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Sample records for rayonnements ionisants cancers

  1. Influence du traitement ionisant par rayonnement γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale

    NASA Astrophysics Data System (ADS)

    Stuyck, S.; Connaulte, J.; Lesgards, G.; Prost, M.; Raffi, J.

    1998-04-01

    Ionizing radiation of vegetables is a cleaning up and preservation physical treatment which consists in submitting them to γ radiation, X radiation or electrons beam. This study deals with the influence of γ radiation on antioxidative effect of vegetables polyphenolic parts. In that purpose, we use a simple biological test based on erythrocytes haemolysis. Le traitement ionisant des produits végétaux est un procédé physique d'assainissement et de conservation qui consiste à les soumettre à l'action de rayonnements γ, de rayons X ou de faisceaux d'électrons. Ce travail porte sur l'étude de l'influence des rayonnements γ sur le pouvoir antioxydant de fractions polyphénoliques issues de substances d'origine végétale. Pour cela, un test biologique basé sur l'hémolyse d'érythrocytes est utilisé.

  2. European Code against Cancer 4th Edition: Ionising and non-ionising radiation and cancer.

    PubMed

    McColl, Neil; Auvinen, Anssi; Kesminiene, Ausrele; Espina, Carolina; Erdmann, Friederike; de Vries, Esther; Greinert, Rüdiger; Harrison, John; Schüz, Joachim

    2015-12-01

    Ionising radiation can transfer sufficient energy to ionise molecules, and this can lead to chemical changes, including DNA damage in cells. Key evidence for the carcinogenicity of ionising radiation comes from: follow-up studies of the survivors of the atomic bombings in Japan; other epidemiological studies of groups that have been exposed to radiation from medical, occupational or environmental sources; experimental animal studies; and studies of cellular responses to radiation. Considering exposure to environmental ionising radiation, inhalation of naturally occurring radon is the major source of radiation in the population - in doses orders of magnitude higher than those from nuclear power production or nuclear fallout. Indoor exposure to radon and its decay products is an important cause of lung cancer; radon may cause approximately one in ten lung cancers in Europe. Exposures to radon in buildings can be reduced via a three-step process of identifying those with potentially elevated radon levels, measuring radon levels, and reducing exposure by installation of remediation systems. In the 4th Edition of the European Code against Cancer it is therefore recommended to: "Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels". Non-ionising types of radiation (those with insufficient energy to ionise molecules) - including extremely low-frequency electric and magnetic fields as well as radiofrequency electromagnetic fields - are not an established cause of cancer and are therefore not addressed in the recommendations to reduce cancer risk. Copyright © 2015 International Agency for Research on Cancer. Published by Elsevier Ltd. All rights reserved.

  3. Current trends in estimating risk of cancer from exposure to low doses of ionising radiation.

    PubMed

    Majer, Marija; Knežević, Zeljka; Saveta, Miljanić

    2014-09-29

    Although ionising radiation has proven beneficial in the diagnosis and therapy of a number of diseases, one should keep in mind that irradiating healthy tissue may increase the risk of cancer. In order to justify an exposure to radiation, both the benefits and the risks must be evaluated and compared. The deleterious effects of medium and high doses are well known, but it is much less clear what effects arise from low doses (below 0.1 Gy), which is why such risk estimates are extremely important. This review presents the current state, important assumptions and steps being made in deriving cancer risk estimates for low dose exposures.

  4. Age at exposure to ionising radiation and cancer mortality among Hanford workers: follow up through 1994

    PubMed Central

    Wing, S; Richardson, D

    2005-01-01

    Background: Studies of workers at the plutonium production factory in Hanford, WA have led to conflicting conclusions about the role of age at exposure as a modifier of associations between ionising radiation and cancer. Aims: To evaluate the influence of age at exposure on radiation risk estimates in an updated follow up of Hanford workers. Methods: A cohort of 26 389 workers hired between 1944 and 1978 was followed through 1994 to ascertain vital status and causes of death. External radiation dose estimates were derived from personal dosimeters. Poisson regression was used to estimate associations between mortality and cumulative external radiation dose at all ages, and in specific age ranges. Results: A total of 8153 deaths were identified, 2265 of which included cancer as an underlying or contributory cause. Estimates of the excess relative risk per Sievert (ERR/Sv) for cumulative radiation doses at all ages combined were negative for all cause and leukaemia and positive for all cancer and lung cancer. Cumulative doses accrued at ages below 35, 35–44, and 45–54 showed little association with mortality. For cumulative dose accrued at ages 55 and above (10 year lag), the estimated ERR/Sv for all cancers was 3.24 (90% CI: 0.80 to 6.17), primarily due to an association with lung cancer (ERR/Sv: 9.05, 90% CI: 2.96 to 17.92). Conclusions: Associations between radiation and cancer mortality in this cohort are primarily a function of doses at older ages and deaths from lung cancer. The association of older age radiation exposures and cancer mortality is similar to observations from several other occupational studies. PMID:15961623

  5. Ionisation en couche K et effet biologique

    NASA Astrophysics Data System (ADS)

    L'Hoir, A.; Herve Du Penhoat, M. A.; Champion, C.; Fayard, B.; Touati, A.; Abel, F.; Politis, M. F.; Despiney-Bailly, I.; Sabatier, L.; Chetioui, A.

    1998-04-01

    Initial steps of radiation action mechanism on biological targets are still undnown. The strong correlation observed between inactivation cross sections by heavy ions and K-vacancy production cross sections has drawn the attention on this process. Although quite minor in the energy deposition of these particles, the K-ionization process gives rise to quite efficient ionization clusters. Values of K-ionization biological effectivenesses extracted from measured relative biological efficiencies of ultra soft X-rays support the idea of a major -may be a dominant- contribution of the K-vacancy process to the biological effect of heavy ions. Les étapes initiales des mécanismes d'effet biologique des radiations sont encore mal connues. La forte corrélation observée entre sections efficaces d'inactivation par ions lourds et sections efficaces d'ionisation K a attiré l'attention sur ce processus. Bien que de faible probabilité, l'ionisation K engendre des grappes d'ionisation très efficaces. Les valeurs de rendement létal extraites des efficacités biologiques relatives mesurées pour les rayonnements X ultra-mous suggèrent une contribution majeure -peut-être dominante- de l'ionisation K à l'effet biologique des ions.

  6. Direct estimates of cancer mortality due to low doses of ionising radiation: an international study. IARC Study Group on Cancer Risk among Nuclear Industry Workers.

    PubMed

    1994-10-15

    When setting standards for protection against ionising radiation it has been usual to extrapolate from experience with high-dose short-term exposure--studies based on atom bomb survivors and patients exposed to radiation therapeutically. Those who work in the nuclear industry are exposed to low-level predominantly gamma radiation for longer periods, and provide an alternative direct source of information. We have combined mortality data from seven cohort studies on nearly 96,000 nuclear industry workers monitored for external radiation in Canada, UK, and USA to assess directly the carcinogenic effects of protracted low-dose exposure to ionising radiation. The excess relative risk for death from leukaemia, excluding chronic lymphocytic leukaemia, was 2.2 per Sv (90% Cl 0.1 to 5.7). This estimate is intermediate between the linear estimate of 3.7 per Sv and the linear-quadratic estimate (as used in recent leukaemia risk assessments) of 1.4 per Sv derived from Japanese atomic bomb survivors' data. The excess relative risk for death from all cancers, excluding leukaemia, was -0.07 per Sv (90% Cl -0.4 to 0.3). This estimate is consistent with a range of risks varying from negative to nearly twice those estimated from atomic bomb survivors (0.18 per Sv). These are the most precise direct estimates so far made of carcinogenic risk after protracted exposure to low-dose ionising radiation. They provide little evidence that the estimates that form the basis of current radiation protection recommendations are appreciably in error.

  7. Risk of cancer from occupational exposure to ionising radiation: retrospective cohort study of workers in France, the United Kingdom, and the United States (INWORKS)

    PubMed Central

    Cardis, Elisabeth; Daniels, Robert D; Gillies, Michael; O’Hagan, Jacqueline A; Hamra, Ghassan B; Haylock, Richard; Laurier, Dominique; Leuraud, Klervi; Moissonnier, Monika; Schubauer-Berigan, Mary K; Thierry-Chef, Isabelle; Kesminiene, Ausrele

    2015-01-01

    Study question Is protracted exposure to low doses of ionising radiation associated with an increased risk of solid cancer? Methods In this cohort study, 308 297 workers in the nuclear industry from France, the United Kingdom, and the United States with detailed monitoring data for external exposure to ionising radiation were linked to death registries. Excess relative rate per Gy of radiation dose for mortality from cancer was estimated. Follow-up encompassed 8.2 million person years. Of 66 632 known deaths by the end of follow-up, 17 957 were due to solid cancers. Study answer and limitations Results suggest a linear increase in the rate of cancer with increasing radiation exposure. The average cumulative colon dose estimated among exposed workers was 20.9 mGy (median 4.1 mGy). The estimated rate of mortality from all cancers excluding leukaemia increased with cumulative dose by 48% per Gy (90% confidence interval 20% to 79%), lagged by 10 years. Similar associations were seen for mortality from all solid cancers (47% (18% to 79%)), and within each country. The estimated association over the dose range of 0-100 mGy was similar in magnitude to that obtained over the entire dose range but less precise. Smoking and occupational asbestos exposure are potential confounders; however, exclusion of deaths from lung cancer and pleural cancer did not affect the estimated association. Despite substantial efforts to characterise the performance of the radiation dosimeters used, the possibility of measurement error remains. What this study adds The study provides a direct estimate of the association between protracted low dose exposure to ionising radiation and solid cancer mortality. Although high dose rate exposures are thought to be more dangerous than low dose rate exposures, the risk per unit of radiation dose for cancer among radiation workers was similar to estimates derived from studies of Japanese atomic bomb survivors. Quantifying the cancer risks associated

  8. Risk of cancer from occupational exposure to ionising radiation: retrospective cohort study of workers in France, the United Kingdom, and the United States (INWORKS).

    PubMed

    Richardson, David B; Cardis, Elisabeth; Daniels, Robert D; Gillies, Michael; O'Hagan, Jacqueline A; Hamra, Ghassan B; Haylock, Richard; Laurier, Dominique; Leuraud, Klervi; Moissonnier, Monika; Schubauer-Berigan, Mary K; Thierry-Chef, Isabelle; Kesminiene, Ausrele

    2015-10-20

    Is protracted exposure to low doses of ionising radiation associated with an increased risk of solid cancer? In this cohort study, 308,297 workers in the nuclear industry from France, the United Kingdom, and the United States with detailed monitoring data for external exposure to ionising radiation were linked to death registries. Excess relative rate per Gy of radiation dose for mortality from cancer was estimated. Follow-up encompassed 8.2 million person years. Of 66,632 known deaths by the end of follow-up, 17,957 were due to solid cancers. Results suggest a linear increase in the rate of cancer with increasing radiation exposure. The average cumulative colon dose estimated among exposed workers was 20.9 mGy (median 4.1 mGy). The estimated rate of mortality from all cancers excluding leukaemia increased with cumulative dose by 48% per Gy (90% confidence interval 20% to 79%), lagged by 10 years. Similar associations were seen for mortality from all solid cancers (47% (18% to 79%)), and within each country. The estimated association over the dose range of 0-100 mGy was similar in magnitude to that obtained over the entire dose range but less precise. Smoking and occupational asbestos exposure are potential confounders; however, exclusion of deaths from lung cancer and pleural cancer did not affect the estimated association. Despite substantial efforts to characterise the performance of the radiation dosimeters used, the possibility of measurement error remains. The study provides a direct estimate of the association between protracted low dose exposure to ionising radiation and solid cancer mortality. Although high dose rate exposures are thought to be more dangerous than low dose rate exposures, the risk per unit of radiation dose for cancer among radiation workers was similar to estimates derived from studies of Japanese atomic bomb survivors. Quantifying the cancer risks associated with protracted radiation exposures can help strengthen the foundation for

  9. [Low dose ionising radiation and cancer: findings and methods. Report of a meeting and consequences for Switzerland].

    PubMed

    Schüler, G; Gutzwiller, F

    1991-01-01

    Today's society is concerned about the dangers of ionising radiation, especially in the aftermath of Chernobyl. On the other hand, there exists a widespread lack of understanding radiation biology and radioepidemiology--the very sciences which provide the data from which today's risk estimates have been derived. The papers in this issue of the Journal were presented at a workshop on "Low level radiation and cancer: data and methods" held on 10th-11th December in Feuisberg, near Zurich. The meeting was organised by the Institute of Social and Preventive Medicine of the University of Zurich under the auspices of the Swiss Federal Office of Public Health. Its aims were threefold. First, to give an introduction to some basic facts and methodological issues in radiation physics, biology and epidemiology. Secondly, to give an overview of the availability of data for radioepidemiological research in Switzerland and, thirdly, to evaluate possible research strategies in this country. A list of some notions and units commonly used in the radiation sciences serves an an introduction to the field (G. Schüler et al.). In using units and notions it is important to distinguish the description of biological experiments and epidemiological observations from definitions and risk projections proposed by international reports and consensus bodies for radioprotection purposes. The next papers deal more specifically with selected aspects of the basic sciences. Dosimetry means quantifying the physical effects of ionizing radiation in human tissue; this is not a straight-forward procedure (I. Cordt). The foundations of general radiation biology are succinctly summarised by C. Michel. An account of our present knowledge and theories of radiation carcinogenesis is provided by W. Burkart. W Lutz compares dose-response models of chemical carcinogenesis with those used in radiation carcinogenesis. During the last decade the epidemiological foundations of radioprotection have changed

  10. Cell culture conditions potentiate differences in the response to ionising radiation of peripheral blood leukocytes isolated from breast cancer patients and healthy subjects.

    PubMed

    Adzić, Miroslav; Nićiforović, Ana; Zarić, Bozidarka; Nesković-Konstantinović, Zora; Spasić, Snezana D; Jones, David R; Radojcić, Marija B

    2008-01-01

    To compare the effects of ionising radiation on leukocytes from breast cancer patients and healthy subjects ex vivo, the level of NF-kappaB and the antioxidant enzymes manganese-containing superoxide dismutase (Mn-SOD), copper/zinc-containing superoxide dismutase (CuZn-SOD) and catalase (CAT) in combination with flow cytometric analysis of CD4+ lymphocytes was performed. The level of Mn-SOD protein was significantly increased in the breast cancer study group both before (P < 0.001) and after (P < 0.001) irradiation when compared with healthy subjects. Measurements in parallel indicated that the level of CAT protein was significantly higher in the breast cancer study group after irradiation (2 Gy [P < 0.001] and 9 Gy [P < 0.05]) when compared with healthy subjects. Although the initial number of lymphocytes in the blood of breast cancer patients was not different from healthy subjects, the percentage of apoptotic CD4+ cells was significantly (P < 0.001) lower both before and after irradiation indicating that cell culture conditions induced radioresistance of CD4+ cells in the blood of breast cancer patients. The data presented in this current study indicate that brief ex vivo culture of peripheral blood leukocytes potentiates oxidative stress imposed by a breast cancer tumour.

  11. Identification of serum proteins discriminating colorectal cancer patients and healthy controls using surface-enhanced laser desorption ionisation-time of flight mass spectrometry

    PubMed Central

    Engwegen, Judith YMN; Helgason, Helgi H; Cats, Annemieke; Harris, Nathan; Bonfrer, Johannes MG; Schellens, Jan HM; Beijnen, Jos H

    2006-01-01

    AIM: To detect the new serum biomarkers for colorectal cancer (CRC) by serum protein profiling with surface-enhanced laser desorption ionisation - time of flight mass spectrometry (SELDI-TOF MS). METHODS: Two independent serum sample sets were analysed separately with the ProteinChip technology (set A: 40 CRC + 49 healthy controls; set B: 37 CRC + 31 healthy controls), using chips with a weak cation exchange moiety and buffer pH 5. Discriminative power of differentially expressed proteins was assessed with a classification tree algorithm. Sensitivities and specificities of the generated classification trees were obtained by blindly applying data from set A to the generated trees from set B and vice versa. CRC serum protein profiles were also compared with those from breast, ovarian, prostate, and non-small cell lung cancer. RESULTS: Mass-to-charge ratios (m/z) 3.1×103, 3.3×103, 4.5×103, 6.6×103 and 28×103 were used as classifiers in the best-performing classification trees. Tree sensitivities and specificities were between 65% and 90%. Most of these discriminative m/z values were also different in the other tumour types investigated. M/z 3.3×103, main classifier in most trees, was a doubly charged form of the 6.6×103-Da protein. The latter was identified as apolipoprotein C-I. M/z 3.1×103 was identified as an N-terminal fragment of albumin, and m/z 28×103 as apolipoprotein A-I. CONCLUSION: SELDI-TOF MS followed by classification tree pattern analysis is a suitable technique for finding new serum markers for CRC. Biomarkers can be identified and reproducibly detected in independent sample sets with high sensitivities and specificities. Although not specific for CRC, these biomarkers have a potential role in disease and treatment monitoring. PMID:16570345

  12. Electron ionisation of sulfur dioxide.

    PubMed

    Fletcher, James D; Parkes, Michael A; Price, Stephen D

    2013-05-14

    Relative precursor-specific partial ionisation cross sections for the fragment ions formed following electron ionisation of sulfur dioxide (SO2) have been measured for the first time, from 30 to 200 eV, using time-of-flight mass spectrometry coupled with two-dimensional ion coincidence detection. These data quantify the yields of O(2+), O(+), SO(2+), S(+), O2(+), and SO(+) ions, relative to the formation of SO2(+), via single, double, and triple electron ionisation of SO2. Formation of O(2+), following electron-SO2 collisions, has been quantified for the first time. The data allow a first experimental estimate of the triple ionisation potential of SO2 (69.0 ± 3.6 eV), an energy in good agreement with a value derived in this study via computational chemistry. The triple ion combination S(+) + O(+) + O(+) is clearly detected following electron collisions with SO2 at electron energies markedly below the vertical energy for forming SO2(3 +). This observation is accounted for by the operation of a stepwise pathway to the formation of S(+) + 2O(+) which does not involve the formation of a molecular trication.

