α-W phase with bulk-like properties, particularly for films deposited at a substrate temperature of 450 0 C, laser fluence greater than 400mJ, and pressure of about 10mTorr. (author)

Syntheses with isotopically labelled carbon. Methyl iodide, formaldehyde and cyanide

International Nuclear Information System (INIS)

Finn, R.D.; Boothe, T.E.; Vora, M.M.; Hildner, J.C.; Emran, A.M.; Kothari, P.J.

1984-01-01

Many of the uniquely labelled synthetic precursors currently employed in the design of sophisticated radiolabelled compounds have their origins in the field of hot atom chemistry. Particularly, the development during the past few years of automated, on-line synthetic procedures which combine the nuclear reaction, hot atom and classical chemistry, and rapid purification methods has allowed the incorporation of useful radionuclides into suitable compounds of chemical and biochemical interest. The application of isotopically labelled methyl iodide, formaldehyde, and cyanide anion as synthetic intermediates in research involving human physiology and nuclear medicine, as well as their contributions to other scientific methodology, is reviewed. (author)

Highly efficient residue-selective labeling with isotope-labeled Ile, Leu, and Val using a new auxotrophic E. coli strain

International Nuclear Information System (INIS)

Miyanoiri, Yohei; Ishida, Yojiro; Takeda, Mitsuhiro; Terauchi, Tsutomu; Inouye, Masayori; Kainosho, Masatsune

2016-01-01

We recently developed a practical protocol for preparing proteins bearing stereo-selectively 13 C-methyl labeled leucines and valines, instead of the commonly used 13 C-methyl labeled precursors for these amino acids, by E. coli cellular expression. Using this protocol, proteins with any combinations of isotope-labeled or unlabeled Leu and Val residues were prepared, including some that could not be prepared by the precursor methods. However, there is still room for improvement in the labeling efficiencies for Val residues, using the methods with labeled precursors or Val itself. This is due to the fact that the biosynthesis of Val could not be sufficiently suppressed, even by the addition of large amounts of Val or its precursors. In this study, we completely solved this problem by using a mutant strain derived from E. coli BL21(DE3), in which the metabolic pathways depending on two enzymes, dihydroxy acid dehydratase and β-isopropylmalate dehydrogenase, are completely aborted by deleting the ilvD and leuB genes, which respectively encode these enzymes. The ΔilvD E. coli mutant terminates the conversion from α,β-dihydroxyisovalerate to α-ketoisovalerate, and the conversion from α,β-dihydroxy-α-methylvalerate to α-keto-β-methylvalerate, which produce the preceding precursors for Val and Ile, respectively. By the further deletion of the leuB gene, the conversion from Val to Leu was also fully terminated. Taking advantage of the double-deletion mutant, ΔilvDΔleuB E. coli BL21(DE3), an efficient and residue-selective labeling method with various isotope-labeled Ile, Leu, and Val residues was established.

Highly efficient residue-selective labeling with isotope-labeled Ile, Leu, and Val using a new auxotrophic E. coli strain

Energy Technology Data Exchange (ETDEWEB)

Miyanoiri, Yohei [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Ishida, Yojiro [Rutgers University-Robert Wood Johnson Medical School, Center for Advanced Biotechnology and Medicine (United States); Takeda, Mitsuhiro [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Terauchi, Tsutomu [Tokyo Metropolitan University, Graduate School of Science and Engineering (Japan); Inouye, Masayori [Rutgers University-Robert Wood Johnson Medical School, Center for Advanced Biotechnology and Medicine (United States); Kainosho, Masatsune, E-mail: kainosho@tmu.ac.jp [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan)

2016-06-15

We recently developed a practical protocol for preparing proteins bearing stereo-selectively {sup 13}C-methyl labeled leucines and valines, instead of the commonly used {sup 13}C-methyl labeled precursors for these amino acids, by E. coli cellular expression. Using this protocol, proteins with any combinations of isotope-labeled or unlabeled Leu and Val residues were prepared, including some that could not be prepared by the precursor methods. However, there is still room for improvement in the labeling efficiencies for Val residues, using the methods with labeled precursors or Val itself. This is due to the fact that the biosynthesis of Val could not be sufficiently suppressed, even by the addition of large amounts of Val or its precursors. In this study, we completely solved this problem by using a mutant strain derived from E. coli BL21(DE3), in which the metabolic pathways depending on two enzymes, dihydroxy acid dehydratase and β-isopropylmalate dehydrogenase, are completely aborted by deleting the ilvD and leuB genes, which respectively encode these enzymes. The ΔilvD E. coli mutant terminates the conversion from α,β-dihydroxyisovalerate to α-ketoisovalerate, and the conversion from α,β-dihydroxy-α-methylvalerate to α-keto-β-methylvalerate, which produce the preceding precursors for Val and Ile, respectively. By the further deletion of the leuB gene, the conversion from Val to Leu was also fully terminated. Taking advantage of the double-deletion mutant, ΔilvDΔleuB E. coli BL21(DE3), an efficient and residue-selective labeling method with various isotope-labeled Ile, Leu, and Val residues was established.

Mass spectrometric studies of stable isotope-labelled carboxylic acid derivatives

International Nuclear Information System (INIS)

Andersson, B.Aa.; Dinger, F.; Dinh-Nguyen, N.

1975-01-01

Low resolution mass spectra of deuterium and carbon-13 labelled fatty acid pyrrolidides are discussed. The simple fragmentation pattern of pyrrolidides makes them superior to other derivatives, regarding location of isotopes. Deuteriation of ethylenic fatty acid pyrrolidides therefore seems to be an improved method to locate carbon-carbon double bonds by mass spectrometry. (author)

Raman spectroscopy of isotopically labeled two-layer graphene

Czech Academy of Sciences Publication Activity Database

Kalbáč, Martin; Kong, J.; Kavan, Ladislav; Dresselhaus, M. S.

2012-01-01

Roč. 249, č. 12 (2012), s. 2500-2502 ISSN 0370-1972 R&D Projects: GA AV ČR IAA400400911; GA AV ČR IAA400400804; GA AV ČR KAN200100801; GA MŠk ME09060; GA ČR GAP204/10/1677; GA ČR GBP208/12/G016; GA ČR(CZ) GAP208/12/1062 Institutional support: RVO:61388955 Keywords : electrochemical doping * isotope labeling * graphene Subject RIV: CG - Electrochemistry Impact factor: 1.489, year: 2012

The graphite deposit at Borrowdale (UK): A catastrophic mineralizing event associated with Ordovician magmatism

Science.gov (United States)

Ortega, L.; Millward, D.; Luque, F. J.; Barrenechea, J. F.; Beyssac, O.; Huizenga, J.-M.; Rodas, M.; Clarke, S. M.

2010-04-01

The volcanic-hosted graphite deposit at Borrowdale in Cumbria, UK, was formed through precipitation from C-O-H fluids. The δ 13C data indicate that carbon was incorporated into the mineralizing fluids by assimilation of carbonaceous metapelites of the Skiddaw Group by andesite magmas of the Borrowdale Volcanic Group. The graphite mineralization occurred as the fluids migrated upwards through normal conjugate fractures forming the main subvertical pipe-like bodies. The mineralizing fluids evolved from CO 2-CH 4-H 2O mixtures (XCO 2 = 0.6-0.8) to CH 4-H 2O mixtures. Coevally with graphite deposition, the andesite and dioritic wall rocks adjacent to the veins were intensely hydrothermally altered to a propylitic assemblage. The initial graphite precipitation was probably triggered by the earliest hydration reactions in the volcanic host rocks. During the main mineralization stage, graphite precipitated along the pipe-like bodies due to CO 2 → C + O 2. This agrees with the isotopic data which indicate that the first graphite morphologies crystallizing from the fluid (cryptocrystalline aggregates) are isotopically lighter than those crystallizing later (flakes). Late chlorite-graphite veins were formed from CH 4-enriched fluids following the reaction CH 4 + O 2 → C + 2H 2O, producing the successive precipitation of isotopically lighter graphite morphologies. Thus, as mineralization proceeded, water-generating reactions were involved in graphite precipitation, further favouring the propylitic alteration. The structural features of the pipe-like mineralized bodies as well as the isotopic homogeneity of graphite suggest that the mineralization occurred in a very short period of time.

Efficient segmental isotope labeling of multi-domain proteins using Sortase A

Energy Technology Data Exchange (ETDEWEB)

Freiburger, Lee, E-mail: lee.freiburger@tum.de; Sonntag, Miriam, E-mail: miriam.sonntag@mytum.de; Hennig, Janosch, E-mail: janosch.hennig@helmholtz-muenchen.de [Helmholtz Zentrum München, Institute of Structural Biology (Germany); Li, Jian, E-mail: lijianzhongbei@163.com [Chinese Academy of Sciences, Tianjin Institute of Industrial Biotechnology (China); Zou, Peijian, E-mail: peijian.zou@helmholtz-muenchen.de; Sattler, Michael, E-mail: sattler@helmholtz-muenchen.de [Helmholtz Zentrum München, Institute of Structural Biology (Germany)

2015-09-15

NMR studies of multi-domain protein complexes provide unique insight into their molecular interactions and dynamics in solution. For large proteins domain-selective isotope labeling is desired to reduce signal overlap, but available methods require extensive optimization and often give poor ligation yields. We present an optimized strategy for segmental labeling of multi-domain proteins using the S. aureus transpeptidase Sortase A. Critical improvements compared to existing protocols are (1) the efficient removal of cleaved peptide fragments by centrifugal filtration and (2) a strategic design of cleavable and non-cleavable affinity tags for purification. Our approach enables routine production of milligram amounts of purified segmentally labeled protein for NMR and other biophysical studies.

Automatic isotope gas analysis of tritium labelled organic materials Pt. 1

International Nuclear Information System (INIS)

Gacs, I.; Mlinko, S.

1978-01-01

A new automatic procedure developed to convert tritium in HTO hydrogen for subsequent on-line gas counting is described. The water containing tritium is introduced into a column prepared from molecular sieve-5A and heated to 550 deg C. The tritium is transferred by isotopic exchange into hydrogen flowing through the column. The radioactive gas is led into an internal detector for radioactivity measurement. The procedure is free of memory effects, provides quantitative recovery with analytical reproducibility better than 0.5% rel. at a preset number of counts. The experimental and analytical results indicate that isotopic exchange between HTO and hydrogen over a column prepared from alumina or molecular sieve-5A can be successfully applied for the quantitative transfer of tritium from HTO into hydrogen for on-line gas countinq. This provides an analytical procedure for the automatic determination of tritium in water with an analytical reproducibility better than 0.5% rel. The exchange process will also be suitable for rapid tritium transfer from water formed during the decomposition of tritium-labelled organic compounds or biological materials. The application of the procedure in automatic isotope gas analysis of organic materials labelled with tritium will be described in subsequent papers (Parts II and III). (T.G.)

Wetting phenomena in films of molecular hydrogen isotopes

International Nuclear Information System (INIS)

Albrecht, U.; Conradt, R.; Herminghaus, S.; Leiderer, P.

1996-01-01

We have investigated various aspects of the wetting behavior of hydrogen films (including the heavier isotopes) using surface plasmon resonance, light scattering, and photoelectron emission. Studies in the vicinity of the triple point (T 3 (H 2 )=13,96 K) confirmed the known >, and gave no indications for a prewetting transition in this range. At low temperatures (T 3 /3) the equilibrium film thickness reaches only a few monolayers. Thicker films, prepared by quench-condensation of H 2 gas at 1.5 K, undergo a dewetting process during annealing: most of the film material contracts to clusters, and in between the films thins down to its equilibrium thickness. This surface diffusion process is thermally activated, with an activation energy of 23 K (in the case of H 2 ). The dewetting kinetics has not revealed any indication for a surface-molten layer on the solid films at low temperatures, or for a superfluid component

Tests of intestinal absorption using carbon-14-labeled isotopes

International Nuclear Information System (INIS)

Fromm, H.; Sarva, R.P.

1983-01-01

Beta radiation-emitting isotopes are being used increasingly in diagnostic gastroenterology for the study of absorption. The major reason for the popularity of radioisotopes is that their use is convenient for patient and physician alike. They often obviate naso- or orointestinal intubation and the collection, storage, and analysis of stool. The radioactivity used for the studies of digestive and absorptive processes is small and is not hazardous. In spite of the safety of the radiolabeled compounds, their use is restricted in children and pregnant women. Therefore, for most tests, promising alternative methods that make use of the stable isotope of carbon, /sup 13/C, instead of the radioactive /sup 14/C have been developed. The analysis of stable isotopes requires more sophisticated technology than that of radioactive compounds, however. Only a few centers presently are equipped and staffed to analyze stable isotopes on a routine basis. In contrast, the analysis of radioactive isotopes has become a routine procedure in almost ever major laboratory. The last decade has brought the development of several radioactive absorption tests. The clinically most useful tests relate to the study of bile acid, fat, lactose, and xylose absorption. All of these tests utilize the excretion rate of /sup 14/CO/sub 2/ in breath after ingestion of a /sup 14/C-labeled compound as a measure of the rate of its absorption or malabsorption

THE FIRST DISCOVERY OF PRESOLAR GRAPHITE GRAINS FROM THE HIGHLY REDUCING QINGZHEN (EH3) METEORITE

Energy Technology Data Exchange (ETDEWEB)

Xu, Yuchen; Lin, Yangting; Zhang, Jianchao; Hao, Jialong, E-mail: linyt@mail.iggcas.ac.cn [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

2016-07-10

Presolar graphite grains have been extensively studied, but are limited in carbonaceous chondrites, particularly in Murchison (CM2) and Orgueil (CI1), which sampled materials from the oxidizing regions in the solar nebula. Here, we report the first discovery of presolar graphite grains from the Qingzhen (EH3) enstatite chondrite which formed under a highly reducing condition. Eighteen presolar graphite grains were identified by C-isotope mapping of the low-density fraction (1.75–1.85 g cm{sup 3}) from Qingzhen acid residue. Another 58 graphite spherules were found in different areas of the same sample mount using a scanning electron microscope and were classified into three morphologies, including cauliflower, onion, and cauliflower–onion. The Raman spectra of these spherules vary from ordered, disordered, and glassy to kerogen-like, suggestive of a wide range of thermal metamorphisms. NanoSIMS analysis of the C- and Si-isotopes of these graphite spherules confirmed 23 presolar grains. The other 35 graphite spherules have no significant isotopic anomalies, but they share similar morphologies and Raman spectra with the presolar ones. Another three grains were identified during NanoSIMS analysis. Of all the 44 presolar graphite grains identified, six grains show {sup 28}Si-excesses, suggestive of supernovae origins, and four grains are {sup 12}C- and {sup 29,30}Si-rich, consistent with low-metallicity asymptotic giant branch star origins. Another two graphite spherules have extremely low {sup 12}C/{sup 13}C ratios with marginal solar Si-isotopes. The morphologies, Raman spectra, and C- and Si-isotopic distributions of the presolar graphite grains from the Qingzhen enstatite chondrite are similar to those of the low-density fractions from Murchison carbonaceous chondrites. This study suggests a homogeneous distribution of presolar graphite grains in the solar nebula.

THE FIRST DISCOVERY OF PRESOLAR GRAPHITE GRAINS FROM THE HIGHLY REDUCING QINGZHEN (EH3) METEORITE

International Nuclear Information System (INIS)

Xu, Yuchen; Lin, Yangting; Zhang, Jianchao; Hao, Jialong

2016-01-01

Presolar graphite grains have been extensively studied, but are limited in carbonaceous chondrites, particularly in Murchison (CM2) and Orgueil (CI1), which sampled materials from the oxidizing regions in the solar nebula. Here, we report the first discovery of presolar graphite grains from the Qingzhen (EH3) enstatite chondrite which formed under a highly reducing condition. Eighteen presolar graphite grains were identified by C-isotope mapping of the low-density fraction (1.75–1.85 g cm 3 ) from Qingzhen acid residue. Another 58 graphite spherules were found in different areas of the same sample mount using a scanning electron microscope and were classified into three morphologies, including cauliflower, onion, and cauliflower–onion. The Raman spectra of these spherules vary from ordered, disordered, and glassy to kerogen-like, suggestive of a wide range of thermal metamorphisms. NanoSIMS analysis of the C- and Si-isotopes of these graphite spherules confirmed 23 presolar grains. The other 35 graphite spherules have no significant isotopic anomalies, but they share similar morphologies and Raman spectra with the presolar ones. Another three grains were identified during NanoSIMS analysis. Of all the 44 presolar graphite grains identified, six grains show 28 Si-excesses, suggestive of supernovae origins, and four grains are 12 C- and 29,30 Si-rich, consistent with low-metallicity asymptotic giant branch star origins. Another two graphite spherules have extremely low 12 C/ 13 C ratios with marginal solar Si-isotopes. The morphologies, Raman spectra, and C- and Si-isotopic distributions of the presolar graphite grains from the Qingzhen enstatite chondrite are similar to those of the low-density fractions from Murchison carbonaceous chondrites. This study suggests a homogeneous distribution of presolar graphite grains in the solar nebula.

Deposition of polycrystalline Cd{sub 1-x}Zn{sub x} Te films on ZnTe/graphite and graphite substrates by close-spaced sublimation

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Tamotsu; Akiba, Sho; Takahashi, Kohei; Nagatsuka, Satsuki; Kanda, Yohei [Department of Electrical and Electronic Engineering, Kisarazu National College of Technology, 2-11-1 Kiyomidai-higashi, Kisarazu, Chiba 292-0041 (Japan); Tokuda, Satoshi; Kishihara, Hiroyuki; Sato, Toshiyuki [Technology Research Laboratory, Shimadzu Corporation, 3-9-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)

2014-07-15

The effects of a ZnTe layer on the deposition of a Cd{sub 1-x}Zn{sub x}Te (CZT) layer in the initial stage of the close-spaced sublimation (CSS) deposition were investigated. The deposition rate was almost constant in the initial stage of the CdTe deposition on the ZnTe/graphite substrates. However, the deposition rate within 1 minute was lower than that after 1 minute in the CdTe deposition on graphite substrates. This result suggests that nucleation of CdTe directly deposited on graphite substrate is difficult when compared to that with a ZnTe layer. Furthermore, the effects of CdCl{sub 2} and ZnTe additions to the CdTe sources in the CSS deposition were also investigated. Both the grain size and the intensity of donor-acceptor pair (DAP) emission in photoluminescence (PL) spectra were decreased by the effect of CdCl{sub 2} addition. Zn content in CZT films was controlled by the ZnTe ratio in the CdTe/ZnTe powder sources. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Sulfur Isotope Exchange between S-35 Labeled Inorganic Sulfur-Compounds in Anoxic Marine-Sediments

DEFF Research Database (Denmark)

FOSSING, H.; THODEANDERSEN, S.; JØRGENSEN, BB

1992-01-01

Isotope exchange reactions between S-35-labeled sulfur compounds were studied in anoxic estuarine sediment slurries at 21-degrees-C and pH 7.4-7.7. Two experiments labeled with radioactive elemental sulfur (S-35-degrees) and one labeled with radioactive sulfate ((SO42-)-S-35) were performed as time......% of the total S-35 was recovered in the SIGMA-HS- pool in less than 1.5 h. With no detectable SIGMA-HS- (less than 1-mu-M) in the slurry, 58% of the total S-35 was observed in the pyrite pool within 1.5 h. The FeS pool received up to 31% of all S-35 added. The rapid S-35 incorporation from S-35-degrees...... into SIGMA-HS- and FeS pools was explained by isotope exchange reactions. In contrast, there was evidence that the radioactivity observed in the 'pyrite pool' was caused by adhesion of the added S-35-degrees to the FeS2 grains. In all S-35-degrees-labeled experiments we also observed oxidation...

Hydroponic isotope labeling of entire plants and high-performance mass spectrometry for quantitative plant proteomics.

Science.gov (United States)

Bindschedler, Laurence V; Mills, Davinia J S; Cramer, Rainer

2012-01-01

Hydroponic isotope labeling of entire plants (HILEP) combines hydroponic plant cultivation and metabolic labeling with stable isotopes using (15)N-containing inorganic salts to label whole and mature plants. Employing (15)N salts as the sole nitrogen source for HILEP leads to the production of healthy-looking plants which contain (15)N proteins labeled to nearly 100%. Therefore, HILEP is suitable for quantitative plant proteomic analysis, where plants are grown in either (14)N- or (15)N-hydroponic media and pooled when the biological samples are collected for relative proteome quantitation. The pooled (14)N-/(15)N-protein extracts can be fractionated in any suitable way and digested with a protease for shotgun proteomics, using typically reverse phase liquid chromatography nanoelectrospray ionization tandem mass spectrometry (RPLC-nESI-MS/MS). Best results were obtained with a hybrid ion trap/FT-MS mass spectrometer, combining high mass accuracy and sensitivity for the MS data acquisition with speed and high-throughput MS/MS data acquisition, increasing the number of proteins identified and quantified and improving protein quantitation. Peak processing and picking from raw MS data files, protein identification, and quantitation were performed in a highly automated way using integrated MS data analysis software with minimum manual intervention, thus easing the analytical workflow. In this methodology paper, we describe how to grow Arabidopsis plants hydroponically for isotope labeling using (15)N salts and how to quantitate the resulting proteomes using a convenient workflow that does not require extensive bioinformatics skills.

Advances in the graphitization protocol at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF) in Brazil

Energy Technology Data Exchange (ETDEWEB)

Macario, Kita D., E-mail: kitamacario@gmail.com [Departamento de Física, Instituto deFísica, Universidade Federal Fluminense, Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza s/n°, Niterói, RJ, 24210-346 (Brazil); Oliveira, Fabiana M. [Departamento de Física, Instituto deFísica, Universidade Federal Fluminense, Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza s/n°, Niterói, RJ, 24210-346 (Brazil); Carvalho, Carla [Departamento de Geoquímica, Instituto de Química, Universidade Federal Fluminense, Campus do Valonguinho, Outeiro São João Batista, s/n°, Niterói, RJ, 24020-150 (Brazil); Santos, Guaciara M.; Xu, Xiaomei [Department of Earth System Science, B321 Croul Hall, University of California Irvine, Irvine, CA, 92697-3100 (United States); Chanca, Ingrid S.; Alves, Eduardo Q.; Jou, Renata M.; Oliveira, Maria Isabela; Pereira, Bruna B.; Moreira, Vinicius; Muniz, Marcelo C.; Linares, Roberto; Gomes, Paulo Roberto Silveira; Meigikos dos Anjos, Roberto [Departamento de Física, Instituto deFísica, Universidade Federal Fluminense, Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza s/n°, Niterói, RJ, 24210-346 (Brazil); and others

2015-10-15

In this paper, we summarize the sample preparation methods currently used at the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF) in Brazil. We also report on a series of results with regards to the graphitization protocol. Tests with different temperatures and baking times were performed, and carbon stable isotope ratios of graphite were measured by an EA–IRMS (elemental analyzer coupled with an isotopic ratio mass spectrometer) to infer the completeness of the graphitization reaction. We monitored the muffle furnace temperature using an independent thermocouple and found a −60 °C offset, which may have caused the lower graphitization yields (detected from the large isotopic fractionation on several reference materials targets). At a temperature of 520 °C, the isotopic fractionation in the graphitization reaction was systematically lower (−5‰ in average) and the overall scattering was reduced. As long as isotopic fractionation corrections are made using the online stable isotopes ratios provided by the AMS system, the accuracy of the {sup 14}C results should be maintained.

Noninvasive imaging of protein metabolic labeling in single human cells using stable isotopes and Raman microscopy

NARCIS (Netherlands)

van Manen, H.J.; Lenferink, Aufrid T.M.; Otto, Cornelis

2008-01-01

We have combined nonresonant Raman microspectroscopy and spectral imaging with stable isotope labeling by amino acids in cell culture (SILAC) to selectively detect the incorporation of deuterium-labeled phenylalanine, tyrosine, and methionine into proteins in intact, single HeLa cells. The C−D

Isotope labeling for NMR studies of macromolecular structure and interactions

International Nuclear Information System (INIS)

Wright, P.E.

1994-01-01

Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform 13 C, 15 N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific 13 C and 15 N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions

Isotope labeling for NMR studies of macromolecular structure and interactions

Energy Technology Data Exchange (ETDEWEB)

Wright, P.E. [Scripps Research Institute, La Jolla, CA (United States)

1994-12-01

Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform {sup 13}C, {sup 15}N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific {sup 13}C and {sup 15}N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions.

Stable isotope labeled n-alkanes to assess digesta passage kinetics through the digestive tract of ruminants

NARCIS (Netherlands)

Warner, D.; Ferreira, L.M.M.; Breuer, M.J.H.; Dijkstra, J.; Pellikaan, W.F.

2013-01-01

We describe the use of carbon stable isotope (13C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically 13C labeled ryegrass plants were pulse dosed intraruminally in four

Auto-inducing media for uniform isotope labeling of proteins with 15N, 13C and 2H

International Nuclear Information System (INIS)

Guthertz, Nicolas; Klopp, Julia; Winterhalter, Aurélie; Fernández, César; Gossert, Alvar D.

2015-01-01

Auto-inducing media for protein expression offer many advantages like robust reproducibility, high yields of soluble protein and much reduced workload. Here, an auto-inducing medium for uniform isotope labelling of proteins with 15 N, 13 C and/or 2 H in E. coli is presented. So far, auto-inducing media have not found widespread application in the NMR field, because of the prohibitively high cost of labeled lactose, which is an essential ingredient of such media. Here, we propose using lactose that is only selectively labeled on the glucose moiety. It can be synthesized from inexpensive and readily available substrates: labeled glucose and unlabeled activated galactose. With this approach, uniformly isotope labeled proteins were expressed in unattended auto-inducing cultures with incorporation of 13 C, 15 N of 96.6 % and 2 H, 15 N of 98.8 %. With the present protocol, the NMR community could profit from the many advantages that auto-inducing media offer

Growth of Hexagonal Columnar Nanograin Structured SiC Thin Films on Silicon Substrates with Graphene–Graphitic Carbon Nanoflakes Templates from Solid Carbon Sources

Directory of Open Access Journals (Sweden)

Wanshun Zhao

2013-04-01

Full Text Available We report a new method for growing hexagonal columnar nanograin structured silicon carbide (SiC thin films on silicon substrates by using graphene–graphitic carbon nanoflakes (GGNs templates from solid carbon sources. The growth was carried out in a conventional low pressure chemical vapor deposition system (LPCVD. The GGNs are small plates with lateral sizes of around 100 nm and overlap each other, and are made up of nanosized multilayer graphene and graphitic carbon matrix (GCM. Long and straight SiC nanograins with hexagonal shapes, and with lateral sizes of around 200–400 nm are synthesized on the GGNs, which form compact SiC thin films.

X-ray diffraction characterization of epitaxial CVD diamond films with natural and isotopically modified compositions

Energy Technology Data Exchange (ETDEWEB)

Prokhorov, I. A., E-mail: igor.prokhorov@mail.ru [Russian Academy of Sciences, Space Materials Science Laboratory, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics”, Kaluga Branch (Russian Federation); Voloshin, A. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Ralchenko, V. G.; Bolshakov, A. P. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Romanov, D. A. [Bauman Moscow State Technical University, Kaluga Branch (Russian Federation); Khomich, A. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Sozontov, E. A. [National Research Centre “Kurchatov Institute” (Russian Federation)

2016-11-15

Comparative investigations of homoepitaxial diamond films with natural and modified isotopic compositions, grown by chemical vapor deposition (CVD) on type-Ib diamond substrates, are carried out using double-crystal X-ray diffractometry and topography. The lattice mismatch between the substrate and film is precisely measured. A decrease in the lattice constant on the order of (Δa/a){sub relax} ∼ (1.1–1.2) × 10{sup –4} is recorded in isotopically modified {sup 13}C (99.96%) films. The critical thicknesses of pseudomorphic diamond films is calculated. A significant increase in the dislocation density due to the elastic stress relaxation is revealed by X-ray topography.

Addressing Raman features of individual layers in isotopically labeled Bernal stacked bilayer graphene

Czech Academy of Sciences Publication Activity Database

da Costa, Sara; Ek Weis, Johan; Frank, Otakar; Fridrichová, Michaela; Kalbáč, Martin

2016-01-01

Roč. 3, č. 2 (2016), 025022 ISSN 2053-1583 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : graphene bilayer * Raman spectroscopy * isotope labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.937, year: 2016

Phase behavior of mixed submonolayer films of krypton and xenon on graphite.

Science.gov (United States)

Patrykiejew, A; Sokołowski, S

2012-04-14

Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two- and three-dimensional models of the systems studied. It has been demonstrated that out-of-plane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit non-monotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Two-dimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (√3×√3)R30° phase upon the increase of temperature. Such a superstructure does not appear when a three-dimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the krypton-like (with incipient triple point) to the xenon-like (with ordinary triple point).

Testing isotopic labeling with [¹³C₆]glucose as a method of advanced glycation sites identification.

Science.gov (United States)

Kielmas, Martyna; Kijewska, Monika; Stefanowicz, Piotr; Szewczuk, Zbigniew

2012-12-01

The Maillard reaction occurring between reducing sugars and reactive amino groups of biomolecules leads to the formation of a heterogeneous mixture of compounds: early, intermediate, and advanced glycation end products (AGEs). These compounds could be markers of certain diseases and of the premature aging process. Detection of Amadori products can be performed by various methods, including MS/MS techniques and affinity chromatography on immobilized boronic acid. However, the diversity of the structures of AGEs makes detection of these compounds more difficult. The aim of this study was to test a new method of AGE identification based on isotope (13)C labeling. The model protein (hen egg lysozyme) was modified with an equimolar mixture of [(12)C(6)]glucose and [(13)C(6)]glucose and then subjected to reduction of the disulfide bridges followed by tryptic hydrolysis. The digest obtained was analyzed by LC-MS. The glycation products were identified on the basis of characteristic isotopic patterns resulting from the use of isotopically labeled glucose. This method allowed identification of 38 early Maillard reaction products and five different structures of the end glycation products. This isotopic labeling technique combined with LC-MS is a sensitive method for identification of advanced glycation end products even if their chemical structure is unknown. Copyright © 2012 Elsevier Inc. All rights reserved.

Laser surface graphitization to control friction of diamond-like carbon coatings

Science.gov (United States)

Komlenok, Maxim S.; Kononenko, Vitaly V.; Zavedeev, Evgeny V.; Frolov, Vadim D.; Arutyunyan, Natalia R.; Chouprik, Anastasia A.; Baturin, Andrey S.; Scheibe, Hans-Joachim; Shupegin, Mikhail L.; Pimenov, Sergei M.

2015-11-01

To study the role of laser surface graphitization in the friction behavior of laser-patterned diamond-like carbon (DLC) films, we apply the scanning probe microscopy (SPM) in the lateral force mode (LFM) which allows to obtain simultaneously the lateral force and topography images and to determine local friction levels in laser-irradiated and original surface areas. Based on this approach in the paper, we report on (1) laser surface microstructuring of hydrogenated a-C:H and hydrogen-free ta-C films in the regime of surface graphitization using UV laser pulses of 20-ns duration and (2) correlation between the structure and friction properties of the laser-patterned DLC surface on micro/nanoscale using SPM/LFM technique. The SPM/LFM data obtained for the surface relief gratings of graphitized microstructures have evidenced lower friction forces in the laser-graphitized regions. For the hydrogenated DLC films, the reversible frictional behavior of the laser-graphitized micropatterns is found to take place during LFM imaging at different temperatures (20 and 120 °C) in ambient air. It is revealed that the lateral force distribution in the laser-graphitized areas is shifted to higher friction levels (relative to that of the unirradiated surface) at temperature 120 °C and returned back to the lower friction during the sample cooling to 20 °C, thus confirming an influence of adsorbed water layers on the nanofriction properties of laser-graphitized micropatterns on the film surface.

Production of large quantities of isotopically labeled protein in Pichia pastoris by fermentation

International Nuclear Information System (INIS)

Wood, Matthew J.; Komives, Elizabeth A.

1999-01-01

Heterologous expression in Pichia pastoris has many of the advantages of eukaryotic expression, proper folding and disulfide bond formation, glycosylation, and secretion. Contrary to other eukaryotic systems, protein production from P.pastoris occurs in simple minimal defined media making this system attractive for production of labeled proteins for NMR analysis. P.pastoris is therefore the expression system of choice for NMR of proteins that cannot be refolded from inclusion bodies or that require post-translational modifications for proper folding or function. The yield of expressed proteins from P.pastoris depends critically on growth conditions, and attainment of high cell densities by fermentation has been shown to improve protein yields by 10-100-fold. Unfortunately, the cost of the isotopically enriched fermentation media components, particularly 15NH4OH, is prohibitively high. We report fermentation methods that allow for both 15N- labeling from (15NH4)2SO4 and 13C-labeling from 13C-glucose or 13C-glycerol of proteins produced in Pichia pastoris. Expression of an 83 amino acid fragment of thrombomodulin with two N-linked glycosylation sites shows that fermentation is more cost effective than shake flask growth for isotopic enrichment

Methane generated from graphite--tritium interaction

International Nuclear Information System (INIS)

Coffin, D.O.; Walthers, C.R.

1979-01-01

When hydrogen isotopes are separated by cryogenic distillation, as little as 1 ppM of methane will eventually plug the still as frost accumulates on the column packings. Elemental carbon exposed to tritium generates methane spontaneously, and yet some dry transfer pumps, otherwise compatible with tritium, convey the gas with graphite rotors. This study was to determine the methane production rate for graphite in tritium. A pump manufacturer supplied graphite samples that we exposed to tritium gas at 0.8 atm. After 137 days we measured a methane synthesis rate of 6 ng/h per cm 2 of graphite exposed. At this rate methane might grow to a concentration of 0.01 ppM when pure tritium is transferred once through a typical graphite--rotor transfer pump. Such a low methane level will not cause column blockage, even if the cryogenic still is operated continuously for many years

Friction and wear of carbon-graphite materials for high energy brakes

Science.gov (United States)

Bill, R. C.

1975-01-01

Caliper-type brakes simulation experiments were conducted on seven different carbon-graphite material formulations against a steel disk material and against a carbon-graphite disk material. The effects of binder level, boron carbide (B4C) additions, graphite fiber additions, and graphite cloth reinforcement on friction and wear behavior were investigated. Reductions in binder level and additions of B4C each resulted in increased wear. The wear rate was not affected by the addition of graphite fibers. Transition to severe wear and high friction was observed in the case of graphite-cloth-reinforced carbon sliding against a disk of similar composition. This transition was related to the disruption of a continuous graphite shear film that must form on the sliding surfaces if low wear is to occur. The exposure of the fiber structure of the cloth constituent is believed to play a role in the shear film disruption.

Stable isotope labeling – Liquid chromatography/mass spectrometry for quantitative analysis of androgenic and progestagenic steroids

International Nuclear Information System (INIS)

Guo, Ning; Liu, Ping; Ding, Jun; Zheng, Shu-Jian; Yuan, Bi-Feng; Feng, Yu-Qi

2016-01-01

Steroid hormones play important roles in mammal at very low concentrations and are associated with numerous endocrinology and oncology diseases. Therefore, quantitative analysis of steroid hormones can provide crucial information for uncovering underlying mechanisms of steroid hormones related diseases. In the current study, we developed a sensitive method for the detection of steroid hormones (progesterone, dehydroepiandrosterone, testosterone, pregnenolone, 17-hydroxyprogesterone, androstenedione and 17α-hydroxypregnenolone) in body fluids by stable isotope labeling coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. In this respect, a pair of isotopes labeling reagents, Girard reagent P (GP) and d_5-Girard reagent P (d_5-GP), were synthesized and utilized to label steroid hormones in follicular fluid samples and steroid hormone standards, respectively. The heavy labeled standards were used as internal standards for quantification to minimize quantitation deviation in MS analysis due to the matrix and ion suppression effects. The ionization efficiencies of steroid hormones were greatly improved by 4–504 folds through the introduction of a permanent charged moiety of quaternary ammonium from GP. Using the developed method, we successfully quantified steroid hormones in human follicular fluid. We found that the contents of testosterone and androstenedione exhibited significant increase while the content of pregnenolone had significant decrease in follicular fluid of polycystic ovarian syndrome (PCOS) patients compared with healthy controls, indicating that these steroid hormones with significant change may contribute to the pathogenesis of PCOS. Taken together, the developed stable isotope labeling coupled LC-ESI-MS/MS analysis demonstrated to be a promising method for the sensitive and accurate determination of steroid hormones, which may facilitate the in-depth investigation of steroid hormones related

Stable isotope labeling – Liquid chromatography/mass spectrometry for quantitative analysis of androgenic and progestagenic steroids

Energy Technology Data Exchange (ETDEWEB)

Guo, Ning; Liu, Ping; Ding, Jun; Zheng, Shu-Jian; Yuan, Bi-Feng; Feng, Yu-Qi, E-mail: yqfeng@whu.edu.cn

2016-01-28

Steroid hormones play important roles in mammal at very low concentrations and are associated with numerous endocrinology and oncology diseases. Therefore, quantitative analysis of steroid hormones can provide crucial information for uncovering underlying mechanisms of steroid hormones related diseases. In the current study, we developed a sensitive method for the detection of steroid hormones (progesterone, dehydroepiandrosterone, testosterone, pregnenolone, 17-hydroxyprogesterone, androstenedione and 17α-hydroxypregnenolone) in body fluids by stable isotope labeling coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. In this respect, a pair of isotopes labeling reagents, Girard reagent P (GP) and d{sub 5}-Girard reagent P (d{sub 5}-GP), were synthesized and utilized to label steroid hormones in follicular fluid samples and steroid hormone standards, respectively. The heavy labeled standards were used as internal standards for quantification to minimize quantitation deviation in MS analysis due to the matrix and ion suppression effects. The ionization efficiencies of steroid hormones were greatly improved by 4–504 folds through the introduction of a permanent charged moiety of quaternary ammonium from GP. Using the developed method, we successfully quantified steroid hormones in human follicular fluid. We found that the contents of testosterone and androstenedione exhibited significant increase while the content of pregnenolone had significant decrease in follicular fluid of polycystic ovarian syndrome (PCOS) patients compared with healthy controls, indicating that these steroid hormones with significant change may contribute to the pathogenesis of PCOS. Taken together, the developed stable isotope labeling coupled LC-ESI-MS/MS analysis demonstrated to be a promising method for the sensitive and accurate determination of steroid hormones, which may facilitate the in-depth investigation of steroid hormones

Investigation into reaction of heterogenous isotopic exchange with gaseoUs tritium in solution for preparation labelled lipid compounds

International Nuclear Information System (INIS)

Shevchenko, V.P.; Myasoedov, N.F.

1983-01-01

The applicability of the method of heterogeneous catalytic isotopic exchange with gaseous tritium in the solution for the production of labelled lipide preparations is studied. Labelled saturated and unsaturated aliphatic acids, prostaglandins, phospholipides and sphingolipides are prepared

Adaptation of a Commonly Used, Chemically Defined Medium for Human Embryonic Stem Cells to Stable Isotope Labeling with Amino Acids in Cell Culture

DEFF Research Database (Denmark)

Liberski, A. R.; Al-Noubi, M. N.; Rahman, Z. H.

2013-01-01

Metabolic labeling with stable isotopes is a prominent technique for comparative quantitative proteomics, and stable isotope labeling with amino acids in cell culture (SILAC) is the most commonly used approach. SILAC is, however, traditionally limited to simple tissue culture regimens and only ra...

In situ electrochemical atomic force microscope study on graphite electrodes

Energy Technology Data Exchange (ETDEWEB)

Hirasawa, K.A.; Sato, Tomohiro; Asahina, Hitoshi; Yamaguchi, Shoji; Mori, Shoichiro [Mitsubishi Chemical Corp., Inashiki, Ibaraki (Japan). Tsukuba Research Center

1997-04-01

Interest in the formation of the solid electrolyte interphase (SEI) film on graphite electrodes has increased recently in the quest to improve the performance of lithium-ion batteries. Topographic and frictional changes on the surface of a highly oriented pyrolytic graphite electrode in 1 M LiCiO{sub 4} ethylene carbonate/ethylmethyl carbonate (1:1) electrolyte were examined during charge and discharge by in situ electrochemical atomic force microscopy and friction force microscopy simultaneously in real-time. Solid electrolyte interphase film formation commenced at approximately 2 V vs. Li/Li{sup +} and stable film formation with an island-like morphology was observed below approximately 0.9 V vs. Li/Li{sup +}. Further experiments on a KS-44 graphite/polyvinylidene difluoride binder composite electrode showed similar phenomena.

IsoMS: automated processing of LC-MS data generated by a chemical isotope labeling metabolomics platform.

Science.gov (United States)

Zhou, Ruokun; Tseng, Chiao-Li; Huan, Tao; Li, Liang

2014-05-20

A chemical isotope labeling or isotope coded derivatization (ICD) metabolomics platform uses a chemical derivatization method to introduce a mass tag to all of the metabolites having a common functional group (e.g., amine), followed by LC-MS analysis of the labeled metabolites. To apply this platform to metabolomics studies involving quantitative analysis of different groups of samples, automated data processing is required. Herein, we report a data processing method based on the use of a mass spectral feature unique to the chemical labeling approach, i.e., any differential-isotope-labeled metabolites are detected as peak pairs with a fixed mass difference in a mass spectrum. A software tool, IsoMS, has been developed to process the raw data generated from one or multiple LC-MS runs by peak picking, peak pairing, peak-pair filtering, and peak-pair intensity ratio calculation. The same peak pairs detected from multiple samples are then aligned to produce a CSV file that contains the metabolite information and peak ratios relative to a control (e.g., a pooled sample). This file can be readily exported for further data and statistical analysis, which is illustrated in an example of comparing the metabolomes of human urine samples collected before and after drinking coffee. To demonstrate that this method is reliable for data processing, five (13)C2-/(12)C2-dansyl labeled metabolite standards were analyzed by LC-MS. IsoMS was able to detect these metabolites correctly. In addition, in the analysis of a (13)C2-/(12)C2-dansyl labeled human urine, IsoMS detected 2044 peak pairs, and manual inspection of these peak pairs found 90 false peak pairs, representing a false positive rate of 4.4%. IsoMS for Windows running R is freely available for noncommercial use from www.mycompoundid.org/IsoMS.

Site-specific Orientation of an α-helical Peptide Ovispirin-1 from Isotope Labeled SFG Spectroscopy

Science.gov (United States)

Ding, Bei; Laaser, Jennifer E.; Liu, Yuwei; Wang, Pengrui; Zanni, Martin T.; Chen, Zhan

2013-01-01

Sum-frequency generation (SFG) vibrational spectroscopy is often used to probe the backbone structures and orientations of polypeptides at surfaces. Using the ovispirin-1 polypeptide at the solid/liquid interface of polystyrene, we demonstrate for the first time that SFG can probe the polarization response of a single isotope labeled residue. To interpret the spectral intensities, we simulated the spectra using an excitonic Hamiltonian approach. We show that the polarization dependence of either the label or the unlabeled amide I band alone does not provide sufficient structural constraints to obtain both the tilt and the twist of the ovispirin helix at a solid/liquid interface, but that both can be determined from the polarization dependence of the complete spectrum. For ovispirin, the detailed analysis of the polarized SFG experimental data shows that the helix axis is tilted at roughly 138 degrees from the surface normal, and the transition dipole of the isotope labeled C=O group is tilted at 23 degrees from the surface normal, with the hydrophobic region facing the polystyrene surface. We further demonstrated that the Hamiltonian approach is able to address the coupling effect and the structural disorder. For comparison, we also collected the FTIR spectrum of ovispirin under similar conditions, which reveals the enhanced sensitivity of SFG for structural studies of single monolayer peptide surfaces. Our study provides insight into how structural and environmental effects appear in SFG spectra of the amide I band and establishes that SFG of isotope labeled peptides will be a powerful technique for elucidating secondary structures with residue-by-residue resolution. PMID:24228619

Site-specific orientation of an α-helical peptide ovispirin-1 from isotope-labeled SFG spectroscopy.

