Analysis of abused drugs by selected ion monitoring: quantitative comparison of electron impact and chemical ionization

International Nuclear Information System (INIS)

Foltz, R.L.; Knowlton, D.A.; Lin, D.C.K.; Fentiman, A.F. Jr.

1975-01-01

A comparison was made of the relative sensitivities of electron impact and chemical ionization when used for selected ion monitoring analysis of commonly abused drugs. For most of the drugs examined chemical ionization using ammonia as the reactant gas gave the largest single m/e ion current response per unit weight of sample. However, if maximum sensitivity is desired it is important to evaluate electron impact and chemical ionization with respect to both maximum response and degree of interference from background and endogenous materials

Mechanism of Interaction between Ionizing Radiation and Chemicals

International Nuclear Information System (INIS)

Kim, Jin Kyu; Lee, B. H.; Shin, H. S.

2008-03-01

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals . Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland

Mechanism of Interaction between Ionizing Radiation and Chemicals

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Lee, B H; Shin, H S [and others

2008-03-15

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals{sup .} Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland.

Mechanism of Interaction between Ionizing Radiation and Chemicals

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Lee, B. H.; Shin, H. S. (and others)

2008-03-15

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals{sup .} Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland.

NCI Alliance for Nanotechnology in Cancer

Science.gov (United States)

The NCI Alliance for Nanotechnology in Cancer funds the Cancer Nanotechnology Training Centers collectively with the NCI Cancer Training Center. Find out about the funded Centers, to date, that train our next generation of scientists in the field of Canc

Highly informative multiclass profiling of lipids by ultra-high performance liquid chromatography - Low resolution (quadrupole) mass spectrometry by using electrospray ionization and atmospheric pressure chemical ionization interfaces.

Science.gov (United States)

Beccaria, Marco; Inferrera, Veronica; Rigano, Francesca; Gorynski, Krzysztof; Purcaro, Giorgia; Pawliszyn, Janusz; Dugo, Paola; Mondello, Luigi

2017-08-04

A simple, fast, and versatile method, using an ultra-high performance liquid chromatography system coupled with a low resolution (single quadrupole) mass spectrometer was optimized to perform multiclass lipid profiling of human plasma. Particular attention was made to develop a method suitable for both electrospray ionization and atmospheric pressure chemical ionization interfaces (sequentially in positive- and negative-ion mode), without any modification of the chromatographic conditions (mobile phase, flow-rate, gradient, etc.). Emphasis was given to the extrapolation of the structural information based on the fragmentation pattern obtained using atmospheric pressure chemical ionization interface, under each different ionization condition, highlighting the complementary information obtained using the electrospray ionization interface, of support for related molecule ions identification. Furthermore, mass spectra of phosphatidylserine and phosphatidylinositol obtained using the atmospheric pressure chemical ionization interface are reported and discussed for the first time. Copyright © 2017 Elsevier B.V. All rights reserved.

NCI Holds on to Defelice Cup | Poster

Science.gov (United States)

NCI kept the Defelice Cup trophy this year after beating Leidos Biomedical Research, 15 to 9, at the 10th annual Ronald H. Defelice Golf Tournament held on Columbus Day. Sixteen players on each team battled it out at the yearly contractor vs. government tournament held at Rattlewood Golf Course in Mount Airy, Md. NCI leads the series 6–4. “The score was the highest NCI margin

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.; Martinek, K.

1977-01-01

Papers published in 1976 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.

1976-03-01

Papers published in 1974 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.; Martinek, K.

1977-01-01

Papers published in 1975 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

License Agreements | NCI Technology Transfer Center | TTC

Science.gov (United States)

NCI Technology Transfer Center (TTC) licenses the discoveries of NCI and nine other NIH Institutes so new technologies can be developed and commercialized, to convert them into public health benefits.

NCI & Division Obligations

Science.gov (United States)

Displays obligations for grants, contracts, training fellowships, intramural research, and management and support, including the number of grant awards, funding amounts, and percent of the total NCI budget.

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Hannig, H.; Dlaske, R.; Haehn, J.; Martinek, K.

1980-01-01

Papers published in 1978 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in in-vivo and model systems, the biochemical, pharmacological and toxic effects, and modes of action of radioprotective agents are described and the trends in this field of research appreciated. (author)

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Hannig, H.; Dlaske, R.; Papendieck, W.; Martinek, K.; Haehn, J.

1982-01-01

Papers published in 1979 and 1980 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in in-vivo and model systems, the biochemical, pharmacological and toxic effects, and modes of action of radioprotective agents are described and the trends in this field of research estimated. (author)

Physical and chemical changes in water pollutants caused by ionizing radiations

International Nuclear Information System (INIS)

Vacek, K.

1978-01-01

Ionization and excitation as primary effects of ionizing radiation form secondary activated intermediary products (H and OH radicals and hydrated electrons esub(aq) - ) in water systems, which act on all in substances present in water. Physical and chemical changes speeding the sludge sedimentation in waste-water show complex dependences. It is, however, possible to prove them even at low radiation doses (0.07 to 0.35 kJ/kg). Chemical effects can be observed at higher radiation doses (1 to 10 kJ/kg) and are based on oxidative destruction of pollutants. Some of these reactions may be based on chain mechanisms (phenol oxidizing in water), but there are limited chances for application of these chain mechanisms in waste-water systems. Slight damage of biologically important macromolecules leads to changes, or even stops biological processes. Therefore, biological effects of ionizing radiation have the most remarkable impact. The utilization of these reactions in water management may be possible in suppressing biological ochration (ochre sedimentation) in wells and for ensuring hygienic conditions of sludge in waste-water processing for agrotechnical purposes. (author)

NCI collaborates with Multiple Myeloma Research Foundation

Science.gov (United States)

The National Cancer Institute (NCI) announced a collaboration with the Multiple Myeloma Research Foundation (MMRF) to incorporate MMRF's wealth of genomic and clinical data on the disease into the NCI Genomic Data Commons (GDC), a publicly available datab

Mutagenic effect of ionizing radiation and chemical and environmental agents in Tradescantia

International Nuclear Information System (INIS)

Cebulska-Wasilewska, A.

1988-01-01

The studies covered the following problems: an influence of some environmental agents on the mutagenic effectiveness of ionizing radiation, interaction between ionizing radiation and chemical mutagens in the induction of somatic mutations and also an application of Tradescantia model system for biological monitoring. The studies showed that the pretreatment of Tradescantia plants with sodium fluoride or the modification of the soil composition with dolomite admixture, visibly influences plants radiosensitivity. The analysis of the changes in the dose-response curves suggested that the employed agents were influencing in different ways the repair processes of the DNA. The studies on the interaction between agents proved that the synergistic effect occurs in case of combined action of ionizing radiation with such chemical mutagens as ethyl methansulfonate or 1,2 dibromomethane. It was also discovered that in the range of low doses the effect was proportional to radiation dose and total exposition to chemical mutagen. The field application of Tradescantia method defined the mutagenicity of air pollution in the Cracow area. The highest frequencies of mutations were detected after the Chernobyl accident and after the damage of the filters in the Pharmaceutical Plant. The applied method was evaluated in respect of its usefulness for biological monitoring of environmental pollution. 163 refs. (author)

Comparison of Atmospheric Pressure Chemical Ionization and Field Ionization Mass Spectrometry for the Analysis of Large Saturated Hydrocarbons.

Science.gov (United States)

Jin, Chunfen; Viidanoja, Jyrki; Li, Mingzhe; Zhang, Yuyang; Ikonen, Elias; Root, Andrew; Romanczyk, Mark; Manheim, Jeremy; Dziekonski, Eric; Kenttämaa, Hilkka I

2016-11-01

Direct infusion atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was compared to field ionization mass spectrometry (FI-MS) for the determination of hydrocarbon class distributions in lubricant base oils. When positive ion mode APCI with oxygen as the ion source gas was employed to ionize saturated hydrocarbon model compounds (M) in hexane, only stable [M - H] + ions were produced. Ion-molecule reaction studies performed in a linear quadrupole ion trap suggested that fragment ions of ionized hexane can ionize saturated hydrocarbons via hydride abstraction with minimal fragmentation. Hence, APCI-MS shows potential as an alternative of FI-MS in lubricant base oil analysis. Indeed, the APCI-MS method gave similar average molecular weights and hydrocarbon class distributions as FI-MS for three lubricant base oils. However, the reproducibility of APCI-MS method was found to be substantially better than for FI-MS. The paraffinic content determined using the APCI-MS and FI-MS methods for the base oils was similar. The average number of carbons in paraffinic chains followed the same increasing trend from low viscosity to high viscosity base oils for the two methods.

Quantification of low levels of organochlorine pesticides using small volumes ({<=}100 {mu}l) of plasma of wild birds through gas chromatography negative chemical ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Rivera-Rodriguez, Laura B. [Centro de Investigaciones Biologicas del Noroeste, S.C., Environmental Planning and Conservation Program, Mar Bermejo No. 195, Col. Playa Palo de Santa Rita, Ado. Postal 128, La Paz, BCS. 23090 (Mexico)]. E-mail: lrivera04@cibnor.mx; Rodriguez-Estrella, Ricardo [Centro de Investigaciones Biologicas del Noroeste, S.C., Environmental Planning and Conservation Program, Mar Bermejo No. 195, Col. Playa Palo de Santa Rita, Ado. Postal 128, La Paz, BCS. 23090 (Mexico); Ellington, James Jackson [National Exposure Research Laboratory, US Environmental Protection Agency, 960 College Station Road, Athens, GA 30605 (United States); Evans, John J. [National Exposure Research Laboratory, US Environmental Protection Agency, 960 College Station Road, Athens, GA 30605 (United States); Senior Service America Inc. (United States)

2007-07-15

A solid phase extraction and gas chromatography with negative chemical ionization mass spectrometry in scan mode (GC-NCI-MS) method was developed to identify and quantify for the first time low levels of organochlorine pesticides (OCs) in plasma samples of less than 100 {mu}l from wild birds. The method detection limits ranged from 0.012 to 0.102 pg/{mu}l and the method reporting limit from 0.036 to 0.307 pg/{mu}l for {alpha}, {gamma}, {beta} and {delta}-hexachlorocyclohexane (HCH), heptachlor, aldrin, heptachlor epoxide, endosulfan I, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), dieldrin, endrin, endosulfan-II, endrin-aldehyde and endosulfan-sulfate. Pesticide levels in small serum samples from individual Falco sparverius, Sturnella neglecta, Mimus polyglottos and Columbina passerina were quantified. Concentrations ranged from not detected (n/d) to 204.9 pg/{mu}l for some OC pesticides. All levels in the food web in and around cultivated areas showed the presence of pesticides notwithstanding the small areas for agriculture existing in the desert of Baja California peninsula. - This technique allows small birds to be used as indicators of chemical contamination in habitats because pesticides can be quantified in very small volumes of plasma.

CRADA Payment Options | NCI Technology Transfer Center | TTC

Science.gov (United States)

NCI TTC CRADA PAYMENT OPTIONS: Electronic Payments by Wire Transfer via Fedwire, Mail a check to the Institute or Center, or Automated Clearing House (ACH)/Electronic Funds Transfer (ETF) payments via Pay.gov (NCI ONLY).

Atmospheric pressure chemical ionization studies of non-polar isomeric hydrocarbons using ion mobility spectrometry and mass spectrometry with different ionization techniques

Science.gov (United States)

Borsdorf, H.; Nazarov, E. G.; Eiceman, G. A.

2002-01-01

The ionization pathways were determined for sets of isomeric non-polar hydrocarbons (structural isomers, cis/trans isomers) using ion mobility spectrometry and mass spectrometry with different techniques of atmospheric pressure chemical ionization to assess the influence of structural features on ion formation. Depending on the structural features, different ions were observed using mass spectrometry. Unsaturated hydrocarbons formed mostly [M - 1]+ and [(M - 1)2H]+ ions while mainly [M - 3]+ and [(M - 3)H2O]+ ions were found for saturated cis/trans isomers using photoionization and 63Ni ionization. These ionization methods and corona discharge ionization were used for ion mobility measurements of these compounds. Different ions were detected for compounds with different structural features. 63Ni ionization and photoionization provide comparable ions for every set of isomers. The product ions formed can be clearly attributed to the structures identified. However, differences in relative abundance of product ions were found. Although corona discharge ionization permits the most sensitive detection of non-polar hydrocarbons, the spectra detected are complex and differ from those obtained with 63Ni ionization and photoionization. c. 2002 American Society for Mass Spectrometry.

Effect of pH and dissociation on the fate and exposure of ionizable chemicals

DEFF Research Database (Denmark)

Franco, Antonio; Trapp, Stefan

2010-01-01

Ionizable organic chemicals comprise an important fraction of pharmaceuticals, pesticides as well as industrial chemicals. It has been estimated that 33% of the preregistered REACH substances is mostly ionized at pH 7. To extend the appliccability of existing exposure models, a Multimedia Activity...... parameters. The sensitivity analysis showed that the parameters describing ionization, pH and the dissociation constant (pKa), are among the most sensitive model parameters. The uncertainty analysis, however, indicated that these parameters are not the major source of uncertainty, which statistically...... and sediments. In most cases, the uncertainty of PECs and of persistance is largely explained by the uncertainty of (bio)degradation rates, which may be caused by model assumptions, experimental or estimation errors or by the environmental variability, including the effect of pH....

NCI Visuals Online

Science.gov (United States)

NCI Visuals Online contains images from the collections of the National Cancer Institute's Office of Communications and Public Liaison, including general biomedical and science-related images, cancer-specific scientific and patient care-related images, and portraits of directors and staff of the National Cancer Institute.

Physical and chemical effects of ionizing radiation, application for conservation of food products

International Nuclear Information System (INIS)

Foos, J.

1986-01-01

The author sets about ''defining the parameters'' and ''describing the systems'' by means of which ionizing radiation can be used to conserve food products and make them more healthy. After defining the different types of radiation, he goes on to examine interactions between these types of radiation and the food to be processed, including the chemical reactions caused by the ionization and excitation processes [fr

Negative chemical ionization gas chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry and automated accurate mass data processing for determination of pesticides in fruit and vegetables.

Science.gov (United States)

Besil, Natalia; Uclés, Samanta; Mezcúa, Milagros; Heinzen, Horacio; Fernández-Alba, Amadeo R

2015-08-01

Gas chromatography coupled to high resolution hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS), operating in negative chemical ionization (NCI) mode and combining full scan with MSMS experiments using accurate mass analysis, has been explored for the automated determination of pesticide residues in fruit and vegetables. Seventy compounds were included in this approach where 50 % of them are not approved by the EU legislation. A global 76 % of the analytes could be identified at 1 μg kg(-1). Recovery studies were developed at three concentration levels (1, 5, and 10 μg kg(-1)). Seventy-seven percent of the detected pesticides at the lowest level yielded recoveries within the 70 %-120 % range, whereas 94 % could be quantified at 5 μg kg(-1), and the 100 % were determined at 10 μg kg(-1). Good repeatability, expressed as relative standard deviation (RSD home-made database was developed and applied to an automatic accurate mass data processing. Measured mass accuracies of the generated ions were mainly less than 5 ppm for at least one diagnostic ion. When only one ion was obtained in the single-stage NCI-MS, a representative product ion from MSMS experiments was used as identification criterion. A total of 30 real samples were analyzed and 67 % of the samples were positive for 12 different pesticides in the range 1.0-1321.3 μg kg(-1).

Quantification of low levels of organochlorine pesticides using small volumes (≤100 μl) of plasma of wild birds through gas chromatography negative chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Rivera-Rodriguez, Laura B.; Rodriguez-Estrella, Ricardo; Ellington, James Jackson; Evans, John J.

2007-01-01

A solid phase extraction and gas chromatography with negative chemical ionization mass spectrometry in scan mode (GC-NCI-MS) method was developed to identify and quantify for the first time low levels of organochlorine pesticides (OCs) in plasma samples of less than 100 μl from wild birds. The method detection limits ranged from 0.012 to 0.102 pg/μl and the method reporting limit from 0.036 to 0.307 pg/μl for α, γ, β and δ-hexachlorocyclohexane (HCH), heptachlor, aldrin, heptachlor epoxide, endosulfan I, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), dieldrin, endrin, endosulfan-II, endrin-aldehyde and endosulfan-sulfate. Pesticide levels in small serum samples from individual Falco sparverius, Sturnella neglecta, Mimus polyglottos and Columbina passerina were quantified. Concentrations ranged from not detected (n/d) to 204.9 pg/μl for some OC pesticides. All levels in the food web in and around cultivated areas showed the presence of pesticides notwithstanding the small areas for agriculture existing in the desert of Baja California peninsula. - This technique allows small birds to be used as indicators of chemical contamination in habitats because pesticides can be quantified in very small volumes of plasma

Comparison of extraction techniques and mass spectrometric ionization modes in the analysis of wine volatile carbonyls

International Nuclear Information System (INIS)

Zapata, Julian; Mateo-Vivaracho, Laura; Cacho, Juan; Ferreira, Vicente

2010-01-01

This work presents a comparative study of the analytical characteristics of two methods for the analysis of carbonyl compounds in wine, both based on the derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). In the first method derivatives are formed in the solid phase extraction (SPE) cartridge in which the analytes have been previously isolated, while in the second method derivatives are formed in a solid phase microextraction (SPME) fibre saturated with vapors of the reagent and exposed to the sample headspace. In both cases detection has been carried out by electron impact (EI) or negative chemical ionization (NCI) mass spectrometry. The possibility of determining haloanisols simultaneously has been also considered. The method based on SPE presents, in general, better analytical properties than the SPME one. Although linearity was satisfactory for both methods (R 2 > 0.99), repeatability of the SPE method (RSD < 10%) was better than that obtained with SPME (9% < RSD < 20%). Detection limits obtained with EI are better for the SPE method except for trihaloanisols, while with NCI detection limits for both strategies are comparable, although the SPME strategy presents worse results for ketones and methional. Detection limits are always lower with NCI, being the improvement most notable for SPME. Recovery experiments show that in the case of SPE, uncertainties are lower than 12% in all cases, while with the SPME method the imprecision plus the existence of matrix effects make the global uncertainty to be higher than 15%.

Comparison of extraction techniques and mass spectrometric ionization modes in the analysis of wine volatile carbonyls

Energy Technology Data Exchange (ETDEWEB)

Zapata, Julian; Mateo-Vivaracho, Laura; Cacho, Juan [Laboratory for Flavor Analysis and Enology, Institute of Engineering of Aragon, I3A, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza (Spain); Ferreira, Vicente, E-mail: vferre@unizar.es [Laboratory for Flavor Analysis and Enology, Institute of Engineering of Aragon, I3A, Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza (Spain)

2010-02-15

This work presents a comparative study of the analytical characteristics of two methods for the analysis of carbonyl compounds in wine, both based on the derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). In the first method derivatives are formed in the solid phase extraction (SPE) cartridge in which the analytes have been previously isolated, while in the second method derivatives are formed in a solid phase microextraction (SPME) fibre saturated with vapors of the reagent and exposed to the sample headspace. In both cases detection has been carried out by electron impact (EI) or negative chemical ionization (NCI) mass spectrometry. The possibility of determining haloanisols simultaneously has been also considered. The method based on SPE presents, in general, better analytical properties than the SPME one. Although linearity was satisfactory for both methods (R{sup 2} > 0.99), repeatability of the SPE method (RSD < 10%) was better than that obtained with SPME (9% < RSD < 20%). Detection limits obtained with EI are better for the SPE method except for trihaloanisols, while with NCI detection limits for both strategies are comparable, although the SPME strategy presents worse results for ketones and methional. Detection limits are always lower with NCI, being the improvement most notable for SPME. Recovery experiments show that in the case of SPE, uncertainties are lower than 12% in all cases, while with the SPME method the imprecision plus the existence of matrix effects make the global uncertainty to be higher than 15%.

Analysis of 125I-[Tyr3] octreotide receptors of NCI-H466 cell line

International Nuclear Information System (INIS)

Sun Junjie; Fan Wo; Xu Yujie; Zhang Youjiu; Zhu Ran

2002-01-01

Objective: To study the affinity of small cell lung carcinoma to [Tyr 3 ] octreotide (TOC). Methods: Taking 125 I-[Tyr 3 ] octreotide (labeled by chloramine-T method), as the ligand, small cell lung carcinoma NCI-H466 cell line was inspected for the receptor-binding points and affinity constant. Results: The radio-chemical purity of 125 I-TOC purified through sephadex G-10 was higher than 95%. Receptor analysis study showed that the expression of somatostatin receptors on NCI-H446 cells was numerous (Bmax = 1.17 x 10 5 /cell) with strong affinity to 125 I-TOC (Kd = 0.56 nM). Conclusion: Labeled TOC could be used for small cell lung carcinoma receptor imaging and radio-pharmaceutical therapy

International Fellows of NCI at Frederick | Poster

Science.gov (United States)

Each year, the Employee Diversity Team (EDT) acknowledges members of the NCI at Frederick Community for their achievements and contributions towards the mission of facility.  Historically, the team has profiled the “Women of NCI at Frederick,” but this year, the team decided to instead shed light on the diverse and successful individuals who make up the international fellows community.

Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry

NARCIS (Netherlands)

Guo, Xinghua; Bruins, Andries P.; Covey, Thomas R.

2006-01-01

The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion

NCI at Frederick Ebola Response Team | Poster

Science.gov (United States)

Editor’s note: This article was adapted from the Employee Diversity Team’s display case exhibit “Recognizing the NCI at Frederick Ebola Response Team,” in the lobby of Building 549. The Poster staff recognizes that this article does not include everyone who was involved in the response to the Ebola crisis, both at NCI at Frederick and in Africa. When the Ebola crisis broke out

Chemical characterization of synthetic cannabinoids by electrospray ionization FT-ICR mass spectrometry.

Science.gov (United States)

Kill, Jade B; Oliveira, Izabela F; Tose, Lilian V; Costa, Helber B; Kuster, Ricardo M; Machado, Leandro F; Correia, Radigya M; Rodrigues, Rayza R T; Vasconcellos, Géssica A; Vaz, Boniek G; Romão, Wanderson

2016-09-01

The synthetic cannabinoids (SCs) represent the most recent advent of the new psychotropic substances (NPS) and has become popularly known to mitigate the effects of the Δ(9)-THC. The SCs are dissolved in organic solvents and sprayed in a dry herbal blend. However, little information is reported on active ingredients of SCs as well as the excipients or diluents added to the herbal blend. In this work, the direct infusion electrospray ionization Fourier transform ion cyclotron mass spectrometry technique (ESI-FT-ICR MS) was applied to explore the chemical composition of nine samples of herbal extract blends, where a total of 11 SCs (UR-144, JWH-073, XLR-11, JWH-250, JWH-122, AM-2201, AKB48, JWH-210, JWH-081, MAM-2201 and 5F-AKB48) were identified in the positive ionization mode, ESI(+), and other 44 chemical species (saturated and unsaturated fatty acids, sugars, flavonoids, etc.) were detected in the negative ionization mode, ESI(-). Additionally, CID experiments were performed, and fragmentation pathways were proposed to identify the connectivity of SCs. Thus, the direct infusion ESI-FT-ICR MS technique is a powerful tool in forensic chemistry that enables the rapid and unequivocal way for the determination of molecular formula, the degree of unsaturation (DBE-double bond equivalent) and exact mass (<1ppm) of a total of 55 chemical species without the prior separation step. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

IJUE. Tema 3. Les competències de la Unió Europea

OpenAIRE

Torres Pérez, María

2018-01-01

PowerPoint del Tema 3 de la asignatura "Institucions Jurídiques de la Unió Europea". Curso académico 2017-2018. Tema 3. Les competències de la Unió Europea. 1. L’atribució de competències a la Unió Europea. 2. La delimitació de les competències a la Unió Europea. 3. Els principis que regeixen l’exercici de les competències. 4. L’exercici de les competències de la Unió per “alguns Estats membres”.

Detection of methyl-, dimethyl- and diethylamine using a nitrate-based chemical ionization mass spectrometer

Science.gov (United States)

Jokinen, T.; Smith, J. N.

2016-12-01

New particle formation is one of the main sources of cloud condensation nuclei (CCN) contributing approximately half of the global CCN budget. The initial steps of nucleation have been studied for decades and it is widely accepted that in most places nucleation requires presence of sulphuric acid (SA) and cluster-stabilizing vapours. Recent results from the CLOUD chamber show that only a few pptv levels of dimethylamine (DMA) with SA forms stable clusters at boundary layer conditions. Ambient sulphuric acid is typically measured using nitrate-based chemical ionization mass spectrometers. Unfortunately, because of higher volatilities and stickiness of amines to surfaces, amine measurement techniques suffer from memory effects and high detection limits. Recently it was discovered that DMA can be detected by utilizing nitrate ionization, simultaneously with sulphuric acid measurements. Here we present results of detecting methylamine, dimethylamine and diethylamine using nitrate-based chemical ionization. We conducted a series of measurements with a home-built transverse chemical ionization inlet and a high resolution time-of-flight mass spectrometer (CI-HToF). Amine vapour was produced using permeation tubes. Three stages of dilution were applied at roughly one order-of-magnitude dilution per stage. The diluted flow of selected amine was then introduced to a sample flow rate of 7 slpm, thus achieving a final amine concentration of 10 pptv. All selected amines were detected as clusters with HNO3NO3- and showed linear response with increasing concentrations (0.5-minute integration time). Zero measurements were performed using clean nitrogen gas right after injection of a selected amine. Memory effects were only observed when using high amine concentrations (ppbv levels). Our results indicate that a variety of amines can be detected using nitrate-based chemical ionization mass spectrometers. However, more experiments are required to see if this presented method will be

An NCI perspective on creating sustainable biospecimen resources.

Science.gov (United States)

Vaught, Jimmie; Rogers, Joyce; Myers, Kimberly; Lim, Mark David; Lockhart, Nicole; Moore, Helen; Sawyer, Sherilyn; Furman, Jeffrey L; Compton, Carolyn

2011-01-01

High-quality biospecimens with appropriate clinical annotation are critical in the era of personalized medicine. It is now widely recognized that biospecimen resources need to be developed and operated under established scientific, technical, business, and ethical/legal standards. To date, such standards have not been widely practiced, resulting in variable biospecimen quality that may compromise research efforts. The National Cancer Institute (NCI) Office of Biorepositories and Biospecimen Research (OBBR) was established in 2005 to coordinate NCI's biospecimen resource activities and address those issues that affect access to the high-quality specimens and data necessary for its research enterprises as well as the broader translational research field. OBBR and the NCI Biorepository Coordinating Committee developed NCI's "Best Practices for Biospecimen Resources" after consultation with a broad array of experts. A Biospecimen Research Network was established to fund research to develop additional evidence-based practices. Although these initiatives will improve the overall availability of high-quality specimens and data for cancer research, OBBR has been authorized to implement a national biobanking effort, cancer HUman Biobank (caHUB). caHUB will address systematically the gaps in knowledge needed to improve the state-of-the-science and strengthen the standards for human biobanking. This commentary outlines the progressive efforts by NCI in technical, governance, and economic considerations that will be important as the new caHUB enterprise is undertaken.

Comparison of Electrospray Ionization and Atmospheric Chemical Ionization Coupled with the Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Cholesteryl Esters

Directory of Open Access Journals (Sweden)

Hae-Rim Lee

2015-01-01

Full Text Available The approach of two different ionization techniques including electrospray ionization (ESI and atmospheric pressure chemical ionization (APCI coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS was tested for the analysis of cholesteryl esters (CEs. The retention time (RT, signal intensity, protonated ion, and product ion of CEs were compared between ESI and APCI. RT of CEs from both ionizations decreased with increasing double bonds, while it increased with longer carbon chain length. The ESI process generated strong signal intensity of precursor ions corresponding to [M+Na]+ and [M+NH4]+ regardless of the number of carbon chains and double bonds in CEs. On the other hand, the APCI process produced a protonated ion of CEs [M+H]+ with a weak signal intensity, and it is selectively sensitive to detect precursor ions of CEs with unsaturated fatty acids. The ESI technique proved to be effective in ionizing more kinds of CEs than the APCI technique.

Chemical data on ionizing and non-ionizing angiographic contrast materials

International Nuclear Information System (INIS)

Bonati, F.

1980-01-01

The cardiovascular effects of ionizing and non-ionizing contrast media are compared in experimental animals and in isolated heart preparations. The following parameters were recorded: peripheric arterial diastolic pressure, heart rate, duration of asystolic period, respiratory rate, contractility of the myocardium (dp/dt, LVSP, Vsub(max), EDV, ESV, SV). The observed changes are mainly due to the higher osmotic activity of the contrast media, as similar alterations were recorded after the injection of hyperosmotic glucose solution. It is concluded that administration of non-ionizing contrast media results in significantly less cardiovascular side effects. (L.E.)

Chemical protection and sensitization to ionizing radiation:molecular investigations

International Nuclear Information System (INIS)

Badiello, R.

1980-01-01

Chemical radioprotection and radiosensitization are induced by the presence of certain chemical compounds, which reduce or enhance the effect of ionizing radiation on living organisms. Such substances are either naturally present or may be artificially introduced in the living cells. Chemical radioprotectors are interesting for possible application in the health protection of both professionally exposed workers and patients treated by radiation for diagnostic and thereapeutic purposes. Interest in chemical radiosensitization has increased recently because of its potential application in the radiotherapy of tumours. Both radioprotection and radiosensitization occur by means of complicated mechanisms, which at first correspond to very fast reactions. The mechanism of the interaction between such substances and radiation-induced biological radicals has been investigated by means of pulse radiolysis and rapid mixing techniques. Examples of the application of these techniques are given to illustrate how information has been obtained on the molecular basis of radiation chemical modi-fication at the cellular level. In particular some interactions between model systems of biological interest (DNA, DNA components, enzymes, amino acids, etc.) and sulphur-containing radioprotectors (glutathione, cysteine, etc.) and/or electroaffinic radiosensitizers, are described. (H.K.)

DNA fingerprinting of the NCI-60 cell line panel.

Science.gov (United States)

Lorenzi, Philip L; Reinhold, William C; Varma, Sudhir; Hutchinson, Amy A; Pommier, Yves; Chanock, Stephen J; Weinstein, John N

2009-04-01

The National Cancer Institute's NCI-60 cell line panel, the most extensively characterized set of cells in existence and a public resource, is frequently used as a screening tool for drug discovery. Because many laboratories around the world rely on data from the NCI-60 cells, confirmation of their genetic identities represents an essential step in validating results from them. Given the consequences of cell line contamination or misidentification, quality control measures should routinely include DNA fingerprinting. We have, therefore, used standard DNA microsatellite short tandem repeats to profile the NCI-60, and the resulting DNA fingerprints are provided here as a reference. Consistent with previous reports, the fingerprints suggest that several NCI-60 lines have common origins: the melanoma lines MDA-MB-435, MDA-N, and M14; the central nervous system lines U251 and SNB-19; the ovarian lines OVCAR-8 and OVCAR-8/ADR (also called NCI/ADR); and the prostate lines DU-145, DU-145 (ATCC), and RC0.1. Those lines also show that the ability to connect two fingerprints to the same origin is not affected by stable transfection or by the development of multidrug resistance. As expected, DNA fingerprints were not able to distinguish different tissues-of-origin. The fingerprints serve principally as a barcodes.

NCI Pediatric Preclinical Testing Consortium

Science.gov (United States)

NCI has awarded grants to five research teams to participate in its Pediatric Preclinical Testing Consortium, which is intended to help to prioritize which agents to pursue in pediatric clinical trials.

Chemical systems in aqueous solutions for using in the holographic ionizing radiation

International Nuclear Information System (INIS)

Nicolau-Rebigan, S.

1979-01-01

Some types of chemical systems in aqueous solutions for utilization as active media in holographic ionizing radiation dosimeter are presented. One discussed some advantages of the holographic dosimeter comparatively with another existing types. It is outlined the advantages of using aqueousss solutions as active media in holographic dosimeter. (author)

Direct Laser Ablation and Ionization of Solids for Chemical Analysis by Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Holt, J K; Nelson, E J; Klunder, G L [Forensic Science Center, Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)

2007-04-15

A laser ablation/ionization mass spectrometer system is described for the direct chemical analysis of solids. An Nd:YAG laser is used for ablation and ionization of the sample in a quadrupole ion trap operated in an ion-storage (IS) mode that is coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). Single pulse experiments have demonstrated simultaneous detection of up to 14 elements present in glasses in the ppm range. However, detection of the components has produced non-stoichiometric results due to difference in ionization potentials and fractionation effects. Time-of-flight secondary ionization mass spectrometry (TOF-SIMS) was used to spatially map elemental species on the surface and provide further evidence of fractionation effects. Resolution (m/{delta}m) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

Use of electron ionization and atmospheric pressure chemical ionization in gas chromatography coupled to time-of-flight mass spetrometry for screening and identification of organic pollutants in waters

NARCIS (Netherlands)

Portoles, T.; Mol, J.G.J.; Sancho, J.V.; Hernandez, F.

2014-01-01

A new approach has been developed for multiclass screening of organic contaminants in water based on the use of gas chromatography coupled to hybrid quadrupole high-resolution time-of-flight mass spectrometry with atmospheric pressure chemical ionization (GC–(APCI)QTOF MS). The soft ionization

Quantitative analysis of abused drugs in physiological fluids by gas chromatography/chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Foltz, R.L.

1978-01-01

Methods have been developed for quantitative analysis of commonly abused drugs in physiological fluids using gas chromatography/chemical ionization mass spectrometry. The methods are being evaluated in volunteer analytical and toxicological laboratories, and analytical manuals describing the methods are being prepared. The specific drug and metabolites included in this program are: Δ 9 -tetrahydrocannabinol, methadone, phencyclidine, methaqualone, morphine, amphetamine, methamphetamine, mescaline, 2,5-dimethoxy-4-methyl amphetamine, cocaine, benzoylecgonine, diazepam, and N-desmethyldiazepam. The current analytical methods utilize relatively conventional instrumentation and procedures, and are capable of measuring drug concentrations as low as 1 ng/ml. Various newer techniques such as sample clean-up by high performance liquid chromatography, separation by glass capillary chromatography, and ionization by negative ion chemical ionization are being investigated with respect to their potential for achieving higher sensitivity and specificity, as well as their ability to facilitate simultaneous analysis of more than one drug and metabolite. (Auth.)

Gas chromatography/chemical ionization triple quadrupole mass spectrometry analysis of anabolic steroids: ionization and collision-induced dissociation behavior.

Science.gov (United States)

Polet, Michael; Van Gansbeke, Wim; Van Eenoo, Peter; Deventer, Koen

2016-02-28

The detection of new anabolic steroid metabolites and new designer steroids is a challenging task in doping analysis. Switching from electron ionization gas chromatography triple quadrupole mass spectrometry (GC/EI-MS/MS) to chemical ionization (CI) has proven to be an efficient way to increase the sensitivity of GC/MS/MS analyses and facilitate the detection of anabolic steroids. CI also extends the possibilities of GC/MS/MS analyses as the molecular ion is retained in its protonated form due to the softer ionization. In EI it can be difficult to find previously unknown but expected metabolites due to the low abundance or absence of the molecular ion and the extensive (and to a large extent unpredictable) fragmentation. The main aim of this work was to study the CI and collision-induced dissociation (CID) behavior of a large number of anabolic androgenic steroids (AAS) as their trimethylsilyl derivatives in order to determine correlations between structures and CID fragmentation. Clarification of these correlations is needed for the elucidation of structures of unknown steroids and new metabolites. The ionization and CID behavior of 65 AAS have been studied using GC/CI-MS/MS with ammonia as the reagent gas. Glucuronidated AAS reference standards were first hydrolyzed to obtain their free forms. Afterwards, all the standards were derivatized to their trimethylsilyl forms. Full scan and product ion scan analyses were used to examine the ionization and CID behavior. Full scan and product ion scan analyses revealed clear correlations between AAS structure and the obtained mass spectra. These correlations were confirmed by analysis of multiple hydroxylated, methylated, chlorinated and deuterated analogs. AAS have been divided into three groups according to their ionization behavior and into seven groups according to their CID behavior. Correlations between fragmentation and structure were revealed and fragmentation pathways were postulated. Copyright © 2016 John Wiley

NCI's Role in Immunotherapy Research

Science.gov (United States)

... Reporting & Auditing Grant Transfer Grant Closeout Contracts & Small Business Training Cancer Training at NCI (Intramural) Resources for ... promising immunotherapies to the clinic more efficiently and cost effectively. For ... of the checkpoint inhibitor pembrolizumab in patients with ...

Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

NARCIS (Netherlands)

Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

1991-01-01

Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

Chemical effects and their consequences for individuals occupationally exposed to ionizing radiation

International Nuclear Information System (INIS)

Salvador, C.; Kahl, G.G.; Kühn, P.; Zottis, A.D.; Flôr, R.C.

2017-01-01

By legal determination, workers exposed to ionizing radiation should use individual dosimeters in the most exposed region of the body, designed to estimate the effective dose, as well as radiation protective clothing to minimize occupational exposures. Regarding dosimetry, in most cases it is perceived that the monthly values of exposure are within the limits of normality, however, even being below the limit can not rule out the possibility of damage that the low dose of ionizing radiation can cause. The objective of this article is to highlight the main chemical effects caused by exposure to ionizing radiation, especially biochemical damage in DNA, chromosomal aberrations and the correlation with the exposure of occupationally exposed individuals, as well as individuals from the public. A bibliographic search was carried out in indexed databases from February to April 2017 with the following descriptors: Radiation Ionizing, DNA Damage and Occupational Exposure. In the 'Science Direct' database were found 1205 articles, in the 'Scopus' 19 articles, in the 'Web of Science' 83 articles, in the 'PubMed' 22 articles and in the 'VHL' 60 articles related to the theme. It was concluded that exposure to ionizing radiation can affect the DNA molecule despite its repair mechanisms, which may result in genotoxicity. It has been reported a correlation between occupationally exposed individuals and chromosomal aberrations, demonstrating that even low doses of ionizing radiation can compromise the genetic material integrity of exposed workers, leading to the need for a periodic cytogenetic study for this group of workers

NCI-MATCH Trial Links Targeted Drugs to Mutations

Science.gov (United States)

Investigators for the nationwide trial, NCI-MATCH: Molecular Analysis for Therapy Choice, announced that the trial will seek to determine whether targeted therapies for people whose tumors have specific gene mutations will be effective regardless of their cancer type. NCI-MATCH will incorporate more than 20 different study drugs or drug combinations, each targeting a specific gene mutation, in order to match each patient in the trial with a therapy that targets a molecular abnormality in their tumor.

NCI Takes Back the Defelice Cup at Ninth Annual Golf Tournament | Poster

Science.gov (United States)

By Ashley DeVine, Staff Writer After being down by a point in the morning, NCI reclaimed the Defelice Cup trophy from Leidos Biomedical Research, with a final score of 12 ½ to 11 ½, at the ninth annual Ronald H. Defelice Golf Tournament, held Oct. 13. “The tightest matches in the nine-year history of this cup competition resulted in a narrow victory for NCI and allowed NCI to

Find an NCI-Designated Cancer Center

Science.gov (United States)

Find the locations of NCI-designated cancer centers by area, region, state, or name that includes contact information to help health care providers and cancer patients with referrals to clinical trials.

Comparison of the concepts used to develop and apply occupational exposure limits for ionizing radiation and hazardous chemical substances

International Nuclear Information System (INIS)

Halton, D.M.

1988-01-01

The rationales used by the American Conference of Governmental Industrial Hygienists (AC-GIH) to recommend exposure limits for 10 chemicals were reviewed. The 10 chemicals chosen were known to produce chronic disease after prolonged overexposure in the workplace. The chemicals were toluene diisocyanate, hydrogen fluoride, n-hexane, carbon disulfide, cadmium, inorganic mercury, cobalt, nitroglycerol, silica, and vinyl chloride. The rationales used by the International Commission on Radiological Protection (ICRP) to recommend limits for workplace exposure to ionizing radiation were reviewed. The rationales used in occupational health by ACGIH were then compared with those used by ICRP in health physics. The comparison revealed a significant divergence in the underlying concepts and philosophies of the two approaches. This divergence cannot be solely attributed to differences in scientific knowledge about toxicological and radiological effects. In areas of scientific uncertainty, exposure limits for ionizing radiation are based on worst case or conservative assumptions. This approach favors human safety. Parallel approaches could not be found for any of the 10 chemicals reviewed. Other factors such as the costs incurred by industry in meeting the proposed standards played a more significant role in establishing limits for workplace chemicals than for ionizing radiation

NCI's Transdisciplinary High Performance Scientific Data Platform

Science.gov (United States)

Evans, Ben; Antony, Joseph; Bastrakova, Irina; Car, Nicholas; Cox, Simon; Druken, Kelsey; Evans, Bradley; Fraser, Ryan; Ip, Alex; Kemp, Carina; King, Edward; Minchin, Stuart; Larraondo, Pablo; Pugh, Tim; Richards, Clare; Santana, Fabiana; Smillie, Jon; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

2016-04-01

The Australian National Computational Infrastructure (NCI) manages Earth Systems data collections sourced from several domains and organisations onto a single High Performance Data (HPD) Node to further Australia's national priority research and innovation agenda. The NCI HPD Node has rapidly established its value, currently managing over 10 PBytes of datasets from collections that span a wide range of disciplines including climate, weather, environment, geoscience, geophysics, water resources and social sciences. Importantly, in order to facilitate broad user uptake, maximise reuse and enable transdisciplinary access through software and standardised interfaces, the datasets, associated information systems and processes have been incorporated into the design and operation of a unified platform that NCI has called, the National Environmental Research Data Interoperability Platform (NERDIP). The key goal of the NERDIP is to regularise data access so that it is easily discoverable, interoperable for different domains and enabled for high performance methods. It adopts and implements international standards and data conventions, and promotes scientific integrity within a high performance computing and data analysis environment. NCI has established a rich and flexible computing environment to access to this data, through the NCI supercomputer; a private cloud that supports both domain focused virtual laboratories and in-common interactive analysis interfaces; as well as remotely through scalable data services. Data collections of this importance must be managed with careful consideration of both their current use and the needs of the end-communities, as well as its future potential use, such as transitioning to more advanced software and improved methods. It is therefore critical that the data platform is both well-managed and trusted for stable production use (including transparency and reproducibility), agile enough to incorporate new technological advances and

76 FR 28439 - Submission for OMB Review; Comment Request; NCI Cancer Genetics Services Directory Web-Based...

Science.gov (United States)

2011-05-17

...; Comment Request; NCI Cancer Genetics Services Directory Web-Based Application Form and Update Mailer... currently valid OMB control number. Proposed Collection: Title: NCI Cancer Genetics Services Directory Web... included in the NCI Cancer Genetics Services Directory on NCI's Cancer.gov Web site. The information...

Radioimmunoassay and chemical ionization/mass spectrometry compared for plasma cortisol determination

International Nuclear Information System (INIS)

Lindberg, C.; Johnson, S.; Hedner, P.; Gustafsson, A.

1982-01-01

A method is described for determination of cortisol in plasma and urine, based on chemical ionization/mass spectrometry with deuterium-labeled cortisol as the internal standard. The within-run precision (CV) was 2.5-5.7%, the between-run precision 4.6%. Results by this method were compared with those by a radioimmunological method (RIANEN Cortisol, New England Nuclear) for 395 plasma samples. The latter method gave significantly higher (approx. 25%) cortisol values

Spatially resolved chemical analysis of cicada wings using laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS).

Science.gov (United States)

Román, Jessica K; Walsh, Callee M; Oh, Junho; Dana, Catherine E; Hong, Sungmin; Jo, Kyoo D; Alleyne, Marianne; Miljkovic, Nenad; Cropek, Donald M

2018-03-01

Laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS) is an emerging bioanalytical tool for direct imaging and analysis of biological tissues. Performing ionization in an ambient environment, this technique requires little sample preparation and no additional matrix, and can be performed on natural, uneven surfaces. When combined with optical microscopy, the investigation of biological samples by LAESI allows for spatially resolved compositional analysis. We demonstrate here the applicability of LAESI-IMS for the chemical analysis of thin, desiccated biological samples, specifically Neotibicen pruinosus cicada wings. Positive-ion LAESI-IMS accurate ion-map data was acquired from several wing cells and superimposed onto optical images allowing for compositional comparisons across areas of the wing. Various putative chemical identifications were made indicating the presence of hydrocarbons, lipids/esters, amines/amides, and sulfonated/phosphorylated compounds. With the spatial resolution capability, surprising chemical distribution patterns were observed across the cicada wing, which may assist in correlating trends in surface properties with chemical distribution. Observed ions were either (1) equally dispersed across the wing, (2) more concentrated closer to the body of the insect (proximal end), or (3) more concentrated toward the tip of the wing (distal end). These findings demonstrate LAESI-IMS as a tool for the acquisition of spatially resolved chemical information from fragile, dried insect wings. This LAESI-IMS technique has important implications for the study of functional biomaterials, where understanding the correlation between chemical composition, physical structure, and biological function is critical. Graphical abstract Positive-ion laser-ablation electrospray ionization mass spectrometry coupled with optical imaging provides a powerful tool for the spatially resolved chemical analysis of cicada wings.

Dosimetry of ionizing radiation

International Nuclear Information System (INIS)

Musilek, L.; Seda, J.; Trousil, J.

1992-01-01

The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

Decomposition of halogenated organic chemicals in ionic liquid by ionizing radiation

International Nuclear Information System (INIS)

Kimura, A.; Taguchi, M.; Kojima, T.; Nagaishi, R.; Hiratsuka, H.

2006-01-01

Introduction: Halogenated organic chemicals such as polychlorodibenzo-p-dioxin, polychlorobiphenyls and hexachlorobenzene are widely spread in water environment. These pollutants are persistent against advanced oxidation treatments such as ozone/UV, ozone/hydrogen peroxide, ionizing radiation and photocatalysts. The ionizing radiation, however, can also produce homogeneously and quantitatively reducing species in water. On the other hand, room temperature ionic liquids (RTILs) have unique properties such as nonflammable, high polarity, low melting point, hydrophobicity and wide electrochemical window. The combined method of reduction by ionizing radiation and RTILs is investigated as a new environmental conservation technology. Experimental: Chlorophenol (CP) is selected as model chemicals having the main frame of halogenated organic chemicals. Each o - , m - and p-CP were irradiated with 60 Co γ-ray in each diethylmethyl(2-methoxy-ethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEMMA- TFSI), diethylmethyl(2-methoxyethyl)-ammonium tetrafluoroborate (DEMMA-BF4), methanol and ethanol as solvent. Decomposition of CP and formation of irradiation products were studied using HPLC, LC-MS and ion chromatography. Results and discussion: Concentration of CP in each solution decreased as a function of dose. G-value was estimated from the slope at the primary stage of the decomposition curve. The G(-CP) and G(Phenol) were shown in Table 1. G(-CP) in the aliphatic alcohols was 0.21 to 0.37, which is lower than G-value of reducing species in the alcohols, e.g. G=1.0 to 1.5 for solvated electron. Since the rate constant for reaction of CP with hydrated electron is 1.3 x 10 9 mol -1 ·dm 3 ·s -1 , the reverse reaction is considered to attribute. G(-CP) in DEMMA-TFSI or DEMMA-BF4 was about 2 to 3 times higher than that in each alcohol. Lifetime of the reducing species in RTILs would be longer than that in each alcohol. G(-CP) in DEMMA-TFSI decreased by adding acetone or oxygen

DISSENYAR EXPERIÈNCIES AMB VALOR TURÍSTIC: PAISATGES URBANS

Directory of Open Access Journals (Sweden)

Francesc Fusté

2015-10-01

Full Text Available Aquest article tracta sobre les possibilitats que la creació d’experiències té en relació al desenvolupament empresarial i regional, gràcies a la tematització del sector turístic i la modificació intencional de l’entorn, tant cultural com natural. El paisatge caracteritza els espais en funció de la seva configuració territorial i també arquitectònica i urbana. Les estructures arquitectòniques, els esdeveniments i les activitats que impliquen la participació activa dels usuaris són la clau de l’èxit del disseny de les experiències amb un valor afegit, on les noves tecnologies ajuden a emfatitzar-ne l’impacte. Sigui com sigui, convertir els llocs en experiències tant pels residents com pels visitants.

Application of Ni-63 photo and corona discharge ionization for the analysis of chemical warfare agents and toxic wastes

Science.gov (United States)

Stach, J.; Adler, J.; Brodacki, M.; Doring, H.-R.