  13. Ionisers in the management of bronchial asthma.

    PubMed Central

    Nogrady, S G; Furnass, S B

    1983-01-01

    Because of recent interest in the possible benefits to asthmatic patients of negative ion generators and the largely uncontrolled and inconclusive nature of earlier studies a double blind crossover study of this treatment was carried out in 20 subjects with stable asthma over six months. After an initial two week period without an ioniser, active or placebo ionisers were installed in subjects' bedrooms for two eight week periods separated by a four week "washout" period when no ioniser was present. The study was completed by a final four week period when no ioniser was present. Subjects were randomly allocated to receive an active or a placebo ioniser first. Subjects recorded their peak expiratory flow rate (PEFR) twice daily, completed a daily symptom score questionnaire, and noted any treatment they took on a diary card. Recordings were completed throughout the trial. Ion counts and dust concentrations were measured in subjects' bedrooms during the study. Mean ion counts rose considerably when ionisers were activated (p less than 0.001). There were no significant differences in PEFR, symptom score, or consumption of medication between the periods that active ionisers and either no ionisers or placebo ionisers were in operation. This study has failed to show a statistically significant benefit in asthmatic subjects from the use of negative ion generators. PMID:6364442

  14. Selective laser ionisation of radionuclide 63Ni

    NASA Astrophysics Data System (ADS)

    Tsvetkov, G. O.; D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

    2017-02-01

    We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm-1) → 3d 94d 2[7/2]4(49322.56 cm-1) → AIS(67707.61 cm-1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

  15. Enhancement of the antitumor activity of ionising radiation by nimotuzumab, a humanised monoclonal antibody to the epidermal growth factor receptor, in non-small cell lung cancer cell lines of differing epidermal growth factor receptor status

    PubMed Central

    Akashi, Y; Okamoto, I; Iwasa, T; Yoshida, T; Suzuki, M; Hatashita, E; Yamada, Y; Satoh, T; Fukuoka, M; Ono, K; Nakagawa, K

    2008-01-01

    The expression and activity of the epidermal growth factor receptor (EGFR) are determinants of radiosensitivity in several tumour types, including non-small cell lung cancer (NSCLC). However, little is known of whether genetic alterations of EGFR in NSCLC cells affect the therapeutic response to monoclonal antibodies (mAbs) to EGFR in combination with radiation. We examined the effects of nimotuzumab, a humanised mAb to EGFR, in combination with ionising radiation on human NSCLC cell lines of differing EGFR status. Flow cytometry revealed that H292 and Ma-1 cells expressed high and moderate levels of EGFR on the cell surface, respectively, whereas H460, H1299, and H1975 cells showed a low level of surface EGFR expression. Immunoblot analysis revealed that EGFR phosphorylation was inhibited by nimotuzumab in H292 and Ma-1 cells but not in H460, H1299, or H1975 cells. Nimotuzumab augmented the cytotoxic effect of radiation in H292 and Ma-1 cells in a clonogenic assay in vitro, with a dose enhancement factor of 1.5 and 1.3, respectively. It also enhanced the antitumor effect of radiation on H292 and Ma-1 cell xenografts in nude mice, with an enhancement factor of 1.3 and 4.0, respectively. Nimotuzumab did not affect the radioresponse of H460 cells in vitro or in vivo. Nimotuzumab enhanced the antitumor efficacy of radiation in certain human NSCLC cell lines in vitro and in vivo. This effect may be related to the level of EGFR expression on the cell surface rather than to EGFR mutation. PMID:18253126

  16. Serum ionised calcium concentration: measurement versus calculation.

    PubMed Central

    Conceicao, S C; Weightman, D; Smith, P A; Luno, J; Ward, M K; Kerr, D N

    1978-01-01

    Four hundred and eighteen measurements of serum ionised calcium, total calcium, and protein concentrations were made from 47 normal volunteers, 104 patients with chronic renal failure (33 being treated conservatively and 71 with regular haemodialysis), and 83 renal transplant recipients. The serum ionised calcium concentration was measured with an Orion SS-20 meter and calculated from the total serum calcium and protein concentrations by using three formulae and a nomogram. In the normal subjects and patients undergoing regular haemodialysis, whose serum calcium concentrations were in or near the normal range, three of the calculations gave results similar to those obtained by direct measurement. In patients with conservatively treated chronic renal failure and those who had received renal transplants, however, there was poor aggrement between the methods. When patients with hypercalcaemia and hypocalcaemia from all the groups were considered separately there was again poor agreement between calculated and measured concentrations of serum ionised calcium. Of the patients whose measured concentrations of serum ionised calcium were high, 69-76% were classified as normal by the four indirect methods. We conclude that calculation of the serum ionised calcium concentrations is not an adequate substitute for direct measurement. PMID:346162

  17. Tunnelling time in strong field ionisation

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Keller, Ursula

    2014-10-01

    We revisit the common approaches to tunnelling time in the context of attoclock experiments. These experiments measure tunnelling time using close-to-circularly polarised light of the infrared ultrashort laser pulse. We test the sensitivity of the attoclock measurements of tunnelling time to non-adiabatic effects, as described by a well-known theoretical model first developed by Perelomov, Popov, and Terent'ev. We find that in the case of ionisation of helium, both adiabatic and non-adiabatic theories give very similar predictions for ionisations times over a wide intensity range typical of ultrafast experiments.

  18. Background ionising radiation: a pictorial perspective.

    PubMed

    Bibbo, Giovanni; Piotto, Lino

    2014-09-01

    Ionising radiation from natural sources, known as background radiation, has existed on earth since the earth's formation. The exposure of humans and other living creatures to this radiation is a feature of the earth's environment which is continuing and inescapable. The word "radiation" brings fear to many people: a fear of the unknown, as human's senses cannot detect the presence of ionising radiation. In this study, a catalogue of images of the distribution of radioactivity in every day objects and foods has been produced using an imaging plate from a computed radiography cassette. The aim of the study is that by visually demonstrating that every day objects and foods are radioactive would alleviate the fear of "radiation" by becoming aware that we live in a radioactive environment and even our body is radioactive.

  19. Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

    PubMed Central

    Rodríguez Artalejo, F; Castaño Lara, S; de Andrés Manzano, B; García Ferruelo, M; Iglesias Martín, L; Calero, J R

    1997-01-01

    OBJECTIVES: Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. METHODS: A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. RESULTS: Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. CONCLUSIONS: Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours. PMID:9155782

  20. Occupational exposure to ionising radiation and mortality among workers of the former Spanish Nuclear Energy Board.

    PubMed

    Rodríguez Artalejo, F; Castaño Lara, S; de Andrés Manzano, B; García Ferruelo, M; Iglesias Martín, L; Calero, J R

    1997-03-01

    Firstly, to ascertain whether mortality among workers of the former Spanish Nuclear Energy Board (Junta de Energía Nuclear-JEN) was higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated with exposure to ionising radiation. A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Cohort mortality was compared with that for the Spanish population overall, with standardised mortality ratios (SMRs) adjusted for sex, age, and calendar period. Also, Poisson models were used to analyse mortality from lung cancer in the cohort by level of exposure to ionising radiation. Workers' median and mean cumulative exposures were 4.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (six deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant respiratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radiation in the dose quartiles 2, 3, and 4 versus the lowest dose quartile, were 1.00, 1.64, and 0.94, respectively. Excess mortality from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exposure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours.

  1. Medical effects and risks of exposure to ionising radiation.

    PubMed

    Mettler, Fred A

    2012-03-01

    Effects and risk from exposure to ionising radiation depend upon the absorbed dose, dose rate, quality of radiation, specifics of the tissue irradiated and other factors such as the age of the individual. Effects may be apparent almost immediately or may take decades to be manifest. Cancer is the most important stochastic effect at absorbed doses of less than 1 Gy. The risk of cancer induction varies widely across different tissues; however, the risk of fatal radiation-induced cancer for a general population following chronic exposure is about 5% Sv(-1). Quantification of cancer risk at doses of less than 0.1 Gy remains problematic. Hereditary risks from irradiation that might result in effects to offspring of humans appear to be much lower and any such potential risks can only be estimated from animal models. At high doses (over 1 Gy) cell killing and modification causes deterministic effects such as skin burns, and bone marrow depression, in which case immunosuppression becomes a critical issue. Acute whole body penetrating gamma irradiation at doses in excess of 2 Gy results in varying degrees of acute radiation sickness and doses over 10 Gy are usually lethal as a result of combined organ injury.

  2. Students' Conceptions of Ionisation Energy: A Cross-Cultural Study

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Taber, Keith S.; Liu, Xiufeng; Coll, Richard K.; Lorenzo, Mercedes; Li, Jia; Goh, Ngoh Khang; Chia, Lian Sai

    2008-01-01

    Previous studies have indicated that A-level students in the UK and Singapore have difficulty learning the topic of ionisation energy. A two-tier multiple-choice instrument developed in Singapore in an earlier study, the Ionisation Energy Diagnostic Instrument, was administered to A-level students in the UK, advanced placement high school students…

  3. Students' Conceptions of Ionisation Energy: A Cross-Cultural Study

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Taber, Keith S.; Liu, Xiufeng; Coll, Richard K.; Lorenzo, Mercedes; Li, Jia; Goh, Ngoh Khang; Chia, Lian Sai

    2008-01-01

    Previous studies have indicated that A-level students in the UK and Singapore have difficulty learning the topic of ionisation energy. A two-tier multiple-choice instrument developed in Singapore in an earlier study, the Ionisation Energy Diagnostic Instrument, was administered to A-level students in the UK, advanced placement high school students…

  4. Determination of structure parameters in molecular tunnelling ionisation model

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Ping; Zhao, Song-Feng; Zhang, Cai-Rong; Li, Wei; Zhou, Xiao-Xin

    2014-04-01

    We extracted the accurate structure parameters in a molecular tunnelling ionisation model (the so-called MO-ADK model) for 23 selected linear molecules including some inner orbitals. The molecular wave functions with the correct asymptotic behaviour are obtained by solving the time-independent Schrödinger equation with B-spline functions and molecular potentials numerically constructed using the modified Leeuwen-Baerends (LBα) model. We show that the orientation-dependent ionisation rate reflects the shape of the ionising orbitals in general. The influences of the Stark shifts of the energy levels on the orientation-dependent ionisation rates of the polar molecules are studied. We also examine the angle-dependent ionisation rates (or probabilities) based on the MO-ADK model by comparing with the molecular strong-field approximation calculations and with recent experimental measurements.

  5. Dosimetry of ionising radiation in modern radiation oncology

    NASA Astrophysics Data System (ADS)

    Kron, Tomas; Lehmann, Joerg; Greer, Peter B.

    2016-07-01

    Dosimetry of ionising radiation is a well-established and mature branch of physical sciences with many applications in medicine and biology. In particular radiotherapy relies on dosimetry for optimisation of cancer treatment and avoidance of severe toxicity for patients. Several novel developments in radiotherapy have introduced new challenges for dosimetry with small and dynamically changing radiation fields being central to many of these applications such as stereotactic ablative body radiotherapy and intensity modulated radiation therapy. There is also an increasing awareness of low doses given to structures not in the target region and the associated risk of secondary cancer induction. Here accurate dosimetry is important not only for treatment optimisation but also for the generation of data that can inform radiation protection approaches in the future. The article introduces some of the challenges and highlights the interdependence of dosimetric calculations and measurements. Dosimetric concepts are explored in the context of six application fields: reference dosimetry, small fields, low dose out of field, in vivo dosimetry, brachytherapy and auditing of radiotherapy practice. Recent developments of dosimeters that can be used for these purposes are discussed using spatial resolution and number of dimensions for measurement as sorting criteria. While dosimetry is ever evolving to address the needs of advancing applications of radiation in medicine two fundamental issues remain: the accuracy of the measurement from a scientific perspective and the importance to link the measurement to a clinically relevant question. This review aims to provide an update on both of these.

  6. Apport du rayonnement synchrotron à l'étude de cheveux archéologiques

    NASA Astrophysics Data System (ADS)

    Bertrand, L.; Chevallier, P.; Doucet, J.; Simionovici, A.; Tsoucaris, G.; Walter, P.

    2002-07-01

    La préservation dans certains contextes archéologiques des cheveux humains et des fibres animales est favorisée par leur transformation chimique au contact d'objets métalliques. Afin de mieux comprendre les phénomènes complexes mis en jeu, nous avons étudié expérimentalement la fixation de cations métalliques (Cu et Pb) dans des cheveux modèles à partir de différentes méthodes de caractérisation utilisant le rayonnement X synchrotron. Nous avons ainsi pu mettre en évidence la fixation spécifique d'une partie de ces cations au sein des lipides structurés du cheveu. La comparaison entre échantillons modèles et archéologiques apporte de nouvelles données concernant les premières étapes d'altération des cheveux archéologiques.

  7. Cosmic-ray ionisation of dense molecular clouds

    NASA Astrophysics Data System (ADS)

    Vaupre, Solenn

    2015-07-01

    Cosmic rays (CR) are of tremendous importance in the dynamical and chemical evolution of interstellar molecular clouds, where stars and planets form. CRs are likely accelerated in the shells of supernova remnants (SNR), thus molecular clouds nearby can be irradiated by intense fluxes of CRs. CR protons have two major effects on dense molecular clouds: 1) when they encounter the dense medium, high-energy protons (>280 MeV) create pions that decay into gamma-rays. This process makes SNR-molecular cloud associations intense GeV and/or TeV sources whose spectra mimic the CR spectrum. 2) at lower energies, CRs penetrate the cloud and ionise the gas, leading to the formation of molecular species characteristic of the presence of CRs, called tracers of the ionisation. Studying these tracers gives information on low-energy CRs that are unaccessible to any other observations. I studied the CR ionisation of molecular clouds next to three SNRs: W28, W51C and W44. These SNRs are known to be interacting with the nearby clouds, from the presence of shocked gas, OH masers and pion-decay induced gamma-ray emission. My work includes millimeter observations and chemical modeling of tracers of the ionisation in these dense molecular clouds. In these three regions, we determined an enhanced CR ionisation rate, supporting the hypothesis of an origin of the CRs in the SNR nearby. The evolution of the CR ionisation rate with the distance to the SNR brings valuable constraints on the propagation properties of low-energy CRs. The method used relies on observations of the molecular ions HCO+ and DCO+, which shows crucial limitations at high ionisation. Therefore, I investigated, both through modeling and observations, the chemical abundances of several other species to try and identity alternative tracers of the ionisation. In particular, in the W44 region, observations of N2H+ bring additional constraints on the physical conditions, volatile abundances in the cloud, and the ionisation

  8. Glioblastoma stem cells: radiobiological response to ionising radiations of different qualities.

    PubMed

    Pecchia, I; Dini, V; Ricci-Vitiani, L; Biffoni, M; Balduzzi, M; Fratini, E; Belli, M; Campa, A; Esposito, G; Cirrone, G; Romano, F; Stancampiano, C; Pelacchi, F; Pallini, R; Tabocchini, M A

    2015-09-01

    Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumour, with very poor prognosis. The high recurrence rate and failure of conventional treatments are expected to be related to the presence of radio-resistant cancer stem cells (CSCs) inside the tumour mass. CSCs can both self-renew and differentiate into the heterogeneous lineages of cancer cells. Recent evidence showed a higher effectiveness of C-ions and protons in inactivating CSCs, suggesting a potential advantage of Hadrontherapy compared with conventional radiotherapy for GBM treatment. To investigate the mechanisms involved in the molecular and cellular responses of CSCs to ionising radiations, two GBM stem cell (GSC) lines, named lines 1 and 83, which were derived from patients with different clinical outcomes and having different metabolic profiles (as shown by NMR spectroscopy), were irradiated with (137)Cs photons and with protons or C-ions of 62 MeV u(-1) in the dose range of 5-40 Gy. The biological effects investigated were: cell death, cell cycle progression, and DNA damage induction and repair. Preliminary results show a different response to ionising radiation between the two GSC lines for the different end points investigated. Further experiments are in progress to consolidate the data and to get more insights on the influence of radiation quality.

  9. Ionisation and the Formation of Low-Mass Protostars

    NASA Astrophysics Data System (ADS)

    Wurster, James; Bate, M. R.; Price, D. J.

    2017-06-01

    Molecular clouds are known to have strong magnetic fields and low ionisation rates. Numerical simulations performed with these more realistic conditions yield results closer to those observed, and furthermore, suggest additional observational signatures not yet explored. I will discuss my simulations of the formation of a single protostar starting from one solar mass of gas; the models include a self-consistent treatment of all three non-ideal MHD processes. My focus will be on how the ionisation parameters and non-ideal MHD processes affect the formation of the protostar and its environment.

  10. [Bipolar ionisation of indoor air through ion generators mountable into inflow ventilation and conditioning].

    PubMed

    Dudarev, A A; Spichkin, G L; Denisikhina, D M; Burtsev, S I

    2010-01-01

    Experimental studies and digital modelling of artificial indoor air ionisation through bipolar ionisers mountable into inflow ventilation and conditioning proved possible creation of continuous even bipolar ion background in indoor air, similar to the natural one.

  11. Binary-Encounter-Bethe ionisation cross sections for simulation of DNA damage by the direct effect of ionising radiation.

    PubMed

    Plante, I; Cucinotta, F A

    2015-09-01

    DNA damage is of crucial importance in the understanding of the effects of ionising radiation. To refine existing DNA damage models, an approach using the Binary-Encounter-Bethe (BEB) cross sections was developed. The differential cross sections for ionisation of the molecular orbitals of the DNA bases, sugars and phosphates are calculated using the electron binding energy, the mean kinetic energy and the occupancy number of each orbital as parameters. The resulting cross section has an analytic form which is quite convenient to use for Monte-Carlo codes that randomly sample the energy loss occurring during an ionisation event. We also describe an algorithm to simulate the interactions of electrons with DNA in the radiation transport code RITRACKS using the integrated BEB cross section for the bases, sugar and phosphates.

  12. Comparison of low and high dose ionising radiation using topological analysis of gene coexpression networks.

    PubMed

    Ray, Monika; Yunis, Reem; Chen, Xiucui; Rocke, David M

    2012-05-17

    The growing use of imaging procedures in medicine has raised concerns about exposure to low-dose ionising radiation (LDIR). While the disastrous effects of high dose ionising radiation (HDIR) is well documented, the detrimental effects of LDIR is not well understood and has been a topic of much debate. Since little is known about the effects of LDIR, various kinds of wet-lab and computational analyses are required to advance knowledge in this domain. In this paper we carry out an "upside-down pyramid" form of systems biology analysis of microarray data. We characterised the global genomic response following 10 cGy (low dose) and 100 cGy (high dose) doses of X-ray ionising radiation at four time points by analysing the topology of gene coexpression networks. This study includes a rich experimental design and state-of-the-art computational systems biology methods of analysis to study the differences in the transcriptional response of skin cells exposed to low and high doses of radiation. Using this method we found important genes that have been linked to immune response, cell survival and apoptosis. Furthermore, we also were able to identify genes such as BRCA1, ABCA1, TNFRSF1B, MLLT11 that have been associated with various types of cancers. We were also able to detect many genes known to be associated with various medical conditions. Our method of applying network topological differences can aid in identifying the differences among similar (eg: radiation effect) yet very different biological conditions (eg: different dose and time) to generate testable hypotheses. This is the first study where a network level analysis was performed across two different radiation doses at various time points, thereby illustrating changes in the cellular response over time.

  13. Comparison of low and high dose ionising radiation using topological analysis of gene coexpression networks

    PubMed Central

    2012-01-01

    Background The growing use of imaging procedures in medicine has raised concerns about exposure to low-dose ionising radiation (LDIR). While the disastrous effects of high dose ionising radiation (HDIR) is well documented, the detrimental effects of LDIR is not well understood and has been a topic of much debate. Since little is known about the effects of LDIR, various kinds of wet-lab and computational analyses are required to advance knowledge in this domain. In this paper we carry out an “upside-down pyramid” form of systems biology analysis of microarray data. We characterised the global genomic response following 10 cGy (low dose) and 100 cGy (high dose) doses of X-ray ionising radiation at four time points by analysing the topology of gene coexpression networks. This study includes a rich experimental design and state-of-the-art computational systems biology methods of analysis to study the differences in the transcriptional response of skin cells exposed to low and high doses of radiation. Results Using this method we found important genes that have been linked to immune response, cell survival and apoptosis. Furthermore, we also were able to identify genes such as BRCA1, ABCA1, TNFRSF1B, MLLT11 that have been associated with various types of cancers. We were also able to detect many genes known to be associated with various medical conditions. Conclusions Our method of applying network topological differences can aid in identifying the differences among similar (eg: radiation effect) yet very different biological conditions (eg: different dose and time) to generate testable hypotheses. This is the first study where a network level analysis was performed across two different radiation doses at various time points, thereby illustrating changes in the cellular response over time. PMID:22594378

  14. Application des codes de Monte Carlo à la radiothérapie par rayonnement à faible TEL

    NASA Astrophysics Data System (ADS)

    Marcié, S.

    1998-04-01

    In radiation therapy, there is low LET rays: photons of 60Co, photons and electrons to 4 at 25 MV created in a linac, photons 137Cs, of 192Ir and of 125I. To know the most exactly possible the dose to the tissu by this rays, software and measurements are used. With the development of the power and the capacity of computers, the application of Monte Carlo codes expand to the radiation therapy which have permitted to better determine effects of rays and spectra, to explicit parameters used in dosimetric calculation, to verify algorithms , to study measuremtents systems and phantoms, to calculate the dose in inaccessible points and to consider the utilization of new radionuclides. En Radiothérapie, il existe une variété, de rayonnements ? faible TLE : photons du cobalt 60, photons et ,électron de 4 à? 25 MV générés dans des accélérateurs linéaires, photons du césium 137, de l'iridium 192 et de l'iode 125. Pour connatre le plus exactement possible la dose délivrée aux tissus par ces rayonnements, des logiciels sont utilisés ainsi que des instruments de mesures. Avec le développement de la puissance et de la capacité, des calculateurs, l'application des codes de Monte Carlo s'est ,étendue ? la Radiothérapie ce qui a permis de mieux cerner les effets des rayonnements, déterminer les spectres, préciser les valeurs des paramètres utilisés dans les calculs dosimétriques, vérifier les algorithmes, ,étudier les systèmes de mesures et les fantomes utilisés, calculer la dose en des points inaccessibles ?à la mesure et envisager l'utilisation de nouveaux radio,éléments.