Science.gov (United States)

Ding, Bei; Laaser, Jennifer E; Liu, Yuwei; Wang, Pengrui; Zanni, Martin T; Chen, Zhan

2013-11-27

Sum-frequency generation (SFG) vibrational spectroscopy is often used to probe the backbone structures and orientations of polypeptides at surfaces. Using the ovispirin-1 polypeptide at the solid/liquid interface of polystyrene, we demonstrate for the first time that SFG can probe the polarization response of a single-isotope-labeled residue. To interpret the spectral intensities, we simulated the spectra using an excitonic Hamiltonian approach. We show that the polarization dependence of either the label or the unlabeled amide I band alone does not provide sufficient structural constraints to obtain both the tilt and the twist of the ovispirin helix at a solid/liquid interface, but that both can be determined from the polarization dependence of the complete spectrum. For ovispirin, the detailed analysis of the polarized SFG experimental data shows that the helix axis is tilted at roughly 138° from the surface normal, and the transition dipole of the isotope-labeled C═O group is tilted at 23° from the surface normal, with the hydrophobic region facing the polystyrene surface. We further demonstrate that the Hamiltonian approach is able to address the coupling effect and the structural disorder. For comparison, we also collected the FTIR spectrum of ovispirin under similar conditions, which reveals the enhanced sensitivity of SFG for structural studies of single monolayer peptide surfaces. Our study provides insight into how structural and environmental effects appear in SFG spectra of the amide I band and establishes that SFG of isotope-labeled peptides will be a powerful technique for elucidating secondary structures with residue-by-residue resolution.

Quantification of isotope-labelled and unlabelled folates in plasma, ileostomy and food samples.

Science.gov (United States)

Büttner, Barbara E; Öhrvik, Veronica E; Witthöft, Cornelia M; Rychlik, Michael

2011-01-01

New stable isotope dilution assays were developed for the simultaneous quantitation of [(13)C(5)]-labelled and unlabelled 5-methyltetrahydrofolic acid, 5-formyltetrahydrofolic acid, folic acid along with unlabelled tetrahydrofolic acid and 10-formylfolic acid in clinical samples deriving from human bioavailability studies, i.e. plasma, ileostomy samples, and food. The methods were based on clean-up by strong anion exchange followed by LC-MS/MS detection. Deuterated analogues of the folates were applied as the internal standards in the stable isotope dilution assays. Assay sensitivity was sufficient to detect all relevant folates in the respective samples as their limits of detection were below 0.62 nmol/L in plasma and below 0.73 μg/100 g in food or ileostomy samples. Quantification of the [(13)C(5)]-label in clinical samples offers the possibility to differentiate between folate from endogenous body pools and the administered dose when executing bioavailability trials.

Temperature-induced strain and doping in monolayer and bilayer isotopically labeled graphene

Czech Academy of Sciences Publication Activity Database

Verhagen, Timotheus; Drogowska, Karolina; Kalbáč, Martin; Vejpravová, Jana

2015-01-01

Roč. 92, č. 12 (2015), "125437-1"-"125437-9" ISSN 1098-0121 R&D Projects: GA ČR GA15-02196S; GA MŠk LL1301 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : isotopically labeled graphene * temperature dependence * Raman spectroscopy * phonons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

Determination of boron isotope ratios by high-resolution continuum source molecular absorption spectrometry using graphite furnace vaporizers

Science.gov (United States)

Abad, Carlos; Florek, Stefan; Becker-Ross, Helmut; Huang, Mao-Dong; Heinrich, Hans-Joachim; Recknagel, Sebastian; Vogl, Jochen; Jakubowski, Norbert; Panne, Ulrich

2017-10-01

Boron isotope amount ratios n(10B)/n(11B) have been determined by monitoring the absorption spectrum of boron monohydride (BH) in a graphite furnace using high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Bands (0 → 0) and (1 → 1) for the electronic transition X1Σ+ → A1Π were evaluated around wavelengths 433.1 nm and 437.1 nm respectively. Clean and free of memory effect molecular spectra of BH were recorded. In order to eliminate the memory effect of boron, a combination of 2% (v/v) hydrogen gas in argon and 1% trifluoromethane in argon, an acid solution of calcium chloride and mannitol as chemical modifiers was used. Partial least square regression (PLS) for analysis of samples and reference materials were applied. For this, a spectral library with different isotopes ratios for PLS regression was built. Results obtained around the 433.1 nm and 437.1 nm spectral regions are metrologically compatible with those reported by mass spectrometric methods. Moreover, for the evaluated region of 437 nm, an accuracy of 0.15‰ is obtained as the average deviation from the isotope reference materials. Expanded uncertainties with a coverage factor of k = 2 range between 0.15 and 0.44‰. This accuracy and precision are compatible with those obtained by mass spectrometry for boron isotope ratio measurements.

A general procedure for isotopic (deuterium) labelling of non-steroidal antiinflammatory 2-arylpropionic acids

International Nuclear Information System (INIS)

Castell, J.V.; Martinez, L.A.; Universidad Politecnica de Valencia; Miranda, M.A.; Tarrega, Pilar

1994-01-01

Alkaline treatment of nonsteroidal antiinflammatory 2-arylpropionic acids in deuterium oxide led in all cases to isotopic exchange of the proton located at the α-position of the side chain. Monodeuteration was observed in the case of carprofen, ibuprofen, ketoprofen, fenoprofen, flurbiprofen and naproxen. Additional exchange of one or two protons of the heterocyclic ring occurred in indoprofen, suprofen and tiaprofenic acid. The isotopic labelling survived under the conditions required to perform in vitro photoallergic studies (photolysis in non-deuterated aqueous media). (Author)

A general procedure for isotopic (deuterium) labelling of non-steroidal antiinflammatory 2-arylpropionic acids

Energy Technology Data Exchange (ETDEWEB)

Castell, J.V. (Valencia Univ. Hospital (Spain). Centro de Investigacion); Martinez, L.A. (Valencia Univ. Hospital (Spain). Centro de Investigacion Universidad Politecnica de Valencia (Spain). Dept. de Quimica); Miranda, M.A.; Tarrega, Pilar (Universidad Politecnica de Valencia (Spain). Dept. de Quimica)

1994-01-01

Alkaline treatment of nonsteroidal antiinflammatory 2-arylpropionic acids in deuterium oxide led in all cases to isotopic exchange of the proton located at the [alpha]-position of the side chain. Monodeuteration was observed in the case of carprofen, ibuprofen, ketoprofen, fenoprofen, flurbiprofen and naproxen. Additional exchange of one or two protons of the heterocyclic ring occurred in indoprofen, suprofen and tiaprofenic acid. The isotopic labelling survived under the conditions required to perform in vitro photoallergic studies (photolysis in non-deuterated aqueous media). (Author).

UNiquant, a Program for Quantitative Proteomics Analysis Using Stable Isotope Labeling

Energy Technology Data Exchange (ETDEWEB)

Huang, Xin; Tolmachev, Aleksey V.; Shen, Yulei; Liu, Miao; Huang, Lin; Zhang, Zhixin; Anderson, Gordon A.; Smith, Richard D.; Chan, Wing C.; Hinrichs, Steven; Fu, Kai; Ding, Shi-Jian

2011-03-04

We present UNiquant, a new software program for analyzing stable isotope labeling (SIL) based quantitative proteomics data. UNiquant surpassed the performance of two other platforms, MaxQuant and Mascot Distiller, using complex proteome mixtures having either known or unknown heavy/light ratios. UNiquant is compatible with a broad spectrum of search engines and SIL methods, providing outstanding peptide pair identification and accurate measurement of the relative peptide/protein abundance.

Sequencing of Isotope-Labeled Small RNA Using Femtosecond Laser Ablation Time-of-Flight Mass Spectrometry

Science.gov (United States)

Kurata-Nishimura, Mizuki; Ando, Yoshinari; Kobayashi, Tohru; Matsuo, Yukari; Suzuki, Harukazu; Hayashizaki, Yoshihide; Kawai, Jun

2010-04-01

A novel method for the analysis of sequences of small RNAs using nucleotide triphosphates labeled with stable isotopes has been developed using time-of-flight mass spectroscopy combined with femtosecond laser ablation (fsLA-TOF-MS). Small RNAs synthesized with nucleotides enriched in 13C and 15N were efficiently atomized and ionized by single-shot fsLA and the isotope ratios 13C/12C and 15N/14N were evaluated using the TOF-MS method. By comparing the isotope ratios among four different configurations, the number of nucleotide contents of the control RNA sample were successfully reproduced.

Growth and characterization of stoichiometric BCN films on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Mannan, Md. Abdul, E-mail: amannan75@yahoo.co [Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Synchrotron Radiation Research Unit, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Noguchi, Hideyuki; Kida, Tetsuya; Nagano, Masamitsu [Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo, Saga 840-8502 (Japan); Hirao, Norie; Baba, Yuji [Synchrotron Radiation Research Unit, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

2010-05-31

Hexagonal boron carbonitride (h-BCN) hybrid films have been synthesized on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane as a single-source molecular precursor. The films were characterized by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopic measurements. XPS measurement showed that the B atoms were bonded to C and N atoms to form the sp{sup 2}-B-C-N atomic hybrid chemical environment. The atomic composition estimated from the XPS of the typical sample was found to be almost B{sub 1}C{sub 1}N{sub 1}. NEXAFS spectra of the B K-edge and the N K-edge had the peaks due to the {pi}* and {sigma}* resonances of sp{sup 2} hybrid orbitals implying the existence of the sp{sup 2} hybrid configurations of h-BCN around the B atoms. The G band at 1592 and D band at 1352 cm{sup -1} in the Raman spectra also suggested the presence of the graphite-like sp{sup 2}-B-C-N atomic hybrid bonds. The films consisted of micrometer scale crystalline structure of around 10 {mu}m thick has been confirmed by the field emission scanning electron microscopy.

The method for production of high purity carrier free ortophosphoric acid labeled with isotopes Phosphorus-32 and Phosphorus-33

International Nuclear Information System (INIS)

Abdukayumov, M.N.; Abdusalyamov, A.N.; Chistyakov, P.G.; Yuldashev, B.S.

2001-01-01

Extensive application for various radioactive isotopes was found in an extremity of the 20-Th century in a science and production. Labeled compounds are used with growing effectiveness in a molecular biology, gene engineering, medicine and other areas. Phosphorus-32 and Phosphorus-33 isotopes as a different labeled compounds that are used mainly in molecular biology are produced at the Radiopreparat enterprise of the Institute of Nuclear Physics of Academy of Sciences of Uzbekistan Republic. The quality of labeled preparations is very high. The specifications for above mentioned preparations corresponds to demands most of customers in different countries. P-32 or P-33 labeled orthophosphoric acid has high radiochemical purity (more than 99 %) and specific radioactivity close to theoretical. Orthophosphoric acid prepared by the described above method has radiochemical purity about 95 % and output of the target product 99%

A Neutron-Diffraction Study of the Solid Layers at the Liquid Solid Boundary in 4He-Films Adsorbed on Graphite

DEFF Research Database (Denmark)

da Costa Carneiro, Kim; Passell, L.; Thomlinson, W.

1981-01-01

A neutron scattering study of the structure of 4He films adsorbed on graphite is reported. Diffraction from helium monolayers at a temperature of 1.2K shows the formation of an incommensurate, triangular-lattice solid of high density. As the coverage is increased above two layers, the diffraction...

Differential Isotope Labeling of Glycopeptides for Accurate Determination of Differences in Site-Specific Glycosylation.

Science.gov (United States)

Pabst, Martin; Benešová, Iva; Fagerer, Stephan R; Jacobsen, Mathias; Eyer, Klaus; Schmidt, Gregor; Steinhoff, Robert; Krismer, Jasmin; Wahl, Fabian; Preisler, Jan; Zenobi, Renato

2016-01-04

We introduce a stable isotope labeling approach for glycopeptides that allows a specific glycosylation site in a protein to be quantitatively evaluated using mass spectrometry. Succinic anhydride is used to specifically label primary amino groups of the peptide portion of the glycopeptides. The heavy form (D4(13)C4) provides an 8 Da mass increment over the light natural form (H4(12)C4), allowing simultaneous analysis and direct comparison of two glycopeptide profiles in a single MS scan. We have optimized a protocol for an in-solution trypsin digestion, a one-pot labeling procedure, and a post-labeling solid-phase extraction to obtain purified and labeled glycopeptides. We provide the first demonstration of this approach by comparing IgG1 Fc glycopeptides from polyclonal IgG samples with respect to their galactosylation and sialylation patterns using MALDI MS and LC-ESI-MS.

Inhibition of oxidation in nuclear graphite

International Nuclear Information System (INIS)

Winston, Philip L.; Sterbentz, James W.; Windes, William E.

2015-01-01

Graphite is a fundamental material of high-temperature gas-cooled nuclear reactors, providing both structure and neutron moderation. Its high thermal conductivity, chemical inertness, thermal heat capacity, and high thermal structural stability under normal and off-normal conditions contribute to the inherent safety of these reactor designs. One of the primary safety issues for a high-temperature graphite reactor core is the possibility of rapid oxidation of the carbon structure during an off-normal design basis event where an oxidising atmosphere (air ingress) can be introduced to the hot core. Although the current Generation IV high-temperature reactor designs attempt to mitigate any damage caused by a postulated air ingress event, the use of graphite components that inhibit oxidation is a logical step to increase the safety of these reactors. Recent experimental studies of graphite containing between 5.5 and 7 wt% boron carbide (B 4 C) indicate that oxidation is dramatically reduced even at prolonged exposures at temperatures up to 900 deg. C. The proposed addition of B 4 C to graphite components in the nuclear core would necessarily be enriched in B-11 isotope in order to minimise B-10 neutron absorption and graphite swelling. The enriched boron can be added to the graphite during billet fabrication. Experimental oxidation rate results and potential applications for borated graphite in nuclear reactor components will be discussed. (authors)

Isotopes in agriculture

International Nuclear Information System (INIS)

1983-01-01

Part 1: The stable isotope of nitrogen 15N has become widely used as tracer in agriculture, medicine and biology research. The film gives an overview of the sample preparation and analytical procedures followed in the analysis of the nitrogen isotopic composition (14N/15N ratio) by optical emission spectrometry at the Seibersdorf Laboratory. The subsampling of plant material and the several steps of chemical pretreatment such as Kjeldahl digestion, distillation, titration and adjustment of the proper N concentration in the extract are demonstrated. The preparation of the discharge tubes is shown in detail. Final measurement of the 14N/15N ratio is carried out with the NOI-5 and JASCO emission spectrometers. Part 2: This training film deals with the use of 32P-labelled materials in field and greenhouse experimentation in soil-plant relationships studies. All technical aspects, including safe handling and radiation protection procedures to be considered in the layout and harvesting of field experiments are documented in detail. Procedures followed up in the evaluation of P fertilizers such as rock phosphates under greenhouse conditions are described. Several soil injection techniques available for determination of the root activity pattern of trees are shown

Trace, isotopic analysis of micron-sized grains -- Mo, Zr analysis of stardust (SiC and graphite grains).

Energy Technology Data Exchange (ETDEWEB)

Pellin, M. J.; Nicolussi, G. K.

1998-02-19

Secondary Neutral Mass Spectrometry using resonant laser ionization can provide for both high useful yields and high discrimination while maintaining high lateral and depth resolutions. An example of the power of the method is measurement of the isotopic composition of Mo and Zr in 1-5 {micro}m presolar SiC and graphite grains isolated from the Murchison CM2 meteorite for the first time. These grains have survived the formation of the Solar System and isotopic analysis reveals a record of the stellar nucleosynthesis present during their formation. Mo and Zr, though present at less than 10 ppm in some grains, are particularly useful in that among their isotopes are members that can only be formed by distinct nucleosynthetic processes known as s-, p-, and r-process. Successful isotopic analysis of these elements requires both high selectivity (since these are trace elements) and high efficiency (since the total number of atoms available are limited). Resonant Ionization Spectroscopy is particularly useful and flexible in this application. While the sensitivity of this t.edmique has often been reported in the past, we focus hereon the very low noise properties of the technique. We further demonstrate the efficacy of noise removal by two complimentary methods. First we use the resonant nature of the signal to subtract background signal. Second we demonstrate that by choosing the appropriate resonance scheme background can often be dramatically reduced.

Reconstitution of Nucleosomes with Differentially Isotope-labeled Sister Histones.

Science.gov (United States)

Liokatis, Stamatios

2017-03-26

Asymmetrically modified nucleosomes contain the two copies of a histone (sister histones) decorated with distinct sets of Post-translational Modifications (PTMs). They are newly identified species with unknown means of establishment and functional implications. Current analytical methods are inadequate to detect the copy-specific occurrence of PTMs on the nucleosomal sister histones. This protocol presents a biochemical method for the in vitro reconstitution of nucleosomes containing differentially isotope-labeled sister histones. The generated complex can be also asymmetrically modified, after including a premodified histone pool during refolding of histone subcomplexes. These asymmetric nucleosome preparations can be readily reacted with histone-modifying enzymes to study modification cross-talk mechanisms imposed by the asymmetrically pre-incorporated PTM using nuclear magnetic resonance (NMR) spectroscopy. Particularly, the modification reactions in real-time can be mapped independently on the two sister histones by performing different types of NMR correlation experiments, tailored for the respective isotope type. This methodology provides the means to study crosstalk mechanisms that contribute to the formation and propagation of asymmetric PTM patterns on nucleosomal complexes.

Graphite as an indicator of contact influence of Western Keivy alkaline granite intrusion, the Kola Peninsula

Directory of Open Access Journals (Sweden)

Fomina E. N.

2017-03-01

Full Text Available The results of complex petro-mineragraphic, Raman and isotope- geochemical study of three types of graphite- bearing rocks circulated at different distances from the alkaline granites: (1 kyanite schists of Bolshiye Keivy, sampled at a considerable distance from a contact with alkaline gran ites; (2 sillimanite schists, sampled close to the contact, and (3 silexites, located in the inner part of th e alkaline granite massif Western Keivy have been presented. Five morphogenetic types of graphite have been revealed in the rocks under consideration: fine- grained Gr-1, intergranular Gr-2, nest-shaped Gr-3, vein Gr- 4 and spherulitic Gr-5. Current study demonstrates that these five types of graphite distinctly vary not only i n morphology, but also in temperature of crystallization, as determined by RSCM-Raman geothermometer, and in carbon isotop e composition. The most likely source for the anomalous "light" graphite Gr-1 and Gr-2 [δ 13 C(PDB = −43...−45 ‰] from kyanite schists is a water- methane fluid originating from sedimentary rocks with org anic compounds. The carbon of graphite Gr-5 of the silexites selected at the inner part of alkaline granite massif West ern Keivy, on the contrary, proved to be most "heavy" [δ 13 C(PDB = −8 ‰], which indicates its origin from the lower crustal or mantle carbon dioxide fluid. Thus, carbon extracted into the rocks of Keivy structure from at least two contrasting isotope sources. Graphite Gr-3, that makes up the bulk of graphite of exocontact sil limanite schists, is also isotopically light, but not anomalously [δ 13 C(PDB = −17...−28 ‰]. The crystallization temperature of the gi ven graphite (435−520 ºC, and its structural relationships with other minerals of th e rock evidence of its synmetamorphic origin. The presence of veinlets of isotopically heavy [δ 13 C(PDB = −10 ‰...−11 ‰] high-temperature (570−670 ºC graphite intersecting minerals of the metamorphic paragenesis (i

Multiferroic BiFeO3 thin films and nanodots grown on highly oriented pyrolytic graphite substrates

Science.gov (United States)

Shin, Hyun Wook; Son, Jong Yeog

2017-12-01

Multiferroic BiFeO3 (BFO) thin films and nanodots are deposited on highly oriented pyrolytic graphite (HOPG) substrates via a pulsed laser deposition technique, where the HOPG surface has a honeycomb lattice structure made of carbon atoms, similar to graphene. A graphene/BFO/HOPG capacitor exhibited multiferroic properties, namely ferroelectricity (a residual polarization of 26.8 μC/cm2) and ferromagnetism (a residual magnetization of 1.1 × 10-5 emu). The BFO thin film had high domain wall energies and demonstrated switching time of approximately 82 ns. An 8-nm BFO nanodot showed a typical piezoelectric hysteresis loop with an effective residual piezoelectric constant of approximately 110 pm/V and exhibited two clearly separated current curves depending on the ferroelectric polarization direction.

The LB Films of Dansyl Chloride Labeled Octadecylamine and Its Fluorescence Lifetime

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) in order to simplify and understand the LB films of fluorescent probe labeling proteins.Its monolayer and multilayers in the absence and presence of stearic acid were deposited by LB technique.Fluorescence spectra and lifetimes of the fluorescent products were studied to elucidate the microenvironment of molecules in the LB films.

Accurate and sensitive determination of molar fractions of "1"3C-Labeled intracellular metabolites in cell cultures grown in the presence of isotopically-labeled glucose

International Nuclear Information System (INIS)

Fernández-Fernández, Mario; Rodríguez-González, Pablo; Hevia Sánchez, David; González-Menéndez, Pedro; Sainz Menéndez, Rosa M.; García Alonso, J. Ignacio

2017-01-01

This work describes a methodology based on multiple linear regression and GC-MS for the determination of molar fractions of isotopically-labeled intracellular metabolites in cell cultures. Novel aspects of this work are: i) the calculation of theoretical isotopic distributions of the different isotopologues from an experimentally measured value of % 13C enrichment of the labeled precursor ii) the calculation of the contribution of lack of mass resolution of the mass spectrometer and different fragmentation mechanism such as the loss or gain of hydrogen atoms in the EI source to measure the purity of the selected cluster for each metabolite and iii) the validation of the methodology not only by the analysis of gravimetrically prepared mixtures of isotopologues but also by the comparison of the obtained molar fractions with experimental values obtained by GC-Combustion-IRMS based on "1"3C/"1"2C isotope ratio measurements. The method is able to measure molar fractions for twenty-eight intracellular metabolites derived from glucose metabolism in cell cultures grown in the presence of "1"3C-labeled Glucose. The validation strategies demonstrate a satisfactory accuracy and precision of the proposed procedure. Also, our results show that the minimum value of "1"3C incorporation that can be accurately quantified is significantly influenced by the calculation of the spectral purity of the measured cluster and the number of "1"3C atoms of the labeled precursor. The proposed procedure was able to accurately quantify gravimetrically prepared mixtures of natural and labeled glucose molar fractions of 0.07% and mixtures of natural and labeled glycine at molar fractions down to 0.7%. The method was applied to initial studies of glucose metabolism of different prostate cancer cell lines. - Highlights: • Determination of molar fractions of "1"3C-labeled metabolites in cell cultures. • The method is based on multiple linear regression and GC-MS. • Validation of the method by

Accurate and sensitive determination of molar fractions of {sup 13}C-Labeled intracellular metabolites in cell cultures grown in the presence of isotopically-labeled glucose

Energy Technology Data Exchange (ETDEWEB)

Fernández-Fernández, Mario [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo (Spain); Rodríguez-González, Pablo, E-mail: rodriguezpablo@uniovi.es [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo (Spain); Hevia Sánchez, David; González-Menéndez, Pedro; Sainz Menéndez, Rosa M. [University Institute of Oncology (IUOPA), University of Oviedo, Julián Clavería 6, 33006 Oviedo (Spain); García Alonso, J. Ignacio [Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo (Spain)

2017-05-29

This work describes a methodology based on multiple linear regression and GC-MS for the determination of molar fractions of isotopically-labeled intracellular metabolites in cell cultures. Novel aspects of this work are: i) the calculation of theoretical isotopic distributions of the different isotopologues from an experimentally measured value of % 13C enrichment of the labeled precursor ii) the calculation of the contribution of lack of mass resolution of the mass spectrometer and different fragmentation mechanism such as the loss or gain of hydrogen atoms in the EI source to measure the purity of the selected cluster for each metabolite and iii) the validation of the methodology not only by the analysis of gravimetrically prepared mixtures of isotopologues but also by the comparison of the obtained molar fractions with experimental values obtained by GC-Combustion-IRMS based on {sup 13}C/{sup 12}C isotope ratio measurements. The method is able to measure molar fractions for twenty-eight intracellular metabolites derived from glucose metabolism in cell cultures grown in the presence of {sup 13}C-labeled Glucose. The validation strategies demonstrate a satisfactory accuracy and precision of the proposed procedure. Also, our results show that the minimum value of {sup 13}C incorporation that can be accurately quantified is significantly influenced by the calculation of the spectral purity of the measured cluster and the number of {sup 13}C atoms of the labeled precursor. The proposed procedure was able to accurately quantify gravimetrically prepared mixtures of natural and labeled glucose molar fractions of 0.07% and mixtures of natural and labeled glycine at molar fractions down to 0.7%. The method was applied to initial studies of glucose metabolism of different prostate cancer cell lines. - Highlights: • Determination of molar fractions of {sup 13}C-labeled metabolites in cell cultures. • The method is based on multiple linear regression and GC-MS. �

Isotope coded protein labeling coupled immunoprecipitation (ICPL-IP): a novel approach for quantitative protein complex analysis from native tissue.

Science.gov (United States)

Vogt, Andreas; Fuerholzner, Bettina; Kinkl, Norbert; Boldt, Karsten; Ueffing, Marius

2013-05-01

High confidence definition of protein interactions is an important objective toward the understanding of biological systems. Isotope labeling in combination with affinity-based isolation of protein complexes has increased in accuracy and reproducibility, yet, larger organisms--including humans--are hardly accessible to metabolic labeling and thus, a major limitation has been its restriction to small animals, cell lines, and yeast. As composition as well as the stoichiometry of protein complexes can significantly differ in primary tissues, there is a great demand for methods capable to combine the selectivity of affinity-based isolation as well as the accuracy and reproducibility of isotope-based labeling with its application toward analysis of protein interactions from intact tissue. Toward this goal, we combined isotope coded protein labeling (ICPL)(1) with immunoprecipitation (IP) and quantitative mass spectrometry (MS). ICPL-IP allows sensitive and accurate analysis of protein interactions from primary tissue. We applied ICPL-IP to immuno-isolate protein complexes from bovine retinal tissue. Protein complexes of immunoprecipitated β-tubulin, a highly abundant protein with known interactors as well as the lowly expressed small GTPase RhoA were analyzed. The results of both analyses demonstrate sensitive and selective identification of known as well as new protein interactions by our method.

Isotope Coded Protein Labeling Coupled Immunoprecipitation (ICPL-IP): A Novel Approach for Quantitative Protein Complex Analysis From Native Tissue*

Science.gov (United States)

Vogt, Andreas; Fuerholzner, Bettina; Kinkl, Norbert; Boldt, Karsten; Ueffing, Marius

2013-01-01

High confidence definition of protein interactions is an important objective toward the understanding of biological systems. Isotope labeling in combination with affinity-based isolation of protein complexes has increased in accuracy and reproducibility, yet, larger organisms—including humans—are hardly accessible to metabolic labeling and thus, a major limitation has been its restriction to small animals, cell lines, and yeast. As composition as well as the stoichiometry of protein complexes can significantly differ in primary tissues, there is a great demand for methods capable to combine the selectivity of affinity-based isolation as well as the accuracy and reproducibility of isotope-based labeling with its application toward analysis of protein interactions from intact tissue. Toward this goal, we combined isotope coded protein labeling (ICPL)1 with immunoprecipitation (IP) and quantitative mass spectrometry (MS). ICPL-IP allows sensitive and accurate analysis of protein interactions from primary tissue. We applied ICPL-IP to immuno-isolate protein complexes from bovine retinal tissue. Protein complexes of immunoprecipitated β-tubulin, a highly abundant protein with known interactors as well as the lowly expressed small GTPase RhoA were analyzed. The results of both analyses demonstrate sensitive and selective identification of known as well as new protein interactions by our method. PMID:23268931

Auto-inducing media for uniform isotope labeling of proteins with {sup 15}N, {sup 13}C and {sup 2}H

Energy Technology Data Exchange (ETDEWEB)

Guthertz, Nicolas [Institute of Cancer Research, Division of Structural Biology (United Kingdom); Klopp, Julia; Winterhalter, Aurélie; Fernández, César; Gossert, Alvar D., E-mail: alvar.gossert@novartis.com [Novartis Institutes for BioMedical Research (Switzerland)

2015-06-15

Auto-inducing media for protein expression offer many advantages like robust reproducibility, high yields of soluble protein and much reduced workload. Here, an auto-inducing medium for uniform isotope labelling of proteins with {sup 15}N, {sup 13}C and/or {sup 2}H in E. coli is presented. So far, auto-inducing media have not found widespread application in the NMR field, because of the prohibitively high cost of labeled lactose, which is an essential ingredient of such media. Here, we propose using lactose that is only selectively labeled on the glucose moiety. It can be synthesized from inexpensive and readily available substrates: labeled glucose and unlabeled activated galactose. With this approach, uniformly isotope labeled proteins were expressed in unattended auto-inducing cultures with incorporation of {sup 13}C, {sup 15}N of 96.6 % and {sup 2}H, {sup 15}N of 98.8 %. With the present protocol, the NMR community could profit from the many advantages that auto-inducing media offer.

Quantitative proteomics by amino acid labeling in C. elegans

DEFF Research Database (Denmark)

Fredens, Julius; Engholm-Keller, Kasper; Giessing, Anders

2011-01-01

We demonstrate labeling of Caenorhabditis elegans with heavy isotope-labeled lysine by feeding them with heavy isotope-labeled Escherichia coli. Using heavy isotope-labeled worms and quantitative proteomics methods, we identified several proteins that are regulated in response to loss or RNAi-med......-mediated knockdown of the nuclear hormone receptor 49 in C. elegans. The combined use of quantitative proteomics and selective gene knockdown is a powerful tool for C. elegans biology.......We demonstrate labeling of Caenorhabditis elegans with heavy isotope-labeled lysine by feeding them with heavy isotope-labeled Escherichia coli. Using heavy isotope-labeled worms and quantitative proteomics methods, we identified several proteins that are regulated in response to loss or RNAi...

Metabolic flux analysis of the phenylpropanoid pathway in wound-healing potato tuber tissue using stable isotope-labeled tracer and LC-MS spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Matsuda, Fumio; Morino, Keiko; Miyashita, Masahiro; Miyagawa, Hisashi [Kyoto Univ. (Japan). Department of Agriculture

2003-05-01

The metabolic flux of two phenylpropanoid metabolites, N-p-coumaroyloctopamine (p-CO) and chlorogenic acid (CGA), in the wound-healing potato tuber tissue was quantitatively analyzed by a newly developed method based upon the tracer experiment using stable isotope-labeled compounds and LC-MS. Tuber disks were treated with aqueous solution of L-phenyl-d{sub 5}-alanine, and the change in the ratio of stable isotope-labeled compound to non-labeled (isotope abundance) was monitored for p-CO and CGA in the tissue extract by LC-MS. The time-dependent change in the isotope abundance of each metabolite was fitted to an equation that was derived from the formation and conversion kinetics of each compound. Good correlations were obtained between the observed and calculated isotope abundances for both p-CO and CGA. The rates of p-CO formation and conversion (i.e. fluxes) were 1.15 and 0.96 nmol (g FW){sup -1}h{sup -1}, respectively, and for CGA, the rates 4.63 and 0.42 nmol (g FW){sup -1}h{sup -1}, respectively. This analysis enabled a direct comparison of the biosynthetic activity between these two compounds. (author)

Isotopic labeling study of oxygen diffusion in amorphous LaScO3 high-κ films on Si(100) and its effects on the electrical characteristics

International Nuclear Information System (INIS)

Lopes, J.M.J.; Littmark, U.; Roeckerath, M.; Durgun Oezben, E.; Lenk, S.; Schubert, J.; Mantl, S.; Breuer, U.; Besmehn, A.; Staerk, A.; Grande, P.L.; Sortica, M.A.; Radtke, C.

2009-01-01

The influence of post-deposition oxygen anneals on the properties of amorphous LaScO 3 films on Si(100) is reported. The use of an isotopically ( 18 O 2 ) enriched atmosphere allowed to investigate the 16 O- 18 O exchange and the oxygen diffusion across the dielectric layer. Such effects are connected to the formation of an interfacial layer. Oxygen annealing leads to nearly ideal capacitance-voltage curves, lower leakage currents and interface trap densities, as well as to κ-values up to 33 for the LaScO 3 films. These results are attributed to the suppression of oxygen-related trap centers and the achievement of a stoichiometric oxygen content. (orig.)

Synthesis of stable isotopically labeled peptides with filter-assisted enzymatic labeling for the diagnosis of hepatitis B virus infection utilizing mass spectrometry-based proteomics strategy

International Nuclear Information System (INIS)

Tsai, Hsing-Fen; Hsiao, He-Hsuan

2017-01-01

A facile method for the preparation of stable isotopically labeled peptides was developed by means of filter-assisted tryptic "1"6O/"1"8O water labeling, which could be directly applied to the determination of hepatitis B virus infection from human serum with tandem mass spectrometry. Tryptic peptides of hepatitis B surface antigen or hepatitis B e antigen from different subtypes of hepatitis B virus were synthesized with traditional solid-phase peptide synthesis as potential biomarkers. Trypsin catalyzed oxygen-18 exchange at their amidated c-terminus of arginine or lysine residue. The protease catalyzed oxygen-18 to oxygen-16 back exchange reaction was eliminated due to the complete removal of trypsin by the centrifugal filter containing a thin membrane associated with molecular weight cut-off of 10 KDa. The synthetic isotopic peptides were spiked into trichloroacetic acid/acetone precipitated human serum as internal standards and were selectively detected with multiplexed parallel reaction monitoring on a hybrid quadrupole-orbitrap mass spectrometer. The limit of detection for all synthetic peptides were in the range of 0.09 fmol–1.13 fmol. The results indicated that the peptide YLWEWASVR derived from hepatitis B surface antigen was quantified approximately 200 fmol per μl serum and may serve as a diagnostic biomarker for the detection of hepatitis B virus infected disease. - Highlights: • Facile synthesis of an inexpensive and highly reproducible stable isotopically labeled peptides. • Complete incorporation of two "1"8O atoms into synthesized peptides with filter-assisted enzymatic labeling. • Targeted analysis with parallel reaction monitoring assay for the disease diagnosis.

Synthesis of stable isotopically labeled peptides with filter-assisted enzymatic labeling for the diagnosis of hepatitis B virus infection utilizing mass spectrometry-based proteomics strategy

Energy Technology Data Exchange (ETDEWEB)

Tsai, Hsing-Fen; Hsiao, He-Hsuan, E-mail: hhhsiao@dragon.nchu.edu.tw

2017-03-01

A facile method for the preparation of stable isotopically labeled peptides was developed by means of filter-assisted tryptic {sup 16}O/{sup 18}O water labeling, which could be directly applied to the determination of hepatitis B virus infection from human serum with tandem mass spectrometry. Tryptic peptides of hepatitis B surface antigen or hepatitis B e antigen from different subtypes of hepatitis B virus were synthesized with traditional solid-phase peptide synthesis as potential biomarkers. Trypsin catalyzed oxygen-18 exchange at their amidated c-terminus of arginine or lysine residue. The protease catalyzed oxygen-18 to oxygen-16 back exchange reaction was eliminated due to the complete removal of trypsin by the centrifugal filter containing a thin membrane associated with molecular weight cut-off of 10 KDa. The synthetic isotopic peptides were spiked into trichloroacetic acid/acetone precipitated human serum as internal standards and were selectively detected with multiplexed parallel reaction monitoring on a hybrid quadrupole-orbitrap mass spectrometer. The limit of detection for all synthetic peptides were in the range of 0.09 fmol–1.13 fmol. The results indicated that the peptide YLWEWASVR derived from hepatitis B surface antigen was quantified approximately 200 fmol per μl serum and may serve as a diagnostic biomarker for the detection of hepatitis B virus infected disease. - Highlights: • Facile synthesis of an inexpensive and highly reproducible stable isotopically labeled peptides. • Complete incorporation of two {sup 18}O atoms into synthesized peptides with filter-assisted enzymatic labeling. • Targeted analysis with parallel reaction monitoring assay for the disease diagnosis.

Electropolymerization of 3-aminophenol on carbon graphite surface: Electric and morphologic properties

Energy Technology Data Exchange (ETDEWEB)

Franco, Diego L.; Afonso, Andre S.; Vieira, Sabrina N.; Ferreira, Lucas F. [Institute of Chemistry, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, 38400-902 Uberlandia (Brazil); Goncalves, Rafael A. [School of Mechanical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, 38400-902 Uberlandia (Brazil); Brito-Madurro, Ana G. [Institute of Chemistry, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, 38400-902 Uberlandia (Brazil); Madurro, Joao M. [Institute of Chemistry, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, 38400-902 Uberlandia (Brazil)], E-mail: jmadurro@ufu.br

2008-02-15

This paper reports the formation of electropolymerized films derived from 3-aminophenol on graphite electrode by cyclic voltammetry, prepared in different pH conditions. With increase of pH values, a shift of the oxidation potential of 3-aminophenol to more cathodic potentials was observed. 3-Aminophenol electrooxidation, in acid and basic media, yielded polymeric films onto graphite surface. In ferrocyanide/ferricyanide solution, the polymer produced in acid medium showed higher electron transfer efficiency. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and FT-IR were used to investigate some properties of the graphite electrode modified with poly(3-aminophenol). Scanning electron microscopy showed that the morphology of the films is strongly dependent on the pH of the electropolymerization medium. FT-IR spectra of polymer films produced for either acid or basic media suggest that the monomer is polymerized by NH{sub 2} group.

Electropolymerization of 3-aminophenol on carbon graphite surface: Electric and morphologic properties

International Nuclear Information System (INIS)

Franco, Diego L.; Afonso, Andre S.; Vieira, Sabrina N.; Ferreira, Lucas F.; Goncalves, Rafael A.; Brito-Madurro, Ana G.; Madurro, Joao M.

2008-01-01

This paper reports the formation of electropolymerized films derived from 3-aminophenol on graphite electrode by cyclic voltammetry, prepared in different pH conditions. With increase of pH values, a shift of the oxidation potential of 3-aminophenol to more cathodic potentials was observed. 3-Aminophenol electrooxidation, in acid and basic media, yielded polymeric films onto graphite surface. In ferrocyanide/ferricyanide solution, the polymer produced in acid medium showed higher electron transfer efficiency. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and FT-IR were used to investigate some properties of the graphite electrode modified with poly(3-aminophenol). Scanning electron microscopy showed that the morphology of the films is strongly dependent on the pH of the electropolymerization medium. FT-IR spectra of polymer films produced for either acid or basic media suggest that the monomer is polymerized by NH 2 group

A discussion of possible mechanisms affecting fission product transport in irradiated and unirradiated nuclear grade graphite

International Nuclear Information System (INIS)

Firth, M.J.

1977-09-01

137 Cs, 85 Sr, and sup(110m)Ag adsorption experiments were conducted on three graphite powders with differing amounts of specific basal and edge surface areas. No direct proportionality was found between the specific amounts of the isotopes adsorbed and either of the surface characteristics. There appears to be some correlation with the specific basal surface area despite the fact that each isotope behaves differently. Factors that might influence the adsorption behaviour of Cs and Ag during reactor irradiation and heat treatment of nuclear grade graphites are discussed. These include the form of Cs with the graphite surface. A model based on Cs adsorption at vacancy clusters is used to analyse adsorption experiments. A possible explanation for the behaviour of Ag through the migration of graphite impurities from the bulk of the graphite to the pore surface is also discussed. (author)

Evaluation of the impact of matrix effect on quantification of pesticides in foods by gas chromatography-mass spectrometry using isotope-labeled internal standards.

Science.gov (United States)

Yarita, Takashi; Aoyagi, Yoshie; Otake, Takamitsu

2015-05-29

The impact of the matrix effect in GC-MS quantification of pesticides in food using the corresponding isotope-labeled internal standards was evaluated. A spike-and-recovery study of nine target pesticides was first conducted using paste samples of corn, green soybean, carrot, and pumpkin. The observed analytical values using isotope-labeled internal standards were more accurate for most target pesticides than that obtained using the external calibration method, but were still biased from the spiked concentrations when a matrix-free calibration solution was used for calibration. The respective calibration curves for each target pesticide were also prepared using matrix-free calibration solutions and matrix-matched calibration solutions with blank soybean extract. The intensity ratio of the peaks of most target pesticides to that of the corresponding isotope-labeled internal standards was influenced by the presence of the matrix in the calibration solution; therefore, the observed slope varied. The ratio was also influenced by the type of injection method (splitless or on-column). These results indicated that matrix-matching of the calibration solution is required for very accurate quantification, even if isotope-labeled internal standards were used for calibration. Copyright © 2015 Elsevier B.V. All rights reserved.

Isotopes accumulation in the thermal column of TRIGA reactor

International Nuclear Information System (INIS)

Iorgulis, C.; Diaconu, D.; Gugiu, D.; Csaba, R.

2013-01-01

The correlation of impurity observed in the virgin graphite and radionuclide content and activities measured in the irradiated graphite needs to know the irradiated history. This is a challenging process if impurity content and irradiation conditions are not accurately known. This is the case of the irradiated graphite in the thermal column of Institute for Nuclear Research Pitesti (INR)14 MW TRIGA reactor. To overcome incomplete impurity content and the unknown position in the column of the measured irradiated graphite available for characterisation and comparison, a set of preliminary simulations were performed. Following Eu 152 /Eu 154 ration they allowed the estimation of an impurity content and irradiation conditions leading to measured activities. Based on these data the radio-isotope accumulation in different positions in the thermal column was predicted. Modelling performed by INR used advanced prediction packages (e.g. WIMS, MCNP ORIGEN-S from Scale 5) to assess the isotopic content of MTR graphite types with irradiation history specific for a TRIGA research reactor. Some certain calculations points from the column were selected in order to model the burnup and isotopes productions using ORIGEN from SCALE code system. (authors)

Cooperation of CMEA member states in the field of the manufacture and use of stable isotopes and compounds thus labelled

International Nuclear Information System (INIS)

Ertel, G.; Ewald, G.

1977-01-01

The contribution presents a survey of scientific-technical cooperation of CMEA member states in the field of stable isotopes, it deals with the specialization of stable isotope production and compounds thus labelled, and gives the prospects for further development of this cooperation. (HK) [de

Isotope label-aided mass spectrometry reveals the influence of environmental factors on metabolism in single eggs of fruit fly.

Directory of Open Access Journals (Sweden)

Te-Wei Tseng

Full Text Available In order to investigate the influence of light/dark cycle on the biosynthesis of metabolites during oogenesis, here we demonstrate a simple experimental protocol which combines in-vivo isotopic labeling of primary metabolites with mass spectrometric analysis of single eggs of fruit fly (Drosophila melanogaster. First, fruit flies were adapted to light/dark cycle using artificial white light. Second, female flies were incubated with an isotopically labeled sugar ((13C(6-glucose for 12 h--either during the circadian day or the circadian night, at light or at dark. Third, eggs were obtained from the incubated female flies, and analyzed individually by matrix-assisted laser desorption/ionization (MALDI mass spectrometry (MS: this yielded information about the extent of labeling with carbon-13. Since the incorporation of carbon-13 to uridine diphosphate glucose (UDP-glucose in fruit fly eggs is very fast, the labeling of this metabolite was used as an indicator of the biosynthesis of metabolites flies/eggs during 12-h periods, which correspond to circadian day or circadian night. The results reveal that once the flies adapted to the 12-h-light/12-h-dark cycle, the incorporation of carbon-13 to UDP-glucose present in fruit fly eggs was not markedly altered by an acute perturbation to this cycle. This effect may be due to a relationship between biosynthesis of primary metabolites in developing eggs and an alteration to the intake of the labeled substrate - possibly related to the change of the feeding habit. Overall, the study shows the possibility of using MALDI-MS in conjunction with isotopic labeling of small metazoans to unravel the influence of environmental cues on primary metabolism.