1995-01-01

Over the past decade, advances in instrumental design and refinements in the understanding of ion molecule reactions at atmospheric pressure enabled the application of Ion Mobility Spectrometry (IMS) as a simple inexpensive and sensitive analytical method for the detection of organic trace compounds. Positive and negative gas-phase ions for ion mobility spectrometry have been produced by a variety of methods, including photo-ionization, laser multi photon ionization, surface ionization, corona discharge ionization. The most common ion source used in ion mobility spectrometry is a radioactive Ni-63 foil which is favored due to simplicity, stability, convenience, and high selectivity. If reactant ions like (H2O(n)H)(+) or (H2O(n)O2)(-) dominate in the reaction region, nearly all kinds of compounds with a given proton or electron affinity; are ionized. However, the radioactivity of the Ni-63 foil is one disadvantage of this ion source that stimulates the development and application of other ionization techniques. In this paper, we report analyses of old chemical warfare agents and toxic wastes using Bruker RAID ion mobility spectrometers. Due to the modular construction of the measuring cell, the spectrometers can be equipped with different ion sources. The combined use of Ni-63, photo- and corona discharge ionization allows the identification of different classes of chemical compounds and yields in most cases comparable results.

NCI Scientists Awarded National Medal of Technology and Innovation by President Obama | Poster

Science.gov (United States)

Two NCI scientists received the National Medal of Technology and Innovation, the nation’s highest honor for technological achievement. The award was announced by President Obama in October. The honorees, John Schiller, Ph.D., Laboratory of Cellular Oncology (LCO), Center for Cancer Research, NCI, and Douglas Lowy, M.D., also from LCO and NCI deputy director, received their medals at a White House ceremony on Nov. 20.

Defence biochemical mechanisms of the organisms against chemical pollution and ionizing radiations

International Nuclear Information System (INIS)

Olinescu, Radu

2001-01-01

Acute exposure to high concentrations / doses of chemical pollutants and ionizing radiation usually kills giving no chance for survival, if not immediately, than later followed by specific diseases. Fortunately, this acute exposure is accidental, but chronic, low level exposure is also damaging. The involvement of pollution, especially of chemically produced, one in the etiology of several diseases is still under intensive research. Compared to other kinds of pollution (radioactive, microbiological), the chemical one seldom kills suddenly; it acts slowly, silently, by accumulation into the tissues, eventually inducing a failure of certain organ. The body is continuously adapting to low level concentrations of chemicals from environment until a certain threshold. All organisms, including humans, have a limited capacity of resisting the effects of various types of pollutants. Extensive laboratory research, demonstrated that most of damaging organic pollutants cause the formation of free radicals when they penetrate into the body and are metabolized. Free radicals are very reactive and are known to damage tissues with potentially fatal results. Substantial experimental evidence in recent years has demonstrated that all organisms are endowed with versatile, efficient antioxidant systems, that provide protection against the formation or effects of free radicals. However, the antioxidant systems are limited and when their capacity of protection is exceeded, injury resulting in illness or death occurs. In most cases, the harmful effects of chemicals on organisms depend on the biotransformation step, where free radicals are produced as byproducts of the metabolic reactions. The damaging effects of chemical pollutants are mostly restricted to an important organ depending on the way of penetration, nature of the compound and concentration. The organisms possess specific and nonspecific defense systems, which act from the exposure step, with attempt to block the entry of

Selected Publications by the NCI Director

Science.gov (United States)

Dr. Norman Sharpless's written work on cancer research appears in many leading scientific journals, as well as a variety of other publications. This page lists some of the articles published by Dr. Sharpless since becoming NCI director.

Analysis of insect triacylglycerols using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

Czech Academy of Sciences Publication Activity Database

Kofroňová, Edita; Cvačka, Josef; Jiroš, Pavel; Sýkora, D.; Valterová, Irena

2009-01-01

Roč. 111, č. 5 (2009), s. 519-525 ISSN 1438-7697 R&D Projects: GA AV ČR IAA4055403; GA MŠk 2B06007 Institutional research plan: CEZ:AV0Z40550506 Keywords : atmospheric pressure chemical ionization * bumblebees * fat body * NARP-HPLC Subject RIV: CC - Organic Chemistry Impact factor: 1.831, year: 2009

Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

CERN Document Server

Rondo, L.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

2016-01-01

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosolnucleation. Based on quantum chemical calculations it has been suggested that the quantitative detectionof gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased inthe presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was setup at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection ofH2SO4in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time inthe CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF(Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutralsulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presenceof dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS...

Invention Development Program Helps Nurture NCI at Frederick Technologies | Poster

Science.gov (United States)

The Invention Development Fund (IDF) was piloted by the Technology Transfer Center (TTC) in 2014 to facilitate the commercial development of NCI technologies. The IDF received a second round of funding from the NCI Office of the Director and the Office of Budget and Management to establish the Invention Development Program (IDP) for fiscal year 2016. The IDP is using these funds to help advance a second set of inventions.

Report on NCI symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. II. Cellular and animal models

International Nuclear Information System (INIS)

Fry, R.J.M.

1984-01-01

The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could be demonstrated after exposure to low-LET radiation but not after exposure to chemical carcinogens

Report on NCI symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. II. Cellular and animal models

Energy Technology Data Exchange (ETDEWEB)

Fry, R.J.M.

1984-01-01

The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could be demonstrated after exposure to low-LET radiation but not after exposure to chemical carcinogens.

Photochemistry of limonene secondary organic aerosol studied with chemical ionization mass spectrometry

Science.gov (United States)

Pan, Xiang

Limonene is one of the most abundant monoterpenes in the atmosphere. Limonene easily reacts with gas-phase oxidants in air such as NO3, ozone and OH. Secondary organic aerosol (SOA) is formed when low vapor pressure products condense into particles. Chemicals in SOA particles can undergo further reactions with oxidants and with solar radiation that significantly change SOA composition over the course of several days. The goal of this work was to characterize radiation induced reaction in SOA. To perform experiments, we have designed and constructed an Atmospheric Pressure Chemical Ionization Mass Spectrometer (APCIMS) coupled to a photochemical cell containing SOA samples. In APCIMS, (H2O)nH 3O+ clusters are generated in a 63Ni source and react with gaseous organic analytes. Most organic chemicals are not fragmented by the ionization process. We have focused our attention on limonene SOA prepared in two different ways. The first type of SOA is produced by oxidation of limonene by ozone; and the second type of SOA is formed by the NO3-induced oxidation of limonene. They model the SOA formed under daytime and nighttime conditions, respectively. Ozone initiated oxidation is the most important chemical sink for limonene both indoors, where it is used for cleaning purposes, and outdoors. Terpenes are primarily oxidized by reactions with NO3 at night time. We generated limonene SOA under different ozone and limonene concentrations. The resulting SOA samples were exposed to wavelength-tunable radiation in the UV-Visible range between 270 nm and 630 nm. The results show that the photodegradation rates strongly depend on radiation wavelengths. Gas phase photodegradation products such as acetone, formaldehyde, acetaldehyde, and acetic acid were shown to have different production rates for SOA formed in different concentration conditions. Even for SOA prepared under the lowest concentrations, the SOA photodegradation was efficient. The conclusion is that exposure of SOA to

About TTC | NCI Technology Transfer Center | TTC

Science.gov (United States)

The TTC facilitates licensing and co-development partnerships between biomedical industry, academia, and government agencies and the research laboratories of the NCI and nine other institutes and centers of NIH.

Life Outside NCI | Cancer Prevention Fellowship Program

Science.gov (United States)

The CPFP Office is located at the NCI facilities in Rockville, Maryland, near the Nation’s Capital. With the convenient Metro subway reaching throughout the metropolitan area, transportation is within easy reach.

Influence of soil pH on the sorption of ionizable chemicals: modeling advances.

Science.gov (United States)

Franco, Antonio; Fu, Wenjing; Trapp, Stefan

2009-03-01

The soil-water distribution coefficient of ionizable chemicals (K(d)) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K(d) values normalized to organic carbon (K(OC)) from the literature, a method was developed to estimate the K(OC) of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pK(a)) and the octanol-water partition coefficient of the neutral molecule (log P(n)). Probably because of the lower pH near the organic colloid-water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals.

At NCI, Supporting the Best Science

Science.gov (United States)

Yesterday, at the AACR annual meeting, Dr. Doug Lowy spoke directly to the research community about his goals as NCI Acting Director. Dr. Lowy said that he plans to continue many of the programs launched by his predecessor, Dr. Harold Varmus, and to sharp

Atmospheric Pressure Chemical Ionization Sources Used in The Detection of Explosives by Ion Mobility Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Waltman, Melanie J. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

2010-05-01

Explosives detection is a necessary and wide spread field of research. From large shipping containers to airline luggage, numerous items are tested for explosives every day. In the area of trace explosives detection, ion mobility spectrometry (IMS) is the technique employed most often because it is a quick, simple, and accurate way to test many items in a short amount of time. Detection by IMS is based on the difference in drift times of product ions through the drift region of an IMS instrument. The product ions are created when the explosive compounds, introduced to the instrument, are chemically ionized through interactions with the reactant ions. The identity of the reactant ions determines the outcomes of the ionization process. This research investigated the reactant ions created by various ionization sources and looked into ways to manipulate the chemistry occurring in the sources.

Robert Wiltrout Says Goodbye to NCI in 2015 | Poster

Science.gov (United States)

After 34 years at NCI, Robert Wiltrout, Ph.D., said he is looking forward to trading his I-270 commute for another type of commute: exploring the waterways of Maryland, Alaska, and Wyoming to fulfill his love of fishing. Wiltrout officially retired as director of the NCI Center for Cancer Research (CCR) on July 2 of last year. Throughout his college academic career, Wiltrout had an interest in science, but it was not until he was working on a research project for his master’s degree that he considered a career in scientific research.

NCI and the Precision Medicine Initiative®

Science.gov (United States)

NCI's activities related to precision medicine focuses on new and expanded precision medicine clinical trials; mechanisms to overcome drug resistance to cancer treatments; and developing a shared digital repository of precision medicine trials data.

Cooperative biological effects between ionizing radiation and other physical and chemical agents.

Science.gov (United States)

Manti, Lorenzo; D'Arco, Annalisa

2010-01-01

Exposure to ionizing radiation (IR), at environmentally and therapeutically relevant doses or as a result of diagnostics or accidents, causes cyto- and genotoxic damage. However, exposure to IR alone is a rare event as it occurs in spatial and temporal combination with several physico-chemical agents. Some of these are of known noxiousness, as is the case with chemical compounds at high dose, hence additive/synergistic effects can be expected or have been demonstrated. Conversely, the cellular toxicity of other agents, such as non-ionizing electromagnetic fields (EMFs), is only presumed and their short- and long-term cooperation on IR-induced damage remains undetermined. In this review, we shall examine evidence in support of the interplay between spatially and/or temporally related environmentally relevant stressors. In vitro or animal-based studies as well as epidemiological surveys have generally examined the combined action of no more than a couple of known or potentially DNA-damaging agents. Moreover, most existing research mainly focused on short-term effects of combined exposures. Hence, it is important that quantitative research addresses the issue of the possible cooperation between chronic exposure to environmental trace contaminants and exposure to EMFs, examining not only the modulation of damage acutely induced by IR but also long-term genome stability. 2010 Elsevier B.V. All rights reserved.

Human Monoclonal Antibodies Targeting Glypican-2 in Neuroblastoma | NCI Technology Transfer Center | TTC

Science.gov (United States)

Researchers at the National Cancer Institute’s Laboratory of Molecular Biology (NCI LMB) have developed and isolated several single domain monoclonal human antibodies against GPC2. NCI seeks parties interested in licensing or co-developing GPC2 antibodies and/or conjugates.

Biological Effects of Ionizing Radiation

Science.gov (United States)

Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

1952-04-07

This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

Les competències. La doctrina del Tribunal sobre la definició de les competències. Les competències exclusives, les compartides i les executives. - Las competencias. La doctrina del Tribunal sobre la definición de las competencias. Competencias exclusivas, compartidas y ejecutivas.

Directory of Open Access Journals (Sweden)

Ramon Riu

2010-07-01

Full Text Available La doctrina de la Sentència 31/2010 sobre la definició estatutària de les categories competencials (251-257 Mercè Barceló i SerramaleraLa doctrina del Tribunal Constitucional sobre la definició de competències. Les competències exclusives, les compartides i les executives (258-261Antoni Bayona RocamoraLa doctrina de la Sentència 31/2010 sobre les competències executives (Xavier Bernadí GilLa doctrina del Tribunal sobre la definició de les competències. Les ompetències exclusives, les compartides i les executives (270-276Marc Carrillo LópezEls efectes de la Sentència sobre la definició estatutària de les competències: la «devaluació» jurídica dels estatuts d’autonomia (277-281Mercè Corretja TorrensLes categories funcionals de competències a l’Estatut d’autonomia de Catalunya. Comentaris a la Sentència 31/2010 (282-287Ramon Riu FortunyTipologia de les competències. El seu abast funcional: els articles 110 a 112 (288-294Joaquín Tornos Massostenella e no enmendalla (262-269 La doctrina de la Sentencia 31/2010 sobre la definición estatutaria de las categorías competenciales (251-257Mercè Barceló i SerramaleraLa doctrina del Tribunal Constitucional sobre la definición de competencias. Las competencias exclusivas, las compartidas y las ejecutivas (258-261Antoni Bayona RocamoraLa doctrina de la Sentencia 31/2010 sobre las competencias ejecutivas (sostenella e no enmendalla (262-270 Xavier Bernadí GilLa doctrina del Tribunal sobre la definición de las competencias. Las competencias exclusivas, las compartidas y las ejecutivas (271-277Marc Carrillo LópezLos efectos de la Sentencia sobre la definición estatutaria de las competencias:la «devaluación» jurídica de los estatutos de autonomía (278-283Mercè Corretja TorrensLas categorías funcionales de competencias en el Estatuto de Autonomía de Cataluña. Comentarios a la Sentencia 31/2010 (284-289Ramon Riu FortunyTipología de las competencias. Su alcance

Ambient ionization mass spectrometry: A tutorial

Energy Technology Data Exchange (ETDEWEB)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

2011-09-19

Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Ambient ionization mass spectrometry: A tutorial

International Nuclear Information System (INIS)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu; Shiea, Jentaie

2011-01-01

Highlights: → Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. → We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. → The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Analysis of Nitro-aromatic and Nitramine Explosives by Atmospheric Pressure Chemical Ionization / High Performance Liquid Chromatography / Mass Spectrometry / Mass Spectrometry

International Nuclear Information System (INIS)

Hicks, B.J.; Han, W.; Robben, J.R.

2009-01-01

This procedure is capable of separating and quantifying twenty-nine high explosives and internal surrogates with a single injection. After the initial preparation step, the sample is introduced to the high performance liquid chromatograph for target separation, ionized by atmospheric pressure chemical ionization and the explosives of interest are isolated / quantified by mass spectrometry / mass spectrometry. Concentrations of the target explosives are measured relative to the response of both internal and external standard concentrations. A C-18 reverse phase high performance liquid chromatograph column is used for separation. Ionization is performed using both positive and negative atmospheric pressure chemical ionization resulting in a molecular ion with little fragmentation. These ions are isolated at the first quadrupole of the mass spectrometer, dissociated by collision with argon in the collision cell and the resulting daughter ions are isolated at the second quadrupole. These daughter ions then reach the detector where they are quantified. To date this procedure represents the most thorough high performance liquid chromatography / mass spectrometry / mass spectrometry explosives analysis available in the environmental chemistry market. (authors)

NIH and NCI grant-related changes during fiscal years 2014 and 2015

Science.gov (United States)

Wong, Rosemary S. L.

2015-03-01

The 2014 fiscal year (FY) continued to be a challenging one for all federal agencies despite the many Congressional strategies proposed to address the U.S. budget deficit. The Bipartisan Budget Act of 2013 passed by the House and Senate in December 2013 approved a two-year spending bill which cancelled the FY2014 and FY2015 required sequestration cuts (i.e., 4-5% National Institute of Health (NIH)/National Cancer Institute (NCI) budget reduction initiated on March 1, 2013), but extended the sequestration period through FY2023. This bill passage helped minimize any further budget reductions and resulted in a final FY2014 NIH budget of 29.9 billion and a NCI budget of 4.9 billion. Both NIH and NCI worked hard to maintain awarding the same number of NIH/NCI investigator-initiated R01 and exploratory R21 grants funded in FY2014 and similar to the level seen in FY2013 and previous years (see Tables 1 and 2). Since Congress only recently passed the 2015 spending bill in December 16, 2014, the final NIH and NCI budget appropriations for FY2015 remains unknown at this time and most likely will be similar to the FY2014 budget level. The NCI overall success and funding rates for unsolicited investigator-initiated R01 applications remained at 15%, while the success rate for exploratory R21 applications was 12% in FY2014 with similar rates seen in FY2013 (see Tables 1 and 2). The success rate for biomedical research applications in the Photodynamic Therapy and laser research field will be provided for the past few years. NIH provides numerous resources to help inform the extramural biomedical research community of new and current grant applicants about new grant policy changes and the grant submission and review processes.

NCI International EBV-Gastric Cancer Consortium

Science.gov (United States)

A collaboration among NCI and extramural investigators, established by DCEG in 2006, that utilizes data and biospecimens from completed and ongoing case series and observational studies of gastric cancer to replicate and extend findings from previous studies hindered by small numbers of EBV-positive cases, and to stimulate multidisciplinary research in this area.

Induction of somatic mutations in ornamental plants by ionizing radiations and chemical mutagens

International Nuclear Information System (INIS)

Desai, B.M.; Abraham, V.

1980-01-01

Improvement in some ornamental plants through induction of somatic mutations by ionizing radiations and chemical mutagens viz. colchicine, EMS and DS has been attempted. Mutants of high ornamental value have been evolved, isolated and multiplied in canna, perennial portulaca, tuberose, bougainvillea, hibiscus, daisy, lilies. These pertain to changes in colour, shape and size of flower and foliage. Procedural details on induction, isolation, stabilisation of the mutants and description of the new characteristics are presented. (author)

High molecular weight non-polar hydrocarbons as pure model substances and in motor oil samples can be ionized without fragmentation by atmospheric pressure chemical ionization mass spectrometry.

Science.gov (United States)

Hourani, Nadim; Kuhnert, Nikolai

2012-10-15

High molecular weight non-polar hydrocarbons are still difficult to detect by mass spectrometry. Although several studies have targeted this problem, lack of good self-ionization has limited the ability of mass spectrometry to examine these hydrocarbons. Failure to control ion generation in the atmospheric pressure chemical ionization (APCI) source hampers the detection of intact stable gas-phase ions of non-polar hydrocarbon in mass spectrometry. Seventeen non-volatile non-polar hydrocarbons, reported to be difficult to ionize, were examined by an optimized APCI methodology using nitrogen as the reagent gas. All these analytes were successfully ionized as abundant and intact stable [M-H](+) ions without the use of any derivatization or adduct chemistry and without significant fragmentation. Application of the method to real-life hydrocarbon mixtures like light shredder waste and car motor oil was demonstrated. Despite numerous reports to the contrary, it is possible to ionize high molecular weight non-polar hydrocarbons by APCI, omitting the use of additives. This finding represents a significant step towards extending the applicability of mass spectrometry to non-polar hydrocarbon analyses in crude oil, petrochemical products, waste or food. Copyright © 2012 John Wiley & Sons, Ltd.

Spatial patterns of FUS-immunoreactive neuronal cytoplasmic inclusions (NCI) in neuronal intermediate filament inclusion disease (NIFID).

Science.gov (United States)

Armstrong, Richard A; Gearing, Marla; Bigio, Eileen H; Cruz-Sanchez, Felix F; Duyckaerts, Charles; Mackenzie, Ian R A; Perry, Robert H; Skullerud, Kari; Yokoo, Hideaki; Cairns, Nigel J

2011-11-01

Neuronal intermediate filament inclusion disease (NIFID), a rare form of frontotemporal lobar degeneration (FTLD), is characterized neuropathologically by focal atrophy of the frontal and temporal lobes, neuronal loss, gliosis, and neuronal cytoplasmic inclusions (NCI) containing epitopes of ubiquitin and neuronal intermediate filament (IF) proteins. Recently, the 'fused in sarcoma' (FUS) protein (encoded by the FUS gene) has been shown to be a component of the inclusions of NIFID. To further characterize FUS proteinopathy in NIFID, we studied the spatial patterns of the FUS-immunoreactive NCI in frontal and temporal cortex of 10 cases. In the cerebral cortex, sectors CA1/2 of the hippocampus, and the dentate gyrus (DG), the FUS-immunoreactive NCI were frequently clustered and the clusters were regularly distributed parallel to the tissue boundary. In a proportion of cortical gyri, cluster size of the NCI approximated to those of the columns of cells was associated with the cortico-cortical projections. There were no significant differences in the frequency of different types of spatial patterns with disease duration or disease stage. Clusters of NCI in the upper and lower cortex were significantly larger using FUS compared with phosphorylated, neurofilament heavy polypeptide (NEFH) or α-internexin (INA) immunohistochemistry (IHC). We concluded: (1) FUS-immunoreactive NCI exhibit similar spatial patterns to analogous inclusions in the tauopathies and synucleinopathies, (2) clusters of FUS-immunoreactive NCI are larger than those revealed by NEFH or ΙΝΑ, and (3) the spatial patterns of the FUS-immunoreactive NCI suggest the degeneration of the cortico-cortical projections in NIFID.

College Graduate with NCI Internship Gains Experience, Carries Chemistry into Medicine | Poster

Science.gov (United States)

For Jennifer Marshall, the skills learned through an internship at the National Cancer Institute (NCI) at Frederick have prepared her for the next step of her life—medical school. Marshall, who will be attending the West Virginia University School of Medicine in the fall, spent three summers in NCI at Frederick’s Summer Internship Program expanding her love and passion for

Ionization effects in electronic inner-shells of ionized atoms

International Nuclear Information System (INIS)

Shchornak, G.

1983-01-01

A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Smith, JN [Univ. of California, Irvine, CA (United States)

2016-04-01

The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

Modelling the Fate of Ionizable Trace Organic Chemicals from Consumption to Food Crops

DEFF Research Database (Denmark)

Polesel, Fabio; Plósz, Benedek G.; Trapp, Stefan

In this study, we developed and applied a simulation tool to comprehensively predict the fate of three ionizable trace chemicals (triclosan—TCS, furosemide—FUR, ciprofloxacin—CIP) from human consumption/excretion up to the accumulation in wheat, following application of sewage sludge or irrigation...... with river water. Highest translocation to wheat (4.3 μg kgDW-1 in grain) was calculated for FUR, being more significant with irrigation (>45% of emission to soil) than with sludge application (

Comparative experimental study of cancer induced by ionizing radiations or by chemical carcinogens

International Nuclear Information System (INIS)

Lafuma, J.

1983-01-01

Animal experiments have contributed to specify a number of parameters used in setting human safety limits for ionizing radiation. In the same way, comparisons have been made between cancers induced in man and in animals in well-defined conditions. In order to use the same experimental data for chemical carcinogens, the mechanisms of carcinogenesis should be the same, i.e. additivity of responses instead of synergy of effects, which requires the development of a new experimental method [fr

Enhanced signal generation for use in the analysis of synthetic pyrethroids using chemical ionization tandem quadrupole ion trap mass spectrometry.

Science.gov (United States)

Sichilongo, Kwenga

2004-12-01

Synthetic pyrethroids fragment extensively under electron ionization (EI) conditions to give low mass ions, most of them with the same m/z ratios. This fragmentation is primarily due to the labile ester linkage found in these compounds. In this research we established the best gas chromatography (GC) conditions in the EI mode that served as a benchmark in the development of a chemical ionization (CI) protocol for ten selected synthetic pyrethroids. Based on proton affinity data, several reagent gases were evaluated in the positive CI ionization mode. Methanol was found to produce higher average ion counts relative to the other gases evaluated, which led to the development of an optimized method consisting of selective ejection chemical ionization (SECI) and MS/MS. Standard stainless steel ion trap electrodes produced significant degradation of chromatographic performance on late eluting compounds, which was attributed to electrode surface chemistry. A dramatic improvement in signal-to-noise (S/N) ratios was observed when the chromatographically inert Silcosteel coated electrodes were used. The resulting method, that has significant S/N ratio improvements resulting from a combination of septum programmable injections (SPI), optimized CI and inert Silcosteel-coated electrodes, was used to determine instrument detection limits.

Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

Science.gov (United States)

Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

2014-05-06

A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.

The chemical basis of DNA damage by the direct pathway of ionizing radiation

International Nuclear Information System (INIS)

Sharma, Kiran Kumar K.

2013-01-01

Free radicals in living system has been implicated as playing a major role in the etiology of variety of diseases. The mechanism of free radicals in vivo involves predominantly the reaction with the DNA, producing different types of damage to the DNA. These lesions induced to the DNA could lead to mutation and even cell death. Radiolysis techniques, which uses ionizing radiation has proven to be one of the most advanced and excellent tool for studying the free radical reaction mechanisms as it can produce a host of well characterized free radicals. The effects of ionizing radiation on DNA have been studied for many years. Ionizing radiation interacts with DNA in vivo by two pathways, direct and indirect. The indirect accounts for 50-60% while the direct effect accounts for 40-50%. The chemical mechanism of the former reaction arising mainly from the reactive species produced by radiolysis of water has been extensively studied, however with respect to the later pathway, which creates holes and electrons to the DNA molecule using DNA films and crystals is an active area of research as both the pathways plays important roles in DNA damage in vivo particularly in chromosomal DNA which are tightly bound with histones and compartmentalized

Vaccine for BK Polyomavirus-associated Infections in Transplant Recipients | NCI Technology Transfer Center | TTC

Science.gov (United States)

NCI researches identified a BK polyomavirus (BKV) virulent strain that causes chronic urinary tract infections, and the development of vaccine and therapeutic methods that would block BKV pathogenesis. The NCI Laboratory of Cellular Oncology, seek parties to license or co-develop this technology.

Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

Science.gov (United States)

Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

2017-07-01

Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

Influence of soil pH on the sorption of ionizable chemicals

DEFF Research Database (Denmark)

Franco, Antonio; Fu, Wenjing; Trapp, Stefan

2009-01-01

, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of p......The soil-water distribution coefficient of ionizable chemicals (K-d) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K-d values normalized to organic carbon (K-OC) from the literature, a method was developed to estimate the K-OC of monovalent organic acids...

From consumption to harvest: Environmental fate prediction of excreted ionizable trace organic chemicals

DEFF Research Database (Denmark)

Polesel, Fabio; Plósz, Benedek G.; Trapp, Stefan

2015-01-01

Excreted trace organic chemicals, e.g., pharmaceuticals and biocides, typically undergo incomplete elimination in municipal wastewater treatment plants (WWTPs) and are released to surface water via treated effluents and to agricultural soils through sludge amendment and/or irrigation with freshwa......Excreted trace organic chemicals, e.g., pharmaceuticals and biocides, typically undergo incomplete elimination in municipal wastewater treatment plants (WWTPs) and are released to surface water via treated effluents and to agricultural soils through sludge amendment and/or irrigation...... with freshwater or reclaimed wastewater. Recent research has shown the tendency for these substances to accumulate in food crops. In this study, we developed and applied a simulation tool to predict the fate of three ionizable trace chemicals (triclosan-TCS, furosemide-FUR, ciprofloxacin-CIP) from human...... and a recently developed dynamic soil-plant uptake model. The simulation tool was tested using country-specific (e.g., consumption/emission rates, precipitation and temperature) input data. A Monte Carlo-based approach was adopted to account for the uncertainty associated to physico-chemical and biokinetic model...

Coupling an electrospray source and a solids probe/chemical ionization source to a selected ion flow tube apparatus

International Nuclear Information System (INIS)

Melko, Joshua J.; Ard, Shaun G.; Shuman, Nicholas S.; Viggiano, Albert A.; Pedder, Randall E.; Taormina, Christopher R.

2015-01-01

A new ion source region has been constructed and attached to a variable temperature selected ion flow tube. The source features the capabilities of electron impact, chemical ionization, a solids probe, and electrospray ionization. The performance of the instrument is demonstrated through a series of reactions from ions created in each of the new source regions. The chemical ionization source is able to create H 3 O + , but not as efficiently as similar sources with larger apertures. The ability of this source to support a solids probe, however, greatly expands our capabilities. A variety of rhenium cations and dications are created from the solids probe in sufficient abundance to study in the flow tube. The reaction of Re + with O 2 proceeds with a rate constant that agrees with the literature measurements, while the reaction of Re 2 2+ is found to charge transfer with O 2 at about 60% of the collision rate; we have also performed calculations that support the charge transfer pathway. The electrospray source is used to create Ba + , which is reacted with N 2 O to create BaO + , and we find a rate constant that agrees with the literature

The NCI Digital Divide Pilot Projects: implications for cancer education.

Science.gov (United States)

Kreps, Gary L; Gustafson, David; Salovey, Peter; Perocchia, Rosemarie Slevin; Wilbright, Wayne; Bright, Mary Anne; Muha, Cathy

2007-01-01

The National Cancer Institute (NCI) supported four innovative demonstration research projects, "The Digital Divide Pilot Projects," to test new strategies for disseminating health information via computer to vulnerable consumers. These projects involved active research collaborations between the NCI's Cancer Information Service (CIS) and regional cancer control researchers to field test new approaches for enhancing cancer communication in vulnerable communities. The projects were able to use computers to successfully disseminate relevant cancer information to vulnerable populations. These demonstration research projects suggested effective new strategies for using communication technologies to educate underserved populations about cancer prevention, control, and care.

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

Science.gov (United States)

Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

2016-08-01

The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ.

Published Research - NCI Alliance for Nanotechnology in Cancer

Science.gov (United States)

The NCI Alliance for Nanotechnology in Cancer has published much exciting and impactful research over the years. Find here a list of all of these listed in PubMed and others across the field of Cancer Nanotechnology.

A rapid novel derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography electron ionization and chemical ionization mass spectrometric analysis.

Science.gov (United States)

Dasgupta, A; Spies, J

1998-05-01

Amphetamine and methamphetamine are commonly abused central nervous system stimulants. We describe a rapid new derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography-mass spectrometric analysis. Amphetamine and methamphetamine, along with N-propyl amphetamine (internal standard), were extracted from urine using 1-chlorobutane. The derivatization with 2,2,2-trichloroethyl chloroformate can be achieved at room temperature in 10 minutes. The electron ionization mass spectrum of amphetamine 2,2,2-trichloroethyl carbamate showed two weak molecular ions at m/z 309 and 311, but showed diagnostic strong peaks at m/z 218, 220, and 222. In contrast, chemical ionization of the mass spectrum of amphetamine 2,2,2-trichloroethyl carbamate showed strong (M + 1) ions at m/z 310 and 312 and other strong diagnostic peaks at m/z 274 and 276. The major advantages of this derivative are the presence of a diagnostic cluster of peaks due to the isotopic effect of three chlorine atoms (isotopes 35 and 37) in the derivatized molecule and the relative ease of its preparation. We also observed strong molecular ions for derivatized methamphetamine in the chemical ionization mass spectrum, but the molecular ions were very weak in the electron ionization mass spectrum. We used the scan mode of mass spectrometry in all analyses. When using a urine standard containing 1,000 ng/mL of amphetamine (a 7.4-micromol/L concentration) and methamphetamine (a 6.7-micromol/L concentration), the within-run precisions were 4.8% for amphetamine and 3.6% for methamphetamine. The corresponding between-run precisions were 5.3% for amphetamine and 6.7% for methamphetamine. The assay was linear for amphetamine and methamphetamine concentrations of 250 to 5,000 ng/mL (amphetamine, 1.9-37.0 micromol/L; methamphetamine, 1.7-33.6 micromol/L). The detection limit was 100 ng/mL (amphetamine, 0.74 micromol/L; methamphetamine, 0.67 micromol/L) using the scan mode

Atmospheric pressure chemical ionization of fluorinated phenols in atmospheric pressure chemical ionization mass spectrometry, tandem mass spectrometry, and ion mobility spectrometry

Science.gov (United States)

Eiceman, G. A.; Bergloff, J. F.; Rodriguez, J. E.; Munro, W.; Karpas, Z.

1999-01-01

Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) for fluorinated phenols (C6H5-xFxOH Where x = 0-5) in nitrogen with Cl- as the reagent ion yielded product ions of M Cl- through ion associations or (M-H)- through proton abstractions. Proton abstraction was controllable by potentials on the orifice and first lens, suggesting that some proton abstraction occurs through collision induced dissociation (CID) in the interface region. This was proven using CID of adduct ions (M Cl-) with Q2 studies where adduct ions were dissociated to Cl- or proton abstracted to (M-H)-. The extent of proton abstraction depended upon ion energy and structure in order of calculated acidities: pentafluorophenol > tetrafluorophenol > trifluorophenol > difluorophenol. Little or no proton abstraction occurred for fluorophenol, phenol, or benzyl alcohol analogs. Ion mobility spectrometry was used to determine if proton abstraction reactions passed through an adduct intermediate with thermalized ions and mobility spectra for all chemicals were obtained from 25 to 200 degrees C. Proton abstraction from M Cl- was not observed at any temperature for phenol, monofluorophenol, or difluorophenol. Mobility spectra for trifluorophenol revealed the kinetic transformations to (M-H)- either from M Cl- or from M2 Cl- directly. Proton abstraction was the predominant reaction for tetra- and penta-fluorophenols. Consequently, the evidence suggests that proton abstraction occurs from an adduct ion where the reaction barrier is reduced with increasing acidity of the O-H bond in C6H5-xFxOH.

NCI intramural research highlighted at 2014 AACR meeting

Science.gov (United States)

This year’s American Association for Cancer Research meeting featured plenary talks by two NCI scientists, Steven Rosenberg, M.D., and Louis Staudt, M.D., Ph.D., that highlighted the challenges in developing varied and potentially synergistic treatments f

NCI Core Open House Shines Spotlight on Supportive Science and Basic Research | Poster

Science.gov (United States)

The lobby of Building 549 at NCI at Frederick bustled with activity for two hours on Tuesday, May 1, as several dozen scientists and staff gathered for the NCI Core Open House. The event aimed to encourage discussion and educate visitors about the capabilities of the cores, laboratories, and facilities that offer support to NCI’s Center for Cancer Research.

Global Proteome Analysis of the NCI-60 Cell Line Panel

Directory of Open Access Journals (Sweden)

Amin Moghaddas Gholami

2013-08-01

Full Text Available The NCI-60 cell line collection is a very widely used panel for the study of cellular mechanisms of cancer in general and in vitro drug action in particular. It is a model system for the tissue types and genetic diversity of human cancers and has been extensively molecularly characterized. Here, we present a quantitative proteome and kinome profile of the NCI-60 panel covering, in total, 10,350 proteins (including 375 protein kinases and including a core cancer proteome of 5,578 proteins that were consistently quantified across all tissue types. Bioinformatic analysis revealed strong cell line clusters according to tissue type and disclosed hundreds of differentially regulated proteins representing potential biomarkers for numerous tumor properties. Integration with public transcriptome data showed considerable similarity between mRNA and protein expression. Modeling of proteome and drug-response profiles for 108 FDA-approved drugs identified known and potential protein markers for drug sensitivity and resistance. To enable community access to this unique resource, we incorporated it into a public database for comparative and integrative analysis (http://wzw.tum.de/proteomics/nci60.

Regioisomers of octanoic acid-containing structured triacylglycerols analyzed by tandem mass spectrometry using ammonia negative ion chemical ionization

DEFF Research Database (Denmark)

Kurvinen, J.P.; Mu, Huiling; Kallio, H.

2001-01-01

Tandem mass spectrometry based on ammonia negative ion chemical ionization and sample introduction via direct exposure probe was applied to analysis of regioisomeric structures of octanoic acid containing structured triacylglycerols (TAG) of type MML, MLM, MLL, and LML (M, medium-chain fatty acid...

Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

KAUST Repository

Hourani, Nadim

2013-10-01

Rationale Polycyclic aromatic sulfur heterocycles (PASHs) are detrimental species for refining processes in petroleum industry. Current mass spectrometric Methods that determine their composition are often preceded by derivatization and dopant addition approaches. Different ionization Methods have different impact on the molecular assignment of complex PASHs. The analysis of such species under atmospheric pressure chemical ionization (APCI) is still considered limited due to uncontrolled ion generation with low- and high-mass PASHs. Methods The ionization behavior of a model mixture of five selected PASH standards was investigated using an APCI source with nitrogen as the reagent gas. A complex thiophenic fraction was separated from a vacuum gas oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same ionization pattern was observed for the real thiophenic sample. It was found that S1 class species were the major sulfur-containing species found in the VGO sample. These species indicated the presence of alkylated benzothiophenic (BT), dibenzothiophenic (DBT) and benzonaphthothiophenic (BNT) series that were detected by APCI-FTICR MS. CONCLUSIONS This study provides an established APCI-FTICR MS method for the analysis of complex PASHs. PASHs were detected without using any derivatization and without fragmentation. The method can be used for the analysis of S-containing crude oil samples. © 2013 John Wiley & Sons, Ltd.

CHEMICAL ANALYSIS OF A DIFFUSE CLOUD ALONG A LINE OF SIGHT TOWARD W51: MOLECULAR FRACTION AND COSMIC-RAY IONIZATION RATE

Energy Technology Data Exchange (ETDEWEB)

Indriolo, Nick; Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Gerin, M. [LERMA, CNRS, Observatoire de Paris and ENS, F-75231 Paris Cedex 05 (France); Geballe, T. R. [Gemini Observatory, Hilo, HI 96720 (United States); Black, J. H. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Menten, K. M. [MPI fuer Radioastronomie, D-53121 Bonn (Germany); Goicoechea, J. R. [Departamento de Astrofisica, Centro de Astrobiologia (CSIC-INTA), E-28850 Madrid (Spain)

2012-10-20

Absorption lines from the molecules OH{sup +}, H{sub 2}O{sup +}, and H{sup +} {sub 3} have been observed in a diffuse molecular cloud along a line of sight near W51 IRS2. We present the first chemical analysis that combines the information provided by all three of these species. Together, OH{sup +} and H{sub 2}O{sup +} are used to determine the molecular hydrogen fraction in the outskirts of the observed cloud, as well as the cosmic-ray ionization rate of atomic hydrogen. H{sup +} {sub 3} is used to infer the cosmic-ray ionization rate of H{sub 2} in the molecular interior of the cloud, which we find to be {zeta}{sub 2} = (4.8 {+-} 3.4) Multiplication-Sign 10{sup -16} s{sup -1}. Combining the results from all three species we find an efficiency factor-defined as the ratio of the formation rate of OH{sup +} to the cosmic-ray ionization rate of H-of {epsilon} = 0.07 {+-} 0.04, much lower than predicted by chemical models. This is an important step in the future use of OH{sup +} and H{sub 2}O{sup +} on their own as tracers of the cosmic-ray ionization rate.

Chemical effects of ionizing radiation on the individual amino acids within intact and pure protein molecules. Final report

International Nuclear Information System (INIS)

Freidberg, F.

1977-01-01

Progress is reported on the following research projects: gamma radiation induced chemical and molecular weight changes in proteins; the free radical pattern for the irradiated protein; similarities in the mechanism of action of ionizing and of uv radiation; and spin trapping in the study of gamma radiolysis

NCI investment in nanotechnology: achievements and challenges for the future.

Science.gov (United States)

Dickherber, Anthony; Morris, Stephanie A; Grodzinski, Piotr

2015-01-01

Nanotechnology offers an exceptional and unique opportunity for developing a new generation of tools addressing persistent challenges to progress in cancer research and clinical care. The National Cancer Institute (NCI) recognizes this potential, which is why it invests roughly $150 M per year in nanobiotechnology training, research and development. By exploiting the various capacities of nanomaterials, the range of nanoscale vectors and probes potentially available suggests much is possible for precisely investigating, manipulating, and targeting the mechanisms of cancer across the full spectrum of research and clinical care. NCI has played a key role among federal R&D agencies in recognizing early the value of nanobiotechnology in medicine and committing to its development as well as providing training support for new investigators in the field. These investments have allowed many in the research community to pursue breakthrough capabilities that have already yielded broad benefits. Presented here is an overview of how NCI has made these investments with some consideration of how it will continue to work with this research community to pursue paradigm-changing innovations that offer relief from the burdens of cancer. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Technical sheets of ionizing radiations. 2. Non-ionizing radiations

International Nuclear Information System (INIS)

Anon.

1975-01-01

The biological effects of different non-ionizing radiations are studied: ultra-violet radiation, visible radiation, infrared radiation, micrometric waves, ultrasonics. In spite of their apparent diversity these radiations are similar in their physico-chemical effects, but in view of their widely varying production methods and types of application each type is considered separately. It is pointed out that no organization resembling the CIPR exists in the field of non-ionizing radiations, the result being a great disparity amongst the different legislations in force [fr

Ionizing radiation and a wood-based biorefinery

International Nuclear Information System (INIS)

Driscoll, Mark S.; Stipanovic, Arthur J.; Cheng, Kun; Barber, Vincent A.; Manning, Mellony; Smith, Jennifer L.; Sundar, Smith

2014-01-01

Woody biomass is widely available around the world. Cellulose is the major structural component of woody biomass and is the most abundant polymer synthesized by nature, with hemicellulose and lignin being second and third. Despite this great abundance, woody biomass has seen limited application outside of the paper and lumber industries. Its use as a feedstock for fuels and chemicals has been limited because of its highly crystalline structure, inaccessible morphology, and limited solubility (recalcitrance). Any economic use of woody biomass for the production of fuels and chemicals requires a “pretreatment” process to enhance the accessibility of the biomass to enzymes and/or chemical reagents. Electron beams (EB), X-rays, and gamma rays produce ions in a material which can then initiate chemical reactions and cleavage of chemical bonds. Such ionizing radiation predominantly scissions and degrades or depolymerizes both cellulose and hemicelluloses, less is known about its effects on lignin. This paper discusses how ionizing radiation can be used to make a wood-based biorefinery more environmentally friendly and profitable for its operators. - Highlights: • Ionizing radiation reduces the crystallinity of cellulose. • Ionizing radiation reduces cellulose's degree of polymerization. • The amount and rate of enzymatic hydrolysis of lignocellulosic materials, including wood, are increased with increasing radiation dose. • Wood and other lignocellulosic materials have the potential to be a renewable material for the production of chemicals and fuels

Ionization chambers

International Nuclear Information System (INIS)

Boag, J.W.

1987-01-01

Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

Fast screening of analytes for chemical reactions by reactive low-temperature plasma ionization mass spectrometry.

Science.gov (United States)

Zhang, Wei; Huang, Guangming

2015-11-15

Approaches for analyte screening have been used to aid in the fine-tuning of chemical reactions. Herein, we present a simple and straightforward analyte screening method for chemical reactions via reactive low-temperature plasma ionization mass spectrometry (reactive LTP-MS). Solution-phase reagents deposited on sample substrates were desorbed into the vapor phase by action of the LTP and by thermal desorption. Treated with LTP, both reagents reacted through a vapor phase ion/molecule reaction to generate the product. Finally, protonated reagents and products were identified by LTP-MS. Reaction products from imine formation reaction, Eschweiler-Clarke methylation and the Eberlin reaction were detected via reactive LTP-MS. Products from the imine formation reaction with reagents substituted with different functional groups (26 out of 28 trials) were successfully screened in a time of 30 s each. Besides, two short-lived reactive intermediates of Eschweiler-Clarke methylation were also detected. LTP in this study serves both as an ambient ionization source for analyte identification (including reagents, intermediates and products) and as a means to produce reagent ions to assist gas-phase ion/molecule reactions. The present reactive LTP-MS method enables fast screening for several analytes from several chemical reactions, which possesses good reagent compatibility and the potential to perform high-throughput analyte screening. In addition, with the detection of various reactive intermediates (intermediates I and II of Eschweiler-Clarke methylation), the present method would also contribute to revealing and elucidating reaction mechanisms. Copyright © 2015 John Wiley & Sons, Ltd.

Pharmacologically directed strategies in academic anticancer drug discovery based on the European NCI compounds initiative.

Science.gov (United States)

Hendriks, Hans R; Govaerts, Anne-Sophie; Fichtner, Iduna; Burtles, Sally; Westwell, Andrew D; Peters, Godefridus J

2017-07-11

The European NCI compounds programme, a joint initiative of the EORTC Research Branch, Cancer Research Campaign and the US National Cancer Institute, was initiated in 1993. The objective was to help the NCI in reducing the backlog of in vivo testing of potential anticancer compounds, synthesised in Europe that emerged from the NCI in vitro 60-cell screen. Over a period of more than twenty years the EORTC-Cancer Research Campaign panel reviewed ∼2000 compounds of which 95 were selected for further evaluation. Selected compounds were stepwise developed with clear go/no go decision points using a pharmacologically directed programme. This approach eliminated quickly compounds with unsuitable pharmacological properties. A few compounds went into Phase I clinical evaluation. The lessons learned and many of the principles outlined in the paper can easily be applied to current and future drug discovery and development programmes. Changes in the review panel, restrictions regarding numbers and types of compounds tested in the NCI in vitro screen and the appearance of targeted agents led to the discontinuation of the European NCI programme in 2017 and its transformation into an academic platform of excellence for anticancer drug discovery and development within the EORTC-PAMM group. This group remains open for advice and collaboration with interested parties in the field of cancer pharmacology.

Amorphous silicon ionizing particle detectors

Science.gov (United States)

Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

1988-01-01

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

Chemical and biological effects of β-decay and inner shell ionization in biomolecules

International Nuclear Information System (INIS)

Stoecklin, G.

1979-01-01

Tritium and iodine-125, and the Auger effect either caused by the EC-decay of 125 I or by the inner shell vacancy created selectively by mono-energetic X-ray are reviewed in this paper. The specifically labelled precursors to bound 3 H large biomolecules were prepared by conventional syntheses, and then incorporated into the DNA of proliferating cells. The effects like DNA strand breaks or mutational changes are likely to be affected by the localization of the carbonium ions in biological molecules. In contrast to lethality, it was demonstrated that 3 H transmutation effect contributed to DNA strand breaks and played a key role in producing genetic effects. The decay of 3 H in uracil-5- 3 H in the DNA of E. coli was about 7 times as mutagenic as that in uracil-6- 3 H, and 500-fold greater in bacteriophage S13. Drastic chemical consequences are associated with the Auger effect occurring as a possible relaxation process whenever inner shell ionization is initiated. When the vacancy is filled by an electron from an outer shell, the bond energy difference between inner shell electron and outer shell electron is released either in the form of an X-ray fluorescence photon or it can be transmitted to another outer electron which is then ejected. The radioactive decay in specifically labelled biomolecules or the inner shell ionization in heavy constituent atoms caused by resonant X-ray are relevant to a) selective microsurgery in biological macromolecules for the correlation of biological and chemical functions, b) radiotoxicity estimation, and c) radiation therapy. (Yamashita, S.)

Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

Energy Technology Data Exchange (ETDEWEB)

Smith, Philip A., E-mail: Smith.Philip.A@dol.gov [Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biometrics, 4301 Jones Bridge Road, Bethesda, MD, 20814 (United States); Lepage, Carmela R. Jackson [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada); Savage, Paul B. [Brigham Young University, Department of Chemistry and Biochemistry, Provo, UT, 84602 (United States); Bowerbank, Christopher R.; Lee, Edgar D. [Torion Technologies Inc., 796 East Utah Valley Drive, Suite 200, American Fork, UT, 84003 (United States); Lukacs, Michael J. [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada)

2011-04-01

The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H]{sup +}) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H]{sup +} ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d{sub 15} provided evidence that [M+H]{sup +} production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H]{sup +} ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.

Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

International Nuclear Information System (INIS)

Smith, Philip A.; Lepage, Carmela R. Jackson; Savage, Paul B.; Bowerbank, Christopher R.; Lee, Edgar D.; Lukacs, Michael J.

2011-01-01

The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H] + ) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H] + ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d 15 provided evidence that [M+H] + production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H] + ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.

The ionizing treatment of food

International Nuclear Information System (INIS)

1998-01-01

This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

Effects of ionizing radiation in the physico-chemical characteristics of red wine Cabernet Sauvignon

International Nuclear Information System (INIS)

Silva, Fellipe Souza da; Leiras, Anderson; Wagner, Walsan

2014-01-01

The oenology in the current days is increasingly aimed obtain improvements on wine quality produced without there the deterioration of characteristics of the same, using new technologies for such order. The objective of present work will be the application of the radiation ionizing in wines Cabernet Sauvignon, with the interest of analyzing its effects on physic-chemical characteristics of this wines, such as quality, aging and etc. Were analyzed the following strands: degree alcoholic; dry extract; density and absorbance with spectrometer (420, 520 and 620 nm). (author)

Role of ionizing radiation in chemical evolution studies

International Nuclear Information System (INIS)

Albarran, G.; Negron-Mendoza, A.; Trevino, C.; Torres, J.L.

1988-01-01

The purpose of this paper is to emphasize the role of ionizing radiation in radiation-induced reactions in prebiotic chemistry. The use of ionizing radiation as an energy source is based on its unique qualities, its specific manner of energy deposition and its abundance in the Earth's crust. As an example of radiation-induced reactions, the radiolysis of malonic acid was investigated. Malonic acid is converted into other carboxylic acids. The results obtained have been correlated with the ready formation of this compound in prebiotic experiments. (author)

Characterization of nitrated sugar alcohols by atmospheric-pressure chemical-ionization mass spectrometry.