  15. Chemical profile of mango (Mangifera indica L.) using electrospray ionisation mass spectrometry (ESI-MS).

    PubMed

    Oliveira, Bruno G; Costa, Helber B; Ventura, José A; Kondratyuk, Tamara P; Barroso, Maria E S; Correia, Radigya M; Pimentel, Elisângela F; Pinto, Fernanda E; Endringer, Denise C; Romão, Wanderson

    2016-08-01

    Mangifera indica L., mango fruit, is consumed as a dietary supplement with purported health benefits; it is widely used in the food industry. Herein, the chemical profile of the Ubá mango at four distinct maturation stages was evaluated during the process of growth and maturity using negative-ion mode electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI(-)FT-ICR MS) and physicochemical characterisation analysis (total titratable acidity (TA), total soluble solids (TSS), TSS/TA ratio, and total polyphenolic content). Primary (organic acids and sugars) and secondary metabolites (polyphenolic compounds) were mostly identified in the third maturation stage, thus indicating the best stage for harvesting and consuming the fruit. In addition, the potential cancer chemoprevention of the secondary metabolites (phenolic extracts obtained from mango samples) was evaluated using the induction of quinone reductase activity, concluding that fruit polyphenols have the potential for cancer chemoprevention.

  16. Nonintrusive measurement of ionisation in vegetation fire plasma

    NASA Astrophysics Data System (ADS)

    Mphale, K. M.; Heron, M.

    2008-02-01

    Vegetation fires are slightly ionised gaseous medium. Omnipresent alkali metal species in plant's organic structure are the main source of thermally produced electrons in the fires. In the flames, electron-neutral particle collisions dominate other modes of particle interaction. The collision regime absorbs some of the incident energy when the fire is illuminated with electromagnetic waves. The rate of electromagnetic wave absorption in the vegetation fires has implications on the safety of fire-fighters. During wildfire suppression, radio communication blackout at vhf/uhf has been experienced. This may be partly due to thermal ionisation in the fire. In the experiment, the extent of ionisation in vegetation fires is measured using a 2-port vector network analyser. X-band microwaves are caused to propagate combustion zones of eucalyptus bark and guinea grass fires with maximum temperatures of 1114 and 1054 K respectively. Alkali content in the vegetation fuel was different. Measurements show maximum ionisation in flames produced from guinea grass, which had almost twice much potassium as that of eucalyptus bark, to be 2.63×1016 m-3 while that produced in eucalyptus bark flame was 1.46×1016 m-3.

  17. CAPELLA : une source de rayonnement extrême UV à 13.5 nm par décharge capillaire

    NASA Astrophysics Data System (ADS)

    Sarroukh, O.; Robert, E.; Gonthiez, T.; Thomann, A. L.; Viladrosa, R.; Fleurier, C.; Pouvesle, J. M.; Cachoncinlle, C.

    2003-06-01

    Au GREMI, nous étudions le fonctionnement d'une lampe de rayonnement Extrême Ultraviolet (EUV) émettant à 13.5nm: CAPELLA. Cette lampe consiste en une décharge capillaire dans un flux de xénon continu à basse pression. L'utilisation de Xénon à basse pression dans cette décharge permet la production de photons de faible longueur d'onde dans l'EUV. Dans cet article, nous présentons l'étude et la caractérisation de cette lampe ainsi que ses principales performances, en particulier les résultats des analyses des débris émis par la lampe pendant quelques millions de tirs.

  18. Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2006-04-30

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

  19. Ionised outflows in z ~ 2.4 quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

    2015-08-01

    Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for

  20. Ionisation of a quantum dot by electric fields

    SciTech Connect

    Eminov, P A; Gordeeva, S V

    2012-08-31

    We have derived analytical formulas for differential and total ionisation probabilities of a two-dimensional quantum dot by a constant electric field. In the adiabatic approximation, we have calculated the probability of this process in the field of a plane electromagnetic wave and in a superposition of constant and alternating electric fields. The imaginary-time method is used to obtain the momentum distribution of the ionisation probability of a bound system by an intense field generated by a superposition of parallel constant and alternating electric fields. The total probability of the process per unit time is calculated with exponential accuracy. The dependence of the results obtained on the characteristic parameters of the problem is investigated. (laser applications and other topics in quantum electronics)

  1. THE INFLUENCE OF SALTS UPON THE IONISATION OF EGG ALBUMIN

    PubMed Central

    Sørensen, S. P. L.; Linderstrøm-Lang, K.; Lund, Ellen

    1927-01-01

    Introduction. A description is given of the principle followed in the experimental determination of the ionisation of egg albumin, its capacity to combine with acids and bases. Egg albumin is regarded as an ampholyte, and in accordance with J. N. Brønsted's definition of acids and bases, ampholytes are considered as substances capable of both taking up and giving off hydrogen ions. The theoretical treatment of the capacity of ampholytes to combine with acids (and bases) has been carried out on this basis. Section A. Several experimental series are noted, comprising the determination of the activity coefficient of the hydrogen ion (fH) in ammonium chloride solutions of different concentration. Section B. The general method of experimental determination of the ionisation (capacity to combine with adds and bases) of egg albumin in ammonium chloride and potassium chloride solutions is briefly described, and the results of the experiments are compared. Section C. 1). In a brief theoretical survey we have suggested that distinction should be made between isoelectric and isoionic reaction of an ampholyte, the former defined as the hydrogen ion activity (value of paH) at which the mean valency of the ampholyte is 0, the latter as the hydrogen ion activity at which the quantity of acid or base combined with the ampholyte is 0; or, as we prefer to express it, the hydrogen ion activity at which the specific hydrogen ionisation of the ampholyte is 0. If the ampholyte does not combine with other ions than the hydrogen ion, then isoelectric and isoionic reaction coincide. Isoionic reaction is determined by acid-combining experiments. The principle of this determination is briefly described. A theoretical investigation of the alteration with salt concentration of both isoelectric (isoionic) reaction and the shape and direction of the ionisation curves is made, with regard to ampholytes capable only of combining with hydrogen ions, on the basis of the Debye-Hückel formulæ and

  2. Airborne laser-spark for ambient desorption/ionisation.

    PubMed

    Bierstedt, Andreas; Riedel, Jens

    2016-01-01

    A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die

  3. High ionisation absorption in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Bianchi, S.; Muñoz-Darias, T.; De, K.; Fender, R.; Merloni, A.

    2016-05-01

    The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and narrow absorption features, sporadically present in the X-ray spectra of some systems, are actually the signature of equatorial outflows, which might carry away more matter than that being accreted. Therefore, they play a major role in the accretion phenomenon. These outflows (or ionised atmospheres) are ubiquitous during the softer states but absent during the power-law dominated, hard states, suggesting a strong link with the state of the inner accretion disc, presence of the radio-jet and the properties of the central source. Here, we discuss the current understanding of this field.

  4. IEC STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION

    SciTech Connect

    Voytchev, Miroslav; Ambrosi, P.; Behrens, R.; Chiaro Jr, Peter John

    2011-01-01

    This paper presents IEC/SC 45B Radiation protection instrumentation and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  5. Fully kinetic simulations of magnetic reconnection in partially ionised gases

    NASA Astrophysics Data System (ADS)

    Innocenti, M. E.; Jiang, W.; Lapenta, G.; Markidis, S.

    2016-12-01

    Magnetic reconnection has been explored for decades as a way to convert magnetic energy into kinetic energy and heat and to accelerate particles in environments as different as the solar surface, planetary magnetospheres, the solar wind, accretion disks, laboratory plasmas. When studying reconnection via simulations, it is usually assumed that the plasma is fully ionised, as it is indeed the case in many of the above-mentioned cases. There are, however, exceptions, the most notable being the lower solar atmosphere. Small ionisation fractions are registered also in the warm neutral interstellar medium, in dense interstellar clouds, in protostellar and protoplanetary accreditation disks, in tokamak edge plasmas and in ad-hoc laboratory experiments [1]. We study here how magnetic reconnection is modified by the presence of a neutral background, i.e. when the majority of the gas is not ionised. The ionised plasma is simulated with the fully kinetic Particle-In-Cell (PIC) code iPic3D [2]. Collisions with the neutral background are introduced via a Monte Carlo plug-in. The standard Monte Carlo procedure [3] is employed to account for elastic, excitation and ionization electron-neutral collisions, as well as for elastic scattering and charge exchange ion-neutral collisions. Collisions with the background introduce resistivity in an otherwise collisionless plasma and modifications of the particle distribution functions: particles (and ions at a faster rate) tend to thermalise to the background. To pinpoint the consequences of this, we compare reconnection simulations with and without background. References [1] E E Lawrence et al. Physical review letters, 110(1):015001, 2013. [2] S Markidis et al. Mathematics and Computers in Simulation, 80(7):1509-1519, 2010. [3] K Nanbu. IEEE Transactions on plasma science, 28(3):971-990, 2000.

  6. IEC standards for individual monitoring of ionising radiation.

    PubMed

    Voytchev, M; Ambrosi, P; Behrens, R; Chiaro, P

    2011-03-01

    This paper presents IEC/SC 45B 'Radiation protection instrumentation' and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  7. Electrospray Ionisation Mass Spectrometry: Principles and Clinical Applications

    PubMed Central

    Ho, CS; Lam, CWK; Chan, MHM; Cheung, RCK; Law, LK; Lit, LCW; Ng, KF; Suen, MWM; Tai, HL

    2003-01-01

    This mini-review provides a general understanding of electrospray ionisation mass spectrometry (ESI-MS) which has become an increasingly important technique in the clinical laboratory for structural study or quantitative measurement of metabolites in a complex biological sample. The first part of the review explains the electrospray ionisation process, design of mass spectrometers with separation capability, characteristics of the mass spectrum, and practical considerations in quantitative analysis. The second part then focuses on some clinical applications. The capability of ESI-tandem-MS in measuring bio-molecules sharing similar molecular structures makes it particularly useful in screening for inborn errors of amino acid, fatty acid, purine, pyrimidine metabolism and diagnosis of galactosaemia and peroxisomal disorders. Electrospray ionisation is also efficient in generating cluster ions for structural elucidation of macromolecules. This has fostered a new and improved approach (vs electrophoresis) for identification and quantification of haemoglobin variants. With the understanding of glycohaemoglobin structure, an IFCC reference method for glycohaemoglobin assay has been established using ESI-MS. It represents a significant advancement for the standardisation of HbA1c in diabetic monitoring. With its other applications such as in therapeutic drug monitoring, ESI-MS will continue to exert an important influence in the future development and organisation of the clinical laboratory service. PMID:18568044

  8. Erich Regener and the ionisation maximum of the atmosphere

    NASA Astrophysics Data System (ADS)

    Carlson, P.; Watson, A. A.

    2014-12-01

    In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

  9. Threshold law for positron-atom impact ionisation

    NASA Technical Reports Server (NTRS)

    Temkin, A.

    1982-01-01

    The threshold law for ionisation of atoms by positron impact is adduced in analogy with our approach to the electron-atom ionization. It is concluded the Coulomb-dipole region of the potential gives the essential part of the interaction in both cases and leads to the same kind of result: a modulated linear law. An additional process which enters positron ionization is positronium formation in the continuum, but that will not dominate the threshold yield. The result is in sharp contrast to the positron threshold law as recently derived by Klar on the basis of a Wannier-type analysis.

  10. The influence of stopping power on the ionisation quench factor.

    PubMed

    García, G; Grau, Malonda A

    2002-01-01

    Stopping power values for high energies have been computed applying the first Born approximation and the Bethe formula. However, this approximation tends to overestimate these cross sections at low energies, reaching discrepancies on the order of 50% at energies below 1 keV for most of the molecular targets of interest. In this paper we propose a method to obtain accurate low energy stopping powers of electrons by combining total cross section measurements with a theoretical treatment of the elastic process. We determine the optimum value of the kB parameter of ionisation quenching for the stopping power obtained in this paper.

  11. Laboratory astrophysics experiments relating to ionising and weakly radiative shocks

    NASA Astrophysics Data System (ADS)

    Cross, Joseph; Foster, John; Graham, Peter; Busschaert, Clotilde; Charpentier, Nicolas; Danson, Colin; Doyle, Hugo; Drake, R. Paul; Falize, Emeric; Fyrth, Jim; Gumbrell, Edward; Koenig, Michel; Kuranz, Carolyn; Loupias, Berenice; Michaut, Claire; Patankar, Sid; Skidmore, Jonathan; Spindloe, Christopher; Tubman, Ellie; Woolsey, Nigel; Yurchak, Roman; Gregori, Gianluca

    2014-10-01

    The aim of the POLAR project is to simulate, in the laboratory, the accretion shock region of a magnetic cataclysmic variable binary star system. Scaling laws have shown that laser experiments can be related to astrophysical phenomena by matching relevant dimensionless parameters. As well as forming a reverse shock, relevant to the POLAR project, the experimental system is also likely formed of a weakly radiating shock and an ionisation front. Results from our experiment at the Orion Laser are presented here, alongside comparisons to simulation and the astrophysical case (of relevance to triggered star formation).

  12. Feedback regulated escape of ionising radiation from high redshift galaxies

    NASA Astrophysics Data System (ADS)

    Trebitsch, M.; Blaizot, J.

    2016-12-01

    Small galaxies are thought to provide the bulk of the radiation necessary to reionise the Universe by z ˜ 6. Their ionising efficiency is usually quantified by their escape fraction f_{esc}, but it is extremely hard to constrain from observations. With the goal of studying the physical processes that determine the values of the escape fraction, we have run a series of high resolution, cosmological, radiative hydrodynamics simulations centred on three galaxies. We find that the variability of the escape fraction follows that of the star formation rate, and that local feedback is necessary for radiation to escape.

  13. Intercomparison of ionisation chamber measurements from (125)I seeds.

    PubMed

    Davies, J B; Enari, K F; Baldock, C

    2007-05-01

    The reference air kerma rates of a set of individual (125)I seeds were calculated from current measurements of a calibrated re-entrant ionisation chamber. Single seeds were distributed to seven Australian brachytherapy centres for the same measurement with the user's instrumentation. Results are expressed as the ratio of the reference air kerma rate measured by the Australian Nuclear Science & Technology Organisation (ANSTO) to the reference air kerma rate measured at the centre. The intercomparison ratios of all participants were within +/-5% of unity.

  14. NICIL: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library

    NASA Astrophysics Data System (ADS)

    Wurster, James

    2016-08-01

    NICIL (Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library) calculates the ionization values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. Written as a standalone Fortran90 module that can be implemented in existing codes, NICIL is fully parameterizable, allowing the user to choose which processes to include and decide the values of the free parameters. The module includes both cosmic ray and thermal ionization; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionized.

  15. Diffusion des rayonnements X et visibles ; microscopie en champ proche : utilisation comparée pour la caractérisation des surfaces

    NASA Astrophysics Data System (ADS)

    Tollens, E.; Menecier, S.; Haidar, Y.; Zerrouki, C.; Chassevent, M.; de Fornel, F.; Bonnet, J. J.

    2004-11-01

    Trois méthodes ont été utilisées pour caractériser la rugosité de quelques échantillons. Deux de ces méthodes sont basées sur la mesure du rayonnement diffusé (visible et X). La troisième utilise la microscopie en champ proche (MCP). Dans un premier temps, une comparaison des deux premières techniques a été menée en utilisant une même théorie vectorielle de la diffusion. Bien adaptée au domaine du visible, cette théorie peut aussi être utilisée dans le cas du rayonnement X. Les densités spectrales de puissance (dsp) de la rugosité, déterminées expérimentalement pour deux échantillons d'Alacrite XSH (alliage quaternaire à base de cobalt utilisé en métrologie des masses), montrent des allures identiques dans le cas du visible et du rayonnement X à des incidences très rasantes. Dans un deuxième temps, la hauteur quadratique moyenne δ , caractéristique de la rugosité de ces deux échantillons, a été déterminée de façon "directe" par microscopie en champ proche, et à partir des dsp pour les deux autres techniques. La restriction à une bande commune des fréquences spatiales accessibles à ces techniques, conduit à des valeurs de δ comparables aux incertitudes près. Une validation des mesures X ainsi faite, un accent est mis sur leur apport complémentaire par rapport au visible.

  16. Partial ionisation cross-sections of 2-propanol and ethanal

    NASA Astrophysics Data System (ADS)

    Vacher, J. R.; Jorand, F.; Blin-Simiand, N.; Pasquiers, S.

    2006-04-01

    Electron impact ionisation of 2-propanol and ethanal is studied using mass spectrometry. Cross-sections of the formation of molecular ions and ionic fragments are measured between 14 and 86 eV. Free energy changes are evaluated using ab initio calculations. For 2-propanol, two ions, identified as CH 3CHOH + (45 amu) and CH3CHCH3+ (43 amu), contribute more than 75% to the total cross-section over the whole range of electron energies and are produced by simple bond cleavage in the molecular ion. Both processes occur spontaneously, leaving the molecular ion as a minority species. For ethanal, two ions, identified as HCO + (29 amu) and CH 3CO + (43 amu), and the molecular ion (44 amu) contribute more than 80% to the total cross-section. The ions of 29 and 43 amu result from a simple bond cleavage in the molecular ion. These sprocesses are not spontaneous and the contribution of the molecular ion becomes predominant at 15 eV and is therefore significant over the whole range of ionisation energies.

  17. On-line reaction monitoring by extractive electrospray ionisation.

    PubMed

    McCullough, Bryan J; Bristow, Tony; O'Connor, Gavin; Hopley, Chris

    2011-05-30

    The design and development of a novel extractive electrospray ionisation (EESI) device for on-line reaction monitoring is described. The EESI apparatus uses a secondary, grounded nebuliser to produce an analyte aerosol and a Venturi pump is then used to transfer a sample of the aerosol to an electrospray source where it is ionised. The EESI apparatus was then tested with a variety of small, organic molecules to assess sensitivity, linearity and dynamic range. The performance of the technique will depend on the mass spectrometer used for the experiments; in the configurations used here it has a usable dynamic range of around 3.5 orders of magnitude with a linear range of around 2.5 orders of magnitude and is capable of analysing species present down to low µg/mL with signal-to-noise ratio greater than 2.5. The use of EESI for reaction monitoring was validated using a series of mock reaction mixtures and then used to monitor the base hydrolysis of ethyl salicylate to salicylic acid. Copyright © 2011 John Wiley & Sons, Ltd.

  18. Kr-81m calibration factor for the npl ionisation chamber.

    PubMed

    Johansson, Lena; Stroak, Andrew

    2006-01-01

    A general method has been developed for the measurement of the activity concentration of 81mKr gas. Due to its short half-life, 13.1s, this gas has to be eluted from a 81Rb/81mKr generator. The 81Rb parent has a half-life of about 4.6 h. The calibration was done in two steps: firstly, a gamma-ray spectrometer was calibrated using 51Cr and 139Ce sources, nuclides with gamma-ray energies bracketing that of 81mKr (190.5 keV). The measurement geometry was equivalent to that of the 81mKr measurement; the sources were inserted into two collimated PTFE tubes in front of the gamma-ray detector. Secondly, a calibration factor for the NPL radionuclide calibrator was determined with a specially designed ionisation chamber insert. The 81mKr gas passed in front of the gamma-ray detector in PTFE tubing before and after entering the ionisation chamber. The calibration factor for 81mKr in the radionuclide calibrator with this geometry was independent of the gas flow rate within determined limits. The analytical calculations of the activity determination, uncertainties and measurement criteria are discussed.

  19. A low background ionisation chamber for alpha-spectroscopy

    NASA Astrophysics Data System (ADS)

    Wilsenach, Heinrich; Zuber, Kai; Krüger, Felix; Hartmann, Andreas; Sobiella, Manfred

    2017-09-01

    The goal of designing a low background ionisation chamber is to measure long lived α-decay half-lives which might interfere with rare event searches. Such decays play a part in many fields in nuclear physics and are difficult to measure. A lot of Geiger-Nutall studies also depend on them. Among others the research is specifically aimed at the precision measurements of α emitters mainly within the Lanthanide region. The excellent energy resolution would also allow to search for excited states in α-decays. To achieve this goal a gridded ionisation chamber was constructed using the Frisch-Grid design. A background rate of only 10.9(6) counts per day has been achieved in the energy region of 1 MeV to 9 MeV and improvements are possible. This low background rate and size of the chamber allows precision measurements of long living alpha decays with half-lives in the region of 1 × 1015 years.

  20. Transferring calibration coefficients from ionisation chambers used for diagnostic radiology to transmission chambers.