Comparison of a Label-Free Quantitative Proteomic Method Based on Peptide Ion Current Area to the Isotope Coded Affinity Tag Method

Directory of Open Access Journals (Sweden)

Young Ah Goo

2008-01-01

Full Text Available Recently, several research groups have published methods for the determination of proteomic expression profiling by mass spectrometry without the use of exogenously added stable isotopes or stable isotope dilution theory. These so-called label-free, methods have the advantage of allowing data on each sample to be acquired independently from all other samples to which they can later be compared in silico for the purpose of measuring changes in protein expression between various biological states. We developed label free software based on direct measurement of peptide ion current area (PICA and compared it to two other methods, a simpler label free method known as spectral counting and the isotope coded affinity tag (ICAT method. Data analysis by these methods of a standard mixture containing proteins of known, but varying, concentrations showed that they performed similarly with a mean squared error of 0.09. Additionally, complex bacterial protein mixtures spiked with known concentrations of standard proteins were analyzed using the PICA label-free method. These results indicated that the PICA method detected all levels of standard spiked proteins at the 90% confidence level in this complex biological sample. This finding confirms that label-free methods, based on direct measurement of the area under a single ion current trace, performed as well as the standard ICAT method. Given the fact that the label-free methods provide ease in experimental design well beyond pair-wise comparison, label-free methods such as our PICA method are well suited for proteomic expression profiling of large numbers of samples as is needed in clinical analysis.

Determining synthesis rates of individual proteins in zebrafish (Danio rerio) with low levels of a stable isotope labelled amino acid.

Science.gov (United States)

Geary, Bethany; Magee, Kieran; Cash, Phillip; Young, Iain S; Whitfield, Phillip D; Doherty, Mary K

2016-05-01

The zebrafish is a powerful model organism for the analysis of human cardiovascular development and disease. Understanding these processes at the protein level not only requires changes in protein concentration to be determined but also the rate at which these changes occur on a protein-by-protein basis. The ability to measure protein synthesis and degradation rates on a proteome-wide scale, using stable isotope labelling in conjunction with mass spectrometry is now a well-established experimental approach. With the advent of more selective and sensitive mass spectrometers, it is possible to accurately measure lower levels of stable isotope incorporation, even when sample is limited. In order to challenge the sensitivity of this approach, we successfully determined the synthesis rates of over 600 proteins from the cardiac muscle of the zebrafish using a diet where either 30% or 50% of the L-leucine was replaced with a stable isotope labelled analogue ([(2) H7 ]L-leucine]. It was possible to extract sufficient protein from individual zebrafish hearts to determine the incorporation rate of the label into hundreds of proteins simultaneously, with the two labelling regimens showing a good correlation of synthesis rates. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isotope analysis of diamond-surface passivation effect of high-temperature H2O-grown atomic layer deposition-Al2O3 films

International Nuclear Information System (INIS)

Hiraiwa, Atsushi; Saito, Tatsuya; Matsumura, Daisuke; Kawarada, Hiroshi

2015-01-01

The Al 2 O 3 film formed using an atomic layer deposition (ALD) method with trimethylaluminum as Al precursor and H 2 O as oxidant at a high temperature (450 °C) effectively passivates the p-type surface conduction (SC) layer specific to a hydrogen-terminated diamond surface, leading to a successful operation of diamond SC field-effect transistors at 400 °C. In order to investigate this excellent passivation effect, we carried out an isotope analysis using D 2 O instead of H 2 O in the ALD and found that the Al 2 O 3 film formed at a conventional temperature (100 °C) incorporates 50 times more CH 3 groups than the high-temperature film. This CH 3 is supposed to dissociate from the film when heated afterwards at a higher temperature (550 °C) and causes peeling patterns on the H-terminated surface. The high-temperature film is free from this problem and has the largest mass density and dielectric constant among those investigated in this study. The isotope analysis also unveiled a relatively active H-exchange reaction between the diamond H-termination and H 2 O oxidant during the high-temperature ALD, the SC still being kept intact. This dynamic and yet steady H termination is realized by the suppressed oxidation due to the endothermic reaction with H 2 O. Additionally, we not only observed the kinetic isotope effect in the form of reduced growth rate of D 2 O-oxidant ALD but found that the mass density and dielectric constant of D 2 O-grown Al 2 O 3 films are smaller than those of H 2 O-grown films. This is a new type of isotope effect, which is not caused by the presence of isotopes in the films unlike the traditional isotope effects that originate from the presence of isotopes itself. Hence, the high-temperature ALD is very effective in forming Al 2 O 3 films as a passivation and/or gate-insulation layer of high-temperature-operation diamond SC devices, and the knowledge of the aforementioned new isotope effect will be a basis for further enhancing ALD

Carbon allocation belowground in Pinus pinaster using stable carbon isotope pulse labeling technique

Science.gov (United States)

Dannoura, M.; Bosc, A.; Chipeaux, C.; Sartore, M.; Lambrot, C.; Trichet, P.; Bakker, M.; Loustau, D.; Epron, D.

2010-12-01

Carbon allocation belowground competes with aboveground growth and biomass production. In the other hand, it contributes to resource acquisition such as nutrient, water and carbon sequestration in soil. Thus, a better characterization of carbon flow from plant to soil and its residence time within each compartment is an important issue for understanding and modeling forest ecosystem carbon budget. 13C pulse labeling of whole crown was conducted at 4 seasons to study the fate of assimilated carbon by photosynthesis into the root on 12 year old Pinus pinaster planted in the INRA domain of Pierroton. Maritime pine is the most widely planted species in South-West Europe. Stem, root and soil CO2 effluxes and their isotope composition were measured continuously by tunable diode laser absorption spectroscopy with a trace gas analyzer (TGA 100A; Campbell Scientific) coupled to flow-through chambers. 13CO2 recovery and peak were observed in respiration of each compartment after labeling. It appeared sequentially from top of stem to bottom, and to coarse root. The maximum velocity of carbon transfer was calculated as the difference in time lag of recovery between two positions on the trunk or on the root. It ranged between 0.08-0.2 m h-1 in stem and between 0.04-0.12 m h-1 in coarse root. This velocity was higher in warmer season, and the difference between time lag of recovery and peak increased after first frost. Photosynthates arrived underground 1.5 to 5 days after labeling, at similar time in soil CO2 effluxes and coarse root respiration. 0.08-1.4 g of carbon was respired per tree during first 20 days following labeling. It presented 0.6 -10% of 13C used for labeling and it is strongly related to seasons. The isotope signal was detected in fine root organs and microbial biomass by periodical core sampling. The peak was observed 6 days after labeling in early summer while it was delayed more than 10 days in autumn and winter with less amount of carbon allocated

Special graphites; Graphites speciaux

Energy Technology Data Exchange (ETDEWEB)

Leveque, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [French] Ameliorer les proprietes du graphite nucleaire pour empilements et ouvrir de nouveaux domaines d'application au graphite constituent une part importante de l'effort entrepris en commun par le Commissariat a l'Energie Atomique (CEA) et la compagnie PECHINEY. Des procedes nouveaux de fabrication de carbones et graphites speciaux ont ete mis au point: graphite forge, pyrocarbone, graphite de haute densite, agglomeration de poudres de graphite par craquage de gaz naturel, graphites impermeables. Les proprietes physiques de ces produits ainsi que leur reaction avec differents gaz oxydants sont decrites. Les premiers resultats d'irradiation sont aussi donnes. (auteurs)

Chemical Ligation and Isotope Labeling to Locate Dynamic Effects during Catalysis by Dihydrofolate Reductase.

Science.gov (United States)

Luk, Louis Y P; Ruiz-Pernía, J Javier; Adesina, Aduragbemi S; Loveridge, E Joel; Tuñón, Iñaki; Moliner, Vincent; Allemann, Rudolf K

2015-07-27

Chemical ligation has been used to alter motions in specific regions of dihydrofolate reductase from E. coli and to investigate the effects of localized motional changes on enzyme catalysis. Two isotopic hybrids were prepared; one with the mobile N-terminal segment containing heavy isotopes ((2) H, (13) C, (15) N) and the remainder of the protein with natural isotopic abundance, and the other one with only the C-terminal segment isotopically labeled. Kinetic investigations indicated that isotopic substitution of the N-terminal segment affected only a physical step of catalysis, whereas the enzyme chemistry was affected by protein motions from the C-terminal segment. QM/MM studies support the idea that dynamic effects on catalysis mostly originate from the C-terminal segment. The use of isotope hybrids provides insights into the microscopic mechanism of dynamic coupling, which is difficult to obtain with other studies, and helps define the dynamic networks of intramolecular interactions central to enzyme catalysis. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Carbon isotope exchange between gaseous CO2 and thin solution films: Artificial cave experiments and a complete diffusion-reaction model

Science.gov (United States)

Hansen, Maximilian; Scholz, Denis; Froeschmann, Marie-Louise; Schöne, Bernd R.; Spötl, Christoph

2017-08-01

Speleothem stable carbon isotope (δ13C) records provide important paleoclimate and paleo-environmental information. However, the interpretation of these records in terms of past climate or environmental change remains challenging because of various processes affecting the δ13C signals. A process that has only been sparsely discussed so far is carbon isotope exchange between the gaseous CO2 of the cave atmosphere and the dissolved inorganic carbon (DIC) contained in the thin solution film on the speleothem, which may be particularly important for strongly ventilated caves. Here we present a novel, complete reaction diffusion model describing carbon isotope exchange between gaseous CO2 and the DIC in thin solution films. The model considers all parameters affecting carbon isotope exchange, such as diffusion into, out of and within the film, the chemical reactions occurring within the film as well as the dependence of diffusion and the reaction rates on isotopic mass and temperature. To verify the model, we conducted laboratory experiments under completely controlled, cave-analogue conditions at three different temperatures (10, 20, 30 °C). We exposed thin (≈0.1 mm) films of a NaHCO3 solution with four different concentrations (1, 2, 5 and 10 mmol/l, respectively) to a nitrogen atmosphere containing a specific amount of CO2 (1000 and 3000 ppmV). The experimentally observed temporal evolution of the pH and δ13C values of the DIC is in good agreement with the model predictions. The carbon isotope exchange times in our experiments range from ca. 200 to ca. 16,000 s and strongly depend on temperature, film thickness, atmospheric pCO2 and the concentration of DIC. For low pCO2 (between 500 and 1000 ppmV, as for strongly ventilated caves), our time constants are substantially lower than those derived in a previous study, suggesting a potentially stronger influence of carbon isotope exchange on speleothem δ13C values. However, this process should only have an

The application of high-resolution IR spectroscopy and isotope labeling for detailed investigation of TiO2/gas interface reactions

Czech Academy of Sciences Publication Activity Database

Civiš, Svatopluk; Ferus, Martin; Zukalová, Markéta; Kavan, Ladislav; Zelinger, Zdeněk

2013-01-01

Roč. 36, č. 1 (2013), s. 159-162 ISSN 0925-3467 R&D Projects: GA ČR GAP208/10/2302; GA ČR GA13-07724S Institutional support: RVO:61388955 Keywords : isotope exchange * titania * isotope labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.075, year: 2013

Validation of 13CO2 breath analysis as a measurement of demethylation of stable isotope labeled aminopyrine in man

International Nuclear Information System (INIS)

Schneider, J.F.; Schoeller, D.A.; Nemchausky, B.; Bayer, J.L.; Klein, P.

1978-01-01

Interval sampling of expired breath as a simple, non-invasive assessment of the effect of liver disease upon hepatic microsomal drug metabolism, has been demonstrated with [ 14 C] dimethylaminoantipyrine (aminopyrine). In order to eliminate radiation risk the authors have validated the use of aminopyrine labeled with the stable, non-radioactive isotope 13 C. Simultaneous oral administration of both [ 14 C]- and [ 13 C] aminopyrine to five adult subjects without liver disease as well as five patients with known liver disease, resulted in the excretion of label at nearly identical rates in both individual time collections (r=0.94) as well as cumulative excretion for three hours (r=0.97). An oral dose of 2-mg/kg of [ 13 C) aminopyrine resulted in rates of production of 13 CO 2 significantly greater than baseline variations in 13 CO 2 production in the fasting, resting subject. Measurements of a single peak value at one half hour correlated closely with the determination of cumulative appearance over three hours (r=0.96). A consistent reproducible increase in the peak production of 13 CO 2 was observed when five patients received phenobarbital. Stable isotope labeled aminopyrine may be used to detect the effects of disease and treatment upon hepatic N-demethylation activity in human subjects without incurring any risk from radiation. Furthermore, the availability of another isotopic carbon label should make possible the study of direct drug-drug interaction utilizing CO 2 analysis. (Auth.)

Selectively dispersed isotope labeling for protein structure determination by magic angle spinning NMR

Energy Technology Data Exchange (ETDEWEB)

Eddy, Matthew T. [Massachusetts Institute of Technology, Department of Chemistry (United States); Belenky, Marina [Brandeis University, Department of Chemistry (United States); Sivertsen, Astrid C. [Massachusetts Institute of Technology, Francis Bitter Magnet Laboratory (United States); Griffin, Robert G. [Massachusetts Institute of Technology, Department of Chemistry (United States); Herzfeld, Judith, E-mail: herzfeld@brandeis.edu [Brandeis University, Department of Chemistry (United States)

2013-10-15

The power of nuclear magnetic resonance spectroscopy derives from its site-specific access to chemical, structural and dynamic information. However, the corresponding multiplicity of interactions can be difficult to tease apart. Complimentary approaches involve spectral editing on the one hand and selective isotope substitution on the other. Here we present a new 'redox' approach to the latter: acetate is chosen as the sole carbon source for the extreme oxidation numbers of its two carbons. Consistent with conventional anabolic pathways for the amino acids, [1-{sup 13}C] acetate does not label {alpha} carbons, labels other aliphatic carbons and the aromatic carbons very selectively, and labels the carboxyl carbons heavily. The benefits of this labeling scheme are exemplified by magic angle spinning spectra of microcrystalline immunoglobulin binding protein G (GB1): the elimination of most J-couplings and one- and two-bond dipolar couplings provides narrow signals and long-range, intra- and inter-residue, recoupling essential for distance constraints. Inverse redox labeling, from [2-{sup 13}C] acetate, is also expected to be useful: although it retains one-bond couplings in the sidechains, the removal of CA-CO coupling in the backbone should improve the resolution of NCACX spectra.

PVA-based nanographene film by electrospinning

Directory of Open Access Journals (Sweden)

Pang Jing

2013-01-01

Full Text Available Two-dimensional polyvinyl alcohol based graphene films with the thickness of less than 20 nm were fabricated directly by using polyvinyl alcohol/graphite solution or polyvinyl alcohol/ash solution by electrospinning. It was found that ash particles are good candidate for substitution of graphite particles to fabricate nanographene films. The relationship between the thickness and width of the film is elucidated, and the periodic morphology of the film is explained.

Identification of miRNA targets with stable isotope labeling by amino acids in cell culture

DEFF Research Database (Denmark)

Vinther, Jeppe; Hedegaard, Mads Marquardt; Gardner, Paul Phillip

2006-01-01

miRNAs are small noncoding RNAs that regulate gene expression. We have used stable isotope labeling by amino acids in cell culture (SILAC) to investigate the effect of miRNA-1 on the HeLa cell proteome. Expression of 12 out of 504 investigated proteins was repressed by miRNA-1 transfection...

Modification degrees at specific sites on heparan sulphate: an approach to measure chemical modifications on biological molecules with stable isotope labelling

Science.gov (United States)

Wu, Zhengliang L.; Lech, Miroslaw

2005-01-01

Chemical modification of biological molecules is a general mechanism for cellular regulation. A quantitative approach has been developed to measure the extent of modification on HS (heparan sulphates). Sulphation on HS by sulphotransferases leads to variable sulphation levels, which allows cells to tune their affinities to various extracellular proteins, including growth factors. With stable isotope labelling and HPLC-coupled MS, modification degrees at various O-sulphation sites could be determined. A bovine kidney HS sample was first saturated in vitro with 34S by an OST (O-sulphotransferase), then digested with nitrous acid and analysed with HPLC-coupled MS. The 34S-labelled oligosaccharides were identified based on their unique isotope clusters. The modification degrees at the sulphotransferase recognition sites were obtained by calculating the intensities of isotopic peaks in the isotope clusters. The modification degrees at 3-OST-1 and 6-OST-1 sites were examined in detail. This approach can also be used to study other types of chemical modifications on biological molecules. PMID:15743272

Development of Nanoscale Graphitic Devices and The Transport Characterization

International Nuclear Information System (INIS)

Gunasekaran, Venugopal

2011-02-01

This dissertation describes the development of graphitic based nanoscale devices with its fabrication and transport characterization results. It covers graphite nano-scale stacked-junctions fabricated using focused ion beam (FIB) 3-D etching technique, a single layer graphite layer (graphene) preparation and its electrical transport characterization results and the synthesis and investigation of electrical transport behavior of graphene oxide based thin film devices. The first chapter describes the basic information about the carbon family in detail in which the electronic properties and structure of graphite, graphene and graphene oxide are discussed. In addition, the necessity of developing nanoscale graphitic devices is given. The second chapter explains the experimental techniques used in this research for fabricating nanoscale devices which includes focused ion beam 3-D fabrication procedures, mechanical exfoliation technique and photolithographic methods. In third chapter, we have reported the results on temperature dependence of graphite planar-type structures fabricated along ab-plane. In the fourth and fifth chapters, the fabrication and electrical transport characteristics of large in-plane area graphite planar-type structures (fabricated along ab-plane and c-axis) were discussed and their transport anisotropy properties were investigated briefly. In the sixth chapter, we focused the fabrication of the submicron sized graphite stacked junctions and their electrical transport characterization studies. In which, FIB was used to fabricated the submicron junctions with various in-plane area (with same stack height) are and their transport characteristics were compared. The seventh chapter reports investigation of electrical transport results of nanoscale graphite stacked-junctions in which the temperature dependent transport (R-T) studies, current-voltage measurements for the various in-plane areas and for various stack height samples were analyzed. The

Brazing graphite to graphite

International Nuclear Information System (INIS)

Peterson, G.R.

1976-01-01

Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of graphite

Preparation of H3-labelled methyl ethers of saturated fatty acids by heterogeneous catalytic isotope exchange in solution with gaseous tritium

International Nuclear Information System (INIS)

Shevchenko, V.P.; Myasoedov, N.F.

1980-01-01

A simple method of preparing 3 H-labelled methyl ethers of saturated fatty acids in the dioxane solution using the method of isotopic heterogenous catalytic exchange with gaseous tritium, is suggested. 3 H-labelled natural fatty acids (C 12 -C 18 ) are prepared by alkaline hydrolysis [ru

Nanostructuration of self-assembled poly(styrene-b-isoprene-b-styrene) block copolymer thin films in a highly oriented pyrolytic graphite substrate

Energy Technology Data Exchange (ETDEWEB)

Zalakain, Inaki; Ramos, Jose Angel; Fernandez, Raquel; Etxeberria, Haritz; Mondragon, Inaki, E-mail: inaki.mondragon@ehu.e

2011-01-03

Highly oriented pyrolitic graphite (HOPG) is a useful substrate to visualize epitaxial formation due to its crystallographic structure. The morphology of a poly(styrene-b-isoprene-b-styrene) block copolymer thin film on a HOPG substrate was investigated by atomic force microscopy. Block copolymer domains generated a morphology with triangular regularity. This arrangement was induced by the HOPG substrate structure due to van der Waals attraction between the HOPG {pi}-conjugated system and aromatic ring of polystyrene domains. However, increasing the film thickness, the substrate effect on the surface morphology decreased. As a consequence, film surfaces showed the coexistence of different structures such as highly aligned cylinders and perforated lamellae. When film thickness exceeded a threshold value, the substrate did not have effect in the surface arrangements and the surface showed a similar morphology to that existing in bulk.

Friction and wear of carbon-graphite materials for high-energy brakes

Science.gov (United States)

Bill, R. C.

1978-01-01

Caliper type brake simulation experiments were conducted on seven different carbon graphite materials formulations against a steel disk material and against a carbon graphite disk material. The effects of binder level, boron carbide (B4C) additions, SiC additions, graphite fiber additions, and graphite cloth reinforcement on friction and wear behavior were investigated. Reductions in binder level, additions of B4C, and additions of SiC each resulted in increased wear. The wear rate was not affected by the addition of graphite fibers. Transition to severe wear and high friction was observed in the case of graphite-cloth-reinforced carbon sliding against a disk of similar composition. The transition was related to the disruption of a continuous graphite shear film that must form on the sliding surfaces if low wear is to occur.

Development of high-performance chemical isotope labeling LC-MS for profiling the human fecal metabolome.

Science.gov (United States)

Xu, Wei; Chen, Deying; Wang, Nan; Zhang, Ting; Zhou, Ruokun; Huan, Tao; Lu, Yingfeng; Su, Xiaoling; Xie, Qing; Li, Liang; Li, Lanjuan

2015-01-20

Human fecal samples contain endogenous human metabolites, gut microbiota metabolites, and other compounds. Profiling the fecal metabolome can produce metabolic information that may be used not only for disease biomarker discovery, but also for providing an insight about the relationship of the gut microbiome and human health. In this work, we report a chemical isotope labeling liquid chromatography-mass spectrometry (LC-MS) method for comprehensive and quantitative analysis of the amine- and phenol-containing metabolites in fecal samples. Differential (13)C2/(12)C2-dansyl labeling of the amines and phenols was used to improve LC separation efficiency and MS detection sensitivity. Water, methanol, and acetonitrile were examined as an extraction solvent, and a sequential water-acetonitrile extraction method was found to be optimal. A step-gradient LC-UV setup and a fast LC-MS method were evaluated for measuring the total concentration of dansyl labeled metabolites that could be used for normalizing the sample amounts of individual samples for quantitative metabolomics. Knowing the total concentration was also useful for optimizing the sample injection amount into LC-MS to maximize the number of metabolites detectable while avoiding sample overloading. For the first time, dansylation isotope labeling LC-MS was performed in a simple time-of-flight mass spectrometer, instead of high-end equipment, demonstrating the feasibility of using a low-cost instrument for chemical isotope labeling metabolomics. The developed method was applied for profiling the amine/phenol submetabolome of fecal samples collected from three families. An average of 1785 peak pairs or putative metabolites were found from a 30 min LC-MS run. From 243 LC-MS runs of all the fecal samples, a total of 6200 peak pairs were detected. Among them, 67 could be positively identified based on the mass and retention time match to a dansyl standard library, while 581 and 3197 peak pairs could be putatively

Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

Science.gov (United States)

Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

2015-09-01

We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

An economic approach to efficient isotope labeling in insect cells using homemade 15N-, 13C- and 2H-labeled yeast extracts

International Nuclear Information System (INIS)

Opitz, Christian; Isogai, Shin; Grzesiek, Stephan

2015-01-01

Heterologous expression of proteins in insect cells is frequently used for crystallographic structural studies due to the high yields even for challenging proteins requiring the eukaryotic protein processing capabilities of the host. However for NMR studies, the need for isotope labeling poses extreme challenges in eukaryotic hosts. Here, we describe a robust method to achieve uniform protein 15 N and 13 C labeling of up to 90 % in baculovirus-infected insect cells. The approach is based on the production of labeled yeast extract, which is subsequently supplemented to insect cell growth media. The method also allows deuteration at levels of >60 % without decrease in expression yield. The economic implementation of the labeling procedures into a standard structural biology laboratory environment is described in a step-by-step protocol. Applications are demonstrated for a variety of NMR experiments using the Abelson kinase domain, GFP, and the beta-1 adrenergic receptor as examples. Deuterated expression of the latter provides spectra of very high quality of a eukaryotic G-protein coupled receptor

Quantitative amino acid profiling and stable isotopically labeled amino acid tracer enrichment used for in vivo human systemic and tissue kinetics measurements

DEFF Research Database (Denmark)

Bornø, Andreas; van Hall, Gerrit

2014-01-01

An important area within clinical functional metabolomics is in vivo amino acid metabolism and protein turnover measurements for which accurate amino acid concentrations and stable isotopically labeled amino acid enrichments are mandatory not the least when tissue metabolomics is determined....... The present study describes a new sensitive liquid chromatography tandem mass-spectrometry method quantifying 20 amino acids and their tracer(s) ([ring-(13)C6]/D5Phenylalanine) in human plasma and skeletal muscle specimens. Before analysis amino acids were extracted and purified via deprotonization....../ion exchange, derivatized using a phenylisothiocyanate reagent and each amino acid was quantitated with its own stable isotopically labeled internal standard (uniformly labeled-(13)C/(15)N). The method was validated according to general recommendations for chromatographic analytical methods. The calibration...

In-situ electric resistance measurements and annealing effects of graphite exposed to swift heavy ions

International Nuclear Information System (INIS)

Fernandes, Sandrina; Pellemoine, Frederique; Tomut, Marilena; Avilov, Mikhail; Bender, Markus; Boulesteix, Marine; Krause, Markus; Mittig, Wolfgang; Schein, Mike; Severin, Daniel; Trautmann, Christina

2013-01-01

To study the suitability of using graphite as material for high-power targets for rare isotope production at the future Facility for Rare Isotope Beams (FRIB) in the USA and at the Facility for Antiproton and Ion Research (FAIR) in Germany, thin foils of polycrystalline graphite were exposed to 8.6-MeV/u Au ions reaching a maximum fluence of 1 × 10 15 ions/cm 2 . Foil irradiation temperatures of up to 1800 °C were obtained by ohmic heating. In-situ monitoring of the electrical resistance of the graphite foils during and after irradiation provided information on beam-induced radiation damage. The rate of electrical resistance increase as a function of fluence was found to decrease with increasing irradiation temperature, indicating a more efficient annealing of the irradiation-produced defects. This is corroborated by the observation that graphite foils irradiated at temperatures below about 800 °C showed cracks and pronounced deformations, which did not appear on the samples irradiated at higher temperatures

Modification of PMMA/graphite nanocomposites through ion beam technique

Science.gov (United States)

Singhal, Prachi; Rattan, Sunita; Avasthi, Devesh Kumar; Tripathi, Ambuj

2013-08-01

Swift heavy ion (SHI) irradiation is a special technique for inducing physical and chemical modifications in bulk materials. In the present work, the SHI hs been used to prepare nanocomposites with homogeneously dispersed nanoparticles. The nanographite was synthesized from graphite using the intercalation-exfoliation method. PMMA Poly(methyl methacrylate)/graphite nanocomposites have been synthesized by in situ polymerization. The prepared PMMA/graphite nanocomposite films were irradiated with SHI irradiation (Ni ion beam, 80 MeV and C ion beam, 50 MeV) at a fluence of 1×1010 to 3×1012 ions/cm2. The nanocomposite films were characterized by scanning electron microscope (SEM) and were evaluated for their electrical and sensor properties. After irradiation, significant changes in surface morphology of nanocomposites were observed as evident from the SEM images, which show the presence of well-distributed nanographite platelets. The irradiated nanocomposites exhibit better electrical and sensor properties for the detection of nitroaromatics with marked improvement in sensitivity as compared with unirradiated nanocomposites.

Improved segmental isotope labeling of proteins and application to a larger protein

International Nuclear Information System (INIS)

Otomo, Takanori; Teruya, Kenta; Uegaki, Koichi; Yamazaki, Toshio; Kyogoku, Yoshimasa

1999-01-01

A new isotope labeling technique for peptide segments in a protein sample was recently established using the protein splicing element intein [Yamazaki et al. (1998) J. Am. Chem. Soc., 120, 5591-5592]. This method makes it possible to observe signals of a selected amino (N-) or carboxyl (C-) terminal region along a peptide chain. However, there is a problem with the yield of the segmentally labeled protein. In this paper, we report an increase in the yield of the protein that enables the production of sufficient amounts of segmentally 13 C/ 15 N-labeled protein samples. This was achieved by improvement of the expression level of the N-terminal fragment in cells and the efficiency of refolding into the active splicing conformation. The N-terminal fragment was expressed as a fused protein with the cellulose binding domain at its N-terminus, which was expressed as an insoluble peptide in cells and the expression level was increased. Incubation with 2.5 M urea and 50% glycerol increased the efficiency of the refolding greatly, thereby raising the final yields of the ligated proteins. The feasibility of application of the method to a high-molecular-weight protein was demonstrated by the results for a maltose binding protein consisting of 370 amino acids. All four examined joints in the maltose binding protein were successfully ligated to produce segmentally labeled protein samples

The synthesis of tritium, carbon-14 and stable isotope labelled selective estrogen receptor degraders.

Science.gov (United States)

Bragg, Ryan A; Bushby, Nick; Ericsson, Cecilia; Kingston, Lee P; Ji, Hailong; Elmore, Charles S

2016-09-01

As part of a Medicinal Chemistry program aimed at developing an orally bioavailable selective estrogen receptor degrader, a number of tritium, carbon-14, and stable isotope labelled (E)-3-[4-(2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl]prop-2-enoic acids were required. This paper discusses 5 synthetic approaches to this compound class. Copyright © 2016 John Wiley & Sons, Ltd.

Mechanical and tribological properties of acrylonitrile–butadiene rubber filled with graphite and carbon black

International Nuclear Information System (INIS)

Wang, Lei Lei; Zhang, Li Qun; Tian, Ming

2012-01-01

Highlights: ► Graphite/carbon black/rubber micro- and nano-composites were prepared. ► Nanocomposites showed better mechanical properties and wear resistance. ► The effect of load and sliding speed on friction and wear is significant. ► Graphite lubricant film can reduce friction coefficient and wear rate. -- Abstract: In this work, acrylonitrile–butadiene rubber (NBR)/expanded graphite (EG)/carbon black (CB) micro- and nanocomposites were prepared by two different methods, and the resulting mechanical and tribological properties were compared with those of NBR/CB composites. Meanwhile, the effects of graphite dispersion and loading content, as well as the applied load and sliding velocity on the tribological behavior of the above composites under dry friction condition were also evaluated. The worn surfaces were analyzed by scanning electron microscopy (SEM) to disclose wear mechanism. As expected, the better the dispersion of graphite, the more remarkable enhancement on tensile and dynamic mechanical properties, and the greater reduction in the coefficient of friction (COF) and specific wear rate (W s ). It was found that a small amount of EG could effectively decrease COF and W s of NBR/CB composites because of the formation of graphite lubricant films. The COF and W s of NBR/CB/EG composites show a decreasing trend with a rise in applied load and sliding velocity. NBR/CB/EG nanocomposite always shows a stable wearing process with relatively low COF and W s . It is thought that well-dispersed graphite nano-sheets were beneficial to the formation of a fine and durable lubricant film.

Reactions of modulated molecular beams with pyrolytic graphite IV. Water vapor

International Nuclear Information System (INIS)

Olander, D.R.; Acharya, T.R.; Ullman, A.Z.

1977-01-01

The reaction of water vapor with the prism plane face of anneal pyrolytic graphite was investigated by modulated molecular beam--mass spectrometry methods. The equivalent water vapor pressure of the beam was approx.2 x 10 -5 Torr and the graphite temperature was varied from 300 to 2500 0 K. The mechanism was deduced from three types of experiments: isotope exchange utilizing modulated H 2 O and steady D 2 O beams; measurements of the phase difference between H 2 O and neon reflected from the surface from a mixed primary beam of these species; and reaction of a modulated H 2 O beam to produce CO and H 2 . Based upon the isotope exchange experiments chemisorption of water on graphite was found to be dissociative and reversible. Incident water molecules chemisorbed with a sticking probability of 0.15 +- 0.02 to form the complexes C--OH and C--H. Recombination of the surface complexes reverses the adsorption step and is responsible for the isotope exchange properties of the graphite surface. This process is unactivated. Reaction to produce CO and H 2 also results from collisions of the primary surface complexes, but this step has an activation energy of 170 kJ/mole. This reaction yields bound complexes tentatively identified as C--O and H--C--H, which then decompose to produce the stable reaction products. All of the above steps exhibit characteristic times on the order of milliseconds, and are therefore detectable by the modulated beam method. All surface intermediates are strongly affected by solution and diffusion in the bulk of the solid

ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

Energy Technology Data Exchange (ETDEWEB)

BULLOCK,R.M.; BENDER,B.R.

2000-12-01

The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

Studies of phosphorus-containing fertilizer uptake in soils by 32P isotope labelling

International Nuclear Information System (INIS)

Fueleky, Gyoergy; Osztoics, Andrasne; Papne Kranitz, Erzsebet

1983-01-01

Breeding experiments were carried out with rye-grass (Lolium perenne L.) on two soil types to determine the plant uptake of phosphorus from naturally occuring element and from that added to the soil by superphosphate fertilizers. 32 P isotope labelling and radiometric measuring method were applied. In addition to the determination of phosphorus uptake, the phosphorus contents of the soil from its natural stock and from the fertilizer for both soil types can be determined by this method. (A.L.)

The Effect of Thermal Annealing on the Optical Properties of a-SiC:H Films Produced by DC Sputtering Methods: I. Graphite Target Case.

Directory of Open Access Journals (Sweden)

Lusitra Munisa

2003-04-01

Full Text Available A study of the annealing effect on optical properties and disorder of hydrogenated amorphous silicon carbon (a-SiC:H films was undertaken. The films were prepared by sputtering technique using graphite target and silicon wafer in argon and hydrogen gas mixture, and then characterized by uv-vis (ultra violet-visible spectroscopy before and after annealing. Index of refraction n and absorption coefficient α of films have been determined from measurements of transmittance. The optical gap show small variation with annealing temperature, increasing with increasing annealing temperature up to 500 °C. An increase of annealing temperature leads to reduced film density and the amorphous network disorder. The experimental results are discussed in terms of deposition condition and compared to other experimental results.

Measurements of the thermophysical properties of graphite composites for a neutron target converter

Energy Technology Data Exchange (ETDEWEB)

Zhmurikov, E.I. [Budker Institute of Nuclear Physics, 690090 Novosibirsk, SB RAS (Russian Federation); Savchenko, I.V.; Stankus, S.V.; Yatsuk, O.S. [Kutateladze Institute of Thermal Physics, 690090 Novosibirsk, SB RAS (Russian Federation); Tecchio, L.B., E-mail: tecchio@lnl.infn.it [Laboratori Nazionali di Legnaro-Istituto Nazionale di Fisica Nucleare, Legnaro (Italy)

2012-05-11

The thermo-physical characteristics of both nuclear, industrial graphite, such as MPG-6 from NIIGRAFIT or SGL composite from SGL Carbon Group, and the first synthesized graphite composite based on a carbon {sup 13}S isotope have been measured from room temperature to 1675 K by laser flash method on an LFA-427 setup from Netzsch (Germany). The results obtained are compared to the previous data of X-Ray analysis and high-resolution electron microscopy and can be used in thermal calculations of the design of a neutron converter graphite target.

Measurements of the thermophysical properties of graphite composites for a neutron target converter

International Nuclear Information System (INIS)

Zhmurikov, E.I.; Savchenko, I.V.; Stankus, S.V.; Yatsuk, O.S.; Tecchio, L.B.

2012-01-01

The thermo-physical characteristics of both nuclear, industrial graphite, such as MPG-6 from NIIGRAFIT or SGL composite from SGL Carbon Group, and the first synthesized graphite composite based on a carbon 13 S isotope have been measured from room temperature to 1675 K by laser flash method on an LFA-427 setup from Netzsch (Germany). The results obtained are compared to the previous data of X-Ray analysis and high-resolution electron microscopy and can be used in thermal calculations of the design of a neutron converter graphite target.

Effect of covalently bonded polysiloxane multilayers on the electrochemical behavior of graphite electrode in lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Pan, Qinmin; Jiang, Yinghua [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

2008-03-15

Polysiloxane multilayers were covalently bonded to the surface of natural graphite particles via diazonium chemistry and silylation reaction. The as-prepared graphite exhibited excellent discharge-charge behavior as negative electrode materials in lithium ion batteries. The improvement in the electrochemical performance of the graphite electrodes was attributed to the formation of a stable and flexible passive film on their surfaces. It was also revealed that the chemical compositions of the multilayers exerted influence on the electrochemical behavior of the graphite electrodes. The result of this study presents a new strategy to the formation of elastic and strong passive film on the graphite electrode via molecular design. Owing to the diversity of polysilxoane multilayers, this method also enables researchers to control the surface chemistries of carbonaceous materials with flexibility. (author)

Actinides in irradiated graphite of RBMK-1500 reactor

Energy Technology Data Exchange (ETDEWEB)

Plukienė, R., E-mail: rita@ar.fi.lt; Plukis, A.; Barkauskas, V.; Gudelis, A.; Gvozdaitė, R.; Duškesas, G.; Remeikis, V.

2014-10-01

Highlights: • Activation of actinides in the graphite of the RBMK-1500 reactor was analyzed. • Numerical modeling using SCALE 6.1 and MCNPX was used for actinide calculation. • Measurements of the irradiated graphite sample were used for model validation. • Results are important for further decommissioning process of the RBMK type reactors. - Abstract: The activation of graphite in the nuclear power plants is the problem of high importance related with later graphite reprocessing or disposal. The activation of actinide impurities in graphite due to their toxicity determines a particular long term risk to waste management. In this work the activation of actinides in the graphite constructions of the RBMK-1500 reactor is determined by nuclear spectrometry measurements of the irradiated graphite sample from the Ignalina NPP Unit I and by means of numerical modeling using two independent codes SCALE 6.1 (using TRITON-VI sequence) and MCNPX (v2.7 with CINDER). Both models take into account the 3D RBMK-1500 reactor core fragment with explicit graphite construction including a stack and a sleeve but with a different simplification level concerning surrounding graphite and construction of control roads. The verification of the model has been performed by comparing calculated and measured isotope ratios of actinides. Also good prediction capabilities of the actinide activation in the irradiated graphite have been found for both calculation approaches. The initial U impurity concentration in the graphite model has been adjusted taking into account the experimental results. The specific activities of actinides in the irradiated RBMK-1500 graphite constructions have been obtained and differences between numerical simulation results, different structural parts (sleeve and stack) as well as comparison with previous results (Ancius et al., 2005) have been discussed. The obtained results are important for further decommissioning process of the Ignalina NPP and other RBMK

In-situ electric resistance measurements and annealing effects of graphite exposed to swift heavy ions

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Sandrina [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI (United States); Pellemoine, Frederique, E-mail: pellemoi@frib.msu.edu [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI (United States); Tomut, Marilena [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); National Institute for Materials Physics (NIMP), Bucharest (Romania); Avilov, Mikhail [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI (United States); Bender, Markus [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Boulesteix, Marine [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI (United States); Krause, Markus [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Technische Universität, Darmstadt (Germany); Mittig, Wolfgang [National Superconducting Cyclotron Lab (NSCL), Michigan State University, East Lansing, MI (United States); Schein, Mike [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI (United States); Severin, Daniel [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Trautmann, Christina [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Technische Universität, Darmstadt (Germany)

2013-11-01

To study the suitability of using graphite as material for high-power targets for rare isotope production at the future Facility for Rare Isotope Beams (FRIB) in the USA and at the Facility for Antiproton and Ion Research (FAIR) in Germany, thin foils of polycrystalline graphite were exposed to 8.6-MeV/u Au ions reaching a maximum fluence of 1 × 10{sup 15} ions/cm{sup 2}. Foil irradiation temperatures of up to 1800 °C were obtained by ohmic heating. In-situ monitoring of the electrical resistance of the graphite foils during and after irradiation provided information on beam-induced radiation damage. The rate of electrical resistance increase as a function of fluence was found to decrease with increasing irradiation temperature, indicating a more efficient annealing of the irradiation-produced defects. This is corroborated by the observation that graphite foils irradiated at temperatures below about 800 °C showed cracks and pronounced deformations, which did not appear on the samples irradiated at higher temperatures.

Formation of Hydroxymethyl DNA Adducts in Rats Orally Exposed to Stable Isotope Labeled Methanol

Science.gov (United States)

Lu, Kun; Gul, Husamettin; Upton, Patricia B.; Moeller, Benjamin C.; Swenberg, James A.

2012-01-01

Methanol is a large volume industrial chemical and widely used solvent and fuel additive. Methanol’s well known toxicity and use in a wide spectrum of applications has raised long-standing environmental issues over its safety, including its carcinogenicity. Methanol has not been listed as a carcinogen by any regulatory agency; however, there are debates about its carcinogenic potential. Formaldehyde, a metabolite of methanol, has been proposed to be responsible for the carcinogenesis of methanol. Formaldehyde is a known carcinogen and actively targets DNA and protein, causing diverse DNA and protein damage. However, formaldehyde-induced DNA adducts arising from the metabolism of methanol have not been reported previously, largely due to the absence of suitable DNA biomarkers and the inability to differentiate what was due to methanol compared with the substantial background of endogenous formaldehyde. Recently, we developed a unique approach combining highly sensitive liquid chromatography-mass spectrometry methods and exposure to stable isotope labeled chemicals to simultaneously quantify formaldehyde-specific endogenous and exogenous DNA adducts. In this study, rats were exposed daily to 500 or 2000 mg/kg [13CD4]-methanol by gavage for 5 days. Our data demonstrate that labeled formaldehyde arising from [13CD4]-methanol induced hydroxymethyl DNA adducts in multiple tissues in a dose-dependent manner. The results also demonstrated that the number of exogenous DNA adducts was lower than the number of endogenous hydroxymethyl DNA adducts in all tissues of rats administered 500 mg/kg per day for 5 days, a lethal dose to humans, even after incorporating an average factor of 4 for reduced metabolism due to isotope effects of deuterium-labeled methanol into account. PMID:22157354

Isotope labelling study of CO oxidation-assisted epoxidation of propene. Implications for oxygen activation on Au catalysts.

Science.gov (United States)

Jiang, Jian; Oxford, Sean M; Fu, Baosong; Kung, Mayfair C; Kung, Harold H; Ma, Jiantai

2010-06-07

(18)O isotope labelling studies of the CO oxidation-assisted epoxidation of propene, catalyzed by a mixture of Au/TiO(2) and TS-1, using a methanol-H(2)O solvent showed the O in the epoxide was exclusively from O(2) and not H(2)O or methanol.

Round robin analyses of hydrogen isotope thin films standards

Energy Technology Data Exchange (ETDEWEB)

Banks, J.C. E-mail: jcbanks@sandia.gov; Browning, J.F.; Wampler, W.R.; Doyle, B.L.; LaDuca, C.A.; Tesmer, J.R.; Wetteland, C.J.; Wang, Y.Q

2004-06-01

Hydrogen isotope thin film standards have been manufactured at Sandia National Laboratories for use by the materials characterization community. Several considerations were taken into account during the manufacture of the ErHD standards, with accuracy and stability being the most important. The standards were fabricated by e-beam deposition of Er onto a Mo substrate and the film stoichiometrically loaded with hydrogen and deuterium. To determine the loading accuracy of the standards two random samples were measured by thermal desorption mass spectrometry and atomic absorption spectrometry techniques with a stated combined accuracy of {approx}1.6% (1{sigma}). All the standards were then measured by high energy RBS/ERD and RBS/NRA with the accuracy of the techniques {approx}5% (1{sigma}). The standards were then distributed to the IBA materials characterization community for analysis. This paper will discuss the suitability of the standards for use by the IBA community and compare measurement results to highlight the accuracy of the techniques used.

Synthesis of {sup 15}N isotope labeled alanine; Sintese da alanina enriquecida com {sup 15}N

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Claudineia R. de; Bendassolli, Jose Albertino; Sant' Ana, Carlos Roberto; Tagliassachi, Romulo Barbieri; Maximo, Everaldo; Prestes, Clelber Vieira [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Dept. de Isotopos Estaveis]. E-mail: crolivei@cena.usp.br

2005-07-01

The application of light chemical elements and their stable isotopes in biological studies have been increased over the last years. The use of {sup 15}N labeled amino acids is an important tool for elucidation of peptides structures. This paper describe a method for the synthesis of {sup 15}N isotope labeled alanine at lower costs than international ones, as well as the details of the recovery system of the nitrogen residues. In the present work an amination of {alpha}-haloacids, with the bromopropionic carboxylic acid and labeled aqua ammonia ({sup 15}NH{sub 3} aq) was carried out. In order to avoid eventually losses of {sup 15}NH{sub 3}, special cares were adopted, since the production cost is high. Although the acquisition cost of the {sup 13}N (radioactive) labeled compounds is lower, the obtained stable tracer will allow the accomplishment of important studies of the nitrogen cycling in living things, less occupational and environment hazards, and the time limitation problems in field studies. The tests took place in triplicates with NH{sub 3} (aq) being employed. With the establishment of the system for {sup 15}NH{sub 3} recovery, an average of 94 % of the ammonia employed in the synthesis process was recovered. The purity of the amino acid was state determined by TLC (Thin Layer Chromatography) and HPLC (High-Performance Liquid Chromatography) with a fluorescence detector. The Rf and the retention time of the synthesized sample were similar the sigma standard. Finally, regarding the established conditions, it was possible to obtain the alanine with a production cost about 40 % lower than the international price. (author)

Decontamination of nuclear graphite by thermal processing; Dekontamination von Nukleargraphit durch thermische Behandlung

Energy Technology Data Exchange (ETDEWEB)

Florjan, Monika W.