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Ostrinskaya, Alla; Kelley, Jude A; Kunz, Roderick R

2017-02-28

The nitrated sugar alcohols mannitol hexanitrate (MHN), sorbitol hexanitrate (SHN) and xylitol pentanitrate (XPN) are in the same class of compounds as the powerful military-grade explosive pentaerythritol tetranitrate (PETN) and the homemade explosive erythritol tetranitrate (ETN) but, unlike for PETN and ETN, ways to detect MHN, SHN and XPN by mass spectrometry (MS) have not been fully investigated. Atmospheric-pressure chemical-ionization mass spectrometry (APCI-MS) was used to detect ions characteristic of nitrated sugar alcohols. APCI time-of-flight mass spectrometry (APCI-TOF MS) and collision-induced dissociation tandem mass spectrometry (CID MS/MS) were used for confirmation of each ion assignment. In addition, the use of the chemical ionization reagent dichloromethane was investigated to improve sensitivity and selectivity for detection of MHN, SHN and XPN. All the nitrated sugar alcohols studied followed similar fragmentation pathways in the APCI source. MHN, SHN and XPN were detectable as fragment ions formed by the loss of NO 2 , HNO 2 , NO 3 , and CH 2 NO 2 groups, and in the presence of dichloromethane chlorinated adduct ions were observed. It was determined that in MS/MS mode, chlorinated adducts of MHN and SHN had the lowest limits of detection (LODs), while for XPN the lowest LOD was for the [XPN-NO 2 ] - fragment ion. Partially nitrated analogs of each of the three compounds were also present in the starting materials, and ions attributable to these compounds versus those formed from in-source fragmentation of MHN, SHN, and XPN were distinguished and assigned using liquid chromatography APCI-MS and ESI-MS. The APCI-MS technique provides a selective and sensitive method for the detection of nitrated sugar alcohols. The methods disclosed here will benefit the area of explosives trace detection for counterterrorism and forensics. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

UNC Cancer Center Director to Lead NCI.

Science.gov (United States)

2017-08-01

President Donald Trump has selected Norman "Ned" Sharpless, MD, director of the University of North Carolina Lineberger Comprehensive Cancer Center, to lead the NCI. The news was met with widespread approval among cancer researchers, who view Sharpless as a strong communicator who can ably represent the needs of the cancer community in the face of proposed funding cuts. ©2017 American Association for Cancer Research.

Creating Start-up Companies around NCI Inventions | Poster

Science.gov (United States)

By Karen Surabian, Thomas Stackhouse, and Rose Freel, Contributing Writers, and Rosemarie Truman, Guest Writer The National Cancer Institute (NCI), led by the Technology Transfer Center (TTC),  the Avon Foundation, and The Center for Advancing Innovation have partnered to create a “first-of-a-kind” Breast Cancer Start-up Challenge.

Help NCI at Frederick “Knock Out Hunger” | Poster

Science.gov (United States)

NCI at Frederick is once again participating in the Feds Feed Families initiative, an annual food drive that addresses severe shortages of non-perishable items in food banks across D.C., Maryland, and Virginia during the summer months, when giving is at its lowest.

Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

International Nuclear Information System (INIS)

Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae; An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop

2010-01-01

In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field

Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae [Sejong University, Seoul (Korea, Republic of); An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop [Wooju Communication and Technology Co., Seoul (Korea, Republic of)

2010-08-15

In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field.

Virtual quantification of metabolites by capillary electrophoresis-electrospray ionization-mass spectrometry: predicting ionization efficiency without chemical standards.

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Chalcraft, Kenneth R; Lee, Richard; Mills, Casandra; Britz-McKibbin, Philip

2009-04-01

A major obstacle in metabolomics remains the identification and quantification of a large fraction of unknown metabolites in complex biological samples when purified standards are unavailable. Herein we introduce a multivariate strategy for de novo quantification of cationic/zwitterionic metabolites using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) based on fundamental molecular, thermodynamic, and electrokinetic properties of an ion. Multivariate calibration was used to derive a quantitative relationship between the measured relative response factor (RRF) of polar metabolites with respect to four physicochemical properties associated with ion evaporation in ESI-MS, namely, molecular volume (MV), octanol-water distribution coefficient (log D), absolute mobility (mu(o)), and effective charge (z(eff)). Our studies revealed that a limited set of intrinsic solute properties can be used to predict the RRF of various classes of metabolites (e.g., amino acids, amines, peptides, acylcarnitines, nucleosides, etc.) with reasonable accuracy and robustness provided that an appropriate training set is validated and ion responses are normalized to an internal standard(s). The applicability of the multivariate model to quantify micromolar levels of metabolites spiked in red blood cell (RBC) lysates was also examined by CE-ESI-MS without significant matrix effects caused by involatile salts and/or major co-ion interferences. This work demonstrates the feasibility for virtual quantification of low-abundance metabolites and their isomers in real-world samples using physicochemical properties estimated by computer modeling, while providing deeper insight into the wide disparity of solute responses in ESI-MS. New strategies for predicting ionization efficiency in silico allow for rapid and semiquantitative analysis of newly discovered biomarkers and/or drug metabolites in metabolomics research when chemical standards do not exist.

Phenethyl Isothiocyanate Induces Apoptotic Cell Death Through the Mitochondria-dependent Pathway in Gefitinib-resistant NCI-H460 Human Lung Cancer Cells In Vitro.

Science.gov (United States)

Hsia, Te-Chun; Huang, Yi-Ping; Jiang, Yi-Wen; Chen, Hsin-Yu; Cheng, Zheng-Yu; Hsiao, Yung-Ting; Chen, Cheng-Yen; Peng, Shu-Fen; Chueh, Fu-Shin; Chou, Yu-Cheng; Chung, Jing-Gung

2018-04-01

Some lung cancer patients treated with gefitinib develop resistance to this drug resulting in unsatisfactory treatment outcomes. Phenethyl isothiocyanate (PEITC), present in our common cruciferous vegetables, exhibits anticancer activities in many human cancer cell lines. Currently, there is no available information on the possible modification of gefitinib resistance of lung cancer in vitro by PEITC. Thus, the effects of PEITC on gefitinib resistant lung cancer NCI-H460 cells were investigated in vitro. The total cell viability, apoptotic cell death, production of reactive oxygen species (ROS) and Ca 2+ , levels of mitochondria membrane potential (ΔΨ m ) and caspase-3, -8 and -9 activities were measured by flow cytometry assay. PEITC induced chromatin condensation was examined by DAPI staining. PEITC-induced cell morphological changes, decreased total viable cell number and induced apoptotic cell death in NCI-H460 and NCI-H460/G cells. PEITC decreased ROS production in NCI-H460 cells, but increased production in NCI-H460/G cells. PEITC increased Ca 2+ production, decreased the levels of ΔΨ m and increased caspase-3, -8 and -9 activities in both NCI-H460 and NCI-H460/G cells. Western blotting was used to examine the effect of apoptotic cell death associated protein expression in NCI-H460 NCI-H460/G cells after exposure to PEITC. Results showed that PEITC increased expression of cleaved caspase-3, PARP, GADD153, Endo G and pro-apoptotic protein Bax in NCI-H460/G cells. Based on these results, we suggest that PEITC induces apoptotic cell death via the caspase- and mitochondria-dependent pathway in NCI-H460/G cells. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

77 FR 2734 - Proposed Collection; Comment Request: Solar Cell: A Mobile UV Manager for Smart Phones (NCI)

Science.gov (United States)

2012-01-19

... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Proposed Collection; Comment Request: Solar Cell: A Mobile UV Manager for Smart Phones (NCI) SUMMARY: In compliance with the... Manager for Smart Phones (NCI). Type of Information Collection Request: New. Need and Use of Information...

The generalizability of NCI-sponsored clinical trials accrual among women with gynecologic malignancies.

Science.gov (United States)

Mishkin, Grace; Minasian, Lori M; Kohn, Elise C; Noone, Anne-Michelle; Temkin, Sarah M

2016-12-01

Enrollment of a representative population to cancer clinical trials ensures scientific reliability and generalizability of results. This study evaluated the similarity of patients enrolled in NCI-supported group gynecologic cancer trials to the incident US population. Accrual to NCI-sponsored ovarian, uterine, and cervical cancer treatment trials between 2003 and 2012 were examined. Race, ethnicity, age, and insurance status were compared to the analogous US patient population estimated using adjusted SEER incidence data. There were 18,913 accruals to 156 NCI-sponsored gynecologic cancer treatment trials, ovarian (56%), uterine (32%), and cervical cancers (12%). Ovarian cancer trials included the least racial, ethnic and age diversity. Black women were notably underrepresented in ovarian trials (4% versus 11%). Hispanic patients were underrepresented in ovarian and uterine trials (4% and 5% versus 18% and 19%, respectively), but not in cervical cancer trials (14 versus 11%). Elderly patients were underrepresented in each disease area, with the greatest underrepresentation seen in ovarian cancer patients over the age of 75 (7% versus 29%). Privately insured women were overrepresented among accrued ovarian cancer patients (87% versus 76%), and the uninsured were overrepresented among women with uterine or cervical cancers. These patterns did not change over time. Several notable differences were observed between the patients accrued to NCI funded trials and the incident population. Improving representation of racial and ethnic minorities and elderly patients on cancer clinical trials continues to be a challenge and priority. Copyright © 2016 Elsevier Inc. All rights reserved.

Regular paths in SparQL: querying the NCI Thesaurus.

Science.gov (United States)

Detwiler, Landon T; Suciu, Dan; Brinkley, James F

2008-11-06

OWL, the Web Ontology Language, provides syntax and semantics for representing knowledge for the semantic web. Many of the constructs of OWL have a basis in the field of description logics. While the formal underpinnings of description logics have lead to a highly computable language, it has come at a cognitive cost. OWL ontologies are often unintuitive to readers lacking a strong logic background. In this work we describe GLEEN, a regular path expression library, which extends the RDF query language SparQL to support complex path expressions over OWL and other RDF-based ontologies. We illustrate the utility of GLEEN by showing how it can be used in a query-based approach to defining simpler, more intuitive views of OWL ontologies. In particular we show how relatively simple GLEEN-enhanced SparQL queries can create views of the OWL version of the NCI Thesaurus that match the views generated by the web-based NCI browser.

Gardasil® and Cervarix® | NCI Technology Transfer Center | TTC

Science.gov (United States)

Vaccine for human papilloma virus (HPV) to protect from cancers Key elements of the technology for Gardasil® and Cervarix originated from the HPV research of the laboratory of Drs. Douglas Lowy and John Schiller of the NCI.

Curcumin Inhibits Growth of Human NCI-H292 Lung Squamous Cell Carcinoma Cells by Increasing FOXA2 Expression

Directory of Open Access Journals (Sweden)

Lingling Tang

2018-02-01

Full Text Available Lung squamous cell carcinoma (LSCC is a common histological lung cancer subtype, but unlike lung adenocarcinoma, limited therapeutic options are available for treatment. Curcumin, a natural compound, may have anticancer effects in various cancer cells, but how it may be used to treat LSCC has not been well studied. Here, we applied curcumin to a human NCI-H292 LSCC cell line to test anticancer effects and explored underlying potential mechanisms of action. Curcumin treatment inhibited NCI-H292 cell growth and increased FOXA2 expression in a time-dependent manner. FOXA2 expression was decreased in LSCC tissues compared with adjacent normal tissues and knockdown of FOXA2 increased NCI-H292 cells proliferation. Inhibition of cell proliferation by curcumin was attenuated by FOXA2 knockdown. Moreover inhibition of STAT3 pathways by curcumin increased FOXA2 expression in NCI-H292 cells whereas a STAT3 activator (IL-6 significantly inhibited curcumin-induced FOXA2 expression. Also, SOCS1 and SOCS3, negative regulators of STAT3 activity, were upregulated by curcumin treatment. Thus, curcumin inhibited human NCI-H292 cells growth by increasing FOXA2 expression via regulation of STAT3 signaling pathways.

Quantitative correlations between collision induced dissociation mass spectrometry coupled with electrospray ionization or atmospheric pressure chemical ionization mass spectrometry - Experiment and theory

Science.gov (United States)

Ivanova, Bojidarka; Spiteller, Michael

2018-04-01

The problematic that we consider in this paper treats the quantitative correlation model equations between experimental kinetic and thermodynamic parameters of coupled electrospray ionization (ESI) mass spectrometry (MS) or atmospheric pressure chemical ionization (APCI) mass spectrometry with collision induced dissociation mass spectrometry, accounting for the fact that the physical phenomena and mechanisms of ESI- and APCI-ion formation are completely different. There are described forty two fragment reactions of three analytes under independent ESI- and APCI-measurements. The developed new quantitative models allow us to study correlatively the reaction kinetics and thermodynamics using the methods of mass spectrometry, which complementary application with the methods of the quantum chemistry provide 3D structural information of the analytes. Both static and dynamic quantum chemical computations are carried out. The object of analyses are [2,3-dimethyl-4-(4-methyl-benzoyl)-2,3-di-p-tolyl-cyclobutyl]-p-tolyl-methanone (1) and the polycyclic aromatic hydrocarbons derivatives of dibenzoperylen (2) and tetrabenzo [a,c,fg,op]naphthacene (3), respectively. As far as (1) is known to be a product of [2π+2π] cycloaddition reactions of chalcone (1,3-di-p-tolyl-propenone), however producing cyclic derivatives with different stereo selectivity, so that the study provide crucial data about the capability of mass spectrometry to provide determine the stereo selectivity of the analytes. This work also first provides quantitative treatment of the relations '3D molecular/electronic structures'-'quantum chemical diffusion coefficient'-'mass spectrometric diffusion coefficient', thus extending the capability of the mass spectrometry for determination of the exact 3D structure of the analytes using independent measurements and computations of the diffusion coefficients. The determination of the experimental diffusion parameters is carried out within the 'current monitoring method

The NCI Alliance for Nanotechnology in Cancer: achievement and path forward.

Science.gov (United States)

Ptak, Krzysztof; Farrell, Dorothy; Panaro, Nicholas J; Grodzinski, Piotr; Barker, Anna D

2010-01-01

Nanotechnology is a 'disruptive technology', which can lead to a generation of new diagnostic and therapeutic products, resulting in dramatically improved cancer outcomes. The National Cancer Institute (NCI) of National Institutes of Health explores innovative approaches to multidisciplinary research allowing for a convergence of molecular biology, oncology, physics, chemistry, and engineering and leading to the development of clinically worthy technological approaches. These initiatives include programmatic efforts to enable nanotechnology as a driver of advances in clinical oncology and cancer research, known collectively as the NCI Alliance for Nanotechnology in Cancer (ANC). Over the last 5 years, ANC has demonstrated that multidisciplinary approach catalyzes scientific developments and advances clinical translation in cancer nanotechnology. The research conducted by ANC members has improved diagnostic assays and imaging agents, leading to the development of point-of-care diagnostics, identification and validation of numerous biomarkers for novel diagnostic assays, and the development of multifunctional agents for imaging and therapy. Numerous nanotechnology-based technologies developed by ANC researchers are entering clinical trials. NCI has re-issued ANC program for next 5 years signaling that it continues to have high expectations for cancer nanotechnology's impact on clinical practice. The goals of the next phase will be to broaden access to cancer nanotechnology research through greater clinical translation and outreach to the patient and clinical communities and to support development of entirely new models of cancer care.

ANALYSIS AND IDENTIFICATION SPIKING CHEMICAL COMPOUNDS RELATED TO CHEMICAL WEAPON CONVENTION IN UNKNOWN WATER SAMPLES USING GAS CHROMATOGRAPHY AND GAS CHROMATOGRAPHY ELECTRON IONIZATION MASS SPECTROMETRY

Directory of Open Access Journals (Sweden)

Harry Budiman

2010-06-01

Full Text Available The identification and analysis of chemical warfare agents and their degradation products is one of important component for the implementation of the convention. Nowadays, the analytical method for determination chemical warfare agent and their degradation products has been developing and improving. In order to get the sufficient analytical data as recommended by OPCW especially in Proficiency Testing, the spiking chemical compounds related to Chemical Weapon Convention in unknown water sample were determined using two different techniques such as gas chromatography and gas chromatography electron-impact ionization mass spectrometry. Neutral organic extraction, pH 11 organic extraction, cation exchanged-methylation, triethylamine/methanol-silylation were performed to extract the chemical warfare agents from the sample, before analyzing with gas chromatography. The identification of chemical warfare agents was carried out by comparing the mass spectrum of chemicals with mass spectrum reference from the OPCW Central Analytical Database (OCAD library while the retention indices calculation obtained from gas chromatography analysis was used to get the confirmation and supported data of  the chemical warfare agents. Diisopropyl methylphosphonate, 2,2-diphenyl-2-hydroacetic acid and 3-quinuclidinol were found in unknown water sample. Those chemicals were classified in schedule 2 as precursor or reactant of chemical weapons compound in schedule list of Chemical Weapon Convention.   Keywords: gas chromatography, mass spectrometry, retention indices, OCAD library, chemical warfare agents

Measurement of the first ionization potential of astatine by laser ionization spectroscopy

Science.gov (United States)

Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

2013-01-01

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

How You Can Partner with NIH | NCI Technology Transfer Center | TTC

Science.gov (United States)

NCI Technology Transfer Center (TTC) provides an array of agreements to support the National Cancer Institute's partnering. Deciding which type of agreement to use can be a challenge: CRADA, MTA, collaboration, agreement, CTA, Materials-CRADA

History of the Diet History Questionnaire (DHQ) | EGRP/DCCPS/NCI/NIH

Science.gov (United States)

Learn about the evolution of the Diet History Questionnaire (DHQ), developed by the National Cancer Institute (NCI) initially in 2001, to the DHQ II in 2010, up to the present version, DHQ III, launched in 2018.

Evaluation of the UF/NCI hybrid computational phantoms for use in organ dosimetry of pediatric patients undergoing fluoroscopically guided cardiac procedures

Science.gov (United States)

Marshall, Emily L.; Borrego, David; Tran, Trung; Fudge, James C.; Bolch, Wesley E.

2018-03-01

Epidemiologic data demonstrate that pediatric patients face a higher relative risk of radiation induced cancers than their adult counterparts at equivalent exposures. Infants and children with congenital heart defects are a critical patient population exposed to ionizing radiation during life-saving procedures. These patients will likely incur numerous procedures throughout their lifespan, each time increasing their cumulative radiation absorbed dose. As continued improvements in long-term prognosis of congenital heart defect patients is achieved, a better understanding of organ radiation dose following treatment becomes increasingly vital. Dosimetry of these patients can be accomplished using Monte Carlo radiation transport simulations, coupled with modern anatomical patient models. The aim of this study was to evaluate the performance of the University of Florida/National Cancer Institute (UF/NCI) pediatric hybrid computational phantom library for organ dose assessment of patients that have undergone fluoroscopically guided cardiac catheterizations. In this study, two types of simulations were modeled. A dose assessment was performed on 29 patient-specific voxel phantoms (taken as representing the patient’s true anatomy), height/weight-matched hybrid library phantoms, and age-matched reference phantoms. Two exposure studies were conducted for each phantom type. First, a parametric study was constructed by the attending pediatric interventional cardiologist at the University of Florida to model the range of parameters seen clinically. Second, four clinical cardiac procedures were simulated based upon internal logfiles captured by a Toshiba Infinix-i Cardiac Bi-Plane fluoroscopic unit. Performance of the phantom library was quantified by computing both the percent difference in individual organ doses, as well as the organ dose root mean square values for overall phantom assessment between the matched phantoms (UF/NCI library or reference) and the patient

Russian delegation visits NIH and NCI to discuss research collaboration

Science.gov (United States)

The NCI Center for Global Health hosted a delegation from the Russian Foundation for Basic Research to discuss ongoing and future collaborations in cancer research. The delegation was accompanied by representatives from the US Embassy in Moscow and the Embassy of the Russian Federation in Washington DC.

NIH Employee Invention Report (EIR) | NCI Technology Transfer Center | TTC

Science.gov (United States)

NIH researchers must immediately contact their Laboratory or Branch Chief and inform him or her of a possible invention, and then consult with your NCI TTC Technology Transfer Manager about submitting an Employee Invention Report (EIR) Form. | [google6f4cd5334ac394ab.html

Microsynthesis and electron ionization mass spectral studies of O(S)-alkyl N,N-dimethyl alkylphosphono(thiolo)thionoamidates for Chemical Weapons Convention verification.

Science.gov (United States)

Saeidian, Hamdollah; Babri, Mehran; Abdoli, Morteza; Sarabadani, Mansour; Ashrafi, Davood; Naseri, Mohammad Taghi

2012-12-15

The availability of mass spectra and interpretation skills are essential for unambiguous identification of the Chemical Weapons Convention (CWC)-related chemicals. The O(S)-alkyl N,N-dimethyl alkylphosphono(thiolo)thionoamidates are included in the list of scheduled CWC-related compounds, but there are very few spectra from these compounds in the literature. This paper examines these spectra and their mass spectral fragmentation routes. The title chemicals were prepared through microsynthetic protocols and were analyzed using electron ionization mass spectrometry with gas chromatography as a MS-inlet system. Structures of fragments were confirmed using analysis of fragment ions of deuterated analogs, tandem mass spectrometry and density functional theory (DFT) calculations. Mass spectrometric studies revealed some interesting fragmentation pathways during the ionization process, such as alkene and amine elimination and McLafferty-type rearrangements. The most important fragmentation route of the chemicals is the thiono-thiolo rearrangement. DFT calculations are used to support MS results and to reveal relative preference formation of fragment ions. The retention indices (RIs) of all the studied compounds are also reported. Mass spectra of the synthesized compounds were investigated with the aim to enrich the Organization for the Prohibition of Chemical Weapons (OPCW) Central Analytical Database (OCAD) which may be used for detection and identification of CWC-related chemicals during on-site inspection and/or off-site analysis such as OPCW proficiency tests. Copyright © 2012 John Wiley & Sons, Ltd.

Determination of sulfonamides in meat by liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Kim, Dal Ho; Choi, Jong Oh; Kim, Jin Seog; Lee, Dai Woon

2002-01-01

Liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) has been used for the determination of sulfonamides in meat. Five typical sulfonamides were selected as target compounds, and beef meat was selected as a matrix sample. As internal standards, sulfapyridine and isotope labeled sulfamethazine ( 13 C 6 -SMZ) were used. Compared to the results of recent reports, our results have shown improved precision to a RSD of 1.8% for the determination of sulfamethazine spiked with 75 ng/g level in meat

IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

International Nuclear Information System (INIS)

Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

2013-01-01

Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10 –7 ) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10 –6 -1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H 2 , or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks

Airborne observations of formic acid using a chemical ionization mass spectrometer

Directory of Open Access Journals (Sweden)

M. Le Breton

2012-12-01

Full Text Available The first airborne measurements of formic acid mixing ratios over the United Kingdom were measured on the FAAM BAe-146 research aircraft on 16 March 2010 with a chemical ionization mass spectrometer using I⁻ reagent ions. The I⁻ ionization scheme was able to measure formic acid mixing ratios at 1 Hz in the boundary layer.

In-flight standard addition calibrations from a formic acid source were used to determine the instrument sensitivity of 35 ± 6 ion counts pptv⁻¹ s⁻¹ and a limit of detection of 25 pptv. Routine measurements were made through a scrubbed inlet to determine the instrumental background. Three plumes of formic acid were observed over the UK, originating from London, Humberside and Tyneside. The London plume had the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv. No significant correlations of formic acid with NO_x and ozone were found, but a positive correlation was observed between CO and HCOOH within the two plumes where coincident data were recorded.

A trajectory model was employed to determine the sources of the plumes and compare modelled mixing ratios with measured values. The model underestimated formic acid concentrations by up to a factor of 2. This is explained by missing sources in the model, which were considered to be both primary emissions of formic acid of mainly anthropogenic origin and a lack of precursor emissions, such as isoprene, from biogenic sources, whose oxidation in situ would lead to formic acid formation.

The technique of negative ions in mass spectrometry. Application to aromatics

International Nuclear Information System (INIS)

George, G.

1984-01-01

The author examines the application of NCI (study of negative ions created by chemical ionization and particularly by a reacting negative ion) on a model popular at the present time: the passion fruit. The author stresses that this technique has its limitations and should be considered as auxiliary to electron impact. However, it seems destined for a promising future for the analysis of natural produce [fr

Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry.

Science.gov (United States)

Lin, Shu-Hsuan; Lo, Ta-Ju; Kuo, Fang-Yin; Chen, Yu-Chie

2014-01-01

Ultrasonication has been used to accelerate chemical reactions. It would be ideal if ultrasonication-assisted chemical reactions could be monitored by suitable detection tools such as mass spectrometry in real time. It would be helpful to clarify reaction intermediates/products and to have a better understanding of reaction mechanism. In this work, we developed a system for ultrasonication-assisted spray ionization mass spectrometry (UASI-MS) with an ~1.7 MHz ultrasonic transducer to monitor chemical reactions in real time. We demonstrated that simply depositing a sample solution on the MHz-based ultrasonic transducer, which was placed in front of the orifice of a mass spectrometer, the analyte signals can be readily detected by the mass spectrometer. Singly and multiply charged ions from small and large molecules, respectively, can be observed in the UASI mass spectra. Furthermore, the ultrasonic transducer used in the UASI setup accelerates the chemical reactions while being monitored via UASI-MS. The feasibility of using this approach for real-time acceleration/monitoring of chemical reactions was demonstrated. The reactions of Girard T reagent and hydroxylamine with steroids were used as the model reactions. Upon the deposition of reactant solutions on the ultrasonic transducer, the intermediate/product ions are readily generated and instantaneously monitored using MS within 1 s. Additionally, we also showed the possibility of using this reactive UASI-MS approach to assist the confirmation of trace steroids from complex urine samples by monitoring the generation of the product ions. Copyright © 2014 John Wiley & Sons, Ltd.

Ionizing Radiation Processing Technology

International Nuclear Information System (INIS)

Rida Tajau; Kamarudin Hashim; Jamaliah Sharif; Ratnam, C.T.; Keong, C.C.

2017-01-01

This book completely brief on the basic concept and theory of ionizing radiation in polymers material processing. Besides of that the basic concept of polymerization addition, cross-linking and radiation degradation also highlighted in this informative book. All of the information is from scientific writing based on comprehensive scientific research in polymerization industry which using the radiation ionizing. It is very useful to other researcher whose study in Nuclear Sciencea and Science of Chemical and Material to use this book as a guideline for them in future scientific esearch.

Involvement of MAPK proteins in bystander effects induced by chemicals and ionizing radiation

International Nuclear Information System (INIS)

Asur, Rajalakshmi; Balasubramaniam, Mamtha; Marples, Brian; Thomas, Robert A.; Tucker, James D.

2010-01-01

Many studies have examined bystander effects induced by ionizing radiation, however few have evaluated the ability of chemicals to induce similar effects. We previously reported the ability of two chemicals, mitomycin C (MMC) and phleomycin (PHL) to induce bystander effects in normal human lymphoblastoid cell lines. The focus of the current study was to determine the involvement of the MAPK proteins in bystander effects induced by physical and chemical DNA damaging agents and to evaluate the effects of MAPK inhibition on bystander-induced caspase 3/7 activation. The phosphorylation levels of the MAPK proteins ERK1/2, JNK, and p38, were measured from 1 to 24 h following direct or bystander exposure to MMC, PHL or radiation. We observed transient phosphorylation, at early time points, of all 3 proteins in bystander cells. We also evaluated the effect of MAPK inhibition on bystander-induced caspase 3/7 activity to determine the role of MAPK proteins in bystander-induced apoptosis. We observed bystander-induced activation of caspase 3/7 in bystander cells. Inhibition of MAPK proteins resulted in a decrease in caspase 3/7 activity at the early time points, and the caspase activity increased (in the case of ERK inhibition) or returned to basal levels (in the case of JNK or p38 inhibition) between 12 and 24 h. PHL is considered to be a radiomimetic agent, however in the present study PHL behaved more like a chemical and not like radiation in terms of MAPK phosphorylation. These results point to the involvement of MAPK proteins in the bystander effect induced by radiation and chemicals and provide additional evidence that this response is not limited to radiation but is a generalized stress response in cells.

CellMiner: a relational database and query tool for the NCI-60 cancer cell lines

Directory of Open Access Journals (Sweden)

Reinhold William C

2009-06-01

Full Text Available Abstract Background Advances in the high-throughput omic technologies have made it possible to profile cells in a large number of ways at the DNA, RNA, protein, chromosomal, functional, and pharmacological levels. A persistent problem is that some classes of molecular data are labeled with gene identifiers, others with transcript or protein identifiers, and still others with chromosomal locations. What has lagged behind is the ability to integrate the resulting data to uncover complex relationships and patterns. Those issues are reflected in full form by molecular profile data on the panel of 60 diverse human cancer cell lines (the NCI-60 used since 1990 by the U.S. National Cancer Institute to screen compounds for anticancer activity. To our knowledge, CellMiner is the first online database resource for integration of the diverse molecular types of NCI-60 and related meta data. Description CellMiner enables scientists to perform advanced querying of molecular information on NCI-60 (and additional types through a single web interface. CellMiner is a freely available tool that organizes and stores raw and normalized data that represent multiple types of molecular characterizations at the DNA, RNA, protein, and pharmacological levels. Annotations for each project, along with associated metadata on the samples and datasets, are stored in a MySQL database and linked to the molecular profile data. Data can be queried and downloaded along with comprehensive information on experimental and analytic methods for each data set. A Data Intersection tool allows selection of a list of genes (proteins in common between two or more data sets and outputs the data for those genes (proteins in the respective sets. In addition to its role as an integrative resource for the NCI-60, the CellMiner package also serves as a shell for incorporation of molecular profile data on other cell or tissue sample types. Conclusion CellMiner is a relational database tool for

Non-polar lipids characterization of Quinoa (Chenopodium quinoa) seed by comprehensive two-dimensional gas chromatography with flame ionization/mass spectrometry detection and non-aqueous reversed-phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection.

Science.gov (United States)

Fanali, Chiara; Beccaria, Marco; Salivo, Simona; Tranchida, Peter; Tripodo, Giusy; Farnetti, Sara; Dugo, Laura; Dugo, Paola; Mondello, Luigi

2015-07-08

A chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non-aqueous reversed-phase high-performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two-dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high-resolution time-of-flight mass spectrometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Developmental effects of magnetic field (50 Hz) in combination with ionizing radiation and chemical teratogens.

Science.gov (United States)

Pafková, H; Jerábek, J; Tejnorová, I; Bednár, V

1996-11-01

The influence of a 50 Hz magnetic field (MF) on avian and mammalian embryogenesis, the MF level and vector, as well as the effect of exposure to MF (50 Hz, 10 mT) in combination with X-rays has been recently reported [2,3]. No significant alterations of chick or rat embryogenesis were found after repeated exposures to 50 Hz MF at 10 mT or 6 microT or with different vectors. However, X-ray chick embryotoxicity was significantly affected by repeated exposures of developing organisms to MF. A strong dependence of effect on the type of interaction was revealed. A decrease of X-ray induced teratogenicity was observed when MF preceded X-ray exposure (indirect interaction), while MF exposure applied immediately after X-ray radiation (direct interaction) non-significantly potentiated adverse developmental effects of ionizing radiation. This study deals with the effects of MF in combination with insulin or tetracycline. Exposure of chick embryos to MF influenced the sensitivity of embryonic morphogenetic systems to the subsequently administered chemical teratogens, insulin and/or tetracycline. A protective effect of MF was detected similarly as in the case of indirect interaction with ionizing radiation.

Ionizing and non-ionizing radiations

International Nuclear Information System (INIS)

1994-01-01

The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

The Use of Atmospheric Pressure Chemical Ionization Mass Spectrometry with High Performance Liquid Chromatography and Other Separation Techniques for Identification of Triacylglycerols

Czech Academy of Sciences Publication Activity Database

Řezanka, Tomáš; Sigler, Karel

2007-01-01

Roč. 3, - (2007), s. 252-271 ISSN 1573-4110 R&D Projects: GA ČR GA203/06/0219 Institutional research plan: CEZ:AV0Z50200510 Keywords : triacylglycerols * atmospheric presssure chemical ionization * mass spectrometry Subject RIV: EE - Microbiology, Virology Impact factor: 1.815, year: 2007

Like a Good Neighbor, NCI-Frederick Is There | Poster

Science.gov (United States)

The main campus of the National Cancer Institute at Frederick is an island of sorts: 68 acres of land that was once part of Fort Detrick. Accessing NCI property means passing through the Fort Detrick gates and crossing the post. While the campus is surrounded by the military installation, is protected by NIH police, and doesn’t allow the use of tobacco products, it is not a

NCI designated cancer center funding not influenced by organizational structure.

Science.gov (United States)

Wolfe, Margaret E; Yagoda, Daniel; Thurman, Paul W; Luna, Jorge M; Figg, William Douglas

2009-05-01

National Cancer Institutes (NCI) designated cancer centers use one of three organizational structures. The hypothesis of this study is that there are differences in the amount of annual NCI funding per faculty member based on a cancer center's organizational structure. The study also considers the impact of secondary factors (i.e., the existence of a clinical program, the region and the size of the city in which the cancer center is located) on funding and the number of Howard Hughes Medical Institute (HHMI) investigators at each cancer center. Of the 63 cancer centers, 44 use a matrix structure, 16 have a freestanding structure, and three have a Department of Oncology structure. Kruskal-Wallis tests reveal no statistically significant differences in the amount of funding per faculty member or the number of HHMI investigators between centers with a matrix, freestanding or Department of Oncology structure. Online research and telephone interviews with each cancer center were used to gather information, including: organizational structure, the presence of a clinical program, the number of faculty members, and the number of Howard Hughes Medical Institute investigators. Statistical tests were used to assess the impact which organizational structure has on the amount of funding per faculty member and number of HHMI investigators. While the results seem to suggest that the organizational structure of a given cancer center does not impact the amount of NCI funding or number of HHMI investigators which it attracts, the existence of this relationship is likely masked by the small sample size in this study. Further studies may be appropriate to examine the effect organizational structure has on other measurements which are relevant to cancer centers, such as quality and quantity of research produced.

Investigation of internalization and cytotoxicity of 125I-[Tyr3]-octreotide in NCI-H446 cell line

International Nuclear Information System (INIS)

Sun Junjie; Fan Wo; Xu Yujie; Zhang Youjiu; Zhu Ran; Hu Mingjiang

2004-01-01

Objective: To investigate the [Tyr 3 ]-octreotide (TOC) internalizing capacity of NCI-H446 cell line, and the cytotoxicity of 125 I-TOC in NCI-H446 cell line. To assess the therapeutic radiopharmaceutical potentiality of 125 I-TOC for the somatostatin receptor (SSTR) positive tumor. Methods: NCI-H446 cells were incubated together with 125 I-TOC for different periods of time, the amount of internalized 125 I-TOC and the 125 I-TOC bound on the cellular nucleus were detected with γ counter, respectively. The viability of the cells was analyzed by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay at different time points with various doses of 125 I-TOC, free 125 I and TOC. Results: 125 I-TOC was internalized into the nucleus and bound on the nucleus in a time-dependent manner. 125 I-TOC bound on the nucleus increased to the highest level at 24 h, the amount of nucleus bound 125 I-TOC at 24 h was 7 times higher than that at 0.5 h. Cytotoxicity of 125 I-TOC in SSTR positive NCI-H446 cells was also dose- and time-dependent. The supreme effect of cytotoxicity was found at 96 h with 74 kBq 125 I-TOC, the survival ratio of cells was reduced to (44.8 ± 7.2)%. Conclusions: 125 I-TOC can be internalized into SSTR positive cells mediated by SSTR. The NCI-H446 cells can be killed by Auger electron emitting from 125 I-TOC. Effect of cytotoxicity showed dose- and time-dependent

Best Performers Announced for the NCI-CPTAC DREAM Proteogenomics Computational Challenge | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

The National Cancer Institute (NCI) Clinical Proteomic Tumor Analysis Consortium (CPTAC) is pleased to announce that teams led by Jaewoo Kang (Korea University), and Yuanfang Guan with Hongyang Li (University of Michigan) as the best performers of the NCI-CPTAC DREAM Proteogenomics Computational Challenge. Over 500 participants from 20 countries registered for the Challenge, which offered $25,000 in cash awards contributed by the NVIDIA Foundation through its Compute the Cure initiative.

Mechanisms of chemical modification of neoplastic cell transformation by ionizing radiation

International Nuclear Information System (INIS)

Yang, T.C.; Tobias, C.A.

1985-01-01

During space travel, astronauts will be continuously exposed to ionizing radiation; therefore, it is necessary to minimize the radiation damage by all possible means. The authors' studies show that DMSO (when present during irradiation) can protect cells from being killed and transformed by X rays and that low concentration of DMSO can reduce the transformation frequency significantly when it is applied to cells, even many days after irradiation. The process of neoplastic cell transformation is a complicated one and includes at least two different stages: induction and expression. DMSO apparently can modify the radiation damage during both stages. There are several possible mechanisms for the DMSO effect: (1) changing the cell membrane structure and properties; (2) inducing cell differentiation by acting on DNA; and (3) scavanging free radicals in the cell. Recent studies with various chemical agents, e.g., 5-azacytidine, dexamethane, rhodamin-123, etc., indicate that the induction of cell differentiation by acting on DNA may be an important mechanism for the suppression of expression of neoplastic cell transformation by DMSO

Direct cortical hemodynamic mapping of somatotopy of pig nostril sensation by functional near-infrared cortical imaging (fNCI).

Science.gov (United States)

Uga, Minako; Saito, Toshiyuki; Sano, Toshifumi; Yokota, Hidenori; Oguro, Keiji; Rizki, Edmi Edison; Mizutani, Tsutomu; Katura, Takusige; Dan, Ippeita; Watanabe, Eiju

2014-05-01

Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique for the noninvasive monitoring of human brain activation states utilizing the coupling between neural activity and regional cerebral hemodynamics. Illuminators and detectors, together constituting optodes, are placed on the scalp, but due to the presence of head tissues, an inter-optode distance of more than 2.5cm is necessary to detect cortical signals. Although direct cortical monitoring with fNIRS has been pursued, a high-resolution visualization of hemodynamic changes associated with sensory, motor and cognitive neural responses directly from the cortical surface has yet to be realized. To acquire robust information on the hemodynamics of the cortex, devoid of signal complications in transcranial measurement, we devised a functional near-infrared cortical imaging (fNCI) technique. Here we demonstrate the first direct functional measurement of temporal and spatial patterns of cortical hemodynamics using the fNCI technique. For fNCI, inter-optode distance was set at 5mm, and light leakage from illuminators was prevented by a special optode holder made of a light-shielding rubber sheet. fNCI successfully detected the somatotopy of pig nostril sensation, as assessed in comparison with concurrent and sequential somatosensory-evoked potential (SEP) measurements on the same stimulation sites. Accordingly, the fNCI system realized a direct cortical hemodynamic measurement with a spatial resolution comparable to that of SEP mapping on the rostral region of the pig brain. This study provides an important initial step toward realizing functional cortical hemodynamic monitoring during neurosurgery of human brains. Copyright © 2014. Published by Elsevier Inc.

III. Penning ionization, associative ionization and chemi-ionization processes

International Nuclear Information System (INIS)

Cermak, V.

1975-01-01

Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

Science.gov (United States)

Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

2017-02-03

In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.

NCI and the Chinese Academy of Medical Sciences Sign Statement of Intent

Science.gov (United States)

Today the National Cancer Institute (NCI) and the Cancer Institute/Hospital of the Chinese Academy of Medical Sciences (CICAMS) signed a statement of intent to share an interest in fostering collaborative biomedical research in oncology and a common goal

Development and validation of a gas chromatography-negative chemical ionization tandem mass spectrometry method for the determination of ethyl glucuronide in hair and its application to forensic toxicology.

Science.gov (United States)

Kharbouche, Hicham; Sporkert, Frank; Troxler, Stéphanie; Augsburger, Marc; Mangin, Patrice; Staub, Christian

2009-08-01

Ethyl glucuronide (EtG) is a minor and direct metabolite of ethanol. EtG is incorporated into the growing hair allowing retrospective investigation of chronic alcohol abuse. In this study, we report the development and the validation of a method using gas chromatography-negative chemical ionization tandem mass spectrometry (GC-NCI-MS/MS) for the quantification of EtG in hair. EtG was extracted from about 30 mg of hair by aqueous incubation and purified by solid-phase extraction (SPE) using mixed mode extraction cartridges followed by derivation with perfluoropentanoic anhydride (PFPA). The analysis was performed in the selected reaction monitoring (SRM) mode using the transitions m/z 347-->163 (for the quantification) and m/z 347-->119 (for the identification) for EtG, and m/z 352-->163 for EtG-d(5) used as internal standard. For validation, we prepared quality controls (QC) using hair samples taken post mortem from 2 subjects with a known history of alcoholism. These samples were confirmed by a proficiency test with 7 participating laboratories. The assay linearity of EtG was confirmed over the range from 8.4 to 259.4 pg/mg hair, with a coefficient of determination (r(2)) above 0.999. The limit of detection (LOD) was estimated with 3.0 pg/mg. The lower limit of quantification (LLOQ) of the method was fixed at 8.4 pg/mg. Repeatability and intermediate precision (relative standard deviation, RSD%), tested at 4 QC levels, were less than 13.2%. The analytical method was applied to several hair samples obtained from autopsy cases with a history of alcoholism and/or lesions caused by alcohol. EtG concentrations in hair ranged from 60 to 820 pg/mg hair.

NCI's national environmental research data collection: metadata management built on standards and preparing for the semantic web

Science.gov (United States)

Wang, Jingbo; Bastrakova, Irina; Evans, Ben; Gohar, Kashif; Santana, Fabiana; Wyborn, Lesley

2015-04-01

National Computational Infrastructure (NCI) manages national environmental research data collections (10+ PB) as part of its specialized high performance data node of the Research Data Storage Infrastructure (RDSI) program. We manage 40+ data collections using NCI's Data Management Plan (DMP), which is compatible with the ISO 19100 metadata standards. We utilize ISO standards to make sure our metadata is transferable and interoperable for sharing and harvesting. The DMP is used along with metadata from the data itself, to create a hierarchy of data collection, dataset and time series catalogues that is then exposed through GeoNetwork for standard discoverability. This hierarchy catalogues are linked using a parent-child relationship. The hierarchical infrastructure of our GeoNetwork catalogues system aims to address both discoverability and in-house administrative use-cases. At NCI, we are currently improving the metadata interoperability in our catalogue by linking with standardized community vocabulary services. These emerging vocabulary services are being established to help harmonise data from different national and international scientific communities. One such vocabulary service is currently being established by the Australian National Data Services (ANDS). Data citation is another important aspect of the NCI data infrastructure, which allows tracking of data usage and infrastructure investment, encourage data sharing, and increasing trust in research that is reliant on these data collections. We incorporate the standard vocabularies into the data citation metadata so that the data citation become machine readable and semantically friendly for web-search purpose as well. By standardizing our metadata structure across our entire data corpus, we are laying the foundation to enable the application of appropriate semantic mechanisms to enhance discovery and analysis of NCI's national environmental research data information. We expect that this will further

ISOTOPE-DILUTION AMMONIA CHEMICAL-IONIZATION MASS FRAGMENTOGRAPHIC ANALYSIS OF URINARY 3-O-METHYLATED CATECHOLAMINE METABOLITES - RAPID SAMPLE CLEANUP BY DERIVATIZATION AND EXTRACTION OF LYOPHILIZED SAMPLES

NARCIS (Netherlands)

KEMA, IP; MEIBORG, G; NAGEL, GT; STOB, GJ; MUSKIET, FAJ

1993-01-01

We developed a method for simultaneous quantification of the urinary 3-O-methylated catecholamine metabolites 3-methoxytyramine, normetanephrine and metanephrine by stable isotope-dilution ammonia chemical ionization mass fragmentography. Prepurification of lyophilized samples was done by

Ressonàncies en plasmons sobre grafè

OpenAIRE

Alcaraz Iranzo, David

2014-01-01

Treball final de màster oficial fet en col·laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB) i Institut de Ciències Fotòniques (ICFO) [ANGLÈS] Graphene is used as a novel, versatile plasmonic material. The most common way to implement resonant light-plasmon coupling is to etch graphene into periodic nanostructures, which is invasive. Here, we study a non-invasive way to engineer graphene plasmon resonances, based on periodic doping profiles. The plasmon r...

Time-of-flight secondary ion mass spectrometry with energetic cluster ion impact ionization for highly sensitive chemical structure characterization

Energy Technology Data Exchange (ETDEWEB)

Hirata, K., E-mail: k.hirata@aist.go.jp [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Saitoh, Y.; Chiba, A.; Yamada, K.; Narumi, K. [Takasaki Advanced Radiation Research Institute (TARRI), Japan Atomic Energy Agency (JAEA), Takasaki, Gumma 370-1292 (Japan)

2013-11-01

Energetic cluster ions with energies of the order of sub MeV or greater were applied to time-of-flight (TOF) secondary ion (SI) mass spectrometry. This gave various advantages including enhancement of SIs required for chemical structure characterization and prevention of charging effects in SI mass spectra for organic targets. We report some characteristic features of TOF SI mass spectrometry using energetic cluster ion impact ionization and discuss two future applications of it.

Craig Reynolds, Ph.D., to Retire as NCI Associate Director for Frederick | Poster

Science.gov (United States)

On December 2, Craig Reynolds, Ph.D., director, Office of Scientific Operations, and NCI associate director for Frederick, will put the finishing touches on a 37-year career with the National Cancer Institute.

New Phone System Coming to NCI Campus at Frederick | Poster

Science.gov (United States)

By Travis Fouche and Trent McKee, Guest Writers Beginning in September, phones at the NCI Campus at Frederick will begin to be replaced, as the project to upgrade the current phone system ramps up. Over the next 16 months, the Information Systems Program (ISP) will be working with Facilities Maintenance and Engineering and Computer & Statistical Services to replace the current

Identification of volatile and semivolatile compounds in chemical ionization GC-MS using a mass-to-structure (MTS) Search Engine with integral isotope pattern ranking.

Science.gov (United States)

Liao, Wenta; Draper, William M

2013-02-21

The mass-to-structure or MTS Search Engine is an Access 2010 database containing theoretical molecular mass information for 19,438 compounds assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. This database, which contains no experimental mass spectral data, was developed as an aid to identification of compounds in atmospheric pressure ionization (API)-LC-MS. This paper describes a powerful upgrade to this database, a fully integrated utility for filtering or ranking candidates based on isotope ratios and patterns. The new MTS Search Engine is applied here to the identification of volatile and semivolatile compounds including pesticides, nitrosoamines and other pollutants. Methane and isobutane chemical ionization (CI) GC-MS spectra were obtained from unit mass resolution mass spectrometers to determine MH(+) masses and isotope ratios. Isotopes were measured accurately with errors of Search Engine and details performance testing with over 50 model compounds.

Universal imaging: Dissociative ionization of polyatomic molecules, chemical dynamics beamline 9.0.2

Energy Technology Data Exchange (ETDEWEB)

Ahmed, M.; Chen, D.; Suits, A.G. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

1997-04-01

A third endstation was recently added to the Chemical Dynamics beamline, designed to exploit the high flux broadband undulator light for a range of studies of reactive scattering, photochemistry and photoionization processes using time-of-flight mass spectroscopy coupled with position-sensitive detection. Two molecular beam sources are fixed at right angles, with the undulator light, or laser beams, intersecting the molecular beams at 45{degrees}. To date, beamline experiments have included a study of dissociative photoionization of a variety of molecules including N{sub 2}O and SF{sub 6}. In this mode, a single molecular beam source is used, with the tunable undulator light inducing, in SF{sub 6} for example, the process SF{sub 6} {r_arrow} SF{sub 6}{sup +} + e{sup {minus}} {r_arrow} SF{sub 5}{sup +} + F + e{sup {minus}}. The SF{sub 5}{sup +} ions are accelerated up the flight tube, mass selected and detected as a function of position on a phosphor screen viewed by a CCD camera. The position directly reveals the recoil speed (or translational energy release) and angular distribution for the dissociative ionization process. Furthermore, this measurement is obtained for all recoil speeds and angles simultaneously. Such detailed angular information has not previously been obtained for dissociative ionization processes; typically ion time-of-flight profiles are deconvoluted to yield rough insight into the angular distributions. The recorded image is actually a 2-dimensional projection of the nascent 3-dimensional velocity distribution, but established tomographic techniques enable the authors to reconstruct the 3-D distribution.

Methods of direct (non-chromatographic) quantification of body metabolites utilizing chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Mee, J.M.L.

1978-01-01

For quantitative determination of known metabolites from the biological sample by direct chemical ionization mass spectrometry (CI-MS), the method of internal standard using stable isotopically labelled analogs appears to be the method of choice. In the case where stable isotope ratio determinations could not be applied, and alternative quantification can be achieved using non-labelled external or internal standards and a calibration curve (sum of peak height per a given number of scans versus concentration). The technique of computer monitoring permits display and plotting of ion current profiles (TIC and SIC) or spectra per a given number of scans or a given range of mass per charge. Examples are given in areas of clinical application and the quantitative data show very good agreement with the conventional chromatographic measurements. (Auth.)