    PubMed

    Yoshizumi, Maíra T; Caldas, Linda V E

    2012-07-01

    In this work, the response of a double volume transmission ionisation chamber, developed at the Instituto de Pesquisas Energéticas e Nucleares, was compared to that of a commercial transmission chamber. Both ionisation chambers were tested in different X-ray beam qualities using secondary standard ionisation chambers as reference dosimeters. These standard ionisation chambers were a parallel-plate and a cylindrical ionisation chambers, used for diagnostic radiology and mammography beam qualities, respectively. The response of both transmission chambers was compared to that of the secondary standard chambers to obtain coefficients of equivalence. These coefficients allow the transmission chambers to be used as reference equipment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Specification of the quality of ionising radiations for unified dosimetry in radiobiology and radiological protection

    NASA Astrophysics Data System (ADS)

    Alkharam, Ali Salem

    It is widely agreed in radiobiological and biophysical research that the DNA is the dominant target which can lead to terminal biological damage in the form of cancer or cell death. A main objective in radiation protection is to set the limits of the possible harmful effects to the general population exposed to ionising radiation at low level (environmental level). The initial slope of the dose-response curve is found to be an appropriate parameter to achieve this objective. Bench mark data sets of the initial effects of ionising radiation on cells in vitro were formed which include both physical characterisation of the radiation and the radiobiological parameters. These data-bases include the mammalian cell end-points: cellular inactivation, chromosome dicentrics, HPRT mutations and oncogenic transformations. On the molecular scale, the databases include single-strand and double strand breaks induced in the DNA of both mammalian and non-mammalian cells. Analysis of bio-effect mechanisms of damage to mammalian cells in terms of the quality parameter 'mean free path for linear primary ionisation' for ionising radiation, strongly suggest that there is a common mechanism for the biological endpoints of dicentrics, mutations, and oncogemc transformations. A unified response is obtained for all types of heavy ions and all cells which show: a common inflection point at inter-spacing distance equivalent to lambda0 = 1.4+/- 0.5 nm, a saturation region at lambda < lambda0 and almost constant slope for lambda < lambda0. The lethal lesions are identified as dsb's in the intracellular DNA. It follows that radiation risk factors can be determined on the basis of simple ratios to the inactivation cross sections. The size of these genes are found to be in close proximity to the optimised saturation levels. The probabilities of risk with respect to inactivation, for chromosome dicentrics, oncogenic transformations, and mutations of the HPRT gene are respectively 0.18, 1.6 x 10

  2. Hazards of ionising radiation: 100 years of observations on man.

    PubMed Central

    Doll, R.

    1995-01-01

    In November 1895, when Conrad Röntgen serendipitously discovered X-rays, epidemiology was effectively limited to the study of infectious disease. What little epidemiological work was done in other fields was done as part of clinical medicine or under the heading of geographical pathology. The risks from exposure to X-rays and subsequently from other types of ionising radiation were consequently discovered by qualitative association or animal experiment. They did not begin to be quantified in humans until half a century later, when epidemiology emerged as a scientific discipline capable of quantifying risks of non-infectious disease and the scientific world was alerted to the need for assessing the effects of the radiation to which large populations might be exposed by the use of nuclear energy in peace and war. PMID:8519643

  3. Review of retrospective dosimetry techniques for external ionising radiation exposures.

    PubMed

    Ainsbury, E A; Bakhanova, E; Barquinero, J F; Brai, M; Chumak, V; Correcher, V; Darroudi, F; Fattibene, P; Gruel, G; Guclu, I; Horn, S; Jaworska, A; Kulka, U; Lindholm, C; Lloyd, D; Longo, A; Marrale, M; Monteiro Gil, O; Oestreicher, U; Pajic, J; Rakic, B; Romm, H; Trompier, F; Veronese, I; Voisin, P; Vral, A; Whitehouse, C A; Wieser, A; Woda, C; Wojcik, A; Rothkamm, K

    2011-11-01

    The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements.

  4. Protection of the environment from ionising radiation: ethical issues.

    PubMed

    Oughton, Deborah

    2003-01-01

    The paper identifies some of the main ethical issues concerning the protection of the environment from radiation and suggests ways in which ethics can aid in developing a system of protection. After a presentation of background on ethical theory and environmental ethics, three main issues related to environmental protection are discussed: First, the question of valuing the environment and implications for the definition of harm and monetary valuation of environmental goods; second, difficulties with scientific uncertainty and applications of the precautionary principle; and third, issues concerned with the distribution of risk and its relevance for participation in decision-making. In summary, the paper argues that there are strong ethical grounds to provide for the protection of the environment and that, all other things being equal, there is no reason to treat ionising radiation differently to other environmental stressors. Copyright 2002 Elsevier Science Ltd.

  5. Migration levels of PVC plasticisers: Effect of ionising radiation treatment.

    PubMed

    Zygoura, Panagiota D; Paleologos, Evangelos K; Kontominas, Michael G

    2011-09-01

    Migration levels of commercial plasticisers [di-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)] from polyvinyl chloride (PVC) film into the EU specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10days (EEC, 1993). Determination of the analytes was performed by applying the analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection (GC-FID) recently proposed by our group. The study focuses on the determination of the effect of gamma radiation on plasticiser migration into the selected simulants. PVC cling film used was subjected to ionising treatment with a [(60)Co] source at doses equal to 5, 15 and 25kGy. DEHA and ATBC migration into the EU aqueous simulating solvents was limited, yielding final concentrations in the respective ranges 10-100μg/l and 171-422μg/l; hence, ATBC demonstrated a stronger interaction with all three simulants compared to DEHA. Migration data, with respect to ATBC, showed that the most aggressive simulant seemed to be the 10% ethanol, while in the case of DEHA the 3% aqueous acetic acid exhibited the highest extraction efficiency; distilled water demonstrated the lowest migration in both cases. With regard to PVC treatment with gamma rays, high radiation doses up to 25kGy produced a statistically significant (p<0.05) effect on the migration of both plasticisers.

  6. Electron impact ionisation cross sections of iron hydrogen clusters

    NASA Astrophysics Data System (ADS)

    Huber, Stefan E.; Sukuba, Ivan; Urban, Jan; Limtrakul, Jumras; Probst, Michael

    2016-09-01

    We computed electron impact ionisation cross sections (EICSs) of iron hydrogen clusters, FeH n with n = 1,2, ...,10, from the ionisation threshold to 10 keV using the Deutsch-Märk (DM) and the binary-encounter-Bethe (BEB) formalisms. The maxima of the cross sections for the iron hydrogen clusters range from 6.13 × 10-16 cm2 at 60 eV to 8.76 × 10-16 cm2 at 76 eV for BEB-AE (BEB method based on quantum-chemical data from all-electron basis sets) calculations, from 4.15 × 10-16 cm2 at 77 eV to 7.61 × 10-16 cm2 at 80 eV for BEB-ECP (BEB method based on quantum-chemical data from effective-core potentials for inner-core electrons) calculations and from 2.49 × 10-16 cm2 at 43.5 eV to 7.04 × 10-16 cm2 at 51 eV for the DM method. Cross sections calculated via the BEB method are substantially higher than the ones obtained via the DM method, up to a factor of about two for FeH and FeH2. The formation of Fe-H bonds depopulates the iron 4 s orbital, causing significantly lower cross sections for the small iron hydrides compared to atomic iron. Both the DM and BEB cross sections can be fitted perfectly against a simple expression used in modelling and simulation codes in the framework of nuclear fusion research. The energetics of the iron hydrogen clusters change substantially when exact exchange is present in the density functional, while the cluster geometries do not depend on this choice.

  7. Ionisation Equilibrium for the Non-Maxwellian Electron n-Distributions in Solar Flares: Updated Calculations

    NASA Astrophysics Data System (ADS)

    Dzifčáková, Elena; Dudík, Jaroslav

    2015-12-01

    We use the latest available atomic data to calculate the ionisation and recombination rates for the non-Maxwellian n-distributions, which were shown previously to provide a good fit to the enhanced intensities of dielectronic satellite lines during solar flares. The ionisation and recombination coefficients are subsequently used to derive the ionisation equilibrium. To do so, we consider odd values of n ranging from 1 to 19, i.e., from Maxwellian to strongly non-Maxwellian cases. These calculations involve all elements with proton number up to 30, i.e., H to Zn. The n-distributions modify both the ionisation and the recombination rates. The ionisation rates decrease more steeply at lower pseudo-temperatures, while the radiative recombination rate is reduced due to a lower number of low-energy electrons. The peaks of the dielectronic recombination rates become narrower. These changes are reflected in the ionisation equilibrium. Ion abundance peaks become narrower and can also be shifted, mostly towards higher temperatures. The He-like ions are an important exception, as they are formed in a larger temperature range than that for the Maxwellian distribution. The ions Si xiii - xiv used previously for the diagnostics of the n-distributions are affected only weakly, confirming the determination of n. The ionisation equilibria are available as the electronic supplementary material in a format compatible with the CHIANTI database.

  8. INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    NASA Astrophysics Data System (ADS)

    Kosarev, N. I.; Shaparev, N. Ya

    2006-04-01

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo.

  9. Ionising sources in the coma of 67P probed by Rosetta

    NASA Astrophysics Data System (ADS)

    Heritier, Kevin; Galand, Marina; Henri, Pierre; Eriksson, Anders; Odelstad, Elias; Altwegg, Kathrin; Beth, Arnaud; Broiles, Thomas; Burch, Jim; Carr, Christopher; Cupido, Emanuele; Glassmeier, Karl-Heinz; Nilsson, Hans; Richter, Ingo; Rubin, Martin; Vallieres, Xavier; Vigren, Erik

    2017-04-01

    An ionospheric model has been developed in order to quantify the ion number density in the coma of 67P/Churyumov-Gerasimenko. The model is driven by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Cometary Pressure Sensor (COPS) neutral density and assumes isentropic expansion for the neutral density profile. The two ionisation sources considered are photo-ionisation by solar extreme ultraviolet (EUV) radiation and electron-impact ionisation. The EUV radiation is estimated from fluxes measured by the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED)/ Solar EUV Experiment (SEE), taking into account the phase shift and the heliocentric distance ratio; between Earth and comet 67P. The electron-impact ionisation production rates are derived from Rosetta Plasma Consortium (RPC)-Ion and Electron Sensor (IES) integrated electron fluxes and corrected for the S/C potential from RPC/LAngmuir Probe (LAP) measurements. Our results are compared with in situ measurements of the plasma density from RPC-Mutual Impedance Probe (MIP) and RPC-LAP. There is a good agreement between the modelled and RPC observed electron densities. The ionospheric model enables to distinguish the relative contributions of the different sources to the total cometary plasma. At high heliocentric distances, electron-impact ionisation becomes the dominant ionisation source and is enhanced over the winter hemisphere. As the solar activity has decreased since the beginning of the mission in 2014, the relative importance of photo-ionisation has decreased as well. However, at low heliocentric distances, photo-ionisation seems to be the most dominant ionising source, in particular through the perihelion period in summer 2015.

  10. Photo-ionisation mass spectrometry as detection method for gas chromatography. Optical selectivity and multidimensional comprehensive separations.

    PubMed

    Zimmermann, Ralf; Welthagen, Werner; Gröger, Thomas

    2008-03-14

    Mass spectrometry (MS) with soft ionisation techniques (i.e. ionisation without fragmentation of the analyte molecules) for gaseous samples exhibits interesting analytical properties for direct analysis applications (i.e. direct inlet mass spectrometric on-line monitoring) as well as mass spectrometric detection method for gas chromatography (GC-MS). Commonly either chemical ionisation (CI) or field ionisation (FI) is applied as soft ionisation technology for GC-MS. An interesting alternative to the CI and FI technologies methods are photo-ionisation (PI) methods. PI overcomes some of the limitations of CI and FI and furthermore add some unique analytical properties. The resonance enhanced multi-photon ionisation (REMPI) method uses intense UV-laser pulses (wavelength range approximately 350-193 nm) for highly selective, sensitive and soft ionisation of predominately aromatic compounds. The single photon ionisation (SPI) method utilises VUV light (from lamps or laser sources, wavelengths range approximately 150-110 nm) can be used for a universal soft ionisation of organic molecules. In this article the historical development as well as the current status and concepts of gas chromatography hyphenated to photo-ionisation mass spectrometry are reviewed.

  11. Differential ionisation of natural antioxidant polyenes in electrospray and nanospray mass spectrometry.

    PubMed

    Guaratini, Thais; Gates, Paul J; Pinto, Ernani; Colepicolo, Pio; Lopes, Norberto P

    2007-01-01

    Carotenoids are natural products with high economic relevance for the pharmaceutical industries and are a common subject for biochemical research. Reported here is a comparative study of the ionisation of carotenoids by electrospray mass spectrometry (ESI-MS) and nanospray mass spectrometry (nanoESI-MS). The results demonstrate that, along with solvent choice, the influence of the different ionisation processes of ESI and nanoESI are fundamental in determining how ionisation is achieved and which ions (molecular ion or protonated molecule) are observed in MS. The increased understanding afforded by this study will help in the development of unequivocal microanalytical methods for carotenoids and related antioxidant polyenes.

  12. Predictive value of derived calcium figures based on the measurement of ionised calcium.

    PubMed

    Gardner, M D; Dryburgh, F J; Fyffe, J A; Jenkins, A S

    1981-03-01

    The algorithms used in this hospital to assess calcium status are calculated ionised serum calcium and the serum calcium concentration adjusted for albumin. In order to establish their clinical usefulness, they were compared with the ionised calcium concentration measured on the Nova 2 instrument in patients with various calcium and protein abnormalities. Good correlation was found between the measured and calculated values. The predictive values for the calculated results and for total serum calcium concentrations are presented. In this series, the derived values were useful in predicting the serum ionised calcium concentration of the patients studied.

  13. Ionisation effect on the electron localisation in the subcycle waveform shaping scheme

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Feng, Zhengpeng; Long, Hua

    2015-03-01

    We have theoretically studied the ionisation effect on the asymmetric dissociation of H+2 exposed to the synthesised multicycle infrared pulses of different wavelengths by solving the time-dependent Schr?dinger equation without using the Born-Oppenheimer approximation. It has been demonstrated that the ionisation does slightly influence the electron localisation for the relatively low pulse intensity (less than 1014 W/cm2). However, our further results show that the ionisation effect becomes much more significant when increasing the pulse intensity, leading to a distinctly different mechanism responsible for the enhancement of the electron localisation.

  14. Ionisation Mechanisms in AN Optically Pumped Mercury Vapour.

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.

    Available from UMI in association with The British Library. Requires signed TDF. A plasma formed in a mercury vapour by optical pumping at visible and U.V. wavelengths from a high current mercury discharge, has been investigated with a view to gaining an understanding of the ionisation processes giving rise to the plasma. These were believed to generate both atomic and molecular ions. The results of this work have applications in the fields of fluorescent lighting and the mercury-nitrogen laser. The plasma was studied with a variety of diagnostic tools. Electron number densities and temperatures were determined using Langmuir probes operating in the orbital motion limited regime. Populations of the 6^3 P triplet states, believed to be the only significantly populated excited states in the plasma, were determined using absorption spectroscopy. Lastly, a quadrupole mass spectrometer, coupled to the plasma with an electrostatic ion transport system, was used to investigate the flux of atomic and molecular ions to a body at floating potential in the plasma. The Langmuir probe and absorption spectroscopy results were included into a model describing ion motions in the plasma, based around the ion fluid equations and including source terms for the generation of atomic and molecular ions, both by electron impact and by binary collisions of atoms in the 6^3P triplet states. Where possible, ionisation rats in the model were calculated using published cross-sections. However, for the heavy body collisional processes in particular, many of these are unknown. Consequently, an attempt was made to determine these cross-sections by generating results from the model that could be compared to experimental measurements of the atomic and molecular ion fluxes to the mass spectrometer. A number of computational experiments were carried out, varying the cross-sections until a good fit to the experimental measurements was achieved. Using this technique it was possible to estimate cross

  15. Ionisation Chambers and Secondary Emission Monitors at the PROSCAN Beam Lines

    NASA Astrophysics Data System (ADS)

    Dölling, Rudolf

    2006-11-01

    PROSCAN, the dedicated new medical facility at PSI using proton beams for the treatment of deep seated tumours and eye melanoma, is now in the commissioning phase. Air filled ionisation chambers in several configurations are used as current monitors, profile monitors, halo, position and loss monitors at the PROSCAN beam lines. Similar monitors based on secondary emission are used for profile and current measurements in the regime where saturation deteriorates the accuracy of the ionisation chambers.

  16. ER stress induced by ionising radiation in IEC-6 cells.

    PubMed

    Zhang, Bo; Wang, Yan; Pang, Xueli; Su, Yongping; Ai, Guoping; Wang, Tao

    2010-06-01

    Ionising radiation (IR) can evoke a series of biochemical events inside the cell. However, whether IR can directly induce endoplasmic reticulum (ER) stress is not clear. In our previous study, we found that there might be a causative link between IR and ER stress. In this study, we further characterised the type of ER stress induced by IR. Rat intestinal epithelial cells IEC-6 were irradiated at a dose of 10 Gy, and total RNA and proteins were harvested at indicated time points. The mRNA and protein expression of immunoglobulin heavy chain binding protein (BiP) and glucose regulated protein 94 (GRP94) was detected along with proteins associated with ER stress signal pathways. Our results indicated that IR induced up-regulation of ER stress marker including BiP and GRP94 at protein and mRNA levels in IEC-6 cells. Increased phosphorylation of eukaryotic translation initiation factor 2 (eIF2alpha) and induced mRNA splicing of X-box binding protein 1 (XBP1) suggested that PERK (interferon-induced double-stranded RNA-activated protein kinase (PRKR) -like endoplasmic reticulum kinase) and IRE1 (inositol requirement 1) signal transduction pathways were involved in this kind of ER stress. However, the active form of activating transcription factor 6 (ATF6) did not change significantly in irradiated cells, which suggested that the ATF6 pathway was not involved. Thus, we concluded that IR could induce moderate ER stress directly in IEC-6 cells.

  17. Excitation and Ionisation dynamics in high-frequency plasmas

    NASA Astrophysics Data System (ADS)

    O'Connell, D.

    2008-07-01

    Non-thermal low temperature plasmas are widely used for technological applications. Increased demands on plasma technology have resulted in the development of various discharge concepts based on different power coupling mechanisms. Despite this, power dissipation mechanisms in these discharges are not yet fully understood. Of particular interest are low pressure radio-frequency (rf) discharges. The limited understanding of these discharges is predominantly due to the complexity of the underlying mechanisms and difficult diagnostic access to important parameters. Optical measurements are a powerful diagnostic tool offering high spatial and temporal resolution. Optical emission spectroscopy (OES) provides non-intrusive access, to the physics of the plasma, with comparatively simple experimental requirements. Improved advances in technology and modern diagnostics now allow deeper insight into fundamental mechanisms. In low pressure rf discharges insight into the electron dynamics within the rf cycle can yield vital information. This requires high temporal resolution on a nano-second time scale. The optical emission from rf discharges exhibits temporal variations within the rf cycle. These variations are particularly strong, in for example capacitively coupled plasmas (CCPs), but also easily observable in inductively coupled plasmas (ICPs), and can be exploited for insight into power dissipation. Interesting kinetic and non-linear coupling effects are revealed in capacitive systems. The electron dynamics exhibits a complex spatio-temporal structure. Excitation and ionisation, and, therefore, plasma sustainment is dominated through directed energetic electrons created through the dynamics of the plasma boundary sheath. In the relatively simple case of an asymmetric capacitively coupled rf plasma the complexity of the power dissipation is exposed and various mode transitions can be clearly observed and investigated. At higher pressure secondary electrons dominate the

  18. Simultaneous radar and video meteors—II: Photometry and ionisation

    NASA Astrophysics Data System (ADS)

    Weryk, Robert J.; Brown, Peter G.

    2013-06-01

    Simultaneous radar and video measurements of meteors were made using the Canadian Meteor Orbit Radar (CMOR) and several Gen-III image-intensified CCD cameras primarily to relate radar meteor electron line density, q, to video meteor photon radiant power, I. We find that log10q=log10I+(12.56±0.49) leading to M=(38.7±1.2)-2.5log10q, where M is the meteor magnitude in the Gen-III video bandpass (470-850 nm) corresponding to q at the radar specular point. The ratio of the ionisation coefficient to luminous efficiency, β/τI, was estimated from our observations of q/I to functionally depend on speed and radiant power. For our average meteor photon radiant power of I=64W, we find log10β/τI=(3.00±0.62)log10v-(4.27±1.37). By adopting β computed according to Jones (1997), which we approximate as log10β=5.84-0.09v0.5-9.56/log10v (roughly proportional to v4 between 20 and 40 km/s), a corresponding estimate of τI for our intensified spectral bandpass was made using our measurements of q/I. We find a peak bolometric value of τI=5.9% at 41 km/s. The main uncertainties associated with our analysis are the unknown spectra of individual meteors which affect our estimate of absolute radiant power, and uncertain values of the initial trail radius which makes estimates of q problematic. Our results suggest that the video meteor mass scale is an order of magnitude smaller than previously thought at these higher speeds, and implies that the total meteoroid mass influx between 10-5 and 10-8kg is lower than previous studies would suggest.