2010-04-15

The main problem in view of the direct disposal of the nuclear graphite is its large volume. This waste contains long-lived and short-lived radionuclides which determine the waste strategy. The irradiated graphite possess high amount of the {sup 14}C isotope. The main object of the present work was the selective separation of {sup 14}C isotope from the isotope {sup 12}C by thermal treatment (pyrolysis, partial oxidation). A successful separation could reduce the radiotoxicity and offer a different disposal strategy. Three different graphite types were investigated. The samples originate from the reflector and from the flaking of spherical fuel elements of the high-temperature reactor (AVR) Juelich. The samples from the thermal column of the research reactor (Merlin, Juelich) were also investigated. The maximum tritium releases were obtained both in inert gas atmosphere (N{sub 2}) and under water vapour-oxidizing conditions at 1280 C and 900 C. Furthermore it could be shown that 28% of {sup 14}C could be released under inert gas conditions at a 1280 C. By additive of oxidizing agent such as water vapour and oxygen the {sup 14}C release could be increased. Under water vapour-oxidizing conditions at a temperature of 1280 C up to 93% of the {sup 14}C was separated from the graphite. The matrix corrosion of 5.4% was obtained. The selective separation of the {sup 14}C is possible, because a substantial part of the radiocarbon is bound near the grain boundary surfaces. (orig.)

Isotope analysis of diamond-surface passivation effect of high-temperature H{sub 2}O-grown atomic layer deposition-Al{sub 2}O{sub 3} films

Energy Technology Data Exchange (ETDEWEB)

Hiraiwa, Atsushi, E-mail: hiraiwa@aoni.waseda.jp, E-mail: qs4a-hriw@asahi-net.or.jp [Institute for Nanoscience and Nanotechnology, Waseda University, 513 Waseda-tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Saito, Tatsuya; Matsumura, Daisuke; Kawarada, Hiroshi, E-mail: kawarada@waseda.jp [Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan)

2015-06-07

The Al{sub 2}O{sub 3} film formed using an atomic layer deposition (ALD) method with trimethylaluminum as Al precursor and H{sub 2}O as oxidant at a high temperature (450 °C) effectively passivates the p-type surface conduction (SC) layer specific to a hydrogen-terminated diamond surface, leading to a successful operation of diamond SC field-effect transistors at 400 °C. In order to investigate this excellent passivation effect, we carried out an isotope analysis using D{sub 2}O instead of H{sub 2}O in the ALD and found that the Al{sub 2}O{sub 3} film formed at a conventional temperature (100 °C) incorporates 50 times more CH{sub 3} groups than the high-temperature film. This CH{sub 3} is supposed to dissociate from the film when heated afterwards at a higher temperature (550 °C) and causes peeling patterns on the H-terminated surface. The high-temperature film is free from this problem and has the largest mass density and dielectric constant among those investigated in this study. The isotope analysis also unveiled a relatively active H-exchange reaction between the diamond H-termination and H{sub 2}O oxidant during the high-temperature ALD, the SC still being kept intact. This dynamic and yet steady H termination is realized by the suppressed oxidation due to the endothermic reaction with H{sub 2}O. Additionally, we not only observed the kinetic isotope effect in the form of reduced growth rate of D{sub 2}O-oxidant ALD but found that the mass density and dielectric constant of D{sub 2}O-grown Al{sub 2}O{sub 3} films are smaller than those of H{sub 2}O-grown films. This is a new type of isotope effect, which is not caused by the presence of isotopes in the films unlike the traditional isotope effects that originate from the presence of isotopes itself. Hence, the high-temperature ALD is very effective in forming Al{sub 2}O{sub 3} films as a passivation and/or gate-insulation layer of high-temperature-operation diamond SC devices, and the knowledge of

Recycling of an amino acid label with prolonged isotope infusion: Implications for kinetic studies

International Nuclear Information System (INIS)

Schwenk, W.F.; Tsalikian, E.; Beaufrere, B.; Haymond, M.W.

1985-01-01

To investigate whether recycling of a labeled amino acid would occur after 24 h of infusion, two groups of normal volunteers were infused with [ 3 H]leucine and alpha-[ 14 C]-ketoisocaproate for 4 h and [ 2 H 3 ]leucine for either 4 or 24 h (groups I and II, respectively). Entry of [ 2 H 3 ]leucine at steady state into the plasma space was indistinguishable from its infusion rate for group I but 30% higher (P less than 0.001) than this rate for group II, demonstrating significant recycling of label. After discontinuation of the infusions, isotope disappearance from the plasma space was followed for 2 h. The 3 H and 14 C decay data for both groups suggest that plasma leucine and alpha- ketoisocaproate are derived from a single intracellular pool in the postabsorptive state. In group I, the 3 H and 2 H labels decayed identically; whereas, in group II, the decay of [ 2 H 3 ]-leucine and alpha- [ 2 H 3 ]ketoisocaproate was slower (P less than 0.01) than the decay of [ 3 H]leucine and alpha-[ 3 H]ketoisocaproate, confirming re-entry of label after a 24-h infusion. Therefore kinetic values calculated from models assuming no recycling of labeled amino acids are most likely not quantitative and must be interpreted with care when flux does not change or decreases

Studies on low-voltage x-ray radiography for graphite materials

International Nuclear Information System (INIS)

Muraoka, Susumu; Itami, Hiroharu

1978-09-01

Low-voltage radiography has been studied to provide optimum technique for graphite less than 50 mm thick. First we determined the exposure conditions under which the most appropriate photographic density can be obtained. By parametric studies, an exposure chart was prepared. Then we studied how the environment of photographing affected the film density. Thirdly, by use of graphite materials with artificial flaws, Image Quality Indicator (I.Q.I.) sensitivity was determined. Detectability of a crack depended on an incidence angle of X-rays onto a crack. Finally, we photographed graphites having natural flaws and gained a useful information. (author)

Deposition of thin films by retardation of an isotope separator beam

International Nuclear Information System (INIS)

Colligon, J.S.; Grant, W.A.; Williams, J.S.; Lawson, R.P.W.

1976-01-01

An ion optical lens system capable of retarding and focusing a mass-analysed ion beam, produced in the University of Salford isotope separator, from an energy of 20 keV to 50-60 eV is described. Using this system it is technically feasible to deposit spectroscopically pure ions of all species onto a substrate to produce thin film for devices and junctions. Preliminary investigations of the technique have been carried out using lead and copper ions which were deposited onto silicon single-crystal substrates. These ions were selected because their high mass relative to silicon allowed analyses of the deposited films by low-angle Rutherford backscattering of 2 MeV He ions; the single-crystal silicon substrate enabled the extent of damage due to unretarded neutral particles to be estimated from channelling data. Results for lead films showed that films less than 150 A in thickness were discontinuous and scanning electron microscopy confirmed their 'island' structure. For thicker deposits, of order 600 A, the films were continuous. Results are also presented for copper-lead sandwich layers produced by successive depositions. Channelling experiments indicated that the neutral component was less than 5% of the total ion-beam intensity. Investigations of the spatial distribution of the lead films indicated a non-uniformity which, it is suggested, arises from a fault in the retardation lens design. (author)

iMS2Flux – a high–throughput processing tool for stable isotope labeled mass spectrometric data used for metabolic flux analysis

Directory of Open Access Journals (Sweden)

Poskar C Hart

2012-11-01

Full Text Available Abstract Background Metabolic flux analysis has become an established method in systems biology and functional genomics. The most common approach for determining intracellular metabolic fluxes is to utilize mass spectrometry in combination with stable isotope labeling experiments. However, before the mass spectrometric data can be used it has to be corrected for biases caused by naturally occurring stable isotopes, by the analytical technique(s employed, or by the biological sample itself. Finally the MS data and the labeling information it contains have to be assembled into a data format usable by flux analysis software (of which several dedicated packages exist. Currently the processing of mass spectrometric data is time-consuming and error-prone requiring peak by peak cut-and-paste analysis and manual curation. In order to facilitate high-throughput metabolic flux analysis, the automation of multiple steps in the analytical workflow is necessary. Results Here we describe iMS2Flux, software developed to automate, standardize and connect the data flow between mass spectrometric measurements and flux analysis programs. This tool streamlines the transfer of data from extraction via correction tools to 13C-Flux software by processing MS data from stable isotope labeling experiments. It allows the correction of large and heterogeneous MS datasets for the presence of naturally occurring stable isotopes, initial biomass and several mass spectrometry effects. Before and after data correction, several checks can be performed to ensure accurate data. The corrected data may be returned in a variety of formats including those used by metabolic flux analysis software such as 13CFLUX, OpenFLUX and 13CFLUX2. Conclusion iMS2Flux is a versatile, easy to use tool for the automated processing of mass spectrometric data containing isotope labeling information. It represents the core framework for a standardized workflow and data processing. Due to its flexibility

Determination of symbiotic nitrogen fixation by labelling the soil atmosphere with sup(15)N sub(2) at low isotope enrichment

International Nuclear Information System (INIS)

Trivelin, P.C.O.

1982-01-01

A direct method to determine the total symbiotic nitrogen fixation during the leguminous plants cycles has been, developed, by labelling the soil atmosphere with sup(15)N sub(2) at low isotope enrichment, of about 1 atom % excess. The soil explored by the root system of leguminous plants was confined by means of a chamber in the field and by sealed pots in greenhouse experiments in order to maintain the soil air labelled with sup(15)N sub(2). The average sup(15)N concentration in the soil atmosphere, necessary to calculate dinitrogen fixation, was obtained by integration of the exponential functions of isotope dilution. Those functions were obtained by periodic sampling and analysis of the N sub(2) in the soil atmosphere. The field experiment with labelled atmosphere was carried out from the 22 sup(nd) to the 31 sup(st) day of the bean crop cycle and 5.5 mg N/plant (24% of total plant N) was derived from fixation. In pot experiments, under greenhouse conditions, integrated determination of fixation was made in Phaseolus beans (from the 19 sup(th) to the 67 sup(th) day from planting) and in soybeans (from the 24 sup(th) to the 70 sup(th) day from planting). The soil atmosphere was labelled with sup(15)N sub(2) in both cases. Average fixation obtained for Phaseolus beans was 80 mg N/plant (65% of total plant N) and for soybeans 265 mg N/plant (71% of total plant N). Evaluation of the basic concept of the isotope dilution method to determine nitrogen fixation in pots experiments, as proposed by Fried and Middelboe (1977) has also been made in the present paper. Simultaneous determinations of fixation in soybeans, using the isotope dilution method of Fried and Middelboe, natural variation of the sup(15)N/ sup(14)N ratios, and total-N differences, indicated the same results for pot experiments, harvested at the end of the plant cycle. (author)

Thermodynamic and structural study of two-dimensional phase transitions within films of molecules physi-sorbed on graphite; the role of orientational order in wetting and roughening phenomena

International Nuclear Information System (INIS)

Angerand, Francois

1987-01-01

Two-dimensional phase transitions within films physi-sorbed upon the basal face of graphite have been investigated using two experimental methods: volumetric measurements of adsorption isotherms and neutron diffraction. Our main objective was to study the role played by orientational order in these films, its influence on their thermodynamic and structural properties, and its significance in wetting and roughening phenomena, which are indirectly accessible from adsorption studies. A comparative study of the adsorption isotherms of two molecules having comparable dipole moments, NH 3 and C 2 H 3 F, discloses very dissimilar behaviours, due to the fact that hydrogen bonding is involved in the interaction between NH 3 , but not C 2 H 3 F, molecules. The impossibility of such a bond for the interaction of the adsorbate with the substrate results in a poor cohesion energy of the NH 3 ad-film in comparison with those of its bulk condensed phases. The situation is opposite for the film of C 2 H 3 F which behaves almost as a rare gas film. From multilayer adsorption isotherms of CO it is shown that graphite (0001) is perfectly wet by the plastic (orientationally disordered) crystal phase, β-CO, whereas it is incompletely wet by the low-temperature crystal phase α-CO, in which the molecules are orientationally ordered. The critical temperatures of two-dimensional condensation have been measured for the successive ad-layers, up to the fifth. They seem to converge towards a value of 65 K, which we consider as representing the temperature of the roughening transition of the (0001) face of β-CO. A neutron diffraction study of the monolayers of N 2 O and C(CD 3 ) 4 adsorbed on graphite has been carried out. For N 2 O our results suggest a structure more involved than conjectured. For C(CD 3 ) 4 we have evidence for a triple point at 178 K. The crystal monolayer has a compact hexagonal structure. (author) [fr

Efficient production of isotopically labeled proteins by cell-free synthesis: A practical protocol

Energy Technology Data Exchange (ETDEWEB)

Torizawa, Takuya; Shimizu, Masato [Crest, Jst (Japan); Taoka, Masato [Tokyo Metropolitan University, Graduate School of Science (Japan); Miyano, Hiroshi [Ajinomoto Co., Inc. Institute of Life Sciences (Japan); Kainosho, Masatsune [Crest, Jst (Japan)], E-mail: kainosho@nmr.chem.metro-u.ac.jp

2004-11-15

We provide detailed descriptions of our refined protocols for the cell-free production of labeled protein samples for NMR spectroscopy. These methods are efficient and overcome two critical problems associated with the use of conventional Escherichia coli extract systems. Endogenous amino acids normally present in E. coli S30 extracts dilute the added labeled amino acids and degrade the quality of NMR spectra of the target protein. This problem was solved by altering the protocol used in preparing the S30 extract so as to minimize the content of endogenous amino acids. The second problem encountered in conventional E. coli cell-free protein production is non-uniformity in the N-terminus of the target protein, which can complicate the NMR spectra. This problem was solved by adding a DNA sequence to the construct that codes for a cleavable N-terminal peptide tag. Addition of the tag serves to increase the yield of the protein as well as to ensure a homogeneous protein product following tag cleavage. We illustrate the method by describing its stepwise application to the production of calmodulin samples with different stable isotope labeling patterns for NMR analysis.

Efficient production of isotopically labeled proteins by cell-free synthesis: A practical protocol

International Nuclear Information System (INIS)

Torizawa, Takuya; Shimizu, Masato; Taoka, Masato; Miyano, Hiroshi; Kainosho, Masatsune

2004-01-01

We provide detailed descriptions of our refined protocols for the cell-free production of labeled protein samples for NMR spectroscopy. These methods are efficient and overcome two critical problems associated with the use of conventional Escherichia coli extract systems. Endogenous amino acids normally present in E. coli S30 extracts dilute the added labeled amino acids and degrade the quality of NMR spectra of the target protein. This problem was solved by altering the protocol used in preparing the S30 extract so as to minimize the content of endogenous amino acids. The second problem encountered in conventional E. coli cell-free protein production is non-uniformity in the N-terminus of the target protein, which can complicate the NMR spectra. This problem was solved by adding a DNA sequence to the construct that codes for a cleavable N-terminal peptide tag. Addition of the tag serves to increase the yield of the protein as well as to ensure a homogeneous protein product following tag cleavage. We illustrate the method by describing its stepwise application to the production of calmodulin samples with different stable isotope labeling patterns for NMR analysis

Closing the gap between T-cell life span estimates from stable isotope-labeling studies in mice and humans

NARCIS (Netherlands)

Westera, Liset; Drylewicz, Julia; den Braber, Ineke; Mugwagwa, Tendai; van der Maas, Iris; Kwast, Lydia; Volman, Thomas; van de Weg-Schrijver, Elise H. R.; Bartha, István; Spierenburg, Gerrit; Gaiser, Koos; Ackermans, Mariëtte T.; Asquith, Becca; de Boer, Rob J.; Tesselaar, Kiki; Borghans, José A. M.

2013-01-01

Quantitative knowledge of the turnover of different leukocyte populations is a key to our understanding of immune function in health and disease. Much progress has been made thanks to the introduction of stable isotope labeling, the state-of-the-art technique for in vivo quantification of cellular

Influence of boron on ferrite formation in copper-added spheroidal graphite cast iron

Directory of Open Access Journals (Sweden)

Ying Zou

2014-07-01

Full Text Available This paper reviews the original work of the authors published recently, describing the influence of B on the matrix of the Cuadded spheroidal graphite cast iron. The effect of Cu has been corrected as a ferrite formation promoter in the matrix of the grey cast iron by the usage of high-purity material. Also, this paper focuses on the ferrite formation and the observation of the Cu distribution in the B-added and B-free Cu-containing spheroidal graphite cast iron. The Cu film on the spheroidal graphite can be successfully observed in the B-free sample using a special etching method. However, in the B-added sample, no Cu film could be found, while the secondary graphite was formed on the surface of the spheroidal graphite. The interaction between B and Cu is stressed as a peculiar phenomenon by the employment of a contrast experiment of B and Mn. The heat treatment could make Cu precipitate more significantly in the eutectic cells and in the matrix in the form of large Cu particles because of the limited solubility of Cu.

Isotopic labeling as a tool to establish intramolecular vibrational coupling: The reaction of 2-propanol on Mo(110)

International Nuclear Information System (INIS)

Uvdal, P.; Wiegand, B.C.; Serafin, J.G.; Friend, C.M.

1992-01-01

The reactions of 2-propanol on Mo(110) were investigated using temperature programmed reaction, high resolution electron energy loss, and x-ray photoelectron spectroscopies. 2-Propanol forms 2-propoxide upon adsorption at 120 K on Mo(110). The 2-propoxide intermediate deoxygenates via selective γ C--H bond scission to eliminate propene as well as C--O bond hydrogenolysis to form trace amounts of propane. The C--O bond of 2-propoxide is estimated to be nearly perpendicular to the surface. Selective isotopic labeling was used to establish the coupling between the C--O stretch and modes associated with the hydrocarbon framework. The degree of coupling was strongly affected by bonding to the surface, primarily due to weakening of the C--O bond when 2-propoxide is bound to Mo(110). Selective isotopic labeling was, therefore, essential in making vibrational assignments and in identifying key reaction steps. Only a small kinetic isotope effect was observed during reaction of (CD 3 )(CH 3 )CHOH, consistent with a substantial component of C--O bond breaking in the transition state for propene elimination. Coupling of the C--O stretch to motion of the methyl group is also suggested to be important in the transition state for propene elimination

An isotope approach based on C-13 pulse-chase labelling vs. the root trenching method to separate heterotrophic and autotrophic respiration in cultivated peatlands

Energy Technology Data Exchange (ETDEWEB)

Biasi, C.; Pitkamaki, A. S.; Tavi, N. M.; Koponen, H. T.; Martikainen, P. J. [Univ.of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], e-mail: christina.biasi@uef.fi

2012-11-01

We tested an isotope method based on C-13 pulse-chase labelling for determining the fractional contribution of soil microbial respiration to overall soil respiration in an organic soil (cutaway peatland, eastern Finland), cultivated with the bioenergy crop, reed canary grass. The plants were exposed to CO{sub 2}-13 for five hours and the label was thereafter determined in CO{sub 2} derived from the soil-root system. A two-pool isotope mixing model was used to separate sources of respiration. The isotopic approach showed that a minimum of 50% of the total CO{sub 2} originated from soil-microbial respiration. Even though the method uses undisturbed soil-plant systems, it has limitations concerning the experimental determination of the true isotopic signal of all components contributing to autotrophic respiration. A trenching experiment which was comparatively conducted resulted in a 71% fractional contribution of soil-microbial respiration. This value was likely overestimated. Further studies are needed to evaluate critically the output from these two partitioning approaches. (orig.)

Stable isotope applications in biomolecular structure and mechanisms. A meeting to bring together producers and users of stable-isotope-labeled compounds to assess current and future needs

International Nuclear Information System (INIS)

Trewhella, J.; Cross, T.A.; Unkefer, C.J.

1994-12-01

Knowledge of biomolecular structure is a prerequisite for understanding biomolecular function, and stable isotopes play an increasingly important role in structure determination of biological molecules. The first Conference on Stable Isotope Applications in Biomolecular Structure and Mechanisms was held in Santa Fe, New Mexico, March 27--31, 1994. More than 120 participants from 8 countries and 44 institutions reviewed significant developments, discussed the most promising applications for stable isotopes, and addressed future needs and challenges. Participants focused on applications of stable isotopes for studies of the structure and function of proteins, peptides, RNA, and DNA. Recent advances in NMR techniques neutron scattering, EPR, and vibrational spectroscopy were highlighted in addition to the production and synthesis of labeled compounds. This volume includes invited speaker and poster presentations as well as a set of reports from discussion panels that focused on the needs of the scientific community and the potential roles of private industry, the National Stable Isotope Resource, and the National High Magnetic Field Laboratory in serving those needs. This is the leading abstract. Individual papers are processed separately for the database

Stable isotope applications in biomolecular structure and mechanisms. A meeting to bring together producers and users of stable-isotope-labeled compounds to assess current and future needs

Energy Technology Data Exchange (ETDEWEB)

Trewhella, J.; Cross, T.A.; Unkefer, C.J. [eds.

1994-12-01

Knowledge of biomolecular structure is a prerequisite for understanding biomolecular function, and stable isotopes play an increasingly important role in structure determination of biological molecules. The first Conference on Stable Isotope Applications in Biomolecular Structure and Mechanisms was held in Santa Fe, New Mexico, March 27--31, 1994. More than 120 participants from 8 countries and 44 institutions reviewed significant developments, discussed the most promising applications for stable isotopes, and addressed future needs and challenges. Participants focused on applications of stable isotopes for studies of the structure and function of proteins, peptides, RNA, and DNA. Recent advances in NMR techniques neutron scattering, EPR, and vibrational spectroscopy were highlighted in addition to the production and synthesis of labeled compounds. This volume includes invited speaker and poster presentations as well as a set of reports from discussion panels that focused on the needs of the scientific community and the potential roles of private industry, the National Stable Isotope Resource, and the National High Magnetic Field Laboratory in serving those needs. This is the leading abstract. Individual papers are processed separately for the database.

Segmental isotope labeling of proteins for NMR structural study using a protein S tag for higher expression and solubility

International Nuclear Information System (INIS)

Kobayashi, Hiroshi; Swapna, G. V. T.; Wu, Kuen-Phon; Afinogenova, Yuliya; Conover, Kenith; Mao, Binchen; Montelione, Gaetano T.; Inouye, Masayori

2012-01-01

A common obstacle to NMR studies of proteins is sample preparation. In many cases, proteins targeted for NMR studies are poorly expressed and/or expressed in insoluble forms. Here, we describe a novel approach to overcome these problems. In the protein S tag-intein (PSTI) technology, two tandem 92-residue N-terminal domains of protein S (PrS 2 ) from Myxococcus xanthus is fused at the N-terminal end of a protein to enhance its expression and solubility. Using intein technology, the isotope-labeled PrS 2 -tag is replaced with non-isotope labeled PrS 2 -tag, silencing the NMR signals from PrS 2 -tag in isotope-filtered 1 H-detected NMR experiments. This method was applied to the E. coli ribosome binding factor A (RbfA), which aggregates and precipitates in the absence of a solubilization tag unless the C-terminal 25-residue segment is deleted (RbfAΔ25). Using the PrS 2 -tag, full-length well-behaved RbfA samples could be successfully prepared for NMR studies. PrS 2 (non-labeled)-tagged RbfA (isotope-labeled) was produced with the use of the intein approach. The well-resolved TROSY-HSQC spectrum of full-length PrS 2 -tagged RbfA superimposes with the TROSY-HSQC spectrum of RbfAΔ25, indicating that PrS 2 -tag does not affect the structure of the protein to which it is fused. Using a smaller PrS-tag, consisting of a single N-terminal domain of protein S, triple resonance experiments were performed, and most of the backbone 1 H, 15 N and 13 C resonance assignments for full-length E. coli RbfA were determined. Analysis of these chemical shift data with the Chemical Shift Index and heteronuclear 1 H– 15 N NOE measurements reveal the dynamic nature of the C-terminal segment of the full-length RbfA protein, which could not be inferred using the truncated RbfAΔ25 construct. CS-Rosetta calculations also demonstrate that the core structure of full-length RbfA is similar to that of the RbfAΔ25 construct.

Lifetimes of organic photovoltaics: Using TOF-SIMS and ¹⁸O₂ isotopic labelling to characterise chemical degradation mechanisms

DEFF Research Database (Denmark)

Norrman, K.; Krebs, Frederik C

2006-01-01

The lifetimes of organic photovoltaic cells based on conjugated polymer materials were studied. The device geometry was glass:ITO:PEDOT:PSS:C-12-PSV:C-60:aluminium. To characterise and elucidate the parts of the degradation mechanisms induced by molecular oxygen, 1802 isotopic labelling was emplo......The lifetimes of organic photovoltaic cells based on conjugated polymer materials were studied. The device geometry was glass:ITO:PEDOT:PSS:C-12-PSV:C-60:aluminium. To characterise and elucidate the parts of the degradation mechanisms induced by molecular oxygen, 1802 isotopic labelling...

A graphite foam reinforced by graphite particles

Energy Technology Data Exchange (ETDEWEB)

Zhu, J.J.; Wang, X.Y.; Guo, L.F.; Wang, Y.M.; Wang, Y.P.; Yu, M.F.; Lau, K.T.T. [DongHua University, Shanghai (China). College of Material Science and Engineering

2007-11-15

Graphite foam was obtained after carbonization and graphitization of a pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite particles in a high pressure and temperature chamber. The graphite foam possessed high mechanical strength and exceptional thermal conductivity after adding the graphite particles. Experimental results showed that the thermal conductivity of modified graphite foam reached 110W/m K, and its compressive strength increased from 3.7 MPa to 12.5 MPa with the addition of 5 wt% graphite particles. Through the microscopic observation, it was also found that fewer micro-cracks were formed in the cell wall of the modified foam as compared with pure graphite foam. The graphitization degree of modified foam reached 84.9% and the ligament of graphite foam exhibited high alignment after carbonization at 1200{sup o}C for 3 h and graphitization at 3000{sup o}C for 10 min.

Surface and electron emission properties of hydrogen-free diamond-like carbon films investigated by atomic force microscopy

International Nuclear Information System (INIS)

Liu Dongping; Zhang, Sam; Ong, S.-E.; Benstetter, Guenther; Du Hejun

2006-01-01

In this study, we have deposited hydrogen-free diamond-like carbon (DLC) films by using DC magnetron sputtering of graphite target at various r.f. bias voltages. Surface and nanoscale emission properties of these DLC films have been investigated using a combination of atomic force microscopy (AFM)-based nanowear tests and conducting-AFM, by simultaneously measuring the topography and the conductivity of the samples. Nanowear tests show that these DLC films are covered with the thin (1.5-2.0 nm) graphite-like layers at surfaces. Compared to the film bulk structure, the graphite-like surface layers are more conductive. The graphite-like surface layers significantly influence the electron emission properties of these films. Low-energy carbon species can be responsible for the formation of graphite-like surface layers. Nanoscale electron emission measurements have revealed the inhomogeneous emission nature of these films. The low-field emission from these films can be attributed to the existence of sp 2 -configured nanoclusters inside the films

Graphite

Science.gov (United States)

Robinson, Gilpin R.; Hammarstrom, Jane M.; Olson, Donald W.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Graphite is a form of pure carbon that normally occurs as black crystal flakes and masses. It has important properties, such as chemical inertness, thermal stability, high electrical conductivity, and lubricity (slipperiness) that make it suitable for many industrial applications, including electronics, lubricants, metallurgy, and steelmaking. For some of these uses, no suitable substitutes are available. Steelmaking and refractory applications in metallurgy use the largest amount of produced graphite; however, emerging technology uses in large-scale fuel cell, battery, and lightweight high-strength composite applications could substantially increase world demand for graphite.Graphite ores are classified as “amorphous” (microcrystalline), and “crystalline” (“flake” or “lump or chip”) based on the ore’s crystallinity, grain-size, and morphology. All graphite deposits mined today formed from metamorphism of carbonaceous sedimentary rocks, and the ore type is determined by the geologic setting. Thermally metamorphosed coal is the usual source of amorphous graphite. Disseminated crystalline flake graphite is mined from carbonaceous metamorphic rocks, and lump or chip graphite is mined from veins in high-grade metamorphic regions. Because graphite is chemically inert and nontoxic, the main environmental concerns associated with graphite mining are inhalation of fine-grained dusts, including silicate and sulfide mineral particles, and hydrocarbon vapors produced during the mining and processing of ore. Synthetic graphite is manufactured from hydrocarbon sources using high-temperature heat treatment, and it is more expensive to produce than natural graphite.Production of natural graphite is dominated by China, India, and Brazil, which export graphite worldwide. China provides approximately 67 percent of worldwide output of natural graphite, and, as the dominant exporter, has the ability to set world prices. China has significant graphite reserves, and

A Cost-effective Amino-acid-type Selective Isotope Labeling of Proteins Expressed in Leishmania tarentolae

Czech Academy of Sciences Publication Activity Database

Foldynová-Trantírková, Silvie; Matulová, J.; Dötsch, V.; Löhr, F.; Cirstea, I.; Alexandov, K.; Breitling, R.; Lukeš, Julius; Trantírek, Lukáš

2009-01-01

Roč. 26, č. 6 (2009), s. 755-761 ISSN 0739-1102 R&D Projects: GA ČR GP204/08/P585; GA AV ČR 1QS600220554; GA AV ČR KAN200100801; GA MŠk 2B06129 Institutional research plan: CEZ:AV0Z60220518 Keywords : NMR * isotope labeling * protein expression * Leishmania * low-level enrichment Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.124, year: 2009

Quantitative imaging of subcellular metabolism with stable isotopes and multi-isotope imaging mass spectrometry

Science.gov (United States)

Steinhauser, Matthew L.; Lechene, Claude P.

2014-01-01

Multi-isotope imaging mass spectrometry (MIMS) is the quantitative imaging of stable isotope labels in cells with a new type of secondary ion mass spectrometer (NanoSIMS). The power of the methodology is attributable to (i) the immense advantage of using non-toxic stable isotope labels, (ii) high resolution imaging that approaches the resolution of usual transmission electron microscopy and (iii) the precise quantification of label down to 1 part-per-million and spanning several orders of magnitude. Here we review the basic elements of MIMS and describe new applications of MIMS to the quantitative study of metabolic processes including protein and nucleic acid synthesis in model organisms ranging from microbes to humans. PMID:23660233

Effect of load, area of contact, and contact stress on the tribological properties of polyimide bonded graphite fluoride films

Science.gov (United States)

Fusaro, R. L.

1981-01-01

A pin-on-disk type of friction and wear apparatus was used to study the effect of load, contact stress and rider area of contact on the friction and wear properties of polyimide-bonded graphite fluoride films. Different rider area contacts were obtained by initially generating flats (with areas of 0.0035, 0.0071, 0.0145, and 0.0240 cm) on 0.476-cm radius hemispherically-tipped riders. Different projected contact stresses were obtained by applying loads of 2.5-to 58.8-N to the flats. Two film wear mechanisms were observed. The first was found to be a linear function of contact stress and was independent of rider area of contact. The second was found to increase exponentially as the stress increased. The second also appeared to be a function of rider contact area. Wear equations for each mechanism were empirically derived from the experimental data. In general, friction coefficients increased with increasing rider contact area and with sliding duration. This was related to the build-up of thick rider transfer films.

Directed self-assembled crystalline oligomer domains on graphene and graphite

International Nuclear Information System (INIS)

Balzer, Frank; Sun, Rong; Henrichsen, Henrik H; Klarskov, Mikkel B; Booth, Timothy J; Bøggild, Peter; Parisi, Jürgen; Schiek, Manuela

2014-01-01

We observe the formation of thin films of fibre-like aggregates from the prototypical organic semiconductor molecule para-hexaphenylene (p-6P) on graphite thin flakes and on monolayer graphene. Using atomic force microscopy, scanning electron microscopy, x-ray diffraction, polarized fluorescence microscopy, and bireflectance microscopy, the molecular orientations on the surface are deduced and correlated to both the morphology as well as to the high-symmetry directions of the graphitic surface: the molecules align with their long axis at ±11° with respect to a high-symmetry direction. The results show that the graphene surface can be used as a growth substrate to direct the self-assembly of organic molecular thin films and nanofibres, both with and without lithographical processing. (paper)

The labelling of Nanocoll[reg] with [111In] for dual-isotope scanning

International Nuclear Information System (INIS)

Mitterhauser, Markus; Wadsak, Wolfgang; Key Mien, Leonhard-; Eidherr, Harald; Roka, Sebastian; Zettinig, Georg; Angelberger, Peter; Viernstein, Helmut; Kletter, Kurt; Dudczak, Robert

2003-01-01

Visualization and biopsy of sentinel lymph nodes play an important role in planning and controlling the therapy of breast cancer. Hitherto two methods--scintigraphy or gamma probe detection after injection of [ 99m Tc]-nanocolloids and visual detection after injection of patent blue dye--are used routinely. There are no conclusive publications elucidating such important parameters as injection site, injection method and colloidal parameters. The present work aims to label Nanocoll[reg] with [ 111 In] to provide an alternative method, a simultaneous one-compound dual-isotope application. Methods: [ 111 In]-Indiumchloride was buffered with acetate and transferred to the nanocolloid. The colloid labelling reaction was complete after 30 min and filtrated through 100 nm Nuclepore[reg] filters. Results: Incorporation yield of [ 111 In]-Indium into the nanocolloid was nearly quantitative, the step associated with the major loss of activity was the particle sizing with a mean yield of 55%. Conclusion: The presented method allows for the routine supply of [ 111 In]-nanocolloids. Size-filtered [ 111 In]-Nanocoll[reg] shows the same particle size range as [ 99m Tc]-Nanocoll[reg

An economic approach to efficient isotope labeling in insect cells using homemade {sup 15}N-, {sup 13}C- and {sup 2}H-labeled yeast extracts

Energy Technology Data Exchange (ETDEWEB)

Opitz, Christian; Isogai, Shin; Grzesiek, Stephan, E-mail: Stephan.Grzesiek@unibas.ch [University of Basel, Focal Area Structural Biology and Biophysics, Biozentrum (Switzerland)

2015-07-15

Heterologous expression of proteins in insect cells is frequently used for crystallographic structural studies due to the high yields even for challenging proteins requiring the eukaryotic protein processing capabilities of the host. However for NMR studies, the need for isotope labeling poses extreme challenges in eukaryotic hosts. Here, we describe a robust method to achieve uniform protein {sup 15}N and {sup 13}C labeling of up to 90 % in baculovirus-infected insect cells. The approach is based on the production of labeled yeast extract, which is subsequently supplemented to insect cell growth media. The method also allows deuteration at levels of >60 % without decrease in expression yield. The economic implementation of the labeling procedures into a standard structural biology laboratory environment is described in a step-by-step protocol. Applications are demonstrated for a variety of NMR experiments using the Abelson kinase domain, GFP, and the beta-1 adrenergic receptor as examples. Deuterated expression of the latter provides spectra of very high quality of a eukaryotic G-protein coupled receptor.

A nano-graphite cold cathode for an energy-efficient cathodoluminescent light source

Directory of Open Access Journals (Sweden)

Alexander N. Obraztsov

2013-08-01

Full Text Available The development of new types of light sources is necessary in order to meet the growing demands of consumers and to ensure an efficient use of energy. The cathodoluminescence process is still under-exploited for light generation because of the lack of cathodes suitable for the energy-efficient production of electron beams and appropriate phosphor materials. In this paper we propose a nano-graphite film material as a highly efficient cold cathode, which is able to produce high intensity electron beams without energy consumption. The nano-graphite film material was produced by using chemical vapor deposition techniques. Prototypes of cathodoluminescent lamp devices with a construction optimized for the usage of nano-graphite cold cathodes were developed, manufactured and tested. The results indicate prospective advantages of this type of lamp and the possibility to provide advanced power efficiency as well as enhanced spectral and other characteristics.

Effect of friction on oxidative graphite intercalation and high-quality graphene formation.

Science.gov (United States)

Seiler, Steffen; Halbig, Christian E; Grote, Fabian; Rietsch, Philipp; Börrnert, Felix; Kaiser, Ute; Meyer, Bernd; Eigler, Siegfried

2018-02-26

Oxidative wet-chemical delamination of graphene from graphite is expected to become a scalable production method. However, the formation process of the intermediate stage-1 graphite sulfate by sulfuric acid intercalation and its subsequent oxidation are poorly understood and lattice defect formation must be avoided. Here, we demonstrate film formation of micrometer-sized graphene flakes with lattice defects down to 0.02% and visualize the carbon lattice by transmission electron microscopy at atomic resolution. Interestingly, we find that only well-ordered, highly crystalline graphite delaminates into oxo-functionalized graphene, whereas other graphite grades do not form a proper stage-1 intercalate and revert back to graphite upon hydrolysis. Ab initio molecular dynamics simulations show that ideal stacking and electronic oxidation of the graphite layers significantly reduce the friction of the moving sulfuric acid molecules, thereby facilitating intercalation. Furthermore, the evaluation of the stability of oxo-species in graphite sulfate supports an oxidation mechanism that obviates intercalation of the oxidant.

Correlation between chemical, crystallographic and spectroscopic parameters in graphite thermometry applied to a contact aureole of La Soledad monzogranite (Venezuelan Andes

Directory of Open Access Journals (Sweden)

K. Reategui

2017-11-01

Full Text Available Graphite samples from a metamorphic contact aureole between phyllites of the Cerro Azul Association (Palaeozoic and La Soledad Monzogranite, in the Venezuelan Andes, were studied by chemical (% inorganic carbon and isotopic distribution, crystallographic (DRX and spectroscopic (Raman techniques in order to assess changes in the graphite in the vicinity of the contact, the correlation between the different parameters, and the determination of the higher temperature reached by the host rock during igneous intrusion. The δ13C reached less negative values near the monzogranite, caused by devolatilization; the graphite present just in contact with the pluton experienced retrograde recrystallization, which causes a shift towards more negative values. The calculated degree of graphitization intervals (GD = 53–80 corresponds to a well-structured mineral with ordered packaging. The peak metamorphic temperature at the contact was calculated from crystallographic (XRD and spectroscopic (Raman parameters with great agreement in both techniques, registering the 528 ± 16 and 526 ± 20 ºC respectively. The metapelitic rocks reached the Cordierite Zone (cordierite + biotite + muscovite in the contact aureole where the graphite is well ordered and in hexagonal microtexture. Factors such as fluid activity and the subsequent retrograde recrystallization have an effect on isotopic redistributions after the intrusive event, as well as on the crystallinity change rate with the temperature, avoiding a clear correlation between the isotopic variations of 13C in graphite and the temperature.

Development of chemical isotope labeling liquid chromatography mass spectrometry for silkworm hemolymph metabolomics

International Nuclear Information System (INIS)

Shen, Weifeng; Han, Wei; Li, Yunong; Meng, Zhiqi; Cai, Leiming; Li, Liang

2016-01-01

Silkworm (Bombyx mori) is a very useful target insect for evaluation of endocrine disruptor chemicals (EDCs) due to mature breeding techniques, complete endocrine system and broad basic knowledge on developmental biology. Comparative metabolomics of silkworms with and without EDC exposure offers another dimension of studying EDCs. In this work, we report a workflow on metabolomic profiling of silkworm hemolymph based on high-performance chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS) and demonstrate its application in studying the metabolic changes associated with the pesticide dichlorodiphenyltrichloroethane (DDT) exposure in silkworm. Hemolymph samples were taken from mature silkworms after growing on diet that contained DDT at four different concentrations (1, 0.1, 0.01, 0.001 ppm) as well as on diet without DDT as controls. They were subjected to differential "1"2C-/"1"3C-dansyl labeling of the amine/phenol submetabolome, LC-UV quantification of the total amount of labeled metabolites for sample normalization, and LC-MS detection and relative quantification of individual metabolites in comparative samples. The total concentration of labeled metabolites did not show any significant change between four DDT-treatment groups and one control group. Multivariate statistical analysis of the metabolome data set showed that there was a distinct metabolomic separation between the five groups. Out of the 2044 detected peak pairs, 338 and 1471 metabolites have been putatively identified against the HMDB database and the EML library, respectively. 65 metabolites were identified by the dansyl library searching based on the accurate mass and retention time. Among the 65 identified metabolites, 33 positive metabolites had changes of greater than 1.20-fold or less than 0.83-fold in one or more groups with p-value of smaller than 0.05. Several useful biomarkers including serine, methionine, tryptophan, asymmetric dimethylarginine, N

Development of chemical isotope labeling liquid chromatography mass spectrometry for silkworm hemolymph metabolomics

Energy Technology Data Exchange (ETDEWEB)

Shen, Weifeng [Key Laboratory of Detection for Pesticide Residues, Ministry of Agriculture (China); Sericultural Research Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou (China); Han, Wei; Li, Yunong [Department of Chemistry, University of Alberta, Edmonton, Alberta (Canada); Meng, Zhiqi [Sericultural Research Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou (China); Cai, Leiming, E-mail: cailm@mail.zaas.ac.cn [Institute of Quality and Standard for Agro-products, Zhejiang Academy of Agricultural Sciences, Hangzhou (China); Li, Liang, E-mail: Liang.Li@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta (Canada)

2016-10-26

Silkworm (Bombyx mori) is a very useful target insect for evaluation of endocrine disruptor chemicals (EDCs) due to mature breeding techniques, complete endocrine system and broad basic knowledge on developmental biology. Comparative metabolomics of silkworms with and without EDC exposure offers another dimension of studying EDCs. In this work, we report a workflow on metabolomic profiling of silkworm hemolymph based on high-performance chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS) and demonstrate its application in studying the metabolic changes associated with the pesticide dichlorodiphenyltrichloroethane (DDT) exposure in silkworm. Hemolymph samples were taken from mature silkworms after growing on diet that contained DDT at four different concentrations (1, 0.1, 0.01, 0.001 ppm) as well as on diet without DDT as controls. They were subjected to differential {sup 12}C-/{sup 13}C-dansyl labeling of the amine/phenol submetabolome, LC-UV quantification of the total amount of labeled metabolites for sample normalization, and LC-MS detection and relative quantification of individual metabolites in comparative samples. The total concentration of labeled metabolites did not show any significant change between four DDT-treatment groups and one control group. Multivariate statistical analysis of the metabolome data set showed that there was a distinct metabolomic separation between the five groups. Out of the 2044 detected peak pairs, 338 and 1471 metabolites have been putatively identified against the HMDB database and the EML library, respectively. 65 metabolites were identified by the dansyl library searching based on the accurate mass and retention time. Among the 65 identified metabolites, 33 positive metabolites had changes of greater than 1.20-fold or less than 0.83-fold in one or more groups with p-value of smaller than 0.05. Several useful biomarkers including serine, methionine, tryptophan, asymmetric dimethylarginine, N

Effects of Oxidation on Oxidation-Resistant Graphite

Energy Technology Data Exchange (ETDEWEB)

Windes, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Rebecca [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carroll, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-05-01

The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

Development of uniformly stable isotope labeling system in higher plants for hetero-nuclear NMR experiments in vitro and in vivo

International Nuclear Information System (INIS)

Kikuchi, J.