Free radical production by high energy shock waves--comparison with ionizing irradiation.

Science.gov (United States)

Morgan, T R; Laudone, V P; Heston, W D; Zeitz, L; Fair, W R

1988-01-01

Fricke chemical dosimetry is used as an indirect measure of the free radical production of ionizing irradiation. We adapted the Fricke ferrous sulfate radiation dosimeter to examine the chemical effects of high energy shock waves. Significant free radical production was documented. The reaction was dose dependent, predictably increased by acoustic impedance, but curvilinear. A thousand shocks at 18 kilovolts induced the same free radical oxidation as 1100 rad cobalt-60 gamma ionizing irradiation, increasing to 2900 rad in the presence of an air-fluid zone of acoustic impedance. The biological effect of these free radicals was compared to that of cobalt-60 ionizing irradiation by measuring the affect on Chinese hamster cells by clonogenic assay. While cobalt-60 irradiation produced a marked decrease in clonogenic survivors, little effect was noted with high energy shock waves. This suggested that the chemical effects produced by shock waves were either absent or attenuated in the cells, or were inherently less toxic than those of ionizing irradiation.

A Gene-Based Prognostic for Hepatocellular Carcinoma Patient Response to Adjuvant Transcatheter Arterial Chemoembolization | NCI Technology Transfer Center | TTC

Science.gov (United States)

The gold standard of care for hepatocellular carcinoma patients with intermediate- to locally advanced tumors is transcatheter arterial chemoembolization (TACE), a procedure whereby the tumor is targeted both with local chemotherapy and restriction of local blood supply. NCI scientists have identified a 14-gene signature predictive of response to TACE, and NCI seeks licensees or co-development partners to develop the technology toward commercialization.

Chemical separation of plutonium from air filters and preparation of filaments for resonance ionization mass spectroscopy

International Nuclear Information System (INIS)

Eberhardt, K.; Erdmann, N.; Funk, H.; Herrmann, G.; Naehler, A.; Passler, G.; Trautmann, N.; Urban, F.

1995-01-01

Resonance ionization mass spectroscopy (RIMS) is used for the determination of plutonium in environmental samples. A chemical procedure based on an ion-exchange technique for the separation of plutonium from a polycarbonate filter is described. The overall yield is about 60% as determined by α-particle spectroscopy. A technique for the subsequent preparation of samples for RIMS measurements is developed. Plutonium is electrode-posited as hydroxide and covered with a thin metallic layer. While heating such a sandwich filament the plutonium hydroxide is reduced to the metal and an atomic beam is evaporated from the surface, as required for RIMS. copyright American Institute of Physics 1995

Cluster chemical ionization for improved confidence level in sample identification by gas chromatography/mass spectrometry.

Science.gov (United States)

Fialkov, Alexander B; Amirav, Aviv

2003-01-01

Upon the supersonic expansion of helium mixed with vapor from an organic solvent (e.g. methanol), various clusters of the solvent with the sample molecules can be formed. As a result of 70 eV electron ionization of these clusters, cluster chemical ionization (cluster CI) mass spectra are obtained. These spectra are characterized by the combination of EI mass spectra of vibrationally cold molecules in the supersonic molecular beam (cold EI) with CI-like appearance of abundant protonated molecules, together with satellite peaks corresponding to protonated or non-protonated clusters of sample compounds with 1-3 solvent molecules. Like CI, cluster CI preferably occurs for polar compounds with high proton affinity. However, in contrast to conventional CI, for non-polar compounds or those with reduced proton affinity the cluster CI mass spectrum converges to that of cold EI. The appearance of a protonated molecule and its solvent cluster peaks, plus the lack of protonation and cluster satellites for prominent EI fragments, enable the unambiguous identification of the molecular ion. In turn, the insertion of the proper molecular ion into the NIST library search of the cold EI mass spectra eliminates those candidates with incorrect molecular mass and thus significantly increases the confidence level in sample identification. Furthermore, molecular mass identification is of prime importance for the analysis of unknown compounds that are absent in the library. Examples are given with emphasis on the cluster CI analysis of carbamate pesticides, high explosives and unknown samples, to demonstrate the usefulness of Supersonic GC/MS (GC/MS with supersonic molecular beam) in the analysis of these thermally labile compounds. Cluster CI is shown to be a practical ionization method, due to its ease-of-use and fast instrumental conversion between EI and cluster CI, which involves the opening of only one valve located at the make-up gas path. The ease-of-use of cluster CI is analogous

It’s Easy to Recycle at NCI at Frederick | Poster

Science.gov (United States)

From 2013 through the first quarter of 2018, NCI at Frederick has recycled over 1,667 tons of material, while incinerating or landfilling over 4,273 tons of trash. This earns us a recycling rate close to 28 percent, which is below the national average of 32 percent, according to the Environmental Protection Agency, and well below our goal of 50 percent. (These numbers only

Shrinking droplets in electrospray ionization and their influence on chemical equilibria.

Science.gov (United States)

Wortmann, Arno; Kistler-Momotova, Anna; Zenobi, Renato; Heine, Martin C; Wilhelm, Oliver; Pratsinis, Sotiris E

2007-03-01

We investigated how chemical equilibria are affected by the electrospray process, using simultaneous in situ measurements by laser-induced fluorescence (LIF) and phase Doppler anemometry (PDA). The motivation for this study was the increasing number of publications in which electrospray ionization mass spectrometry is used for binding constant determination. The PDA was used to monitor droplet size and velocity, whereas LIF was used to monitor fluorescent analytes within the electrospray droplets. Using acetonitrile as solvent, we found an average initial droplet diameter of 10 microm in the electrospray. The PDA allowed us to follow the evolution of these droplets down to a size of 1 microm. Rhodamine B-sulfonylchloride was used as a fluorescent analyte within the electrospray. By spatially resolved LIF it was possible to probe the dimerization equilibrium of this dye. Measurements at different spray positions showed no influence of the decreasing droplet size on the monomer-dimer equilibrium. However, with the fluorescent dye pair DCM and oxazine 1 it was shown that a concentration increase does occur within electrosprayed droplets, using fluorescence resonance energy transfer as a probe for the average pair distance.

Modern state of the application of ionizing radiation for protection of environment. 1. Ionizing radiation sources. Purification of natural and drinking water (review)

International Nuclear Information System (INIS)

Pikaev, AK.

2000-01-01

Review of modern state of the application of ionizing radiations for protection of environment and natural and drinking water purification is presented. Building of installations with electron accelerators with summarized power of beam ∼0.6 MW signifies that application of ionizing radiation for ecological needs increase. It is pointed out that extensible application of electron accelerators is explained by their safety and efficiency as compared with gamma-sources. New information about ionizing radiation sources, radiation-chemical purification of polluted natural and drinking water, mechanisms of processes taking place during treatment by ionizing radiations are generalized [ru

Tendències en el disseny metodològic de recerca sobre l’avaluació de competències a l’educació superior

Directory of Open Access Journals (Sweden)

Karina Angélica Villegas Sandoval

2017-01-01

Full Text Available L’article té com a finalitat descriure i analitzar les metodologies d'investigació utilitzades per estudis recents que aborden el tema de l’avaluació per competències a l’educació superior i la formació docent, per tal de detectar les tendències en el disseny metodològic i orientar futurs projectes d'investigació sobre aquest tema. El mètode de treball que s'ha seguit per dur a terme aquest estudi és l’anàlisi de contingut de 22 documents trobats a Dialnet. Els resultats mostren que les investigacions que tracten el tema assenyalat han anat en augment en els últims tretze anys, i es destaca el canvi de metodologia utilitzada, amb dissenys majoritàriament descriptius i avaluatius. Al seu torn, però, crida l'atenció que un gran nombre d'estudis no expliquen ni el mètode ni el disseny d'investigació que han aplicat. Es conclou que és important que les investigacions presentin un apartat que al·ludeixi al disseny metodològic a fi d’afavorir la comprensió del lector dels processos d'indagació que s'han dut a terme.

Inorganic trace analysis by laser ionization mass spectrometry

International Nuclear Information System (INIS)

Becker, S.; Dietze, H.J.

1991-01-01

Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytic method with a wide coverage. In the LIMS the sample material is evaporated and ionized by means of a focused pulsed laser beam in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The formed ions are separated according to mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments, and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

Laser ionization mass spectrometry in inorganic trace analysis

International Nuclear Information System (INIS)

Becker, J.S.; Dietze, H.J.

1992-01-01

Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytical method. With the LIMS technique the sample material is evaporated and ionized by means of a focused pulsed laser in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The ions formed are separated according to their mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

Determination of clebopride in plasma by capillary gas chromatography-negative-ion chemical ionization mass spectrometry.

Science.gov (United States)

Robinson, P R; Jones, M D; Maddock, J

1988-11-18

A procedure for the analysis of clebopride in plasma using capillary gas chromatography-negative-ion chemical ionization mass spectrometry has been developed. Employing an ethoxy analogue as internal standard, the two compounds were extracted from basified plasma using dichloromethane. Subsequent reaction with heptafluorobutyryl imidazole produced volatile monoheptafluorobutyryl derivatives whose ammonia negative-ion mass spectra proved ideal for selected-ion monitoring. The recovery of clebopride from plasma at 0.536 nmol/l was found to be 85.5 +/- 0.9% (n = 3) whilst measurement down to 0.268 nmol/l was possible with a coefficient of variation of 7.9%. Plasma levels of the compound are reported in two volunteers following ingestion of 1 mg of clebopride as the malate salt.

Are clusters important in understanding the mechanisms in atmospheric pressure ionization? Part 1: Reagent ion generation and chemical control of ion populations.

Science.gov (United States)

Klee, Sonja; Derpmann, Valerie; Wißdorf, Walter; Klopotowski, Sebastian; Kersten, Hendrik; Brockmann, Klaus J; Benter, Thorsten; Albrecht, Sascha; Bruins, Andries P; Dousty, Faezeh; Kauppila, Tiina J; Kostiainen, Risto; O'Brien, Rob; Robb, Damon B; Syage, Jack A

2014-08-01

It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region.

Program Spotlight: Ground Broken for NCI-supported Cancer Treatment Center in Puerto Rico

Science.gov (United States)

Dr. Sanya A. Springfield represented NCI at the groundbreaking ceremonies for the University of Puerto Rico (UPR) cancer hospital. In her remarks, she acknowledged the driving force behind this development is the UPR and the MD Anderson Cancer Center partnership.

Softball Games Bring NCI and Leidos Biomed Employees Together | Poster

Science.gov (United States)

NCI and Leidos Biomed employees took to the fields at Nallin Pond for the third annual slow-pitch softball games on August 26. The series attracted 54 employees who were divided into four teams, Red, Blue, Gray, and White, and they were cheered on by about 40 enthusiastic spectators. In the first set of games, the Gray team defeated the Blue team, 15–8, and the White team

Molecular single photon double K-shell ionization

International Nuclear Information System (INIS)

Penent, F.; Nakano, M.; Tashiro, M.; Grozdanov, T.P.; Žitnik, M.; Carniato, S.; Selles, P.; Andric, L.; Lablanquie, P.; Palaudoux, J.; Shigemasa, E.; Iwayama, H.; Hikosaka, Y.; Soejima, K.; Suzuki, I.H.; Kouchi, N.; Ito, K.

2014-01-01

We have studied single photon double K-shell ionization of small molecules (N 2 , CO, C 2 H 2n (n = 1–3), …) and the Auger decay of the resulting double core hole (DCH) molecular ions thanks to multi-electron coincidence spectroscopy using a magnetic bottle time-of-flight spectrometer. The relative cross-sections for single-site (K −2 ) and two-site (K −1 K −1 ) double K-shell ionization with respect to single K-shell (K −1 ) ionization have been measured that gives important information on the mechanisms of single photon double ionization. The spectroscopy of two-site (K −1 K −1 ) DCH states in the C 2 H 2n (n = 1–3) series shows important chemical shifts due to a strong dependence on the C-C bond length. In addition, the complete cascade Auger decay following single site (K −2 ) ionization has been obtained

Spatially resolved thermal desorption/ionization coupled with mass spectrometry

Science.gov (United States)

Jesse, Stephen; Van Berkel, Gary J; Ovchinnikova, Olga S

2013-02-26

A system and method for sub-micron analysis of a chemical composition of a specimen are described. The method includes providing a specimen for evaluation and a thermal desorption probe, thermally desorbing an analyte from a target site of said specimen using the thermally active tip to form a gaseous analyte, ionizing the gaseous analyte to form an ionized analyte, and analyzing a chemical composition of the ionized analyte. The thermally desorbing step can include heating said thermally active tip to above 200.degree. C., and positioning the target site and the thermally active tip such that the heating step forms the gaseous analyte. The thermal desorption probe can include a thermally active tip extending from a cantilever body and an apex of the thermally active tip can have a radius of 250 nm or less.

Vaccines for HIV | NCI Technology Transfer Center | TTC

Science.gov (United States)

The development of an effective HIV vaccine has been an ongoing area of research. The high variability in HIV-1 virus strains has represented a major challenge in successful development. Ideally, an effective candidate vaccine would provide protection against the majority of clades of HIV. Two major hurdles to overcome are immunodominance and sequence diversity. This vaccine utilizes a strategy for overcoming these two issues by identifying the conserved regions of the virus and exploiting them for use in a targeted therapy. NCI seeks licensees and/or research collaborators to commercialize this technology, which has been validated in macaque models.

Mass spectral analysis of N-oxides of Chemical Weapons Convention related aminoethanols under electrospray ionization conditions.

Science.gov (United States)

Sridhar, L; Karthikraj, R; Murty, M R V S; Raju, N Prasada; Vairamani, M; Prabhakar, S

2011-02-28

N,N'-Dialkylaminoethanols are the hydrolyzed products or precursors of chemical warfare agents such as V-agents and nitrogen mustards, and they are prone to undergo oxidation in environmental matrices or during decontamination processes. Consequently, screening of the oxidized products of aminoethanols in aqueous samples is an important task in the verification of chemical weapons convention-related chemicals. Here we report the successful characterization of the N-oxides of N,N'-dialkylaminoethanols, alkyl diethanolamines, and triethanolamine using positive ion electrospray ionization mass spectrometry. The collision-induced dissociation (CID) spectra of the [M+H](+) and [M+Na](+) ions show diagnostic product ions that enable the unambiguous identification of the studied N-oxides, including those of isomeric compounds. The proposed fragmentation pathways are supported by high-resolution mass spectrometry data and product/precursor ion spectra. The CID spectra of [M+H](+) ions included [MH-CH(4)O(2)](+) as the key product ion, in addition to a distinctive alkene loss that allowed us to recognize the alkyl group attached to the nitrogen. The [M+Na](+) ions show characteristic product ions due to the loss of groups (R) attached to nitrogen either as a radical (R) or as a molecule [R+H or (R-H)] after hydrogen migration. Copyright © 2011 John Wiley & Sons, Ltd.

Monitoring presence of chemical agents

International Nuclear Information System (INIS)

Preston, J.M.

1984-01-01

The specification describes a case for use with a hand-portable chemical agent detector for continuously monitoring an atmosphere for the presence of predetermined chemical agents. The detector having means for ionizing air samples and providing at an output terminal electrical signals representative of the mobility spectrum of ionized chemical vapours produced by the ionizing means. The case comprises means for defining a chamber in the case for supporting and removably enclosing the detector, means for communicating ambient atmosphere to the chamber, electrical circuit means in the case, the circuit means being adapted to be detachably connected to the detector output terminal when the detector is positioned in the chamber and being responsive to the electrical signals for producing an alarm signal when the signals detect a chemical agent concentration in the atmosphere exceeding a predetermined concentration level, and alarm means responsive to the alarm signal. (author)

Health effects of ionizing radiation

International Nuclear Information System (INIS)

Pathak, B.

1989-12-01

Ionizing radiation is energy that travels through space as electromagnetic waves or a stream of fast moving particles. In the workplace, the sources of ionizing radiation are radioactive substances, nuclear power plants, x-ray machines and nuclear devices used in medicine, research and industry. Commonly encountered types of radiation are alpha particles, beta particles and gamma rays. Alpha particles have very little penetrating power and pose a risk only when the radioactive substance is deposited inside the body. Beta particles are more penetrating than alpha particles and can penetrate the outer body tissues causing damage to the skin and the eyes. Gamma rays are highly penetrating and can cause radiation damage to the whole body. The probability of radiation-induced disease depends on the accumulated amount of radiation dose. The main health effects of ionizing radiation are cancers in exposed persons and genetic disorders in the children, grandchildren and subsequent generations of the exposed parents. The fetus is highly sensitive to radiation-induced abnormalities. At high doses, radiation can cause cataracts in the eyes. There is no firm evidence that ionizing radiation causes premature aging. Radiation-induced sterility is highly unlikely for occupational doses. The data on the combined effect of ionizing radiation and other cancer-causing physical and chemical agents are inconclusive

NCI's High Performance Computing (HPC) and High Performance Data (HPD) Computing Platform for Environmental and Earth System Data Science

Science.gov (United States)

Evans, Ben; Allen, Chris; Antony, Joseph; Bastrakova, Irina; Gohar, Kashif; Porter, David; Pugh, Tim; Santana, Fabiana; Smillie, Jon; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

2015-04-01

The National Computational Infrastructure (NCI) has established a powerful and flexible in-situ petascale computational environment to enable both high performance computing and Data-intensive Science across a wide spectrum of national environmental and earth science data collections - in particular climate, observational data and geoscientific assets. This paper examines 1) the computational environments that supports the modelling and data processing pipelines, 2) the analysis environments and methods to support data analysis, and 3) the progress so far to harmonise the underlying data collections for future interdisciplinary research across these large volume data collections. NCI has established 10+ PBytes of major national and international data collections from both the government and research sectors based on six themes: 1) weather, climate, and earth system science model simulations, 2) marine and earth observations, 3) geosciences, 4) terrestrial ecosystems, 5) water and hydrology, and 6) astronomy, social and biosciences. Collectively they span the lithosphere, crust, biosphere, hydrosphere, troposphere, and stratosphere. The data is largely sourced from NCI's partners (which include the custodians of many of the major Australian national-scale scientific collections), leading research communities, and collaborating overseas organisations. New infrastructures created at NCI mean the data collections are now accessible within an integrated High Performance Computing and Data (HPC-HPD) environment - a 1.2 PFlop supercomputer (Raijin), a HPC class 3000 core OpenStack cloud system and several highly connected large-scale high-bandwidth Lustre filesystems. The hardware was designed at inception to ensure that it would allow the layered software environment to flexibly accommodate the advancement of future data science. New approaches to software technology and data models have also had to be developed to enable access to these large and exponentially

Biopositive Effects of Ionizing Radiation?

International Nuclear Information System (INIS)

Broda, E.

1972-01-01

This paper was written for a talk given by E. Broda in Vienna for an event organised by the chemical physical society, the Austrian biochemical society and the Austrian biophysical society in December 1972. In this paper Broda analyses the question of biopositive effects of ionizing radiation. (nowak)

Effects of ionizing radiation on plastic food packaging materials: a review. 1. Chemical and physical changes

International Nuclear Information System (INIS)

Buchalla, R.; Schuttler, C.; Bögl, K.W.

1993-01-01

Irradiation of prepackaged food causes chemical and physical changes in plastic packaging materials. The effects of ionizing radiation on these materials have been studied for almost 40 years; the respective literature is reviewed to provide the basis for a safety evaluation of plastics for use in food irradiation. Permeability of plastic films is generally not affected; deterioration of mechanical properties, that may occur with certain polymers, can usually be controlled with adequate stabilizers; and changes in infrared and UV/VIS spectra are slight at food irradiation doses. Gaseous radiolysis products include hydrogen, methane, CO 2 , CO, hydrocarbons, and for chlorine-containing polymers, hydrogen chloride. A range of volatile products, mainly hydrocarbons, alcohols, aldehydes, ketones, and carboxylic acids, has been characterized for low density polyethylene and polypropylene, other important materials, e.g., polystyrene and poly(vinyl chloride), are less well-investigated. Comparatively little is known on the effect of irradiation on multilayer structures. Radiation-induced changes are shown to depend on the chemical structure of the polymer, on the composition (additives) and processing history of the plastic, and on the irradiation conditions

Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

Science.gov (United States)

Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

2013-11-01

In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. Copyright © 2013 John Wiley & Sons, Ltd.

NCI and the Chinese National Cancer Center pursue new collaborations in cancer research

Science.gov (United States)

CGH Director, Dr. Ted Trimble, and East Asia Program Director, Dr. Ann Chao, traveled to Beijing with Mr. Matthew Brown from the Department of Health and Human Services Office of Global Affairs to attend the Joint Meeting of the NCC and the U.S. NCI.

Ratio Based Biomarkers for the Prediction of Cancer Survival | NCI Technology Transfer Center | TTC

Science.gov (United States)

The NCI seeks licensees or co-development partners for this technology, which describes compositions, methods and kits for identifying, characterizing biomolecules expressed in a sample that are associated with the presence, the development, or progression of cancer.

Vibronic coupling in ionized organic molecules: structural distortions and chemical reactions

International Nuclear Information System (INIS)

Williams, Ffrancon

2003-01-01

Ionized organic molecules (radical cations) in radiation chemistry are liable to undergo vibronic coupling whenever there is a relatively small energy gap (∼0.5-1.5 eV) between their ground and excited states. As a result of this mixing, the force constant for the symmetry-allowed vibrational mode that couples these states is lowered in the ground state of the radical cation so that deformation can take place more easily along this specific mode. This pseudo-Jahn-Teller effect can then result in a permanent structural distortion of the radical cation relative to the symmetry of the parent neutral molecule. It can also bring about an energetically favored pathway for a facile chemical rearrangement along a reaction coordinate defined by the coupling mode. Examples taken from matrix-isolation studies are used to illustrate these dramatic consequences of vibronic coupling in radical cations. Thus, the bicyclo[2.2.2]oct-2-ene and tetramethylurea radical cations are found to have twisted structures departing from the C 2v symmetry of their parent molecules, while the oxirane and bicyclo[1.1.1]pentane radical cations undergo ring-opening rearrangements along reaction coordinates that correspond to the deformational modes predicted by the pseudo-Jahn-Teller effect

Anàlisi forense d'evidències digitals

OpenAIRE

Bonachera López, Esteban

2014-01-01

L'objectiu principal d'aquest projecte consisteix en la realització de l'anàlisi forense del disc dur i de la memòria RAM d'un ordinador personal, en concret un Netbook, vinculat a una possible conducta delictiva. També s'inclou en l'anàlisi una base de dades del conegut programari WhatsApp extreta d'un smartphone. Per realitzar aquesta tasca s'utilitzaran eines específiques per localitzar les evidències digitals que puguin demostrar els presumptes delictes. El objetivo principal de este p...

Mission & Role | NCI Technology Transfer Center | TTC

Science.gov (United States)

The NCI TTC serves as the focal point for implementing the Federal Technology Transfer Act to utilize patents as incentive for commercial development of technologies and to establish research collaborations and licensing among academia, federal laboratories, non-profit organizations, and industry. The TTC supports technology development activities for the National Cancer Institute and nine other NIH Institutes and Centers. TTC staff negotiate co-development agreements and licenses with universities, non-profit organizations, and pharmaceutical and biotechnology companies to ensure compliance with Federal statutes, regulations and the policies of the National Institutes of Health. TTC also reviews employee invention reports and makes recommendations concerning filing of domestic and foreign patent applications. | [google6f4cd5334ac394ab.html

Variations in Mre11/Rad50/Nbs1 status and DNA damage-induced S-phase arrest in the cell lines of the NCI60 panel

Directory of Open Access Journals (Sweden)

Eastman Alan

2011-05-01

Full Text Available Abstract Background The Mre11/Rad50/Nbs1 (MRN complex is a regulator of cell cycle checkpoints and DNA repair. Defects in MRN can lead to defective S-phase arrest when cells are damaged. Such defects may elicit sensitivity to selected drugs providing a chemical synthetic lethal interaction that could be used to target therapy to tumors with these defects. The goal of this study was to identify these defects in the NCI60 panel of cell lines and identify compounds that might elicit selective cytotoxicity. Methods We screened the NCI60 panel in search of cell lines that express low levels of MRN proteins, or that fail to arrest in S-phase in response to the topisomerase I inhibitor SN38. The NCI COMPARE program was used to discover compounds that preferentially target cells with these phenotypes. Results HCT116 cells were initially identified as defective in MRN and S phase arrest. Transfection with Mre11 also elevated Rad50 and Nbs1, and rescued the defective S-phase arrest. Cells of the NCI60 panel exhibited a large range of protein expression but a strong correlation existed between Mre11, Rad50 and Nbs1 consistent with complex formation determining protein stability. Mre11 mRNA correlated best with protein level suggesting it was the primary determinant of the overall level of the complex. Three other cell lines failed to arrest in response to SN38, two of which also had low MRN. However, other cell lines with low MRN still arrested suggesting low MRN does not predict an inability to arrest. Many compounds, including a family of benzothiazoles, correlated with the failure to arrest in S phase. The activity of benzothiazoles has been attributed to metabolic activation and DNA alkylation, but we note several cell lines in which sensitivity does not correlate with metabolism. We propose that the checkpoint defect imposes an additional mechanism of sensitivity on cells. Conclusions We have identified cells with possible defects in the MRN complex

Variations in Mre11/Rad50/Nbs1 status and DNA damage-induced S-phase arrest in the cell lines of the NCI60 panel

International Nuclear Information System (INIS)

Garner, Kristen M; Eastman, Alan

2011-01-01

The Mre11/Rad50/Nbs1 (MRN) complex is a regulator of cell cycle checkpoints and DNA repair. Defects in MRN can lead to defective S-phase arrest when cells are damaged. Such defects may elicit sensitivity to selected drugs providing a chemical synthetic lethal interaction that could be used to target therapy to tumors with these defects. The goal of this study was to identify these defects in the NCI60 panel of cell lines and identify compounds that might elicit selective cytotoxicity. We screened the NCI60 panel in search of cell lines that express low levels of MRN proteins, or that fail to arrest in S-phase in response to the topisomerase I inhibitor SN38. The NCI COMPARE program was used to discover compounds that preferentially target cells with these phenotypes. HCT116 cells were initially identified as defective in MRN and S phase arrest. Transfection with Mre11 also elevated Rad50 and Nbs1, and rescued the defective S-phase arrest. Cells of the NCI60 panel exhibited a large range of protein expression but a strong correlation existed between Mre11, Rad50 and Nbs1 consistent with complex formation determining protein stability. Mre11 mRNA correlated best with protein level suggesting it was the primary determinant of the overall level of the complex. Three other cell lines failed to arrest in response to SN38, two of which also had low MRN. However, other cell lines with low MRN still arrested suggesting low MRN does not predict an inability to arrest. Many compounds, including a family of benzothiazoles, correlated with the failure to arrest in S phase. The activity of benzothiazoles has been attributed to metabolic activation and DNA alkylation, but we note several cell lines in which sensitivity does not correlate with metabolism. We propose that the checkpoint defect imposes an additional mechanism of sensitivity on cells. We have identified cells with possible defects in the MRN complex and S phase arrest, and a series of compounds that may

Comparative study of fourteen alkaloids from Uncaria rhynchophylla hooks and leaves using HPLC-diode array detection-atmospheric pressure chemical ionization/MS method.

Science.gov (United States)

Qu, Jialin; Gong, Tianxing; Ma, Bin; Zhang, Lin; Kano, Yoshihiro; Yuan, Dan

2012-01-01

The purpose of the study is to compare alkaloid profile of Uncaria rhynchophylla hooks and leaves. Ten oxindole alkaloids and four glycosidic indole alkaloids were identified using HPLC-diode array detection (DAD) or LC-atmospheric pressure chemical ionization (APCI)-MS method, and a HPLC-UV method for simultaneous quantification of major alkaloids was validated. The hooks are characterized by high levels of four oxindole alkaloids rhynchophylline (R), isorhynchophylline (IR), corynoxeine (C) and isocorynoxeine (IC), while the leaves contained high level of two glycosidic indole alkaloids vincoside lactam (VL) and strictosidine (S). The presented methods have proven its usefulness in chemical characterization of U. rhynchophylla hooks and leaves.

NCI at Frederick Employees Receive Awards at the Spring Research Festival | Poster

Science.gov (United States)

NCI and Frederick National Laboratory staff members were among those honored at the Spring Research Festival Awards Ceremony on May 28. The ceremony was the culmination of the festival, which was sponsored by the National Interagency Confederation for Biological Research (NICBR), May 4–7. Maj. Gen. Brian Lein, commanding general, U.S. Army Medical Research and Materiel Command

Silica-Coated Nanodiamonds for Imaging and Delivery of Therapeutic Agents | NCI Technology Transfer Center | TTC

Science.gov (United States)

The NCI Radiation Oncology Branch and the NHLBI Laboratory of Single Molecule Biophysics seek parties to co-develop fluorescent nanodiamonds for use as in vivo and in vitro optical tracking probes toward commercialization.

76 FR 14034 - Proposed Collection; Comment Request; NCI Cancer Genetics Services Directory Web-Based...

Science.gov (United States)

2011-03-15

... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Proposed Collection; Comment Request; NCI Cancer Genetics Services Directory Web-Based Application Form and Update Mailer Summary: In... Cancer Genetics Services Directory Web-based Application Form and Update Mailer. [[Page 14035

Chemical ionization mass spectrometry of indol-3yl-acetic acid and cis-abscisic acid: evaluation of negative ion detection and quantification of cis-abscisic acid in growing maize roots

International Nuclear Information System (INIS)

Rivier, L.; Saugy, M.

1986-01-01

Mass spectra of the derivatives of indol-3yl-acetic acid and cis-abscisic acid were obtained in electron impact and chemical ionization positive ion and negative ion modes. The respective merits of methane, isobutane, and ammonia as reagent gases for structure determination and sensitive detection were compared using the methyl esters. From one to 10 fluorine atoms were attached to IAA to improve the electron-capturing properties of the molecule. The best qualitative information was obtained when using positive ion chemical ionization with methane. However, the most sensitive detection, with at least two ions per molecule, was achieved by electron impact on the IAA-HFB-ME derivative and by negative ion chemical ionization with NH 3 on the ABA-methyl ester derivative. p ]Quantitative analyses of ABA in different parts of maize (Zea mays cv. LG 11) root tips were performed by the latter technique. It was found that the cap and apex contained less ABA than the physiologically older parts of the root such as the elongation zone and the more differentiated tissues. This technique was also used to show a relation between maize root growth and the endogenous ABA level of the elongation zone and root tip: there is more ABA in the slowly growing roots than in the rapidly growing ones. (author)

THE NCI STUDIES ON RADIATION DOSES AND CANCER RISKS IN THE MARSHALL ISLANDS ASSOCIATED WITH EXPOSURE TO RADIOACTIVE FALLOUT

OpenAIRE

Simon, Steven L.

2012-01-01

The U.S. National Cancer Institute (NCI, National Institutes of Health) was requested by the U.S. Congress in 2004 to assess the number of radiation-related illnesses to be expected among the people of the Marshall Islands from nuclear tests conducted there during 1946-1958. A thorough analysis conducted by the NCI concluded that 20 of the 66 nuclear devices tested in or near the Marshall Islands resulted in measurable fallout deposition on one or more of the inhabited atolls of the Marshall ...

Chromosome aberrations in peripheral blood lymphocytes in subjects occupationally exposed to ionizing radiation or chemical clastogens

International Nuclear Information System (INIS)

Lalic, H.; Radosevic-Stasic, B.

2002-01-01

To get an insight into genotoxic risk in some occupations, in this study the chromosome aberration analysis of peripheral blood lymphocytes was made in 20 physicians and nurses exposed to a low dose of ionizing radiation in a hospital, 12 individuals working with X-rays in a cement factory and 19 technicians working with some chemical toxic agents in the laboratories of a medical school. The control group consisted of 14 sex- and age-matched unexposed persons living in the same district area. The data showed that the total number of chromosome aberrations in 200 scored metaphases in all examined groups were almost the same and inside the low-permitted values. In hospital workers, however, the percentage of acentric and dicentric fragments (1.63 ± 0.28 vs 0.31 ± 0.21 and 0.47 ± 0.18 vs 0.0, respectively) increased predominantly in contrast to cement-factory employees and laboratory workers, where a higher incidence of minutes (0.58 ± 0.19 vs 0.31 ± 0.2) or gaps (2.21 ± 0.37 vs 1.15 ± 1.15) was noticed. Moreover, in groups exposed to low doses of ionizing radiation (hospital and factory), a positive correlation was found between the total number of chromosome aberrations and the 6-year absorption dose or working period, suggesting an effect of cumulative dosage. (author)

Paracytosis of Haemophilus influenzae through cell layers of NCI-H292 lung epithelial cells

NARCIS (Netherlands)

van Schilfgaarde, M.; van Alphen, L.; Eijk, P.; Everts, V.; Dankert, J.

1995-01-01

Haemophilus influenzae penetrates the respiratory epithelium during carriage and invasive disease, including respiratory tract infections. We developed an in vitro model system consisting of lung epithelial NCI-H292 cells on permeable supports to study the passage of H. influenzae through lung

NCI Requests Targets for Monoclonal Antibody Production and Characterization | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

In an effort to provide well-characterized monoclonal antibodies to the scientific community, NCI's Antibody Characterization Program requests cancer-related protein targets for affinity production and distribution. Submissions will be accepted through July 9, 2012.

Vibronic coupling in ionized organic molecules. Structural distortions and chemical reactions

International Nuclear Information System (INIS)

Williams, F.

2002-01-01

Complete text of publication follows. Ionized organic molecules (radical cations, RC) are prone to undergo vibronic coupling whenever there is a relatively small energy gap ( 2v point group of the neutral parent molecule by twisting at the olefinic π bond to the lower C 2 symmetry in the RC (Chem. Eur. J. 2002, 8, 1074). These experiments clearly revealed a double minimum in the potential energy surface along the a 2 torsional mode. This is in accord with the coupling of the 2 B 1 and 2 B 2 Born-Oppenheimer states in C 2v symmetry, this mixing of the 2 B 1 π-ionized ground state and the 2 B 2 δ-ionized excited state being facilitated by the low (∼ 1.0 eV) gap between these states, as estimated from photoelectron spectroscopy. Turning to the second class of RC where unimolecular rearrangement reactions are promoted by vibronic interaction, several cases have emerged where the rearrangement would not be expected if it were based only on the ground-state properties of the RC. It was found (Chem. Phy. Lett. 1988, 143, 521) that the ethylene oxide RC undergoes C-C ring opening to the oxallyl species despite the fact that the ground state corresponds to ionization from the nonbonding oxygen π lone-pair orbital. The reaction develops excited-state character as a result of the vibronic mixing so that the activation barrier to ring opening is lowered. We will discuss the unusual rearrangements of the bicyclo[1.1.1.]pentane and [1.1.1]propellane RC from a similar perspective, emphasis being placed on the decisive role of symmetry in predicting the course of these rearrangements. We illustrate how this approach can reconcile conflicting considerations on some of the 'unexpected' reaction pathways followed by highly strained organic RC

Microsoft Office 365 Deployment Continues through June at NCI at Frederick | Poster

Science.gov (United States)

The latest Microsoft suite, Office 365 (O365), is being deployed to all NCI at Frederick computers during the months of May and June to comply with federal mandates. The suite includes the latest versions of Word, Excel, Outlook, PowerPoint, and Skype for Business, along with cloud-based capabilities. These cloud-based capabilities will help meet the federal mandates that

Direct Analysis of Large Living Organism by Megavolt Electrostatic Ionization Mass Spectrometry

Science.gov (United States)

Ng, Kwan-Ming; Tang, Ho-Wai; Man, Sin-Heng; Mak, Pui-Yuk; Choi, Yi-Ching; Wong, Melody Yee-Man

2014-09-01

A new ambient ionization method allowing the direct chemical analysis of living human body by mass spectrometry (MS) was developed. This MS method, namely Megavolt Electrostatic Ionization Mass Spectrometry, is based on electrostatic charging of a living individual to megavolt (MV) potential, illicit drugs, and explosives on skin/glove, flammable solvent on cloth/tissue paper, and volatile food substances in breath were readily ionized and detected by a mass spectrometer.

Chemical profile of pineapple cv. Vitória in different maturation stages using electrospray ionization mass spectrometry.

Science.gov (United States)

Ogawa, Elizângela M; Costa, Helber B; Ventura, José A; Caetano, Luiz Cs; Pinto, Fernanda E; Oliveira, Bruno G; Barroso, Maria Eduarda S; Scherer, Rodrigo; Endringer, Denise C; Romão, Wanderson

2018-02-01

Pineapple is the fruit of Ananas comosus var. comosus plant, being cultivated in tropical areas and has high energy content and nutritional value. Herein, 30 samples of pineapple cv. Vitória were analyzed as a function of the maturation stage (0-5) and their physico-chemical parameters monitored. In addition, negative-ion mode electrospray ionization mass spectrometry [ESI(-)FT-ICR MS] was used to identify and semi-quantify primary and secondary metabolites present in the crude and phenolic extracts of pineapple, respectively. Physico-chemical tests show an increase in the total soluble solids (TSS) values and in the TSS/total titratable acidity ratio as a function of the maturity stage, where a maximum value was observed in stage 3 (¾ of the fruit is yellow, which corresponds to the color of the fruit peel). ESI(-)FT-ICR MS analysis for crude extracts showed the presence mainly of sugars as primary metabolites present in deprotonated molecule form ([M - H] - and [2 M - H] - ions) whereas, for phenolic fractions, 11 compounds were detected, being the most abundant in the third stage of maturation. This behavior was confirmed by quantitative analysis of total polyphenols. ESI-FT-ICR MS was efficient in identifying primary (carbohydrates and organic acids) and secondary metabolites (13 phenolic compounds) presents in the crude and phenolic extract of the samples, respectively. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Physical, chemical, microbiological and sensorial behaviour evolution of non cooked pressed cheese paste while in refrigerated storage, made with red chilli powder, treated by heat or ionization

International Nuclear Information System (INIS)

Iben El Hadj Mohamed, A.

1998-01-01

The evolution of different physical, chemical, microbiological and sensorial characteristics of a Tunisian manufactured cheese made of non cooked pressed cheese paste with red chilli powder treated by heat, was measured while in refrigerated storage and compared to the one treated by ionization (author)

Puerto Rico NCI Community Oncology Research Program Minority/Underserved | Division of Cancer Prevention

Science.gov (United States)

The Puerto Rico NCI Community Oncology Research Program (PRNCORP) will be the principal organization in the island that promotes cancer prevention, control and screening/post-treatment surveillance clinical trials. It will conduct cancer care delivery research and will provide access to treatment and imaging clinical trials conducted under the reorganization of the National

Ionizing radiation for insect control in grain and grain products

International Nuclear Information System (INIS)

Tilton, E.W.; Brower, J.H.

1987-01-01

A technical review summarizes and discusses information on various aspects of the use of ionizing radiation for the control of insect infestation in grains and grain products. Topics include: the effects of ionizing radiation on insects infesting stored-grain products; the 2 main types of irradiators (electron accelerators; radioisotopes (e.g.: Co-60; Cs-137); dosimetry systems and methodology; variations in radiation resistance by stored-product pests; the proper selection of radiation dose; the effects of combining various treatments (temperature, infrared/microwave radiation, hypoxia, chemicals) with ionizing radiation; sublethal radiation for controlling bulk grain insects; the feeding capacity of irradiated insects; the susceptibility of insecticide-resistant insects to ionizing radiation; and the possible resistance of insects to ionizing radiation. Practical aspects of removing insects from irradiated grain also are discussed

Analysis of acylcarnitines as their N-demethylated ester derivatives by gas chromatography-chemical ionization mass spectrometry.

Science.gov (United States)

Huang, Z H; Gage, D A; Bieber, L L; Sweeley, C C

1991-11-15

A novel approach to the analysis of acylcarnitines has been developed. It involves a direct esterification using propyl chloroformate in aqueous propanol followed by ion-pair extraction with potassium iodide into chloroform and subsequent on-column N-demethylation of the resulting acylcarnitine propyl ester iodides. The products, acyl N-demethylcarnitine propyl esters, are volatile and are easily analyzed by gas chromatography-chemical ionization mass spectrometry. For medium-chain-length (C4-C12) acylcarnitine standards, detection limits are demonstrated to be well below 1 ng starting material using selected ion monitoring. Well-separated gas chromatographic peaks and structure-specific mass spectra are obtained with samples of synthetic and biological origin. Seven acylcarnitines have been characterized in the urine of a patient suffering from medium-chain acyl-CoA dehydrogenase deficiency.

Radiation ionization is an underestimated industrial technique

International Nuclear Information System (INIS)

Anon.

1999-01-01

Industrial radiation ionization requires electron beams coming from an accelerator or gamma radiation from a radioactive source (Co 60 ). The energy deposed in the irradiated material modifies its chemical bounds or kills micro-organisms. This process is used in medical material sterilization, in disinfestation of stored and packaged food products, in the production of plastic, in the coloring of glass, in the hardening of electronic components and in the modification of the properties of semi-conductors. For 40 years radiation ionization has been investigated, UNO (United Nations Organization) and WHO (World Health Organisation) recommend it for food processing. With a growing rate of 15% per year for the last 15 years, radiation ionization is now widely used. More than 170 gamma irradiation facilities are operating throughout the world. (A.C.)

Protection policies for ionizing and UV radiation

International Nuclear Information System (INIS)

Bosnjakovic, B.F.M.

1987-01-01

Although ultraviolet radiation is generally considered as being part of non-ionizing radiation, the existing similarities with ionizing radiation are too striking to be overseen. A comparison of these two agents is becoming important in view of the increasing awareness of various environmental and health risks and the tendency to develop more uniform risk management policies with respect to the different physical and chemical agents. This paper explores the similarities and differences of UV and ionizing radiation from the point of view of policies either adopted or in development. Policy determinants include, among others, the following factors: biological effects, dosimetric quantities, relative contribution to exposure from different sources, hazard potential of different sources, quantification of detrimental consequences, public perception of the radiation hazards and regulation developments. These factors are discussed

Chemical chaperones reduce ionizing radiation-induced endoplasmic reticulum stress and cell death in IEC-6 cells

Energy Technology Data Exchange (ETDEWEB)

Lee, Eun Sang; Lee, Hae-June; Lee, Yoon-Jin [Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Jeong, Jae-Hoon [Division of Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Kang, Seongman [Division of Life Sciences, Korea University, Seoul 136-701 (Korea, Republic of); Lim, Young-Bin, E-mail: yblim@kirams.re.kr [Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

2014-07-25

Highlights: • UPR activation precedes caspase activation in irradiated IEC-6 cells. • Chemical ER stress inducers radiosensitize IEC-6 cells. • siRNAs that targeted ER stress responses ameliorate IR-induced cell death. • Chemical chaperons prevent cell death in irradiated IEC-6 cells. - Abstract: Radiotherapy, which is one of the most effective approaches to the treatment of various cancers, plays an important role in malignant cell eradication in the pelvic area and abdomen. However, it also generates some degree of intestinal injury. Apoptosis in the intestinal epithelium is the primary pathological factor that initiates radiation-induced intestinal injury, but the mechanism by which ionizing radiation (IR) induces apoptosis in the intestinal epithelium is not clearly understood. Recently, IR has been shown to induce endoplasmic reticulum (ER) stress, thereby activating the unfolded protein response (UPR) signaling pathway in intestinal epithelial cells. However, the consequences of the IR-induced activation of the UPR signaling pathway on radiosensitivity in intestinal epithelial cells remain to be determined. In this study, we investigated the role of ER stress responses in IR-induced intestinal epithelial cell death. We show that chemical ER stress inducers, such as tunicamycin or thapsigargin, enhanced IR-induced caspase 3 activation and DNA fragmentation in intestinal epithelial cells. Knockdown of Xbp1 or Atf6 with small interfering RNA inhibited IR-induced caspase 3 activation. Treatment with chemical chaperones prevented ER stress and subsequent apoptosis in IR-exposed intestinal epithelial cells. Our results suggest a pro-apoptotic role of ER stress in IR-exposed intestinal epithelial cells. Furthermore, inhibiting ER stress may be an effective strategy to prevent IR-induced intestinal injury.

75 FR 46945 - Proposed Collection; Comment Request; the Drug Accountability Record (Form NIH 2564) (NCI)

Science.gov (United States)

2010-08-04

... Request; the Drug Accountability Record (Form NIH 2564) (NCI) SUMMARY: In compliance with the requirement... Management and Budget (OMB) for review and approval. Proposed Collection Title: The Drug Accountability... agent accountability. In order to fulfill these requirements, a standard Investigational Drug...

Organic liquids as ''activ media'' in a holographic ionizing radiation dosimeter

International Nuclear Information System (INIS)

Nicolau-Rebigan, S.

1979-01-01

Some types of organic liquids for using as activ media in a holographic ionizing radiation dosimeter are presented. One outlined the advantages of the holographic dosimeter comparatively with those of common used dosimeters. One presented the advantages of utilization of the organic liquids comparatively with another chemical systems used in a holographic ionizing radiation dosimeter. (author)

Use of ionizing radiation for preservation of food and feed products

International Nuclear Information System (INIS)

Josephson, E.S.; Brynjolfsson, A.; Wierbicki, E.

1975-01-01

Exposing food to ionizing radiation can contribute to closing the worldwide food deficit by reducing food spoilage losses, by making available more food of higher nutritional quality (animal protein food) to more people, and by keeping prices down by reducing losses. Because ionizing radiation kills disease-causing organisms, it can reduce the incidence of food-borne diseases. It also reduces our dependence upon some of the chemical additives, such as nitrites and nitrates, now being questioned by health authorities to control food spoilage and food-borne diseases. The three basic types of ionizing radiation used for processing of food are electrons (10 MeV maximum energy), X-rays (5 MeV maximum energy) produced by electrons in an X-ray target, and gamma rays from 60 Co and 137 Cs. Electrons, X-rays, and gamma rays cause ionization in the food by either the primary electrons or by the secondary electrons resulting from gamma or X-ray interactions in the food with little rise in temperature and little total chemical change. The ionized and activated molecules form unstable secondary products that kill the organisms. Another effect is to slow down post-harvest growth and maturation in some fruits and vegetables

Ionization in matrix-assisted laser desorption/ionization: singly charged molecular ions are the lucky survivors.

Science.gov (United States)

Karas, M; Glückmann, M; Schäfer, J

2000-01-01

A new model for the ionization processes in UV matrix-assisted laser desorption/ionization (MALDI) which accounts for the major phenomena observed is presented and discussed. The model retains elements of earlier approaches, such as photoionization and photochemical reactions, but it redefines these in the light of new working questions, most importantly why only singly charged ions are detected. Based on experimental evidence, the formation of singly and multiply charged clusters by a deficiency/excess of ions and also by photoionization and subsequent photochemical processes is pointed out to be the major ionization processes, which typically occur in parallel. The generation of electrons and their partial loss into the surrounding vacuum and solid, on the one hand, results in a positively charged ion-neutral plume facilitating a high overall ionization yield. On the other hand, these electrons, and also the large excess of protonated matrix ions in the negative ion mode, induce effective ion reneutralization in the plume. These neutralization processes are most effective for the highly charged cluster ions initially formed. Their fragmentation behaviour is evidenced in fast metastable fragmentation characteristics and agrees well with an electron capture dissociation mechanism and the enthalpy transfer upon neutralization forms the rationale for the prominent fragmentation and intense chemical noise accompanying successful MALDI. Within the course of the paper, cross-correlations with other desorption/ionization techniques and with earlier discussions on their mechanisms are drawn. Copyright 2000 John Wiley & Sons, Ltd.

Ionization techniques in capillary electrophoresis-mass spectrometry: principles, design, and application.

Science.gov (United States)

Hommerson, Paul; Khan, Amjad M; de Jong, Gerhardus J; Somsen, Govert W

2011-01-01

A major step forward in the development and application of capillary electrophoresis (CE) was its coupling to ESI-MS, first reported in 1987. More than two decades later, ESI has remained the principal ionization technique in CE-MS, but a number of other ionization techniques have also been implemented. In this review the state-of-the-art in the employment of soft ionization techniques for CE-MS is presented. First the fundamentals and general challenges of hyphenating conventional CE and microchip electrophoresis with MS are outlined. After elaborating on the characteristics and role of ESI, emphasis is put on alternative ionization techniques including sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI) and continuous-flow fast atom bombardment (CF-FAB). The principle of each ionization technique is outlined and the experimental set-ups of the CE-MS couplings are described. The strengths and limitations of each ionization technique with respect to CE-MS are discussed and the applicability of the various systems is illustrated by a number of typical examples. Copyright © 2011 Wiley Periodicals, Inc.