  19. Development of a new ionisation chamber, for HP(10) measurement, using Monte-Carlo simulation and experimental methods.

    PubMed

    Silva, H; Cardoso, J; Oliveira, C

    2011-03-01

    An ionisation chamber that directly measures the quantity personal dose equivalent, H(p)(10), is used as a secondary standard in some metrology laboratories. An ionisation chamber of this type was first developed by Ankerhold. Using the Monte-Carlo simulation, the dose in the sensitive volume as a function of the IC dimensions and the effects of the several components of the ionising chamber have been investigated. Based on these results, a new ionising chamber, lighter than the previous ones, is constructed and experimentally tested.

  20. Surface ionisation of molecular H2 and atomic H Rydberg states at doped silicon surfaces

    NASA Astrophysics Data System (ADS)

    Sashikesh, G.; So, E.; Ford, M. S.; Softley, T. P.

    2014-09-01

    The detection of ions or electrons from the surface ionisation of molecular H2 and atomic H Rydberg states incident at doped Si surfaces is investigated experimentally to analyse the effect of the dopant charge distribution on the surface-ionisation processes. In both experimental studies, the molecular H2 and atomic H Rydberg states are generated via two-colour vacuum ultraviolet--ultraviolet (VUV-UV) resonant excitation. For H2, various Stark states of the N+ = 2, n = 17 manifold are populated in the presence of an electric field. The variation of the observed surface-ionisation signal with surface dopant concentration and type, shows similar characteristics for all the Stark states. A comparison is made between these ion-detected surface-ionisation profiles and those obtained via electron detection. Different trends as a function of dopant concentration and type are observed for the two cases, explained by the greater effect of surface charges on the post-ionisation ion trajectory compared to the electron trajectory. For the atomic-H Rydberg states with principal quantum number ? populated in the absence of a Stark field, the observed behaviour is similar to the interaction of molecular H2 Rydberg states at the same surfaces, and these measurements confirm that the observed effects are attributable to the nature of the target surface rather than the specific atomic or molecular Rydberg species.

  1. Total ionisation cross sections for chlorofluoromethanes and CClx radicals by electron impact

    NASA Astrophysics Data System (ADS)

    Gupta, Dhanoj; Antony, Bobby

    2014-07-01

    We report here the total ionisation cross section for chlorofluoromethanes, namely CCl3F (Freon 11), CCl2F2 (Freon 12), CClF3 (Freon 13), CHCl2F (Freon 21), CHClF2 (Freon 22), CH2ClF (Freon 31), CCl4 and CClx (x = 1-3), radicals by electron impact from ionisation threshold to 2 keV. The total inelastic cross section is obtained employing a complex optical potential formalism and solving the Schrödinger equation through partial wave analysis. Using the complex scattering potential-ionisation contribution method, the total ionisation cross section is derived from the inelastic cross section for these targets. The results obtained are then compared with the existing experimental and theoretical data, wherever available. The present result shows reasonable agreement with previous data. For the CClx radicals, the ionisation cross section is predicted for the first time. The data reported here have immense interest to atmospheric and technological plasma modelling.

  2. Ionising irradiation alters the dynamics of human long interspersed nuclear elements 1 (LINE1) retrotransposon.

    PubMed

    Tanaka, Atsushi; Nakatani, Youko; Hamada, Nobuyuki; Jinno-Oue, Atsushi; Shimizu, Nobuaki; Wada, Seiichi; Funayama, Tomoo; Mori, Takahisa; Islam, Salequl; Hoque, Sheikh Ariful; Shinagawa, Masahiko; Ohtsuki, Takahiro; Kobayashi, Yasuhiko; Hoshino, Hiroo

    2012-09-01

    It is important to identify the mechanism by which ionising irradiation induces various genomic alterations in the progeny of surviving cells. Ionising irradiation activates mobile elements like retrotransposons, although the mechanism of its phenomena consisting of transcriptions and insertions of the products into new sites of the genome remains unclear. In this study, we analysed the effects of sparsely ionising X-rays and densely ionising carbon-ion beams on the activities of a family of active retrotransposons, long interspersed nuclear elements 1 (L1). We used the L1/reporter knock-in human glioma cell line, NP-2/L1RP-enhanced GFP (EGFP), that harbours full-length L1 tagged with EGFP retrotransposition detection cassette (L1RP-EGFP) in the chromosomal DNA. X-rays and carbon-ion beams similarly increased frequencies the transcription from L1RP-EGFP and its retrotransposition. Short-sized de novo L1RP-EGFP insertions with 5'-truncation were induced by X-rays, while full-length or long-sized insertions (>5 kb, containing ORF1 and ORF2) were found only in cell clones irradiated by the carbon-ion beams. These data suggest that X-rays and carbon-ion beams induce different length of de novo L1 insertions, respectively. Our findings thus highlight the necessity to investigate the mechanisms of mutations caused by transposable elements by ionising irradiation.

  3. Multicolour FISH analysis of ionising radiation induced micronucleus formation in human lymphocytes

    PubMed Central

    Balajee, Adayabalam S.; Bertucci, Antonella; Taveras, Maria; Brenner, David J.

    2014-01-01

    Micronucleation of chromosomal DNA is an effective indicator of DNA damage and micronucleus (MN) analysis is a valuable tool for radiation biodosimetry studies. To gain a comprehensive knowledge of micronucleation process after ionising radiation (IR) exposure, whole genome-wide chromosome analysis is desirable. With this objective, multicolour fluorescence in situ hybridization (M-FISH) technique was utilised in the present study to characterise the chromosome content of spontaneous and IR-induced micronuclei in three human donors. M-FISH analysis revealed a radiation dose-dependant increase in the number of micronuclei with multi-chromosome material above 2 Gy and as many as 3–6 multicolour signals were detected in micronuclei after high γ-rays radiation doses (5–10 Gy). Involvement of each human chromosome material was more frequently detected in multicoloured micronuclei than in single-coloured micronuclei at high radiation doses (>2 Gy). Observation of dose-dependant increase in the MN frequency with multi-chromosome material may be due to misrepair of DNA double-strand breaks involving multiple chromosomes leading to asymmetric dicentric or ring chromosomes and acentric fragments. Chromosomes belonging to groups A (1, 2 and 3) and B (4 and 5) were frequently detected in 35–45% of the total micronuclei either as single entities or in combination with other chromosomes. Among the A and B groups, chromosome 1 material was consistently detected at high MN frequencies after radiation exposure in all the donors. Additionally, chromosomes 13 and 19 were more frequently observed in micronuclei than the expected frequency based on DNA content. Our whole genome approach utilising the M-FISH technique revealed that MN formation at high radiation doses might be complex involving multiple chromosome fragments. Understanding the fate and biological consequences of these multi-chromosome-containing micronuclei may provide key molecular insights for some aspects of IR

  4. Occupational ionising radiation and risk of basal cell carcinoma in US radiologic technologists (1983-2005).

    PubMed

    Lee, Terrence; Sigurdson, Alice J; Preston, Dale L; Cahoon, Elizabeth K; Freedman, D Michal; Simon, Steven L; Nelson, Kenrad; Matanoski, Genevieve; Kitahara, Cari M; Liu, Jason J; Wang, Timothy; Alexander, Bruce H; Doody, Michele M; Linet, Martha S; Little, Mark P

    2015-12-01

    To determine risk for incident basal cell carcinoma from cumulative low-dose ionising radiation in the US radiologic technologist cohort. We analysed 65,719 Caucasian technologists who were cancer-free at baseline (1983-1989 or 1994-1998) and answered a follow-up questionnaire (2003-2005). Absorbed radiation dose to the skin in mGy for estimated cumulative occupational radiation exposure was reconstructed for each technologist based on badge dose measurements, questionnaire-derived work history and protection practices, and literature information. Radiation-associated risk was assessed using Poisson regression and included adjustment for several demographic, lifestyle, host and sun exposure factors. Cumulative mean absorbed skin dose (to head/neck/arms) was 55.8 mGy (range 0-1735 mGy). For lifetime cumulative dose, we did not observe an excess radiation-related risk (excess relative risk/Gy=-0.01 (95% CI -0.43 to 0.52). However, we observed that basal cell carcinoma risk was increased for radiation dose received before age 30 (excess relative risk/Gy=0.59, 95% CI -0.11 to 1.42) and before 1960 (excess relative risk/Gy=2.92, 95% CI 1.39 to 4.45). Basal cell carcinoma risk was unrelated to low-dose radiation exposure among radiologic technologists. Because of uncertainties in dosimetry and sensitivity to model specifications, both our null results and our findings of excess risk for dose received before age 30 and exposure before 1960 should be interpreted with caution. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  5. Impact ionisation mass spectrometry of polypyrrole-coated pyrrhotite microparticles

    NASA Astrophysics Data System (ADS)

    Hillier, Jon K.; Sternovsky, Zoltan; Armes, Steven P.; Fielding, Lee A.; Postberg, Frank; Bugiel, Sebastian; Drake, Keith; Srama, Ralf; Kearsley, Anton T.; Trieloff, Mario

    2014-07-01

    Cation and anion impact ionization mass spectra of polypyrrole-coated pyrrhotite cosmic dust analogue particles are analysed over a range of cosmically relevant impact speeds. Spectra with mass resolutions of 150-300 were generated by hypervelocity impacts of charged particles, accelerated to up to 37 km s-1 in a Van de Graaff electrostatic accelerator, onto a silver target plate in the Large Area Mass Analyzer (LAMA) spectrometer. Ions clearly indicative of the polypyrrole overlayer are identified at masses of 93, 105, 117, 128 and 141 u. Organic species, predominantly derived from the thin (20 nm) polypyrrole layer on the surface of the particles, dominate the anion spectra even at high (>20 km s-1) impact velocities and contribute significantly to the cation spectra at velocities lower than this. Atomic species from the pyrrhotite core (Fe and S) are visible in all spectra at impact velocities above 6 km s-1 for 56Fe+, 9 km s-1 for 32S+ and 16 km s-1 for 32S- ions. Species from the pyrrhotite core are also frequently visible in cation spectra at impact speeds at which surface ionisation is believed to dominate (<10 km s-1), although the large number of organic peaks complicates the identification of characteristic molecular species. A thin oxidised surface layer on the pyrrhotite particles is indicated by weak spectral features assigned to iron oxides and iron oxy-hydroxides, although the definitive identification of sulfates and hydrated sulfates from the oxidation process was not possible. Silver was confirmed as an excellent choice for the target plate of an impact ionization mass spectrometer, as it provided a unique isotope signature for many target-projectile cluster peaks at masses above 107-109 u. The affinity of Ag towards a dominant organic fragment ion (CN-) derived from fragmentation of the polypyrrole component led to molecular cluster formation. This resulted in an enhanced sensitivity to a particular particle component, which may be of great use

  6. Simulation studies on a prototype ionisation chamber for measurement of personal dose equivalent, Hp(10).

    PubMed

    Cardoso, J; Carvalho, A F; Oliveira, C

    2007-01-01

    A prototype ionisation chamber for direct measurement of the personal dose equivalent, Hp(10), similar to the one developed by the Physikalisch-Technische Bundesantalt (PTB), was designed and constructed by the Metrological Laboratory of Ionizing Radiation (LMRI) of Nuclear and Technological Institute (ITN). Tests already performed have shown that the behaviour of this chamber is very similar to the PTB chamber, mainly the energy dependence for the X-ray radiation qualities of the ISO 4037-1 narrow series N-30, N-40, N-60, N-80, N-100 and N-120 and also for gamma radiation of 137Cs and 60Co. However, the results obtained also show a dependence on the energy and angles of incident radiation and a low magnitude of the electrical response of the ionisation chamber. In order to optimise the performance of the chamber, the LMRI initiated numerical simulation of this ionisation chamber by Monte Carlo method using the MCNPX code.

  7. The ionisation energy of cyclopentadienone: a photoelectron-photoion coincidence study

    NASA Astrophysics Data System (ADS)

    Ormond, Thomas K.; Hemberger, Patrick; Troy, Tyler P.; Ahmed, Musahid; Stanton, John F.; Ellison, G. Barney

    2015-08-01

    Imaging photoelectron photoion coincidence (iPEPICO) spectra of cyclopentadienone (C5H4=O and C5D4=O) have been measured at the Swiss Light Source Synchrotron (Paul Scherrer Institute, Villigen, Switzerland) at the Vacuum Ultraviolet (VUV) Beamline. Complementary to the photoelectron spectra, photoionisation efficiency curves were measured with tunable VUV radiation at the Chemical Dynamics Beamline at the Advanced Light Source Synchrotron (Lawrence Berkeley National Laboratory, Berkeley, CA, USA). For both experiments, molecular beams diluted in argon and helium were generated from the vacuum flash pyrolysis of o-phenylene sulphite in a resistively heated microtubular SiC flow reactor. The Franck-Condon profiles and ionisation energies were calculated at the CCSD(T) level of theory, and are in excellent agreement with the observed iPEPICO spectra. The ionisation energies of both cyclopentadienone-d0, IE(C5H4=O), and cyclopentadienone-d4, IE(C5D4=O), were observed to be the same: 9.41 ± 0.01 eV. The mass-selected threshold photoelectron spectrum (ms-TPES) of cyclopentadienone reveals that the C=C stretch in the ground state of the cation is excited upon ionisation, supporting computational evidence that the ground state of the cation is ? 2A2, and is in agreement with previous studies. However, the previously reported ionisation potential has been improved considerably in this work. In addition, since o-benzoquinone (o-O=C6H4=O and o-O=C6D4=O) is also produced in this process, its ms-TPES has been recorded. From the iPEPICO and photoionisation efficiency spectra, we infer an adiabatic ionisation energy of IE(o-O=C6H4=O) = 9.3 ± 0.1 eV, but the rather structureless spectrum indicates a strong change in geometry upon ionisation making this value less reliable.

  8. Dynamics of ionisation and entanglement in the 'atom + quantum electromagnetic field' system

    SciTech Connect

    Sharapova, P R; Tikhonova, O V

    2012-03-31

    The dynamics of a model Rydberg atom in a strong nonclassical electromagnetic field is investigated. The field-induced transitions to the continuum involving different numbers of photons (with intermediate states in the discrete spectrum) are taken into account and the specific features of ionisation in 'squeezed' field states are considered in comparison with the case of classical light. A significant decrease in the ionisation rate is found, which is caused by the interference stabilisation of the atomic system. The entanglement of the atomic and field subsystems, the temporal dynamics of the correlations found, and the possibility of measuring them are analysed.

  9. Molybdic acid ionisation under hydrothermal conditions to 300 °C

    NASA Astrophysics Data System (ADS)

    Minubayeva, Z.; Seward, T. M.

    2010-08-01

    This UV spectrophotometric study was aimed at providing precise, experimentally derived thermodynamic data for the ionisation of molybdic acid (H 2MoO 4) from 30 to 300 °C and at equilibrium saturated vapour pressures. The determination of the equilibrium constants and associated thermodynamic parameters were facilitated by spectrophotometric measurements using a specially designed high temperature optical Ti-Pd flow-through cell with silica glass windows. The following van't Hoff isochore equations describe the temperature dependence of the first and second ionisation constants of molybdic acid up to 300 °C:

  10. A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry.

    PubMed

    Murawski, Ł; Zielczyński, M; Golnik, N; Gryziński, M A

    2014-10-01

    A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge.

  11. Caractérisation du seuil d'ablation des parois dans les sources de rayonnement EUV par décharge capillaire

    NASA Astrophysics Data System (ADS)

    Sarroukh, O.; Robert, E.; Kaiser, J.; Viladrosa, R.; Pouvesle, J. M.; Fleurier, C.; Cachoncinlle, C.

    2005-06-01

    Les sources de rayonnement Extrême Ultraviolet (EUV) par décharge capillaire connaissent un intérêt de plus en plus considérable pour de nombreuses applications scientifiques et technologiques. Au GREMI, nous étudions le fonctionnement des sources de rayonnement EUV émettant à 13.5 nm pouvant répondre à certaines applications liées à la nouvelle génération de la lithographie. Ces sources pulsées, nommées CAPELLA, ATλ AS et PROXIMA, sont basées sur une décharge capillaire en flux de gaz. Ce type de décharge produit un plasma chaud, dense et fortement ionisé émettant dans la gamme spectrale de l'EUV. En effet, les températures électroniques peuvent atteindre des dizaines d'électronvolts et les densités électroniques sont de l'ordre de 1017 cm-3. Les échanges thermiques entre le plasma ainsi créé et les parois du capillaire peuvent être suffisamment important pour que les parois du capillaire soient ablatées. Cette ablation peut être plus ou moins importante selon la densité d'énergie injectée dans le capillaire. Des mesures spectroscopiques du plasma émetteur dans les gammes spectrales de l'UV et l'EUV ont montré la présence d'un seuil d'ablation situé autour de à 350 J.cm-3. Nous utilisons un modèle thermique présenté [1] pour modéliser l'évolution temporelle de la température des parois du capillaire. Le seuil peut être ainsi estimé. Les résultats expérimentaux obtenus à partir de nos mesures spectroscopiques sont comparés ensuite aux résultats numériques.

  12. Annealing of GaSb Single Crystals in Ionised Hydrogen Atmosphere

    DTIC Science & Technology

    2001-01-01

    and Applications 46 of Single Crystals, Antoni Rogaski, Krzysztof Adamiec, Pawel Madejczyk, Editors, Proceedings of SPIE Vol. 4412 (2001) © 2001...1-50 hours. Hydrogen ionised by means of a deuterium lamp flew through this annealing reactor. After cooling the quartz ampoule, the carrier

  13. The Effects of Ionising Radiation on MEMS Silicon Strain Gauges: Preliminary Background and Methodology

    DTIC Science & Technology

    2006-09-01

    tuneable radar, structural health monitoring (corrosion and strain sensing) and power production . 2. Ionising Radiation Susceptibility of...materials this displacement damage affects the electronic energy states, which can give rise to several processes, including increased thermal ...are smaller and lighter than the current generation of detectors. The lower costs associated with mass- production of MEMS could also allow greater

  14. Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

    PubMed

    Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

    2007-01-01

    Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material.

  15. For discussion: obtaining consent for ionising radiation: has the time come?

    PubMed

    Mendelson, Richard M

    2010-10-01

    The aim of this paper is to promote debate on the issues surrounding the provision of information to, and the obtaining of valid consent from patients exposed to ionising radiation (IR) from diagnostic and interventional imaging procedures. This is especially pertinent in view of recent interest in the risks of IR expressed in the medical and lay press.

  16. Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

    ERIC Educational Resources Information Center

    Wheeldon, Ruth

    2012-01-01

    Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in "J Chem Educ" 86(5):623-629, 2009). This research extends this work by…

  17. Exploring Learners' Conceptual Resources: Singapore a Level Students' Explanations in the Topic of Ionisation Energy

    ERIC Educational Resources Information Center

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2007-01-01

    This paper describes findings from a study to explore Singapore A-level (Grades 11 and 12, 16-19 yr old) students' understanding of ionisation energy, an abstract and complex topic that is featured in school chemistry courses. Previous research had reported that students in the United Kingdom commonly use alternative notions based on the perceived…

  18. The impact of high and low dose ionising radiation on the central nervous system.

    PubMed

    Betlazar, Calina; Middleton, Ryan J; Banati, Richard B; Liu, Guo-Jun

    2016-10-01

    Responses of the central nervous system (CNS) to stressors and injuries, such as ionising radiation, are modulated by the concomitant responses of the brains innate immune effector cells, microglia. Exposure to high doses of ionising radiation in brain tissue leads to the expression and release of biochemical mediators of 'neuroinflammation', such as pro-inflammatory cytokines and reactive oxygen species (ROS), leading to tissue destruction. Contrastingly, low dose ionising radiation may reduce vulnerability to subsequent exposure of ionising radiation, largely through the stimulation of adaptive responses, such as antioxidant defences. These disparate responses may be reflective of non-linear differential microglial activation at low and high doses, manifesting as an anti-inflammatory or pro-inflammatory functional state. Biomarkers of pathology in the brain, such as the mitochondrial Translocator Protein 18kDa (TSPO), have facilitated in vivo characterisation of microglial activation and 'neuroinflammation' in many pathological states of the CNS, though the exact function of TSPO in these responses remains elusive. Based on the known responsiveness of TSPO expression to a wide range of noxious stimuli, we discuss TSPO as a potential biomarker of radiation-induced effects.