2005-01-01

Full text: Novel methods for measurement of living systems are making new breakthroughs in life science. In the era of the metabolome (analysis of all measurable metabolites), a MS-based approach is considered to be the major technology, whereas a NMR-based method is recognized as minor technology due to its low sensitivity. Therefore, my laboratory is currently focusing to develop novel methodologies for an NMR-based metabolomics. This will be achieved by uniform stable isotope labeling of higher plants allowing application of multi-dimensional NMR experiments used in protein structure determination. Using these novel methods, I will analyze the dynamic molecular networks inside tissues. Especially, use of stable isotope labeling methods has enormous advantage for discrimination of incorporated or de novo synthesized compounds. Furthermore, potentiality of in vivo-NMR metabolomics will be discussed in the conference. (author)

Dry Sliding Wear Behavior of Spark Plasma Sintered Fe-Based Bulk Metallic Glass/Graphite Composites

Directory of Open Access Journals (Sweden)

Xiulin Ji

2016-09-01

Full Text Available Bulk metallic glass (BMG and BMG-graphite composites were fabricated using spark plasma sintering at the sintering temperature of 575 °C and holding time of 15 min. The sintered composites exhibited partial crystallization and the presence of distributed porosity and graphite particles. The effect of graphite reinforcement on the tribological properties of the BMG/graphite composites was investigated using dry ball-on-disc sliding wear tests. The reinforcement of graphite resulted in a reduction in both the wear rate and the coefficient of friction as compared to monolithic BMG samples. The wear surfaces of BMG/graphite composites showed regions of localized wear loss due to microcracking and fracture, as was also the case with the regions covered with graphite-rich protective film due to smearing of pulled off graphite particles.

Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach

International Nuclear Information System (INIS)

Huang, Zhi-Yong; Xie, Hong; Cao, Ying-Lan; Cai, Chao; Zhang, Zhi

2014-01-01

Highlights: • Large amounts of exogenous Pb were found to distribute in reducible fractions. • Very few of exogenous Pb were found to distribute in acid-extractable fractions. • More than 60% of exogenous Pb in rhizosphere soils lost after planting. • Isotopic labeling method and SEP enable to explore Pb bioavailability in soil. -- Abstract: The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of 206 Pb, the contamination of exogenous Pb 2+ ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60–85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60–66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation

Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhi-Yong, E-mail: zhyhuang@jmu.edu.cn [College of Bioengineering, Jimei University, Xiamen 361021 (China); Xie, Hong [College of Bioengineering, Jimei University, Xiamen 361021 (China); Shandong Vocational Animal Science and Veterinary College, Weifang 261061 (China); Cao, Ying-Lan [College of Bioengineering, Jimei University, Xiamen 361021 (China); Cai, Chao [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Zhang, Zhi [College of Bioengineering, Jimei University, Xiamen 361021 (China)

2014-02-15

Highlights: • Large amounts of exogenous Pb were found to distribute in reducible fractions. • Very few of exogenous Pb were found to distribute in acid-extractable fractions. • More than 60% of exogenous Pb in rhizosphere soils lost after planting. • Isotopic labeling method and SEP enable to explore Pb bioavailability in soil. -- Abstract: The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of {sup 206}Pb, the contamination of exogenous Pb{sup 2+} ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60–85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60–66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation.

Dansylation isotope labeling liquid chromatography mass spectrometry for parallel profiling of human urinary and fecal submetabolomes

Energy Technology Data Exchange (ETDEWEB)

Su, Xiaoling [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Wang, Nan [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Chen, Deying [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Li, Yunong [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Lu, Yingfeng [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Huan, Tao [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Xu, Wei [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Li, Liang, E-mail: Liang.Li@ualberta.ca [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China); Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Li, Lanjuan, E-mail: ljli@zju.edu.cn [State Key Laboratory and Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003 (China)

2016-01-15

Human urine and feces can be non-invasively collected for metabolomics-based disease biomarker discovery research. Because urinary and fecal metabolomes are thought to be different, analysis of both biospecimens may generate a more comprehensive metabolomic profile that can be better related to the health state of an individual. Herein we describe a method of using differential chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS) for parallel metabolomic profiling of urine and feces. Dansylation labeling was used to quantify the amine/phenol submetabolome changes among different samples based on {sup 12}C-labeling of individual samples and {sup 13}C-labeling of a pooled urine or pooled feces and subsequent analysis of the {sup 13}C-/{sup 12}C-labeled mixture by LC-MS. The pooled urine and pooled feces are further differentially labeled, mixed and then analyzed by LC-MS in order to relate the metabolite concentrations of the common metabolites found in both biospecimens. This method offers a means of direct comparison of urinary and fecal submetabolomes. We evaluated the analytical performance and demonstrated the utility of this method in the analysis of urine and feces collected daily from three healthy individuals for 7 days. On average, 2534 ± 113 (n = 126) peak pairs or metabolites could be detected from a urine sample, while 2507 ± 77 (n = 63) peak pairs were detected from a fecal sample. In total, 5372 unique peak pairs were detected from all the samples combined; 3089 and 3012 pairs were found in urine and feces, respectively. These results reveal that the urine and fecal metabolomes are very different, thereby justifying the consideration of using both biospecimens to increase the probability of finding specific biomarkers of diseases. Furthermore, the CIL LC-MS method described can be used to perform parallel quantitative analysis of urine and feces, resulting in more complete coverage of the human metabolome

Dansylation isotope labeling liquid chromatography mass spectrometry for parallel profiling of human urinary and fecal submetabolomes

International Nuclear Information System (INIS)

Su, Xiaoling; Wang, Nan; Chen, Deying; Li, Yunong; Lu, Yingfeng; Huan, Tao; Xu, Wei; Li, Liang; Li, Lanjuan

2016-01-01

Human urine and feces can be non-invasively collected for metabolomics-based disease biomarker discovery research. Because urinary and fecal metabolomes are thought to be different, analysis of both biospecimens may generate a more comprehensive metabolomic profile that can be better related to the health state of an individual. Herein we describe a method of using differential chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS) for parallel metabolomic profiling of urine and feces. Dansylation labeling was used to quantify the amine/phenol submetabolome changes among different samples based on "1"2C-labeling of individual samples and "1"3C-labeling of a pooled urine or pooled feces and subsequent analysis of the "1"3C-/"1"2C-labeled mixture by LC-MS. The pooled urine and pooled feces are further differentially labeled, mixed and then analyzed by LC-MS in order to relate the metabolite concentrations of the common metabolites found in both biospecimens. This method offers a means of direct comparison of urinary and fecal submetabolomes. We evaluated the analytical performance and demonstrated the utility of this method in the analysis of urine and feces collected daily from three healthy individuals for 7 days. On average, 2534 ± 113 (n = 126) peak pairs or metabolites could be detected from a urine sample, while 2507 ± 77 (n = 63) peak pairs were detected from a fecal sample. In total, 5372 unique peak pairs were detected from all the samples combined; 3089 and 3012 pairs were found in urine and feces, respectively. These results reveal that the urine and fecal metabolomes are very different, thereby justifying the consideration of using both biospecimens to increase the probability of finding specific biomarkers of diseases. Furthermore, the CIL LC-MS method described can be used to perform parallel quantitative analysis of urine and feces, resulting in more complete coverage of the human metabolome. - Highlights: • A

Double-label autoradiographic deoxyglucose method for sequential measurement of regional cerebral glucose utilization

Energy Technology Data Exchange (ETDEWEB)

Redies, C; Diksic, M; Evans, A C; Gjedde, A; Yamamoto, Y L

1987-08-01

A new double-label autoradiographic glucose analog method for the sequential measurement of altered regional cerebral metabolic rates for glucose in the same animal is presented. This method is based on the sequential injection of two boluses of glucose tracer labeled with two different isotopes (short-lived /sup 18/F and long-lived /sup 3/H, respectively). An operational equation is derived which allows the determination of glucose utilization for the time period before the injection of the second tracer; this equation corrects for accumulation and loss of the first tracer from the metabolic pool occurring after the injection of the second tracer. An error analysis of this operational equation is performed. The double-label deoxyglucose method is validated in the primary somatosensory (''barrel'') cortex of the anesthetized rat. Two different rows of whiskers were stimulated sequentially in each rat; the two periods of stimulation were each preceded by an injection of glucose tracer. After decapitation, dried brain slices were first exposed, in direct contact, to standard X-ray film and then to uncoated, ''tritium-sensitive'' film. Results show that the double-label deoxyglucose method proposed in this paper allows the quantification and complete separation of glucose utilization patterns elicited by two different stimulations sequentially applied in the same animal.

Synthesizing labeled compounds

International Nuclear Information System (INIS)

London, R.E.; Matwiyoff, N.A.; Unkefer, C.J.; Walker, T.E.

1983-01-01

A metabolic study is presented of the chemical reactions provided by isotopic labeling and NMR spectroscopy. Synthesis of 13 C-labeled D-glucose, a 6-carbon sugar, involves adding a labeled nitrile group to the 5-carbon sugar D-arabinose by reaction with labeled hydrogen cyanide. The product of this reaction is then reduced and hydrolyzed to a mixture of the labeled sugars. The two sugars are separated by absorption chromotography. The synthesis of 13 C-labeled L-tyrosine, an amino acid, is also presented

In Vivo Isotopic Labeling of Symbiotic Bacteria Involved in Cellulose Degradation and Nitrogen Recycling within the Gut of the Forest Cockchafer (Melolontha hippocastani).

Science.gov (United States)

Alonso-Pernas, Pol; Bartram, Stefan; Arias-Cordero, Erika M; Novoselov, Alexey L; Halty-deLeon, Lorena; Shao, Yongqi; Boland, Wilhelm

2017-01-01

The guts of insects harbor symbiotic bacterial communities. However, due to their complexity, it is challenging to relate a specific symbiotic phylotype to its corresponding function. In the present study, we focused on the forest cockchafer ( Melolontha hippocastani ), a phytophagous insect with a dual life cycle, consisting of a root-feeding larval stage and a leaf-feeding adult stage. By combining in vivo stable isotope probing (SIP) with 13 C cellulose and 15 N urea as trophic links, with Illumina MiSeq (Illumina-SIP), we unraveled bacterial networks processing recalcitrant dietary components and recycling nitrogenous waste. The bacterial communities behind these processes change between larval and adult stages. In 13 C cellulose-fed insects, the bacterial families Lachnospiraceae and Enterobacteriaceae were isotopically labeled in larvae and adults, respectively. In 15 N urea-fed insects, the genera Burkholderia and Parabacteroides were isotopically labeled in larvae and adults, respectively. Additionally, the PICRUSt-predicted metagenome suggested a possible ability to degrade hemicellulose and to produce amino acids of, respectively, 13 C cellulose- and 15 N urea labeled bacteria. The incorporation of 15 N from ingested urea back into the insect body was confirmed, in larvae and adults, by isotope ratio mass spectrometry (IRMS). Besides highlighting key bacterial symbionts of the gut of M. hippocastani , this study provides example on how Illumina-SIP with multiple trophic links can be used to target microorganisms embracing different roles within an environment.

In Vivo Isotopic Labeling of Symbiotic Bacteria Involved in Cellulose Degradation and Nitrogen Recycling within the Gut of the Forest Cockchafer (Melolontha hippocastani

Directory of Open Access Journals (Sweden)

Pol Alonso-Pernas

2017-10-01

Full Text Available The guts of insects harbor symbiotic bacterial communities. However, due to their complexity, it is challenging to relate a specific symbiotic phylotype to its corresponding function. In the present study, we focused on the forest cockchafer (Melolontha hippocastani, a phytophagous insect with a dual life cycle, consisting of a root-feeding larval stage and a leaf-feeding adult stage. By combining in vivo stable isotope probing (SIP with 13C cellulose and 15N urea as trophic links, with Illumina MiSeq (Illumina-SIP, we unraveled bacterial networks processing recalcitrant dietary components and recycling nitrogenous waste. The bacterial communities behind these processes change between larval and adult stages. In 13C cellulose-fed insects, the bacterial families Lachnospiraceae and Enterobacteriaceae were isotopically labeled in larvae and adults, respectively. In 15N urea-fed insects, the genera Burkholderia and Parabacteroides were isotopically labeled in larvae and adults, respectively. Additionally, the PICRUSt-predicted metagenome suggested a possible ability to degrade hemicellulose and to produce amino acids of, respectively, 13C cellulose- and 15N urea labeled bacteria. The incorporation of 15N from ingested urea back into the insect body was confirmed, in larvae and adults, by isotope ratio mass spectrometry (IRMS. Besides highlighting key bacterial symbionts of the gut of M. hippocastani, this study provides example on how Illumina-SIP with multiple trophic links can be used to target microorganisms embracing different roles within an environment.

Hydrogen adsorption on and solubility in graphites

International Nuclear Information System (INIS)

Kanashenko, S.L.; Wampler, W.R.

1996-01-01

The experimental data on adsorption and solubility of hydrogen isotopes in graphite over a wide range of temperatures and pressures are reviewed. Langmuir adsorption isotherms are proposed for the hydrogen-graphite interaction. The entropy and enthalpy of adsorption are estimated, allowing for effects of relaxation of dangling sp 2 bonds. Three kinds of traps are proposed: edge carbon atoms of interstitial loops with an adsorption enthalpy relative to H 2 gas of -4.4 eV/H 2 (unrelaxed, Trap 1), edge carbon atoms at grain surfaces with an adsorption enthalpy of -2.3 eV/H 2 (relaxed, Trap 2), and basal plane adsorption sites with an enthalpy of +2.43 eV/H 2 (Trap 3). The adsorption capacity of different types of graphite depends on the concentration of traps which depends on the crystalline microstructure of the material. The number of potential sites for the 'true solubility' (Trap 3) is assumed to be about one site per carbon atom in all types of graphite, but the endothermic character of this solubility leads to a negligible H inventory compared to the concentration of hydrogen in type 1 and type 2 traps for temperatures and gas pressures used in the experiments. Irradiation with neutrons or carbon atoms increases the concentration of type 1 and type 2 traps from about 20 and 200 appm respectively for unirradiated (POCO AXF-5Q) graphite to about 1500 and 5000 appm, respectively, at damage levels above 1 dpa. (orig.)

Protection of nuclear graphite toward fluoride molten salt by glassy carbon deposit

International Nuclear Information System (INIS)

Bernardet, V.; Gomes, S.; Delpeux, S.; Dubois, M.; Guerin, K.; Avignant, D.; Renaudin, G.; Duclaux, L.

2009-01-01

Molten salt reactor represents one of the promising future Generation IV nuclear reactors families where the fuel, a liquid molten fluoride salt, is circulating through the graphite reactor core. The interactions between nuclear graphite and fluoride molten salt and also the graphite surface protection were investigated in this paper by powder X-ray diffraction, micro-Raman spectroscopy and scanning electron microscopy coupled with X-ray microanalysis. Nuclear graphite discs were covered by two kinds of protection deposit: a glassy carbon coating and a double coating of pyrolitic carbon/glassy carbon. Different behaviours have been highlighted according to the presence and the nature of the coated protection film. Intercalation of molten salt between the graphite layers did not occur. Nevertheless the molten salt adhered more or less to the surface of the graphite disc, filled more or less the graphite surface porosity and perturbed more or less the graphite stacking order at the disc surface. The behaviour of unprotected graphite was far to be satisfactory after two days of immersion of graphite in molten salt at 500 deg. C. The best protection of the graphite disc surface, with the maximum of inertness towards molten salt, has been obtained with the double coating of pyrolitic carbon/glassy carbon

Stable isotope N-phosphoryl amino acids labeling for quantitative profiling of amine-containing metabolites using liquid chromatography mass spectrometry.

Science.gov (United States)

Zhang, Shanshan; Shi, Jinwen; Shan, Changkai; Huang, Chengting; Wu, Yile; Ding, Rong; Xue, Yuhua; Liu, Wen; Zhou, Qiang; Zhao, Yufen; Xu, Pengxiang; Gao, Xiang

2017-07-25

Stable isotope chemical labeling liquid chromatography-mass spectrometry (LC-MS) is a powerful strategy for comprehensive metabolomics profiling, which can improve metabolites coverage and quantitative information for exploration of metabolic regulation in complex biological systems. In the current work, a novel stable isotope N-phosphoryl amino acids labeling strategy (SIPAL) has been successful developed for quantitative profiling of amine-containing metabolites in urine based on organic phosphorus chemistry. Two isotopic reagents, 16 O 2 - and 18 O 2 -N-diisopropyl phosphoryl l-alanine N-hydroxysuccinimide esters ( 16 O/ 18 O-DIPP-L-Ala-NHS), were firstly synthesized in high yields for labeling the amine-containing metabolites. The performance of SIPAL strategy was tested by analyzing standard samples including 20 l-amino acids, 10 d-amino acids and small peptides by using LC-MS. We observed highly efficient and selective labeling for SIPAL strategy within 15 min in a one-pot derivatization reaction under aqueous reaction conditions. The introduction of a neutral phosphate group at N-terminus can increase the proton affinity and overall hydrophobicity of targeted metabolites, leading to the better ionization efficiency in electrospray ionization processes and chromatographic separations of hydrophilic metabolites on reversed-phase column. Furthermore, the chiral metabolites, such as d-amino acids, could be converted to diastereomers after SIPAL and successfully separated on regular reversed-phase column. The chirality of labeled enantiomers can be determined by using different detection methods such as 31 P NMR, UV, and MS, demonstrating the potential application of SIPAL strategy. In addition, absolute quantification of chiral metabolites in biological samples can be easily achieved by using SIPAL strategy. For this purpose, urine samples collected from a healthy volunteer were analyzed by using LC-ESI-Orbitrap MS. Over 300 pairs of different amine

Labeling pharmaceuticals with radioactive isotopes. Technical progress report, December 1, 1975--November 30, 1976

International Nuclear Information System (INIS)

Blau, M.; Bender, M.A.

1976-01-01

The purpose of this research is to prepare iodo- and bromo-aliphatic amino acid analogs labeled with γ-emitting isotopes ( 131 I, 123 I and 77 Br) for possible use as pancreas localizing agents. Studies on the halogen exchange reaction (I- for Cl-) for the synthesis of β-iodo-α-aminobutyric acid (a valine analog) have suggested that the iodo compound was formed initially. However, the desired compound cannot be isolated because of its chemical instability. Distribution studies in rats with the crude halogen exchange reaction mixture confirmed this finding. Studies on the addition of hydrogen iodine to allylglycine under various conditions for the synthesis of γ-iodo-α-aminopentanoic acid (a leucine analog) suffered the same obstacle; the chemical instability of the desired iodo compound precludes isolation and characterization. Convinced that the iodo analogs were too unstable for use as practical localizing agents, we turned to the possible use of Br for CH 3 substituted amino acids. The 14 C labeled β-bromo-α-aminobutyric acid methyl ester was synthesized. This methyl ester will be hydrolyzed and the distribution of free amino acid will be studied. Labeled with 77 Br this compound might be useful for pancreas localization

Direct isotope determination of isotopically labelled lipids by field desorption mass spectrometry

International Nuclear Information System (INIS)

Lehmann, W.D.; Kessler, M.

1982-01-01

Lipids labelled with deuterium or carbon-14 have been investigated by field desorption mass spectrometry for determination of their degree of labelling. This application is demonstrated for free fatty acids, cholesterol, cholesteryl esters, triglycerides, and L-α-phosphatidylcholines. Comparison of the molecular ion groups of the non-labelled and of the labelled compounds enables a fast and reliable determination of the degree of labelling. For multiply labelled compounds the label distribution is also obtained from the molecular ion group. In addition, for cholesteryl esters and for phosphatidylcholines structurally significant fragment ions provide information about the position of the label. Several hundred nanograms of the compound are typically required for a single analysis with a relative standard error of 0.5-2% in the value calculated for atom% hydrogen-2 or for the specific carbon-14 activity. (orig.) [de

Stable isotope labeling, in vivo, of D- and L-tryptophan pools in lemna gibba and the low incorporation of label into indole-3-acetic acid

International Nuclear Information System (INIS)

Baldi, B.G.; Maher, B.R.; Slovin, J.P.; Cohen, J.D.

1991-01-01

The authors present evidence that the role of tryptophan and other potential intermediates in the pathways that could lead to indole derivatives needs to be reexamined. Two lines of Lemna gibba were tested for uptake of [ 15 N-indole]-labeled tryptophan isomers and incorporation of that label into free indole-3-acetic acid (IAA). Both lines required levels of L-[ 15 N]tryptophan 2 to 3 orders of magnitude over endogenous levels in order to obtain measurable incorporation of label into IAA. Labeled L-tryptophan was extractable from plant tissue after feeding and showed no measurable isomerization into D-tryptophan. D-[ 15 N]trytophan supplied to Lemna at rates of approximately 400 times excess of endogenous D-tryptophan levels (to yield an isotopic enrichment equal to that which allowed detection of the incorporation of L-tryptophan into IAA), did not result in measurable incorporation of label into free IAA. These results demonstrate that L-tryptophan is a more direct precursor to IAA than the D isomer and suggest (a) that the availability of tryptophan in vivo is not a limiting factor in the biosynthesis of IAA, thus implying that other regulatory mechanisms are in operation and (b) that L-tryptophan also may not be a primary precursor to IAA in plants

Extrinsic labelling of staple food crops with isotopic iron does not consistently result in full equilibration: Revisiting the methodology

Science.gov (United States)

Extrinsic isotopic labeling of food Fe has been used for over 50 years to measure Fe absorption. This method is based on the assumption that complete equilibration occurs between the extrinsic and the intrinsic Fe prior to intestinal absorption. The present study tested this assumption via use of in...

Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

Energy Technology Data Exchange (ETDEWEB)

Capan, I., E-mail: inci.capan@gmail.com [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Tarimci, C., E-mail: Celik.Tarimci@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Ankara (Turkey); Erdogan, M., E-mail: merdogan@balikesir.edu.tr [Balikesir University, Faculty of Art and Sciences, Department of Physics, Cagis Campus, 10145 Balikesir (Turkey); Hassan, A.K., E-mail: A.Hassan@shu.ac.uk [Materials and Engineering Research Institute, Sheffield Hallam University, Sheaf Building, Pond Street, Sheffield S1 1WB (United Kingdom)

2009-05-05

In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

Characterisation and vapour sensing properties of spin coated thin films of anthracene labelled PMMA polymer

International Nuclear Information System (INIS)

Capan, I.; Tarimci, C.; Erdogan, M.; Hassan, A.K.

2009-01-01

In the present article thin films of poly (methyl methacrylate) (PMMA) polymer labelled with anthracene (Ant-PMMA) prepared by spin coating are characterised by UV-visible spectroscopy, surface plasmon resonance (SPR), spectroscopic ellipsometry (SE) and Atomic Force Microscopy (AFM) and their organic vapour sensing properties are investigated. Ant-PMMA films' thickness are determined by performing theoretical fitting to experimental data measured using SPR and SE. Results obtained show that the spin-cast films are of good uniformity with an average thickness of 6-8 nm. Organic vapour sensing properties are studied using SPR technique during exposures to different volatile organic compounds (VOCs). Ant-PMMA films' response to the selected VOCs has been examined in terms of solubility parameters and molar volumes of the solvents, and the films were found to be largely sensitive to benzene vapour compared to other studied analytes.

Isotope effects: definitions and consequences for pharmacologic studies

International Nuclear Information System (INIS)

Van Langenhove, A.

1986-01-01

The use of stable isotope-labeled compounds for pharmacologic studies requires careful consideration of the nature of the stable isotope label (2H, 13C, 15N, 18O) and its position of incorporation in the molecule. When deuterium is used, improper positioning can lead to significant primary isotope effects. Primary isotope effects occur when the breaking of the bond to the heavy isotope is the rate-limiting step in a reaction (or metabolic transformation). A reaction will proceed slower for the molecule with the heavy isotope label because of the mass difference between the light and the heavy isotope. In addition to these primary isotope effects, smaller but nevertheless important secondary isotope effects, physicochemical isotope effects, active hydrogen/deuterium exchange, or isotope effects associated with either the enzyme-catalyzed biotransformation or the mass spectrometric ionization and fragmentation can be operative. In mechanistic studies, isotope effects are used to their advantage; however, in pharmacokinetic studies, the occurrence of isotope effects can lead to grossly misleading biologic and analytic results: the metabolism of the drug will differ when in vivo isotope effects are operative, and isotope effects occurring during the analysis procedure will obscure the true metabolic profile of the drug

Synthesis of isotopically labelled salicylates

International Nuclear Information System (INIS)

Hawkins, D.R.; Pryor, R.W.

1981-01-01

[ 13 C-carboxyl]Salicylic acid has been prepared by carbonation of 2-benzyloxybromobenzene followed by reductive debenzylation. Deuterium and tritium labelled salicylic acid and 2 H 2 / 13 C-salicylic acid were prepared by reduction of the 3,5-dibromo derivatives using Raney Ni-Al. Deuterium labelled salicylic acid containing up to four deuterium atoms was prepared by catalytic exchange with Raney Ni-Al in 5% NaOD/D 2 O. (author)

From position-specific isotope labeling towards soil fluxomics: a novel toolbox to assess the microbial impact on biogeochemical cycles

Science.gov (United States)

Apostel, C.; Dippold, M. A.; Kuzyakov, Y.

2015-12-01

Understanding the microbial impact on C and nutrient cycles is one of the most important challenges in terrestrial biogeochemistry. Transformation of low molecular weight organic substances (LMWOS) is a key step in all biogeochemical cycles because 1) all high molecular substances pass the LMWOS pool during their degradation and 2) only LMWOS can be taken up by microorganisms intact. Thus, the transformations of LMWOS are dominated by biochemical pathways of the soil microorganisms. Thus, understanding fluxes and transformations in soils requires a detailed knowledge on the microbial metabolic network and its control mechanism. Tracing C fate in soil by isotopes became on of the most applied and promising biogeochemistry tools but studies were nearly exclusively based on uniformly labeled substances. However, such tracers do not allow the differentiation of the intact use of the initial substances from its transformation to metabolites. The novel tool of position-specific labeling enables to trace molecule atoms separately and thus to determine the cleavage of molecules - a prerequisite for metabolic tracing. Position-specific labeling of basic metabolites and quantification of isotope incorporation in CO2 and bulk soil enabled following the basic metabolic pathways of microorganisms. However, the combination of position-specific 13C labeling with compound-specific isotope analysis of microbial biomarkers and metabolites like phospholipid fatty acids (PLFA) or amino sugars revealed new insights into the soil fluxome: First, it enables tracing specific anabolic pathways in diverse microbial communities in soils e.g. carbon starvation pathways versus pathways reflecting microbial growth. Second, it allows identification of specific pathways of individual functional microbial groups in soils in situ. Tracing metabolic pathways and understanding their regulating factors are crucial for soil C fluxomics i.e. the unravaling of the complex network of C transformations

Reliable LC-MS quantitative glycomics using iGlycoMab stable isotope labeled glycans as internal standards.

Science.gov (United States)

Zhou, Shiyue; Tello, Nadia; Harvey, Alex; Boyes, Barry; Orlando, Ron; Mechref, Yehia

2016-06-01

Glycans have numerous functions in various biological processes and participate in the progress of diseases. Reliable quantitative glycomic profiling techniques could contribute to the understanding of the biological functions of glycans, and lead to the discovery of potential glycan biomarkers for diseases. Although LC-MS is a powerful analytical tool for quantitative glycomics, the variation of ionization efficiency and MS intensity bias are influencing quantitation reliability. Internal standards can be utilized for glycomic quantitation by MS-based methods to reduce variability. In this study, we used stable isotope labeled IgG2b monoclonal antibody, iGlycoMab, as an internal standard to reduce potential for errors and to reduce variabililty due to sample digestion, derivatization, and fluctuation of nanoESI efficiency in the LC-MS analysis of permethylated N-glycans released from model glycoproteins, human blood serum, and breast cancer cell line. We observed an unanticipated degradation of isotope labeled glycans, tracked a source of such degradation, and optimized a sample preparation protocol to minimize degradation of the internal standard glycans. All results indicated the effectiveness of using iGlycoMab to minimize errors originating from sample handling and instruments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the cytotoxicity of carbon-based nanoparticles, diamond and graphite, in human glioblastoma and hepatoma cell lines

DEFF Research Database (Denmark)

Zakrzewska, Karolina Ewa; Samluk, Anna; Wierzbicki, Mateusz

2015-01-01

carbon based nanoparticles, diamond and graphite, on glioblastoma and hepatoma cells were compared. First, we confirmed previous results that diamond nanoparticles are practically nontoxic. Second, graphite nanoparticles exhibited a negative impact on glioblastoma, but not on hepatoma cells. The studied...... carbon nanoparticles could be a potentially useful tool for therapeutics delivery to the brain tissue with minimal side effects on the hepatocytes. Furthermore, we showed the influence of the nanoparticles on the stable, fluorescently labeled tumor cell lines and concluded that the labeled cells...

Scanning tunneling microscopy of hexagonal BN grown on graphite

International Nuclear Information System (INIS)

Fukumoto, H.; Hamada, T.; Endo, T.; Osaka, Y.

1991-01-01

The microscopic surface topography of thin BN x films grown on graphite by electron cyclotron resonance plasma chemical vapor deposition have been imaged with scanning tunneling microscopy in air. The scanning tunneling microscope has generated images of hexagonal BN with atomic resolution

Molecular dynamics simulation of chemical sputtering of hydrogen atom on layer structured graphite

International Nuclear Information System (INIS)

Ito, A.; Wang, Y.; Irle, S.; Morokuma, K.; Nakamura, H.

2008-10-01

Chemical sputtering of hydrogen atom on graphite was simulated using molecular dynamics. Especially, the layer structure of the graphite was maintained by interlayer intermolecular interaction. Three kinds of graphite surfaces, flat (0 0 0 1) surface, armchair (1 1 2-bar 0) surface and zigzag (1 0 1-bar 0) surface, are dealt with as targets of hydrogen atom bombardment. In the case of the flat surface, graphene layers were peeled off one by one and yielded molecules had chain structures. On the other hand, C 2 H 2 and H 2 are dominant yielded molecules on the armchair and zigzag surfaces, respectively. In addition, the interaction of a single hydrogen isotope on a single graphene is investigated. Adsorption, reflection and penetration rates are obtained as functions of incident energy and explain hydrogen retention on layered graphite. (author)

Analysis of the differentially expressed low molecular weight peptides in human serum via an N-terminal isotope labeling technique combining nano-liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Leng, Jiapeng; Zhu, Dong; Wu, Duojiao; Zhu, Tongyu; Zhao, Ningwei; Guo, Yinlong

2012-11-15

Peptidomics analysis of human serum is challenging due to the low abundance of serum peptides and interference from the complex matrix. This study analyzed the differentially expressed (DE) low molecular weight peptides in human serum integrating a DMPITC-based N-terminal isotope labeling technique with nano-liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (nano-LC/MALDI-MS). The workflow introduced a [d(6)]-4,6-dimethoxypyrimidine-2-isothiocyanate (DMPITC)-labeled mixture of aliquots from test samples as the internal standard. The spiked [d(0)]-DMPITC-labeled samples were separated by nano-LC then spotted on the MALDI target. Both quantitative and qualitative studies for serum peptides were achieved based on the isotope-labeled peaks. The DMPITC labeling technique combined with nano-LC/MALDI-MS not only minimized the errors in peptide quantitation, but also allowed convenient recognition of the labeled peptides due to the 6 Da mass difference. The data showed that the entire research procedure as well as the subsequent data analysis method were effective, reproducible, and sensitive for the analysis of DE serum peptides. This study successfully established a research model for DE serum peptides using DMPITC-based N-terminal isotope labeling and nano-LC/MALDI-MS. Application of the DMPITC-based N-terminal labeling technique is expected to provide a promising tool for the investigation of peptides in vivo, especially for the analysis of DE peptides under different biological conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Isotopic exchange between CO2 and H2O and labelling kinetics of photosynthetic oxygen

International Nuclear Information System (INIS)

Gerster, Richard

1971-01-01

The reaction of carbon dioxide with water has been studied by measuring the rate of oxygen exchange between C 18 O 2 and H 2 16 O. The mathematical treatment of the kinetics allows to determine with accuracy the diffusion flow between the gas and the liquid phase, in the same way as the CO 2 hydration rate. The velocity constant of this last process, whose value gives the in situ enzymatic activity of carbonic anhydrase, has been established in the case of chloroplast and Euglena suspensions and of aerial leaves. The study of the isotopic exchange between C 18 O 2 and a vegetable submitted to alternations of dark and light has allowed to calculate the isotopic abundance of the metabolized CO 2 whose value has been compared to that of the intracellular water and that of photosynthetic oxygen. In addition, a new method using 13 C 18 O 2 gives the means to measure with accuracy eventual isotopic effects. The labelling kinetics of the oxygen evolved by Euglena suspensions whose water has been enriched with 18 O have been established at different temperatures. (author) [fr

The mechanism of domain-wall structure formation in Ar-Kr submonolayer films on graphite

Directory of Open Access Journals (Sweden)

A. Patrykiejew

2014-12-01

Full Text Available Using Monte Carlo simulation method in the canonical ensemble, we have studied the commensurate-incommensurate transition in two-dimensional finite mixed clusters of Ar and Kr adsorbed on graphite basal plane at low temperatures. It has been demonstrated that the transition occurs when the argon concentration exceeds the value needed to cover the peripheries of the cluster. The incommensurate phase exhibits a similar domain-wall structure as observed in pure krypton films at the densities exceeding the density of a perfect (√3x√3R30º commensurate phase, but the size of commensurate domains does not change much with the cluster size. When the argon concentration increases, the composition of domain walls changes while the commensurate domains are made of pure krypton. We have constructed a simple one-dimensional Frenkel-Kontorova-like model that yields the results being in a good qualitative agreement with the Monte Carlo results obtained for two-dimensional systems.

Cross-Course Collaboration in the Undergraduate Chemistry Curriculum: Isotopic Labeling with Sodium Borodeuteride in the Introductory Organic Chemistry Laboratory

Science.gov (United States)

Kjonaas, Richard A.; Fitch, Richard W.; Noll, Robert J.

2017-01-01

A microscale isotopic labeling experiment is described for the introductory organic chemistry laboratory course wherein half of the students use sodium borohydride (NaBH[subscript 4]) and the other half use sodium borodeuteride (NaBD[subscript 4]) to reduce acetophenone to 1-phenylethanol and then compare spectral data. The cost is reasonable, and…

Isotope exchange reactions of the hydrogen H-5 of selected pyrimidine derivatives and the preparation of tritium-labeled pyrimidines

Czech Academy of Sciences Publication Activity Database

Dračínský, Martin; Jansa, Petr; Elbert, Tomáš

2011-01-01

Roč. 76, č. 12 (2011), s. 1567-1577 ISSN 0010-0765 R&D Projects: GA AV ČR KJB400550903; GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : isotopic labeling * NMR spectroscopy * nucleobases * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

Hydrogen content and density in nanocrystalline carbon films of a predominant diamond character

International Nuclear Information System (INIS)

Hoffman, A.; Heiman, A.; Akhvlediani, R.; Lakin, E.; Zolotoyabko, E.; Cyterman, C.

2003-01-01

Nanocrystalline carbon films possessing a prevailing diamond or graphite character, depending on substrate temperature, can be deposited from a methane hydrogen mixture by the direct current glow discharge plasma chemical vapor deposition method. While at a temperature of ∼880 deg. C, following the formation of a thin precursor graphitic film, diamond nucleation occurs and a nanodiamond film grows, at higher and lower deposition temperatures the films maintain their graphitic character. In this study the hydrogen content, density and nanocrystalline phase composition of films deposited at various temperatures are investigated. We aim to elucidate the role of hydrogen in nanocrystalline films with a predominant diamond character. Secondary ion mass spectroscopy revealed a considerable increase of the hydrogen concentration in the films that accompanies the growth of nanodiamond. It correlates with near edge x-ray adsorption spectroscopy measurements, that showed an appearance of spectroscopic features associated with the diamond structure, and with a substantial increase of the film density detected by x-ray reflectivity. Electron energy loss spectroscopy showed that nanocrystalline diamond films can be deposited from a CH 4 /H 2 mixture with hydrogen concentration in the 80%-95% range. For a deposition temperature of 880 deg. C, the highest diamond character of the films was found for a hydrogen concentration of 91% of H 2 . The deposition temperature plays an important role in diamond formation, strongly influencing the content of adsorbed hydrogen with an optimum at 880 deg. C. It is suggested that diamond nucleation and growth of the nanodiamond phase is driven by densification of the deposited graphitic films which results in high local compressive stresses. Nanodiamond formation is accompanied by an increase of hydrogen concentration in the films. It is suggested that hydrogen retention is critical for stabilization of nanodiamond crystallites. At lower

Protein-based stable isotope probing.

Science.gov (United States)

Jehmlich, Nico; Schmidt, Frank; Taubert, Martin; Seifert, Jana; Bastida, Felipe; von Bergen, Martin; Richnow, Hans-Hermann; Vogt, Carsten

2010-12-01

We describe a stable isotope probing (SIP) technique that was developed to link microbe-specific metabolic function to phylogenetic information. Carbon ((13)C)- or nitrogen ((15)N)-labeled substrates (typically with >98% heavy label) were used in cultivation experiments and the heavy isotope incorporation into proteins (protein-SIP) on growth was determined. The amount of incorporation provides a measure for assimilation of a substrate, and the sequence information from peptide analysis obtained by mass spectrometry delivers phylogenetic information about the microorganisms responsible for the metabolism of the particular substrate. In this article, we provide guidelines for incubating microbial cultures with labeled substrates and a protocol for protein-SIP. The protocol guides readers through the proteomics pipeline, including protein extraction, gel-free and gel-based protein separation, the subsequent mass spectrometric analysis of peptides and the calculation of the incorporation of stable isotopes into peptides. Extraction of proteins and the mass fingerprint measurements of unlabeled and labeled fractions can be performed in 2-3 d.

Electrochemical deposition of carbon films on titanium in molten LiCl–KCl–K2CO3

International Nuclear Information System (INIS)

Song, Qiushi; Xu, Qian; Wang, Yang; Shang, Xujing; Li, Zaiyuan

2012-01-01

Electrodeposition of carbon films on the oxide-scale-coated titanium has been performed in a LiCl–KCl–K 2 CO 3 melt, which are characterized by scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis. The electrochemical process of carbon deposition is investigated by cyclic voltammetry on the graphite, titanium and oxide-scale-coated titanium electrodes. The particle-size-gradient carbon films over the oxide-scale-coated titanium can be achieved by electrodeposition under the controlled potentials for avoiding codeposition of lithium carbide. The deposited carbon films are comprised of micron-sized ‘quasi-spherical’ carbon particles with graphitized and amorphous phases. The cyclic voltammetry behavior on the graphite, titanium and oxide-scale-coated titanium electrodes shows that CO 3 2− ions are reduced most favorably on the graphite for the three electrodes. Lithium ions can discharge under the less negative potential on the electrode containing carbon compared with titanium electrode because of the formation of lithium carbide from the reaction between lithium and carbon. - Highlights: ► Carbon films are prepared on oxide-scale-coated titanium in a LiCl–KCl–K 2 CO 3 melt. ► The films comprise micron-size ‘quasi-spherical’ carbon particles. ► The films present particle-size-gradient. ► The particles contain graphitized and amorphous phases. ► The prepared carbon films are more electrochemically active than graphite.

Bioinspired photonic nanoarchitectures from graphitic thin films

Energy Technology Data Exchange (ETDEWEB)

Tamaska, I.; Dobrik, G.; Nemes-Incze, P.; Kertesz, K.; Horvath, E.; Mark, G.I.; Jaszi, T.; Neumann, P.; Horvath, Z.E.; Biro, L.P., E-mail: biro@mfa.kfki.h

2011-04-01

Bioinspired, regular, rectangular (with periodicities of 600 nm and 700 nm), and random (with average characteristic distances of 600 nm and 750 nm) two dimensional (2D) photonic nanoarchitectures of 60 nm thickness were produced in graphite by Focused Ion Beam (FIB) nanomachining and subsequent controlled oxidation. The color of the nanoarchitectures was modified by the conformal deposition of 90 nm Al{sub 2}O{sub 3}. The regular patterns generate iridescent colors, while the random ones exhibit a remarkably constant color with the variation of the illumination and viewing conditions.

Bioinspired photonic nanoarchitectures from graphitic thin films

International Nuclear Information System (INIS)

Tamaska, I.; Dobrik, G.; Nemes-Incze, P.; Kertesz, K.; Horvath, E.; Mark, G.I.; Jaszi, T.; Neumann, P.; Horvath, Z.E.; Biro, L.P.

2011-01-01

Bioinspired, regular, rectangular (with periodicities of 600 nm and 700 nm), and random (with average characteristic distances of 600 nm and 750 nm) two dimensional (2D) photonic nanoarchitectures of 60 nm thickness were produced in graphite by Focused Ion Beam (FIB) nanomachining and subsequent controlled oxidation. The color of the nanoarchitectures was modified by the conformal deposition of 90 nm Al 2 O 3 . The regular patterns generate iridescent colors, while the random ones exhibit a remarkably constant color with the variation of the illumination and viewing conditions.

Chemical Ligation of Folded Recombinant Proteins: Segmental Isotopic Labeling of Domains for NMR Studies

Science.gov (United States)

Xu, Rong; Ayers, Brenda; Cowburn, David; Muir, Tom W.

1999-01-01

A convenient in vitro chemical ligation strategy has been developed that allows folded recombinant proteins to be joined together. This strategy permits segmental, selective isotopic labeling of the product. The src homology type 3 and 2 domains (SH3 and SH2) of Abelson protein tyrosine kinase, which constitute the regulatory apparatus of the protein, were individually prepared in reactive forms that can be ligated together under normal protein-folding conditions to form a normal peptide bond at the ligation junction. This strategy was used to prepare NMR sample quantities of the Abelson protein tyrosine kinase-SH(32) domain pair, in which only one of the domains was labeled with 15N Mass spectrometry and NMR analyses were used to confirm the structure of the ligated protein, which was also shown to have appropriate ligand-binding properties. The ability to prepare recombinant proteins with selectively labeled segments having a single-site mutation, by using a combination of expression of fusion proteins and chemical ligation in vitro, will increase the size limits for protein structural determination in solution with NMR methods. In vitro chemical ligation of expressed protein domains will also provide a combinatorial approach to the synthesis of linked protein domains.

Systematic NMR Analysis of Stable Isotope Labeled Metabolite Mixtures in Plant and Animal Systems: Coarse Grained Views of Metabolic Pathways

Science.gov (United States)

Chikayama, Eisuke; Suto, Michitaka; Nishihara, Takashi; Shinozaki, Kazuo; Hirayama, Takashi; Kikuchi, Jun

2008-01-01

Background Metabolic phenotyping has become an important ‘bird's-eye-view’ technology which can be applied to higher organisms, such as model plant and animal systems in the post-genomics and proteomics era. Although genotyping technology has expanded greatly over the past decade, metabolic phenotyping has languished due to the difficulty of ‘top-down’ chemical analyses. Here, we describe a systematic NMR methodology for stable isotope-labeling and analysis of metabolite mixtures in plant and animal systems. Methodology/Principal Findings The analysis method includes a stable isotope labeling technique for use in living organisms; a systematic method for simultaneously identifying a large number of metabolites by using a newly developed HSQC-based metabolite chemical shift database combined with heteronuclear multidimensional NMR spectroscopy; Principal Components Analysis; and a visualization method using a coarse-grained overview of the metabolic system. The database contains more than 1000 1H and 13C chemical shifts corresponding to 142 metabolites measured under identical physicochemical conditions. Using the stable isotope labeling technique in Arabidopsis T87 cultured cells and Bombyx mori, we systematically detected >450 HSQC peaks in each 13C-HSQC spectrum derived from model plant, Arabidopsis T87 cultured cells and the invertebrate animal model Bombyx mori. Furthermore, for the first time, efficient 13C labeling has allowed reliable signal assignment using analytical separation techniques such as 3D HCCH-COSY spectra in higher organism extracts. Conclusions/Significance Overall physiological changes could be detected and categorized in relation to a critical developmental phase change in B. mori by coarse-grained representations in which the organization of metabolic pathways related to a specific developmental phase was visualized on the basis of constituent changes of 56 identified metabolites. Based on the observed intensities of 13C atoms of

High thermoelectric performance of graphite nanofibers.

Science.gov (United States)

Tran, Van-Truong; Saint-Martin, Jérôme; Dollfus, Philippe; Volz, Sebastian

2018-02-22

Graphite nanofibers (GNFs) have been demonstrated to be a promising material for hydrogen storage and heat management in electronic devices. Here, by means of first-principles and transport simulations, we show that GNFs can also be an excellent material for thermoelectric applications thanks to the interlayer weak van der Waals interaction that induces low thermal conductance and a step-like shape in the electronic transmission with mini-gaps, which are necessary ingredients to achieve high thermoelectric performance. This study unveils that the platelet form of GNFs in which graphite layers are perpendicular to the fiber axis can exhibit outstanding thermoelectric properties with a figure of merit ZT reaching 3.55 in a 0.5 nm diameter fiber and 1.1 in a 1.1 nm diameter one. Interestingly, by introducing 14 C isotope doping, ZT can even be enhanced up to more than 5, and more than 8 if we include the effect of finite phonon mean free path, which demonstrates the amazing thermoelectric potential of GNFs.