Time, Concentration, and pH-Dependent Transport and Uptake of Anthocyanins in a Human Gastric Epithelial (NCI-N87 Cell Line

Directory of Open Access Journals (Sweden)

Allison A. Atnip

2017-02-01

Full Text Available Anthocyanins are the largest class of water soluble plant pigments and a common part of the human diet. They may have many potential health benefits, including antioxidant, anti-inflammatory, anti-cancer, and cardioprotective activities. However, anthocyanin metabolism is not well understood. Studies suggest that anthocyanins absorption may occur in the stomach, in which the acidic pH favors anthocyanin stability. A gastric epithelial cell line (NCI-N87 has been used to study the behavior of anthocyanins at a pH range of 3.0–7.4. This work examines the effects of time (0–3 h, concentration (50–1500 µM, and pH (3.0, 5.0, 7.4 on the transport and uptake of anthocyanins using NCI-N87 cells. Anthocyanins were transported from the apical to basolateral side of NCI-N87 cells in time and dose dependent manners. Over the treatment time of 3 h the rate of transport increased, especially with higher anthocyanin concentrations. The non-linear rate of transport may suggest an active mechanism for the transport of anthocyanins across the NCI-N87 monolayer. At apical pH 3.0, higher anthocyanin transport was observed compared to pH 5.0 and 7.4. Reduced transport of anthocyanins was found to occur at apical pH 5.0.

78 FR 2678 - Proposed Collection; Comment Request (60-Day FRN): The National Cancer Institute (NCI...

Science.gov (United States)

2013-01-14

... Request (60-Day FRN): The National Cancer Institute (NCI) SmokefreeTXT (Text Message) Program Evaluation..., Behavioral Scientist/ Health Science Administrator, Division of Cancer Control and Population Sciences, 6130... text message smoking cessation intervention designed for young adult smokers ages 18-29. The Smokefree...

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

Energy Technology Data Exchange (ETDEWEB)

Isselhardt, Brett H. [Univ. of California, Berkeley, CA (United States)

2011-09-01

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of ²³⁵U/²³⁸U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

NCI Requests Cancer Targets for Monoclonal Antibody Production and Characterization | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

In an effort to provide well-characterized monoclonal antibodies to the scientific community, NCI's Antibody Characterization Program requests cancer-related protein targets for affinity production and distribution. Submissions will be accepted through July 11, 2014.

Initial events in the cellular effects of ionizing radiations: clustered damage in DNA

International Nuclear Information System (INIS)

Goodhead, D.T.

1994-01-01

Ionizing radiations produce many hundreds of different simple chemical products in DNA and also multitudes of possible clustered combinations. The simple products, including single-strand breaks, tend to correlate poorly with biological effectiveness. Even for initial double-strand breaks, as a broad class, there is apparently little or no increase in yield with increasing ionization density, in contrast with the large rise in relative biological effectiveness for cellular effects. Track structure analysis has revealed that clustered DNA damage of severity greater than simple double-strand breaks is likely to occur at biologically relevant frequencies with all ionizing radiations. Studies are in progress to describe in more detail the chemical nature of these clustered lesions and to consider the implications for cellular repair. (author)

Specificity enhancement by electrospray ionization multistage mass spectrometry--a valuable tool for differentiation and identification of 'V'-type chemical warfare agents.

Science.gov (United States)

Weissberg, Avi; Tzanani, Nitzan; Dagan, Shai

2013-12-01

The use of chemical warfare agents has become an issue of emerging concern. One of the challenges in analytical monitoring of the extremely toxic 'V'-type chemical weapons [O-alkyl S-(2-dialkylamino)ethyl alkylphosphonothiolates] is to distinguish and identify compounds of similar structure. MS analysis of these compounds reveals mostly fragment/product ions representing the amine-containing residue. Hence, isomers or derivatives with the same amine residue exhibit similar mass spectral patterns in both classical EI/MS and electrospray ionization-MS, leading to unavoidable ambiguity in the identification of the phosphonate moiety. A set of five 'V'-type agents, including O-ethyl S-(2-diisopropylamino)ethyl methylphosphonothiolate (VX), O-isobutyl S-(2-diethylamino)ethyl methylphosphonothiolate (RVX) and O-ethyl S-(2-diethylamino)ethyl methylphosphonothiolate (VM) were studied by liquid chromatography/electrospray ionization/MS, utilizing a QTRAP mass detector. MS/MS enhanced product ion scans and multistage MS(3) experiments were carried out. Based on the results, possible fragmentation pathways were proposed, and a method for the differentiation and identification of structural isomers and derivatives of 'V'-type chemical warfare agents was obtained. MS/MS enhanced product ion scans at various collision energies provided information-rich spectra, although many of the product ions obtained were at low abundance. Employing MS(3) experiments enhanced the selectivity for those low abundance product ions and provided spectra indicative of the different phosphonate groups. Study of the fragmentation pathways, revealing some less expected structures, was carried out and allowed the formulation of mechanistic rules and the determination of sets of ions typical of specific groups, for example, methylphosphonothiolates versus ethylphosphonothiolates. The new group-specific ions elucidated in this work are also useful for screening unknown 'V'-type agents and related

Alanine-polymer dosemeter of ionizing radiation

International Nuclear Information System (INIS)

Tomasinski, Z.; Mirkowski, K.; Panta, P.; Stachowicz, W.

1994-01-01

The method of chemical preparation of alanine-copolymer of ethylene and vinyl acetate has been worked out. The material has been in a form of rods. The content of alanine has not exceeded 30%. The ESR signal of alanine radicals has been detected after exposition to ionizing radiation. The dose-response relationship has been presented

78 FR 53763 - Proposed Collection; 60-day Comment Request Cancer Trials Support Unit (CTSU) (NCI)

Science.gov (United States)

2013-08-30

... proposed data collection projects, the National Cancer Institute (NCI), National Institutes of Health (NIH), will publish periodic summaries of proposed projects to be submitted to the Office of Management and... proposed collection of information, including the validity of the methodology and assumptions used; (3...

Detection and measurement of ionizing radiation

International Nuclear Information System (INIS)

Anon.

1990-01-01

All detection or measurement of radiation rests in the possibility of recognizing the interactions of radiation with matter. When radiation passes through any kind of material medium, all or a portion of its energy is transferred to this medium. This transferred energy produces an effect in the medium. In principle, the detection of radiation is based on the appearance and the observation of this effect. In theory, all of the effects produced by radiation may be used in detecting it: in practice, the effects most commonly employed are: (1) ionization of gases (gas detectors), or of some chemical substance which is transformed by radiation (photographic or chemical dosimeters); (2) excitations in scintillators or semiconductors (scintillation counters, semiconductor counters); (3) creation of structural defects through the passage of radiation (transparent thermoluminescent and radioluminescent detectors); and (4) raising of the temperature (calorimeters). This study evaluates in detail, instruments based on the ionization of gases and the production of luminescence. In addition, the authors summarize instruments which depend on other forms of interaction, used in radiation medicine and hygiene (radiology, nuclear medicine)

Quantitative measurement of the chemical composition of geological standards with a miniature laser ablation/ionization mass spectrometer designed for in situ application in space research

International Nuclear Information System (INIS)

Neuland, M B; Riedo, A; Tulej, M; Wurz, P; Grimaudo, V; Moreno-García, P; Mezger, K

2016-01-01

A key interest of planetary space missions is the quantitative determination of the chemical composition of the planetary surface material. The chemical composition of surface material (minerals, rocks, soils) yields fundamental information that can be used to answer key scientific questions about the formation and evolution of the planetary body in particular and the Solar System in general. We present a miniature time-of-flight type laser ablation/ionization mass spectrometer (LMS) and demonstrate its capability in measuring the elemental and mineralogical composition of planetary surface samples quantitatively by using a femtosecond laser for ablation/ionization. The small size and weight of the LMS make it a remarkable tool for in situ chemical composition measurements in space research, convenient for operation on a lander or rover exploring a planetary surface. In the laboratory, we measured the chemical composition of four geological standard reference samples USGS AGV-2 Andesite, USGS SCo-l Cody Shale, NIST 97b Flint Clay and USGS QLO-1 Quartz Latite with LMS. These standard samples are used to determine the sensitivity factors of the instrument. One important result is that all sensitivity factors are close to 1. Additionally, it is observed that the sensitivity factor of an element depends on its electron configuration, hence on the electron work function and the elemental group in agreement with existing theory. Furthermore, the conformity of the sensitivity factors is supported by mineralogical analyses of the USGS SCo-l and the NIST 97b samples. With the four different reference samples, the consistency of the calibration factors can be demonstrated, which constitutes the fundamental basis for a standard-less measurement-technique for in situ quantitative chemical composition measurements on planetary surface. (paper)

Dissociation mechanism of HNIW ions investigated by chemical ionization and electron impact mass spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yang, Rongjie; Xiao, Hemiao [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2006-04-15

Chemical Ionization (CI) with Collision-Induced Dissociation (CID) spectroscopy and Electron Impacting (EI) with metastable Mass analyzed Ion Kinetic Energy (MIKE) spectroscopy have been applied to study ionic dissociations of Hexanitrohexaazaisowurtzitane (HNIW). Similarities and differences between EI/MIKE and CI/CID mass spectra of HNIW were analyzed. In EI mass spectra, the ions [HNIW-n NO{sub 2}]{sup +} (n=2-5), such as the ion at m/z 347, were less frequent (1-2% relative abundance), but in CI mass spectra, these ions were very abundant. For some ions of large molar mass from HNIW, their dissociations pathways from parent ions to daughter ions were built according to CID and MIKE spectra. Molecular ions of HNIW with a protonated nitro group at five-member ring seem more stable than at six-member ring. The HNIW ions losing five of six nitro groups are very stable based on CID spectra, which agrees with some research results for thermal decomposition of HNIW in literature. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Radiobiology: Biologic effects of ionizing radiations

International Nuclear Information System (INIS)

Held, K.D.

1987-01-01

The biologic effects after exposure to ionizing radiation, such as cell death or tissue injury, result from a chain of complex physical, chemical, metabolic, and histologic events. The time scale of these radiation actions spans many orders of magnitude. The physical absorption of ionizing radiation occurs in about 10 -18 s, while late carcinogenic and genetic effects are expressed years or even generations later. Collectively, these effects form the science of radiobiology. Many of the concepts discussed in this chapter have been developed through the study of effects generated in tissues by external radiation sources, but they apply generally and often specifically to internally distributed radiopharmaceuticals which form the central topic of this book

Comparison of the rationale used in setting occupational exposure standards for ionizing radiation and hazardous chemical substances

International Nuclear Information System (INIS)

Halton, D.M.

1986-12-01

Ten chemicals which create significant occupational hazard are reviewed. They are toluene diisocyanate, hydrogen fluoride, n-hexane, carbon disulphide, cadmium, inorganic mercury, cobalt, nitroglycerol, silica and vinyl chloride. Each is discussed under the headings of physiological intake and elimination in humans, characteristics of acute and chronic toxicity, sites of occupational exposure and rationale for limits of such exposure. Since radioactive substances yield ionizing radiation as the common hazard the treatment of the current permissible levels of exposure is somewhat simpler. Having set out industrial standards for exposure to hazardous substances and radionuclides, a detailed comparison is made. Exposure limits to ioninzing radiation are sufficiently low to remove the appearance of directly related injury. It is expected however that low level exposure may have a stochastic effect, that is, there is the possibility of a slightly increased incidence of neoplasms in a large exposed population, but numbers will be too small to be able to attribute any particular case to the exposure. TLVs on the other hand, depending on the particular chemical, may be high enough in the workplace to permit some directly related signs or symptoms in the exposed individual. 244 refs

Highlights of recent developments and trends in cancer nanotechnology research--view from NCI Alliance for Nanotechnology in Cancer.

Science.gov (United States)

Hull, L C; Farrell, D; Grodzinski, P

2014-01-01

Although the incidence of cancer and cancer related deaths in the United States has decreased over the past two decades due to improvements in early detection and treatment, cancer still is responsible for a quarter of the deaths in this country. There is much room for improvement on the standard treatments currently available and the National Cancer Institute (NCI) has recognized the potential for nanotechnology and nanomaterials in this area. The NCI Alliance for Nanotechnology in Cancer was formed in 2004 to support multidisciplinary researchers in the application of nanotechnology to cancer diagnosis and treatment. The researchers in the Alliance have been productive in generating innovative solutions to some of the central issues of cancer treatment including how to detect tumors earlier, how to target cancer cells specifically, and how to improve the therapeutic index of existing chemotherapies and radiotherapy treatments. Highly creative ideas are being pursued where novelty in nanomaterial development enables new modalities of detection or therapy. This review highlights some of the innovative materials approaches being pursued by researchers funded by the NCI Alliance. Their discoveries to improve the functionality of nanoparticles for medical applications includes the generation of new platforms, improvements in the manufacturing of nanoparticles and determining the underlying reasons for the movement of nanoparticles in the blood. © 2013.

NCI Think Tank Concerning the Identifiability of Biospecimens and “-Omic” Data

OpenAIRE

Weil, Carol J.; Mechanic, Leah E.; Green, Tiffany; Kinsinger, Christopher; Lockhart, Nicole C.; Nelson, Stefanie A.; Rodriguez, Laura L.; Buccini, Laura D.

2013-01-01

On June 11 and 12, 2012, the National Cancer Institute (NCI) hosted a think tank concerning the identifiability of biospecimens and “omic” Data in order to explore challenges surrounding this complex and multifaceted topic. The think tank brought together forty-six leaders from several fields, including cancer genomics, bioinformatics, human subject protection, patient advocacy, and commercial genetics. The first day involved presentations regarding the state of the science of re-identificati...

75 FR 61763 - Submission of OMB Review; Comment Request; Drug Accountability Record (Form NIH 2564) (NCI)

Science.gov (United States)

2010-10-06

...; Comment Request; Drug Accountability Record (Form NIH 2564) (NCI) SUMMARY: In compliance with the..., 2011, unless it displays a valid OMB control number. Proposed Collection: Title: Drug Accountability... accountability. In order to fulfill these requirements, a standard Investigational Drug Accountability Report...

Photoactivatable Lipid-based Nanoparticles as a Vehicle for Dual Agent Delivery | NCI Technology Transfer Center | TTC

Science.gov (United States)

Researchers at the National Cancer Institute (NCI) RNA Biology Laboratory have developed nanoparticles that can deliver an agent (i.e., therapeutic or imaging) and release the agent upon targeted photoactivation allowing for controlled temporal and localized release of the agent.

Test de visualitat: les preferències del bon disseny

Directory of Open Access Journals (Sweden)

Quim Merino

2014-07-01

Full Text Available Aquest article pretén donar notícia de la investigació dirigida pel Grup de Recerca en Publicitat i Relacions Públiques (en endavant, GRP de la Universitat Autònoma de Barcelona duta a terme pels autors d'aquesta ressenya. El treball s'emmarca en una activitat de l'assignatura de Disseny en Publicitat i Relacions Públiques del Grau en Publicitat i Relacions Públiques de la UAB. L'objectiu del treball és constatar les preferències del consumidor davant diferents estímuls formals del disseny gràfic en publicitat

Charge correlation effects on ionization of weak polyelectrolytes

International Nuclear Information System (INIS)

Panagiotopoulos, A Z

2009-01-01

Ionization curves of weak polyelectrolytes were obtained as a function of the charge coupling strength from Monte Carlo simulations. In contrast to many earlier studies, the present work treats counterions explicitly, thus allowing the investigation of charge correlation effects at strong couplings. For conditions representing typical weak polyelectrolytes in water near room temperature, ionization is suppressed because of interactions between nearby dissociated groups, as also seen in prior work. A novel finding here is that, for stronger couplings, relevant for non-aqueous environments in the absence of added salt, the opposite behavior is observed-ionization is enhanced relative to the behavior of the isolated groups due to ion-counterion correlation effects. The fraction of dissociated groups as a function of position along the chain also behaves non-monotonically. Dissociation is highest near the ends of the chains for aqueous polyelectrolytes and highest at the chain middle segments for non-aqueous environments. At intermediate coupling strengths, dissociable groups appear to behave in a nearly ideal fashion, even though chain dimensions still show strong expansion effects due to ionization. These findings provide physical insights on the impact of competition between acid/base chemical equilibrium and electrostatic attractions in ionizable systems.

Negative chemical ionization GC/MS determination of nitrite and nitrate in seawater using exact matching double spike isotope dilution and derivatization with triethyloxonium tetrafluoroborate.

Science.gov (United States)

Pagliano, Enea; Meija, Juris; Sturgeon, Ralph E; Mester, Zoltan; D'Ulivo, Alessandro

2012-03-06

The alkylation of nitrite and nitrate by triethyloxonium tetrafluoroborate allows determination of their ethyl esters by headspace gas chromatography/mass spectrometry (GC/MS). In the present study, significant improvement in analytical performance is achieved using negative chemical ionization providing detection limits of 150 ng/L for NO(2)(-) and 600 ng/L for NO(3)(-), an order of magnitude better than those achieved using electron impact ionization. The derivatization procedure was optimized and alkaline conditions adopted to minimize conversion of nitrite to nitrate (determined to be 0.07% at 100 mg/L NO(2)(-)) and to avoid the exchange of oxygen between the analytes and the solvent (water). Quantitation entails use of isotopically enriched standards (N(18)O(2)(-) and (15)NO(3)(-)), which also permits monitoring of potential conversion from nitrite to nitrate during the analysis (double spike isotope dilution).

Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry

Science.gov (United States)

Colizza, Kevin; Mahoney, Keira E.; Yevdokimov, Alexander V.; Smith, James L.; Oxley, Jimmie C.

2016-11-01

Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression.

Reducing Friction: An Update on the NCIP Open Development Initiative - NCI BioMedical Informatics Blog

Science.gov (United States)

NCIP has migrated 132 repositories from the NCI subversion repository to our public NCIP GitHub channel with the goal of facilitating third party contributions to the existing code base. Within the GitHub environment, we are advocating use of the GitHub “fork and pull” model.

77 FR 4334 - Proposed Collection; Comment Request; Solar Cell: A Mobile UV Manager for Smart Phones (NCI)

Science.gov (United States)

2012-01-27

... DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health Proposed Collection; Comment Request; Solar Cell: A Mobile UV Manager for Smart Phones (NCI) SUMMARY: In compliance with the... Manager for Smart Phones [[Page 4335

HO2 measurements at atmospheric concentrations using a chemical ionization mass spectrometry

Science.gov (United States)

Albrecht, S.; Novelli, A.; Hofzumahaus, A.; Kang, S.; Baker, Y.; Mentel, T. F.; Fuchs, H.

2017-12-01

Correct and precise measurements of atmospheric radical species are necessary for a better understanding of the oxidative capacity of the atmosphere. Due to the reactivity of radicals, and their consequent low concentrations, direct measurements of these species are particularly challenging and have been proven in the past to be affected by interfering species. Here we present a chemical ionization source coupled to an APi-HR-TOF-MS (Aerodyne Research Inc.), which has a limit of detection for HO2 radicals well below its atmospheric concentrations ( 1 x 108 molecules cm-3). The instrument was calibrated with a well-established and characterized HO2 calibration source in use for the laser induced fluorescence instrument in the Forschungszentrum Jülich. Within the source, a well characterized amount of HO2 radicals is produced after photolysis of water by a mercury lamp. In addition, several experiments were performed in the atmosphere simulation chamber SAPHIR at the Forschungszentrum Jülich to test for potential interferences. Measurements of HO2 radicals were concurrently detected by a laser induced fluorescence instrument allowing for the comparison of measurements within the two different and independent techniques for various atmospheric conditions regarding concentrations of O3, NOx and VOCs. Results from the intercomparison together with the calibration procedure of the instrument and laboratory characterization will be presented.

Trace determination of 13 haloacetamides in drinking water using liquid chromatography triple quadrupole mass spectrometry with atmospheric pressure chemical ionization.

Science.gov (United States)

Chu, Wenhai; Gao, Naiyun; Yin, Daqiang; Krasner, Stuart W; Templeton, Michael R

2012-04-27

The haloacetamides (HAcAms) are disinfection by-products (DBPs) in drinking water which are currently receiving increased scientific attention due to their elevated toxicity relative to regulated disinfection by-products. A simultaneous determination method of 13 HAcAms, combining solid-phase extraction (SPE) enrichment, liquid chromatographic (LC) separation, and triple quadrupole mass spectrometry (tqMS) detection with atmospheric pressure chemical ionization (APCI) using selective reaction monitoring in positive mode, was developed to measure HAcAms, including chlorinated, brominated, and iodinated analogs. Ammonium chloride and Oasis HLB were selected as the dechlorinating reagent and polymeric SPE sorbent of HAcAm samples. The used tqMS apparatus showed higher sensitivity for the studied HAcAms in the APCI mode than electrospray ionization. 13 HAcAms were separated by LC in 9.0 min, and the detection limits ranged from 7.6 to 19.7 ng/L. The SPE-LC/tqMS method was successfully applied to quantify 13 HAcAms in drinking water samples for the first time, and first indentified tribromoacetamide and chloroiodoacetamide as DBPs in drinking water. Copyright © 2012 Elsevier B.V. All rights reserved.

Chemical analysis of raw and processed Fructus arctii by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry

Science.gov (United States)

Qin, Kunming; Liu, Qidi; Cai, Hao; Cao, Gang; Lu, Tulin; Shen, Baojia; Shu, Yachun; Cai, Baochang

2014-01-01

Background: In traditional Chinese medicine (TCM), raw and processed herbs are used to treat the different diseases. Fructus Arctii, the dried fruits of Arctium lappa l. (Compositae), is widely used in the TCM. Stir-frying is the most common processing method, which might modify the chemical compositions in Fructus Arctii. Materials and Methods: To test this hypothesis, we focused on analysis and identification of the main chemical constituents in raw and processed Fructus Arctii (PFA) by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry. Results: The results indicated that there was less arctiin in stir-fried materials than in raw materials. however, there were higher levels of arctigenin in stir-fried materials than in raw materials. Conclusion: We suggest that arctiin reduced significantly following the thermal conversion of arctiin to arctigenin. In conclusion, this finding may shed some light on understanding the differences in the therapeutic values of raw versus PFA in TCM. PMID:25422559

Improving global data infrastructures for more effective and scalable analysis of Earth and environmental data: the Australian NCI NERDIP Approach

Science.gov (United States)

Evans, Ben; Wyborn, Lesley; Druken, Kelsey; Richards, Clare; Trenham, Claire; Wang, Jingbo; Rozas Larraondo, Pablo; Steer, Adam; Smillie, Jon

2017-04-01

The National Computational Infrastructure (NCI) facility hosts one of Australia's largest repositories (10+ PBytes) of research data collections spanning datasets from climate, coasts, oceans, and geophysics through to astronomy, bioinformatics, and the social sciences domains. The data are obtained from national and international sources, spanning a wide range of gridded and ungridded (i.e., line surveys, point clouds) data, and raster imagery, as well as diverse coordinate reference projections and resolutions. Rather than managing these data assets as a digital library, whereby users can discover and download files to personal servers (similar to borrowing 'books' from a 'library'), NCI has built an extensive and well-integrated research data platform, the National Environmental Research Data Interoperability Platform (NERDIP, http://nci.org.au/data-collections/nerdip/). The NERDIP architecture enables programmatic access to data via standards-compliant services for high performance data analysis, and provides a flexible cloud-based environment to facilitate the next generation of transdisciplinary scientific research across all data domains. To improve use of modern scalable data infrastructures that are focused on efficient data analysis, the data organisation needs to be carefully managed including performance evaluations of projections and coordinate systems, data encoding standards and formats. A complication is that we have often found multiple domain vocabularies and ontologies are associated with equivalent datasets. It is not practical for individual dataset managers to determine which standards are best to apply to their dataset as this could impact accessibility and interoperability. Instead, they need to work with data custodians across interrelated communities and, in partnership with the data repository, the international scientific community to determine the most useful approach. For the data repository, this approach is essential to enable

An Atmospheric Pressure Chemical Ionization MS/MS Assay Using Online Extraction for the Analysis of 11 Cannabinoids and Metabolites in Human Plasma and Urine.

Science.gov (United States)

Klawitter, Jelena; Sempio, Cristina; Mörlein, Sophie; De Bloois, Erik; Klepacki, Jacek; Henthorn, Thomas; Leehey, Maureen A; Hoffenberg, Edward J; Knupp, Kelly; Wang, George S; Hopfer, Christian; Kinney, Greg; Bowler, Russell; Foreman, Nicholas; Galinkin, Jeffrey; Christians, Uwe; Klawitter, Jost

2017-10-01

Although, especially in the United States, there has been a recent surge of legalized cannabis for either recreational or medicinal purposes, surprisingly little is known about clinical dose-response relationships, pharmacodynamic and toxicodynamic effects of cannabinoids such as Δ9-tetrahydrocannabinol (THC). Even less is known about other active cannabinoids. To address this knowledge gap, an online extraction, high-performance liquid chromatography coupled with tandem mass spectrometry method for simultaneous quantification of 11 cannabinoids and metabolites including THC, 11-hydroxy-Δ9-tetrahydrocannabinol, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide (THC-C-gluc), cannabinol, cannabidiol, cannabigerol, cannabidivarin, Δ9-tetrahydrocannabivarin (THCV), and 11-nor-9-carboxy-Δ9-tetrahydrocannabivarin (THCV-COOH) was developed and validated in human urine and plasma. In contrast to atmospheric pressure chemical ionization, electrospray ionization was associated with extensive ion suppression in plasma and urine samples. Thus, the atmospheric pressure chemical ionization assay was validated showing a lower limit of quantification ranging from 0.39 to 3.91 ng/mL depending on study compound and matrix. The upper limit of quantification was 400 ng/mL except for THC-C-gluc with an upper limit of quantification of 2000 ng/mL. The linearity was r > 0.99 for all analyzed calibration curves. Acceptance criteria for intrabatch and interbatch accuracy (85%-115%) and imprecision (<15%) were met for all compounds. In plasma, the only exceptions were THCV (75.3%-121.2% interbatch accuracy) and cannabidivarin (interbatch imprecision, 15.7%-17.2%). In urine, THCV did not meet predefined acceptance criteria for intrabatch accuracy. This assay allows for monitoring not only THC and its major metabolites but also major cannabinoids that are of interest for marijuana research and clinical practice.

Ionization of anisothermal plasmas

International Nuclear Information System (INIS)

Dennery, F.M.

1994-01-01

During this last mid-century, only the temperature of electrons has been involved in the Saha's mass action law, whatever be the other ionic and neutral ones in any isothermal or anisothermal plasma. In order to set aside this underlying paradox in the case of argon ionization, it is necessary to improve this equation of partial equilibrium after having defined: - the basic Gibbs-Duhem's relations for such a polythermal mixture, - the inhomogeneous equilibrium issued from chemical reactions according to Le Chatelier's principle. (author). 3 refs

The national cancer institute (NCI) and cancer biology in a 'post genome world'

International Nuclear Information System (INIS)

Klausner, Richard D.

1996-01-01

The National Cancer Institute (NCI) exists to reduce the burden of all cancers through research and discovery. Extensive restructuring of the NCI over the past year has been aimed at assuring that the institution functions in all ways to promote opportunities for discovery in the laboratory, in the clinic, and in the community. To do this well requires the difficult and almost paradoxical problem of planning for scientific discovery which, in turn is based on the freedom to pursue the unanticipated. The intellectual and structural landscape of science is changing and it places new challenges, new demands and new opportunities for facilitating discovery. The nature of cancer as a disease of genomic instability and of accumulated genetic change, coupled with a possibility of the development of new technologies for reading, utilizing, interpreting and manipulating the genome of single cells, provides unprecedented opportunities for a new type of high through-put biology that will change the nature of discovery, cancer detection, diagnosis, prognosis, therapeutic decision-making and therapeutic discovery. To capture these new opportunities will require attention to be paid to integrate the development of technology and new scientific discoveries with the ability to apply advances rapidly and efficiently through clinical trials

Chemical effects produced by the ionizing radiation in the mercury beating heart reaction

International Nuclear Information System (INIS)

Castillo-Rojas, S.; Burillo, G.; Gonzalez-Chavez, J.L.; Vicente, L.

2002-01-01

Complete text of publication follows. In a recent paper we have shown the existence of complex modes of oscillation in the study of the extinction dynamics of the mercury beating heart reaction. It was proposed that one of the species responsible for the oscillatory movements of this reaction is the mercury(I), in anyone in their forms, either free or molecular. the formation of Hg 2 2+ from γ irradiation of 60 Co to the system Hg 0 /H 2 SO 4 (6M) allowed to elucidate the probable mechanism of reaction. The objective of this work is to study how the ionizing radiation affects the dynamics of extinction of this reaction, which is related with the existence of certain chemical species. The study was carried out in 2 ways: a) Method I: H 2 SO 4 (6M) was first irradiated and to the irradiated solution the Hg 0 was added and b) Method II: the system Hg 0 /H 2 SO 4 (6M) was irradiated. The different irradiated systems were put into reaction with Fe 0 to investigate if there were differences between the two irradiated systems and how the complex modes of oscillation of the reaction were affected. The quantity of Hg 2 2+ produced by method I is bigger than in method II. This is explained because the majority species produced by radiolysis of H 2 SO 4 are sulfate radical and H 2 O 2 that act as oxidizer agents and their potential values allow to suppose that these substances react with Hg 0 to produce Hg 2 2+ . On the other hand, by method II mercury clusters (Hg 4 3+ ) are formed as was reported by Sukhov and Ershov in pulse radiolysis of aqueous Hg 2 2+ solutions. We assume that the formation of these mercury clusters has to be observed with the decrease of the Hg 2 2+ concentration when one makes the radiolysis by method II. In general, the preliminary studies allow establishing that the ionizing radiation does not affect the extinction dynamics but it increases the half-life of this reaction

[Determination of naphthenic acids in distillates of crude oil by gas chromatography/chemical ionization-mass spectrometry].

Science.gov (United States)

Lü, Zhenbo; Tian, Songbai; Zhai, Yuchun; Sun, Yanwei; Zhuang, Lihong

2004-05-01

The petroleum carboxylic acids in 200-420 degrees C distillate of crude oil were separated by the extraction with column chromatography on an anion exchange resin. The effect of the composition and structure of naphthenic acids on separation were studied by the infra-red (IR) spectroscopic techniques. Naphthenic acids and iso-butane reagent gas were introduced into the ion source for chemical ionization, in which the ions represented by [M + C4H9]+ were used to calculate the relative molecular mass for each acid. Based on the mass spectra of pure fatty and naphthenic acids, in combination with the z-series formula CnH(2n + z)O2, the naphthenic acids can be classified into fatty, mono-, bi- ... hexa-cyclic types. The results indicated that the relative molecular mass range of naphthenic acids in this distillates was 170-510, and the carbon number range was C10-C35. The contents of bi-cyclic and tri-cyclic naphthenic acids were higher than others.

NCI Workshop Report: Clinical and Computational Requirements for Correlating Imaging Phenotypes with Genomics Signatures

Directory of Open Access Journals (Sweden)

Rivka Colen

2014-10-01

Full Text Available The National Cancer Institute (NCI Cancer Imaging Program organized two related workshops on June 26–27, 2013, entitled “Correlating Imaging Phenotypes with Genomics Signatures Research” and “Scalable Computational Resources as Required for Imaging-Genomics Decision Support Systems.” The first workshop focused on clinical and scientific requirements, exploring our knowledge of phenotypic characteristics of cancer biological properties to determine whether the field is sufficiently advanced to correlate with imaging phenotypes that underpin genomics and clinical outcomes, and exploring new scientific methods to extract phenotypic features from medical images and relate them to genomics analyses. The second workshop focused on computational methods that explore informatics and computational requirements to extract phenotypic features from medical images and relate them to genomics analyses and improve the accessibility and speed of dissemination of existing NIH resources. These workshops linked clinical and scientific requirements of currently known phenotypic and genotypic cancer biology characteristics with imaging phenotypes that underpin genomics and clinical outcomes. The group generated a set of recommendations to NCI leadership and the research community that encourage and support development of the emerging radiogenomics research field to address short-and longer-term goals in cancer research.

NCI-FDA Interagency Oncology Task Force Workshop Provides Guidance for Analytical Validation of Protein-based Multiplex Assays | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

An NCI-FDA Interagency Oncology Task Force (IOTF) Molecular Diagnostics Workshop was held on October 30, 2008 in Cambridge, MA, to discuss requirements for analytical validation of protein-based multiplex technologies in the context of its intended use. This workshop developed through NCI's Clinical Proteomic Technologies for Cancer initiative and the FDA focused on technology-specific analytical validation processes to be addressed prior to use in clinical settings. In making this workshop unique, a case study approach was used to discuss issues related to

NCI Statement on the U.S. Surgeon General's "Call to Action to Prevent Skin Cancer"

Science.gov (United States)

As the Federal Government's principal agency for cancer research and training, the National Cancer Institute (NCI) endorses the U.S. Surgeon General’s “Call to Action to Prevent Skin Cancer,” which provides a comprehensive evaluation of the current state of skin cancer prevention efforts in the United States and recommends actions for improvement in the future.

Role of free radicals in radiation chemical aging

Energy Technology Data Exchange (ETDEWEB)

Greenstock, C L

1986-01-01

Ionizing radiation initiates chemical changes in DNA, phospholipid membranes and other critical cell targets, that, if allowed to accumulate unrepaired, may lead to aging and other chronic effects. The chemical effects are free radical mediated, the principal damaging species being radical OH and to a lesser extent O2-anion radical and the molecular product H/sub 2/O/sub 2/. Many compounds can act in combination with ionizing radiation, to amplify the potential oxidative stress. Chemicals, ultra-violet light, lipid peroxides and their breakdown products may increase the extent of acute and chronic radiobiological effects.

Modeling of plasma chemical processes in the artificial ionized layer in the upper atmosphere by the nanosecond corona discharge

Science.gov (United States)

Vikharev, A. L.; Gorbachev, A. M.; Ivanov, O. A.; Kolisko, A. L.; Litvak, A. G.

1993-08-01

The plasma chemical processes in the corona discharge formed in air by a series of high voltage pulses of nanosecond duration are investigated experimentally. The experimental conditions (reduced electric field, duration and repetition frequency of the pulses, gas pressure in the chamber) modeled the regime of creation of the artificial ionized layer (AIL) in the upper atmosphere by a nanosecond microwave discharge. It was found that in a nanosecond microwave discharge predominantly generation of ozone occurs, and that the production of nitrogen dioxide is not large. The energy expenditures for the generation of one O 3 molecule were about 15 eV. On the basis of the experimental results the prognosis of the efficiency of ozone generation in AIL was made.

L’avaluació de competències a l’Educació Superior: el cas d’un màster universitari

Directory of Open Access Journals (Sweden)

Xavier Ma. Triadó i Ivern

2013-01-01

Full Text Available La implantació de les competències és una tasca que ha anat incorporant-se paulatinament pels docents de la universitat espanyola amb l’entrada en vigor del EEES. Tot i això, encara s’està lluny d’aconseguir nivells òptims d’avaluació de les mateixes. Aquest article permet reflexionar sobre algunes bones practiques al respecte i sobre les dificultats i limitacions que apareixen en voler implementar un canvi en les metodologies docents, en el marc d’un màster universitari. Els resultats indiquen el grau en què s’han avaluat i adquirit tant les competències genèriques com especifiques en l’educació superior.

An evaluation of liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization for the rapid and simultaneous measurement of carbamate pesticides and organophorus pesticides

International Nuclear Information System (INIS)

Kim, Byung Joo; So, Hun Young

2000-01-01

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 μg/mL. The peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to tun. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng

An evaluation of liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization for the rapid and simultaneous measurement of carbamate pesticides and organophorus pesticides

Energy Technology Data Exchange (ETDEWEB)

Kim, Byung Joo; So, Hun Young [Korea Research Institute of Standards and Sceince, Taejon (Korea, Republic of)

2000-05-01

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 {mu}g/mL. The peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to tun. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng.

Chemical vapor deposition of aminopropyl silanes in microfluidic channels for highly efficient microchip capillary electrophoresis-electrospray ionization-mass spectrometry.

Science.gov (United States)

Batz, Nicholas G; Mellors, J Scott; Alarie, Jean Pierre; Ramsey, J Michael

2014-04-01

We describe a chemical vapor deposition (CVD) method for the surface modification of glass microfluidic devices designed to perform electrophoretic separations of cationic species. The microfluidic channel surfaces were modified using aminopropyl silane reagents. Coating homogeneity was inferred by precise measurement of the separation efficiency and electroosmotic mobility for multiple microfluidic devices. Devices coated with (3-aminopropyl)di-isopropylethoxysilane (APDIPES) yielded near diffusion-limited separations and exhibited little change in electroosmotic mobility between pH 2.8 and pH 7.5. We further evaluated the temporal stability of both APDIPES and (3-aminopropyl)triethoxysilane (APTES) coatings when stored for a total of 1 week under vacuum at 4 °C or filled with pH 2.8 background electrolyte at room temperature. Measurements of electroosmotic flow (EOF) and separation efficiency during this time confirmed that both coatings were stable under both conditions. Microfluidic devices with a 23 cm long, serpentine electrophoretic separation channel and integrated nanoelectrospray ionization emitter were CVD coated with APDIPES and used for capillary electrophoresis (CE)-electrospray ionization (ESI)-mass spectrometry (MS) of peptides and proteins. Peptide separations were fast and highly efficient, yielding theoretical plate counts over 600,000 and a peak capacity of 64 in less than 90 s. Intact protein separations using these devices yielded Gaussian peak profiles with separation efficiencies between 100,000 and 400,000 theoretical plates.

Laser-enhanced ionization spectroscopy around the ionization limit

International Nuclear Information System (INIS)

Axner, O.; Berglind, T.; Sjoestroem, S.

1986-01-01

Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

Science.gov (United States)

Chen, Hsiao-Wen; Johnson, Sean D.; Zahedy, Fakhri S.; Rauch, Michael; Mulchaey, John S.

2017-06-01

Gas metallicity is a key quantity used to determine the physical conditions of gaseous clouds in a wide range of astronomical environments, including interstellar and intergalactic space. In particular, considerable effort in circumgalactic medium (CGM) studies focuses on metallicity measurements because gas metallicity serves as a critical discriminator for whether the observed heavy ions in the CGM originate in chemically enriched outflows or in more chemically pristine gas accreted from the intergalactic medium. However, because the gas is ionized, a necessary first step in determining CGM metallicity is to constrain the ionization state of the gas which, in addition to gas density, depends on the ultraviolet background radiation field (UVB). While it is generally acknowledged that both the intensity and spectral slope of the UVB are uncertain, the impact of an uncertain spectral slope has not been properly addressed in the literature. This Letter shows that adopting a different spectral slope can result in an order of magnitude difference in the inferred CGM metallicity. Specifically, a harder UVB spectrum leads to a higher estimated gas metallicity for a given set of observed ionic column densities. Therefore, such systematic uncertainties must be folded into the error budget for metallicity estimates of ionized gas. An initial study shows that empirical diagnostics are available for discriminating between hard and soft ionizing spectra. Applying these diagnostics helps reduce the systematic uncertainties in CGM metallicity estimates.

Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

Energy Technology Data Exchange (ETDEWEB)

Chen, Hsiao-Wen; Zahedy, Fakhri S. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637 (United States); Johnson, Sean D. [Department of Astrophysics, Princeton University, Princeton, NJ (United States); Rauch, Michael; Mulchaey, John S., E-mail: hchen@oddjob.uchicago.edu [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2017-06-20

Gas metallicity is a key quantity used to determine the physical conditions of gaseous clouds in a wide range of astronomical environments, including interstellar and intergalactic space. In particular, considerable effort in circumgalactic medium (CGM) studies focuses on metallicity measurements because gas metallicity serves as a critical discriminator for whether the observed heavy ions in the CGM originate in chemically enriched outflows or in more chemically pristine gas accreted from the intergalactic medium. However, because the gas is ionized, a necessary first step in determining CGM metallicity is to constrain the ionization state of the gas which, in addition to gas density, depends on the ultraviolet background radiation field (UVB). While it is generally acknowledged that both the intensity and spectral slope of the UVB are uncertain, the impact of an uncertain spectral slope has not been properly addressed in the literature. This Letter shows that adopting a different spectral slope can result in an order of magnitude difference in the inferred CGM metallicity. Specifically, a harder UVB spectrum leads to a higher estimated gas metallicity for a given set of observed ionic column densities. Therefore, such systematic uncertainties must be folded into the error budget for metallicity estimates of ionized gas. An initial study shows that empirical diagnostics are available for discriminating between hard and soft ionizing spectra. Applying these diagnostics helps reduce the systematic uncertainties in CGM metallicity estimates.

Approximate thermodynamic state relations in partially ionized gas mixtures

International Nuclear Information System (INIS)

Ramshaw, John D.

2004-01-01

Thermodynamic state relations for mixtures of partially ionized nonideal gases are often approximated by artificially partitioning the mixture into compartments or subvolumes occupied by the pure partially ionized constituent gases, and requiring these subvolumes to be in temperature and pressure equilibrium. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral (nonionized) ideal gases. The purpose of this paper is to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation in nonideal plasma mixtures

Derivatization reagents in liquid chromatography/electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Santa, Tomofumi

2011-01-01

Liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is one of the most prominent analytical techniques owing to its inherent selectivity and sensitivity. In LC/ESI-MS/MS, chemical derivatization is often used to enhance the detection sensitivity. Derivatization improves the chromatographic separation, and enhances the mass spectrometric ionization efficiency and MS/MS detectability. In this review, an overview of the derivatization reagents which have been applied to LC/ESI-MS/MS is presented, focusing on the applications to low molecular weight compounds. 2010 John Wiley & Sons, Ltd.

[Ionizing and non-ionizing radiation (comparative risk estimations)].

Science.gov (United States)

Grigor'ev, Iu G

2012-01-01

The population has widely used mobile communication for already more than 15 years. It is important to note that the use of mobile communication has sharply changed the conditions of daily exposure of the population to EME We expose our brain daily for the first time in the entire civilization. The mobile phone is an open and uncontrollable source of electromagnetic radiation. The comparative risk estimation for the population of ionizing and non-ionizing radiation was carried out taking into account the real conditions of influence. Comparison of risks for the population of ionizing and non-ionizing radiation leads us to a conclusion that EMF RF exposure in conditions of wide use of mobile communication is potentially more harmful than ionizing radiation influence.

共价键的离子化%Ionization of Covalent Bond

Institute of Scientific and Technical Information of China (English)

王稼国; 荆西平

2017-01-01

本文用化学键理论分析和推导了共价键离子化的几种方式,包括金属和非金属单质中共价键的诱导离子化、化合物中共价键的降温和自诱导离子化以及含氢化合物和金属化合物的诱导离子化.从能量角度分析了离子化趋势的规律性,并且讨论了共价键的离子化的一些重要应用.%Several ionization patterns of covalent bond,including induced-ionization of covalent bond in metals and nonmetals,induced-ionization of covalent bond in hydrogen compounds and metal compounds,lowering temperature and self-induced ionization of compound,and so on,were dedueed and analyzed by using chemical bond theory.The trend of ionization was also analyzed on energy changing and several important applications of the ionization of covalent bond were discussed.

Metformin synergistically enhances antiproliferative effects of cisplatin and etoposide in NCI-H460 human lung cancer cells

Directory of Open Access Journals (Sweden)

Sarah Fernandes Teixeira

2013-12-01

Full Text Available OBJECTIVE: To test the effectiveness of combining conventional antineoplastic drugs (cisplatin and etoposide with metformin in the treatment of non-small cell lung cancer in the NCI-H460 cell line, in order to develop new therapeutic options with high efficacy and low toxicity.METHODS: We used the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and calculated the combination index for the drugs studied.RESULTS: We found that the use of metformin as monotherapy reduced the metabolic viability of the cell line studied. Combining metformin with cisplatin or etoposide produced a synergistic effect and was more effective than was the use of cisplatin or etoposide as monotherapy.CONCLUSIONS: Metformin, due to its independent effects on liver kinase B1, had antiproliferative effects on the NCI-H460 cell line. When metformin was combined with cisplatin or etoposide, the cell death rate was even higher.

Equation of state of partially-ionized dense plasmas

International Nuclear Information System (INIS)

Rogers, F.J.

1989-01-01

This paper describes methods for calculating the equation of state of partially-ionized dense plasmas. The term dense plasma is used rather than strongly coupled plasma, since it is possible that at plasma conditions such that only a few levels can be observed spectroscopically the plasma coupling parameters are not large. Due mainly to their importance in theoretical astrophysics, the properties of partially ionized plasmas have been of interest for a long while. More recently, this interest has intensified due to the development of methods for producing partially ionized plasmas in the laboratory. This has opened up large programs of experimental investigation and of practical application. In this paper we consider detailed statistical mechanical methods that explicitly treat the distribution over ionic species and their energy level structure. These detailed approaches are generally characterized as being in the ''chemical picture'' when a free energy expression is minimized or in the ''physical picture'' when the starting point is the grand canonical ensemble. 52 refs., 2 tabs

Chemical reaction dynamics using the Advanced Light Source

International Nuclear Information System (INIS)

Yang, X.; Blank, D.A.; Heimann, P.A.; Lee, Y.T.; Suits, A.G.; Lin, J.; Wodtke, A.M.

1995-01-01

The recently commissioned Advanced Light Source (ALS) at Berkeley provides a high brightness, tunable VUV light source for chemical dynamics studies. A dedicated chemical dynamics beamline has been built at the ALS for studies of fundamental chemical processes. High flux (10(sup 16) photon/s with 2% bandwidth) VUV synchrotron radiation from 5 to 30 eV can be obtained from the beamline, whose source is the U8/10 undulator. Three endstations will be in operation for studies ranging from crossed beam reaction dynamics and photodissociation to high resolution photoionization dynamics and spectroscopy. A rotatable source crossed molecular beam apparatus (endstation one) has been established for unimolecular and bimolecular reactive scattering studies. Photodissociation of methylamine and ozone were carried out using VUV synchrotron radiation as the ionization detection technique at this endstation. Results show the advantages of the new endstation using VUV ionization as the detection scheme over similar machines using electron bombardment as the ionization source

Chemical reaction dynamics using the Advanced Light Source

International Nuclear Information System (INIS)

Yang, X.; Blank, D.A.; Heimann, P.A.; Lee, Y.T.; Suits, A.G.; Lin, J.; Wodtke, A.M.

1995-09-01

The recently commissioned Advanced Light Source (ALS) at Berkeley provides a high brightness, tunable VUV light source for chemical dynamics studies. A dedicated chemical dynamics beamline has been built at the ALS for studies of fundamental chemical processes. High flux (10 16 photon/s with 2% bandwidth) VUV synchrotron radiation from 5 to 30 eV can be obtained from the beamline, whose source is the U8/10 undulator. Three endstations will be in operation for studies ranging from crossed beam reaction dynamics and photodissociation to high resolution photoionization dynamics and spectroscopy. A rotatable source crossed molecular beam apparatus (endstation one) has been established for unimolecular and bimolecular reactive scattering studies. Photodissociation of methylamine and ozone were carried out using VUV synchrotron radiation as the ionization detection technique at this endstation. Results show the advantages of the new endstation using VUV ionization as the detection scheme over similar machines using electron bombardment as the ionization source

Ionization photophysics and spectroscopy of cyanoacetylene

International Nuclear Information System (INIS)

Leach, Sydney; Champion, Norbert; Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François; Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin

2014-01-01

Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC 3 N involves new aspects and new assignments of the vibrational components to excitation of the A 2 Σ + and B 2 Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B 2 Π state of HC 3 N + . A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C 2 Σ + state of HC 3 N + at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised

All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

Science.gov (United States)

Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

2016-02-01

We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

Enhanced Missing Proteins Detection in NCI60 Cell Lines Using an Integrative Search Engine Approach.

Science.gov (United States)

Guruceaga, Elizabeth; Garin-Muga, Alba; Prieto, Gorka; Bejarano, Bartolomé; Marcilla, Miguel; Marín-Vicente, Consuelo; Perez-Riverol, Yasset; Casal, J Ignacio; Vizcaíno, Juan Antonio; Corrales, Fernando J; Segura, Victor

2017-12-01

The Human Proteome Project (HPP) aims deciphering the complete map of the human proteome. In the past few years, significant efforts of the HPP teams have been dedicated to the experimental detection of the missing proteins, which lack reliable mass spectrometry evidence of their existence. In this endeavor, an in depth analysis of shotgun experiments might represent a valuable resource to select a biological matrix in design validation experiments. In this work, we used all the proteomic experiments from the NCI60 cell lines and applied an integrative approach based on the results obtained from Comet, Mascot, OMSSA, and X!Tandem. This workflow benefits from the complementarity of these search engines to increase the proteome coverage. Five missing proteins C-HPP guidelines compliant were identified, although further validation is needed. Moreover, 165 missing proteins were detected with only one unique peptide, and their functional analysis supported their participation in cellular pathways as was also proposed in other studies. Finally, we performed a combined analysis of the gene expression levels and the proteomic identifications from the common cell lines between the NCI60 and the CCLE project to suggest alternatives for further validation of missing protein observations.