  19. Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

    ERIC Educational Resources Information Center

    Wheeldon, Ruth

    2012-01-01

    Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in "J Chem Educ" 86(5):623-629, 2009). This research extends this work by…

  20. Atomic data needs for X-ray spectroscopy of photo-ionised plasmas

    NASA Astrophysics Data System (ADS)

    Kaastra, Jelle S.

    2005-05-01

    High-resolution X-ray spectroscopy of Active Galactic Nuclei has become possible thanks to the launch of XMM-Newton and Chandra with their grating spectrometers, and will be explored further after the expected launch of ASTRO-E2 with its XRS detector. In several AGN the X-ray spectra show the signatures of on outflowing, photo-ionised wind. Also several X-ray binaries show a similar imprint of a photo-ionised gas. The clearest signatures are formed by the broad range of absorption lines, mostly from the ground states of a wide range of ionisation states of the abundant elements. In addition to absorption lines due to the valence electrons, the spectra show many inner-shell absorption lines. Examples are the K-shell transitions of the most abundant metal, oxygen, in the 19-23 Å band, and 2p-3d transitions of lowly ionised iron in the 15-17 Å region. These transitions have an extremely important diagnostic value, as other transitions of the same ions frequently occur in the unobservable extreme ultraviolet. Several of these inner-shell transitions, however, lack accurate experimental or theoretical wavelengths, which makes the spectral analysis complicated and ambiguous. This is even more the case for transitions from metastable levels, which can be used as density diagnostics. Finally, attention is payed to the role of atomic data in the photo-ionisation equilibrium calculations. Uncertainties in for example dielectronic recombination rates cause large uncertainties in the predicted absorption line strengths.

  1. Student and intern awareness of ionising radiation exposure from common diagnostic imaging procedures.

    PubMed

    Zhou, G Z; Wong, D D; Nguyen, L K; Mendelson, R M

    2010-02-01

    This study aims to evaluate medical student and intern awareness of ionising radiation exposure from common diagnostic imaging procedures and to suggest how education could be improved. Fourth to sixth year medical students enrolled at a Western Australian university and interns from three teaching hospitals in Perth were recruited. Participants were asked to complete a questionnaire consisting of 26 questions on their background, knowledge of ionising radiation doses and learning preferences for future teaching on this subject. A total of 331 completed questionnaires were received (95.9%). Of the 17 questions assessing knowledge of ionising radiation, a mean score of 6.0 was obtained by respondents (95% CI 5.8-6.2). Up to 54.8% of respondents underestimated the radiation dose from commonly requested radiological procedures. Respondents (11.3 and 25.5%) incorrectly believed that ultrasound and MRI emit ionising radiation, respectively. Of the four subgroups of respondents, the intern doctor subgroup performed significantly better (mean score 6.9, P < 0.0001, 95% CI 6.5-7.3) than each of the three medical student subgroups. When asked for the preferred method of teaching for future radiation awareness, a combination of lectures, tutorials and workshops was preferred. This study has clearly shown that awareness of ionising radiation from diagnostic imaging is lacking among senior medical students and interns. The results highlight the need for improved education to minimise unnecessary exposure of patients and the community to radiation. Further studies are required to determine the most effective form of education.

  2. Destruction of Raman biosignatures by ionising radiation and the implications for life detection on Mars.

    PubMed

    Dartnell, Lewis R; Page, Kristian; Jorge-Villar, Susana E; Wright, Gary; Munshi, Tasnim; Scowen, Ian J; Ward, John M; Edwards, Howell G M

    2012-04-01

    Raman spectroscopy has proven to be a very effective approach for the detection of microorganisms colonising hostile environments on Earth. The ExoMars rover, due for launch in 2018, will carry a Raman laser spectrometer to analyse samples of the martian subsurface collected by the probe's 2-m drill in a search for similar biosignatures. The martian surface is unprotected from the flux of cosmic rays, an ionising radiation field that will degrade organic molecules and so diminish and distort the detectable Raman signature of potential martian microbial life. This study employs Raman spectroscopy to analyse samples of two model organisms, the cyanobacterium Synechocystis sp. PCC 6803 and the extremely radiation resistant polyextremophile Deinococcus radiodurans, that have been exposed to increasing doses of ionising radiation. The three most prominent peaks in the Raman spectra are from cellular carotenoids: deinoxanthin in D. radiodurans and β-carotene in Synechocystis. The degradative effect of ionising radiation is clearly seen, with significant diminishment of carotenoid spectral peak heights after 15 kGy and complete erasure of Raman biosignatures by 150 kGy of ionising radiation. The Raman signal of carotenoid in D. radiodurans diminishes more rapidly than that of Synechocystis, believed to be due to deinoxanthin acting as a superior scavenger of radiolytically produced reactive oxygen species, and so being destroyed more quickly than the less efficient antioxidant β-carotene. This study highlights the necessity for further experimental work on the manner and rate of degradation of Raman biosignatures by ionising radiation, as this is of prime importance for the successful detection of microbial life in the martian near subsurface.

  3. Multicolour FISH analysis of ionising radiation induced micronucleus formation in human lymphocytes.

    PubMed

    Balajee, Adayabalam S; Bertucci, Antonella; Taveras, Maria; Brenner, David J

    2014-11-01

    Micronucleation of chromosomal DNA is an effective indicator of DNA damage and micronucleus (MN) analysis is a valuable tool for radiation biodosimetry studies. To gain a comprehensive knowledge of micronucleation process after ionising radiation (IR) exposure, whole genome-wide chromosome analysis is desirable. With this objective, multicolour fluorescence in situ hybridization (M-FISH) technique was utilised in the present study to characterise the chromosome content of spontaneous and IR-induced micronuclei in three human donors. M-FISH analysis revealed a radiation dose-dependant increase in the number of micronuclei with multi-chromosome material above 2 Gy and as many as 3-6 multicolour signals were detected in micronuclei after high γ-rays radiation doses (5-10 Gy). Involvement of each human chromosome material was more frequently detected in multicoloured micronuclei than in single-coloured micronuclei at high radiation doses (>2 Gy). Observation of dose-dependant increase in the MN frequency with multi-chromosome material may be due to misrepair of DNA double-strand breaks involving multiple chromosomes leading to asymmetric dicentric or ring chromosomes and acentric fragments. Chromosomes belonging to groups A (1, 2 and 3) and B (4 and 5) were frequently detected in 35-45% of the total micronuclei either as single entities or in combination with other chromosomes. Among the A and B groups, chromosome 1 material was consistently detected at high MN frequencies after radiation exposure in all the donors. Additionally, chromosomes 13 and 19 were more frequently observed in micronuclei than the expected frequency based on DNA content. Our whole genome approach utilising the M-FISH technique revealed that MN formation at high radiation doses might be complex involving multiple chromosome fragments. Understanding the fate and biological consequences of these multi-chromosome-containing micronuclei may provide key molecular insights for some aspects of IR

  4. Electron impact ionisation of encapsulated 99mTc@C 60 and 99mTc@C 70

    NASA Astrophysics Data System (ADS)

    Đustebek, J. B.; Đorđević, V. R.; Cvetićanin, J. M.; Veličković, S. R.; Veljković, M. V.; Nešković, O. M.; Rakočević, Z. L.; Bibić, N. M.

    2010-03-01

    The present study shows simultaneous surface ionisation and electron impact ionisation during the formation and investigation of endohedral fullerenes 99mTc@C 60 and 99mTc@C 70. The endohedral fullerenes were generated using a mass spectrometer with a triple rhenium filament as an ion source. The ionisation energies (IE) determined were: 8.52 ± 0.25 eV for 99mTc@C 60 and 9.57 ± 0.25 eV for 99mTc@ C 70.

  5. How do air ions reflect variations in ionising radiation in the lower atmosphere in a boreal forest?

    NASA Astrophysics Data System (ADS)

    Chen, Xuemeng; Kerminen, Veli-Matti; Paatero, Jussi; Paasonen, Pauli; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Kulmala, Markku

    2016-11-01

    Most of the ion production in the atmosphere is attributed to ionising radiation. In the lower atmosphere, ionising radiation consists mainly of the decay emissions of radon and its progeny, gamma radiation of the terrestrial origin as well as photons and elementary particles of cosmic radiation. These types of radiation produce ion pairs via the ionisation of nitrogen and oxygen as well as trace species in the atmosphere, the rate of which is defined as the ionising capacity. Larger air ions are produced out of the initial charge carriers by processes such as clustering or attachment to pre-existing aerosol particles. This study aimed (1) to identify the key factors responsible for the variability in ionising radiation and in the observed air ion concentrations, (2) to reveal the linkage between them and (3) to provide an in-depth analysis into the effects of ionising radiation on air ion formation, based on measurement data collected during 2003-2006 from a boreal forest site in southern Finland. In general, gamma radiation dominated the ion production in the lower atmosphere. Variations in the ionising capacity came from mixing layer dynamics, soil type and moisture content, meteorological conditions, long-distance transportation, snow cover attenuation and precipitation. Slightly similar diurnal patterns to variations in the ionising capacity were observed in air ion concentrations of the cluster size (0.8-1.7 nm in mobility diameters). However, features observed in the 0.8-1 nm ion concentration were in good connection to variations of the ionising capacity. Further, by carefully constraining perturbing variables, a strong dependency of the cluster ion concentration on the ionising capacity was identified, proving the functionality of ionising radiation in air ion production in the lower atmosphere. This relationship, however, was only clearly observed on new particle formation (NPF) days, possibly indicating that charges after being born underwent different

  6. Exploring the Powerful Ionised Wind in the Seyfert Galaxy PG1211+143

    NASA Astrophysics Data System (ADS)

    Pounds, Ken

    2013-10-01

    Highly-ionised high-speed winds in AGN (UFOs) were first detected with XMM-Newton a decade ago, and are now established as a key factor in the study of SMBH accretion, and in the growth and metal enrichment of their host galaxies. However, information on the ionisation and dynamical structure, and the ultimate fate of UFOs remains very limited. We request a 600ks extended XMM-Newton study of the prototype UFO PG1211+143 in AO-13, to obtain high quality EPIC and RGS spectra, to map the flow structure and variability, while seeking evidence for the anticipated interaction with the ISM and possible conversion of the energetic wind to a momentum-driven flow.

  7. The nature of the ionised nebula surrounding the red supergiant W26

    NASA Astrophysics Data System (ADS)

    Wesson, Roger

    2015-08-01

    The red supergiant W26 in the massive star cluster Westerlund 1 is surrounded by a compact ionised nebula. This is unique among RSGs, and the excitation mechanism of the nebula is not yet known - it may be ionised by an unseen compact companion, or by a nearby blue supergiant. We present new observations of the nebula: high resolution spatially resolved spectra taken with FLAMES at the VLT show that the nebula is a ring, with velocities consistent with that expected for red supergiant ejecta, and ruling out the possibility of a Luminous Blue Variable-type eruption preceding the RSG phase as the origin of the nebula. A triangular patch of nebulosity outside the ring appears to be associated with W26, and may be material stripped from the expanding ring by the cumulative cluster wind and radiation field.

  8. Angular distribution of electrons in multiphoton ionisation of polarised Lithium atoms

    NASA Astrophysics Data System (ADS)

    Klimova, Yu. A.; Marmo, S. I.; Meremianin, A. V.

    2013-09-01

    The asymmetry of the angular distributions of photoelectrons in the photoionisation of polarised alkali atoms is investigated. The general formulas for the amplitude of the multiphoton ionisation of np-states are given. In these formulas the dynamical and kinematical factors are explicitly separated. Our calculations within Fues model potential approach demonstrate that, under the experimental conditions essentially similar to those employed in [M. Schuricke, Ganjun Zhu, J. Steinmann, K. Simeonidis, I. Ivanov, A. Kheifets, A.N. Grum-Grzhimailo, K. Bartschat, A. Dorn, J. Ullrich, Phys. Rev. A 83 (2011) 023413(11)], the relative magnitude of the linear magnetic dichroism in three-photon ionisation of Li can be as large as 30%.

  9. Electrospray ionisation-cleavable tandem nucleic acid mass tag–peptide nucleic acid conjugates: synthesis and applications to quantitative genomic analysis using electrospray ionisation-MS/MS

    PubMed Central

    Thompson, Andrew; Prescott, Mark; Chelebi, Noorhan; Smith, John; Brown, Tom; Schmidt, Günter

    2007-01-01

    The synthesis and characterization of isotopomer tandem nucleic acid mass tag–peptide nucleic acid (TNT–PNA) conjugates is described along with their use as electrospray ionisation-cleavable (ESI-Cleavable) hybridization probes for the detection and quantification of target DNA sequences by electrospray ionisation tandem mass spectrometry (ESI-MS/MS). ESI-cleavable peptide TNT isotopomers were introduced into PNA oligonucleotide sequences in a total synthesis approach. These conjugates were evaluated as hybridization probes for the detection and quantification of immobilized synthetic target DNAs using ESI-MS/MS. In these experiments, the PNA portion of the conjugate acts as a hybridization probe, whereas the peptide TNT is released in a collision-based process during the ionization of the probe conjugate in the electrospray ion source. The cleaved TNT acts as a uniquely resolvable marker to identify and quantify a unique target DNA sequence. The method should be applicable to a wide variety of assays requiring highly multiplexed, quantitative DNA/RNA analysis, including gene expression monitoring, genetic profiling and the detection of pathogens. PMID:17259215

  10. Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Gordienko, A. V.; Mavritskii, O. B.; Egorov, A. N.; Pechenkin, A. A.; Savchenkov, D. V.

    2014-12-01

    The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed.

  11. Effect of radiation-induced charge accumulation on build-up cap on the signal current from an ionisation chamber.

    PubMed

    Takata, N; Morishita, Y

    2011-04-01

    The signal current from a thimble ionisation chamber with a build-up cap made of an insulator decreases by about 0.41 % after being irradiated for 17 h at an air kerma rate of 41 Gy h(-1) by a collimated (60)Co gamma-ray beam in air. In contrast, the signal current remains constant when the thimble ionisation chamber is irradiated in a water phantom. During irradiation, positive charge is considered to accumulate near the outer surface of the build-up cap where electron equilibrium is not achieved. Secondary electrons travelling in the build-up cap and the chamber wall toward the ionisation volume are decelerated by the electric field generated by the positive charge. Consequently, the signal current decreases with increasing charge accumulation because some secondary electrons are prevented from entering the ionisation volume. In the water phantom, electron equilibrium is established in and around the ionisation chamber and charge does not accumulate. To confirm this hypothesis, the signal current was measured for an ionisation chamber in air with a build-up cap wrapped with Al foil and covered with PMMA tubes. Electron equilibrium was established over the build-up cap because the tubes were thicker than the secondary electron range. The signal current decreased with increasing positive voltage applied to the Al foil. It was estimated from the results that positive charges equivalent to a voltage of over 6 kV applied to the Al foil accumulated during irradiation. The signal current was also measured for an ionisation chamber with a metal build-up cap and for an ionisation chamber with a wall and build-up cap made of conductive plastic.

  12. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  13. Migration to new ampoule types for the NPL secondary standard ionisation chambers.

    PubMed

    Baker, M; Fenwick, A; Ferreira, K; Keightley, J; Johansson, L; Collins, S

    2014-05-01

    As the pre-calibrated sample containers used for activity assay in the two NPL secondary standards ionisation chambers are being phased out, suitable replacements have been identified. Characterisation checks have been carried out on the new ISO ampoules and a long-term recalibration schedule has been devised. Around 40 calibration factors have been determined so far and comparison of ion chamber responses for the two ampoule types showed variations of up to 7% for low energy photon emitting radionuclides.

  14. Ab-initio surface hopping and multiphoton ionisation study of the photodissociation dynamics of CS2

    NASA Astrophysics Data System (ADS)

    Bellshaw, Darren; Horke, Daniel A.; Smith, Adam D.; Watts, Hannah M.; Jager, Edward; Springate, Emma; Alexander, Oliver; Cacho, Cephise; Chapman, Richard T.; Kirrander, Adam; Minns, Russell S.

    2017-09-01

    New ab initio surface hopping simulations of the excited state dynamics of CS2 including spin-orbit coupling are compared to new experimental measurements using a multiphoton ionisation probe in a photoelectron spectroscopy experiment. The calculations highlight the importance of the triplet states even in the very early time dynamics of the dissociation process and allow us to unravel the signatures in the experimental spectrum, linking the observed changes to both electronic and nuclear degrees of freedom within the molecule.

  15. Changes in plasma characteristics caused by easily ionisable elements in hollow cathode discharge emission spectrography.

    PubMed

    Szilvássy-Vámos, Z; Gyódrfi-Buzási, A; Pásztor, Z

    1991-11-01

    The effect of several concomitant easily ionisable elements (EIE's), Li, Na, K, Rb and Cs on the line intensity of Sr II (first ionised state) and Al I and He I (atomic states) has been studied by atomic emission spectrometry (AES) hollow cathode (HCD) analysis. The spectral line intensities emitted by Sr II, Al I and He I have been measured while varying the volume of the EIE's concentrations, ranging from 0.1 mg ml to 10 mg ml. In the presence of EIE's at higher concentrations than 0.5% a considerable decrease of the line intensities of Sr II at 430.54 nm and 407.71 nm was observed, together with a gradual decrease in the line intensities of both Al I 494.40 nm and 396.15 nm, and He I 412.1 nm. It is demonstrated in the present experiments with a water-cooled HCD source that interference effects caused by EIE's are observed when the ratio of the number of gas atoms (n(g)) and atoms with low ionisation energy (n(a))n(g)/n(a)is lower than 10(12).

  16. Examining Pre-Service Teachers' Use of Atomic Models in Explaining Subsequent Ionisation Energy Values

    NASA Astrophysics Data System (ADS)

    Wheeldon, Ruth

    2012-06-01

    Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in J Chem Educ 86(5):623-629, 2009). This research extends this work by considering which atomic models are used in pre-service teachers' explanations and how that relates to the causality ideas expressed. Thirty-one pre-service teachers were interviewed. Each was asked to describe and explain four different atomic representations (Rutherford, Electron cloud micrograph, Bohr and Schrödinger types) in as much detail as they could. They also provided an explanation for the subsequent ionisation energy values for an oxygen atom and identified which representations were helpful in explaining the values. Significantly, when pre-service teachers only used Bohr type representations, they did not use repelling electron ideas in their explanations. However, arguments that were based on electron-electron repulsion used features from Schrödinger type atoms. These findings suggest that many pre-service teachers need to develop their atomic modelling skills so that they select and use models more expertly and that subsequent ionisation explanations offer a context in which to explore different atomic models' limitations and their deployment as explanatory resources.

  17. Is copper-silver ionisation safe and effective in controlling legionella?

    PubMed

    Cachafeiro, S Perez; Naveira, I Mato; García, I González

    2007-11-01

    Copper-silver ionisation is gaining popularity worldwide as a water disinfection method. We review the literature that supports the effectiveness and safety of the copper-silver ionisation pertaining to legionella control in water distribution systems. A search between January 1997 and January 2007 was conducted in relevant health databases: Medline, Embase, NHS CRD, Cochrane Library Plus, Web of Knowledge, IME (Spanish Medical Index) and IBECS (Health Sciences Bibliographic Index). Ten published studies were selected according to inclusion and exclusion criteria previously established; most of these were experimental. Legionella levels decrease with the application of any of the procedures used in these studies and the procedures can be combined to obtain better outcomes. No studies containing an economic evaluation were found. We conclude that copper-silver ionisation is an effective method to control legionella, bearing in mind that eradication cannot be achieved by any method in isolation. Maintaining high temperatures in the water system can maximise effectiveness of the method. Copper-silver appears to be safe, as long as ion levels are monitored and kept within international recommended levels. More studies with concurrent control group, long follow-up and economic evaluation are required to properly assess this procedure.

  18. A Carbon Nano Tube electron impact ionisation source for low-power, compact spacecraft mass spectrometers

    NASA Astrophysics Data System (ADS)

    Sheridan, S.; Bardwell, M. W.; Morse, A. D.; Morgan, G. H.