Methyl-coenzyme M reductase from methanogenic archaea: isotope effects on label exchange and ethane formation with the homologous substrate ethyl-coenzyme M.

Science.gov (United States)

Scheller, Silvan; Goenrich, Meike; Thauer, Rudolf K; Jaun, Bernhard

2013-10-09

Ethyl-coenzyme M (CH3CH2-S-CH2CH2-SO3(-), Et-S-CoM) serves as a homologous substrate for the enzyme methyl-coenzyme M reductase (MCR) resulting in the product ethane instead of methane. The catalytic reaction proceeds via an intermediate that already contains all six C-H bonds of the product. Because product release occurs after a second, rate-limiting step, many cycles of intermediate formation and reconversion to substrate occur before a substantial amount of ethane is released. In deuterated buffer, the intermediate becomes labeled, and C-H activation in the back reaction rapidly leads to labeled Et-S-CoM, which enables intermediate formation to be detected. Here, we present a comprehensive analysis of this pre-equilibrium. (2)H- and (13)C-labeled isotopologues of Et-S-CoM were used as the substrates, and the time course of each isotopologue was followed by NMR spectroscopy. A kinetic simulation including kinetic isotope effects allowed determination of the primary and α- and β-secondary isotope effects for intermediate formation and for the C-H/C-D bond activation in the ethane-containing intermediate. The values obtained are in accordance with those found for the native substrate Me-S-CoM (see preceding publication, Scheller, S.; Goenrich, M.; Thauer, R. K.; Jaun, B. J. Am. Chem. Soc. 2013, 135, DOI: 10.1021/ja406485z) and thus imply the same catalytic mechanism for both substrates. The experiment by Floss and co-workers, demonstrating a net inversion of configuration to chiral ethane with CH3CDT-S-CoM as the substrate, is compatible with the observed rapid isotope exchange if the isotope effects measured here are taken into account.

Influence of the lithium salt nature over the surface film formation on a graphite electrode in Li-ion batteries: An XPS study

International Nuclear Information System (INIS)

Leroy, S.; Martinez, H.; Dedryvere, R.; Lemordant, D.; Gonbeau, D.

2007-01-01

The formation of a passivation film (solid electrolyte interphase, SEI) at the surface of the negative electrode of full LiCoO 2 /graphite lithium-ion cells using different salts (LiBF 4 , LiPF 6 , LiTFSI, LiBETI) in carbonate solvents as electrolyte was investigated by X-ray photoelectron spectroscopy (XPS). The analyzes were carried out at different potential stages of the first cycle, showing the potential-dependent character of the surface film species formation and the specificity of each salt. At 3.8 V, for all salts, we have mainly identified carbonated species. Beyond this potential, the specific behavior of LiPF 6 was identified with a high LiF deposit, whereas for other salts, the formation process of the SEI appears controlled by the solvent decomposition of the electrolyte

Cell-free expression and stable isotope labelling strategies for membrane proteins

International Nuclear Information System (INIS)

Sobhanifar, Solmaz; Reckel, Sina; Junge, Friederike; Schwarz, Daniel; Kai, Lei; Karbyshev, Mikhail; Loehr, Frank; Bernhard, Frank; Doetsch, Volker

2010-01-01

Membrane proteins are highly underrepresented in the structural data-base and remain one of the most challenging targets for functional and structural elucidation. Their roles in transport and cellular communication, furthermore, often make over-expression toxic to their host, and their hydrophobicity and structural complexity make isolation and reconstitution a complicated task, especially in cases where proteins are targeted to inclusion bodies. The development of cell-free expression systems provides a very interesting alternative to cell-based systems, since it circumvents many problems such as toxicity or necessity for the transportation of the synthesized protein to the membrane, and constitutes the only system that allows for direct production of membrane proteins in membrane-mimetic environments which may be suitable for liquid state NMR measurements. The unique advantages of the cell-free expression system, including strong expression yields as well as the direct incorporation of almost any combination of amino acids with very little metabolic scrambling, has allowed for the development of a wide-array of isotope labelling techniques which facilitate structural investigations of proteins whose spectral congestion and broad line-widths may have earlier rendered them beyond the scope of NMR. Here we explore various labelling strategies in conjunction with cell-free developments, with a particular focus on α-helical transmembrane proteins which benefit most from such methods.

Evaluation of a radioisotope labelling technique for measuring bacterial adherence on fabrics

International Nuclear Information System (INIS)

Youlo Hsieh; Timm, Debra; Merry, Joanne

1986-01-01

A technique utilizing tritiated thymidine labelled bacteria to quantify bacteria on fabrics has been evaluated. Quenching or self-absorption of isotope solution and labelled bacteria suspension by some of the fabrics has been observed. The extents of self-absorption of both isotope and labelled bacteria solutions on various fabrics was found to be dependent upon the fiber contents, i.e. the chemical compositions, of the substrata. This observation confirms that reduction of scintillation efficiency or self-absorption does occur when radio-labelled substances in suspensions were measured with the presence of some fabrics. Cautions should be taken when radio-labelling techniques are applied to detect isotope-labelled micro-organisms or other substances which are in contact with fabrics in the form of solutions. However, when there is no excess and nonattached labelled bacteria in the aqueous surrounding of the fabric, scintillation counting efficiency of the labelled bacteria on all fabrics studied remained constant over a period of 8 h. This indicates that the application of the described isotope labelling procedure is appropriate for quantifying adherent bacteria on fibrous substrate. (author)

PLD prepared nanostructured Pt-CeO{sub 2} thin films containing ionic platinum

Energy Technology Data Exchange (ETDEWEB)

Vorokhta, M., E-mail: vorohtam@gmail.com [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Khalakhan, I.; Matolínová, I.; Nováková, J.; Haviar, S. [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Lančok, J.; Novotný, M. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague, Czhech Republic (Czech Republic); Yoshikawa, H. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Matolín, V. [Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic)

2017-02-28

Highlights: • Nanostructured Pt-CeO{sub 2} thin catalyst films were grown on plasma etched and non-etched carbon substrates by pulsed laser deposition. • The surface composition of the nanostructured Pt-CeO{sub 2} films was investigated by surface analysis techniques. • The effect of film roughening was separated from the effect of platinum-ceria atomic interactions. - Abstract: The composition of nanostructured Pt-CeO{sub 2} films on graphite substrates prepared by pulsed laser deposition has been investigated by means of hard X-ray photoelectron spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, and atomic force microscopy. The influence of morphology of the graphite substrates was investigated with respect to the relative concentrations of ionic and metallic Pt species in the films. It was found that the degree of Pt{sup 2+} enrichment is directly related to the surface morphology of graphite substrates. In particular, the deposition of Pt-CeO{sub 2} films on rough graphite substrate etched in oxygen plasma yielded nanostructured Pt-CeO{sub 2} catalyst films with high surface area and high Pt{sup 2+}/Pt{sup 0} ratio. The presented results demonstrate that PLD is a suitable method for the preparation of thin Pt-CeO{sub 2} catalyst films for fuel cell applications.

Chemical properties of various organic electrolytes for lithium rechargeable batteries. Pt. 1.. Characterization of passivating layer formed on graphite in alkyl carbonate solutions

Energy Technology Data Exchange (ETDEWEB)

Mori, Shoichiro; Asahina, Hitoshi; Suzuki, Hitoshi; Yonei, Ayako; Yokoto, Kiyomi [Tsukuba Research Center, Mitsubishi Chemical Corporation, Ibaraki (Japan)

1997-09-01

The characteristics and reaction mechanisms of the passivating film formed on the surface of graphite were investigated in ethylene carbonate-diethyl carbonate solutions containing LiClO{sub 4}, LiPF{sub 6} and LiN(SO{sub 2}CF{sub 3}){sub 2}. The electron consumption resulting on the irreversible capacity of graphite was almost equivalent to that used in the one-electron reduction of Li{sup +} found in the film. The electrochemical reactions in the first discharge process may be divided into the following steps: (i) `initial film formation step` from 1.4 to 0.55 V; (ii) `main film formation step` from 0.55 to 0.2 V, and (iii) `lithium intercalation step from 0.2 to 0.0 V. Most of the passivating film is formed together with the lithium intercalation reaction at step (ii). The passivating film formed at this step contained a significant amount of organic film such as EtOCO{sub 2}Li, (CH{sub 2}OCO{sub 2}Li){sub 2}, etc. Through the consecutive formation of passivating film at steps (i) and (ii), lithium intercalation into graphite proceeds smoothly without further decomposition of organic electrolyte. (orig.)

Synthesis and pharmacokinetics of thiacoccide labeled with tritium

International Nuclear Information System (INIS)

Shestakov, A.D.; Kaminskii, Yu.L.; Nurova, I.M.; Nikitina, V.N.; Zaionts, V.I.; Maksimova, O.V.; Mikhailov, G.A.

1986-01-01

To obtain information on the pharmacokinetics of thiacoccide, the authors effect the synthesis of an analog of thiacoccide, viz., the hydrochloride of 2-methyl-N-(2'-n-propyl-4'-aminopyrimid-5'-ylmethyl)pyridinium chloride (I) labeled with tritium. The simplest way to introduce a tritium label into (I) is by isotopic exchange of hydrogen of (I) with H 3 HO. Typical material obtained from isotopic exchange with water labeled with tritium is shown. The dynamics of 3 H distribution in the organism of the chick and the rate of its elimination on single administration of thiacoccide containing isotope in both the methyl group and in the pyridine ring are shown

Directed self-assembled crystalline oligomer domains on graphene and graphite

DEFF Research Database (Denmark)

Balzer, Frank; Henrichsen, Henrik Hartmann; Klarskov, Mikkel Buster

2014-01-01

We observe the formation of thin films of fibre-like aggregates from the prototypical organic semiconductor molecule para-hexaphenylene (p-6P) on graphite thin flakes and on monolayer graphene. Using atomic force microscopy, scanning electron microscopy, x-ray diffraction, polarized fluorescence...... show that the graphene surface can be used as a growth substrate to direct the self-assembly of organic molecular thin films and nanofibres, both with and without lithographical processing....

Special graphites

International Nuclear Information System (INIS)

Leveque, P.

1964-01-01

A large fraction of the work undertaken jointly by the Commissariat a l'Energie Atomique (CEA) and the Pechiney Company has been the improvement of the properties of nuclear pile graphite and the opening up of new fields of graphite application. New processes for the manufacture of carbons and special graphites have been developed: forged graphite, pyro-carbons, high density graphite agglomeration of graphite powders by cracking of natural gas, impervious graphites. The physical properties of these products and their reaction with various oxidising gases are described. The first irradiation results are also given. (authors) [fr

Labelled compounds. (Pt. B)

International Nuclear Information System (INIS)

Buncel, E.; Jones, J.R.

1991-01-01

Since the end of World War II there has been a tremendous increase in the number of compounds that have been synthesized with radioactive or stable isotopes. They have found application in many diverse fields, so much so, that hardly a single area in pure and applied science has not benefited. Not surprisingly it has been reflected in appearance of related publications. The early proceedings of the Symposia on Advances in Trace Methodology were soon followed by various Euratom sponsored meetings in which methods of preparing and storing labelled compounds featured prominently. In due course a resurgence of interest in stable isotopes, brought about by their greater availability (also lower cost) and partly by development of new techniques such as gas chromatography - mass spectrometry (gc-ms), led to the publication of proceedings of several successful conferences. More recently conferences dealing with the synthesis and applications of isotopes and isotopically labelled compounds have been established on a regular basis. In addition to the proceedings of conferences and journal publications individuals left their mark by producing definitive texts, usually on specific nuclides. Only the classic two volume publication of Murray and Williams (Organic syntheses with isotopes, New York 1985), now over 30 years old and out of print, attempted to do justice to several nuclides. With the large amount of work that has been undertaken since then it seems unlikely that an updated edition could be produced. The alternative strategy was to ask scientists currently active to review specific areas and this is the approach adopted in the present series of monographs. In this way it is intended to cover the broad advances that have been made in the synthesis and applications of isotopes and isotopically labelled compounds in the physical and biomedical sciences. (author). refs.; figs.; tabs

Dynamics of N₂O production pathways analyzed by ¹⁵N¹⁸O isotope labeling

DEFF Research Database (Denmark)

Jensen, Marlene Mark; Ma, Chun; Lavik, Gaute

Nitrous oxide production associated with biological nitrogen transformations can contribute substantially to the CO2 footprint of both man-made and natural systems, but the pathways and regulation of N2O production are poorly understood. We developed a 15N/18O dual isotope labelling technique...

Oleic acid-assisted exfoliated few layer graphene films as counter electrode in dye-sensitized solar cell

International Nuclear Information System (INIS)

Liu, Jincheng; Wang, Yinjie; Sun, Darren Delai

2012-01-01

Highlights: ► Few layer graphene was obtained by liquid exfoliation in oleic acid (OLA). ► The concentration of exfoliated few layer graphene is as high as 1.3 mg/mL. ► OLA-assisted graphite (OLA-G) film has high catalytic activity. ► A power conversion efficiency of 3.56% can be gained by DSSCs with the counter electrode of OLA-G film. - Abstract: We have demonstrated a facile sonication method to exfoliate graphite into few layer graphene with a high concentration of 1.3 mg/mL in oleic acid (OLA). The exfoliations of natural graphite in oleylamine (OA) and trioctylphosphine (TOP) are investigated as a comparison. The few layer graphene dispersion in OLA and the graphite nanoparticles in OA are confirmed by transmission electron microscopy (TEM) observation. The exfoliated graphene dispersion in OLA (OLA-G) and graphite dispersion in OA (OA-G) are fabricated into a film on the FTO substrate by the doctor-blading method. The morphology and catalytic activity in the redox couple regeneration of all the graphite films are examined by field emission scanning electron microscopy and cyclic voltammograms. The OLA-G films on FTO glass with few layer graphene flakes shows better catalytic activity than the OA-G films. The energy conversion efficiency of the cell with the OLA-G film as counter electrode reached 3.56%, which is 70% of dye-sensitized solar cell (DSSC) with the sputtering-Pt counter electrode under the same experimental condition.

Graphite nanoreinforcements in polymer nanocomposites

Science.gov (United States)

Fukushima, Hiroyuki

Nanocomposites composed of polymer matrices with clay reinforcements of less than 100 nm in size, are being considered for applications such as interior and exterior accessories for automobiles, structural components for portable electronic devices, and films for food packaging. While most nanocomposite research has focused on exfoliated clay platelets, the same nanoreinforcement concept can be applied to another layered material, graphite, to produce nanoplatelets and nanocomposites. Graphite is the stiffest material found in nature (Young's Modulus = 1060 GPa), having a modulus several times that of clay, but also with excellent electrical and thermal conductivity. The key to utilizing graphite as a platelet nanoreinforcement is in the ability to exfoliate this material. Also, if the appropriate surface treatment can be found for graphite, its exfoliation and dispersion in a polymer matrix will result in a composite with not only excellent mechanical properties but electrical properties as well, opening up many new structural applications as well as non-structural ones where electromagnetic shielding and high thermal conductivity are requirements. In this research, a new process to fabricate exfoliated nano-scale graphite platelets was established (Patent pending). The size of the resulted graphite platelets was less than 1 um in diameter and 10 nm in thickness, and the surface area of the material was around 100 m2/g. The reduction of size showed positive effect on mechanical properties of composites because of the increased edge area and more functional groups attached with it. Also various surface treatment techniques were applied to the graphite nanoplatelets to improve the surface condition. As a result, acrylamide grafting treatment was found to enhance the dispersion and adhesion of graphite flakes in epoxy matrices. The resulted composites showed better mechanical properties than those with commercially available carbon fibers, vapor grown carbon fibers

Improved graphite matrix for coated-particle fuel

International Nuclear Information System (INIS)

Schell, D.H.; Davidson, K.V.

1978-10-01

An experimental process was developed to incorporate coated fuel particles in an extruded graphite matrix. This structure, containing 41 vol% particles, had a high matrix density, >1.6 g/cm 3 , and a matrix conductivity three to four times that of a pitch-injected fuel rod at 1775 K. Experiments were conducted to determine the uniformity of particle loadings in extrusions. Irradiation specimens were supplied for five tests in the High-Fluence Isotope Reactor at the Oak Ridge National Laboratory

On structural identifiability analysis of the cascaded linear dynamic systems in isotopically non-stationary 13C labelling experiments.

Science.gov (United States)

Lin, Weilu; Wang, Zejian; Huang, Mingzhi; Zhuang, Yingping; Zhang, Siliang

2018-06-01

The isotopically non-stationary 13C labelling experiments, as an emerging experimental technique, can estimate the intracellular fluxes of the cell culture under an isotopic transient period. However, to the best of our knowledge, the issue of the structural identifiability analysis of non-stationary isotope experiments is not well addressed in the literature. In this work, the local structural identifiability analysis for non-stationary cumomer balance equations is conducted based on the Taylor series approach. The numerical rank of the Jacobian matrices of the finite extended time derivatives of the measured fractions with respect to the free parameters is taken as the criterion. It turns out that only one single time point is necessary to achieve the structural identifiability analysis of the cascaded linear dynamic system of non-stationary isotope experiments. The equivalence between the local structural identifiability of the cascaded linear dynamic systems and the local optimum condition of the nonlinear least squares problem is elucidated in the work. Optimal measurements sets can then be determined for the metabolic network. Two simulated metabolic networks are adopted to demonstrate the utility of the proposed method. Copyright © 2018 Elsevier Inc. All rights reserved.

Method for producing dustless graphite spheres from waste graphite fines

Science.gov (United States)

Pappano, Peter J [Oak Ridge, TN; Rogers, Michael R [Clinton, TN

2012-05-08

A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

Mechanism analysis of improved DLC films friction behaviors with liquid sulfidation treatment

International Nuclear Information System (INIS)

Zeng Qunfeng; Yu Fei; Dong Guangneng; Mao Junhong

2012-01-01

Highlights: ► Liquid sulfidation is applied to treat DLC films. ► Sulfur atoms are chemically bonded and the graphitization presented in the treated films. ► The treated films exhibited much lower coefficient of friction than the untreated films under dry friction condition. ► The sulfidation mechanisms are supposed as surface chemical reaction and surface diffusion. ► The presence of sulfur-containing materials and graphitization are beneficial to improve anti-friction behaviors of the treated films. - Abstract: Diamond like carbon (DLC) films were treated by liquid sulfidation to improve their friction behaviors. Friction behaviors of DLC films were experimentally evaluated in ambient air under dry friction using GCr15 steel ball sliding over DLC-coated steel flat in a ball-on-disk tribometer system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were applied to identify the chemical composition and structure of DLC films. It was found that the content of sp 2 carbon bond increased and G peak shifted to high wave number after sulfidation treatment. The measurement results showed that sulfur atoms were chemically bonded and the graphitization occurred in the treated DLC films. It was indicated that the treated DLC films exhibited much better friction behaviors than the untreated films, especially for DLC films deposited with high nitrogen ratio. In this paper, we proposed the possible sulfidation mechanism of sulfurized DLC films. Sulfidation mechanism is postulated that thiourea reacted with oxygen to form sulfur-containing organic compounds which included CSSC, CSOH and (NH 2 )NH=CSO 2 H and surface diffusion during sulfidation treatment. The anti-friction behaviors of the treated DLC films can be attributed to the production of the compounds containing sulfur on the DLC film surface, the reduce of oxygen content and the presence of graphitization of DLC films.

Degradation of Carbon Fiber Reinforced Polymer and Graphite by Laser Heating

Science.gov (United States)

2016-08-01

Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Nicholas C. Herr, BS, MS Captain...ensuring good thermal contact between the sample and its holder (by using sample powders, pellets, or thin films ). The sample temperature is also...carbon nanotube and carbon-containing thin- film manufacturing [82–84] as well as cleaning graphite surfaces in experimental fusion reactors [83

Simultaneous determination of glucose turnover, alanine turnover, and gluconeogenesis in human using a double stable-isotope-labeled tracer infusion and gas chromatography-mass spectrometry analysis

International Nuclear Information System (INIS)

Martineau, A.; Lecavalier, L.; Falardeau, P.; Chiasson, J.L.

1985-01-01

We have developed and validated a new method to measure simultaneously glucose turnover, alanine turnover, and gluconeogenesis in human, in steady and non-steady states, using a double stable-isotope-labeled tracer infusion and GC-MS analysis. The method is based on the concomitant infusion and dilution of D-[2,3,4,6,6-2H5]glucose and L-[1,2,3-13C3]alanine. The choice of the tracers was done on the basis of a minimal overlap between the ions of interest and those arising from natural isotopic abundances. Alanine was chosen as the gluconeogenic substrate because it is the major gluconeogenic amino acid extracted by the liver and, with lactate, constitutes the bulk of the gluconeogenic precursors. The method was validated by comparing the results obtained during simultaneous infusion of trace amounts of both stable isotope labeled compounds with the radioactive tracers (D-[3-3H]glucose and L-[1,2,3-14C3]alanine) in a normal and a diabetic subject; the radiolabeled tracers were used as the accepted reference procedure. A slight overestimation of glucose turnover (7.3 versus 6.8 in normal and 10.8 versus 9.2 mumol/kg min in diabetic subject) was noticed when the stable isotope-labeled tracers were used. For the basal turnover rate of alanine, similar values were obtained with both methods (6.2 mumol/kg min). For gluconeogenesis, higher values were observed in the basal state with the stable isotopes (0.42 versus 0.21 mumol/kg min); however, these differences disappeared in the postprandial period after the ingestion of a mixed meal. Despite those minor differences, the overall correlation with the reference method was excellent for glucose turnover (r = 0.87) and gluconeogenesis (r = 0.86)

Synthesis of deuterium-labeled prochlorperazine.

Science.gov (United States)

Hawes, E M; Gurnsey, T S; Shetty, H U; Midha, K K

1983-06-01

The propylpiperazine side chain of prochlorperazine was labeled with two, four, or six deuterium atoms by lithium aluminum deuteride reduction of the appropriate amide. The isotopic purity of the products after correcting for chlorine isotopes was greater than 95.7%.

Electronic structures of ultra-thin silicon carbides deposited on graphite

International Nuclear Information System (INIS)

Baba, Y.; Sekiguchi, T.; Shimoyama, I.; Nath, Krishna G.

2004-01-01

Electronic structures of ultra-thin silicon carbide films have been investigated by X-ray photoelectron spectroscopy (XPS) and Si K-edge X-ray absorption near edge structure (XANES) using linearly polarized synchrotron soft X-rays. Silicon carbide films were deposited on the surface of highly oriented pyrolytic graphite (HOPG) by ion beam deposition method. Tetramethylsilane (Si(CH 3 ) 4 ) was used as a discharge gas. The XPS and XANES features for the thick layers were similar to those for the bulk SiC. For sub-monolayered films, the Si 1s binding energy in XPS was higher by 2.5 eV than that for bulk SiC. This suggests the existence of low-dimensional SiC x where the silicon atoms are more positively charged than those in bulk SiC. After annealing the sub-monolayered film at 850 deg. C, a new peak appeared around 1840 eV in the XANES spectrum. The energy of this new peak was lower than those for any other silicon compounds. The low-energy feature of the XANES peak suggests the existence of π*-like orbitals around the silicon atom. On the basis of the polarization dependencies of the XANES spectra, it was revealed that the direction of the π*-like orbitals are nearly perpendicular to the surface. We conclude that sub-monolayered SiC x film exhibits flat-lying structure of which configuration is similar to a single sheet of graphite

Structural disorder of graphite and implications for graphite thermometry

Science.gov (United States)

Kirilova, Martina; Toy, Virginia; Rooney, Jeremy S.; Giorgetti, Carolina; Gordon, Keith C.; Collettini, Cristiano; Takeshita, Toru

2018-02-01

Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25 megapascal (MPa) and aseismic velocities of 1, 10 and 100 µm s-1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings.

Asymptomatic Intracorneal Graphite Deposits following Graphite Pencil Injury

OpenAIRE

Philip, Swetha Sara; John, Deepa; John, Sheeja Susan

2012-01-01

Reports of graphite pencil lead injuries to the eye are rare. Although graphite is considered to remain inert in the eye, it has been known to cause severe inflammation and damage to ocular structures. We report a case of a 12-year-old girl with intracorneal graphite foreign bodies following a graphite pencil injury.

Combining position-specific 13C labeling with compound-specific isotope analysis: first steps towards soil fluxomics

Science.gov (United States)

Dippold, Michaela; Kuzyakov, Yakov

2015-04-01

Understanding the soil organic matter (SOM) dynamics is one of the most important challenges in soil science. Transformation of low molecular weight organic substances (LMWOS) is a key step in biogeochemical cycles because 1) all high molecular substances pass this stage during their decomposition and 2) only LMWOS will be taken up by microorganisms. Previous studies on LMWOS were focused on determining net fluxes through the LMWOS pool, but they rarely identified transformations. As LMWOS are the preferred C and energy source for microorganisms, the transformations of LMWOS are dominated by biochemical pathways of the soil microorganisms. Thus, understanding fluxes and transformations in soils requires a detailed knowledge on the biochemical pathways and its controlling factors. Tracing C fate in soil by isotopes became on of the most applied and promising biogeochemistry tools. Up to now, studies on LMWOS were nearly exclusively based on uniformly labeled organic substances i.e. all C atoms in the molecules were labeled with 13C or 14C. However, this classical approach did not allow the differentiation between use of intact initial substances in any process, or whether they were transformed to metabolites. The novel tool of position-specific labeling enables to trace molecule atoms separately and thus to determine the cleavage of molecules - a prerequisite for metabolic tracing. Position-specific labeling of LMWOS and quantification of 13CO2 and 13C in bulk soil enabled following the basic metabolic pathways of soil microorganisms. However, only the combination of position-specific 13C labeling with compound-specific isotope analysis of microbial biomarkers and metabolites allowed 1) tracing specific anabolic pathways in diverse microbial communities in soils and 2) identification of specific pathways of individual functional microbial groups. So, these are the prerequisites for soil fluxomics. Our studies combining position-specific labeled glucose with amino

Modelling of pulsed electron beam induced graphite ablation: Sublimation versus melting

Science.gov (United States)

Ali, Muddassir; Henda, Redhouane

2017-12-01

Pulsed electron beam ablation (PEBA) has recently emerged as a very promising technique for the deposition of thin films with superior properties. Interaction of the pulsed electron beam with the target material is a complex process, which consists of heating, phase transition, and erosion of a small portion from the target surface. Ablation can be significantly affected by the nature of thermal phenomena taking place at the target surface, with subsequent bearing on the properties, stoichiometry and structure of deposited thin films. A two stage, one-dimensional heat conduction model is presented to describe two different thermal phenomena accounting for interaction of a graphite target with a polyenergetic electron beam. In the first instance, the thermal phenomena are comprised of heating, melting and vaporization of the target surface, while in the second instance the thermal phenomena are described in terms of heating and sublimation of the graphite surface. In this work, the electron beam delivers intense electron pulses of ∼100 ns with energies up to 16 keV and an electric current of ∼400 A to a graphite target. The temperature distribution, surface recession velocity, ablated mass per unit area, and ablation depth for the graphite target are numerically simulated by the finite element method for each case. Based on calculation findings and available experimental data, ablation appears to occur mainly in the regime of melting and vaporization from the surface.

Stable isotopes

International Nuclear Information System (INIS)

Brazier, J.L.; Guinamant, J.L.

1995-01-01

According to the progress which has been realised in the technology of separating and measuring isotopes, the stable isotopes are used as preferable 'labelling elements' for big number of applications. The isotopic composition of natural products shows significant variations as a result of different reasons like the climate, the seasons, or their geographic origins. So, it was proved that the same product has a different isotopic composition of alimentary and agriculture products. It is also important in detecting the pharmacological and medical chemicals. This review article deals with the technology, like chromatography and spectrophotometry, adapted to this aim, and some important applications. 17 refs. 6 figs

Stable isotope labelling with amino acids in cell culture for human embryonic stem cell proteomic analysis

DEFF Research Database (Denmark)

Harkness, Linda; Prokhorova, Tatyana A; Kassem, Moustapha

2012-01-01

The identification and quantitative measurements of proteins in human embryonic stem cells (hESC) is a fast growing interdisciplinary area with an enormous impact on understanding the biology of hESC and the mechanism controlling self-renewal and differentiation. Using a quantitative mass...... spectroscopic method of stable isotope labelling with amino acids during cell culture (SILAC), we are able to analyse differential expression of proteins from different cellular compartments and to identify intracellular signalling pathways involved in self-renewal and differentiation. In this chapter, we...

Isotopic Abundance and Chemical Purity Analysis of Stable Isotope Deuterium Labeled Sudan I

Directory of Open Access Journals (Sweden)

CAI Yin-ping;LEI Wen;ZHENG Bo;DU Xiao-ning

2014-02-01

Full Text Available It is important that to analysis of the isotopic abundance and chemical purity of Sudan I-D5, which is the internal standard of isotope dilution mass spectrometry. The isotopic abundance of Sudan I-D5 is detected by “mass cluster” classification method and LC-MS. The repeatability and reproducibility experiments were carried out by using different mass spectrometers and different operators. The RSD was less than 0.1%, so the repeatability and reproducibility were satisfactory. The accuracy and precision of the isotopic abundance analysis method was good with the results of F test and t test. The high performance liquid chromatography (HPLC had been used for detecting the chemical purity of Sudan I-D5 as external standard method.

Bacterial expression and one-step purification of an isotope-labeled heterotrimeric G-protein α-subunit

International Nuclear Information System (INIS)

Abdulaev, Najmoutin G.; Zhang Cheng; Dinh, Andy; Ngo, Tony; Bryan, Philip N.; Brabazon, Danielle M.; Marino, John P.; Ridge, Kevin D.

2005-01-01

Heterologous expression systems are often employed to generate sufficient quantities of isotope-labeled proteins for high-resolution NMR studies. Recently, the interaction between the prodomain region of subtilisin and an active, mutant form of the mature enzyme has been exploited to develop a cleavable affinity tag fusion system for one-step generation and purification of full-length soluble proteins obtained by inducible prokaryotic expression. As a first step towards applying high-resolution NMR methods to study heterotrimeric G-protein α-subunit (G α ) conformation and dynamics, the utility of this subtilisin prodomain fusion system for expressing and purifying an isotope-labeled G α chimera (∼40 kDa polypeptide) has been tested. The results show that a prodomain fused G α chimera can be expressed to levels approaching 6-8 mg/l in minimal media and that the processed, mature protein exhibits properties similar to those of G α isolated from natural sources. To assay for the functional integrity of the purified G α chimera at NMR concentrations and probe for changes in the structure and dynamics of G α that result from activation, 15 N-HSQC spectra of the GDP/Mg 2+ bound form of G α obtained in the absence and presence of aluminum fluoride, a well known activator of the GDP bound state, have been acquired. Comparisons of the 15 N-HSQC spectra reveals a number of changes in chemical shifts of the 1 HN, 15 N crosspeaks that are discussed with respect to expected changes in the protein conformation associated with G α activation

Preparation of radiopharmaceuticals labelled with bromine positron emitting isotopes for the study of dopaminergic receptors of the central nervous system using positron emission tomography

International Nuclear Information System (INIS)

Loc'h, C.

1988-04-01

The in vivo study of dopaminergic receptors of the central nervous system using positron emission tomography requires the preparation of radiopharmaceuticals labelled with β + emitting isotopes. The chemical and pharmacological properties of these ligands are evaluated. Cyclotron produced 75 and 76 bromine β + emitting isotopes are incorporated into dopaminergic ligands by electrophilic substitution using peracetic acid in a no-carrier added form. Purity, lipophilicity and specific activity are analyzed. Pharmacological criteria (specificity, saturability, displacement, localization) required for ligand-receptor binding studies are evaluated in vitro on striatal membranes and in vivo in the rat. Positron emission tomographic studies show that the study of dopaminergic D2 receptors is possible using 75 and 76 bromine labelled bromospiperone and bromolisuride. These ligands are used in physiological and pharmacological studies of the central nervous system [fr

Microwave plasma chemical synthesis of nanocrystalline carbon film structures and study their properties

Science.gov (United States)

Bushuev, N.; Yafarov, R.; Timoshenkov, V.; Orlov, S.; Starykh, D.

2015-08-01

The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm2 was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

Structural disorder of graphite and implications for graphite thermometry

Directory of Open Access Journals (Sweden)

M. Kirilova

2018-02-01

Full Text Available Graphitization, or the progressive maturation of carbonaceous material, is considered an irreversible process. Thus, the degree of graphite crystallinity, or its structural order, has been calibrated as an indicator of the peak metamorphic temperatures experienced by the host rocks. However, discrepancies between temperatures indicated by graphite crystallinity versus other thermometers have been documented in deformed rocks. To examine the possibility of mechanical modifications of graphite structure and the potential impacts on graphite thermometry, we performed laboratory deformation experiments. We sheared highly crystalline graphite powder at normal stresses of 5 and 25  megapascal (MPa and aseismic velocities of 1, 10 and 100 µm s−1. The degree of structural order both in the starting and resulting materials was analyzed by Raman microspectroscopy. Our results demonstrate structural disorder of graphite, manifested as changes in the Raman spectra. Microstructural observations show that brittle processes caused the documented mechanical modifications of the aggregate graphite crystallinity. We conclude that the calibrated graphite thermometer is ambiguous in active tectonic settings.

Classification-based quantitative analysis of stable isotope labeling by amino acids in cell culture (SILAC) data.

Science.gov (United States)

Kim, Seongho; Carruthers, Nicholas; Lee, Joohyoung; Chinni, Sreenivasa; Stemmer, Paul

2016-12-01

Stable isotope labeling by amino acids in cell culture (SILAC) is a practical and powerful approach for quantitative proteomic analysis. A key advantage of SILAC is the ability to simultaneously detect the isotopically labeled peptides in a single instrument run and so guarantee relative quantitation for a large number of peptides without introducing any variation caused by separate experiment. However, there are a few approaches available to assessing protein ratios and none of the existing algorithms pays considerable attention to the proteins having only one peptide hit. We introduce new quantitative approaches to dealing with SILAC protein-level summary using classification-based methodologies, such as Gaussian mixture models with EM algorithms and its Bayesian approach as well as K-means clustering. In addition, a new approach is developed using Gaussian mixture model and a stochastic, metaheuristic global optimization algorithm, particle swarm optimization (PSO), to avoid either a premature convergence or being stuck in a local optimum. Our simulation studies show that the newly developed PSO-based method performs the best among others in terms of F1 score and the proposed methods further demonstrate the ability of detecting potential markers through real SILAC experimental data. No matter how many peptide hits the protein has, the developed approach can be applicable, rescuing many proteins doomed to removal. Furthermore, no additional correction for multiple comparisons is necessary for the developed methods, enabling direct interpretation of the analysis outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Analytical performance of reciprocal isotope labeling of proteome digests for quantitative proteomics and its application for comparative studies of aerobic and anaerobic Escherichia coli proteomes

International Nuclear Information System (INIS)

Lo, Andy; Weiner, Joel H.; Li, Liang

2013-01-01

Graphical abstract: -- Highlights: •Investigating a strategy of reciprocal isotope labeling of comparative samples. •Filtering out incorrect peptide identification or quantification values. •Analyzing the proteome changes of E. coli cells grown aerobically or anaerobically. •Presenting guidelines for reciprocal labeling experimental design. -- Abstract: Due to limited sample amounts, instrument time considerations, and reagent costs, only a small number of replicate experiments are typically performed for quantitative proteome analyses. Generation of reproducible data that can be readily assessed for consistency within a small number of datasets is critical for accurate quantification. We report our investigation of a strategy using reciprocal isotope labeling of two comparative samples as a tool for determining proteome changes. Reciprocal labeling was evaluated to determine the internal consistency of quantified proteome changes from Escherichia coli grown under aerobic and anaerobic conditions. Qualitatively, the peptide overlap between replicate analyses of the same sample and reverse labeled samples were found to be within 8%. Quantitatively, reciprocal analyses showed only a slight increase in average overall inconsistency when compared with replicate analyses (1.29 vs. 1.24-fold difference). Most importantly, reverse labeling was successfully used to identify spurious values resulting from incorrect peptide identifications and poor peak fitting. After removal of 5% of the peptide data with low reproducibility, a total of 275 differentially expressed proteins (>1.50-fold difference) were consistently identified and were then subjected to bioinformatics analysis. General considerations and guidelines for reciprocal labeling experimental design and biological significance of obtained results are discussed

Roll-to-Roll Laser-Printed Graphene-Graphitic Carbon Electrodes for High-Performance Supercapacitors.

Science.gov (United States)

Kang, Sangmin; Lim, Kyungmi; Park, Hyeokjun; Park, Jong Bo; Park, Seong Chae; Cho, Sung-Pyo; Kang, Kisuk; Hong, Byung Hee

2018-01-10

Carbon electrodes including graphene and thin graphite films have been utilized for various energy and sensor applications, where the patterning of electrodes is essentially included. Laser scribing in a DVD writer and inkjet printing were used to pattern the graphene-like materials, but the size and speed of fabrication has been limited for practical applications. In this work, we devise a simple strategy to use conventional laser-printer toner materials as precursors for graphitic carbon electrodes. The toner was laser-printed on metal foils, followed by thermal annealing in hydrogen environment, finally resulting in the patterned thin graphitic carbon or graphene electrodes for supercapacitors. The electrochemical cells made of the graphene-graphitic carbon electrodes show remarkably higher energy and power performance compared to conventional supercapacitors. Furthermore, considering the simplicity and scalability of roll-to-roll (R2R) electrode patterning processes, the proposed method would enable cheaper and larger-scale synthesis and patterning of graphene-graphitic carbon electrodes for various energy applications in the future.

Study of reactions of isotopic exchange of trans-zeatin with tritium

International Nuclear Information System (INIS)

Sidorov, G.V.; Myasoedov, N.F.

2006-01-01

Reactions of isotopic exchange of trans-zeatin with high-radioactive tritium water, with gaseous tritium in solution and solid-phase catalytic hydrogenation are studied to prepare trans-zeatin and dihydrozeatin labelled with tritium. It is shown that reaction of isotopic exchange of trans-zeatin with gaseous tritium both in solutions and without solvents at 160 Deg C and above leads to practically total hydrogenation of initial compound with formation of dihydrozeatin labelled with tritium. Isotopic exchange with tritium water permits to prepare zeatin labelled with tritium with 67 % yield and specific radioactivity 0.68 PBq/mol. It is determined that in the case of solid-phase isotopic exchange within 150-155 Deg C temperature interval both dihydrozeatin and trans-zeatin labelled with tritium are formed [ru

Failure to label baboon milk intrinsically with iron

International Nuclear Information System (INIS)

Figueroa-Colon, R.; Elwell, J.H.; Jackson, E.; Osborne, J.W.; Fomon, S.J.

1989-01-01

The widely held belief that 50% of the iron in human milk is absorbed is based on studies that have used an extrinsic radioactive iron tag. To determine the validity of an extrinsic tag, it is necessary to label the milk intrinsically with one isotope and to compare absorption of this isotope with absorption of another isotope added as the extrinsic tag. We chose the baboon as a model and infused 59Fe intravenously. In each of three attempts we failed to label the milk intrinsically

Structures of sub-monolayered silicon carbide films

International Nuclear Information System (INIS)

Baba, Y.; Sekiguchi, T.; Shimoyama, I.; Nath, Krishna G.

2004-01-01

The electronic and geometrical structures of silicon carbide thin films are presented. The films were deposited on graphite by ion-beam deposition using tetramethylsilane (TMS) as an ion source. In the Si K-edge near-edge X-ray absorption fine structure (NEXAFS) spectra for sub-monolayered film, sharp peaks due to the resonance from Si 1s to π*-like orbitals were observed, suggesting the existence of Si=C double bonds. On the basis of the polarization dependencies of the Si 1s → π* peak intensities, it is elucidated that the direction of the π*-like orbitals is just perpendicular to the surface. We conclude that the sub-monolayered SiC x film has a flat-lying hexagonal structure of which configuration is analogous to the single sheet of graphite

Annealing effect on the microstructure modification and tribological properties of amorphous carbon nitride films

Science.gov (United States)

Wang, Zhou; Wang, Chengbing; Wang, Qi; Zhang, Junyan

2008-10-01

The influences of thermal annealing on the microstructural and tribological properties of amorphous carbon nitride films were investigated. X-ray photoelectron spectroscopy, Raman spectroscopy, and Fourier transform infrared spectrometer were utilized to characterize bond configuration and chemical state of the films. The results indicated that at low annealing temperatures (200 and 300 °C), the volatile species and surface contamination are easily dissociated without obvious bulk modification; while at high annealing temperatures (400 and 500 °C), the microstructure of carbon nitride films changed and favored a graphitization process, which indicated the growth of more graphitic film structures. The faint Raman signal of C≡N decreased with annealing temperature (TA) and completely disappeared at TA of 500 °C, indicating that nitrile bonds were thermal unstable under high temperature. Surprisingly, the tribological properties of the films showed a remarkably decreasing in friction coefficient as the TA increased; it is attributed to the graphitization of carbon nitride films during thermal annealing, which favored transfer film formation between the carbon nitride films and counterface materials. The transfer films benefit the decrease in coefficient of friction.

Graphitic encapsulation of MgO and Fe3C nanoparticles in the reaction of iron pentacarbonyl with magnesium

International Nuclear Information System (INIS)

Dyjak, Sławomir; Cudziło, Stanisław; Polański, Marek; Budner, Bogusław; Bystrzycki, Jerzy

2013-01-01

A simple method to produce highly ordered carbon nanostructures by combustion synthesis is presented. Graphite-encapsulated magnesium oxide, iron carbide nanoparticles and carbon nanobelts were synthesized by the one-step reduction of iron pentacarbonyl with magnesium. High-resolution transmission electron microscopy analysis of the products revealed nanocrystalline MgO and Fe 3 C particles surrounded by a well-crystallized, tight graphite film. The possible formation mechanism is presented and discussed. - Highlights: • We present a simple method to produce highly ordered carbon nanostructures by combustion synthesis. • The cubic MgO particles are completely coated by tight graphitic shells. • The mechanism of formation a distant carbon film on MgO surface has been discussed. • The presented method can be applied to synthesis of other core-shell structures

A cost-effective approach to produce 15N-labelled amino acids employing Chlamydomonas reinhardtii CC503.

Science.gov (United States)

Nicolás Carcelén, Jesús; Marchante-Gayón, Juan Manuel; González, Pablo Rodríguez; Valledor, Luis; Cañal, María Jesús; Alonso, José Ignacio García

2017-08-18

The use of enriched stable isotopes is of outstanding importance in chemical metrology as it allows the application of isotope dilution mass spectrometry (IDMS). Primary methods based on IDMS ensure the quality of the analytical measurements and traceability of the results to the international system of units. However, the synthesis of isotopically labelled molecules from enriched stable isotopes is an expensive and a difficult task. Either chemical and biochemical methods to produce labelled molecules have been proposed, but so far, few cost-effective methods have been described. The aim of this study was to use the microalgae Chlamydomonas reinhardtii to produce, at laboratory scale, 15 N-labelled amino acids with a high isotopic enrichment. To do that, a culture media containing 15 NH 4 Cl was used. No kinetic isotope effect (KIE) was observed. The labelled proteins biosynthesized by the microorganism were extracted from the biomass and the 15 N-labelled amino acids were obtained after a protein hydrolysis with HCl. The use of the wall deficient strain CC503 cw92 mt+ is fit for purpose, as it only assimilates ammonia as nitrogen source, avoiding isotope contamination with nitrogen from the atmosphere or the reagents used in the culture medium, and enhancing the protein extraction efficiency compared to cell-walled wild type Chlamydomonas. The isotopic enrichment of the labelled amino acids was calculated from their isotopic composition measured by gas chromatography mass spectrometry (GC-MS). The average isotopic enrichment for the 16 amino acids characterized was 99.56 ± 0.05% and the concentration of the amino acids in the hydrolysate ranged from 18 to 90 µg/mL. Previously reported biochemical methods to produce isotopically labelled proteins have been applied in the fields of proteomics and fluxomics. For these approaches, low amounts of products are required and the isotopic enrichment of the molecules has never been properly determined. So far, only 13

A Breast Cell Atlas: Organelle analysis of the MDA-MB-231 cell line by density-gradient fractionation using isotopic marking and label-free analysis

Directory of Open Access Journals (Sweden)

Marianne Sandin

2015-09-01

Full Text Available Protein translocation between organelles in the cell is an important process that regulates many cellular functions. However, organelles can rarely be isolated to purity so several methods have been developed to analyse the fractions obtained by density gradient centrifugation. We present an analysis of the distribution of proteins amongst organelles in the human breast cell line, MDA-MB-231 using two approaches: an isotopic labelling and a label-free approach.