Analysis of vitamin K-1 in fruits and vegetables using accelerated solvent extraction and liquid chromatography tandem mass spectrometry with atmospheric pressure chemical ionization

DEFF Research Database (Denmark)

Jäpelt, Rie Bak; Jakobsen, Jette

2016-01-01

The objective of this study was to develop a rapid, sensitive, and specific analytical method to study vitamin K-1 in fruits and vegetables. Accelerated solvent extraction and solid phase extraction was used for sample preparation. Quantification was done by liquid chromatography tandem mass...... spectrometry with atmospheric pressure chemical ionization in selected reaction monitoring mode with deuterium-labeled vitamin K1 as an internal standard. The precision was estimated as the pooled estimate of three replicates performed on three different days for spinach, peas, apples, banana, and beetroot...

Persistent Identifier Practice for Big Data Management at NCI

Directory of Open Access Journals (Sweden)

Jingbo Wang

2017-04-01

Full Text Available The National Computational Infrastructure (NCI manages over 10 PB research data, which is co-located with the high performance computer (Raijin and an HPC class 3000 core OpenStack cloud system (Tenjin. In support of this integrated High Performance Computing/High Performance Data (HPC/HPD infrastructure, NCI’s data management practices includes building catalogues, DOI minting, data curation, data publishing, and data delivery through a variety of data services. The metadata catalogues, DOIs, THREDDS, and Vocabularies, all use different Uniform Resource Locator (URL styles. A Persistent IDentifier (PID service provides an important utility to manage URLs in a consistent, controlled and monitored manner to support the robustness of our national ‘Big Data’ infrastructure. In this paper we demonstrate NCI’s approach of utilising the NCI’s 'PID Service 'to consistently manage its persistent identifiers with various applications.

Alkali suppression within laser ion-source cavities and time structure of the laser ionized ion-bunches

CERN Document Server

Lettry, Jacques; Köster, U; Georg, U; Jonsson, O; Marzari, S; Fedosseev, V

2003-01-01

The chemical selectivity of the target and ion-source production system is an asset for Radioactive Ion-Beam (RIB) facilities equipped with mass separators. Ionization via laser induced multiple resonant steps Ionization has such selectivity. However, the selectivity of the ISOLDE Resonant Ionization Laser Ion-Source (RILIS), where ionization takes place within high temperature refractory metal cavities, suffers from unwanted surface ionization of low ionization potential alkalis. In order to reduce this type of isobaric contaminant, surface ionization within the target vessel was used. On-line measurements of the efficiency of this method is reported, suppression factors of alkalis up to an order of magnitude were measured as a function of their ionization potential. The time distribution of the ion bunches produced with the RILIS was measured for a variety of elements and high temperature cavity materials. While all ions are produced within a few nanoseconds, the ion bunch sometimes spreads over more than 1...

Determination of ultra-low levels of uranium using resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Kiran Kumar, P.V.; Acharyulu, G.V.S.G.

2015-01-01

The determination of isotopic composition of actinides like U and Pu is important, due to their distribution in the environment as a result of nuclear weapons testing, fuel reprocessing, reactor operations and to a smaller extent from accidental releases. The analytical methods like fission track analysis (FTA), thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS) and resonance ionization mass spectrometry (RIMS) have evolved as sensitive techniques. Resonance Ionization Mass Spectrometry yields rapid isotopic signature data for material containing actinides without requiring time-consuming sample preparation and chemical separation procedures. In this paper, authors presented the details of the methodology and results for low-level detection of uranium using RIMS

Chemical changes in food packaging resulting from ionizing irradiation

International Nuclear Information System (INIS)

Thayer, D.W.

1988-01-01

Recent approvals of food irradiation processes by the U.S. Food and Drug Administration have led to a search for packaging approved for use with ionizing radiation. Though 13 packaging materials were approved several years ago as food contactants for gamma irradiation up to 10 kGy at refrigeration temperatures and 4 packaging materials were approved for up to 60 kGy at cryogenic temperatures, no currently used packaging is approved for irradiated foods. Extensive research was conducted by the U.S. Army and others on the suitability of both flexible packaging and metal cans for packaging irradiated foods. The results of the studies of packaging for irradiated foods will be described and discussed in context of currently used packaging materials for non-irradiated meats and poultry

Approaches for protection standards for ionizing radiation and combustion pollutants

International Nuclear Information System (INIS)

Butler, G.C.

1978-01-01

The question ''can the approach used for radiation protection standards, i.e., to extrapolate dose--response relationships to low doses, be applied to combustion pollutants'' provided a basis for discussion. The linear, nonthreshold model postulated by ICRP and UNSCEAR for late effects of ionizing radiation is described and discussed. The utility and problems of applying this model to the effects of air pollutants constitute the focus of this paper. The conclusion is that, in the absence of evidence to the contrary, one should assume the same type of dose--effect relation for chemical air pollutants as for ionizing radiation

Malalties de transmissió sexual a urgències pediàtriques

OpenAIRE

Díaz Sabogal, Diana; Curcoy Barcenilla, Ana Isabel; Trenchs Sainz de la Maza, Victoria; Giménez Roca, Clara; Luaces Cubells, Carles

2014-01-01

Determinar les característiques dels pacients diag- nosticats de malalties de transmissió sexual (MTS) a urgèn- cies i establir la freqüència en què són degudes a abús sexual. Mètode. Estudi retrospectiu fet entre el gener del 2007 i el desembre del 2011. S'inclouen els pacients menors de 18 anys diagnosticats a urgències d'MTS -infecció per Neisse- ria gonorrhoeae, Chlamydia trachomatis, Treponema palli- dum, , virus d'immunodeficiència humana (VIH), virus del pa- pil loma humà (VPH) i virus...

Determination of equilibrium composition of thermally ionized monoatomic gas under different physical conditions

Science.gov (United States)

Romanova, M. S.; Rydalevskaya, M. A.

2017-05-01

Perfect gas mixtures that result from thermal ionization of spatially and chemically homogeneous monoatomic gases are considered. Equilibrium concentrations of the components of such mixtures are determined using integration over the momentum space and summation with respect to energy levels of the distribution functions that maximize the entropy of system under condition for constancy of the total number of nuclei and electrons. It is demonstrated that such a method allows significant simplification of the calculation of the equilibrium composition for ionized mixtures at different temperatures and makes it possible to study the degree of ionization of gas versus gas density and number in the periodic table of elements.

The Enceladus Ionizing Radiation Environment: Implications for Biomolecules

Science.gov (United States)

Teodoro, L. A.; Elphic, R. C.; Davila, A. F.; McKay, C.; Dartnell, L.

2016-12-01

Enceladus' subsurface ocean is a possible abode for life, but it is inaccessible with current technology. However, icy particles and vapor are being expelled into space through surface fractures known as Tiger Stripes, forming a large plume centered in the South Polar Terrains. Direct chemical analyses by Cassini have revealed salts and organic compounds in a significant fraction of plume particles, which suggests that the subsurface ocean is the main source of materials in the plume (i.e. frozen ocean spray). While smaller icy particles in the plume reach escape velocity and feed Saturn's E-ring, larger particles fall back on the moon's surface, where they accumulate as icy mantling deposits at practically all latitudes. The organic content of these fall-out materials could be of great astrobiological relevance. Galactic Cosmic Rays (GCRs) that strike both Enceladus' surface and the lofted icy particles produce ionizing radiation in the form of high-energy electrons, protons, gamma rays, neutrons and muons. An additional source of ionizing radiation is the population of energetic charged particles in Saturn's magnetosphere. The effects of ionizing radiation in matter always involve the destruction of chemical bonds and the creation of free radicals. Both affect organic matter, and can damage or destroy biomarkers over time. Using ionizing radiation transport codes, we recreated the radiation environment on the surface of Enceladus, and evaluated its possible effects on organic matter (including biomarkers) in the icy mantling deposits. Here, we present full Monte-Carlo simulations of the nuclear reactions induced by the GCRs hitting Enceladus's surface using a code based on the GEANT-4 toolkit for the transport of particles. To model the GCR primary spectra for Z= 1-26 (protons to iron nuclei) we assumed the CREAME96 model under solar minimum, modified to take into account Enceladus' location. We considered bulk compositions of: i) pure water ice, ii) water ice

Selectivity of primary events in the radiation chemistry of organic solids and polymers as revealed by model studies of ionized molecules

International Nuclear Information System (INIS)

Feldman, V.

2006-01-01

Selectivity of the primary chemical events induced by ionizing radiation in molecular systems is the key issue of basic radiation chemistry, which is crucially important for controlling the radiation sensitivity of various-type organic and polymeric materials and designing new effective approaches to the radiation modification. In the past decade we have demonstrated that many features of selective localization of the radiation-induced effects in molecular solids can be understood on the basis of model studies of the primary ionized molecules in rigid low-temperature matrices. This talk will outline the key results of these studies and possible implications for radiation chemistry of vatious systems. In particular, the following aspects will be considered: (1) Spectroscopic characteristics of ustable ionized molecules in low-temperature matrices and their correlations with the site-selective reactivity. (2) Experimental modeling of the effect of excess energy on the properties of primary ionized molecules in condensed phases. (3) Intramolecular long-range effects with particular impact on the properties of ionized bifunctional molecules of X-(CH 2 ) n -X and X-(CH 2 ) n -Y types. (4) Modeling of intermolecular long-range positive hole transfer between molecular traps with close ionization energy and manifestations of 'fine tuning' effects resulting from conformation variations and intermolecular interactions. Several illustrative examples of correlation between the properties of primary ionized molecules and selectivity of the radiation-chemical transformations in organic solids and macromolecules will be presented. Finally, the problem of prediction of the radiation-chemical behaviour of complex organic systems on the basis of limited spectroscopic information and quantum-chemical data obtained for model systems will be addressed. This work was supported by the Russian Foundation for Basic Research (Project No. 06-03-33104) and the Russian Academy of Sciences

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

Science.gov (United States)

Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

2015-09-03

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. Copyright © 2015. Published by Elsevier B.V.

Chemical reaction due to stronger Ramachandran interaction

Indian Academy of Sciences (India)

actions between two polarized atoms are responsible for initiating a chemical reaction, either before or after ... Chemical reaction; Ramachandran interaction; anisotropic and asymmetric polarization; ionization ..... man sequence exactly, including the generalized mech- ..... We now move on and rearrange Eq. (8) to arrive at.

Sensitive method for the determination of nitrated polycyclic aromatic hydrocarbons in the human diet

Energy Technology Data Exchange (ETDEWEB)

Siegmund, B.; Weiss, R.; Pfannhauser, W. [Graz Univ. of Technology (Austria). Inst. of Food Chemistry

2003-01-01

The presence of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) as contaminants in foods is nowadays a legitimate cause of concern, as they are reported to be strong direct-acting mutagens and carcinogens that may pose a risk to human health. Nevertheless, their concentrations in foods are in the ultra-trace region. In this study, we present a very sensitive analytical method for the determination of this compound class in complex food matrices. Special emphasis was put on sample extraction and clean up. Recoveries of 75% could be obtained for 1- and 2-nitronaphthalene; for all other compounds investigated the recoveries were {>=}94%. The determination of the compounds was performed by gas chromatography-mass spectrometry. The results show that the use of negative chemical ionization (NCI) increases the sensitivity by one order of magnitude in comparison to electron impact ionization (EI) (limits of detection 0.07-0.25 {mu}g kg{sup -1} for EI and 0.01-0.02 {mu}g kg{sup -1} for NCI). The influence of the sample matrix on the sensitivity of the method is demonstrated with extracts of a sample from a duplicate diet study. Due to the lack of a certified reference material the suitability of the method is demonstrated with pumpkin seed oil that was spiked with nitro-PAHs at two different concentration levels. (orig.)

Ionization photophysics and spectroscopy of cyanoacetylene

Energy Technology Data Exchange (ETDEWEB)

Leach, Sydney; Champion, Norbert [LERMA UMR CNRS 8112, Observatoire de Paris-Meudon, 5 place Jules-Jansen, 92195 Meudon (France); Garcia, Gustavo A.; Fray, Nicolas; Gaie-Levrel, François [Synchrotron SOLEIL, L’Orme des Merisiers, St. Aubin, B.P. 48, 91192, Gif-sur-Yvette Cedex (France); Mahjoub, Ahmed; Bénilan, Yves; Gazeau, Marie-Claire; Schwell, Martin [LISA UMR CNRS 7583, Université Paris Est Créteil and Université Paris Diderot, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil (France)

2014-05-07

Photoionization of cyanoacetylene was studied using synchrotron radiation over the non-dissociative ionization excitation range 11–15.6 eV, with photoelectron-photoion coincidence techniques. The absolute ionization cross-section and spectroscopic aspects of the parent ion were recorded. The adiabatic ionization energy of cyanoacetylene was measured as 11.573 ± 0.010 eV. A detailed analysis of photoelectron spectra of HC{sub 3}N involves new aspects and new assignments of the vibrational components to excitation of the A{sup 2}Σ{sup +} and B{sup 2}Π states of the cation. Some of the structured autoionization features observed in the 11.94 to 15.5 eV region of the total ion yield (TIY) spectrum were assigned to two Rydberg series converging to the B{sup 2}Π state of HC{sub 3}N{sup +}. A number of the measured TIY features are suggested to be vibrational components of Rydberg series converging to the C{sup 2}Σ{sup +} state of HC{sub 3}N{sup +} at ≈17.6 eV and others to valence shell transitions of cyanoacetylene in the 11.6–15 eV region. The results of quantum chemical calculations of the cation electronic state geometries, vibrational frequencies and energies, as well as of the C–H dissociation potential energy profiles of the ground and electronic excited states of the ion, are compared with experimental observations. Ionization quantum yields are evaluated and discussed and the problem of adequate calibration of photoionization cross-sections is raised.

Closing in on chemical bonds by opening up relativity theory.

Science.gov (United States)

Whitney, Cynthia K

2008-03-01

This paper develops a connection between the phenomenology of chemical bonding and the theory of relativity. Empirical correlations between electron numbers in atoms and chemical bond stabilities in molecules are first reviewed and extended. Quantitative chemical bond strengths are then related to ionization potentials in elements. Striking patterns in ionization potentials are revealed when the data are viewed in an element-independent way, where element-specific details are removed via an appropriate scaling law. The scale factor involved is not explained by quantum mechanics; it is revealed only when one goes back further, to the development of Einstein's special relativity theory.

Effect of ionizing radiation on starch and cellulose

International Nuclear Information System (INIS)

Klenha, J.; Bockova, J.

1973-09-01

The investigation is reported of the effects of ionizing radiation both on macromolecular systems generally and on polysaccharides, starch and cellulose. Attention is focused on changes in the physical and physico-chemical properties of starch and cellulose, such as starch swelling, gelation, viscosity, solubility, reaction with iodine, UV, IR and ESR spectra, chemical changes resulting from radiolysis and from the effect of amylases on irradiated starch, changes in cellulose fibre strength, water absorption, stain affinity, and also the degradation of cellulose by radiation and the effect of cellulases on irradiated cellulose. Practical applications of the findings concerning cellulose degradation are discussed. (author)

Study of physical, chemical and structural effects caused by ionizing radiation and preservation on human costal cartilage

International Nuclear Information System (INIS)

Martinho Junior, Antonio Carlos

2008-01-01

Tissue Banks around the world have stored human cartilages obtained from cadaver donors for use in several kinds of reconstructive surgeries. To ensure that such tissues are not contaminated, they have been sterilized with ionizing radiation. However, high doses of gamma radiation may cause undesirable changes in the tissues, decreasing the mechanical properties of the grafts. In this work, we evaluate physical/chemical and structural changes in deep-frozen (-70 deg C) or high concentration of glycerol (> 98%) preserved costal cartilage, before and after sterilization by ionizing radiation at 3 different doses (15, 25 and 50 kGy). Samples of human costal cartilage were obtained from 20 cadaver donors ranging between 18 and 55 years old. A 60 Co irradiator was used as irradiation source. Thermogravimetry (TG), Optical Coherence Tomography (OCT) and mechanical tension and compression tests were carried out to evaluate the changes in the cartilage. Regarding the thermogravimetric results, the obtained data has shown that the TG curves have the same pattern independently of the sample irradiated or not. On the other hand, non-irradiated samples showed great variability of thermogravimetric curves among different donors and for the same donor. Concerning the mechanical tests, when cartilages were irradiated with 15 kGy, their mechanical strength to tension was increased about 24%, in both deep-froze and preserved in glycerol samples. Samples deep-frozen, when irradiated with 25 and 50 kGy, presented a decrease of their mechanical behavior smaller than those preserved in high concentrations of glycerol and irradiated with the same dose. Therefore, deep-frozen cartilages can be sterilized with doses until 50 kGy and cartilages preserved in high concentrations of glycerol can be sterilized with doses until 25 kGy without significant changes in their bio-mechanical properties.(author)

Ring magnetron ionizer

International Nuclear Information System (INIS)

Alessi, J.G.

1986-01-01

A ring magnetron D - charge exchange ionizer has been built and tested. An H - current of 500 μA was extracted with an estimated H 0 density in the ionizer of 10 12 cm -3 . This exceeds the performance of ionizers presently in use on polarized H - sources. The ionizer will soon be tested with a polarized atomic beam

Analysis of chemical degradation mechanism of phosphorescent organic light emitting devices by laser-desorption/ionization time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Rabelo de Moraes, Ines; Scholz, Sebastian; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden (Germany)

2010-07-01

Phosphorescent organic light emitting diodes (OLEDs) have attracted much interest for their potential application in full color flat-panel displays and as an alternative lighting source. However, low efficiency, and the short operation lifetime, in particular in the case of blue emitting devices, are the major limitations for the current OLEDs commercialization. In order to overcome these limitations, a deep knowledge about the aging and the degradation mechanism is required. Our work focuses on the chemical degradation mechanism of different iridium based emitter materials like FIrpic (light blue) and Ir(ppy)3 (green), commonly used in OLEDs. For this purpose, the devices were aged by electrical driving until the luminance reached 6% of the initial luminance. The laser-desorption/ionization time-of-flight mass spectrometry was used to determine specific degradation pathways.

Chemical inhibition of cell recovery after irradiation with sparsely and densely ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Evastratova, Ekaterina S.; Petin, Vladislav [A. Tsyb Medical Radiological Research Centre-branch of the National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Obninsk (Russian Federation); Kim, Jin Hong; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Advanced Radiation Technology Institute (ARTI), Jeongeup (Korea, Republic of); Lim, Youg Khi [Dept. of Radiological Science, Gachon University, Incheon (Korea, Republic of)

2017-02-15

The dependence of cell survival on exposure dose and the duration of the liquid holding recovery (LHR) was obtained for diploid yeast cells irradiated with ionizing radiation of different linear energy transfer (LET) and recovering from radiation damage without and with various concentrations of cisplatin - the most widely used anticancer drug. The ability of yeast cells to recover from radiation damage was less effective after cell exposure to high-LET radiation, when cells were irradiated without drug. The increase in cisplatin concentration resulted in the disappearance of this difference whereas the fraction of irreversible damage was permanently enlarged independently of radiation quality. The probability of cell recovery was shown to be constant for various conditions of irradiation and recovery. A new mechanism of cisplatin action was suggested according with which the inhibition of cell recovery after exposure to ionizing radiations was completely explained by the production of irreversible damage.

Chemical inhibition of cell recovery after irradiation with sparsely and densely ionizing radiation

International Nuclear Information System (INIS)

Evastratova, Ekaterina S.; Petin, Vladislav; Kim, Jin Hong; Kim, Jin Kyu; Lim, Youg Khi

2017-01-01

The dependence of cell survival on exposure dose and the duration of the liquid holding recovery (LHR) was obtained for diploid yeast cells irradiated with ionizing radiation of different linear energy transfer (LET) and recovering from radiation damage without and with various concentrations of cisplatin - the most widely used anticancer drug. The ability of yeast cells to recover from radiation damage was less effective after cell exposure to high-LET radiation, when cells were irradiated without drug. The increase in cisplatin concentration resulted in the disappearance of this difference whereas the fraction of irreversible damage was permanently enlarged independently of radiation quality. The probability of cell recovery was shown to be constant for various conditions of irradiation and recovery. A new mechanism of cisplatin action was suggested according with which the inhibition of cell recovery after exposure to ionizing radiations was completely explained by the production of irreversible damage

Document authentication at molecular levels using desorption atmospheric pressure chemical ionization mass spectrometry imaging.

Science.gov (United States)

Li, Ming; Jia, Bin; Ding, Liying; Hong, Feng; Ouyang, Yongzhong; Chen, Rui; Zhou, Shumin; Chen, Huanwen; Fang, Xiang

2013-09-01

Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS), which was operated in either a gasless, solvent-free or methanol vapor-assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI-MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI-MS imaging differentiated a 10-min old from two 4 h old samples. Non-destructive forensic analysis of forged signatures either handwritten or computer-assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI-MS. The experimental results show that DAPCI-MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications. © 2013 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd.

Analysis of laser ablation: Contribution of ionization energy to the plasma and shock wave properties

International Nuclear Information System (INIS)

Wen, S.-B.; Mao Xianglei; Greif, Ralph; Russo, Richard E.

2007-01-01

By fitting simulation results with experimentally measured trajectories of the shock wave and the vapor/background gas contact surface, we found that inclusion of ionization energy in the analysis leads to a change in the evolution of the pressure, mass density, electron number density, and temperature of the vapor plume. The contribution of ionization energy to both the plasma and shock wave has been neglected in most studies of laser ablation. Compared to previous simulations, the densities, pressures, and temperatures are lower shortly after the laser pulse ( 50 ns). The predicted laser energy conversion ratio also showed about a 20% increase (from 35% to 45%) when the ionization energy is considered. The changes in the evolution of the physical quantities result from the retention of the ionization energy in the vapor plume, which is then gradually transformed to kinetic and thermal energies. When ionization energy is included in the simulation, the vapor plume attains higher expansion speeds and temperatures for a longer time after the laser pulse. The better determination of the temperature history of the vapor plume not only improves the understanding of the expansion process of the laser induced vapor plume but also is important for chemical analysis. The accurate temperature history provides supplementary information which enhances the accuracy of chemical analysis based on spectral emission measurements (e.g., laser induced breakdown spectroscopy)

NCI Helps Children’s Hospital of Philadelphia to Identify and Treat New Target in Pediatric Cancer | Poster

Science.gov (United States)

There may be a new, more effective method for treating high-risk neuroblastoma, according to scientists at the Children’s Hospital of Philadelphia and collaborators in the Cancer and Inflammation Program at NCI at Frederick. Together, the groups published a study describing a previously unrecognized protein on neuroblastoma cells, called GPC2, as well as the creation of a

ACToR Chemical Structure processing using Open Source ...

Science.gov (United States)

ACToR (Aggregated Computational Toxicology Resource) is a centralized database repository developed by the National Center for Computational Toxicology (NCCT) at the U.S. Environmental Protection Agency (EPA). Free and open source tools were used to compile toxicity data from over 1,950 public sources. ACToR contains chemical structure information and toxicological data for over 558,000 unique chemicals. The database primarily includes data from NCCT research programs, in vivo toxicity data from ToxRef, human exposure data from ExpoCast, high-throughput screening data from ToxCast and high quality chemical structure information from the EPA DSSTox program. The DSSTox database is a chemical structure inventory for the NCCT programs and currently has about 16,000 unique structures. Included are also data from PubChem, ChemSpider, USDA, FDA, NIH and several other public data sources. ACToR has been a resource to various international and national research groups. Most of our recent efforts on ACToR are focused on improving the structural identifiers and Physico-Chemical properties of the chemicals in the database. Organizing this huge collection of data and improving the chemical structure quality of the database has posed some major challenges. Workflows have been developed to process structures, calculate chemical properties and identify relationships between CAS numbers. The Structure processing workflow integrates web services (PubChem and NIH NCI Cactus) to d

Determination of composition and physical properties of partially ionized plasmas in the function of temperature

International Nuclear Information System (INIS)

Zaporowski, B.

1992-01-01

The investigations of various kinds of partially ionized plasma were conducted for the pressure of 0.1 MPa and in the range of temperature of 298.15 K to 24000 K. The physical properties of various kinds of partially ionized plasma depend mainly of their composition and temperature. The composition of particular kinds of partially ionized plasmas varies also in the function of temperature. Simultaneous going on of physical and chemical processes in plasma is the reason of difficulties in the calculations of plasma's physical properties. The use of the laws of macroscopic thermodynamics for the calculations of physical properties of partially ionized plasma is impossible. There are enough exact methods for measuring of physical properties of partially ionized plasma. For these reasons the theoretical method using the base of statistic physics was used to calculate the composition and physical properties of various kinds of partially ionized plasma. (author) 2 refs., 2 figs

Chemical effects and their consequences for individuals occupationally exposed to ionizing radiation; Efeitos químicos e suas consequências para indivíduos ocupacionalmente expostos à radiação ionizante

Energy Technology Data Exchange (ETDEWEB)

Salvador, C.; Kahl, G.G.; Kühn, P.; Zottis, A.D.; Flôr, R.C., E-mail: carolinesalvador09@gmail.com [Instituto Federal de Educação, Ciência e Tecnologia de Santa Catarina (IFSC), Florianópolis (Brazil). Departamento Acadêmico de Saúde e Serviços

2017-07-01

By legal determination, workers exposed to ionizing radiation should use individual dosimeters in the most exposed region of the body, designed to estimate the effective dose, as well as radiation protective clothing to minimize occupational exposures. Regarding dosimetry, in most cases it is perceived that the monthly values of exposure are within the limits of normality, however, even being below the limit can not rule out the possibility of damage that the low dose of ionizing radiation can cause. The objective of this article is to highlight the main chemical effects caused by exposure to ionizing radiation, especially biochemical damage in DNA, chromosomal aberrations and the correlation with the exposure of occupationally exposed individuals, as well as individuals from the public. A bibliographic search was carried out in indexed databases from February to April 2017 with the following descriptors: Radiation Ionizing, DNA Damage and Occupational Exposure. In the 'Science Direct' database were found 1205 articles, in the 'Scopus' 19 articles, in the 'Web of Science' 83 articles, in the 'PubMed' 22 articles and in the 'VHL' 60 articles related to the theme. It was concluded that exposure to ionizing radiation can affect the DNA molecule despite its repair mechanisms, which may result in genotoxicity. It has been reported a correlation between occupationally exposed individuals and chromosomal aberrations, demonstrating that even low doses of ionizing radiation can compromise the genetic material integrity of exposed workers, leading to the need for a periodic cytogenetic study for this group of workers.

Thermionic detector with multiple layered ionization source

International Nuclear Information System (INIS)

Patterson, P. L.

1985-01-01

Method and apparatus for analyzing specific chemical substances in a gaseous environment comprises a thermionic source formed of multiple layers of ceramic material composition, an electrical current instrumentality for heating the thermionic source to operating temperatures in the range of 100 0 C. to 1000 0 C., an instrumentality for exposing the surface of the thermionic source to contact with the specific chemical substances for the purpose of forming gas phase ionization of the substances by a process of electrical charge emission from the surface, a collector electrode disposed adjacent to the thermiomic source, an instrumentality for biasing the thermionic source at an electrical potential which causes the gas phase ions to move toward the collector, and an instrumentality for measuring the ion current arriving at the collector. The thermionic source is constructed of a metallic heater element molded inside a sub-layer of hardened ceramic cement material impregnated with a metallic compound additive which is non-corrosive to the heater element during operation. The sub-layer is further covered by a surface-layer formed of hardened ceramic cement material impregnated with an alkali metal compound in a manner that eliminates corrosive contact of the alkali compounds with the heater element. The sub-layer further protects the heater element from contact with gas environments which may be corrosive. The specific ionization of different chemical substances is varied over a wide range by changing the composition and temperature of the thermionic source, and by changing the composition of the gas environment

Analysis of polycyclic aromatic hydrocarbons using desorption atmospheric pressure chemical ionization coupled to a portable mass spectrometer.

Science.gov (United States)

Jjunju, Fred P M; Maher, Simon; Li, Anyin; Badu-Tawiah, Abraham K; Taylor, Stephen; Cooks, R Graham

2015-02-01

Desorption atmospheric pressure chemical ionization (DAPCI) is implemented on a portable mass spectrometer and applied to the direct detection of polycyclic aromatic hydrocarbons (PAHs) and alkyl substituted benzenes. The presence of these compounds in the environment poses a significant threat to the health of both humans and wildlife because of their carcinogenic, toxic, and mutagenic properties. As such, instant detection outside of the laboratory is of particular importance to allow in-situ measurement at the source. Using a rapid, high throughput, miniature, handheld mass spectrometer, several alkyl substituted benzenes and PAHs (i.e., 1,2,3,5-tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, fluoranthene, anthracene, benzo[k]fluoranthene, dibenz[a,h]anthracene, acenaphthene, indeno[1,2,3-c,d]pyrene, 9-ethylfluorene, and 1-benzyl-3-methyl-naphthalene) were identified and characterized using tandem mass spectrometry (MS/MS) from ambient surfaces, in the open air. This method can provide almost instantaneous information while minimizing sample preparation, which is advantageous in terms of both cost and simplicity of analysis. This MS-based technique is applicable to a wide range of environmental organic molecules.

Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

International Nuclear Information System (INIS)

Blashenkov, Nikolai M; Lavrent'ev, Gennadii Ya

2007-01-01

The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied. (instruments and methods of investigation)

Atmospheric Ionizing Radiation (AIR) ER-2 Preflight Analysis

Science.gov (United States)

Tai, Hsiang; Wilson, John W.; Maiden, D. L.

1998-01-01

Atmospheric ionizing radiation (AIR) produces chemically active radicals in biological tissues that alter the cell function or result in cell death. The AIR ER-2 flight measurements will enable scientists to study the radiation risk associated with the high-altitude operation of a commercial supersonic transport. The ER-2 radiation measurement flights will follow predetermined, carefully chosen courses to provide an appropriate database matrix which will enable the evaluation of predictive modeling techniques. Explicit scientific results such as dose rate, dose equivalent rate, magnetic cutoff, neutron flux, and air ionization rate associated with those flights are predicted by using the AIR model. Through these flight experiments, we will further increase our knowledge and understanding of the AIR environment and our ability to assess the risk from the associated hazard.

Carbon Nanotube Fiber Ionization Mass Spectrometry: A Fundamental Study of a Multi-Walled Carbon Nanotube Functionalized Corona Discharge Pin for Polycyclic Aromatic Hydrocarbons Analysis

Science.gov (United States)

Nahan, Keaton S.; Alvarez, Noe; Shanov, Vesselin; Vonderheide, Anne

2017-09-01

Mass spectrometry continues to tackle many complicated tasks, and ongoing research seeks to simplify its instrumentation as well as sampling. The desorption electrospray ionization (DESI) source was the first ambient ionization source to function without extensive gas requirements and chromatography. Electrospray techniques generally have low efficiency for ionization of nonpolar analytes and some researchers have resorted to methods such as direct analysis in real time (DART) or desorption atmospheric pressure chemical ionization (DAPCI) for their analysis. In this work, a carbon nanotube fiber ionization (nanoCFI) source was developed and was found to be capable of solid phase microextraction (SPME) of nonpolar analytes as well as ionization and sampling similar to that of direct probe atmospheric pressure chemical ionization (DP-APCI). Conductivity and adsorption were maintained by utilizing a corona pin functionalized with a multi-walled carbon nanotube (MWCNT) thread. Quantitative work with the nanoCFI source with a designed corona discharge pin insert demonstrated linearity up to 0.97 (R2) of three target PAHs with phenanthrene internal standard. [Figure not available: see fulltext.

The identification of autoionizing states of atomic chromium for the resonance ionization laser ion source of the ISOLDE radioactive ion beam facility

CERN Document Server

Goodacre, T Day

2017-01-01

The resonance ionization laser ion source (RILIS) is the principal ion source of the ISOLDE radioactive beam facility based at CERN. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-resonance photo-ionization scheme has been developed for chromium. The scheme uses an ionizing transition to one of the 14 newly observed autoionizing states. This work increases the range of ISOLDE-RILIS ionized beams to 32 chemical elements. Details of the spectroscopic studies are described and the new ionization scheme is summarized. A link to the complete version of this document will be added here following publication:

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids.

Science.gov (United States)

Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J

2016-02-04

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. Copyright © 2015 Elsevier B.V. All rights reserved.

Computational Calculation Of The Ionization Energies Of The Human Prion Protein By The Coarse-grain Method

Science.gov (United States)

Lyu, Justin; Andrianarijaona, V. M.

2016-05-01

The causes of the misfolding of prion protein -i.e. the transformation of PrPC to PrPSc - have not been clearly elucidated. Many studies have focused on identifying possible chemical conditions, such as pH, temperature and chemical denaturation, that may trigger the pathological transformation of prion proteins (Weiwei Tao, Gwonchan Yoon, Penghui Cao, `` β-sheet-like formation during the mechanical unfolding of prion protein'', The Journal of Chemical Physics, 2015, 143, 125101). Here, we attempt to calculate the ionization energies of the prion protein, which will be able to shed light onto the possible causes of the misfolding. We plan on using the coarse-grain method which allows for a more feasible calculation time by means of approximation. We believe that by being able to approximate the ionization potential, particularly that of the regions known to form stable β-strands of the PrPSc form, the possible sources of denaturation, be it chemical or mechanical, may be narrowed down.

Proton-therapy and hadron-therapy ionization chambers

International Nuclear Information System (INIS)

Boissonnat, Guillaume

2015-01-01

In the framework of the ARCHADE project (Advanced Resource Center for Hadron-therapy in Europe), a research project in Carbone ion beam therapy and clinical Proton-therapy, this work investigates the beam monitoring and dosimetry aspects of ion beam therapy. The main goal, here, is to understand the operating mode of air ionization chambers, the detectors used for such applications. This study starts at a very fundamental level as the involved physical and chemical parameters of air were measured in various electric field conditions with dedicated setups and used to produce a simulation tools aiming at reproducing the operating response in high intensity PBS (Pencil Beam Scanning) coming from IBA's (Ion Beam Applications) next generation of proton beam accelerators. In addition, an ionization chamber-based dosimetry equipment was developed, DOSION III, for radiobiology studies conducted at GANIL under the supervision of the CIMAP laboratory. (author)

Plant collecting program in Southeast Asia under the sponsorship of the United States National Cancer Institute (NCI) (1986-1991)

NARCIS (Netherlands)

Soejarto, D.D.

1992-01-01

Under the funding from the United States National Cancer Institute (NCI)¹, a program was undertaken to collect plant samples in Southeast Asia to be tested for their cancer- and AIDS-arresting properties, for the period of September 1, 1986 through August 31, 1991. The program was implemented with

Observations and Modeling of the Green Ocean Amazon 2014/15: Hydroxyl Radical (OH) Chemical Ionization Mass Spectrometer (CIMS) Field Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Kim, Saewung [Univ. of California, Irvine, CA (United States)

2016-05-01

The University of California, Irvine, science team (Dr. Saewung Kim, Dr. Roger Seco, Dr. Alex Guenther, and Dr. Jim Smith) deployed a chemical ionization mass spectrometer system for hydroxyl radical (OH) and sulfuric acid quantifications. As part of the GoAmazon 2014/15 field campaign. Hydroxyl radical determines tropospheric oxidation capacity and had been expected to be very low in the pristine rain forest region such as the Brazilian Amazon because of the presence of significant levels of highly reactive biogenic volatile organic compounds and very low levels of NO, which is an OH recycling agent. However, several recent in situ OH observations provided by a laser-induced fluorescence system reported unaccountably high OH concentrations. To address this discrepancy, a series of laboratory and theoretical studies has postulated chemical reaction mechanisms of isoprene that may regenerate OH in photo-oxidation processes. Along with these efforts, potential artifacts on the laser induced fluorescence system from isoprene and its oxidation products also have been explored. Therefore, the first chemical ionization mass spectrometer observations at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s T3 site in Manacapuru, Brazil, are expected to provide a critical experimental constraint to address uncertainty in constraining oxidation capacity over pristine rain forest environments. In addition, we deployed a National Center for Atmospheric Research (NCAR) proton transfer reaction time-of-flight mass spectrometer to characterize atmospheric volatile organic compound levels, especially isoprene and its oxidation products, which are critical input parameters for box modeling to simulate OH with different isoprene photo-oxidation schemes. As there has been no report on noticeable new particle formation events, our first in situ sulfuric acid observations in the Amazon rain forest were expected to constrain the

Evaluation of ionizing radiation effects in bone tissue by FTIR spectroscopy and dynamic mechanical analysis

International Nuclear Information System (INIS)

Veloso, Marcelo N.; Santin, Stefany P.; Benetti, Carolina; Pereira, Thiago M.; Mattor, Monica B.; Politano, Rodolfo; Zezell, Denise M.

2013-01-01

In many medical practices the bone tissue exposure to ionizing radiation is necessary. However, this radiation can interact with bone tissue in a molecular level, causing chemical and mechanical changes related with the dose used. The aim of this study was verify the changes promoted by different doses of ionizing radiation in bone tissue using spectroscopy technique of Attenuate Total Reflectance - Fourier Transforms Infrared (ATR-FTIR) and dynamic mechanical analysis. Samples of bovine bone were irradiated using irradiator of Cobalt-60 with five different doses between 0.01 kGy, 0.1 kGy,1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on bone chemical structure the sub-bands of amide I and the crystallinity index were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify if the chemical changes and the bone mechanic characteristics were related, it was made one study about the correlation between the crystallinity index and the elastic modulus, between the sub-bands ratio and the damping value and between the sub-bands ratio and the elastic modulus. It was possible to evaluate the effects of different dose of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy analysis, it was possible observe changes in the organic components and in the hydroxyapatite crystals organization. Changes were also observed in the mechanical properties. A good correlation between the techniques was found, however, it was not possible to establish a linear or exponential dependence between dose and effect. (author)

Ionization Potentials of Chemical Warfare Agents and Related Compounds Determined with Density Functional Theory

National Research Council Canada - National Science Library

Wright, J

2000-01-01

...) agents at contaminated sites. Reported herein are theoretical ionization potentials for CW agents and their related compounds calculated using density functional theory at the B3LYP/6-311+G(2d,p) level of theory...

Application of ionizing radiation in treatment of meat

International Nuclear Information System (INIS)

Sedlackova, J.

1984-01-01

Processes used for meat treatment for storage (cooling, radurization + cooling, freezing, heat treatment and radappertization) are compared with regard to energy demand. The effect of doses above 10 kGy and below 10 kGy are discussed. Doses of ionizing radiation may be combined with other techniques (heat treatment, the addition of certain chemicals or antibiotics). Czechoslovak experience with irradiation of meat with tapeworm cysticerci is described. (E.F.)

Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D2O ice beneath a H2O ice layer

International Nuclear Information System (INIS)

Yang, Rui; Gudipati, Murthy S.

2014-01-01

In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D 2 O ices by novel infrared (IR) laser ablation of a layered non-absorbing D 2 O ice (spectator) containing the analytes and an ablation-active IR-absorbing H 2 O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H 2 O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D 2 O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D 2 O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H 2 O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and ionization. This new technique

Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids.

Science.gov (United States)

Swider, Paweł; Lewtak, Jan P; Gryko, Daniel T; Danikiewicz, Witold

2013-10-01

The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free-base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography-MS experiments. Copyright © 2013 John Wiley & Sons, Ltd.

The mechanism for the primary biological effects of ionizing radiation

International Nuclear Information System (INIS)

Byakov, Vsevolod M; Stepanov, Sergei V

2006-01-01

The primary biological response of living organisms to the passage of fast charged particles is traditionally believed to be dominated by the chemical reactions of the radical products from the radiolysis of cellular water (OH, H, e aq - , O 2 - , H 2 O 2 ) and by the bioradicals that they produce (and which can also result from the direct electronic activation of biomolecules). This understanding has provided insight into how ionizing radiations affect biological systems and, most importantly, what radioprotection and radiosensibilizing effects are produced by chemical compounds introduced into an organism. However, a number of key radiobiological facts remain unexplained by the current theory, stimulating a search for other biologically active factors that may be triggered by radiation. This review examines a fact that is usually ignored in discussing the biological impact of ionizing radiation: the local increase in acidity in the water solution along the track of a charged particle. The acidity in the track is very different from its value for cellular water in a living organism. Biological processes are well-known to be highly sensitive to changes in the environmental acidity. It seems that the biological impact of ionizing radiations is dominated not by the water radiolysis products (mostly radicals) listed above but particles of a different nature, hydroxonium ions H 3 O + , where the term hydroxonium refer to protonated water molecules. This modification of the mechanism of primary radiobiological effects is in good agreement with experimental data. In particular, the extremal dependence of the relative biological efficiency (RBE) of radiations on their ionizing energy losses is accounted for in quantitative terms, as is the increase in the RBE in the relativistic energy range. (reviews of topical problems)

Ionization

International Nuclear Information System (INIS)

2002-01-01

This document reprints the text of the French by-law from January 8, 2002 relative to the approval and to the controls and verifications of facilities devoted to the ionizing of food products for human beings and animals. The by-law imposes the operators of such facilities to perform measurements and dosimetric verifications all along the ionization process. (J.S.)

Effects of ionizing radiation in the physico-chemical characteristics of red wine Cabernet Sauvignon; Efeitos da radiacao ionizante nas caracteristicas fisico-quimicas do vinho tinto Cabernet Sauvignon

Energy Technology Data Exchange (ETDEWEB)

Silva, Fellipe Souza da; Leiras, Anderson; Wagner, Walsan, E-mail: fellipe.souzadasilva@gmail.com [Instituto de Radioprotecao e Dosimetria, (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2014-07-01

The oenology in the current days is increasingly aimed obtain improvements on wine quality produced without there the deterioration of characteristics of the same, using new technologies for such order. The objective of present work will be the application of the radiation ionizing in wines Cabernet Sauvignon, with the interest of analyzing its effects on physic-chemical characteristics of this wines, such as quality, aging and etc. Were analyzed the following strands: degree alcoholic; dry extract; density and absorbance with spectrometer (420, 520 and 620 nm). (author)

Ionizing radiation

International Nuclear Information System (INIS)

Kruger, J.

1989-01-01

Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

Chemical effects of radiation

International Nuclear Information System (INIS)

Philips, G.O.

1986-01-01

Ionizing radiations initiate chemical changes in materials because of the high energy of their quanta. In water, highly reactive free radicals are produced which can initiate secondary changes of solutes, and in chemical of biological molecules in contact with the water. Free radicals can also be directly produced in irradiated medical products. Their fate can be identified and the molecular basis of radiation inactivation clarified. Methods have now been developed to protect and minimise such radiation damage. (author)

Electron ionization and the Compton effect in double ionization of helium

International Nuclear Information System (INIS)

Samson, J.

1994-01-01

The author discusses ionization phenomena in helium, both photoionization and electron ionization. In particular he compares double ionization cross sections with total cross sections, as a function of electron energy, and photon energy. Data is discussed over the energy range up to 10 keV

Application of spectroscopic methods to the study of ionizing radiation effects in polymers

International Nuclear Information System (INIS)

Jimenez P, G.

1995-01-01

In general the interaction of ionizing radiation with polymers generates physic-chemical changes. Aiming to quantity these changes, three spectroscopic analytical techniques were used (UV, IR and EPR) and the chemical corrosion technique was used for three DSTN (CR39, Lexan and Makrofol) which were exposed to two radiation types: electrons and gammas. The effects of radiation are compared. Also a correlation between the UV and Vg results in function of dose is presented. The possible causes of the increase in chemical corrosion are discussed. (Author)

On the mechanism of the biological effect of ionizing radiation

International Nuclear Information System (INIS)

Margulis, M.A.; Margulis, I.M.

2005-01-01

The mechanisms of the biological effects of ionizing radiation (IR) and ultrasound (US) were considered. The current views on the nature of toxicity of IR, which is usually assigned to the formation of radicals in living tissues and to the straight-line collision of an ionizing particle with the DNA molecule, were analyzed. It was established that the amount of radicals formed in biological tissues in conditions of ultrasonically induced cavitation can be as large as that for IR; however, the biological effect of US is much softer as compared to IR. It was shown that the contribution of the indirect mechanism to the total biological effect of IR can be estimated by comparing US and IR in their chemical action; the contribution of the indirect mechanism to the biological effect of IR was found to be negligibly small. An alternative mechanism was proposed to explain the biological effect of IR. In accordance with the proposed model, IR with a high linear energy transfer (LET) value breaks through cell walls and biological membranes and causes damage to them, such that the cell can lose its regenerative capacity. Moreover, high-energy heavy ionizing particles perforate cytoplasm to form channels. Ionizing radiation with a low LET value (γ- and X-rays) causes multiple damages to biological membranes. Ionizing particles can also cause damages to membranes of mitochondria thus affecting the mechanism of cellular respiration, which will cause neoplastic diseases. The straight-line collision of an ionizing particle with a DNA molecule was found to be 5-7 orders of magnitude less probable as compared to the collision with a wall or membrane. It was shown that multiple perforations of cell walls and damages to membranes are characteristic only of ionizing particles, which have sufficiently long tracks, and do not occur upon exposure to ultrasonic waves, microwaves, UV radiation, and magnetic fields [ru

Characterization of aromatic organosulfur model compounds relevant to fossil fuels by using atmospheric pressure chemical ionization with CS2 and high-resolution tandem mass spectrometry.

Science.gov (United States)

Tang, Weijuan; Sheng, Huaming; Jin, Chunfen; Riedeman, James S; Kenttämaa, Hilkka I

2016-04-15

The chemistry of desulfurization involved in processing crude oil is greatly dependent on the forms of sulfur in the oil. Sulfur exists in different chemical bonding environments in fossil fuels, including those in thiophenes and benzothiophenes, thiols, sulfides, and disulfides. In this study, the fragmentation behavior of the molecular ions of 17 aromatic organosulfur compounds with various functionalities was systematically investigated by using high-resolution tandem mass spectrometry. Multiple-stage tandem mass spectrometric experiments were carried out using a linear quadrupole ion trap (LQIT) equipped with an atmospheric pressure chemical ionization (APCI) source. (+)APCI/CS2 was used to generate stable dominant molecular ions for all the compounds studied except for three sulfides that also showed abundant fragment ions. The LQIT coupled with an orbitrap mass spectrometer was used for elemental composition analysis, which facilitated the identification of the neutral molecules lost during fragmentation. The characteristic fragment ions generated in MS(2) and MS(3) experiments provide clues for the chemical bonding environment of sulfur atoms in the examined compounds. Upon collision-induced dissociation (CID), the molecular ions can lose the sulfur atom in a variety of ways, including as S (32 Da), HS(•) (33 Da), H2 S (34 Da), CS (44 Da), (•) CHS (45 Da) and CH2 S (46 Da). These neutral fragments are not only indicative of the presence of sulfur, but also of the type of sulfur present in the compound. Generally, losses of HS(•) and H2 S were found to be associated with compounds containing saturated sulfur functionalities, while losses of S, CS and (•) CHS were more common for heteroaromatic sulfur compounds. High-resolution tandem mass spectrometry with APCI/CS2 ionization is a viable approach to determining the types of organosulfur compounds. It can potentially be applied to analysis of complex mixtures, which is beneficial to improving the

Micro Corona Ionizer as an Ozone Source for Bacterial Cell Lysis

Science.gov (United States)

Lee, Eun-Hee; Lim, Hyun Jeong; Chua, Beelee; Son, Ahjeong

2015-04-01

DNA extraction is a critical process of DNA assays including polymerase chain reaction (PCR), microarrays, molecular cloning, and DNA hybridization which has been well established and can be implemented by commercial kits. DNA extraction involves cell lysis, precipitation, and purification through the combination of physical and chemical processes. Cell lysis is essential to high DNA recovery yield which can be achieved via a variety of physical, chemical, and enzymatic methods. However, these methods were originally developed for bioassays that were labor intensive, time consuming, and vulnerable to contamination and inhibition. Here, we proposed to employ a micro corona ionizer as an ozone source to lyse bacterial cells. Ozone has been well known and used as a disinfectant which allows cell lysis and DNA extraction. Previously, we have shown that a micro corona ionizer is capable of generating a significant amount of ozone. In this study, we employed the micro corona ionizer for the bacterial cell lysis which consists of a 50 μm diameter cantilever wire as the discharge cathode and a 50 μm thick copper foil as anode. Applied voltages varied from 1900 to 2200 V with corresponding corona currents from 16 to 28 μA. The resultant ozone (concentration > 0.14 ppm) generated from the micro corona ionizer was bubbled into the sample via a miniature pump. We demonstrated the cell lysis of Pseudomonas putida as the target bacterium using the micro corona ionizer. At a flow rate of 38 ml/min and applied corona voltage of 2000 V, 98.5 ± 0.2% lysis (normalized to sonication result) was achieved after 10 min. In comparison, untreated and air-treated samples showed normalized % lysis of 11.9 ± 2.4 and 36.1 ± 1.7%, respectively. We also showed that the cell lysis efficiency could be significantly increased by increasing the flow rate and the applied corona voltage. By comparing the experimental results for continuous and pulsed treatment, we verified that the percentage of

Ionization detector

International Nuclear Information System (INIS)

Solomon, E.E.