    2012-04-01

    A novel ionisation source which uses commercially available Carbon Nano Tube devices is demonstrated as a replacement for a filament based ionisation source in an ion trap mass spectrometer. The carbon nanotube ion source electron emission was characterised and exhibited typical emission of 30 ± 1.7 μA with an applied voltage differential of 300 V between the carbon nanotube tips and the extraction grid. The ion source was tested for longevity and operated under a condition of continuous emission for a period of 44 h; there was an observed reduction in emission current of 26.5% during operation. Spectra were generated by installing the ion source into a Finnigan Mat ITD700 ion trap mass spectrometer; the spectra recorded showed all of the characteristic m/z peaks from m/z 69 to m/z 219. Perfluorotributylamine spectra were collected and averaged contiguously for a period of 48 h with no significant signal loss or peak mass allocation shift. The low power requirements and low mass of this novel ionisation source are considered be of great value to future space missions where mass spectrometric technology will be employed.

  19. Field calibration studies for ionisation chambers in mixed high-energy radiation fields.

    PubMed

    Theis, C; Forkel-Wirth, D; Fuerstner, M; Mayer, S; Otto, Th; Roesler, S; Vincke, H

    2007-01-01

    The monitoring of ambient doses at work places around high-energy accelerators is a challenging task due the complexity of the mixed stray radiation fields encountered. At CERN, mainly Centronics IG5 high-pressure ionisation chambers are used to monitor radiation exposure in mixed fields. The monitors are calibrated in the operational quantity ambient dose equivalent H*(10) using standard, source-generated photon- and neutron fields. However, the relationship between ionisation chamber reading and ambient dose equivalent in a mixed high-energy radiation field can only be assessed if the spectral response to every component and the field composition is known. Therefore, comprehensive studies were performed at the CERN-EU high-energy reference field facility where the spectral fluence for each particle type has been assessed with Monte Carlo simulations. Moreover, studies have been performed in an accessible controlled radiation area in the vicinity of a beam loss point of CERN's proton synchrotron. The comparison of measurements and calculations has shown reasonable agreement for most exposure conditions. The results indicate that conventionally calibrated ionisation chambers can give satisfactory response in terms of ambient dose equivalent in stray radiation fields at high-energy accelerators in many cases. These studies are one step towards establishing a method of 'field calibration' of radiation protection instruments in which Monte Carlo simulations will be used to establish a correct correlation between the response of specific detectors to a given high-energy radiation field.

  20. Radiation in the workplace-a review of studies of the risks of occupational exposure to ionising radiation.

    PubMed

    Wakeford, Richard

    2009-06-01

    Many individuals are, or have been, exposed to ionising radiation in the course of their work and the epidemiological study of occupationally irradiated groups offers an important opportunity to complement the estimates of risks to health resulting from exposure to radiation that are obtained from other populations, such as the Japanese survivors of the atomic bombings of Hiroshima and Nagasaki in 1945. Moreover, workplace exposure to radiation usually involves irradiation conditions that are of direct relevance to the principal concern of radiological protection: protracted exposure to low level radiation. Further, some workers have been exposed to radioactive material that has been inadvertently taken into the body, and the study of these groups leads to risk estimates derived directly from the experience of those irradiated by these 'internal emitters', intakes of alpha-particle-emitters being of particular interest. Workforces that have been the subject of epidemiological study include medical staff, aircrews, radium dial luminisers, underground hard-rock miners, Chernobyl clean-up workers, nuclear weapons test participants and nuclear industry workers. The first solid epidemiological evidence of the stochastic effects of irradiation came from a study of occupational exposure to medical x-rays that was reported in 1944, which demonstrated a large excess risk of leukaemia among US radiologists; but the general lack of dose records for early medical staff who tended to experience the highest exposures hampers the derivation of risks per unit dose received by medical workers. The instrument dial luminisers who inadvertently ingested large amounts of radium-based paint and underground hard-rock miners who inhaled large quantities of radon and its decay products suffered markedly raised excess risks of, respectively, bone and lung cancers; the miner studies have provided standard risk estimates for radon-induced lung cancer. The large numbers of nuclear industry

  1. KINETIC SIMULATIONS OF THERMOLUMINESCENCE DOSE RESPONSE: LONG OVERDUE CONFRONTATION WITH THE EFFECTS OF IONISATION DENSITY.

    PubMed

    Horowitz, Y S; Eliyahu, I; Oster, L

    2016-12-01

    The reader will time-travel through almost seven decades of kinetic models and mathematical simulations of thermoluminescence (TL) characteristics based on the band-gap theory of the solid state. From post-World-War II, ideas concerning electron trapping mechanisms to the highly idealised one trap-one recombination (OTOR) model first elaborated in 1956 but still in 'high gear' today. The review caresses but purposely avoids in-depth discussion of the endless stream of papers discussing the intricacies of glow peak shapes arising from first-order, second-order, mixed-order and general-order kinetics predominantly based on non-interacting systems, and then on to the more physically realistic scenarios that have attempted to analyse complex systems involving ever greater numbers of interacting trapping centres, luminescent centres and non-luminescent centres. The review emphasises the difficulty the band-gap models have in the simulation of dose response linear/supralinear behaviour and especially the dependence of the supralinearity on ionisation density. The significance of the non-observation of filling-rate supralinearity in the absorption stage is emphasised since it removes from consideration the possibility of TL supralinearity arising from irradiation stage supralinearity. The importance of the simultaneous action of both localised and delocalised transitions has gradually penetrated the mindset of the community of kinetic researchers, but most simulations have concentrated on the shape of glow peaks and the extraction of the glow peak parameters, E (the thermal activation energy) and s (the attempt-to-escape frequency). The simulation of linear/supralinear dose response and its dependence on ionisation density have been largely avoided until recently due to the fundamental schism between the effects of ionisation density and some basic assumptions of the band-gap model. The review finishes with an in-depth presentation and discussion of the most recent

  2. Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities.

    PubMed

    Coe, Jeremy P; Taylor, Daniel J; Paterson, Martin J

    2013-05-15

    The method of Monte Carlo configuration interaction (MCCI) (Greer, J. Chem. Phys. 1995a, 103, 1821; Tong, Nolan, Cheng, and Greer, Comp. Phys. Comm. 2000, 142, 132) is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of N2 and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these nonvariational quantities may be found to relatively good accuracy when compared with full configuration interaction results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration interaction quantum Monte Carlo (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112) and "exact" nonrelativistic results (Booth and Alavi, J. Chem. Phys. 2010, 132, 174104; Cleland, Booth, and Alavi, J. Chem. Phys. 2011, 134, 024112). We show that MCCI could be a useful alternative for the calculation of atomic ionisation energies however electron affinities appear much more challenging for MCCI. Due to the small magnitude of the electron affinities their percentage errors can be high, but with regards to absolute errors MCCI performs similarly for ionisation energies and electron affinities.

  3. IFU Spectroscopy of Southern Planetary Nebulae V: Low-Ionisation Structures

    NASA Astrophysics Data System (ADS)

    Ali, A.; Dopita, M. A.

    2017-08-01

    In this fifth paper of the series, we examine the spectroscopy and morphology of four southern Galactic planetary nebulae Hen 2-141, NGC 5307, IC 2553, and PB 6 using new integral field spectroscopy data. The morphologies and ionisation structures of the sample are given as a set of emission-line maps. In addition, the physical conditions, chemical compositions, and kinematical characteristics of these objects are derived. The results show that PB 6 and Hen 2-141 are of very high excitation classes and IC 2553 and NGC 5307 are mid to high excitation objects. The elemental abundances reveal that PB 6 is of Type I, Hen 2-141 and IC 2553 are of Type IIa, and NGC 5307 is of Type IIb/III. The observations unveil the presence of well-defined low-ionisation structures or `knots' in all objects. The diagnostic diagrams reveal that the excitation mechanism of these knots is probably by photoionisation of dense material by the nebular central stars. The physical analysis of six of these knots show no significant differences with their surrounding nebular gas, except their lower electron densities. In spite of the enhancement of the low-ionisation emission lines of these knots, their chemical abundances are nearly comparable to their surrounding nebulae, with the exception of perhaps slightly higher nitrogen abundances in the NGC 5307 knots. The integrated spectrum of IC 2553 reveals that nearly all key lines that have led researchers to characterise its central star as a weak-emission line star type are in fact of nebular origin.

  4. Impact ionisation spectra from hypervelocity impacts using aliphatic poly(methyl methacrylate) microparticle projectiles.

    PubMed

    Burchell, Mark J; Armes, Steven P

    2011-02-28

    We report impact ionisation spectra from spherical poly(methyl methacrylate) (PMMA) microparticles of 724 nm diameter impacting a rhodium target. These projectiles were coated with an ultrathin (~11 nm) overlayer of polypyrrole, an electrically conducting organic polymer; this enabled the accumulation of sufficient surface charge to allow electrostatic acceleration up to speeds of 4 to 8 km s(-1) using a high-voltage Van de Graaff instrument. A grid above the target (held at 3.33 kV cm(-1) with respect to the target) accelerated the cations that were generated during the hypervelocity impacts, and these ions then drifted to a charge detector. By measuring the collected charge vs. time and assuming only single ionisation events, time-of-flight mass spectra were obtained. Strong signals were observed for cationic species with ions of m/z 41, 65 and 115. There were also minor contributions from cations with masses ranging from m/z 29 to 142. The three major signals are assigned to fragment ions (C(3)H(5)(+), C(4)H(5)O(+)/C(5)H(9)(+) and C(6)H(11)O(2)(+)) which are known to be associated with the decomposition of PMMA. These impact ionisation spectra differ significantly from those reported earlier using polystyrene (PS) microparticles. The aliphatic PMMA microparticles generate small (m/z <100) fragment ions more readily at lower speeds than the predominantly aromatic PS microparticles, where speeds of at least 10 km s(-1) are typically required for substantial yields of low-mass fragment ions. This correlates well with the well-known greater chemical and thermal fragility of PMMA compared to PS. The PMMA microparticles should prove useful synthetic mimics for aliphatic carbonaceous micrometeorites. Copyright © 2011 John Wiley & Sons, Ltd.

  5. Expression of the progenitor marker NG2/CSPG4 predicts poor survival and resistance to ionising radiation in glioblastoma.

    PubMed

    Svendsen, Agnete; Verhoeff, Joost J C; Immervoll, Heike; Brøgger, Jan C; Kmiecik, Justyna; Poli, Aurelie; Netland, Inger A; Prestegarden, Lars; Planagumà, Jesús; Torsvik, Anja; Kjersem, Anneli Bohne; Sakariassen, Per Ø; Heggdal, Jan I; Van Furth, Wouter R; Bjerkvig, Rolf; Lund-Johansen, Morten; Enger, Per Ø; Felsberg, Joerg; Brons, Nicolaas H C; Tronstad, Karl J; Waha, Andreas; Chekenya, Martha

    2011-10-01

    Glioblastoma (GBM) is a highly aggressive brain tumour, where patients respond poorly to radiotherapy and exhibit dismal survival outcomes. The mechanisms of radioresistance are not completely understood. However, cancer cells with an immature stem-like phenotype are hypothesised to play a role in radioresistance. Since the progenitor marker neuron-glial-2 (NG2) has been shown to regulate several aspects of GBM progression in experimental systems, we hypothesised that its expression would influence the survival of GBM patients. Quantification of NG2 expression in 74 GBM biopsies from newly diagnosed and untreated patients revealed that 50% express high NG2 levels on tumour cells and associated vessels, being associated with significantly shorter survival. This effect was independent of age at diagnosis, treatment received and hypermethylation of the O(6)-methylguanine methyltransferase (MGMT) DNA repair gene promoter. NG2 was frequently co-expressed with nestin and vimentin but rarely with CD133 and the NG2 positive tumour cells harboured genetic aberrations typical for GBM. 2D proteomics of 11 randomly selected biopsies revealed upregulation of an antioxidant, peroxiredoxin-1 (PRDX-1), in the shortest surviving patients. Expression of PRDX-1 was associated with significantly reduced products of oxidative stress. Furthermore, NG2 expressing GBM cells showed resistance to ionising radiation (IR), rapidly recognised DNA damage and effectuated cell cycle checkpoint signalling. PRDX-1 knockdown transiently slowed tumour growth rates and sensitised them to IR in vivo. Our data establish NG2 as an important prognostic factor for GBM patient survival, by mediating resistance to radiotherapy through induction of ROS scavenging enzymes and preferential DNA damage signalling.

  6. Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

    SciTech Connect

    Adams, D.; et al.,

    2013-10-01

    A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.5--2.3 \\pi mm-rad horizontally and 0.6--1.0 \\pi mm-rad vertically, a horizontal dispersion of 90--190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

  7. Liquid chromatography with electrospray ionisation mass spectrometric detection of phenolic compounds from Olea europaea.

    PubMed

    Ryan, D; Robards, K; Prenzler, P; Jardine, D; Herlt, T; Antolovich, M

    1999-09-10

    The results demonstrate the potential of electrospray ionisation mass spectrometry for the specific detection of phenolic species in olives. Phenolic compounds were detected with greater sensitivity in the negative ion mode, but results from positive and negative ion modes were complementary with the positive ion mode showing structurally significant fragments. This is demonstrated by the identification of oleuropein and isomers of verbascoside. The structure of the latter were confirmed by retention, mass spectral and nuclear magnetic resonance data. These isomers have not previously been reported in olive.

  8. The WISSH quasars project. I. Powerful ionised outflows in hyper-luminous quasars

    NASA Astrophysics Data System (ADS)

    Bischetti, M.; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Sani, E.; Marconi, A.; Duras, F.; Zappacosta, L.; Brusa, M.; Comastri, A.; Cresci, G.; Feruglio, C.; Giallongo, E.; La Franca, F.; Mainieri, V.; Mannucci, F.; Martocchia, S.; Ricci, F.; Schneider, R.; Testa, V.; Vignali, C.

    2017-02-01

    Models and observations suggest that both the power and effects of AGN feedback should be maximised in hyper-luminous (LBol > 1047 erg s-1) quasars, i.e. objects at the brightest end of the AGN luminosity function. In this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of WISE/SDSS selected hyper-luminous (WISSH) broad-line quasars at z ≈ 1.5-5. The WISSH quasars project has been designed to reveal the most energetic AGN-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme AGN luminosities, i.e. LBol 1047 - 1048 erg s-1. We present near-infrared, long-slit LBT/LUCI1 spectroscopy of five WISSH quasars at z ≈ 2.3 - 3.5, showing prominent [OIII] emission lines with broad (FWHM 1200-2200 km s-1) and skewed profiles. The luminosities of these broad [OIII] wings are the highest measured so far, with L[OIII]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates Ṁ ≳ 1700M⊙ yr-1 and kinetic powers Ėkin ≳ 1045 erg s-1. Although these estimates are affected by large uncertainties because of the use of [OIII] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the AGN is highly efficient at pushing large amounts of ionised gas outwards. Furthermore, the mechanical outflow luminosities measured for WISSH quasars correspond to higher percentages ( 1-3%) of LBol than those derived for AGN with lower LBol. Our targets host very massive (MBH ≳ 2 × 109M⊙) black holes that are still accreting at a high rate (i.e. a factor of 0.4-3 of the Eddington limit). These findings clearly demonstrate that WISSH quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (SMBH) mass functions and revealing

  9. Forensic applications of desorption electrospray ionisation mass spectrometry (DESI-MS).

    PubMed

    Morelato, Marie; Beavis, Alison; Kirkbride, Paul; Roux, Claude

    2013-03-10

    Desorption electrospray ionisation mass spectrometry (DESI-MS) is an emerging analytical technique that enables in situ mass spectrometric analysis of specimens under ambient conditions. It has been successfully applied to a large range of forensically relevant materials. This review assesses and highlights forensic applications of DESI-MS including the analysis and detection of illicit drugs, explosives, chemical warfare agents, inks and documents, fingermarks, gunshot residues and drugs of abuse in urine and plasma specimens. The minimal specimen preparation required for analysis and the sensitivity of detection achieved offer great advantages, especially in the field of forensic science. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

  10. Skin dose measurements using radiochromic films, TLDS and ionisation chamber and comparison with Monte Carlo simulation.

    PubMed

    Alashrah, Saleh; Kandaiya, Sivamany; Maalej, Nabil; El-Taher, A

    2014-12-01

    Estimation of the surface dose is very important for patients undergoing radiation therapy. The purpose of this study is to investigate the dose at the surface of a water phantom at a depth of 0.007 cm as recommended by the International Commission on Radiological Protection and International Commission on Radiation Units and Measurement with radiochromic films (RFs), thermoluminescent dosemeters and an ionisation chamber in a 6-MV photon beam. The results were compared with the theoretical calculation using Monte Carlo (MC) simulation software (MCNP5, BEAMnrc and DOSXYZnrc). The RF was calibrated by placing the films at a depth of maximum dose (d(max)) in a solid water phantom and exposing it to doses from 0 to 500 cGy. The films were scanned using a transmission high-resolution HP scanner. The optical density of the film was obtained from the red component of the RGB images using ImageJ software. The per cent surface dose (PSD) and percentage depth dose (PDD) curve were obtained by placing film pieces at the surface and at different depths in the solid water phantom. TLDs were placed at a depth of 10 cm in a solid water phantom for calibration. Then the TLDs were placed at different depths in the water phantom and were exposed to obtain the PDD. The obtained PSD and PDD values were compared with those obtained using a cylindrical ionisation chamber. The PSD was also determined using Monte Carlo simulation of a LINAC 6-MV photon beam. The extrapolation method was used to determine the PSD for all measurements. The PSD was 15.0±3.6% for RF. The TLD measurement of the PSD was 16.0±5.0%. The (0.6 cm(3)) cylindrical ionisation chamber measurement of the PSD was 50.0±3.0%. The theoretical calculation using MCNP5 and DOSXYZnrc yielded a PSD of 15.0±2.0% and 15.7±2.2%. In this study, good agreement between PSD measurements was observed using RF and TLDs with the Monte Carlo calculation. However, the cylindrical chamber measurement yielded an overestimate of the PSD

  11. Characterisation of the muon beams for the Muon Ionisation Cooling Experiment

    NASA Astrophysics Data System (ADS)

    Adams, D.; Adey, D.; Alekou, A.; Apollonio, M.; Asfandiyarov, R.; Back, J.; Barber, G.; Barclay, P.; de Bari, A.; Bayes, R.; Bayliss, V.; Bertoni, R.; Blackmore, V. J.; Blondel, A.; Blot, S.; Bogomilov, M.; Bonesini, M.; Booth, C. N.; Bowring, D.; Boyd, S.; Bradshaw, T. W.; Bravar, U.; Bross, A. D.; Capponi, M.; Carlisle, T.; Cecchet, G.; Charnley, G.; Cobb, J. H.; Colling, D.; Collomb, N.; Coney, L.; Cooke, P.; Courthold, M.; Cremaldi, L. M.; DeMello, A.; Dick, A. J.; Dobbs, A.; Dornan, P.; Fayer, S.; Filthaut, F.; Fish, A.; Fitzpatrick, T.; Fletcher, R.; Forrest, D.; Francis, V.; Freemire, B.; Fry, L.; Gallagher, A.; Gamet, R.; Gourlay, S.; Grant, A.; Graulich, J. S.; Griffiths, S.; Hanlet, P.; Hansen, O. M.; Hanson, G. G.; Harrison, P.; Hart, T. L.; Hartnett, T.; Hayler, T.; Heidt, C.; Hills, M.; Hodgson, P.; Hunt, C.; Iaciofano, A.; Ishimoto, S.; Kafka, G.; Kaplan, D. M.; Karadzhov, Y.; Kim, Y. K.; Kolev, D.; Kuno, Y.; Kyberd, P.; Lau, W.; Leaver, J.; Leonova, M.; Li, D.; Lintern, A.; Littlefield, M.; Long, K.; Lucchini, G.; Luo, T.; Macwaters, C.; Martlew, B.; Martyniak, J.; Middleton, S.; Moretti, A.; Moss, A.; Muir, A.; Mullacrane, I.; Nebrensky, J. J.; Neuffer, D.; Nichols, A.; Nicholson, R.; Nugent, J. C.; Onel, Y.; Orestano, D.; Overton, E.; Owens, P.; Palladino, V.; Palmer, R. B.; Pasternak, J.; Pastore, F.; Pidcott, C.; Popovic, M.; Preece, R.; Prestemon, S.; Rajaram, D.; Ramberger, S.; Rayner, M. A.; Ricciardi, S.; Richards, A.; Roberts, T. J.; Robinson, M.; Rogers, C.; Ronald, K.; Rubinov, P.; Rucinski, R.; Rusinov, I.; Sakamoto, H.; Sanders, D. A.; Santos, E.; Savidge, T.; Smith, P. J.; Snopok, P.; Soler, F. J. P.; Stanley, T.; Summers, D. J.; Takahashi, M.; Tarrant, J.; Taylor, I.; Tortora, L.; Torun, Y.; Tsenov, R.; Tunnell, C. D.; Vankova, G.; Verguilov, V.; Virostek, S. P.; Vretenar, M.; Walaron, K.; Watson, S.; White, C.; Whyte, C. G.; Wilson, A.; Wisting, H.; Zisman, M. S.