Uniform isotope labeling of a eukaryotic seven-transmembrane helical protein in yeast enables high-resolution solid-state NMR studies in the lipid environment

International Nuclear Information System (INIS)

Fan Ying; Shi Lichi; Ladizhansky, Vladimir; Brown, Leonid S.

2011-01-01

Overexpression of isotope-labeled multi-spanning eukaryotic membrane proteins for structural NMR studies is often challenging. On the one hand, difficulties with achieving proper folding, membrane insertion, and native-like post-translational modifications frequently disqualify bacterial expression systems. On the other hand, eukaryotic cell cultures can be prohibitively expensive. One of the viable alternatives, successfully used for producing proteins for solution NMR studies, is yeast expression systems, particularly Pichia pastoris. We report on successful implementation and optimization of isotope labeling protocols, previously used for soluble secreted proteins, to produce homogeneous samples of a eukaryotic seven-transmembrane helical protein, rhodopsin from Leptosphaeria maculans. Even in shake-flask cultures, yields exceeded 5 mg of purified uniformly 13 C, 15 N-labeled protein per liter of culture. The protein was stable (at least several weeks at 5°C) and functionally active upon reconstitution into lipid membranes at high protein-to-lipid ratio required for solid-state NMR. The samples gave high-resolution 13 C and 15 N solid-state magic angle spinning NMR spectra, amenable to a detailed structural analysis. We believe that similar protocols can be adopted for challenging mammalian targets, which often resist characterization by other structural methods.

The uncertain future for nuclear graphite disposal: Crisis or opportunity?

International Nuclear Information System (INIS)

Wickham, A.J.; Neighbour, G.B.; Dubourg, M.

2001-01-01

Over the last twenty years, numerous proposals have been made for the long-term treatment of radioactive graphite waste. These plans have ranged from sea dumping through incineration to land-based disposal, sometimes preceded by a variable period of 'safe-storage' within the original reactor containment, to allow for the decay of shorter-lived isotopes ahead of dismantling. A number of novel chemical or physical pre-treatments of the graphite, with the objective of facilitating its subsequent disposal or improving the environmental consequences of the chosen disposal route, have also been suggested. There are patents issued on systems for transmutation of long-lived isotopes to reduce the radiological consequences of disposal of intact graphite, and for separation of certain isotopes such as carbon-14 from the matrix in an incineration process. Although these far-reaching proposals are not apparently cost-effective, scope for cost-recovery does exist, i.e., in terms of disposal of the separated carbon-14 in cements used for immobilisation of other radioactive solid waste materials. More recently, political and environmental factors have further complicated the issue. Nuclear regulators are challenging the proposed length of 'safe-storage' schemes on the basis that essential knowledge on the reactor materials may be lost in the interim. International agreements such as OSPAR have effectively eliminated the possibility for disposal at sea, whilst public opinion is strongly expressed against any expansion of existing land-based disposal sites or the creation of new ones. As a particular example, the United Kingdom authorities recently denied to the official body charged with the development of a deep repository the necessary planning consents to develop an exploratory rock-structure laboratory on the most favoured site. The current drive towards minimising or eliminating any radioactivity release to the environment has the unintended consequence of causing the waste

Interactions of the spin-labeled chloroethylnitrosourea SLCNUgly with electrode-supported lipid films

International Nuclear Information System (INIS)

Tacheva, Bilyana; Georgieva, Radostina; Karabaliev, Miroslav

2016-01-01

The spin-labeled chloroethylnitrosourea containig glycine SLCNUgly is an analogue of the clinically used nitrosourea drug lomustine (1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, CCNU), showing promising properties and features in vitro as well as in vivo. In this work the interaction of SLCNUgly with a lipid model membrane is investigated. The presented results indicate penetration of the drug in the membranes without causing defects of the lipid structure and reveal the potential of both SLCNUgly and electrode-supported lipid films as models for investigating nitrosourea drugs-membrane interactions.

Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach.

Science.gov (United States)

Huang, Zhi-Yong; Xie, Hong; Cao, Ying-Lan; Cai, Chao; Zhang, Zhi

2014-02-15

The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of (206)Pb, the contamination of exogenous Pb(2+) ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60-85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60-66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine

International Nuclear Information System (INIS)

Shahrokhian, Saeed; Ghalkhani, Masoumeh

2010-01-01

A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental variables, such as the deposited amount of modifier suspension, the pH of the supporting electrolyte, the accumulation potential and time were investigated. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2-100 μM with a detection limit of 65 nM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode can be successfully applied to the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations.

Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine

Energy Technology Data Exchange (ETDEWEB)

Shahrokhian, Saeed, E-mail: shahrokhian@sharif.ed [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Ghalkhani, Masoumeh [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of)

2010-04-15

A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental variables, such as the deposited amount of modifier suspension, the pH of the supporting electrolyte, the accumulation potential and time were investigated. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2-100 muM with a detection limit of 65 nM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode can be successfully applied to the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations.

Derivation of a radionuclide inventory for irradiated graphite-chlorine-36 inventory determination

International Nuclear Information System (INIS)

Brown, F.J.; Palmer, J.D.; Wood, P.

2001-01-01

The irradiation of materials in nuclear reactors results in neutron activation of component elements. Irradiated graphite wastes arise from their use in UK gas-cooled research and commercial reactor cores, and in fuel element components, where the graphite has acted as the neutron moderator. During irradiation the residual chlorine, which was used to purify the graphite during manufacture, is activated to chlorine-36. This isotope is long-lived and poorly retarded by geological barriers, and may therefore be a key radionuclide with respect to post-closure disposal facilities performance. United Kingdom Nirex Limited, currently responsible for the development of a disposal route for intermediate-level radioactive wastes in the UK, carried out a major research programme to support an overall assessment of the chlorine-36 activity of all wastes including graphite reactor components. The various UK gas cooled reactors reactors have used a range of graphite components made from diverse graphite types; this has necessitated a systematic programme to cover the wide range of graphite and production processes. The programme consisted of: precursor measurements - on the surface and/or bulk of representative samples of relevant materials, using specially developed methods; transfer studies - to quantify the potential for transfer of Cl-36 into and between waste streams during irradiation of graphite; theoretical assessments - to support the calculational methodology; actual measurements - to confirm the modelling. For graphite, a total of 458 measurements on samples from 57 batches were performed, to provide a detailed understanding of the composition of nuclear graphite. The work has resulted in the generation of probability density functions (PDF) for the mean chlorine concentration of three classes of graphite: fuel element graphite; Magnox moderator and reflector graphite and AGR reflector graphite; AGR moderator graphite. Transfer studies have shown that a significant

Modern spectrometric methods for the analysis of labelled compounds

International Nuclear Information System (INIS)

Kaspersen, F.M.; Funke, C.W.; Wagenaars, G.N.; Jacobs, P.L.

1988-01-01

A proper analysis of chemical compounds should give information about the chemical identity (not only the structure but also enantiomeric form), the chemical purity and chemical composition (e.g. giving information about counter-ions, solvents of crystallization). For labelled compounds information is also needed about isotopic purity (defined as the % of isotope present in the compound), the position/distribution of the isotope in the molecule and degree of labelling/specific activity. In the past ten years the possibilities for spectrometric analyses of labelled compounds have increased enormously and this chapter will give an overview of these methods with the exception of (radio)chromatography that will be dealt with in another chapter. (author)

Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth

Science.gov (United States)

2017-01-01

In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed 15N-enriched algae (0.4–5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies. PMID:28405367

Reductive methods for isotopic labeling of antibiotics

International Nuclear Information System (INIS)

Champney, W.S.

1989-01-01

Methods for the reductive methylation of the amino groups of eight different antibiotics using 3 HCOH or H 14 COH are presented. The reductive labeling of an additional seven antibiotics by NaB 3 H 4 is also described. The specific activity of the methyl-labeled drugs was determined by a phosphocellulose paper binding assay. Two quantitative assays for these compounds based on the reactivity of the antibiotic amino groups with fluorescamine and of the aldehyde and ketone groups with 2,4-dinitrophenylhydrazine are also presented. Data on the cellular uptake and ribosome binding of these labeled compounds are also presented

Bacterial expression and one-step purification of an isotope-labeled heterotrimeric G-protein {alpha}-subunit

Energy Technology Data Exchange (ETDEWEB)

Abdulaev, Najmoutin G. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States); Zhang Cheng; Dinh, Andy [University of Texas Health Science Center, Center for Membrane Biology, Department of Biochemistry and Molecular Biology (United States); Ngo, Tony; Bryan, Philip N. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States); Brabazon, Danielle M. [Loyola College in Maryland, Department of Chemistry (United States); Marino, John P. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States)], E-mail: marino@carb.nist.gov; Ridge, Kevin D. [University of Texas Health Science Center, Center for Membrane Biology, Department of Biochemistry and Molecular Biology (United States)

2005-05-15

Heterologous expression systems are often employed to generate sufficient quantities of isotope-labeled proteins for high-resolution NMR studies. Recently, the interaction between the prodomain region of subtilisin and an active, mutant form of the mature enzyme has been exploited to develop a cleavable affinity tag fusion system for one-step generation and purification of full-length soluble proteins obtained by inducible prokaryotic expression. As a first step towards applying high-resolution NMR methods to study heterotrimeric G-protein {alpha}-subunit (G{sub {alpha}}) conformation and dynamics, the utility of this subtilisin prodomain fusion system for expressing and purifying an isotope-labeled G{sub {alpha}} chimera ({approx}40 kDa polypeptide) has been tested. The results show that a prodomain fused G{sub {alpha}} chimera can be expressed to levels approaching 6-8 mg/l in minimal media and that the processed, mature protein exhibits properties similar to those of G{sub {alpha}} isolated from natural sources. To assay for the functional integrity of the purified G{sub {alpha}} chimera at NMR concentrations and probe for changes in the structure and dynamics of G{sub {alpha}} that result from activation, {sup 15}N-HSQC spectra of the GDP/Mg{sup 2+} bound form of G{sub {alpha}} obtained in the absence and presence of aluminum fluoride, a well known activator of the GDP bound state, have been acquired. Comparisons of the {sup 15}N-HSQC spectra reveals a number of changes in chemical shifts of the {sup 1}HN, {sup 15}N crosspeaks that are discussed with respect to expected changes in the protein conformation associated with G{sub {alpha}} activation.

Sequence-specific label-free nucleic acid biosensor for the detection of the hepatitis C virus genotype 1a using a disposable pencil graphite electrode.

Science.gov (United States)

Donmez, Soner; Arslan, Fatma; Arslan, Halit

2016-05-01

In this paper, we demonstrate a simple, sensitive, inexpensive, disposable and label-free electrochemical nucleic acid biosensor for the detection of the hepatitis C virus genotype 1a (HCV1a). The nucleic acid biosensor was designed with the amino-linked inosine-substituted 20-mer probes, which were immobilized onto a disposable pencil graphite electrode (PGE) by covalent linking. The proposed nucleic acid biosensor was linear in the range of 0.05 and 0.75 μM, exhibiting a limit of detection of 54.9 nM. The single-stranded synthetic PCR product analogs of HCV1a were also detected with satisfactory results under optimal conditions, showing the potential application of this biosensor.

Magnified fluorescence detection of silver(I) ion in aqueous solutions by using nano-graphite-DNA hybrid and DNase I.

Science.gov (United States)

Wei, Yin; Li, Bianmiao; Wang, Xu; Duan, Yixiang

2014-08-15

This paper describes a novel approach utilizing nano-graphite-DNA hybrid and DNase I for the amplified detection of silver(I) ion in aqueous solutions for the first time. Nano-graphite can effectively quench the fluorescence of dye-labeled cytosine-rich single-stranded DNA due to its strong π-π stacking interactions; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on the surface of nano-graphite and thus retains the dye fluorescence. Meanwhile, the hairpin structure can be cleaved by DNase I, and in such case Ag(+) is delivered from the complex. The released Ag(+) then binds other dye-labeled single-stranded DNA on the nano-graphite surface, and touches off another target recycling, resulting in the successive release of dye-labeled single-stranded DNA from the nano-graphite, which leads to significant amplification of the signal. The present magnification sensing system exhibits high sensitivity toward Ag(+) with a limit of detection of 0.3nM (S/N=3), which is much lower than the standard for Ag(+) in drinking water recommended by the Environmental Protection Agency (EPA). The selectivity of the sensor for Ag(+) against other biologically and environmentally related metal ions is outstanding due to the high specificity of C-Ag(+)-C formation. Moreover, the sensing system is used for the determination of Ag(+) in river water samples with satisfying results. The proposed assay is simple, cost-effective, and might open the door for the development of new assays for other metal ions or biomolecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Adhesion and friction in polymer films on solid substrates: conformal sites analysis and corresponding surface measurements.

Science.gov (United States)

An, Rong; Huang, Liangliang; Mineart, Kenneth P; Dong, Yihui; Spontak, Richard J; Gubbins, Keith E

2017-05-21

In this work, we present a statistical mechanical analysis to elucidate the molecular-level factors responsible for the static and dynamic properties of polymer films. This analysis, which we term conformal sites theory, establishes that three dimensionless parameters play important roles in determining differences from bulk behavior for thin polymer films near to surfaces: a microscopic wetting parameter, α wx , defined as the ratio of polymer-substrate interaction to polymer-polymer interaction; a dimensionless film thickness, H*; and dimensionless temperature, T*. The parameter α wx introduced here provides a more fundamental measure of wetting than previous metrics, since it is defined in terms of intermolecular forces and the atomic structure of the substrate, and so is valid at the nanoscale for gas, liquid or solid films. To test this theoretical analysis, we also report atomic force microscopy measurements of the friction coefficient (μ), adhesion force (F A ) and glass transition temperature (T g ) for thin films of two polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on two planar substrates, graphite and silica. Both the friction coefficient and the glass transition temperature are found to increase as the film thickness decreases, and this increase is more pronounced for the graphite than for the silica surface. The adhesion force is also greater for the graphite surface. The larger effects encountered for the graphite surface are attributed to the fact that the microscopic wetting parameter, α wx , is larger for graphite than for silica, indicating stronger attraction of polymer chains to the graphite surface.

Temperature-induced evolution of strain and doping in an isotopically labeled two-dimensional graphene-C-70 fullerene peapod

Czech Academy of Sciences Publication Activity Database

Verhagen, Timotheus; Valeš, Václav; Kalbáč, Martin; Vejpravová, Jana

2017-01-01

Roč. 75, May (2017), s. 140-145 ISSN 0925-9635 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : two-dimensional peapod * Raman spectroscopy * isotope labelling * topography Subject RIV: BM - Solid Matter Physics ; Magnetism; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Physical chemistry (UFCH-W) Impact factor: 2.561, year: 2016

Behavior of LASL-made graphite, ZrC, and ZrC-containing coated particles in irradiation tests HT-28 and HT-29

International Nuclear Information System (INIS)

Reiswig, R.D.; Wagner, P.; Hollabaugh, C.M.; White, R.W.; O'Rourke, J.A.; Davidson, K.V.; Schell, D.H.

1976-01-01

Three types of materials, extruded graphite, hot-pressed ZrC, and particles with ZrC coatings, were irradiated in ORNL High Fluence Isotope Reactor Irradiation tests HT-28 and HT-29. The ZrC seemed unaffected. The graphite changed in dimensions, x-ray diffraction parameters, and thermal conductivity. The four types of coated particles tested all resisted the irradiation well, except one set of particles with double-graded C-ZrC-C coats. Overall, the results were considered encouraging for use of ZrC and extruded graphite fuel matrices. 16 fig

Label-Free Aptasensor for Lysozyme Detection Using Electrochemical Impedance Spectroscopy

OpenAIRE

Dionisia Ortiz-Aguayo; Manel del Valle

2018-01-01

This research develops a label-free aptamer biosensor (aptasensor) based on graphite-epoxy composite electrodes (GECs) for the detection of lysozyme protein using Electrochemical Impedance Spectroscopy (EIS) technique. The chosen immobilization technique was based on covalent bonding using carbodiimide chemistry; for this purpose, carboxylic moieties were first generated on the graphite by electrochemical grafting. The detection was performed using [Fe(CN)6]3−/[Fe(CN)6]4− as redox probe. Afte...

Isotopic labeling affects 1,25-dihydroxyvitamin D metabolism

International Nuclear Information System (INIS)

Halloran, B.P.; Bikle, D.D.; Castro, M.E.; Gee, E.

1989-01-01

Isotope substitution can change the biochemical properties of vitamin D. To determine the effect of substituting 3H for 1H on the metabolism of 1,25(OH)2D3, we measured the metabolic clearance rate and renal metabolism of unlabeled and 3H-labeled 1,25(OH)2D3. Substitution of 3H for 1H on carbons 26 and 27 [1,25(OH)2[26,27(n)-3H]D3] or on carbons 23 and 24 [1,25(OH)2[23,24(n)-3H]D3] reduced the in vivo metabolic clearance rate of 1,25(OH)2D3 by 36% and 37%, respectively, and reduced the in vitro renal catabolism of 1,25(OH)2D3 by 11% and 54%, respectively. Substitutions of 3H for 1H on carbons 23 and 24 as opposed to carbons 26 and 27 reduced conversion of [3H]1,25(OH)2D3 to [3H]1,24,25(OH)2D3 by 25% and to putative 24-oxo-1,23,25-dihydroxyvitamin D3 by 1600%. These results indicate that substitution of 3H for 1H on carbons 26 and 27 or on carbons 23 and 24 can reduce the metabolic clearance rate and in vitro metabolism of 1,25(OH)2D3 and quantitatively alter the pattern of metabolic products produced

NMR studies of two spliced leader RNAs using isotope labeling

Energy Technology Data Exchange (ETDEWEB)

Lapham, J.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

1994-12-01

Spliced leader RNAs are a class of RNA molecules (<200 nts) involved in the trans splicing of messenger RNA found in trypanosomes, nematodes, and other lower eukaryotes. The spliced leader RNA from the trypanosome Leptomonas Collosoma exists in two alternate structural forms with similar thermal stabilities. The 54 nucleotides on the 5{prime} end of the SL molecule is structurally independent from the 3{prime} half of the RNA, and displays the two structural forms. Furthermore, the favored of the two structures was shown to contain anomalous nuclease sensitivity and thermal stability features, which suggests that there may be tertiary interactions between the splice site and other nucleotides in the 5{prime} end. Multidimensional NMR studies are underway to elucidate the structural elements present in the SL RNAs that give rise to their physical properties. Two spliced leader sequences have been studied. The first, the 54 nucleotides on the 5{prime} end of the L. Collosoma sequence, was selected because of earlier studies in our laboratory. The second sequence is the 5{prime} end of the trypanosome Crithidia Fasciculata, which was chosen because of its greater sequence homology to other SL sequences. Given the complexity of the NMR spectra for RNA molecules of this size, we have incorporated {sup 15}N/{sup 13}C-labeled nucleotides into the RNA. One of the techniques we have developed to simplify the spectra of these RNA molecules is isotope labeling of specific regions of the RNA. This has been especially helpful in assigning the secondary structure of molecules that may be able to adopt multiple conformations. Using this technique one can examine a part of the molecule without spectral interference from the unlabeled portion. We hope this approach will promote an avenue for studying the structure of larger RNAs in their native surroundings.

The evaluation of new and isotopically labeled isoindoline nitroxides and an azaphenalene nitroxide for EPR oximetry

Science.gov (United States)

Khan, Nadeem; Blinco, James P.; Bottle, Steven E.; Hosokawa, Kazuyuki; Swartz, Harold M.; Micallef, Aaron S.

2011-01-01

Isoindoline nitroxides are potentially useful probes for viable biological systems, exhibiting low cytotoxicity, moderate rates of biological reduction and favorable Electron Paramagnetic Resonance (EPR) characteristics. We have evaluated the anionic (5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl; CTMIO), cationic (5-(N,N,N-trimethylammonio)-1,1,3,3-tetramethylisoindolin-2-yloxyl iodide, QATMIO) and neutral (1,1,3,3-tetramethylisoindolin-2-yloxyl; TMIO) nitroxides and their isotopically labeled analogues (2H12- and/or 2H12-15N-labeled) as potential EPR oximetry probes. An active ester analogue of CTMIO, designed to localize intracellularly, and the azaphenalene nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalen-2-yloxyl (TMAO) were also studied. While the EPR spectra of the unlabeled nitroxides exhibit high sensitivity to O2 concentration, deuteration resulted in a loss of superhyperfine features and a subsequent reduction in O2 sensitivity. Labeling the nitroxides with 15N increased the signal intensity and this may be useful in decreasing the detection limits for in vivo measurements. The active ester nitroxide showed approximately 6% intracellular localization and low cytotoxicity. The EPR spectra of TMAO nitroxide indicated an increased rigidity in the nitroxide ring, due to dibenzo-annulation. PMID:21665499

[Solid state isotope hydrogen exchange for deuterium and tritium in human gene-engineered insulin].

Science.gov (United States)

Zolotarev, Yu A; Dadayan, A K; Kozik, V S; Gasanov, E V; Nazimov, I V; Ziganshin, R Kh; Vaskovsky, B V; Murashov, A N; Ksenofontov, A L; Haribin, O N; Nikolaev, E N; Myasoedov, N F

2014-01-01

The reaction of high temperature solid state catalytic isotope exchange in peptides and proteins under the action of catalyst-activated spillover hydrogen was studied. The reaction of human gene-engineered insulin with deuterium and tritium was conducted at 120-140° C to produce insulin samples containing 2-6 hydrogen isotope atoms. To determine the distribution of the isotope label over tritium-labeled insulin's amino acid residues, oxidation of the S-S bonds of insulin by performic acid was performed and polypeptide chains isolated; then their acid hydrolysis, amino acid analysis and liquid scintillation counts of tritium in the amino acids were conducted. The isotope label was shown to be incorporated in all amino acids of the protein, with the peptide fragment FVNQHLCGSHLVE of the insulin β-chain showing the largest incorporation. About 45% of the total protein isotope label was incorporated in His5 and His10 of this fragment. For the analysis of isotope label distribution in labeled insulin's peptide fragments, the recovery of the S-S bonds by mercaptoethanol, the enzymatic hydrolysis by glutamyl endopeptidase from Bacillus intermedius and HPLC division of the resulting peptides were carried out. Attribution of the peptide fragments formed due to hydrolysis at the Glu-X bond in the β-chain was accomplished by mass spectrometry. Mass spectrometry analysis data of the deuterium-labeled insulin samples' isotopomeric composition showed that the studied solid state isotope exchange reaction equally involved all the protein molecules. Biological studying of tritium-labeled insulin showed its physiological activity to be completely retained.

Subsurface methane formation in graphite due to exposure to H+ and D+

International Nuclear Information System (INIS)

Chiu, S.; Haasz, A.A.

1994-01-01

The extent of H-D mixing in the form of mixed-isotope methane formation during simultaneous H + /D + bombardment of graphite was measured and found to be a sensitive function of H + -D + ion range separation. The result strongly supports the model that methane molecules are formed at the end of ion range in the bulk of graphite. A long steadily decreasing transient was observed in the methane emission when bombarding a virgin graphite sample with 10 keV D + at 800 K. The effect was less pronounced for low density fine grain isographites (EK98) than for high density pyrolytic graphite (HPG99) and monocrystal carbons. We propose a model which attributes this transient to the creation of new internal ''surfaces'', formed during ion irradiation along with ion-created micropaths. The increase in internal surface area effectively ''dilutes'' the inner surface hydrogen concentration in the region where incident hydrogen ions thermalize. We propose that, initially, methane molecules are formed mainly on inherent internal surfaces (pore and grain/crystallite boundary surfaces) in the region where hydrogen ions thermalize; then as damage builds up, newly produced internal ''surfaces'' also contribute to methane formation. (orig.)

Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) Applied to Quantitative Proteomics of Bacillus subtilis

DEFF Research Database (Denmark)

Soufi, Boumediene; Kumar, C.; Gnad, F.

2010-01-01

We applied stable isotope labeling by amino acids in cell culture (SILAC) to large-scale quantitative proteomics analyses of the model bacterium Bacillus subtilis in two physiological conditions: growth on succinate and growth under phosphate starvation. Using a B. subtilis strain auxotrophic...... of the most comprehensive quantitative proteomics studies in bacteria, covering more than 75% of the B. subtilis genes expressed in the log phase of growth. Furthermore, we detect and quantify dynamics of 35 Ser/Thr/Tyr phosphorylation sites under growth on succinate, and 10 phosphorylation sites under...

Evaluation of a new component used for isotopic lymphography: colloidal rhenium sulfide sup(99m)Tc labelled

International Nuclear Information System (INIS)

Pecking, A.; Le Mercier, N.; Gobin, R.; Bardy, A.; Najean, Y.

1978-01-01

We have studied for lymphatic scintigraphy a new radiopharmaceutical, sup(99m)Tc-labelled rhenium sulfocolloid. This preliminary study includes 20 adults patients with lymphomas and lymphoedemas. The principal advantage of this drug is its absence of toxicity and local pain, so that a rapid sub-cutaneous injection without local anesthesia is made possible. Good results have been obtained, as well in morphological studies of para-aortic and mammary lymph nodes as for kinetic studies of lymphatic flow in lymphoedemas. No liver and spleen uptake of radio-isotope was observed after foot injection [fr

Hydrogen isotopes confinement in the over-dusted layers of fusion reactor candidate materials

International Nuclear Information System (INIS)

Klepikov, A.Kh.; Tazhibaeva, I.L.; Shestakov, V.P.; Lisitsyn, V.N.; Tuleushev, Yu.Zh.

2001-01-01

In the work the experiments on gas-emission determination from samples of sputtered beryllium, graphite, tungsten, jointly sputtered graphite and tungsten obtained by the magnetron sputtering method at the 'Argamak' facility (National Nuclear Center of the Republic of Kazakhstan), as well as the samples processed on the 'OSPA' plasma accelerator (TRINITI, Russia). The gas-release curves were obtained for indicated samples under different heating velocities within temperature range from 300 up to 1200 K. Gas-release parameters and hydrogen isotopes confinement in these layers were determined. Simulation of hydrogen isotopes gas-emission from samples sputtered layers on the base of obtained experiments with application of simulating programs and TMAP code was carried out

Pseudocapacitive performance of electrodeposited porous Co3O4 film on electrophoretically modified graphite electrodes with carbon nanotubes

Science.gov (United States)

Kazazi, Mahdi; Sedighi, Ali Reza; Mokhtari, Mohammad Amin

2018-05-01

A facile and efficient two-step procedure was developed for the fabrication of a high-performance and binder-free cobalt oxide-carbon nanotubes (CO/CNT) pseudocapacitive electrode. First, CNTs were deposited on the surface of a chemically activated graphite sheet by cathodic electrophoretic deposition technique from their ethanolic suspension. In the next step, a thin film of cobalt oxide was electrodeposited on the CNTs coated graphite substrate by a galvanostatic method, followed by a thermal treatment in air. The structure and morphology of the prepared cobaltite electrode with and without CNT interlayer were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and nitrogen adsorption-desorption measurement. The results indicated that Co3O4 nanoparticles were uniformly attached on the surface of CNTs, to form a porous-structured CO/CNT composite electrode with a high specific surface area of 144.9 m2 g-1. Owing to the superior electrical conductivity of CNTs, high surface area and open porous structure, and improved integrity of the electrode structure, the composite electrode delivered a high areal capacitance of 4.96F cm-2 at a current density of 2 mA cm-2, a superior rate performance (64.7% capacitance retention from 2 mA cm-2 to 50 mA cm-2), as well as excellent cycling stability (91.8% capacitance retention after 2000 cycles), which are higher than those of the pure cobaltite electrode.

Isotopes in day to day life

Science.gov (United States)

1984-06-01

Developments are reported in the use of isotopic labeling and isotope irradiation in agriculture, medical science, hydrology, geochemistry, geophysics, environment pollution detection, and industries. Radioisotope instruments are described as well as techniques for gamma radiography, neutron radiography, and autoradiography. Isotope dating in geology and archaeology is covered. Basic scientific research topics in various areas are listed.

Diamond growth on Fe-Cr-Al alloy by H2-plasma enhanced graphite etching

International Nuclear Information System (INIS)

Li, Y. S.; Hirose, A.

2007-01-01

Without intermediate layer and surface pretreatment, adherent diamond films with high initial nucleation density have been deposited on Fe-15Cr-5Al (wt. %) alloy substrate. The deposition was performed using microwave hydrogen plasma enhanced graphite etching in a wide temperature range from 370 to 740 degree sign C. The high nucleation density and growth rate of diamond are primarily attributed to the unique precursors used (hydrogen plasma etched graphite) and the chemical nature of the substrate. The improvement in diamond adhesion to steel alloys is ascribed to the important role played by Al, mitigation of the catalytic function of iron by suppressing the preferential formation of loose graphite intermediate phase on steel surface

Deuterium pumping and erosion behavior of selected graphite materials under high flux plasma bombardment in PISCES

International Nuclear Information System (INIS)

Hirooka, Y.; Conn, R.W.; Goebel, D.M.; LaBombard, B.; Lehmer, R.; Leung, W.K.; Nygren, R.E.; Ra, Y.

1988-06-01

Deuterium plasma recycling and chemical erosion behavior of selected graphite materials have been investigated using the PISCES-A facility. These materials include: Pyro-graphite; 2D-graphite weave; 4D-graphite weave; and POCO-graphite. Deuterium plasma bombardment conditions are: fluxes around 7 /times/ 10 17 ions s/sup /minus/1/cm/sup /minus/2/; exposure time in the range from 10 to 100 s; bombarding energy of 300 eV; and graphite temperatures between 20 and 120/degree/C. To reduce deuterium plasma recycling, several approaches have been investigated. Erosion due to high-fluence helium plasma conditioning significantly increases the surface porosity of POCO-graphite and 4D-graphite weave whereas little change for 2D-graphite weave and Pyro-graphite. The increased pore openings and refreshed in-pore surface sites are found to reduce the deuterium plasma recycling and chemical erosion rates at transient stages. The steady state recycling rates for these graphite materials can be also correlated to the surface porosity. Surface topographical modification by machined-grooves noticeably reduces the steady state deuterium recycling rate and the impurity emission from the surface. These surface topography effects are attributed to co-deposition of remitted deuterium, chemically sputtered hydrocarbon and physically sputtered carbon under deuterium plasma bombardment. The co-deposited film is found to have a characteristic surface morphology with dendritic microstructures. 18 ref., 4 figs., 1 tab

Quality of Graphite Target for Biological/Biomedical/Environmental Applications of 14C-Accelerator Mass Spectrometry

Science.gov (United States)

2010-01-01

Catalytic graphitization for 14C-accelerator mass spectrometry (14C-AMS) produced various forms of elemental carbon. Our high-throughput Zn reduction method (C/Fe = 1:5, 500 °C, 3 h) produced the AMS target of graphite-coated iron powder (GCIP), a mix of nongraphitic carbon and Fe3C. Crystallinity of the AMS targets of GCIP (nongraphitic carbon) was increased to turbostratic carbon by raising the C/Fe ratio from 1:5 to 1:1 and the graphitization temperature from 500 to 585 °C. The AMS target of GCIP containing turbostratic carbon had a large isotopic fractionation and a low AMS ion current. The AMS target of GCIP containing turbostratic carbon also yielded less accurate/precise 14C-AMS measurements because of the lower graphitization yield and lower thermal conductivity that were caused by the higher C/Fe ratio of 1:1. On the other hand, the AMS target of GCIP containing nongraphitic carbon had higher graphitization yield and better thermal conductivity over the AMS target of GCIP containing turbostratic carbon due to optimal surface area provided by the iron powder. Finally, graphitization yield and thermal conductivity were stronger determinants (over graphite crystallinity) for accurate/precise/high-throughput biological, biomedical, and environmental14C-AMS applications such as absorption, distribution, metabolism, elimination (ADME), and physiologically based pharmacokinetics (PBPK) of nutrients, drugs, phytochemicals, and environmental chemicals. PMID:20163100

Liquid–liquid extraction combined with differential isotope dimethylaminophenacyl labeling for improved metabolomic profiling of organic acids

International Nuclear Information System (INIS)

Peng, Jun; Li, Liang

2013-01-01

Graphical abstract: -- Highlights: •An improved method for profiling the carboxylic acid sub-metabolome is reported. •Liquid–liquid extraction was used for separating the organic acids from the amines. • 12 C/ 13 C-p-dimethylaminophenacyl (DmPA) labeling of the organic acids was carried out on the extract. •Detection interference by amines and labeling efficiency reduction by water were reduced. •About 2500 12 C/ 13 C-peak pairs or putative metabolites could be detected from 20 μL of human urine. -- Abstract: A large fraction of the known human metabolome belong to organic acids. However, comprehensive profiling of the organic acid sub-metabolome is a major analytical challenge. In this work, we report an improved method for detecting organic acid metabolites. This method is based on the use of liquid–liquid extraction (LLE) to selectively extract the organic acids, followed by using differential isotope p-dimethylaminophenacyl (DmPA) labeling of the acid metabolites. The 12 C-/ 13 C-labeled samples are analyzed by liquid chromatography Fourier-transform ion cyclotron resonance mass spectrometry (LC–FTICR–MS). It is shown that this LLE DmPA labeling method offers superior performance over the method of direct DmPA labeling of biofluids such as human urine. LLE of organic acids reduces the interference of amine-containing metabolites that may also react with DmPA. It can also remove water in a biofluid that can reduce the labeling efficiency. Using human urine as an example, it is demonstrated that about 2500 peak pairs or putative metabolites could be detected in a 30-min gradient LC–MS run, which is about 3 times more than that detected in a sample prepared using direct DmPA labeling. About 95% of the 1000 or so matched metabolites to the Human Metabolome Database (HMDB) are organic acids. It is further shown that this method can be used to handle as small as 10 μL of urine. We believe that this method opens the possibility of generating a

Liquid–liquid extraction combined with differential isotope dimethylaminophenacyl labeling for improved metabolomic profiling of organic acids

Energy Technology Data Exchange (ETDEWEB)

Peng, Jun; Li, Liang, E-mail: Liang.Li@ualberta.ca

2013-11-25

Graphical abstract: -- Highlights: •An improved method for profiling the carboxylic acid sub-metabolome is reported. •Liquid–liquid extraction was used for separating the organic acids from the amines. •{sup 12}C/{sup 13}C-p-dimethylaminophenacyl (DmPA) labeling of the organic acids was carried out on the extract. •Detection interference by amines and labeling efficiency reduction by water were reduced. •About 2500 {sup 12}C/{sup 13}C-peak pairs or putative metabolites could be detected from 20 μL of human urine. -- Abstract: A large fraction of the known human metabolome belong to organic acids. However, comprehensive profiling of the organic acid sub-metabolome is a major analytical challenge. In this work, we report an improved method for detecting organic acid metabolites. This method is based on the use of liquid–liquid extraction (LLE) to selectively extract the organic acids, followed by using differential isotope p-dimethylaminophenacyl (DmPA) labeling of the acid metabolites. The {sup 12}C-/{sup 13}C-labeled samples are analyzed by liquid chromatography Fourier-transform ion cyclotron resonance mass spectrometry (LC–FTICR–MS). It is shown that this LLE DmPA labeling method offers superior performance over the method of direct DmPA labeling of biofluids such as human urine. LLE of organic acids reduces the interference of amine-containing metabolites that may also react with DmPA. It can also remove water in a biofluid that can reduce the labeling efficiency. Using human urine as an example, it is demonstrated that about 2500 peak pairs or putative metabolites could be detected in a 30-min gradient LC–MS run, which is about 3 times more than that detected in a sample prepared using direct DmPA labeling. About 95% of the 1000 or so matched metabolites to the Human Metabolome Database (HMDB) are organic acids. It is further shown that this method can be used to handle as small as 10 μL of urine. We believe that this method opens the

Neutron Scattering Study of Nitrogen Adsorbed on Basal Plane Oriented Graphite

DEFF Research Database (Denmark)

Kjems, Jørgen; Passell, L.; Taub, H.

1976-01-01

Thermal-neutron scattering has been used to investigate the structure of nitrogen films adsorbed on Grafoil, a basal-plane-oriented graphite. Diffraction scans were made at coverages between 1/3 of a monolayer and 7/4 monolayers over a temperature range from 10 to 90 K. The observed line shapes...

Metabolic Flux Analysis in Isotope Labeling Experiments Using the Adjoint Approach.

Science.gov (United States)

Mottelet, Stephane; Gaullier, Gil; Sadaka, Georges

2017-01-01

Comprehension of metabolic pathways is considerably enhanced by metabolic flux analysis (MFA-ILE) in isotope labeling experiments. The balance equations are given by hundreds of algebraic (stationary MFA) or ordinary differential equations (nonstationary MFA), and reducing the number of operations is therefore a crucial part of reducing the computation cost. The main bottleneck for deterministic algorithms is the computation of derivatives, particularly for nonstationary MFA. In this article, we explain how the overall identification process may be speeded up by using the adjoint approach to compute the gradient of the residual sum of squares. The proposed approach shows significant improvements in terms of complexity and computation time when it is compared with the usual (direct) approach. Numerical results are obtained for the central metabolic pathways of Escherichia coli and are validated against reference software in the stationary case. The methods and algorithms described in this paper are included in the sysmetab software package distributed under an Open Source license at http://forge.scilab.org/index.php/p/sysmetab/.

Voronoi-Tessellated Graphite Produced by Low-Temperature Catalytic Graphitization from Renewable Resources.

Science.gov (United States)

Zhao, Leyi; Zhao, Xiuyun; Burke, Luke T; Bennett, J Craig; Dunlap, Richard A; Obrovac, Mark N

2017-09-11

A highly crystalline graphite powder was prepared from the low temperature (800-1000 °C) graphitization of renewable hard carbon precursors using a magnesium catalyst. The resulting graphite particles are composed of Voronoi-tessellated regions comprising irregular sheets; each Voronoi-tessellated region having a small "seed" particle located near their centroid on the surface. This suggests nucleated outward growth of graphitic carbon, which has not been previously observed. Each seed particle consists of a spheroidal graphite shell on the inside of which hexagonal graphite platelets are perpendicularly affixed. This results in a unique high surface area graphite with a high degree of graphitization that is made with renewable feedstocks at temperatures far below that conventionally used for artificial graphites. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitating subcellular metabolism with multi-isotope imaging mass spectrometry

Science.gov (United States)

Steinhauser, Matthew L.; Bailey, Andrew; Senyo, Samuel E.; Guillermier, Christelle; Perlstein, Todd S.; Gould, Alex P.; Lee, Richard T.; Lechene, Claude P.

2011-01-01

Mass spectrometry with stable isotope labels has been seminal in discovering the dynamic state of living matter1,2 but is limited to bulk tissues or cells. We developed multi-isotope imaging mass spectrometry (MIMS) that allowed us to view and measure stable isotope incorporation with sub-micron resolution3,4. Here we apply MIMS to diverse organisms, including Drosophila, mice, and humans. We test the “immortal strand hypothesis,” which predicts that during asymmetric stem cell division chromosomes containing older template DNA are segregated to the daughter destined to remain a stem cell, thus insuring lifetime genetic stability. After labeling mice with 15N-thymidine from gestation through post-natal week 8, we find no 15N label retention by dividing small intestinal crypt cells after 4wk chase. In adult mice administered 15N-thymidine pulse-chase, we find that proliferating crypt cells dilute label consistent with random strand segregation. We demonstrate the broad utility of MIMS with proof-of-principle studies of lipid turnover in Drosophila and translation to the human hematopoietic system. These studies show that MIMS provides high-resolution quantitation of stable isotope labels that cannot be obtained using other techniques and that is broadly applicable to biological and medical research. PMID:22246326

Enantio-specific C(sp3)-H activation catalyzed by ruthenium nanoparticles: application to isotopic labeling of molecules of biological interest

International Nuclear Information System (INIS)

Taglang, Celine

2015-01-01

Isotopic labeling with deuterium and tritium is extensively used in chemistry, biology and pharmaceutical research. Numerous methods of labeling by isotopic exchange allow high isotopic enrichments but generally require harsh conditions (high temperatures, acidity). As a consequence, a general, regioselective and smooth labeling method that might be applicable to a wide diversity of substrates remains to develop. In the first part of this thesis, we demonstrated that the use of ruthenium nanoparticles, synthesized by Pr. Bruno Chaudret's team (INSA Toulouse), allowed the mild (2 bar of deuterium gas at 55 C), effective and selective H/D exchange reaction of a large variety of nitrogen-containing compounds, such as pyridines, indoles and primary, secondary and tertiary alkyl amines. The usefulness and the efficiency of this novel methodology was demonstrated by the deuteration of eight nitrogen-containing molecules of biological interest without altering their chemical and stereochemical properties. However, the conservation of the original stereochemistry of an activated chiral C-H center remains a major issue. We studied the reactivity of RuNP(at)PVP on different categories of nitrogen-containing substrates (amines, aminoacids and peptides) in water or in organic solvents. Our results showed that C-H activation of chiral carbons C(sp3) took place efficiently, selectively and, in all cases, with total retention of configuration. The wide range of applications of this procedure was demonstrated by the labeling of three chiral amines, fourteen aminoacids, three aromatic amino esters and four peptides. Moreover, our collaboration with Pr. Romuald Poteau's team (INSA Toulouse) led to the identification of two mechanisms by ab initio simulation in agreement with our experimental results: the σ-bond metathesis mechanism and the oxidative addition mechanism. These two mechanisms imply two vicinal ruthenium atoms leading to the formation an original

Identification of degradation routes of metamitron in soil microcosms using 13C-isotope labeling.