1980-01-01

A safe and reliable apparatus for detecting products of combustion and aerosols in the atmosphere was developed which uses a beta source. It is easy to adjust for optimum performance. The ionization detector comprises a double chamber; one of the chambers is the basic sensing chamber. The sensing chamber is ported to both the secondary chambers to account for slow ambient changes in the atmosphere outside of the chamber. The voltages from the ionization chamber are adjusted with electrodes in each chamber. The ionization chamber contains baffles to direct the air to be sensed as well as an electrostatic screen. A unique electronic circuit provides an inexpensive and reliable means for detecting the signal change which occurs in the ionization chamber. The decision level of the alarm circuit can be adjusted to allow for any desired sensitivity. (D.N.)

NCI's Distributed Geospatial Data Server

Science.gov (United States)

Larraondo, P. R.; Evans, B. J. K.; Antony, J.

2016-12-01

Earth systems, environmental and geophysics datasets are an extremely valuable source of information about the state and evolution of the Earth. However, different disciplines and applications require this data to be post-processed in different ways before it can be used. For researchers experimenting with algorithms across large datasets or combining multiple data sets, the traditional approach to batch data processing and storing all the output for later analysis rapidly becomes unfeasible, and often requires additional work to publish for others to use. Recent developments on distributed computing using interactive access to significant cloud infrastructure opens the door for new ways of processing data on demand, hence alleviating the need for storage space for each individual copy of each product. The Australian National Computational Infrastructure (NCI) has developed a highly distributed geospatial data server which supports interactive processing of large geospatial data products, including satellite Earth Observation data and global model data, using flexible user-defined functions. This system dynamically and efficiently distributes the required computations among cloud nodes and thus provides a scalable analysis capability. In many cases this completely alleviates the need to preprocess and store the data as products. This system presents a standards-compliant interface, allowing ready accessibility for users of the data. Typical data wrangling problems such as handling different file formats and data types, or harmonising the coordinate projections or temporal and spatial resolutions, can now be handled automatically by this service. The geospatial data server exposes functionality for specifying how the data should be aggregated and transformed. The resulting products can be served using several standards such as the Open Geospatial Consortium's (OGC) Web Map Service (WMS) or Web Feature Service (WFS), Open Street Map tiles, or raw binary arrays under

Desorption electrospray ionization mass spectrometry in the analysis of chemical food contaminants in food

NARCIS (Netherlands)

Nielen, M.W.F.; Hooijerink, H.; Zomer, P.; Mol, J.G.J.

2011-01-01

Since its introduction, desorption electrospray ionization (DESI) mass spectrometry (MS) has been mainly applied in pharmaceutical and forensic analysis. We expect that DESI will find its way in many different fields, including food analysis. In this review, we summarize DESI developments aimed at

Effects of ionizing radiation in ginkgo and guarana

International Nuclear Information System (INIS)

Rabelo Soriani, Renata; Satomi, Lucilia Cristina; Pinto, Terezinha de Jesus A.

2005-01-01

Raw plant materials normally carry high bioburden due to their origin, offering potential hazards to consumers. The use of decontamination processes is therefore an important step towards the consumer safety and therapeutical efficiency. Several authors have reported the treatment of medicinal herbs with ionizing radiation. This work evaluated the effects of different radiation doses on the microbial burden and chemical constituents of ginkgo (Ginkgo biloba L.) and guarana (Paullinia cupana H.B.K.)

Degradation of chlorpyrifos by ionizing radiation

International Nuclear Information System (INIS)

Mori, M.N.; Oikawa, H.; Sampa, M.H.O.; Duarte, C.L.

2006-01-01

Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60 Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GCFID). (author)

Effect of bcl-2 antisense oligodexynucleotides on chemotherapy efficacy of Vp-16 on human small cell lung cancer cell line NCI-H69

International Nuclear Information System (INIS)

He Wenqian; Liu Zhonghua

2007-01-01

Objective: To study the effect of bcl-2 antisense oligodexynucleotides on chemotherapy efficacy of Vp-16 on human small cell lung cancer cell line NCI-H69. Methods: Cultured NCI-H69 cells were derided into 4 groups: bcl-2 antisense oligodexynucleotides (ASODN) added, sense oligodexynucleotides (SODN) added, nonsense oligodexynucleotides (NSODN) added and control (no nucleotides added), the oligodexynucleotides were transfected into the cultured cells with oligofectamine. The cellular expression of Bcl-2 protein 72h later was examined with Western-Blot. The four different groups of cultured tumor cells were treated with etopside(Vp-16) at different concentrations (0, 0.25, 0.5, 1.0, 2.0 and 4.0 μg/ml) for 48hr then the cell survival fraction was assessed with MTY test. Results: The apoptotic rate of cells in the ASODN group was significantly higher than that of the control group, also, the survival fraction of cells in ASODN group was significantly lower than that of the control group. The Bcl-2 protein expression in ASODN group was significantly lower than that in the control group, but no inhibition was observed in SODN and NSODN groups. Conclusion: The bcl-2 ASODN could enhance the sensitivity to chemotherapy with Vp-16 in small cell lung cancer cell line NCI-H69 by effectively blocking bcl-2 gene expression. (authors)

Resveratrol enhances radiosensitivity of human non-small cell lung cancer NCI-H838 cells accompanied by inhibition of nuclear factor-kappa B activation

International Nuclear Information System (INIS)

Liao, Hui-Fen; Kuo Cheng-Deng; Yang, Yuh-Cheng; Lin, Chin-Ping; Tai, Hung-Chi; Chen, Yu-Jen; Chen, Yu-Yawn

2005-01-01

Resveratrol, a polyphenol in red wine, possesses many pharmacological activities including cardio-protection, chemoprevention, anti-tumor effects, and nuclear factor-kappa B (NF-κB) inactivation. The present study was designed to evaluate the effects and possible mechanism of resveratrol in enhancing radiosensitivity of lung cancer cells. Human non-small cell lung cancer NCI-H838 cells were irradiated with or without resveratrol pretreatment. The surviving fraction and sensitizer enhancement ratio (SER) were estimated by using a colony formation assay and linear-quadratic model. The cell-cycle distribution was evaluated by using prospidium iodide staining and flow cytometry. An enzyme-linked immunosorbent assay (ELISA)-based assay with immobilized oligonucleotide was performed to assess the DNA binding activity of NF-κB. Resveratrol had no direct growth-inhibitory effect on NCI-H838 cells treated for 24 hours with doses up to 25 μM. Pretreatment with resveratrol significantly enhanced cell killing by radiation, with an SER up to 2.2. Radiation activated NF-κB, an effect reversed by resveratrol pretreatment. Resveratrol resulted in a decrease of cells in the G 0 /G 1 phase and an increase in the S phase. Our results demonstrate that resveratrol enhances the radiosensitivity of NCI-H838 cells accompanied by NF-κB inhibition and S-phase arrest. (author)

The equation of state and ionization equilibrium of dense aluminum plasma with conductivity verification

International Nuclear Information System (INIS)

Wang, Kun; Shi, Zongqian; Shi, Yuanjie; Bai, Jun; Wu, Jian; Jia, Shenli

2015-01-01

The equation of state, ionization equilibrium, and conductivity are the most important parameters for investigation of dense plasma. The equation of state is calculated with the non-ideal effects taken into consideration. The electron chemical potential and pressure, which are commonly used thermodynamic quantities, are calculated by the non-ideal free energy and compared with results of a semi-empirical equation of state based on Thomas-Fermi-Kirzhnits model. The lowering of ionization potential, which is a crucial factor in the calculation of non-ideal Saha equation, is settled according to the non-ideal free energy. The full coupled non-ideal Saha equation is applied to describe the ionization equilibrium of dense plasma. The conductivity calculated by the Lee-More-Desjarlais model combined with non-ideal Saha equation is compared with experimental data. It provides a possible approach to verify the accuracy of the equation of state and ionization equilibrium

Ionizing radiation in environment

International Nuclear Information System (INIS)

Jandl, J.; Petr, I.

1988-01-01

The basic terms are explained such as the atom, radioactivity, nuclear reaction, interaction of ionizing radiation with matter, etc. The basic dosimetric variables and units and properties of radionuclides and ionizing radiation are given. Natural and artificial sources of ionizing radiation are discussed with regard to the environment and the propagation and migration of radionuclides is described in the environment to man. The impact is explained of ionizing radiation on the cell and the somatic and genetic effects of radiation on man are outlined. Attention is devoted to protection against ionizing radiation and to radiation limits, also to the detection, dosimetry and monitoring of ionizing radiation in the environment. (M.D.). 92 figs., 40 tabs. 74 refs

Spectrophotometric observations of very low ionization HII regions in the LMC

International Nuclear Information System (INIS)

Pena, M.; Ruiz, M.T.; Rubio, M.

1987-01-01

Optical spectrophotometric observations of 17 very low ionization HII regions of the LMC are reported. Physical conditions and chemical composition of these objects are derived from the emission line intensities. The average chemical abundances obtained are: log O/H=8.49+-0.08, log N/H=6.91+-0.07 and log S/H=6.89+-0.10. We do not find evidence of any composition gradient in the LMC. The HII regions in the vicinity of the detected molecular cloud complexes show higher nebular reddening. (Author)

Photodegradation of secondary organic aerosol generated from limonene oxidation by ozone studied with chemical ionization mass spectrometry

Directory of Open Access Journals (Sweden)

X. Pan

2009-06-01

Full Text Available Photodegradation of secondary organic aerosol (SOA prepared by ozone-initiated oxidation of D-limonene is studied with an action spectroscopy approach, which relies on detection of volatile photoproducts with chemical ionization mass-spectrometry as a function of the UV irradiation wavelength. Efficient photodegradation is observed for a broad range of ozone (0.1–300 ppm and D-limonene (0.02–3 ppm concentrations used in the preparation of SOA. The observed photoproducts are dominated by oxygenated C1-C3 compounds such as methanol, formic acid, acetaldehyde, acetic acid, and acetone. The irradiation wavelength dependence of the combined yield of the photoproducts closely tracks the absorption spectrum of the SOA material suggesting that photodegradation is not limited to the UV wavelengths. Kinetic simulations suggest that RO₂+HO₂/RO₂ reactions represent the dominant route to photochemically active carbonyl and peroxide species in the limonene SOA prepared in these experiments. Similar photodegradation processes are likely to occur in realistic SOA produced by OH- or O₃-initiated oxidation of biogenic volatile organic compounds in clean air.

Computational Environments and Analysis methods available on the NCI High Performance Computing (HPC) and High Performance Data (HPD) Platform

Science.gov (United States)

Evans, B. J. K.; Foster, C.; Minchin, S. A.; Pugh, T.; Lewis, A.; Wyborn, L. A.; Evans, B. J.; Uhlherr, A.

2014-12-01

The National Computational Infrastructure (NCI) has established a powerful in-situ computational environment to enable both high performance computing and data-intensive science across a wide spectrum of national environmental data collections - in particular climate, observational data and geoscientific assets. This paper examines 1) the computational environments that supports the modelling and data processing pipelines, 2) the analysis environments and methods to support data analysis, and 3) the progress in addressing harmonisation of the underlying data collections for future transdisciplinary research that enable accurate climate projections. NCI makes available 10+ PB major data collections from both the government and research sectors based on six themes: 1) weather, climate, and earth system science model simulations, 2) marine and earth observations, 3) geosciences, 4) terrestrial ecosystems, 5) water and hydrology, and 6) astronomy, social and biosciences. Collectively they span the lithosphere, crust, biosphere, hydrosphere, troposphere, and stratosphere. The data is largely sourced from NCI's partners (which include the custodians of many of the national scientific records), major research communities, and collaborating overseas organisations. The data is accessible within an integrated HPC-HPD environment - a 1.2 PFlop supercomputer (Raijin), a HPC class 3000 core OpenStack cloud system and several highly connected large scale and high-bandwidth Lustre filesystems. This computational environment supports a catalogue of integrated reusable software and workflows from earth system and ecosystem modelling, weather research, satellite and other observed data processing and analysis. To enable transdisciplinary research on this scale, data needs to be harmonised so that researchers can readily apply techniques and software across the corpus of data available and not be constrained to work within artificial disciplinary boundaries. Future challenges will

Assessment of hydrogen bonding effect on ionization of water from ambient to supercritical region–MD simulation approach

International Nuclear Information System (INIS)

Swiatla-Wojcik, D.; Mozumder, A.

2014-01-01

We present a novel, molecular dynamics (MD) simulation based, strategy to analyze how the degree of hydrogen bonding may influence the ionization and dissociation of water upon heating from ambient to supercritical temperatures. Calculations show a negligible change in the ionization energy up to 200 °C. At higher temperatures the ionization energy increases due to the decreasing degree of hydrogen bonding. The influence of density (pressure) is pronounced in the supercritical region. The ionization is more energy consuming in the less dense fluid. We also show that high temperature and low density may promote dissociation of the electronically excited water molecules. Implications on the initial radiation chemical yields of the hydrated electron, hydrogen atom and hydroxyl radical are discussed. - Highlights: • Up to 200 °C changes in the vertical and adiabatic ionization potentials are negligible. • At higher temperatures ionization is more energy consuming. • Ionization potential increases with decreasing density of supercritical water. • High temperature and low density promote dissociation of the excited molecules

Shotgun lipidomic analysis of chemically sulfated sterols compromises analytical sensitivity

DEFF Research Database (Denmark)

Casanovas, Albert; Hannibal-Bach, Hans Kristian; Jensen, Ole Nørregaard

2014-01-01

Shotgun lipidomics affords comprehensive and quantitative analysis of lipid species in cells and tissues at high-throughput [1 5]. The methodology is based on direct infusion of lipid extracts by electrospray ionization (ESI) combined with tandem mass spectrometry (MS/MS) and/or high resolution F...... low ionization efficiency in ESI [7]. For this reason, chemical derivatization procedures including acetylation [8] or sulfation [9] are commonly implemented to facilitate ionization, detection and quantification of sterols for global lipidome analysis [1-3, 10]....

Barium ionization mechanisms in the CRRES G-1 and G-11b releases

International Nuclear Information System (INIS)

Hunton, D.E.

1993-01-01

The G-11b chemical release experiment form the Combined Release and Radiation Effects Satellite (CRRES) was conducted in darkness below the solar UV terminator to test the Critical Ionization Velocity (CIV) hypothesis. The Quadrupole Ion Mass Spectrometer (QIMS) aboard CRRES measured fluxes of barium ions from this darkness release that were only a factor of ten smaller than the G-1 release measurements in full sunlight. Possible mechanisms for this significant barium ionization in darkness include CIV, charge exchange with O + , collisional ionization and associative ionization. The authors have evaluated the relative contributions of the collisional mechanisms by constructing a simple model of barium ions from the darkness release seem to be consistent with recent measurements of the charge transfer cross section. A collective plasma ionization mechanism such as CIV does not seem to necessary in order to explain the large barium ion fluxes observed. However, QIMS could only detect barium ions formed several seconds after the initial detonation of the release canister. A CIV process could still have occurred very early in the expansion of the barium neutral cloud and the mass spectrometer would not have detected these ions

Method for the elucidation of the elemental composition of low molecular mass chemicals using exact masses of product ions and neutral losses: application to environmental chemicals measured by liquid chromatography with hybrid quadrupole/time-of-flight mass spectrometry.

Science.gov (United States)

Suzuki, Shigeru; Ishii, Tetsuko; Yasuhara, Akio; Sakai, Shinichi

2005-01-01

A method for elucidating the elemental compositions of low molecular weight chemicals, based primarily on mass measurements made using liquid chromatography (LC) with time-of-flight mass spectrometry (TOFMS) and quadrupole/time-of-flight mass spectrometry (LC/QTOFMS), was developed and tested for 113 chemicals of environmental interest with molecular masses up to approximately 400 Da. As the algorithm incorporating the method is not affected by differences in the instrument used, or by the ionization method and other ionization conditions, the method is useful not only for LC/TOFMS, but also for all kinds of mass spectra measured with higher accuracy and precision (uncertainties of a few mDa) employing all ionization methods and on-line separation techniques. The method involves calculating candidate compositions for intact ionized molecules (ionized forms of the sample molecule that have lost or gained no more than a proton, i.e., [M+H](+) or [M-H](-)) as well as for fragment ions and corresponding neutral losses, and eliminating those atomic compositions for the molecules that are inconsistent with the corresponding candidate compositions of fragment ions and neutral losses. Candidate compositions were calculated for the measured masses of the intact ionized molecules and of the fragment ions and corresponding neutral losses, using mass uncertainties of 2 and 5 mDa, respectively. Compositions proposed for the ionized molecule that did not correspond to the sum of the compositions of a candidate fragment ion and its corresponding neutral loss were discarded. One, 2-5, 6-10, 11-20, and >20 candidate compositions were found for 65%, 39%, 1%, 1%, and 0%, respectively, for the 124 ionized molecules formed from the 113 chemicals tested (both positive and negative ions were obtained from 11 of the chemicals). However, no candidate composition was found for 2% of the test cases (i.e., 3 chemicals), for each of which the measured mass of one of the product ions was in

Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

International Nuclear Information System (INIS)

Stoyanov, D G

2007-01-01

The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained

Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

Energy Technology Data Exchange (ETDEWEB)

Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

2007-08-15

The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

International Nuclear Information System (INIS)

Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J.

2015-01-01

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a “soft” ion source for preserving highly diagnostic molecular ion is desirable, as compared to the “hard” ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. - Highlights: • Atmospheric pressure ion sources (APCI, ESI, APPI, APLC etc) enable the coupling of LC-based high-end MS to GC. • APIs show advantages in selectivity and sensitivity compared with EI in GC-MS. • Accurate mass database in GC-APCI/MS is emerging as an alternative to GC-EI/MS database.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

Energy Technology Data Exchange (ETDEWEB)

Li, Du-Xin; Gan, Lin; Bronja, Amela [University of Duisburg-Essen, Applied Analytical Chemistry, Universitaetsstr. 5-7, 45141 Essen (Germany); Schmitz, Oliver J., E-mail: oliver.schmitz@uni-due.de [University of Duisburg-Essen, Applied Analytical Chemistry, Universitaetsstr. 5-7, 45141 Essen (Germany)

2015-09-03

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a “soft” ion source for preserving highly diagnostic molecular ion is desirable, as compared to the “hard” ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. - Highlights: • Atmospheric pressure ion sources (APCI, ESI, APPI, APLC etc) enable the coupling of LC-based high-end MS to GC. • APIs show advantages in selectivity and sensitivity compared with EI in GC-MS. • Accurate mass database in GC-APCI/MS is emerging as an alternative to GC-EI/MS database.

Indexing molecules with chemical graph identifiers.

Science.gov (United States)

Gregori-Puigjané, Elisabet; Garriga-Sust, Rut; Mestres, Jordi

2011-09-01

Fast and robust algorithms for indexing molecules have been historically considered strategic tools for the management and storage of large chemical libraries. This work introduces a modified and further extended version of the molecular equivalence number naming adaptation of the Morgan algorithm (J Chem Inf Comput Sci 2001, 41, 181-185) for the generation of a chemical graph identifier (CGI). This new version corrects for the collisions recognized in the original adaptation and includes the ability to deal with graph canonicalization, ensembles (salts), and isomerism (tautomerism, regioisomerism, optical isomerism, and geometrical isomerism) in a flexible manner. Validation of the current CGI implementation was performed on the open NCI database and the drug-like subset of the ZINC database containing 260,071 and 5,348,089 structures, respectively. The results were compared with those obtained with some of the most widely used indexing codes, such as the CACTVS hash code and the new InChIKey. The analyses emphasize the fact that compound management activities, like duplicate analysis of chemical libraries, are sensitive to the exact definition of compound uniqueness and thus still depend, to a minor extent, on the type and flexibility of the molecular index being used. Copyright © 2011 Wiley Periodicals, Inc.

Pulsed plasma sources for the production of intense ion beams based on catalytic resonance ionization

International Nuclear Information System (INIS)

Knyazev, B.A.; Mel'nikov, P.I.; Bluhm, H.

1994-01-01

In this paper we describe a technique to produce planar and volumetric ion sources of nearly every element. This technique is based on a generalization of the LIBORS-process (Laser Ionization Based On Resonant Saturation) which because of its similarity to chemical catalytic reactions has been called CATRION (CATalytic Resonance IONization). A vapor containing the desired atomic species is doped with a suitable element processing resonance transitions that can be pumped ro saturation with a laser. By superelastic collisions with the excited atoms and by simulated bremsstrahlung absorption seed electrons are heated. It is the heated electron component which then by collisional processes ionizes the desired atomic species and are multiplied. 41 refs.; 4 figs.; 3 tabs

Atmospheric fate of non volatile and ionizable compounds

DEFF Research Database (Denmark)

Franco, Antonio; Hauschild, Michael Zwicky; Jolliet, Olivier

2011-01-01

, and the parameters describing air–water partitioning (KAW and temperature) and ionization (pKa and pH) are the key parameters determining the potential for long range transport. Wet deposition is an important removal process, but its efficiency is limited, primarily by the duration of the dry period between...... simulations describing the uncertainty of substance and environmental input properties were run to evaluate the impact of atmospheric parameters, ionization and air–water (or air–ice) interface enrichment. The rate of degradation and the concentration of OH radicals, the duration of dry and wet periods...... precipitation events. Given the underlying model assumptions, the presence of clouds contributes to the higher persistence in the troposphere because of the capacity of cloud water to accumulate and transport non-volatile (e.g.2,4-D) and surface-active chemicals (e.g. PFOA). This limits the efficiency of wet...

Ionization in liquids

International Nuclear Information System (INIS)

Bakale, G.

1990-01-01

During the 1987--1990 reporting period, studies were conducted that entailed the direct measurement of the transport and reaction properties of excess electrons in nonpolar liquids through the use of pulse-conductivity techniques. The results obtained from these studies should be applicable toward the development of a better understanding of the primary ionizing event in liquids as well as to providing physico-chemical information that is pertinent to electron-transfer processes that are ubiquitous in biological systems. Progress was also made in developing a better understanding of electron attachment reactions in liquids through measurements of the electron attachment rate constants, k e s, of a variety of electron-attaching solutes. The effects of several functional groups substituted at different positions on benzene were studied in liquid cyclohexane and isooctane. The electron-attaching properties of chemicals having well characterized carcinogenic properties were studied in cyclohexane to determine if the measure of electron-accepting potential that k e provides can elucidate the role that electrons play in the initiation step of carcinogenesis. The k e s that were measured indicate that the k e -carcinogenicity correlation that was observed can be used to complement short-term carcinogen-screening bioassays to identify potential carcinogens. 115 refs., 6 tabs

Auger electron spectroscopy, ionization loss spectroscopy, appearance potential spectroscopy

International Nuclear Information System (INIS)

Riwan, R.

1973-01-01

The spectroscopy of surfaces using an incident electron beam is studied. The fundamental mechanisms are discussed together with the parameters involved in Auger emission: excitation of the atom, de-excitation by electron emission, and the migration of electrons towards the surface and their ejection. Some examples of applications are given (surface structures, metallurgy, chemical information). Two new techniques for analyzing surfaces are studied: ionization spectroscopy, and appearance potential spectroscopy [fr

Resonance ionization detection of combustion radicals

Energy Technology Data Exchange (ETDEWEB)

Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

1993-12-01

Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

Avaluació de competències professionalitzadores en els estudis de grau de comunicació audiovisual

Directory of Open Access Journals (Sweden)

Marina Romeo

2017-01-01

Full Text Available Els recents canvis en la formació universitària han comportat un destacable nivell de professionalització dels estudis i una constant adequació a les demandes socials. En aquest sentit, una de les necessitats per a la formació universitària a l'àrea de la comunicació audiovisual és desenvolupar en els estudiants competències professionalitzadores que els permetin trobar nínxols d'ocupació en un mercat altament competitiu i sotmès a canvis continus. Aquesta recerca té per objecte crear una rúbrica que permeti avaluar l'aprenentatge professionalitzador en els estudis de grau en comunicació audiovisual (CAV que es desenvolupen a Espanya. Per desenvolupar-la hem comptat amb ocupadors i acadèmics experts de l'àmbit de la comunicació audiovisual triats de forma intencional. La rúbrica final desenvolupada, a més de permetre avaluar el grau d'adquisició de les competències professionalitzadores en CAV, permet dibuixar un mapa clar de l'organització i adequació dels processos i metodologies docents. En aquest sentit, la rúbrica pot ser un instrument pedagògic clau per a una futura promoció d'estudiants, i es pot convertir en un instrument que afavoreixi l'avaluació formativa dels alumnes.

Proof of cannabis administration by sensitive detection of 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid in hair using selective methylation and application of liquid chromatography- tandem and multistage mass spectrometry.

Science.gov (United States)

Thieme, Detlef; Sachs, Hans; Uhl, Michael

2014-01-01

The identification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in hair represents an exceptional forensic analytical challenge due to low target concentrations in a complex matrix. Several dedicated techniques [gas chromatography-negative chemical ionization-tandem mass spectrometry (GC-NCI-MS/MS) or GC-GC-MS couplings] were specifically introduced into forensic toxicology aiming to a selective and sensitive identification of THCCOOH in hair. The combination of liquid-chromatography (LC) and MS/MS gained an outstanding relevance in forensic toxicology (including the detection of cannabinoids). However, its application to hair matrix is characterized by a lack of specificity which is due to the unspecific decarboxylation as most abundant fragmentation reaction. Therefore, various chemical modifications of the carboxyl and/or phenolic hydroxyl groups were examined to improve the selectivity. The selective methylation of the 9-carboxyl-group proved to be the most efficient derivatization procedure. Hair extracts were redissolved in acetonitrile and after addition of few milligrams of solid sodium carbonate derivatized with 25 μL methyl iodide. The resulting THC-9-carboxymethylester was separated by conventional reverse phase LC and selectively detected using negative electrospray ionization by recording the fragmentation reactions 357➔325 and 357➔297. Resulting limits of quantification were below 100 fg/mg. A further significant improvement was achieved by application of the multistage MS3 fragmentation 357➔325➔297. To verify the validity of this procedure, a systematic quantitative comparison of THCCOOH concentrations in hair with data from a well established GC-NCI-MS/MS technique was performed. Both techniques proved to be in good accordance (R(2)=0.647, p = <0.001) and equally suitable for hair testing of THCCOOH. Copyright © 2013 John Wiley & Sons, Ltd.

Single-photon double and triple ionization of acetaldehyde (ethanal) studied by multi-electron coincidence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zagorodskikh, S. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Zhaunerchyk, V. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Mucke, M. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Eland, J.H.D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Squibb, R.J. [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Karlsson, L. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, P. [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Feifel, R., E-mail: raimund.feifel@gu.se [Department of Physics, University of Gothenburg, Origovägen 6B, SE-412 96 Gothenburg (Sweden); Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

2015-12-16

Highlights: • The first ever valence double ionization spectrum of acetaldehyde is reported. • The first ever site-selectively extracted Auger spectra of acetaldehyde are reported. • The first ever Auger spectra of acetaldehyde involving shake-up states are reported. • The first ever triple ionization spectra of acetaldehyde are reported. • The first ever energy sharing of electron pairs emitted by acetaldehyde is presented. - Abstract: Single-photon multiple ionization processes of acetaldehyde (ethanal) have been experimentally investigated by utilizing a multi-particle coincidence technique based on the time-of-flight magnetic bottle principle, in combination with either a synchrotron radiation source or a pulsed helium discharge lamp. The processes investigated include double and triple ionization in the valence region as well as single and double Auger decay of core-ionized acetaldehyde. The latter are studied site-selectively for chemically different carbon core vacancies, scrutinizing early theoretical predictions specifically made for the case of acetaldehyde. Moreover, Auger processes in shake-up and core-valence ionized states are investigated. In the cases where the processes involve simultaneous emission of two electrons, the distributions of the energy sharing are presented, emphasizing either the knock-out or shake-off mechanism.

75 FR 70010 - Government-Owned Inventions; Availability for Licensing

Science.gov (United States)

2010-11-16

... Appella (NCI), John K. Inman (NIAID), Deyun Wang (NIDDK), Lisa M. Miller Jenkins (NCI), Ryo Hayashi (NCI). Publications: 1. Miller Jenkins LM, et al. Nature Chemical Biology, in press. 2. Miller Jenkins LM, et al..., evaluate, or commercialize this invention. Please contact Dr. Henry Eden at [email protected] for more...

Silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging.

Science.gov (United States)

Sekuła, Justyna; Nizioł, Joanna; Rode, Wojciech; Ruman, Tomasz

2015-09-21

Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. This review provides an overview of the literature on silver nanomaterials as non-conventional desorption and ionization promoters in LDI-MS and mass spectrometry imaging.

Long-term biological effects induced by ionizing radiation--implications for dose mediated risk.

Science.gov (United States)

Miron, S D; Astărăstoae, V

2014-01-01

Ionizing radiations are considered to be risk agents that are responsible for the effects on interaction with living matter. The occurring biological effects are due to various factors such as: dose, type of radiation, exposure time, type of biological tissue, health condition and the age of the person exposed. The mechanisms involved in the direct modifications of nuclear DNA and mitochondrial DNA are reviewed. Classical target theory of energy deposition in the nucleus that causes DNA damages, in particular DNA double-strand breaks and that explanation of the biological consequences of ionizing radiation exposure is a paradigm in radiobiology. Recent experimental evidences have demonstrated the existence of a molecular mechanism that explains the non-targeted effects of ionizing radiation exposure. Among these novel data, genomic instability and a variety of bystander effects are discussed here. Those bystander effects of ionizing radiation are fulfilled by cellular communication systems that give rise to non-targeted effects in the neighboring non irradiated cells. This paper provides also a commentary on the synergistic effects induced by the co-exposures to ionizing radiation and various physical agents such as electromagnetic fields and the co-exposures to ionizing radiation and chemical environmental contaminants such as metals. The biological effects of multiple stressors on genomic instability and bystander effects are also discussed. Moreover, a brief presentation of the methods used to characterize cyto- and genotoxic damages is offered.

NCI Releases Video: Proteogenomics Research - On the Frontier of Precision Medicine | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

The Clinical Proteomic Tumor Analysis Consortium (CPTAC) of the National Cancer Institute (NCI), part of the National Institutes of Health, announces the release of an educational video titled “Proteogenomics Research: On the Frontier of Precision Medicine."  Launched at the HUPO2017 Global Leadership Gala Dinner, catalyzed in part by the Cancer Moonshot initiative and featuring as keynote speaker the 47th Vice President of the United States of America Joseph R.

Effect of ionizing radiation in the quality of exportable asparagus

International Nuclear Information System (INIS)

Rubio C, T.; Espinoza B, J.; Godoy, A.M.

1989-01-01

Due to the severe restriction which has been set upon the use of chemical fumigant by the importing countries of our horticulture products it has been studied the use of ionizing radiation in asparagus as an alternative treatment for quarantine restriction. The used are 0,15; 0,5; 1.0 y 2.0 kGy. Argenteuil and UC-157 varieties were used. The harvest, handing and storage conditions were the same as the ones export companies use. Both varieties were studied by the following quality parameters: pH, acidity, moisture, soluble solids, vitamin C, fibre content, dissecation, seeding and spreading, shooting, spear lengh, weight loss, microbial and moulds contamination, cutting resistance, respiratory rate, color and sensorial evaluation. From the result obtained it is possible to conclude that the irradiation did not produce deleterous effects on chemical, microbiological or organoleptic parameters in both varieties. From the point of view of the market quality the ionizing radiation could be used as a quarantine treatment under the normal marketing conditions used in Chile. Dose of 2.0 kGy does not produce a shelf life extention. (author)

High-throughput trace analysis of explosives in water by laser diode thermal desorption/atmospheric pressure chemical ionization-tandem mass spectrometry.

Science.gov (United States)

Badjagbo, Koffi; Sauvé, Sébastien

2012-07-03

Harmful explosives can accumulate in natural waters in the long term during their testing, usage, storage, and dumping and can pose a health risk to humans and the environment. For the first time, attachment of small anions to neutral molecules in laser diode thermal desorption/atmospheric pressure chemical ionization was systematically investigated for the direct determination of trace nitroaromatics, nitrate esters, and nitramine explosives in water. Using ammonium chloride as an additive improved the instrument response for all the explosives tested and promoted the formation of several characteristic adduct ions. The method performs well achieving good linearity over at least 2 orders of magnitude, with coefficients of determination greater than 0.995. The resulting limits of detection are in the range of 0.009-0.092 μg/L. River water samples were successfully analyzed by the proposed method with accuracy in the range of 96-98% and a response time of 15 s, without any further pretreatment or chromatographic separation.

'Saddle-point' ionization

International Nuclear Information System (INIS)

Gay, T.J.; Hale, E.B.; Irby, V.D.; Olson, R.E.; Missouri Univ., Rolla; Berry, H.G.

1988-01-01

We have studied the ionization of rare gases by protons at intermediate energies, i.e., energies at which the velocities of the proton and the target-gas valence electrons are comparable. A significant channel for electron production in the forward direction is shown to be 'saddle-point' ionization, in which electrons are stranded on or near the saddle-point of electric potential between the receding projectile and the ionized target. Such electrons yield characteristic energy spectra, and contribute significantly to forward-electron-production cross sections. Classical trajectory Monte Carlo calculations are found to provide qualitative agreement with our measurements and the earlier measurements of Rudd and coworkers, and reproduce, in detail, the features of the general ionization spectra. (orig.)

Heating and ionization in MHD shock waves propagating into partially ionized plasma

International Nuclear Information System (INIS)

Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

1975-09-01

A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

Heating and ionization in MHD shock wave propagating into partially ionized plasma

International Nuclear Information System (INIS)

Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

1975-09-01

A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

Five-photon ionization of atomic hydrogen at wavelengths around the threshold for four-photon ionization

International Nuclear Information System (INIS)

Gontier, Y.; Trahin, M.; Wolff-Rottke, B.; Rottke, H.; Welge, K.H.; Feldmann, D.

1992-01-01

Theoretical and experimental studies show the strong influence of the three-photon nearly resonant 2p state on four- and five-photon ionization of atomic hydrogen near the threshold for four-photon ionization. Changes in five-photon ionization occur when the four-photon ionization channel opens. The angular distributions of photoelectrons from five-photon ionization of H are studied at five wavelengths which cover the range from four-photon resonance with high-lying Rydberg states (n≥10) to direct four-photon ionization into the continuum. The role of resonances in this ionization process is discussed. A fair agreement is found in comparing experimental and theoretical results

Equipment for handling ionization chamber

International Nuclear Information System (INIS)

Altmann, J.

1988-01-01

The device consists of an ionization channel with an ionization chamber, of a support ring, axial and radial bearings, a sleeve, a screw gear and an electric motor. The ionization chamber is freely placed on the bottom of the ionization channel. The bottom part of the channel deviates from the vertical axis. The support ring propped against the axial bearing in the sleeve is firmly fixed to the top part of the ionization channel. The sleeve is fixed to the reactor lid. Its bottom part is provided with a recess for the radial bearing which is propped against a screw wheel firmly connected to the ionization channel. In measuring neutron flux, the screw wheel is rotated by the motor, thus rotating the whole ionization channel such that the ionization chamber is displaced into the reactor core.(J.B.). 1 fig

Foodstuffs preservation by ionization

International Nuclear Information System (INIS)

1991-12-01

This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)

Incorporació de petites seqüències de cinema comercial en l’ensenyament de les drogodependències. Assaig pilot en l'assignatura de Toxicologia

Directory of Open Access Journals (Sweden)

Miguel Rodamilans-Pérez

2013-01-01

Full Text Available El Grup d'Innovació Docent Orfila, en el seu projecte per millorar la qualitat de la docència, està assajant la utilització del cinema amb finalitat didàctica. El material didàctic que hem desenvolupat en aquest projecte són petites seqüències de pel·lícules comercials de 3 a 5 minuts, per ser utilitzades com a elements il·lustratius del procés addictiu. Se seleccionen escenes de la filmografia i s'adeqüen als nostres programes docents. Es recull l'opinió dels professors participants, així com la dels alumnes, mitjançant una entrevista personal i una enquesta d'opinió, respectivament.De les entrevistes als professors i de les enquestes d'opinió dels alumnes, es dedueix un alt grau de satisfacció.

Ionizing radiation biological effects and the proper protective measures against it's harmful effects

International Nuclear Information System (INIS)

Hhalel, A.M.

1990-01-01

This book intrduces a good knowledge in specifications of ionizing radiation biological effects and the proper protective measures againest harmful effectes. The book is devided in to five main sections, the first one introduces the hostorical bachground of the contributions of a number of scietists in the basic knolwledge of radiation and its biological effects. The second section deals with the physical and chemical principles of radiation the third one talks about radiation detection. While the fourth section talks (via seven chapter) about the effectes of ionizing radiation on living organisms molecules cells, tissues organs systems and the living organism the fifth section talks about the uses of radiation sources, the probability of radiation accidents, protective measures, international recommendations related to doses and safe use of ionizing radiation. (Abed Al-wali Al-ajlouni). 53 refs., 107 figs., 13 tabs

Extrapolating ecological risks of ionizing radiation from individuals to populations to ecosystems

International Nuclear Information System (INIS)

Barnthouse, L.W.

1997-01-01

Approaches for protecting ecosystems from ionizing radiation are quite different from those used for protecting ecosystems from adverse effects of toxic chemicals. The methods used for chemicals are conceptually similar to those used to assess risks of chemicals to human health in that they focus on the protection of the most sensitive or most highly exposed individuals. The assumption is that if sensitive or maximally exposed species and life stages are protected, then ecosystems will be protected. Radiological protection standards, on the other hand, are explicitly premised on the assumption that organisms, populations and ecosystems all possess compensatory capabilities to allow them to survive in the face of unpredictable natural variation in their environments. These capabilities are assumed to persist in the face of at least some exposure to ionizing radiation. The prevailing approach to radiological protection was developed more than 30 years ago, at a time when the terms risk assessment and risk management were rarely used. The expert review approach used to derive radiological protection standards is widely perceived to be inconsistent with the open, participatory approach that prevails today for the regulation of toxic chemicals. The available data for environmental radionuclides vastly exceeds that available for any chemical. Therefore, given an understanding of dose-response relationships for radiation effects and exposures for individual organisms, it should be possible to develop methods for quantifying effects of radiation on populations. A tiered assessment scheme as well as available population models that could be used for the ecological risk assessment of radionuclides is presented. (author)

Ionization of food products

International Nuclear Information System (INIS)

Vasseur, J.P.

1991-01-01

After general remarks on foods preservation, on international works and on ionization future prospects, main irradiation sources are described. Recalls on radioactivity, on radiation-matter interaction, on toxicology of ionized foods and on ionized foods detection are given. Ionization applications to various products are reviewed, especially in: - Poultry meat - Fishing products - Fresh fruits and vegetables - Dry fruits and vegetables - spices, tea, infusion - prepacked products... An evaluation of economics and sociocultural impacts is presented in connection with recent experiments [fr

Chemical characterisation of non-defective and defective green arabica and robusta coffees by electrospray ionization-mass spectrometry (ESI-MS).

Science.gov (United States)

Mendonça, Juliana C F; Franca, Adriana S; Oliveira, Leandro S; Nunes, Marcella

2008-11-15

The coffee roasted in Brazil is considered to be of low quality, due to the presence of defective coffee beans that depreciate the beverage quality. These beans, although being separated from the non-defective ones prior to roasting, are still commercialized in the coffee trading market. Thus, it was the aim of this work to verify the feasibility of employing ESI-MS to identify chemical characteristics that will allow the discrimination of Arabica and Robusta species and also of defective and non-defective coffees. Aqueous extracts of green (raw) defective and non-defective coffee beans were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS) and this technique provided characteristic fingerprinting mass spectra that not only allowed for discrimination of species but also between defective and non-defective coffee beans. ESI-MS profiles in the positive mode (ESI(+)-MS) provided separation between defective and non-defective coffees within a given species, whereas ESI-MS profiles in the negative mode (ESI(-)-MS) provided separation between Arabica and Robusta coffees. Copyright © 2008 Elsevier Ltd. All rights reserved.

Characterisation and comparison of the uptake of ionizable and polar pesticides, pharmaceuticals and personal care products by POCIS and Chemcatchers

NARCIS (Netherlands)

Kaserzon, S.L.; Hawker, D.W.; Kennedy, K.; Bartkow, M.; Carter, S.; Booij, K.; Mueller, J.F.

2014-01-01

Growing concern about the environmental impact of ionizable and polar organic chemicals such as pesticides, pharmaceuticals and personal care products has lead to the inclusion of some in legislative and regulatory frameworks. It is expected that future monitoring requirements for these chemicals in

Ionizing radiations

International Nuclear Information System (INIS)

Anon.

1999-01-01

This is an update about the radiological monitoring in base nuclear installations. A departmental order of the 23. march 1999 (J.O.28. april, p.6309) determines the enabling rules by the Office of Protection against Ionizing Radiations of person having at one's disposal the results with names of individual exposure of workers put through ionizing radiations. (N.C.)

Study about the use of ionizing radiation to delay the putrefaction of strawberries 'Tioga'

International Nuclear Information System (INIS)

Ritacco, M.

1988-01-01

The influence of the ionizing radiation has been studied in fresh strawberries of the variety 'Tioga', with the purpose to extend its commercialization period. After the packaging in semi-permeable polyethylene, the material was procesed using 60 Co source of 400kCi. The strawberries were irradiated with a dose of 2kGy. The treated products and the unirradiated ones were stored refrigerated at 5 deg C with a relative humidity of 90 % and in absence of light. Each 4 days, chemical, organoleptics and microbiological studies were carried out and conditions of expense and transport post-irradiation were simulated. The results obtained would indicate the technological viability of ionizing radiations on this type of berries, keeping them in a good state during a period of 28 days post-treatment, the unirradiated material showed undiserable microbiological, organoleptics and chemical alterations after the 4th day of storage. (Autor) [es

Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

Science.gov (United States)

Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

2015-06-02

A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization

International Nuclear Information System (INIS)

Kern, P.

1995-01-01

This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it's also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs

Chemical Insights from Carbon 1s Photoelectron Spectroscopy and Theoretical Modeling

International Nuclear Information System (INIS)

Oltedal, Velaug M

2007-05-01

Inner-shell ionization energies provide local probes of the charge distribution in molecules and of the ability of a molecule to accept charge at specific sites. As such, core-ionization energies are related to and may provide insight into other chemical properties that depend on the same ability. X-ray photoelectron spectroscopy (XPS) is the preferred tool for exploring core-ionization energies. In the present work, synchrotron radiation was used to acquire photoelectron spectra of several carbon-containing molecules in the gas phase. Carbon 1s ionization energies are of special interest because of the vital role of organic molecules in life processes. A prerequisite for obtaining accurate ionization energies is access to reliable methods for calibration of the energies. This work has been concerned with establishing procedures for very accurate calibration of C1s ionization energies

Resonance ionization laser ion sources for on-line isotope separators (invited)

International Nuclear Information System (INIS)

Marsh, B. A.

2014-01-01

A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented

Which Molecular Features Affect the Intrinsic Hepatic Clearance Rate of Ionizable Organic Chemicals in Fish?

NARCIS (Netherlands)

Chen, Yi; Hermens, Joop L M; Jonker, Michiel T O; Arnot, Jon A; Armitage, James M; Brown, Trevor; Nichols, John W; Fay, Kellie A; Droge, Steven T J

2016-01-01

Greater knowledge of biotransformation rates for ionizable organic compounds (IOCs) in fish is required to properly assess the bioaccumulation potential of many environmentally relevant contaminants. In this study, we measured in vitro hepatic clearance rates for 50 IOCs using a pooled batch of

Studies on radiation-induced chromosome damage in humans: Semi-annual progress report, October 1, 1986-March 31, 1987

International Nuclear Information System (INIS)

Littlefield, L.G.

1987-01-01

This report summarizes recent research to determine and report the frequency of somatic cell chromosome aberrations in approximately 200 lymphocyte metaphases from each of 200 control patients or persons who received radiation for enlarged thymus, and from an additional 475 irradiated and control subjects selected by NCI from populations exposed to therapeutic ionizing radiation during the period 1930 to 1970. The priority of populations to be studied will be determined by NCI in consultation with the contractor and with advice from NCI consultants. Additional research will determine and report dose response curves among the several populations, to determine how differences with respect to radiation dose, quality of radiation, fractionation, sex and age within and among groups affect the ''dose-response relationship.'' 7 tabs

Les experiències artístiques en l'espai públic. Art efímer com a catàlisi de la vida urbana

Directory of Open Access Journals (Sweden)

Lucila Urda Peña

2016-06-01

Full Text Available L'art efímer urbà, com a corrent d'expressió de pensament col·lectiu és una font de generació de projectes comunitaris en què els ciutadans poden recuperar "l'experiència de ciutat". La profusió de diverses manifestacions d'art efímer en ciutats de tot el món des de començaments del segle XXI està tenint conseqüències en l'espai urbà tant a nivell local com a nivell global. Una d'elles és la transformació del paisatge urbà, cada vegada més considerat com a escenari visible en projectes de regeneració urbana. A més de la transformació física també es produeixen canvis en les dinàmiques urbanes ja que els efectes de les intervencions tenen conseqüències més enllà dels canvis d'imatge. Els efectes socioeconòmics locals o fins i tot globals de les transformacions lligades a l'art efímer són cada vegada més evidents. Aquest article relata l'origen i desenvolupament de diverses manifestacions artístiques urbanes i reflexiona sobre les seves conseqüències en la vida urbana com a eina de transformació física i social.

Biological effects of low-level ionizing and non-ionizing radiation

International Nuclear Information System (INIS)

Upton, A.C.

1986-01-01

Early in this century it was recognized that large doses of ionizing radiation could injure almost any tissue in the body, but small doses were generally thought to be harmless. By the middle of the century however it came to be suspected that even the smallest doses of ionizing radiation to the gonads might increase the risk of hereditary disease in subsequently-conceived offspring. Since then the hypothesis that carcinogenic and teratogenic effects also have no threshold has been adopted for purposes of radiological protection. It is estimated nevertheless that the risks that may be associated with natural background levels of ionizing irradiation are too small to be detectable. Hence validation of such risk estimates will depend on further elucidation of the dose-effect relationships and mechanisms of the effects in question, through studies at higher dose levels. In contrast to the situation with ionizing radiation, exposure to natural background levels of ultraviolet radiation has been implicated definitively in the etiology of skin cancers in fair-skinned individuals. Persons with inherited effects in DNA repair capacity are particularly susceptible. Non-ionizing radiations of other types can also affect health at high dose levels, but whether they can cause injury at low levels of exposure is not known

Improving clinical research and cancer care delivery in community settings: evaluating the NCI community cancer centers program.

Science.gov (United States)

Clauser, Steven B; Johnson, Maureen R; O'Brien, Donna M; Beveridge, Joy M; Fennell, Mary L; Kaluzny, Arnold D

2009-09-26

In this article, we describe the National Cancer Institute (NCI) Community Cancer Centers Program (NCCCP) pilot and the evaluation designed to assess its role, function, and relevance to the NCI's research mission. In doing so, we describe the evolution of and rationale for the NCCCP concept, participating sites' characteristics, its multi-faceted aims to enhance clinical research and quality of care in community settings, and the role of strategic partnerships, both within and outside of the NCCCP network, in achieving program objectives. The evaluation of the NCCCP is conceptualized as a mixed method multi-layered assessment of organizational innovation and performance which includes mapping the evolution of site development as a means of understanding the inter- and intra-organizational change in the pilot, and the application of specific evaluation metrics for assessing the implementation, operations, and performance of the NCCCP pilot. The assessment of the cost of the pilot as an additional means of informing the longer-term feasibility and sustainability of the program is also discussed. The NCCCP is a major systems-level set of organizational innovations to enhance clinical research and care delivery in diverse communities across the United States. Assessment of the extent to which the program achieves its aims will depend on a full understanding of how individual, organizational, and environmental factors align (or fail to align) to achieve these improvements, and at what cost.

Quantification of Biodegradation: Applied Example on Oil Seeps in Armàncies Fm, Southeastern Pyrenees

OpenAIRE

Permanyer, Albert; Caja, Miguel Ángel

2005-01-01

La presencia de petróleo expulsado directamente de la roca madre de la Formación Armàncies, constituye un caso único para el estudio de los procesos de biodegradación aeróbica en petróleo. El estado de degradación bacteriana es moderado y está principalmente limitado a la alteración de n-alcanos, isoprenoides y algunos aromáticos. La cuantificación ha sido realizada mediante el contenido en sulfuro y con los marcadores moleculares de la fracción aromática. Los resultados obtenidos...