Science.gov (United States)

Wang, Shizong; Miltner, Anja; Nowak, Karolina M

2017-01-01

Metamitron is one of the most commonly used herbicide in sugar beet and flower bulb cultures. Numerous laboratory and field studies on sorption and degradation of metamitron were performed. Detailed biodegradation studies in soil using 13 C-isotope labeling are still missing. Therefore, we aimed at providing a detailed turnover mass balance of 13 C 6 -metamitron in soil microcosms over 80 days. In the biotic system, metamitron mineralized rapidly, and 13 CO 2 finally constituted 60% of the initial 13 C 6 -metamitron equivalents. In abiotic control experiments CO 2 rose to only 7.4% of the initial 13 C 6 -metamitron equivalents. The 13 C label from 13 C 6 -metamitron was incorporated into microbial amino acids that were ultimately stabilized in the soil organic matter forming presumably harmless biogenic residues. Finally, 13 C label from 13 C 6 -metamitron was distributed between the 13 CO 2 and the 13 C-biogenic residues indicating nearly complete biodegradation. The parallel increase of 13 C-alanine, 13 C-glutamate and 13 CO 2 indicates that metamitron was initially biodegraded via the desamino-metamitron route suggesting its relevance in the growth metabolism. In later phases of biodegradation, the "Rhodococcus route" was indicated by the low 13 CO 2 evolution and the high relevance of the pyruvate pathway, which aims at biomolecule synthesis and seems to be related to starvation. This is a first report on the detailed degradation route of metamitron in soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

Direct infusion electrospray ionization–ion mobility–mass spectrometry for comparative profiling of fatty acids based on stable isotope labeling

Energy Technology Data Exchange (ETDEWEB)

Leng, Jiapeng, E-mail: jpleng@126.com [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Guan, Qing [Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center (FUSCC), Shanghai 200032 (China); Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Sun, Tuanqi, E-mail: tuanqisun@163.com [Department of Head and Neck Surgery, Fudan University Shanghai Cancer Center (FUSCC), Shanghai 200032 (China); Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Wang, Haoyang [National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032 (China); Cui, Jianlan; Liu, Qinghao [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Zhang, Zhixu; Zhang, Manyu [Agilent Technologies China Co., Ltd, Shanghai 200080 (China); Guo, Yinlong, E-mail: ylguo@sioc.ac.cn [National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032 (China)

2015-08-05

A rapid method for fatty acids (FAs) comparative profiling based on carboxyl-specific stable isotope labeling (SIL) and direct infusion electrospray ionization–ion mobility–mass spectrometry (ESI–IM–MS) is established. The design of the method takes advantage of the three-dimensional characteristics of IM–MS including drift time, m/z and ion intensity, for comparison of d0-/d6-2,4-dimethoxy-6-piperazin-1-yl pyrimidine (DMPP)-labeled FAs. In particular, without chromatographic separation, the method allowed direct FAs profiling in complex samples due to the advantageous priority of DMPP in signal enhancement as well as the extra resolution that IM–MS offered. Additionally, the d0-/d6-DMPP-labeled FAs showed expected features, including very similar drift times, 6 Da mass deviations, specific reporter ions, similar MS responses, and adherence to the drift time rule regarding the influence of carbon chain length and unsaturation on relative drift times. Therefore, the introduction of isotope analogs minimized the matrix effect and variations in quantification and ensured accurate identification of non-targeted FAs by those typical features. Peak intensity ratios between d0-/d6-DMPP-labeled ions were subsequently used in relative quantification for the detected FAs. The established strategy has been applied successfully in the rapid profiling of trace free FAs between normal and cancerous human thyroid tissues. Sixteen free FAs were found with the increased level with a statistically significant difference (p < 0.05) compared to the normal tissue samples. The integrated SIL technique and ESI–IM–MS are expected to serve as an alternative tool for high-throughput analysis of FAs in complex samples. - Highlights: • A novel method based on IM–MS and SIL was developed for FAs comparative profiling. • Without LC separation, the method allowed direct infusion profiling of FAs in complex samples. • Both of the efficiency and accuracy for FAs analyses

Graphite-based detectors of alkali metals for nuclear power plants

International Nuclear Information System (INIS)

Kalandarishvili, A.G.; Kuchukhidze, V.A.; Sordiya, T.D.; Shartava, Sh.Sh.; Stepennov, B.S.

1993-01-01

The coolants most commonly used in today's fast reactors are alkali metals or their alloys. A major problem in nuclear plant design is leakproofing of the liquid-metal cooling system, and many leak detection methods and safety specifications have been developed as a result. Whatever the safety standards adopted for nuclear plants in different countries, they all rely on the basic fact that control of the contamination and radiation hazards involved requires reliable monitoring equipment. Results are presented of trials with some leak detectors for the alkali-metal circuits of nuclear reactors. The principal component affecting the detector performance is the sensing element. In the detectors graphite was employed, whose laminar structure enables it to absorb efficiently alkali-metal vapors at high temperatures (320--500 K). This produces a continuous series of alkali-metal-graphite solid solutions with distinct electrical, thermal, and other physical properties. The principle of operation of the detectors resides in the characteristic reactions of the metal-graphite system. One detector type uses the change of electrical conductivity of the graphite-film sensor when it is exposed to alkali-metal vapor. In order to minimize the effect of temperature on the resistance the authors prepared composite layers of graphite intercalated with a donor impurity (cesium or barium), and a graphite-nickel material. The addition of a small percentage of cesium, barium, or nickel produces a material whose temperature coefficient of resistance is nearly zero. Used as a sensing element, such a material can eliminate the need for thermostatic control of the detector

Process for purifying graphite

International Nuclear Information System (INIS)

Clausius, R.A.

1985-01-01

A process for purifying graphite comprising: comminuting graphite containing mineral matter to liberate at least a portion of the graphite particles from the mineral matter; mixing the comminuted graphite particles containing mineral matter with water and hydrocarbon oil to form a fluid slurry; separating a water phase containing mineral matter and a hydrocarbon oil phase containing grahite particles; and separating the graphite particles from the hydrocarbon oil to obtain graphite particles reduced in mineral matter. Depending upon the purity of the graphite desired, steps of the process can be repeated one or more times to provide a progressively purer graphite

Calibration of thin-film dosimeters irradiated with 80-120 kev electrons

DEFF Research Database (Denmark)

Helt-Hansen, J.; Miller, A.; McEwen, M.

2004-01-01

A method for calibration of thin-film dosimeters irradiated with 80-120keV electrons has been developed. The method is based on measurement of dose with a totally absorbing graphite calorimeter, and conversion of dose in the graphite calorimeter to dose in the film dosimeter by Monte Carlo calcul......V electron irradiation. The two calibrations were found to be equal within the estimated uncertainties of +/-10% at 1 s.d. (C) 2004 Elsevier Ltd. All rights reserved....

Purification and preparation of graphite oxide from natural graphite

Energy Technology Data Exchange (ETDEWEB)

Panatarani, C., E-mail: c.panatarani@phys.unpad.ac.id; Muthahhari, N.; Joni, I. Made [Instrumentation Systems and Functional Material Processing Laboratory, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Padjadjaran University, Jl. Raya Bandung-Sumedang KM 21, Jatinangor, 45363, Jawa Barat (Indonesia); Rianto, Anton [Grafindo Nusantara Ltd., Belagio Mall Lantai 2, Unit 0 L3-19, Kawasan Mega Kuningan, Kav. B4 No.3, Jakarta Selatan (Indonesia)

2016-03-11

Graphite oxide has attracted much interest as a possible route for preparation of natural graphite in the large-scale production and manipulation of graphene as a material with extraordinary electronic properties. Graphite oxide was prepared by modified Hummers method from purified natural graphite sample from West Kalimantan. We demonstrated that natural graphite is well-purified by acid leaching method. The purified graphite was proceed for intercalating process by modifying Hummers method. The modification is on the reaction time and temperature of the intercalation process. The materials used in the intercalating process are H{sub 2}SO{sub 4} and KMNO{sub 4}. The purified natural graphite is analyzed by carbon content based on Loss on Ignition test. The thermo gravimetricanalysis and the Fouriertransform infrared spectroscopy are performed to investigate the oxidation results of the obtained GO which is indicated by the existence of functional groups. In addition, the X-ray diffraction and energy dispersive X-ray spectroscopy are also applied to characterize respectively for the crystal structure and elemental analysis. The results confirmed that natural graphite samples with 68% carbon content was purified into 97.68 % carbon content. While the intercalation process formed a formation of functional groups in the obtained GO. The results show that the temperature and reaction times have improved the efficiency of the oxidation process. It is concluded that these method could be considered as an important route for large-scale production of graphene.

Electrical Characterization of Graphite/InP Schottky Diodes by I-V-T and C-V Methods

Science.gov (United States)

Tiagulskyi, Stanislav; Yatskiv, Roman; Grym, Jan

2018-02-01

A rectifying junction was prepared by casting a drop of colloidal graphite on the surface of an InP substrate. The electrophysical properties of graphite/InP junctions were investigated in a wide temperature range. Temperature-dependent I-V characteristics of the graphite/InP junctions are explained by the thermionic emission mechanism. The Schottky barrier height (SBH) and the ideality factor were found to be 0.9 eV and 1.47, respectively. The large value of the SBH and its weak temperature dependence are explained by lateral homogeneity of the junction, which is related to the structure of the graphite layer. The moderate disagreement between the current-voltage and capacitance-voltage measurements is attributed to the formation of interfacial native oxide film on the InP surface.

Field experimentation in isotope-aided studies

International Nuclear Information System (INIS)

Zapata, F.

1990-01-01

Isotopic-aided studies involve the application of isotopically labelled fertilizer as tracers for the quantitative and precise determination of the fate of specific nutrient elements in the soil/plant system. The planning of isotopic-aided studies requires a different approach from that followed in the design of normal fertilizer trials because of the cost and supply of isotopically labelled materials, the use of highly specialized equipment and the need for skillful trained staff in the use of isotope techniques both in the field/greenhouse and the laboratory. This report is intended to highlight the main points to be considered while applying those techniques in the field or greenhouse. It has been well established that nuclear techniques are a powerful tool in agricultural research. One should take advantage of the use of such techniques if the following criteria are met: The isotope method is the only way to solve a particular question or to obtain a specific piece of information. There are other methods available for such a purpose but the nuclear method provides a direct and quick means to obtain the needed information resulting in higher economic return

Evaluation of stable isotope labelling strategies for the quantitation of CP4 EPSPS in genetically modified soya

Energy Technology Data Exchange (ETDEWEB)

Ocana, Mireia Fernandez [Centre for Chemical and Bioanalytical Sciences, Royal Holloway, University of London, Egham TW20 0EX (United Kingdom)], E-mail: Mireia.FernandezOcana@pfizer.com; Fraser, Paul D. [Centre for Chemical and Bioanalytical Sciences, Royal Holloway, University of London, Egham TW20 0EX (United Kingdom); Patel, Raj K.P.; Halket, John M. [Specialist Bioanalytical Services Ltd., Royal Holloway, University of London, Egham TW20 0EX (United Kingdom); Bramley, Peter M. [Centre for Chemical and Bioanalytical Sciences, Royal Holloway, University of London, Egham TW20 0EX (United Kingdom)

2009-02-16

The introduction of genetically modified (GM) crops into the market has raised a general alertness relating to the control and safety of foods. The applicability of protein separation hyphenated to mass spectrometry to identify the bacterial enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) protein expressed in GM crops has been previously reported [M.F. Ocana, P.D. Fraser, R.K.P. Patel, J.M. Halket, P.M. Bramley, Rapid Commun. Mass Spectrom. 21 (2007) 319.]. Herein, we investigate the suitability of two strategies that employ heavy stable isotopes, i.e. AQUA and iTRAQ, to quantify different levels of CP4 EPSPS in up to four GM preparations. Both quantification strategies showed potential to determine whether the presence of GM material is above the limits established by the European Union. The AQUA quantification procedure involved protein solubilisation/fractionation and subsequent separation using SDS-PAGE. A segment of the gel in which the protein of interest was located was excised, the stable isotope labeled peptide added at a known concentration and proteolytic digestion initiated. Following recovery of the peptides, on-line separation and detection using LC-MS was carried out. A similar approach was used for the iTRAQ workflow with the exception that proteins were digested in solution and generated tryptic peptides were chemically tagged. Both procedures demonstrated the potential for quantitative detection at 0.5% (w/w) GM soya which is a level below the current European Union's threshold for food-labelling. In this context, a comparison between the two procedures is provided within the present study.

Evaluation of stable isotope labelling strategies for the quantitation of CP4 EPSPS in genetically modified soya

International Nuclear Information System (INIS)

Ocana, Mireia Fernandez; Fraser, Paul D.; Patel, Raj K.P.; Halket, John M.; Bramley, Peter M.

2009-01-01

The introduction of genetically modified (GM) crops into the market has raised a general alertness relating to the control and safety of foods. The applicability of protein separation hyphenated to mass spectrometry to identify the bacterial enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) protein expressed in GM crops has been previously reported [M.F. Ocana, P.D. Fraser, R.K.P. Patel, J.M. Halket, P.M. Bramley, Rapid Commun. Mass Spectrom. 21 (2007) 319.]. Herein, we investigate the suitability of two strategies that employ heavy stable isotopes, i.e. AQUA and iTRAQ, to quantify different levels of CP4 EPSPS in up to four GM preparations. Both quantification strategies showed potential to determine whether the presence of GM material is above the limits established by the European Union. The AQUA quantification procedure involved protein solubilisation/fractionation and subsequent separation using SDS-PAGE. A segment of the gel in which the protein of interest was located was excised, the stable isotope labeled peptide added at a known concentration and proteolytic digestion initiated. Following recovery of the peptides, on-line separation and detection using LC-MS was carried out. A similar approach was used for the iTRAQ workflow with the exception that proteins were digested in solution and generated tryptic peptides were chemically tagged. Both procedures demonstrated the potential for quantitative detection at 0.5% (w/w) GM soya which is a level below the current European Union's threshold for food-labelling. In this context, a comparison between the two procedures is provided within the present study

Electron transfer at boron-doped diamond electrodes modified by graphitic micro-domains

Energy Technology Data Exchange (ETDEWEB)

Mahe, E.; Devilliers, D. [Pierre et Marie Curie Univ., Paris (France). Electrochemistry Lab.; Comninellis, C. [Lausanne Ecole Polytechnique, Lausanne (Switzerland). Groupe de Genie Electrochimique

2006-07-01

Boron-doped (BDD) electrodes have been used in electrolysis procedures for the last 10 years. The mechanical stability of the electrode, its large electrochemical window and its low capacitive current place this new electrode material as an alternative for replacing more costly or toxic materials such as mercury. However, the ferri/ferrocyanide system of boron-doped electrodes has shown contradictory results in the literature. This study proposed a cathodic pre-treatment which relied on the presence of residual graphitic domains formed during the preparation of the BDD film. An experiment was conducted in which the doping procedure was used to control the amount of graphitic phase on the electrode with highly oriented pyrolytic graphite (HOPG) grafted on the BDD surface. Surface characterization with Raman spectroscopy and Scanning Electron Microscopy (SEM) was then carried out using cyclic voltammetry and electrochemical impedance spectroscopy. The electroanalytical determination of the amount of graphitic micro-domains was described and a pulse procedure was proposed which obtained a reproducible surface state. 2 refs., 2 figs.

Direct methods and residue type specific isotope labeling in NMR structure determination and model-driven sequential assignment

International Nuclear Information System (INIS)

Schedlbauer, Andreas; Auer, Renate; Ledolter, Karin; Tollinger, Martin; Kloiber, Karin; Lichtenecker, Roman; Ruedisser, Simon; Hommel, Ulrich; Schmid, Walther; Konrat, Robert; Kontaxis, Georg

2008-01-01

Direct methods in NMR based structure determination start from an unassigned ensemble of unconnected gaseous hydrogen atoms. Under favorable conditions they can produce low resolution structures of proteins. Usually a prohibitively large number of NOEs is required, to solve a protein structure ab-initio, but even with a much smaller set of distance restraints low resolution models can be obtained which resemble a protein fold. One problem is that at such low resolution and in the absence of a force field it is impossible to distinguish the correct protein fold from its mirror image. In a hybrid approach these ambiguous models have the potential to aid in the process of sequential backbone chemical shift assignment when 13 C β and 13 C' shifts are not available for sensitivity reasons. Regardless of the overall fold they enhance the information content of the NOE spectra. These, combined with residue specific labeling and minimal triple-resonance data using 13 C α connectivity can provide almost complete sequential assignment. Strategies for residue type specific labeling with customized isotope labeling patterns are of great advantage in this context. Furthermore, this approach is to some extent error-tolerant with respect to data incompleteness, limited precision of the peak picking, and structural errors caused by misassignment of NOEs

Superhydrophilic graphite surfaces and water-dispersible graphite colloids by electrochemical exfoliation

Energy Technology Data Exchange (ETDEWEB)

Li, Yueh-Feng [Department of Chemical and Materials Engineering, National Central University, Jhongli, 320 Taiwan (China); Chen, Shih-Ming; Lai, Wei-Hao [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung, Hsinchu, 31040 Taiwan (China); Sheng, Yu-Jane [Department of Chemical Engineering, National Taiwan University, Taipei, 106 Taiwan (China); Tsao, Heng-Kwong [Department of Chemical and Materials Engineering, Department of Physics, National Central University, Jhongli, 320 Taiwan (China)

2013-08-14

Superhydrophilic graphite surfaces and water-dispersible graphite colloids are obtained by electrochemical exfoliation with hydrophobic graphite electrodes. Such counterintuitive characteristics are caused by partial oxidation and investigated by examining both graphite electrodes and exfoliated particles after electrolysis. The extent of surface oxidation can be explored through contact angle measurement, scanning electron microscope, electrical sheet resistance, x-ray photoelectron spectroscopy, zeta-potential analyzer, thermogravimetric analysis, UV-visible, and Raman spectroscopy. The degree of wettability of the graphite anode can be altered by the electrolytic current and time. The water contact angle declines generally with increasing the electrolytic current or time. After a sufficient time, the graphite anode becomes superhydrophilic and its hydrophobicity can be recovered by peeling with adhesive tape. This consequence reveals that the anodic graphite is oxidized by oxygen bubbles but the oxidation just occurs at the outer layers of the graphite sheet. Moreover, the characteristics of oxidation revealed by UV peak shift, peak ratio between D and G bands, and negative zeta-potential indicate the presence of graphite oxide on the outer shell of the exfoliated colloids. However, thermogravimetric analysis for the extent of decomposition of oxygen functional groups verifies that the amount of oxygen groups is significantly less than that of graphite oxide prepared via Hummer method. The structure of this partially oxidized graphite may consist of a graphite core covered with an oxidized shell. The properties of the exfoliated colloids are also influenced by pH of the electrolytic solution. As pH is increased, the extent of oxidation descends and the thickness of oxidized shell decreases. Those results reveal that the degree of oxidation of exfoliated nanoparticles can be manipulated simply by controlling pH.

Electrochemical label-free and sensitive nanobiosensing of DNA hybridization by graphene oxide modified pencil graphite electrode.

Science.gov (United States)

Ahour, F; Shamsi, A

2017-09-01

Based on the strong interaction between single-stranded DNA (ss-DNA) and graphene material, we have constructed a novel label-free electrochemical biosensor for rapid and facile detection of short sequences ss-DNA molecules related to hepatitis C virus 1a using graphene oxide modified pencil graphite electrode. The sensing mechanism is based on the superior adsorption of single-stranded DNA to GO over double stranded DNA (ds-DNA). The intrinsic guanine oxidation signal measured by differential pulse voltammetry (DPV) has been used for duplex DNA formation detection. The probe ss-DNA adsorbs onto the surface of GO via the π- π* stacking interactions leading to a strong background guanine oxidation signal. In the presence of complementary target, formation of helix which has weak binding ability to GO induced ds-DNA to release from the electrode surface and significant variation in differential pulse voltammetric response of guanine bases. The results indicated that the oxidation peak current was proportional to the concentration of complementary strand in the range of 0.1 nM-0.5 μM with a detection limit of 4.3 × 10 -11  M. The simple fabricated electrochemical biosensor has high sensitivity, good selectivity, and could be applied as a new platform for a range of target molecules in future. Copyright © 2017 Elsevier Inc. All rights reserved.

Secondary isotope effects on alpha-cleavage reactions

International Nuclear Information System (INIS)

Ingemann, S.; Hammerum, S.

1980-01-01

Kinetic deuterium isotope effects on mass spectral reactions have in several instances been utilized to provide structural information and to answer mechanistic questions. Typically, the influence of the deuterium label on the rate of one of a number of competing reactions has been studied. Secondary isotope effects have usually been assumed to be relatively insignificant in comparison with the observed kinetic effects, even though various workers have shown that secondary isotope effects may indeed exert a considerable influence on the rates of competing simple cleavages. Recent studies have provided quantitative data to show that the mere presence of deuterium atoms up to six bonds away may influence the rate of a simple cleavage reaction. In relation to an investigation of rearrangements accompanying simple cleavage reactions, a semi-quantitative measure was needed of the variation of the secondary isotope effect with the number of bonds between the deuterium label and the point of rupture. The influence has therefore been examined of the presence of remote deuterium atoms on a typical simple cleavage reaction, the α-cleavage of aliphatic amines. As a model compound, N-methyldipentylamine was chosen, systematically labelled with deuterium. (author)

Micro-friction behavior of amorphous carbon films on porous AAO membrane synthesized by the pyrolysis of polyethleneglycol 400

International Nuclear Information System (INIS)

Tu, J.P.; Jiang, C.X.; Guo, S.Y.; Fu, M.F.

2005-01-01

The amorphous carbon films with different degrees of graphitization were synthesized by the pyrolysis of polyethleneglycol 400 infiltrated in the nano-sized pores of anodic aluminum oxide (AAO) membrane. The morphology and microstructure of the carbon films were characterized by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The micro-friction behavior of the amorphous carbon films sliding against GCr15 steel in ambient air was investigated using a ball-on-disk tester at an applied load of 980 mN and a sliding velocity of 0.2 m s -1 . The graphitization degree in the carbon films had effect on the micro-friction properties. In comparison, the amorphous carbon film with high graphitization degree showed low friction coefficient and high wear resistance. An efficient approach was brought for enhancing the friction performance of aluminum

Micro-friction behavior of amorphous carbon films on porous AAO membrane synthesized by the pyrolysis of polyethleneglycol 400

Energy Technology Data Exchange (ETDEWEB)

Tu, J P [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Jiang, C X [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Department of Mechanical and Electronic Engineering, Nanchang University, Nanchang 330029 (China); Guo, S Y [Department of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310033 (China); Fu, M F [Department of Mechanical and Electronic Engineering, Nanchang University, Nanchang 330029 (China)

2005-05-25

The amorphous carbon films with different degrees of graphitization were synthesized by the pyrolysis of polyethleneglycol 400 infiltrated in the nano-sized pores of anodic aluminum oxide (AAO) membrane. The morphology and microstructure of the carbon films were characterized by scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The micro-friction behavior of the amorphous carbon films sliding against GCr15 steel in ambient air was investigated using a ball-on-disk tester at an applied load of 980 mN and a sliding velocity of 0.2 m s{sup -1}. The graphitization degree in the carbon films had effect on the micro-friction properties. In comparison, the amorphous carbon film with high graphitization degree showed low friction coefficient and high wear resistance. An efficient approach was brought for enhancing the friction performance of aluminum.

Thermally exfoliated graphite oxide

Science.gov (United States)

Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

2011-01-01

A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Evaluation of in-vitro cell labelling of mouse epithelia with tritiated thymidine

International Nuclear Information System (INIS)

Mackenzie, I.C.; Ettinger, R.L.

1977-01-01

Various factors affecting the epithelial labelling index recorded following in-vitro incubation of specimens of mouse skin and palatal mucosa with tritiated thymidine were examined. Isotope concentration, specimen size and the period of exposure of autoradiographs prior to development markedly influenced the labelling index recorded but, following standardization of such factors, a reproducible index could be obtained. Labelling indices comparable to those obtained by the standard in-vivo labelling method could be produced by adjustment of isotope concentration in incubation media. Comparison of labelling indices recorded for tissues labelled in-vitro by a standardized method appeared valid but the absolute values of indices so obtained and their comparison with indices resulting from in-vivo labelling methods were of doubtful significance. (author)

Cyclic fatigue of near-isotopic graphite: influence of stress cycle and neutron irradiation

International Nuclear Information System (INIS)

Price, R.J.

1977-11-01

Near-isotropic graphites H-451 and PGX were tested in uniaxial cyclic fatigue, and fatigue life (S-N) curves were generated to a maximum of 10 5 cycles. The stress ratio, R (minimum stress during a cycle divided by maximum stress) ranged from -1 to +0.5. With R = - 1, the homologous stress limits (maximum applied fatigue stress divided by the tensile strength) for 50% specimen survival to 10 5 cycles averaged 0.63 in the axial direction and 0.74 in the radial direction. Corresponding homologous stress limits for 99% specimen survival (99/95 tolerance limits) were 0.48 and 0.53. Higher R-values resulted in longer fatigue lives and increased stress limits. H-451 graphite specimens irradiated with fast neutrons at 1173 to 1263 0 K at fluences of up to 10 26 n/m 2 (equivalent fission fluence) showed fatigue stress limits of about twice the unirradiated levels when the unirradiated tensile strength was used as the basis for normalization

Growth of nanocomposite films from accelerated C60 ions

International Nuclear Information System (INIS)

Pukha, V E; Zubarev, E N; Drozdov, A N; Pugachov, A T; Jeong, S H; Nam, S C

2012-01-01

A beam of accelerated C 60 ions is used to deposit superhard (∼50 GPa) carbon films that exhibit high index plasticity (∼0.13-0.14) and high conductivity (up to 3000 S m -1 ). Transmission electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy are subsequently used to study the microstructure and bond character of the deposited films. The films consist of textured graphite nanocrystals and diamond-like amorphous carbon (DLC). The graphene plane of the nanocrystals is aligned perpendicular to the film surface. It is shown that sp 2 bonds dominate in the films. The percentage of sp 3 bonds depends on the ion energy and the substrate temperature, and does not exceed 40%. The obtained results suggest that a new nanocomposite material consisting of oriented graphite nanocrystals reinforced by a DLC matrix is synthesized. A simple model is proposed to correlate the excellent mechanical properties with the observed structure. (paper)

Dual isotope assays

International Nuclear Information System (INIS)

Smith, G.F.W.; Stevens, R.A.J.; Jacoby, B.

1980-01-01

Dual isotope assays for thyroid function are performed by carrying out a radio-immunoassay for two of thyroxine (T4), tri-iodothyronine (T3), thyroid stimulating hormone (TSH), and thyroxine binding globulin (TBG), by a method wherein a version of one of the thyroid components, preferably T4 or T3 is labelled with Selenium-75 and the version of the other thyroid component is labelled with a different radionuclide, preferably Iodine-125. (author)

Mass spectrometric measurements of norepinephrine synthesis in man from infusion of stable isotope-labelled L-threo-3,4-dihydroxyphenylserine

International Nuclear Information System (INIS)

Suzuki, T.; Sakoda, S.; Ueji, M.; Kishimoto, S.

1985-01-01

The kinetics of stable isotope-labelled L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS), an immediate precursor of (-)-norepinephrine, was studied to investigate the pharmacologic mechanism of its therapeutic effect on orthostatic hypotension in familial amyloid polyneuropathy (FAP) and on akinesia and freezing in parkinsonism. [ 13 C,D]-L-threo-DOPS was synthesized, and 100 mg of the compound was infused for 2 h into two normal subjects, two FAP patients and two patients with the degenerative diseases of the central nervous system. Labelled and endogenous norepinephrine in urine and plasma was assayed simultaneously by gas chromatography/mass spectrometry. The results indicate that the increase in norepinephrine in biological fluids after administration of L-threo-DOPS is attributable mostly to norepinephrine derived from L-threo-DOPS, not to pre-formed endogenous norepinephrine released by L-threo-DOPS

Synthesis of deuterium-labelled compounds for FOTEK project

International Nuclear Information System (INIS)

Joergensen, O.; Egsgaard, H.; Larsen, E.

1996-01-01

In the FoTech project there have been utilized labelled compounds of stable isotopes as internal standards. Some of these compounds are commercially available ( 13 C-labelled PCB congeners, 13 C-labelled diethylstilbestrol for determination of anabolic steroids). Others, like D 9 -clenbuterol, D 3 -clenbuterol, D 3 -zeramol and D 3 -dimetridazol have been synthesized. General aspects of deuterium compounds labelling are considered. (EG)

Proton irradiated graphite grades for a long baseline neutrino facility experiment

International Nuclear Information System (INIS)

Simos, N.; Nocera, P.; Zwaska, R.; Mokhov, N.

2017-01-01

In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF) of the Deep Underground Neutrino Experiment (DUNE) four graphite grades were irradiated with protons in the energy range of 140–180 MeV, to peak fluence of ~6.1×10"2"0 p/cm"2 and irradiation temperatures between 120–200 °C. The test array included POCO ZXF-5Q, Toyo-Tanso IG 430, Carbone-Lorraine 2020 and SGL R7650 grades of graphite. Irradiation was performed at the Brookhaven Linear Isotope Producer. Postirradiation analyses were performed with the objective of (a) comparing their response under the postulated irradiation conditions to guide a graphite grade selection for use as a pion target and (b) understanding changes in physical and mechanical properties as well as microstructure that occurred as a result of the achieved fluence and in particular at this low-temperature regime where pion graphite targets are expected to operate. A further goal of the postirradiation evaluation was to establish a proton-neutron correlation damage on graphite that will allow for the use of a wealth of available neutron-based damage data in proton-based studies and applications. Macroscopic postirradiation analyses as well as energy dispersive x-ray diffraction of 200 KeV x rays at the NSLS synchrotron of Brookhaven National Laboratory were employed. The macroscopic analyses revealed differences in the physical and strength properties of the four grades with behavior however under proton irradiation that qualitatively agrees with that reported for graphite under neutrons for the same low temperature regime and in particular the increase of thermal expansion, strength and Young’s modulus. The proton fluence level of ~10"2"0 cm"-"2 where strength reaches a maximum before it begins to decrease at higher fluences has been identified and it agrees with neutron-induced changes. X-ray diffraction analyses of the proton irradiated graphite revealed for the first time the similarity in

Proton irradiated graphite grades for a long baseline neutrino facility experiment

Directory of Open Access Journals (Sweden)

N. Simos

2017-07-01

Full Text Available In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF of the Deep Underground Neutrino Experiment (DUNE four graphite grades were irradiated with protons in the energy range of 140–180 MeV, to peak fluence of ∼6.1×10^{20}  p/cm^{2} and irradiation temperatures between 120–200 °C. The test array included POCO ZXF-5Q, Toyo-Tanso IG 430, Carbone-Lorraine 2020 and SGL R7650 grades of graphite. Irradiation was performed at the Brookhaven Linear Isotope Producer. Postirradiation analyses were performed with the objective of (a comparing their response under the postulated irradiation conditions to guide a graphite grade selection for use as a pion target and (b understanding changes in physical and mechanical properties as well as microstructure that occurred as a result of the achieved fluence and in particular at this low-temperature regime where pion graphite targets are expected to operate. A further goal of the postirradiation evaluation was to establish a proton-neutron correlation damage on graphite that will allow for the use of a wealth of available neutron-based damage data in proton-based studies and applications. Macroscopic postirradiation analyses as well as energy dispersive x-ray diffraction of 200 KeV x rays at the NSLS synchrotron of Brookhaven National Laboratory were employed. The macroscopic analyses revealed differences in the physical and strength properties of the four grades with behavior however under proton irradiation that qualitatively agrees with that reported for graphite under neutrons for the same low temperature regime and in particular the increase of thermal expansion, strength and Young’s modulus. The proton fluence level of ∼10^{20}  cm^{−2} where strength reaches a maximum before it begins to decrease at higher fluences has been identified and it agrees with neutron-induced changes. X-ray diffraction analyses of the proton irradiated graphite

Proton irradiated graphite grades for a long baseline neutrino facility experiment

Science.gov (United States)

Simos, N.; Nocera, P.; Zhong, Z.; Zwaska, R.; Mokhov, N.; Misek, J.; Ammigan, K.; Hurh, P.; Kotsina, Z.

2017-07-01

In search of a low-Z pion production target for the Long Baseline Neutrino Facility (LBNF) of the Deep Underground Neutrino Experiment (DUNE) four graphite grades were irradiated with protons in the energy range of 140-180 MeV, to peak fluence of ˜6.1 ×1020 p /cm2 and irradiation temperatures between 120 - 200 °C . The test array included POCO ZXF-5Q, Toyo-Tanso IG 430, Carbone-Lorraine 2020 and SGL R7650 grades of graphite. Irradiation was performed at the Brookhaven Linear Isotope Producer. Postirradiation analyses were performed with the objective of (a) comparing their response under the postulated irradiation conditions to guide a graphite grade selection for use as a pion target and (b) understanding changes in physical and mechanical properties as well as microstructure that occurred as a result of the achieved fluence and in particular at this low-temperature regime where pion graphite targets are expected to operate. A further goal of the postirradiation evaluation was to establish a proton-neutron correlation damage on graphite that will allow for the use of a wealth of available neutron-based damage data in proton-based studies and applications. Macroscopic postirradiation analyses as well as energy dispersive x-ray diffraction of 200 KeV x rays at the NSLS synchrotron of Brookhaven National Laboratory were employed. The macroscopic analyses revealed differences in the physical and strength properties of the four grades with behavior however under proton irradiation that qualitatively agrees with that reported for graphite under neutrons for the same low temperature regime and in particular the increase of thermal expansion, strength and Young's modulus. The proton fluence level of ˜1020 cm-2 where strength reaches a maximum before it begins to decrease at higher fluences has been identified and it agrees with neutron-induced changes. X-ray diffraction analyses of the proton irradiated graphite revealed for the first time the similarity in

A theory of stable-isotope dilution mass spectrometry

International Nuclear Information System (INIS)

Pickup, J.F.; McPherson, C.K.

1977-01-01

In order to perform quantitative analysis using stable isotope dilution with mass spectrometry, an equation is derived which describes the relationship between the relative proportions of natural and labelled material and measured isotope ratios

IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C

International Nuclear Information System (INIS)

Wang, Jingzhu; Yang, Rui; Yang, Wenning; Liu, Xin; Xing, Yanyi; Xu, Youxuan

2014-01-01

Highlights: • 13 C labeled testosterone can be used to adjust the isotope ratio of testosterone. • The novel testosterone cannot be detected by the regular IRMS method in doping test. • A method was explored to remove the labeled 13 C. • The established method can be used to detect the manipulated testosterone. - Abstract: Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ 13 C value). However, 13 C labeled standards can be used to control the δ 13 C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the 13 C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ 13 C values between Andro and ANAD (Δδ 13 C Andro–ANAD , ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different 13 C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ 13 C Andro–ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ 13 C Andro–ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3- 13 C labeled standards

A study on compatibilities on transgenic herbicide-resistant rice with wild relatives by using autoradiography of 32P labeled pollen

International Nuclear Information System (INIS)

Liu Linli; Qiang Sheng; Song Xiaoling

2004-01-01

To evaluate the possibility of gene flow through observation of the sexual compatibilities of transgenic herbicide-resistant rice with wild relative by using isotope tracer to label pollen grains, the experiments on radioactivity, tracer mode, autoradiography film and time were conducted. Better procedure was to label pollen grains of transgenic herbicide-resistant rice by culturing the rice in a 1.48 x 10 7 Bq/L 32 P nutrient liquid, to pollinate the labelled pollen grains on the stigmas of barnyard grass (Echinochloa crusgalli var. mitis), Oryza officinalis and weedy rice (Oryza sativa) respectively, and then 3 hour later, to fix these pistils on a piece of glass plate and cover the film of Luck 400 on it for autoradiography. The autoradiographs show that the tube of the transgenic rice's pollens cannot penetrate the stigma of barnyard grass and arrive at embryo sacs to fertilize, so that the possibility of gene flow between them is the lowest; the tube of the labelled pollens can penetrate the stigma of O officinalis and enter the style but can not arrive at embryo sacs to fertilize, so the possibility of gene flow between them is relatively low; and the pollen tube can arrive at the embryo sacs of the weedy rice, so that the possibility of gene flow is relatively high from transgenic herbicide-resistant rice to weedy rice. (authors)

Synthesis of isotopically labeled ketamine

OpenAIRE

Stuchlíková, Lucie

2011-01-01

In this work were synthesized ketamine isotopomers. Ketamine is used in human medicine and veterinary sectors. It has very broad spectrum of pharmacological effects: anesthetic, analgesic, hallucinogenic, bronchodilator, cardiovascular and antidepressive, which is currently in the research. At first was synthesized precursor of ketamine, N- desmethylketamine which was subsequently labeled the deuterium, tritium and carbon- 14. For the determination of purity and identity mass spectrometry and...

Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

Science.gov (United States)

Zhamu, Aruna; Jang, Bor Z.

2014-06-17

A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

Isotope-labelled folic acid derivatives

International Nuclear Information System (INIS)

Lewin, N.; Wong, E.T.

1976-01-01

The suggestion deals with the production of folic acid derivatives suitable as indicators or tracers for analyses of serum folates. These folic acid derivatives contain folic acid which is bound by one or both carboxyl groups to the amino nitrogen of compounds such as, e.g., tyramine, glycyl tyrosine, tyrosine, or the methyl ester of tyrosine. The derivative obtained can be substituted by a gamma emitter, e.g. the iodine isotope I 125. The radioactive derivative is used in the method for the competitive protein bonding to determine endogenic folates in the serum. (UWI) [de

Thermal migration of deuterium implanted in graphite: Influence of free surface proximity and structure

Energy Technology Data Exchange (ETDEWEB)

Le Guillou, M. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, F-69622 Villeurbanne cedex (France); Moncoffre, N., E-mail: n.moncoffre@ipnl.in2p3.fr [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, F-69622 Villeurbanne cedex (France); Toulhoat, N. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, F-69622 Villeurbanne cedex (France); CEA/DEN – Centre de Saclay, F-91191 Gif-sur-Yvette cedex (France); Pipon, Y. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3 UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, F-69622 Villeurbanne cedex (France); Institut Universitaire Technologique, Université Claude Bernard Lyon 1, Université de Lyon, F-69622 Villeurbanne cedex (France); Ammar, M.R. [CNRS, CEMHTI UPR3079, Université Orléans, CS90055, F-45071 Orléans cedex 2 (France); Rouzaud, J.N.; Deldicque, D. [Laboratoire de Géologie de l’Ecole Normale Supérieure, Paris, UMR CNRS ENS 8538, F-75231 Paris cedex 5 (France)

2016-03-15

This paper is a contribution to the study of the behavior of activation products produced in irradiated nuclear graphite, graphite being the moderator of the first French generation of CO{sub 2} cooled nuclear fission reactors. This paper is focused on the thermal release of Tritium, a major contributor to the initial activity, taking into account the role of the free surfaces (open pores and graphite surface). Two kinds of graphite were compared. On one hand, Highly Oriented Pyrolitic Graphite (HOPG), a model well graphitized graphite, and on the other hand, SLA2, a porous less graphitized nuclear graphite. Deuterium ion implantation at three different energies 70, 200 and 390 keV allows simulating the presence of Tritium at three different depths, corresponding respectively to projected ranges R{sub p} of 0.75, 1.7 and 3.2 μm. The D isotopic tracing is performed thanks to the D({sup 3}He,p){sup 4}He nuclear reaction. The graphite structure is studied by Raman microspectrometry. Thermal annealing is performed in the temperature range 200–1200 °C up to 300 h annealing time. As observed in a previous study, the results show that the D release occurs according to three kinetic regimes: a rapid permeation through open pores, a transient regime corresponding to detrapping and diffusion of D located at low energy sites correlated to the edges of crystallites and finally a saturation regime attributed to detrapping of interstitial D located at high energy sites inside the crystallites. Below 600 °C, D release is negligible whatever the implantation depth and the graphite type. The present paper clearly puts forward that above 600 °C, the D release decreases at deeper implantation depths and strongly depends on the graphite structure. In HOPG where high energy sites are more abundant, the D release is less dependent on the surface proximity compared to SLA2. In SLA2, in which the low energy sites prevail, the D release curves are clearly shifted towards lower

Interfacial effects in ZnO nanotubes/needle-structured graphitic diamond nanohybrid for detecting dissolved acetone at room temperature

Science.gov (United States)

Kathiravan, Deepa; Huang, Bohr-Ran; Saravanan, Adhimoorthy; Yeh, Chien-Jui; Leou, Keh-Chyang; Lin, I.-Nan

2017-12-01

A high-performance ZnO nanotubes (ZNTs)/needle-structured graphitic diamond (NGD) nanohybrid material was prepared and observed the electrochemical sensing properties of liquid acetone in water. Initially, we synthesized NGD film using bias-enhanced growth (BEG) process. Afterwards, a well-etched ZNTs were spatially grown on the NGD film using simple hydrothermal method, and utilized as sensing material for assemble an electrochemical sensor (via EGFET configuration) operating at room temperature. The systematic investigations depict the ultra-high sensing properties attained from ZNTs grown on NGD film. The NGD film mostly have needle or wire shaped diamond grains, which contributes extremely high electrical conductivity. Furthermore, needle shaped diamond grains cover with multi-layer graphitic material generates conduction channels for ZNTs and leads to enhance the oxygen residuals and species. The material stability and conductivity of NGD as well the defects exist with oxygen vacancies in ZNTs offers superior sensing properties. Thus, the interesting combination of these wide band gap semiconductor materials exhibit high sensor response (89 mV/mL), high stability and long-term reliability (tested after 60 days).

AES study of the reaction between a thin Fe-film and β-SiC (100) surface

International Nuclear Information System (INIS)

Mizokawa, Yusuke; Nakanishi, Shigemitsu; Miyase, Sunao

1989-01-01

The solid state reaction between thin Fe-films and β-SiC(100) in UHV has been studied using AES. Even at room temperature, the reaction between the thin Fe-film and SiC occurred and formed Fe-silicide and graphite with a minor product of Fe-carbide (Fe 3 C). The reaction proceeded with an increase of Fe-coverage to some extent. With annealing of 15 A-Fe-film/SiC below 540degC, the Fe-silicide formation was accelerated, but because the amount of available Fe was small, the dissolved carbon atoms were forced to form not the Fe-carbide but the graphite phase. Above 640degC, the Fe-silicide started to decompose and the carbon atoms diffused to the surface and formed surface graphite layers. With annealing at 1080degC, the free-Si segregats at the surface and formed Si-Si bonds, as well as the Si-C bonds consuming the surface graphite phase. (author)

Negative ion ESI-MS analysis of natural yellow dye flavonoids--An isotopic labelling study

Science.gov (United States)

McNab, Hamish; Ferreira, Ester S. B.; Hulme, Alison N.; Quye, Anita

2009-07-01

Flavonoids are amongst the most commonly used natural yellow colourants in paintings, as lakes, and in historical textiles as mordant dyes. In this paper, evidence from isotopically labelled substrates is used to propose negative ion electrospray collision induced decomposition mechanisms of flavones, flavonols and an isoflavone. These mechanisms include a retro-Diels-Alder fragmentation (observed for flavones and flavonols) and an M-122 fragmentation (characteristic of 3',4'-dihydroxyflavonols). In addition, the presence of a m/z 125 fragment ion is shown to be characteristic of 2'-hydroxyflavonols and an ion at m/z 149 is shown to be characteristic of 4'-hydroxyflavones. Applications of these methods are exemplified by the identification of a minor component of Dyer's camomile (Anthemis tinctoria L.) and the identification of the dye source in green threads sampled from an 18th Century Scottish tartan fragment.

Deciphering systemic wound responses of the pumpkin extrafascicular phloem by metabolomics and stable isotope-coded protein labeling.

Science.gov (United States)

Gaupels, Frank; Sarioglu, Hakan; Beckmann, Manfred; Hause, Bettina; Spannagl, Manuel; Draper, John; Lindermayr, Christian; Durner, Jörg

2012-12-01

In cucurbits, phloem latex exudes from cut sieve tubes of the extrafascicular phloem (EFP), serving in defense against herbivores. We analyzed inducible defense mechanisms in the EFP of pumpkin (Cucurbita maxima) after leaf damage. As an early systemic response, wounding elicited transient accumulation of jasmonates and a decrease in exudation probably due to partial sieve tube occlusion by callose. The energy status of the EFP was enhanced as indicated by increased levels of ATP, phosphate, and intermediates of the citric acid cycle. Gas chromatography coupled to mass spectrometry also revealed that sucrose transport, gluconeogenesis/glycolysis, and amino acid metabolism were up-regulated after wounding. Combining ProteoMiner technology for the enrichment of low-abundance proteins with stable isotope-coded protein labeling, we identified 51 wound-regulated phloem proteins. Two Sucrose-Nonfermenting1-related protein kinases and a 32-kD 14-3-3 protein are candidate central regulators of stress metabolism in the EFP. Other proteins, such as the Silverleaf Whitefly-Induced Protein1, Mitogen Activated Protein Kinase6, and Heat Shock Protein81, have known defensive functions. Isotope-coded protein labeling and western-blot analyses indicated that Cyclophilin18 is a reliable marker for stress responses of the EFP. As a hint toward the induction of redox signaling, we have observed delayed oxidation-triggered polymerization of the major Phloem Protein1 (PP1) and PP2, which correlated with a decline in carbonylation of PP2. In sum, wounding triggered transient sieve tube occlusion, enhanced energy metabolism, and accumulation of defense-related proteins in the pumpkin EFP. The systemic wound response was mediated by jasmonate and redox signaling.

Isotopic labeling for the understanding of the alteration of limestone used in built cultural heritage