Simultaneous atomization and ionization of large organic molecules using femtosecond laser ablation

International Nuclear Information System (INIS)

Kurata-Nishimura, Mizuki; Tokanai, Fuyuki; Matsuo, Yukari; Kobayashi, Tohru; Kawai, Jun; Kumagai, Hiroshi; Midorikawa, Katsumi; Tanihata, Isao; Hayashizaki, Yoshihide

2002-01-01

We have experimentally demonstrated femtosecond laser ablation for simultaneous atomization and ionization (fs-SAI) of organic molecules on solid substrates. We find most of the constituent atoms of organic molecules are atomized and ionized non-resonantly by femtosecond laser ablation. This observation is in contrast with that for the photoionization of cyclic aromatic hydrocarbons by femtosecond laser in the gas phase where little fragmentation has been observed. Crucial contribution of ablation plasma of solid sample to fs-SAI process is suggested. The ratio of natural abundance of stable isotopes contained in sample molecules is well reproduced, which confirms fs-SAI can be applied to the quantitative chemical analysis of isotope-labeled large organic molecules

The updated bottom up solution applied to atmospheric pressure photoionization and electrospray ionization mass spectrometry

Science.gov (United States)

The Updated Bottom Up Solution (UBUS) was recently applied to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAGs). This report demonstrates that the UBUS applies equally well to atmospheric pressure photoionization (APPI) MS and to electrospray ionizatio...

Evaluation of the capabilities of atmospheric pressure chemical ionization source coupled to tandem mass spectrometry for the determination of dioxin-like polychlorobiphenyls in complex-matrix food samples.

Science.gov (United States)

Portolés, T; Sales, C; Abalos, M; Sauló, J; Abad, E

2016-09-21

The use of the novel atmospheric pressure chemical ionization (APCI) source for gas chromatography (GC) coupled to triple quadrupole using tandem mass spectrometry (MS/MS) and its potential for the simultaneous determination of the 12 dioxin-like polychlorobiphenyls (DL-PCBs) in complex food and feed matrices has been evaluated. In first place, ionization and fragmentation behavior of DL-PCBs on the APCI source under charge transfer conditions has been studied followed by their fragmentation in the collision cell. Linearity, repeatability and sensitivity have been studied obtaining instrumental limits of detection and quantification of 0.0025 and 0.005 pg μL(-1) (2.5 and 5 fg on column) respectively for every DL-PCB. Finally, application to real samples has been carried out and DL-PCB congeners (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189) have been detected in the different samples in the range of 0.40-10000 pg g(-1). GC-(APCI)MS/MS has been proved as a suitable alternative to the traditionally accepted confirmation method based on the use of high resolution mass spectrometry and other triple quadrupole tandem mass spectrometry techniques operating with electron ionization. The development of MS/MS methodologies for the analysis of dioxins and DL-PCBs is nowadays particularly important, since this technique was included as a confirmatory method in the present European Union regulations that establish the requirements for the determination of these compounds in food and feed matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)

International Nuclear Information System (INIS)

Erdmann, N.; Herrmann, G.; Huber, G.; Koehler, S.; Kratz, J.V.; Mansel, A.; Nunnemann, M.; Passler, G.; Trautmann, N.; Waldek, A.

1997-01-01

Trace amounts of plutonium in the environment can be detected by resonance ionization mass spectroscopy (RIMS). An atomic beam of plutonium is produced after its chemical separation and deposition on a filament. The atoms are ionized by a three-step excitation using pulsed dye-lasers. The ions are mass-selectively detected in a time-of-flight (TOF) mass spectrometer. With this setup a detection limit of 1·10 6 atoms of plutonium has been achieved. Furthermore, the isotopic composition can be determined. Different samples, including soil from the Chernobyl area, IAEA-certified sediments from the Mururoa Atoll and urine, have been investigated. copyright 1997 American Institute of Physics

Analytical applications of resonance ionization mass spectrometry (RIMS)

International Nuclear Information System (INIS)

Fassett, J.D.; Travis, J.C.

1988-01-01

A perspective on the role of resonance ionization mass spectrometry (RIMS) in the field of analytical chemistry is presented. RIMS provides new, powerful, and complementary capabilities relative to traditional methods of inorganic mass spectrometry. Much of the initial work in RIMS has been to illustrate these capabilities and define the potential of RIMS in the generalized field of chemical analysis. Three areas of application are reviewed here: (1) noble gas measurements; (2) materials analysis using isotope dilution (IDMS); and, (3) solids analysis using direct sampling. The role of RIMS is discussed relative to the more traditional mass spectrometric methods of analysis in these areas. The applications are meant to illustrate the present state-of-the-art as well as point to the future state-of-the-art of RIMS in chemical analysis. (author)

Principles of interaction of ionizing radiation with matter and basic radiation chemistry processes

International Nuclear Information System (INIS)

Santar, I.; Bednar, J.

1976-01-01

The basic principles are given of the interaction of ionizing radiation with matter and the main trends are pointed out in radiation chemistry. A brief characteristics is given of the basic radiation chemical processes in gases and in the condensed phase, namely in water and in organic substances. (B.S.)

Simulation study of the ionizing front in the critical ionization velocity phenomenon

International Nuclear Information System (INIS)

Machida, S.; Goertz, C.K.; Lu, G.

1988-01-01

Simulations of the Critical Ionization Velocity (CIV) for a neutral gas cloud moving across the static magnetic field are made. We treat a low-β plasma and use a 2-1/2 D electrostatic code linked with our Plasma and Neutral Interaction Code (PANIC). Our study is focused on the understanding of the interface between the neutral gas cloud and the surrounding plasma where the strong interaction takes place. We assume the existence of some hot electrons in the ambient plasma to provide a seed ionization for CIV. When the ionization starts a sheath-like structure is formed at the surface of the neutral gas (Ionizing Front). In that region the crossfield component of the electric field causes the electron to E x B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. Thus the kinetic energy of the drifting electrons can be large enough for electron impact ionization. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the ionization front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating and additional ionization. The overall structure is studied by developing a simple analytic model as well as making simulation runs. (author)

In vitro evaluation of ionizing radiation effects in bone tissue by FTIR spectroscopy and dynamic mechanical analysis

International Nuclear Information System (INIS)

Veloso, Marcelo Noronha

2013-01-01

Ionizing radiation from gamma radiation sources or X-ray generators is frequently used in Medical Science, such as radiodiagnostic exams, radiotherapy, and sterilization of haloenxerts. Ionizing radiation is capable of breaking polypeptidic chains and causing the release of free radicals by radiolysis.of water. It interacts also with organic material at the molecular level, and it may change its mechanical properties. In the specific case of bone tissue, studies report that ionizing radiation induces changes in collagen molecules and reduces the density of intermolecular crosslinks. The aim of this study was to verify the changes promoted by different doses of ionizing radiation in bone tissue using Fourier Transform Infrared Spectroscopy (FTIR) and dynamic mechanical analysis (DMA). Samples of bovine bone were irradiated using Cobalt-60 with five different doses: 0.01 kGy, 0.1 kGy, 1 kGy, 15 kGy and 75 kGy. To study the effects of ionizing irradiation on the chemical structure of the bone, the sub-bands of amide I, the crystallinity index and relation of organic and inorganic materials, were studied. The mechanical changes were evaluated using the elastic modulus and the damping value. To verify whether the chemical changes and the mechanical characteristics of the bone were correlated, the relation between the analysis made with spectroscopic data and the mechanical analysis data was studied. It was possible to evaluate the effects of different doses of ionizing radiation in bone tissue. With ATR-FTIR spectroscopy, it was possible to observe changes in the organic components and in the hydroxyapatite crystals organization. Changes were also observed in the elastic modulus and in the damping value. High correlation with statistical significance was observed among (amide III + collagen)/ v1,v3 , PO 4 3- and the delta tangent, and among 1/FHWM and the elastic modulus. (author)

Introduction to ionizing radiation physics

International Nuclear Information System (INIS)

Musilek, L.

1979-01-01

Basic properties are described of the atom, atomic nucleus and of ionizing radiation particles; nuclear reactions, ionizing radiation sources and ionizing radiation interaction with matter are explained. (J.P.)

Collisional ionization

International Nuclear Information System (INIS)

Arnaud, M.

1985-07-01

In low density, thin plasmas (such as stellar coronae, interstellar medium, intracluster medium) the ionization process is governed by collision between electrons and ions in their ground state. In view of the recent improvements we thought an updating of ionization rates was really needed. The work is based on both experimental data and theoretical works and give separate estimates for the direct and autoionization rates

Synthesis of metal nanoparticles using ionizing radiation and developing their applications

International Nuclear Information System (INIS)

Ramnani, S.P.; Sabharwal, S.

2008-01-01

Fine metal particles with nanometer scale dimensions are of current interest due to their unusual properties that are different from their corresponding bulk materials. They are being explored for potential applications in optics, electronics, magnetics, catalyst, chemical sensing and biomedicine. A variety of methods are available in the literature for the synthesis of metal nanoparticles. The soft solution method involving the reduction of metal ion in the solution using reducing agent such as sodium borohydride, formaldehyde, trisodium citrate etc, are the most widely used. The ability of ionizing radiation to bring about ionization and excitation in the medium through which they travel results in the formation of reactive species which can be utilized to reduce metal ions into metal atoms to generate metal nanoparticles. The difference between gamma radiation method and soft solution method is that in the former the reducing species are generated in-situ whereas in later the reducing agent are incorporated into the system from an external source. A particular advantage of radiolysis method is that the reduction rate can be controlled by the selected dose rate unlike chemical method where the local concentration of reducing species is very high and cannot be controlled

Vectors to Increase Production Efficiency of Inducible Pluripotent Stem Cell (iPSC) | NCI Technology Transfer Center | TTC

Science.gov (United States)

This invention describes the discovery that specific p53 isoform increase the number of inducible pluripotent stem cells (iPS). It is known that the activity of p53 regulates the self-renewal and pluripotency of normal and cancer stem cells, and also affects re-programming efficiency of iPS cells. This p53 isoform-based technology provides a more natural process of increasing iPS cell production than previous methods of decreasing p53. NCI seeks licensees for this technology.

ANIONIC POLYMERIZATION OF ALKYL METHACRYLATES INITIATED BY nBuCu(NCy2)Li

Institute of Scientific and Technical Information of China (English)

Bing-yong Han; Jian-guo Liang; Jian-min Lu; Feng An; Wan-tai Yang

2009-01-01

Anionic polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and glycidyl methacrylate (GMA) initiated by nBuCu(NCy2)Li (1) in tetrahydrofuran (THF) at -50℃ to -10℃ was investigated. It was found that the polymerization of MMA and nBMA initiated by 1 proceeded quantitatively in THF to afford PMMA and PBMA with polydispersity index 1.15-1.30 and nearly 100% initiator efficiencies at -10℃. The molecular weights increased linearly with the ratio of [monomer]/[1]. However, a post-polymerization experiment carried out on this system revealed a double polymer peak by GPC when fresh monomer was added after an interval of 10 rain. Polymerization of styrene could be initiated by 1, but the initiator efficiency was low.

[Determination of short chain chlorinated paraffins in polyvinyl chloride plastics by gas chromatography-negative chemical ion/mass spectrometry].

Science.gov (United States)

Xing, Yuanna; Lin, Zhihui; Feng, Anhong; Wang, Xin; Gong, Yemeng; Chen, Zeyong

2015-02-01

A novel method was established to determine short chain chlorinated paraffins (SC-CPs) in polyvinyl chloride (PVC) plastics by gas chromatography-negative chemical ion/mass spectrometry (GC-NCI/MS). Ultrasonic extraction was used to extract SCCPs from PVC plastics. The optimal extraction time was 1.5 h, and concentrated sulfuric acid was adopted to purify the extracted solution. Finally, SCCPs in a sample were detected by GC-NCI/MS at 160 C and with methane reagent gas at 1. 5 mL/min. This method was not influenced by medium chain chlorinated paraffins (MCCPs) in the sample, and accurate quantitation was made for SCCPs. Twelve batches of samples were analyzed and SCCPs were detected in each batch with the contents from 0. 3 x 10(2)mg/kg to 3. 5 x 10(4)mg/kg. With respect to European limitation of SC-CPs (1%), four batches of samples did not comply with the European regulation, and they accounted for 33. 3%. Obviously, high SCCPs risk was presented in PVC plastics.

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

Science.gov (United States)

Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

2015-12-01

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laser mass spectrometry of chemical warfare agents using ultrashort laser pulses

International Nuclear Information System (INIS)

Weickhardt, C.; Grun, C.; Grotemeyer, J.

1998-01-01

Fast relaxation processes in excited molecules such as IC, ISC, and fragmentation are observed in many environmentally and technically relevant substances. They cause severe problems to resonance ionization mass spectrometry because they reduce the ionization yield and lead to mass spectra which do not allow the identification of the compound. By the use of ultrashort laser pulses these problems can be overcome and the advantages of REMPI over conventional ionization techniques in mass spectrometry can be regained. This is demonstrated using soil samples contaminated with a chemical warfare agent

Systematic trends in photonic reagent induced reactions in a homologous chemical family.

Science.gov (United States)

Tibbetts, Katharine Moore; Xing, Xi; Rabitz, Herschel

2013-08-29

The growing use of ultrafast laser pulses to induce chemical reactions prompts consideration of these pulses as "photonic reagents" in analogy to chemical reagents. This work explores the prospect that photonic reagents may affect systematic trends in dissociative ionization reactions of a homologous family of halomethanes, much as systematic outcomes are often observed for reactions between homologous families of chemical reagents and chemical substrates. The experiments in this work with photonic reagents of varying pulse energy and linear spectral chirp reveal systematic correlations between observable ion yields and the following set of natural variables describing the substrate molecules: the ionization energy of the parent molecule, the appearance energy of each fragment ion, and the relative strength of carbon-halogen bonds in molecules containing two different halogens. The results suggest that reactions induced by photonic reagents exhibit systematic behavior analogous to that observed in reactions driven by chemical reagents, which provides a basis to consider empirical "rules" for predicting the outcomes of photonic reagent induced reactions.

First successful ionization of Lr (Z = 103) by a surface-ionization technique

Energy Technology Data Exchange (ETDEWEB)

Sato, Tetsuya K., E-mail: sato.tetsuya@jaea.go.jp; Sato, Nozomi; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Ooe, Kazuhiro; Miyashita, Sunao; Schädel, Matthias [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kaneya, Yusuke; Nagame, Yuichiro [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512 (Japan); Osa, Akihiko [Department of Research Reactor and Tandem Accelerator, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Ichikawa, Shin-ichi [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Stora, Thierry [ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); Kratz, Jens Volker [Institut für Kernchemie, Universität Mainz, D-55099 Mainz (Germany)

2013-02-15

We have developed a surface ionization ion-source as part of the JAEA-ISOL (Isotope Separator On-Line) setup, which is coupled to a He/CdI{sub 2} gas-jet transport system to determine the first ionization potential of the heaviest actinide lawrencium (Lr, Z = 103). The new ion-source is an improved version of the previous source that provided good ionization efficiencies for lanthanides. An additional filament was newly installed to give better control over its operation. We report, here, on the development of the new gas-jet coupled surface ion-source and on the first successful ionization and mass separation of 27-s {sup 256}Lr produced in the {sup 249}Cf + {sup 11}B reaction.

A compact high resolution electrospray ionization ion mobility spectrometer.

Science.gov (United States)

Reinecke, T; Kirk, A T; Ahrens, A; Raddatz, C-R; Thoben, C; Zimmermann, S

2016-04-01

Electrospray is a commonly used ionization method for the analysis of liquids. An electrospray is a dispersed nebular of charged droplets produced under the influence of a strong electrical field. Subsequently, ions are produced in a complex process initiated by evaporation of neutral solvent molecules from these droplets. We coupled an electrospray ionization source to our previously described high resolution ion mobility spectrometer with 75 mm drift tube length and a drift voltage of 5 kV. When using a tritium source for chemical gas phase ionization, a resolving power of R=100 was reported for this setup. We replaced the tritium source and the field switching shutter by an electrospray needle, a desolvation region with variable length and a three-grid shutter for injecting ions into the drift region. Preliminary measurements with tetraalkylammonium halides show that the current configuration with the electrospray ionization source maintains the resolving power of R=100. In this work, we present the characterization of our setup. One major advantage of our setup is that the desolvation region can be heated separately from the drift region so that the temperature in the drift region stays at room temperature even up to desolvation region temperatures of 100 °C. We perform parametric studies for the investigation of the influence of temperature on solvent evaporation with different ratios of water and methanol in the solvent for different analyte substances. Furthermore, the setup is operated in negative mode and spectra of bentazon with different solvents are presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D{sub 2}O ice beneath a H{sub 2}O ice layer

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui, E-mail: ryang73@ustc.edu; Gudipati, Murthy S., E-mail: gudipati@jpl.nasa.gov [Science Division, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2014-03-14

In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D{sub 2}O ices by novel infrared (IR) laser ablation of a layered non-absorbing D{sub 2}O ice (spectator) containing the analytes and an ablation-active IR-absorbing H{sub 2}O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H{sub 2}O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D{sub 2}O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D{sub 2}O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H{sub 2}O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and

Identifying the related compounds using electrospray ionization tandem mass spectrometry: bromotyrosine alkaloids from marine sponge Psammaplysilla purpurea

Digital Repository Service at National Institute of Oceanography (India)

Tilvi, S.; DeSouza, L.

electrospray ionization tandem mass spectrometry (ESI-MS/MS). This sponge has tremendous chemical diversity of bromotyrosine alkaloids. Here we have used the proteomics approach in identifying related bromotyrosine alkaloids based on the predicated mass...

Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

DEFF Research Database (Denmark)

Nielsen, S. E.; Freese, R.; Cornett, Claus

2000-01-01

A rapid and sensitive high-performance liquid chromatographic mass spectrometric (HPLC-MS) method is described for the determination and quantification of 12 dietary flavonoid glycosides and aglycons in human urine samples. Chromatographic separation of the analytes of interest was achieved...... by column-switching, using the first column (a Zorbax 300SB C-3 column) for sample cleanup and eluting the heart-cut flavonoid fraction onto the second column (a Zorbax SE C-18 column) for separation and detection by ultraviolet and atmospheric pressure chemical ionization MS using single ion monitoring...... of variation for the analysis of the 12 different flavonoids in quality control urine samples were 12.3% on average (range 11.0-13.7%, n = 24, reproducibility) and the repeatability of the assay were 5.0% (mean, range 0.1-14.8%, it = 12). A subset of 10 urine samples from a human dietary intervention study...

Spectroscopic determination of ionization constants of quinoline and 3-aminoquinoline at different temperature

International Nuclear Information System (INIS)

Indhar, H.A.B.

2000-01-01

Quinoline and its derivative are chemically and biologically important heterocylic compounds. Its ionization constant (pK/sub a/ values have been previously determined only at 18 or 20 deg. C. We have enhanced this work at different temperatures from 20-50 deg. C at the interval of 5 deg. C. The dissociation constants (pk/sub a/s), and Gibb's free energies of quinoline and 3-aminoquinoline have been determined by UV-Spectrophotometer (lambda 2) equipped with a temperature control of - + 0.1 deg. C at temperatures ranging from 20-50 deg. C in water. The experimental data have been used for the determination of thermodynamic ionization constants (pk /sub a //sup t/) sub t/, concentration ionization constants (pK/sub a//sup M/) and Gibbs's free energy values of pK/sub a/sup M/. The ionization constant values decrease with increase of temperature. The significance of relative magnitudes of the values is discussed and some useful generalization are obtained. The curves are parabolic. A computer program in GW-BASIC calculates the values of dissociation constants. From the pK/sub a/ values, Gibb's free energies are compared and discussed. (author)

Ionization chamber

International Nuclear Information System (INIS)

Jilbert, P.H.

1975-01-01

The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

Science.gov (United States)

Wei, Fang; Hu, Na; Lv, Xin; Dong, Xu-Yan; Chen, Hong

2015-07-24

In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed

Plasma production via field ionization

Directory of Open Access Journals (Sweden)

C. L. O’Connell

2006-10-01

Full Text Available Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch, or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam’s bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

Ionization of anisothermal plasmas. Ionisation des plasmas polythermes

Energy Technology Data Exchange (ETDEWEB)

Dennery, F.M.

1994-01-01

During this last mid-century, only the temperature of electrons has been involved in the Saha's mass action law, whatever be the other ionic and neutral ones in any isothermal or anisothermal plasma. In order to set aside this underlying paradox in the case of argon ionization, it is necessary to improve this equation of partial equilibrium after having defined: - the basic Gibbs-Duhem's relations for such a polythermal mixture, - the inhomogeneous equilibrium issued from chemical reactions according to Le Chatelier's principle. (author). 3 refs.

Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of p-chlorofluorobenzene

Science.gov (United States)

Tuttle, William D.; Gardner, Adrian M.; Wright, Timothy G.

2017-09-01

The S1 ← S0 (A˜1 B2 ← X˜1 A1) electronic transition of para-chlorofluorobenzene has been investigated using resonance-enhanced multiphoton ionization (REMPI) spectroscopy. Assignment of the vibrational structure has been achieved by comparison with corresponding spectra of related molecules, via quantum chemical calculations, and via shifts in bands between the spectra of the 35Cl and 37Cl isotopologues. In addition, we have also partially reassigned a previously-published spectrum of para-dichlorobenzene.

Fast combustion waves and chemi-ionization processes in a flame initiated by a powerful local plasma source in a closed reactor

Science.gov (United States)

Artem'ev, K. V.; Berezhetskaya, N. K.; Kazantsev, S. Yu.; Kononov, N. G.; Kossyi, I. A.; Popov, N. A.; Tarasova, N. M.; Filimonova, E. A.; Firsov, K. N.

2015-01-01

Results are presented from experimental studies of the initiation of combustion in a stoichiometric methane–oxygen mixture by a freely localized laser spark and by a high-current multispark discharge in a closed chamber. It is shown that, preceding the stage of ‘explosive’ inflammation of a gas mixture, there appear two luminous objects moving away from the initiator along an axis: a relatively fast and uniform wave of ‘incomplete combustion’ under laser spark ignition and a wave with a brightly glowing plasmoid behind under ignition from high-current slipping surface discharge. The gas mixtures in both the ‘preflame’ and developed-flame states are characterized by a high degree of ionization as the result of chemical ionization (plasma density ne≈1012 cm−3) and a high frequency of electron–neutral collisions (νen≈1012 s−1). The role of chemical ionization in constructing an adequate theory for the ignition of a gas mixture is discussed. The feasibility of the microwave heating of both the preflame and developed-flame plasma, supplementary to a chemical energy source, is also discussed. PMID:26170426

Ionizing radiation in hospitals

International Nuclear Information System (INIS)

Blok, K.; Ginkel, G. van; Leun, K. van der; Muller, H.; Oude Elferink, J.; Vesseur, A.

1985-10-01

This booklet dels with the risks of the use of ionizing radiation for people working in a hospital. It is subdivided in three parts. Part 1 treats the properties of ionizing radiation in general. In part 2 the various applications are discussed of ionizing radiation in hospitals. Part 3 indicates how a not completely safe situation may be improved. (H.W.). 14 figs.; 4 tabs

Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

KAUST Repository

Hourani, Nadim; Andersson, Jan T.; Mö ller, Isabelle; Amad, Maan H.; Witt, Matthí as; Sarathy, Mani

2013-01-01

oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same

On energetics of hydrocarbon chemical reactions by ionizing irradiation

International Nuclear Information System (INIS)

Zaykin, Yu.A.; Zaykina, R.F.; Mirkin, G.

2002-01-01

Complete text of publication follows. The present global energy crisis requires the industry to look for technologies that are more effective and, particularly, less energy consuming. The hydrocarbon processing technology based on the electron radiation-induced thermal chemical conversion has a great potential. Comparing the presently predominant thermocatalytic processing, it is much more energy efficient, because chemical conversions go at a minimal processing temperature and pressure. To compare energy consumption by electron irradiation with thermal and thermocatalytic technologies of hydrocarbon processing one must see major differences between them. While traditional thermocatalytic processes are equilibrium and their energetics can be evaluated based on principles of classic thermodynamics, HEET processing is non-equilibrium and this evaluation approach is not valid for it. However, a theoretical description of radiation-chemical conversion using reaction rate constants determined in thermally equilibrium systems is approximately adequate to radiation processes by substituting equilibrium concentrations of reacting particles as their non-equilibrium concentrations under irradiation. In particular, description of radical reactions initiated by radiation requires substitution of thermally equilibrium radical concentration by much higher concentration defined by the dynamic equilibrium of radical radiation generation and their recombination. The paper presents the comparative analysis of energy consumption in different stages of hydrocarbon processing using classic thermal cracking by heating versus radiation induced cracking. It is shown that in the most energy-consuming stage of processing - the chain reaction initiation necessary for concentration of active radicals, irradiation processing has the great advantage compared to thermal cracking by heating and allows cutting down the total energy consumption by approximately 40%

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids

International Nuclear Information System (INIS)

Raro, M.; Portolés, T.; Pitarch, E.; Sancho, J.V.; Hernández, F.; Garrostas, L.; Marcos, J.; Ventura, R.; Segura, J.; Pozo, O.J.

2016-01-01

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid–liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H] + or [M + H-2TMSOH] + ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL −1 . Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. - Highlights: • APCI source has been evaluated for the screening of 16 exogenous AAS in urine. • Suitable precision was

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids

Energy Technology Data Exchange (ETDEWEB)

Raro, M.; Portolés, T.; Pitarch, E.; Sancho, J.V.; Hernández, F. [Research Institute for Pesticides and Water, University Jaume I, E-12071 Castellón (Spain); Garrostas, L. [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain); Marcos, J.; Ventura, R.; Segura, J. [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain); Department of Experimental and Health Sciencies, Universitat Pompeu Fabra, Doctor Aiguader 88, 08003 Barcelona (Spain); Pozo, O.J., E-mail: opozo@imim.es [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain)

2016-02-04

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid–liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H]{sup +} or [M + H-2TMSOH]{sup +} ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL{sup −1}. Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. - Highlights: • APCI source has been evaluated for the screening of 16 exogenous AAS in urine. • Suitable

Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

Science.gov (United States)

Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

2015-06-01

Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

Chemical ionisation mass spectrometry: a survey of instrument technology

International Nuclear Information System (INIS)

Mather, R.E.; Todd, J.F.J.

1979-01-01

The purpose of this review is to survey the innovations and improvements which have been made in both instrumentation and methodology in chemical ionization mass spectrometry in the past ten years. (Auth.)

Miniature ionization chamber

International Nuclear Information System (INIS)

Alexeev, V.I.; Emelyanov, I.Y.; Ivanov, V.M.; Konstantinov, L.V.; Lysikov, B.V.; Postnikov, V.V.; Rybakov, J.V.

1976-01-01

A miniature ionization chamber having a gas-filled housing which accommodates a guard electrode made in the form of a hollow perforated cylinder is described. The cylinder is electrically associated with the intermediate coaxial conductor of a triaxial cable used as the lead-in of the ionization chamber. The gas-filled housing of the ionization chamber also accommodates a collecting electrode shaped as a rod electrically connected to the center conductor of the cable and to tubular members. The rod is disposed internally of the guard electrode and is electrically connected, by means of jumpers passing through the holes in the guard electrode, to the tubular members. The tubular members embrace the guard electrode and are spaced a certain distance apart along its entire length. Arranged intermediate of these tubular members are spacers secured to the guard electrode and fixing the collecting electrode throughout its length with respect to the housing of the ionization chamber

Increased ionization rate in laser enrichment

International Nuclear Information System (INIS)

Janes, G.S.; Pike, G.T.

1977-01-01

A system employing multiple, upper excitation levels in a technique for isotopically selective ionization to improve the ionization efficiency is described. Laser radiation is employed to excite particles with isotopic selectivity. Excitation is produced to a plurality of excited states below the ionization level with the result of increasing the number of available excited particles for ionization and thereby increasing the ionization cross section for improved system efficiency

Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

DEFF Research Database (Denmark)

Andersen, Jens S.; Svensson, B; Roepstorff, P

1996-01-01

Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

Prediction Of pKa From Chemical Structure Using Free And Open-Source Tools

Science.gov (United States)

The ionization state of a chemical, reflected in pKa values, affects lipophilicity, solubility, protein binding and the ability of a chemical to cross the plasma membrane. These properties govern the pharmacokinetic parameters such as absorption, distribution, metabolism, excreti...

El procés d'avaluació i intervenció psicològica a pacients amb trastorns per abús d' alcohol i/o altres substàncies psicotròpiques

OpenAIRE

Trasovares Navarrete, María Victoria

2004-01-01

Aquest treball, realitzat al Centre d'Atenció i Seguiment de Drogodependències (CASD) de Nou Barris, ha tingut com a objectiu principal observar el rol del psicòleg clínic en el procés d'avaluació i intervenció psicoterapèutica en pacients que presenten un trastorn per dependència de substàncies psicotròpiques. Este trabajo, realizado en el Centro de Atención y Seguimiento de Drogodependencias (CASD) de Nou Barris, ha tenido como principal objetivo observar el rol del psicólogo clínico en ...

Protocol per a la implantació d’eines didàctiques virtuals: competències i habilitats adquirides pels estudiants

Directory of Open Access Journals (Sweden)

Laura Guitart Tarrés

2011-06-01

Full Text Available L’adaptació al nou espai europeu d’educació superior (EEES ha plantejat alguns canvis en l’enfocament de la formació universitària al nostre país. On abans era el docent el protagonista, ara és l’estudiant el que pren el rol d’actor principal de la seva formació, i l’aprenentatge s’orienta cap a una autonomia i reflexió més grans. En aquest escenari, les noves tecnologies ofereixen un ampli ventall d’opcions per millorar els processos formatius. En aquests sentit, el Grup d’Innovació Docent G•IDEA ha participat activament en aquest procés d’adaptació des de ja fa uns quants anys, i ha creat una sèrie de recursos docents digitals que han estat àmpliament provats en diversos ensenyaments de la Facultat d’Economia i Empresa de la Universitat de Barcelona. L’objectiu d’aquest article és presentar el protocol dissenyat per l’equip d’investigadors del G•IDEA per implantar aquestes eines didàctiques (webquestes i exercicis tutoritzats, i també els resultats d’una enquesta de satisfacció sobre les competències i habilitats adquirides pels nostres estudiants en la utilització dels recursos. Els resultats mostren, d’una banda, que no ha estat possible crear un mateix protocol aplicable a tots els recursos, a causa de les diferències en els objectius didàctics de les distintes eines docents implantades. D’altra banda, la valoració que els estudiants fan de la utilització de les eines és molt positiva, tot i que hi ha algunes diferències entre els recursos analitzats. Conèixer la valoració que l’alumnat fa d’aquests recursos permet al grup d’investigadors poder-los millorar i adequar al perfil dels estudiants perquè aquests en puguin treure el màxim profit possible.

NCI Program for Natural Product Discovery: A Publicly-Accessible Library of Natural Product Fractions for High-Throughput Screening.

Science.gov (United States)

Thornburg, Christopher C; Britt, John R; Evans, Jason R; Akee, Rhone K; Whitt, James A; Trinh, Spencer K; Harris, Matthew J; Thompson, Jerell R; Ewing, Teresa L; Shipley, Suzanne M; Grothaus, Paul G; Newman, David J; Schneider, Joel P; Grkovic, Tanja; O'Keefe, Barry R

2018-06-13

The US National Cancer Institute's (NCI) Natural Product Repository is one of the world's largest, most diverse collections of natural products containing over 230,000 unique extracts derived from plant, marine, and microbial organisms that have been collected from biodiverse regions throughout the world. Importantly, this national resource is available to the research community for the screening of extracts and the isolation of bioactive natural products. However, despite the success of natural products in drug discovery, compatibility issues that make extracts challenging for liquid handling systems, extended timelines that complicate natural product-based drug discovery efforts and the presence of pan-assay interfering compounds have reduced enthusiasm for the high-throughput screening (HTS) of crude natural product extract libraries in targeted assay systems. To address these limitations, the NCI Program for Natural Product Discovery (NPNPD), a newly launched, national program to advance natural product discovery technologies and facilitate the discovery of structurally defined, validated lead molecules ready for translation will create a prefractionated library from over 125,000 natural product extracts with the aim of producing a publicly-accessible, HTS-amenable library of >1,000,000 fractions. This library, representing perhaps the largest accumulation of natural-product based fractions in the world, will be made available free of charge in 384-well plates for screening against all disease states in an effort to reinvigorate natural product-based drug discovery.

Improving clinical research and cancer care delivery in community settings: evaluating the NCI community cancer centers program

Directory of Open Access Journals (Sweden)

Fennell Mary L

2009-09-01

Full Text Available Abstract Background In this article, we describe the National Cancer Institute (NCI Community Cancer Centers Program (NCCCP pilot and the evaluation designed to assess its role, function, and relevance to the NCI's research mission. In doing so, we describe the evolution of and rationale for the NCCCP concept, participating sites' characteristics, its multi-faceted aims to enhance clinical research and quality of care in community settings, and the role of strategic partnerships, both within and outside of the NCCCP network, in achieving program objectives. Discussion The evaluation of the NCCCP is conceptualized as a mixed method multi-layered assessment of organizational innovation and performance which includes mapping the evolution of site development as a means of understanding the inter- and intra-organizational change in the pilot, and the application of specific evaluation metrics for assessing the implementation, operations, and performance of the NCCCP pilot. The assessment of the cost of the pilot as an additional means of informing the longer-term feasibility and sustainability of the program is also discussed. Summary The NCCCP is a major systems-level set of organizational innovations to enhance clinical research and care delivery in diverse communities across the United States. Assessment of the extent to which the program achieves its aims will depend on a full understanding of how individual, organizational, and environmental factors align (or fail to align to achieve these improvements, and at what cost.

Notes on free radicals in the field of human and environmental protection against ionizing radiations

International Nuclear Information System (INIS)

Bittel, R.

It is well known that ionizing radiations, in vitro and in vivo produce, free radicals which may be considered as mediators between physical agents and biological targets. Some aspects of this vast problem are accentuated. Ionizing radiations act either directly on the organic molecules of tissues or indirectly by creating, in the surroundings and in tissular water, inorganic free radicals which act on biochemical molecules to gives new radicals. Analysis of the free radical initiation phenomenon in vivo shows that many initiating agents exist, ionizing radiations representing only one group. The role of oxydants, especially oxydising polluants, and the part played by various enzyme systems (super-oxide dismutase, oxydases etc...) are emphasized. After propagation the chain reactions end in combinations between radicals are stopped by certain organic molecules (radical scavengers). Examples are given (free radical formation from compounds of great biological importance: puric and pyrimidic bases, nucleic acids in particular). These aspects are discussed from the viewpoint of their effects on human and environmental protection against both ionizing radiations and certain chemical pollution [fr

The study of thermodynamic properties and transport properties of multicomponent systems with chemical reactions

Directory of Open Access Journals (Sweden)

Samujlov E.

2013-04-01

Full Text Available In case of system with chemical reaction the most important properties are heat conductivity and heat capacity. In this work we have considered the equation for estimate the component of these properties caused by chemical reaction and ionization processes. We have evaluated the contribution of this part in heat conductivity and heat capacity too. At the high temperatures contribution in heat conductivity from ionization begins to play an important role. We have created a model, which describe partial and full ionization of gases and gas mixtures. In addition, in this work we present the comparison of our result with experimental data and data from numerical simulation. We was used the data about transport properties of middle composition of Russian coals and the data of thermophysical properties of natural gas for comparison.

Inactivated Tianjin strain, a novel genotype of Sendai virus, induces apoptosis in HeLa, NCI-H446 and Hep3B cells.

Science.gov (United States)

Chen, Jun; Han, Han; Wang, Bin; Shi, Liying

2016-07-01

The Sendai virus strain Tianjin is a novel genotype of the Sendai virus. In previous studies, ultraviolet-inactivated Sendai virus strain Tianjin (UV-Tianjin) demonstrated antitumor effects on human breast cancer cells. The aim of the present study was to investigate the in vitro antitumor effects of UV-Tianjin on the human cervical carcinoma HeLa, human small cell lung cancer NCI-H446 and human hepatocellular carcinoma Hep 3B cell lines, and the possible underlying mechanisms of these antitumor effects. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay revealed that UV-Tianjin treatment inhibited the proliferation of HeLa, NCI-H446 and Hep 3B cells in a dose- and time-dependent manner. Hoechst and Annexin V-fluorescein isothiocyanate/propidium iodide double staining indicated that UV-Tianjin induced dose-dependent apoptosis in all three cell lines with the most significant effect observed in the HeLa cell line. In the HeLa cell line, UV-Tianjin-induced apoptosis was further confirmed by the disruption of the mitochondria membrane potential and the activation of caspases, as demonstrated by fluorescent cationic dye and colorimetric assays, respectively. In addition, western blot analysis revealed that UV-Tianjin treatment resulted in significant upregulation of cytochrome c , apoptosis protease activating factor-1, Fas, Fas ligand and Fas-associated protein with death domain, and activated caspase-9, -8 and -3 in HeLa cells. Based on these results, it is hypothesized that UV-Tianjin exhibits anticancer activity in HeLa, NCI-H446 and Hep 3B cell lines via the induction of apoptosis. In conclusion, the results of the present study indicate that in the HeLa cell line, intrinsic and extrinsic apoptotic pathways may be involved in UV-Tianjin-induced apoptosis.

Primary emissions and chemical oxidation of volatile organic compounds emitted from laboratory biomass burning sources during the 2016 FIREX FireLab campaign: measurements from a H3O+ chemical ionization mass spectrometer

Science.gov (United States)

Coggon, M. M.; Warneke, C.; Koss, A.; Sekimoto, K.; Yuan, B.; Lim, C. Y.; Hagan, D. H.; Kroll, J. H.; Cappa, C. D.; Gilman, J.; Lerner, B. M.; Jimenez, J. L.; Yokelson, R. J.; Roberts, J. M.; De Gouw, J. A.

2017-12-01

Non-methane organic gases (NMOG) emitted by biomass burning constitute a large source of reactive carbon in the atmosphere. Once emitted, these compounds may undergo series of reactions with the OH radical and nitrogen oxides to form secondary organic aerosol (SOA), ozone, or other health-impacting products. The complex emission profile and strong variability of biomass burning NMOG play an important, yet understudied, role in the variability of air quality outcomes such as SOA and ozone. In this study, we summarize measurements of biomass burning volatile organic compounds (VOCs) conducted using a H3O+ chemical ionization mass spectrometer (H3O+-CIMS) during the 2016 FIREX laboratory campaign in Missoula, MT. Specifically, we will present data demonstrating the chemical evolution of biomass burning VOCs artificially aged in a field-deployable photooxidation chamber and an oxidation flow reactor. More than 50 OH-oxidation experiments were conducted with biomass types representing a range of North American fuels. Across many fuel types, VOCs with high SOA and ozone formation potential, such as aromatics and furans, were observed to quickly react with the OH radical while oxidized species were generated. We compare the calculated OH reactivity of the primary emissions to the calculated OH reactivity used in many photochemical models and highlight areas requiring additional research in order to improve model/measurement comparisons.

NON-EQUILIBRIUM IONIZATION MODELING OF THE CURRENT SHEET IN A SIMULATED SOLAR ERUPTION

International Nuclear Information System (INIS)

Shen Chengcai; Reeves, Katharine K.; Raymond, John C.; Murphy, Nicholas A.; Ko, Yuan-Kuen; Lin Jun; Mikić, Zoran; Linker, Jon A.

2013-01-01

The current sheet that extends from the top of flare loops and connects to an associated flux rope is a common structure in models of coronal mass ejections (CMEs). To understand the observational properties of CME current sheets, we generated predictions from a flare/CME model to be compared with observations. We use a simulation of a large-scale CME current sheet previously reported by Reeves et al. This simulation includes ohmic and coronal heating, thermal conduction, and radiative cooling in the energy equation. Using the results of this simulation, we perform time-dependent ionization calculations of the flow in a CME current sheet and construct two-dimensional spatial distributions of ionic charge states for multiple chemical elements. We use the filter responses from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory and the predicted intensities of emission lines to compute the count rates for each of the AIA bands. The results show differences in the emission line intensities between equilibrium and non-equilibrium ionization. The current sheet plasma is underionized at low heights and overionized at large heights. At low heights in the current sheet, the intensities of the AIA 94 Å and 131 Å channels are lower for non-equilibrium ionization than for equilibrium ionization. At large heights, these intensities are higher for non-equilibrium ionization than for equilibrium ionization inside the current sheet. The assumption of ionization equilibrium would lead to a significant underestimate of the temperature low in the current sheet and overestimate at larger heights. We also calculate the intensities of ultraviolet lines and predict emission features to be compared with events from the Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric Observatory, including a low-intensity region around the current sheet corresponding to this model

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 1 ... potential for immobilization and disposal of high level nuclear waste, was developed. ... on the fission product substituted NZP sintered at 1000°C, in pure de-ionized water ...

On the ionization of interstellar magnesium

International Nuclear Information System (INIS)

Gurzadyan, G.A.

1977-01-01

It has been shown that two concentric ionization zones of interstellar magnesium must exist around each star: internal, with a radius coinciding with that of the zone of hydrogen ionization Ssub(H); and external, with a radius greater than Ssub(H), by one order. Unlike interstellar hydrogen, interstellar magnesium is ionized throughout the Galaxy. It also transpires that the ionizing radiation of ordinary hot stars cannot provide for the observed high degree of ionization of interstellar magnesium. The discrepance can be eliminated by assuming the existence of circumstellar clouds or additional ionization sources of interstellar magnesium (X-ray background radiation, high-energy particles, etc.). Stars of the B5 and BO class play the main role in the formation of ionization zones of interstellar magnesium; the contribution of O class stars is negligible (<1%). (Auth.)

Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

Science.gov (United States)

Winter, Gregory T.; Wilhide, Joshua A.; LaCourse, William R.

2016-02-01

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

Sodium ionization detector and sensor

International Nuclear Information System (INIS)

Hrizo, J.; Bauerle, J.E.

1979-01-01

Work conducted on a basic technology development effort with the Westinghouse Sodium Ionization Detector (SID) sensor is reported. Included are results obtained for three task areas: (1) On-line operational response testing - in-situ calibration techniques; (2) Performance-reliability characteristics of aged filaments; and (3) Evaluation of chemical interference effects. The results showed that a calibrator filament coated with a sodium compound, when activated, does supply the necessary sodium atoms to provide a valid operational in-situ test. The life time of new Cr 2 0 3 -protected SID sensor filaments can be extended by operating at a reduced temperature. However, there also is a reduction in the sensitivity. Non-sodium species, such as products from a smoldering fire and organic aerosols, produce an interference response from the sensor comparable to a typical sodium response

Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions

International Nuclear Information System (INIS)

Pajek, M.; Banas, D.; Semaniak, J.; Braziewicz, J.; Majewska, U.; Chojnacki, S.; Czyzewski, T.; Fijal, I.; Jaskola, M.; Glombik, A.; Kretschmer, W.; Trautmann, D.; Lapicki, G.; Mukoyama, T.

2003-01-01

The multiple-ionization and coupling effects in L-shell ionization of atoms by heavy-ion impact have been studied by measuring the L x-ray production cross sections in solid targets of Au, Bi, Th, and U bombarded by oxygen ions in the energy range 6.4-70 MeV. The measured L x-ray spectra were analyzed using the recently proposed method accounting for the multiple-ionization effects, such as x-ray line shifting and broadening, which enables one to obtain the ionization probabilities for outer shells. The L-subshell ionization cross sections have been obtained from measured x-ray production cross sections for resolved Lα 1,2 , Lγ 1 , and Lγ 2,3 transitions using the L-shell fluorescence and Coster-Kronig yields being substantially modified by the multiple ionization in the M and N shells. In particular, the effect of closing of strong L 1 -L 3 M 4,5 Coster-Kronig transitions in multiple-ionized atoms was evidenced and discussed. The experimental ionization cross sections for the L 1 , L 2 , and L 3 subshells have been compared with the predictions of the semiclassical approximation (SCA) and the ECPSSR theory that includes the corrections for the binding-polarization effect within the perturbed stationary states approximation, the projecticle energy loss, and Coulomb deflection effects as well as the relativistic description of inner-shell electrons. These approaches were further modified to include the L-subshell couplings within the ''coupled-subshell model'' (CSM). Both approaches, when modified for the coupling effects, are in better agreement with the data. Particularly, the predictions of the SCA-CSM calculations reproduce the experimental L-subshell ionization cross section reasonably well. Remaining discrepancies are discussed qualitatively, in terms of further modifications of the L-shell decay rates caused by a change of electronic wave functions in multiple-ionized atoms

Dual ionization chamber

International Nuclear Information System (INIS)

Mallory, J.; Turlej, Z.

1981-01-01

Dual ionization chambers are provided for use with an electronic smoke detector. The chambers are separated by electrically-conductive partition. A single radiation source extends through the partition into both chambers, ionizing the air in each. The mid-point current of the device may be balanced by adjusting the position of the source

Resonance ionization scheme development for europium

Energy Technology Data Exchange (ETDEWEB)

Chrysalidis, K., E-mail: katerina.chrysalidis@cern.ch; Goodacre, T. Day; Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Naubereit, P. [Johannes Gutenberg-Universität, Institiut für Physik (Germany); Rothe, S.; Seiffert, C. [CERN (Switzerland); Kron, T.; Wendt, K. [Johannes Gutenberg-Universität, Institiut für Physik (Germany)

2017-11-15

Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.

In vitro transformation: interactions of chemical carcinogens and radiation

International Nuclear Information System (INIS)

DiPaolo, J.A.

1976-01-01

The development of reproducible quantitative in vitro procedures resulting in neoplastic transformation of mammalian cells has made possible the separation of events related to the process leading to transformation from secondary events that interfere with the early recognition of transformation. The use of chemical carcinogens on Syrian hamster cell strains results in a dose-response relation consistent with a Poisson distribution, indicating that the transformation phenomenon is inductive. In some circumstances, the joint action or interaction of chemical carcinogens with other agents results in an increased incidence of transformation. The pretreatment of Syrian hamster cells with ionizing radiation (250 R) or alkylating chemicals enhances the frequency of transformation on a cell or colony basis ordinarily obtained with known chemical carcinogens. Pretreatment with non-ionizing irradiation (uv, 254 nm) did not have a similar effect. The two types of irradiation and the alkylating agents reduced the cloning efficiency of the cells. X ray alone produced no transformation; the alkylating chemicals produced transformations infrequently, whereas uv produced a significant number of transformations. The number of transformations associated with uv is increased by pretreatment of the cells by x-irradiation. The enhancement of transformation by x-ray or x-ray-type agents appears to be independent of the type of second carcinogen used

Measurement of low-ppm mixing ratios of water vapor in the upper troposphere and lower stratosphere using chemical ionization mass spectrometry

Directory of Open Access Journals (Sweden)

T. D. Thornberry

2013-06-01

Full Text Available A chemical ionization mass spectrometer (CIMS instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS. A low-pressure flow of sample air passes through an ionization volume containing an α-particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+ from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45 min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm, 10−6 mol mol−1 generated by Pt-catalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB-57F high-altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1 s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hz ppm−1 at 3 ppm with a signal to noise ratio (2 σ, 1 s greater than 32. The total measurement uncertainty was 9 to 11%, derived from the uncertainty in the in situ calibrations.

Examination and Manipulation of Protein Surface Charge in Solution with Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Gross, Deborah S.; Van Ryswyk, Hal

2014-01-01

Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool for examining the charge of proteins in solution. The charge can be manipulated through choice of solvent and pH. Furthermore, solution-accessible, protonated lysine side chains can be specifically tagged with 18-crown-6 ether to form noncovalent adducts. Chemical derivatization…

The yield, processing, and biological consequences of clustered DNA damage induced by ionizing radiation

International Nuclear Information System (INIS)

Shikazono, Naoya; Noguchi, Miho; Fujii, Kentaro; Urushibara, Ayumi; Yokoya, Akinari

2009-01-01

After living cells are exposed to ionizing radiation, a variety of chemical modifications of DNA are induced either directly by ionization of DNA or indirectly through interactions with water-derived radicals. The DNA lesions include single strand breaks (SSB), base lesions, sugar damage, and apurinic/apyrimidinic sites (AP sites). Clustered DNA damage, which is defined as two or more of such lesions within one to two helical turns of DNA induced by a single radiation track, is considered to be a unique feature of ionizing radiation. A double strand break (DSB) is a type of clustered DNA damage, in which single strand breaks are formed on opposite strands in close proximity. Formation and repair of DSBs have been studied in great detail over the years as they have been linked to important biological endpoints, such as cell death, loss of genetic material, chromosome aberration. Although non-DSB clustered DNA damage has received less attention, there is growing evidence of its biological significance. This review focuses on the current understanding of (1) the yield of non-DSB clustered damage induced by ionizing radiation (2) the processing, and (3) biological consequences of non-DSB clustered DNA damage. (author)

Coffee-ring effects in laser desorption/ionization mass spectrometry.

Science.gov (United States)

Hu, Jie-Bi; Chen, Yu-Chie; Urban, Pawel L

2013-03-05