    2013-10-01

    A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/ c, have emittances of approximately 1.2-2.3 π mm-rad horizontally and 0.6-1.0 π mm-rad vertically, a horizontal dispersion of 90-190 mm and momentum spreads of about 25 MeV/ c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE.

  12. EVOLUTION OF THE IEC AND EN STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION.

    PubMed

    Voytchev, M; Behrens, R; Ambrosi, P; Radev, R; Chiaro, P

    2016-09-01

    This article presents the evolution of the International Electrotechnical Commission (IEC) and the European standards for individual monitoring of ionising radiation issued, respectively, from the committees IEC/Sub Committee 45B and European Committee for Electro-technical Standardization/Technical Committee 45B 'Radiation protection instrumentation'. Standards for passive individual photon and beta dosimetry systems as well as those for active individual monitors are discussed. A neutron ambient dose equivalent (rate) meter standard and a technical report concerning the determination of uncertainty in measurement are also covered. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Derivatisation and gas chromatography-chemical ionisation mass spectrometry of selected synthetic and natural endocrine disruptive chemicals.

    PubMed

    Lerch, Oliver; Zinn, Peter

    2003-03-28

    Methods for ultra trace detection of endocrine disruptive chemicals (EDCs) are needed because of their low levels of impact. Twenty-one EDCs were selected, including 17beta-estradiol, 17alpha-ethinylestradiol, 17beta-testosterone and bisphenol A. Derivatisation with eight different fluorine containing compounds was examined. All EDCs could be derivatised automatedly (autosampler) with heptafluorobutyric acid (HFB) anhydride and trifluoroacetic acid (TFA) anhydride, respectively. The detection of these HFB and TFA derivatives in different chemical ionisation modes was studied. Fourteen different reagent gases, including methane, ammonia, acetone and water, were tested with the HFB and TFA derivatives in the negative chemical ionisation mode. Furthermore both types of derivatives were measured in positive chemical ionisation mode. Methane or water provide a good detection of all 21 TFA derivatives and create mass spectra with few fragmentation and characteristic mass peaks. This could serve as a basis for tandem or multiple mass spectrometric measurements.

  14. Using photo-ionisation models to derive carbon and oxygen gas-phase abundances in the rest UV

    NASA Astrophysics Data System (ADS)

    Pérez-Montero, Enrique; Amorín, Ricardo

    2017-01-01

    We present a new method to derive oxygen and carbon abundances using the ultraviolet (UV) lines emitted by the gas-phase ionised by massive stars. The method is based on the comparison of the nebular emission-line ratios with those predicted by a large grid of photo-ionisation models. Given the large dispersion in the O/H - C/O plane, our method firstly fixes C/O using ratios of appropriate emission lines and, in a second step, calculates O/H and the ionisation parameter from carbon lines in the UV. We find abundances totally consistent with those provided by the direct method when we apply this method to a sample of objects with an empirical determination of the electron temperature using optical emission lines. The proposed methodology appears as a powerful tool for systematic studies of nebular abundances in star-forming galaxies at high redshift.

  15. A rapid ex vivo tissue model for optimising drug detection and ionisation in MALDI imaging studies.

    PubMed

    Huber, K; Aichler, M; Sun, N; Buck, A; Li, Z; Fernandez, I E; Hauck, S M; Zitzelsberger, H; Eickelberg, O; Janssen, K P; Keller, U; Walch, A

    2014-10-01

    The aim of this study was to establish an ex vivo model for a faster optimisation of sample preparation procedures, for example matrix choice, in matrix-assisted laser desorption/ionisation (MALDI) drug imaging studies. The ionisation properties of four drugs, afatinib, erlotinib, irinotecan and pirfenidone, were determined in an ex vivo tissue experiment by spotting decreasing dilution series onto liver sections. Hereby, the drug signals were distinctly detectable using different matrix compounds, which allowed the selection of the optimal matrix for each drug. The analysis of afatinib and erlotinib yielded high drug signals with α-cyano-4-hydroxycinnamic acid matrix, whereas 2,3-dihydroxybenzoic acid was identified as optimal matrix for irinotecan and pirfenidone detection. Our method was validated by a MALDI drug imaging approach of in vivo treated mouse tissue resulting in corresponding findings, indicating the spotting method as an appropriate approach to determine the matrix of choice. The present study shows the accordance between the detection of ex vivo spotted drugs and in vivo administered drugs by MALDI-TOF and MALDI-FT-ICR imaging, which has not been demonstrated so far. Our data suggest the ex vivo tissue spotting method as an easy and reliable model to optimise MALDI imaging measurements and to predict drug detection in tissue sections derived from treated mice prior to the recruitment of laboratory animals, which helps to save animals, time and costs.

  16. An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal).

    PubMed

    Zagorodskikh, S; Vapa, M; Vahtras, O; Zhaunerchyk, V; Mucke, M; Eland, J H D; Squibb, R J; Linusson, P; Jänkälä, K; Ågren, H; Feifel, R

    2016-01-28

    Core-valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique. We use this molecule as a testbed for analyzing core-valence spectra by means of quantum chemical calculations of transition energies. These theoretical approaches range from two simple models, one based on orbital energies corrected by core valence interaction and one based on the equivalent core approximation, to a systematic series of quantum chemical electronic structure methods of increasing sophistication. The two simple models are found to provide a fast orbital interpretation of the spectra, in particular in the low energy parts, while the coverage of the full spectrum is best fulfilled by correlated models. CASPT2 is the most sophisticated model applied, but considering precision as well as computational costs, the single and double excitation configuration interaction model seems to provide the best option to analyze core-valence double hole spectra.

  17. Gas chromatography with diode array detection in series with flame ionisation detection.

    PubMed

    Gras, Ronda; Luong, Jim; Shellie, Robert A

    2017-06-02

    We introduce a gas chromatography detection approach that uses diode array detection operated in series with flame ionisation detection and demonstrate the utility of the detection approach for determination of volatile organic compounds. Diode array detection brings ultraviolet - visible spectroscopy (over a range of 190-640nm) onto the capillary gas chromatography time-scale, where average peak widths of analytes are on the order of 3-5s. The non-destructive nature of the diode array detector affords serially-coupled flame ionisation detection. This arrangement delivers near-simultaneous selective and universal detection without incurring additional analytical time, and without recourse to column flow splitting. The hyphenated technique is shown to be effective for chromatographic applications spanning an equivalent volatility range from C1 to C7n-paraffin hydrocarbons. The approach introduced herein provides increased sensitivity and selectivity for classes of compounds amenable to electronic spectroscopy such as alkenes, dienes, sulfurs, and aromatic compounds. The approach is demonstrated for direct measurement of carbon disulfide in work place atmospheres with a detection limit of 93pg on column and for the direct measurement of 1,3-butadiene in hydrocarbon matrices and ambient air with a detection of 73pg on column, each in less than 5min. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Measuring technique for thermal ionisation mass spectrometry of human tracer kinetic study with stable cerium isotopes.

    PubMed

    Keiser, Teresa; Höllriegl, Vera; Giussani, Augusto; Oeh, Uwe

    2011-06-01

    Thermal ionisation mass spectrometry (TIMS) method has been developed for the simultaneous detection of different cerium isotopes in biological samples (i.e., blood and urine) at very low concentrations. The work has been done in the frame of a biokinetic study, where different stable cerium isotopes have been administered orally and intravenously as tracers to the human body. In order to develop an appropriate detection method for the tracers in the biological samples, an optimum sample preparation technique has been set and adapted to the specific requirements of the analysis technique used, i.e., TIMS. For sample evaporation and ionisation, the double tantalum filament technique showed the best results. The ions produced were simultaneously collected on a secondary electron multiplier so that the isotopic ratios of the cerium isotopes in the biological samples could be measured. The technique has been optimised for the determination of cerium down to 1 ng loaded on the evaporation filament corresponding to cerium concentrations of down to 1 ng ml(-1) in the blood or urine samples. It has been shown that the technique is reliable in application and enables studies on cerium metabolism and biokinetics in humans without employing radioactive tracers.

  19. The effect of non ionising electromagnetic radiation on RAAF personnel during World War II.

    PubMed

    Flaherty, J A

    1994-05-01

    Did exposure to non ionising electromagnetic radiation during World War II in the short term have a stimulating effect on the anterior pituitary gland, and in turn on the gonads of both sexes, since the figures obtained appeared to affect the sexes equally? Is it that the long-term effect of microwave radiation on personnel is to cause adenoma and carcinoma? Is this long-term effect similar to the long-term effect of X-rays on infants, children and adolescents? According to Harrison's Principles of Internal Medicine 1980 (page 1710): "X-rays to the head and neck in infancy, childhood or adolescence is associated with a high incidence of thyroid disease later in life. Nodular disease is found to be particularly common on 20% of patients at risk, and may not be apparent until 30 years or more after exposure. One-third of the nodular type are found to be carcinomatous." The effect of non ionising electromagnetic and microwave radiation on those who work in these fields certainly needs much more investigation. What will be the long-term effect of using micro-ovens on the rising generation?

  20. Adaptive response to ionising radiation induced by cadmium in zebrafish embryos.

    PubMed

    Choi, V W Y; Ng, C Y P; Kong, M K Y; Cheng, S H; Yu, K N

    2013-03-01

    An adaptive response is a biological response where the exposure of cells or animals to a low priming exposure induces mechanisms that protect the cells or animals against the detrimental effects of a subsequent larger challenging exposure. In realistic environmental situations, living organisms can be exposed to a mixture of stressors, and the resultant effects due to such exposures are referred to as multiple stressor effects. In the present work we demonstrated, via quantification of apoptosis in the embryos, that embryos of the zebrafish (Danio rerio) subjected to a priming exposure provided by one environmental stressor (cadmium in micromolar concentrations) could undergo an adaptive response against a subsequent challenging exposure provided by another environmental stressor (alpha particles). We concluded that zebrafish embryos treated with 1 to 10 μM Cd at 5 h postfertilisation (hpf) for both 1 and 5 h could undergo an adaptive response against subsequent ~4.4 mGy alpha-particle irradiation at 10 hpf, which could be interpreted as an antagonistic multiple stressor effect between Cd and ionising radiation. The zebrafish has become a popular vertebrate model for studying the in vivo response to ionising radiation. As such, our results suggested that multiple stressor effects should be carefully considered for human radiation risk assessment since the risk may be perturbed by another environmental stressor such as a heavy metal.

  1. Characterisation of PRESAGE: A new 3-D radiochromic solid polymer dosemeter for ionising radiation.

    PubMed

    Adamovics, J; Maryanski, M J

    2006-01-01

    For the past 50 years there has been interest in developing 3-D dosemeters for ionising radiation. Particular emphasis has been put on those dosemeters that change their optical properties in proportion to the absorbed dose. Many of the dosemeters that have been evaluated have had limitations such as lack of transparency, diffusion of the image of the dose distribution or poor stability of baseline optical density. Many of these performance limitations have been overcome by the development of PRESAGE, an optically clear polyurethane-based radiochromic 3-D dosemeter. The solid PRESAGE dosemeter is formulated with a free radical initiator and a leuco dye and it does not require a container to maintain its shape. The polyurethane matrix is tissue equivalent and prevents the diffusion of the dose distribution image. There is a linear dose-response, which is independent of both photon energy and dose rate. Simple precautions such as preventing long-term exposure to additional ionising radiation including ultraviolet and controlling storage temperatures prevent the bleaching of the radiochromic response field within the irradiated dosemeter.

  2. High-resolution laser spectroscopy with the Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN-ISOLDE

    NASA Astrophysics Data System (ADS)

    Cocolios, T. E.; de Groote, R. P.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Day Goodacre, T.; Farooq-Smith, G. J.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heylen, H.; Kron, T.; Li, R.; Lynch, K. M.; Marsh, B. A.; Neyens, G.; Rossel, R. E.; Rothe, S.; Smith, A. J.; Stroke, H. H.; Wendt, K. D. A.; Wilkins, S. G.; Yang, X.

    2016-06-01

    The Collinear Resonance Ionisation Spectroscopy (CRIS) experiment at CERN has achieved high-resolution resonance ionisation laser spectroscopy with a full width at half maximum linewidth of 20(1) MHz for 219,221 Fr, and has measured isotopes as short lived as 5 ms with 214 Fr. This development allows for greater precision in the study of hyperfine structures and isotope shifts, as well as a higher selectivity of single-isotope, even single-isomer, beams. These achievements are linked with the development of a new laser laboratory and new data-acquisition systems.

  3. Correlation of the ionisation response at selected points of IC sensitive regions with SEE sensitivity parameters under pulsed laser irradiation

    SciTech Connect

    Gordienko, A V; Mavritskii, O B; Egorov, A N; Pechenkin, A A; Savchenkov, D V

    2014-12-31

    The statistics of the ionisation response amplitude measured at selected points and their surroundings within sensitive regions of integrated circuits (ICs) under focused femtosecond laser irradiation is obtained for samples chosen from large batches of two types of ICs. A correlation between these data and the results of full-chip scanning is found for each type. The criteria for express validation of IC single-event effect (SEE) hardness based on ionisation response measurements at selected points are discussed. (laser applications and other topics in quantum electronics)

  4. Effects of ionised or chelated water-soluble mineral mixture supplementation on growth performance, nutrient digestibility, blood characteristics, meat quality and intestinal microbiota in broilers.

    PubMed

    Upadhaya, S D; Lee, B R; Kim, I H

    2016-04-01

    An experiment was conducted to study the effects of dietary supplementation of water-soluble ionised or chelated mineral mixture on growth performance, nutrient digestibility, blood characteristics, relative organ weight, meat quality and excreta microflora in broilers. A total of 408 Arbor Acres broilers (17 birds in 8 replicate pens) were randomly allocated into one of the following three treatments: (1) Control/basal diet (CON), (2) T1 (basal diet + 0.5% ionised mineral mixture solution, pH 3.0) and (3) T2 (basal diet + 0.5% chelated mineral mixture solution, pH 3.0). The body weight gain was greater and feed conversion ratio was lower in broilers supplemented with ionised or chelated mineral liquid complex compared to CON during the grower and overall phase of the experiment. No significant effect in the concentration of Ca and P in the blood was observed in birds supplemented with ionised or chelated mineral mixture solution. No adverse effects were observed in organ weight and meat quality with ionised or chelated mineral mixture supplementation. Regarding intestinal microbiota counts there was a reduction of Escherichia coli counts in the small intestine in ionised mineral supplemented birds. In the large intestine, E. coli as well as Salmonella populations were reduced in ionised mineral supplemented birds. In conclusion, ionised or chelated minerals have partial positive effects in improving growth performance and reducing pathogenic bacteria load in the gastro-intestinal tract.

  5. Analyse de l'intensité de fluorescence émise par une multicouche périodique sous rayonnement synchrotron. Application à l'étude de la répartition spatiale des éléments dans l'empilement

    NASA Astrophysics Data System (ADS)

    Bridou, F.; Cauchon, G.; Idir, M.

    2004-11-01

    L'analyse de l'intensité du rayonnement de fluorescence des multicouches périodiques en fonction des angles d'incidence ou d'émission, peut constituer une méthode de caractérisation non destructive capable de déterminer le profil de concentration en profondeur d'un élément donné, notamment au niveau des interfaces où ce profil influe considérablement sur les performances optiques dans le domaine X-UV. Le principe de la méthode consiste à exciter la fluorescence d'un des deux matériaux de l'empilement par une radiation d'énergie supérieure à celle du seuil d'absorption de l'élément considéré. Celui-ci va émettre son propre rayonnement à l'intérieur de la multicouche. La répartition d'intensité est modulée selon la distribution géométrique des sources de rayonnement (donc de l'élément excité) à l'intérieur de l'empilement. On présente ici les résultats qui ont pu êtres obtenus à partir du rayonnement d'une source synchrotron (SB3_LURE) pour étudier une multicouche Mo/Si de 50 périodes. On a pu ainsi exciter d'une part la fluorescence du silicium, puis celle du molybdène, et montrer que les informations obtenues sur la répartition des éléments dans la multicouche étaient complémentaires.

  6. Multidisciplinary approach to assess the sensitivity of dwarf tomato plants to low-LET ionising radiation

    NASA Astrophysics Data System (ADS)

    De Micco, Veronica; De Pascale, Stefania; Aronne, Giovanna; Paradiso, Roberta; Vitaglione, Paola; Turano, Mimmo; Arena, Carmen

    Ionising radiation, acting alone or in interaction with microgravity and other environmental constraints, may affect plant at molecular, morpho-structural and physiological level. The intensity of the plant’s response depends on the properties of radiation and on the features of the plant itself. Indeed, different species are characterised by different susceptibility to radiation which may change during the life course. The aim of this research was to study the radiosensitivity to low-LET ionising radiation of plants of dwarf tomato (Solanum lycopersicum L. ‘Microtom’) at two phenological phases (vegetative and reproductive), within the purpose of analysing plants for consideration as candidates for Bioregenerative Life Support Systems (BLSS) in Space. To pursue this objective, plants of the cultivar Microtom were irradiated with different doses of X-rays either at the stage of the second true leaf (VP - vegetative phase) or when at least one flower was blossomed (RP - reproductive phase). Plant’s response to ionising radiation was assessed through a multidisciplinary approach combining genetic analyses, ecophysiological measurements, morpho-anatomical characterisation of leaves and fruits, nutritional analyses of fruits. Growth, molecular and morpho-functional traits were measured during plant development up to fruiting in both VP and RP plant groups, and compared with non-irradiated control plants. Plant growth was monitored weekly recording parameters such as plant height, number of leaves, leaf area, flowering and fruiting rate. Potential DNA alterations were explored through Random Amplified Polymorphic DNA (RAPD) technique. The efficiency of the photosynthetic apparatus was evaluated by determining photosynthetic pigment composition, photochemistry and leaf gas exchanges. Leaf and fruit structure were analysed through light and epi-fluorescence microscopy. Leaf anatomical traits related to photosynthetic efficiency, and to structural radioprotection

  7. PFI-ZEKE photoelectron spectrum of CH2F2, ionisation potential and ionic fragmentation appearance potentials.

    PubMed

    Forysinski, Piotr W; Zielke, Philipp; Luckhaus, David; Signorell, Ruth

    2010-04-07

    The first vibrationally resolved pulsed-field-ionisation zero-kinetic-energy (PFI-ZEKE) photoelectron spectrum of difluoromethane from its adiabatic ionisation potential (formation of the C(2v) conformer of CH(2)F(2)(+)) to the onset of the first ionic fragmentation channel is presented. Precise values for the adiabatic ionisation potential (12.7252 +/- 0.0009 eV) and the appearance potentials of the H loss product (13.065 +/- 0.003 eV) and the F loss product (14.30 +/- 0.06 eV) of the cation are reported. Ab initio harmonic calculations were performed at the MP2 level with quadruple-zeta basis sets in an attempt to assign the newly observed vibrational structure which, in its previously published low resolution form, led to numerous speculations regarding its true origin. The adiabatic ionisation potential and the fragmentation appearance potentials for the three lowest dissociation channels are also predicted in the complete basis set limit of CCSD(T) theory.

  8. Dosimetric aspects of film/screen mammography: in-phantom dosimetry with thimble-type ionisation chambers.

    PubMed

    Zoetelief, J; de Wit, N J; Broerse, J J

    1989-09-01

    The characteristics of 0.6 cm3 thimble-type Baldwin-Farmer (BF 2571) ionisation chambers for absorbed dose determinations in-phantom at mammography installations are investigated. The most important aspects for in-phantom dosimetry in mammography concern the conversion from air kerma to absorbed dose in mammary gland tissue, the energy dependence of the sensitivity of the ionisation chamber and the displacement correction factor for measurements in-phantom. Due to the considerable uncertainties in the elemental composition of the mammary glands the conversion from air kerma to absorbed dose in the mammary gland tissue has an uncertainty of the order of +/- 20%. The air kerma calibration factor of the BF-ionisation chamber is about 10% larger at mammography radiation qualities than at 300 kV x-rays or 137Cs gamma rays. For depths in excess of about 15 mm a displacement correction factor of 0.69 +/- 0.06 is derived for measurements with the BF 2571 chamber inside polymethylmethacrylate (PMMA) phantoms irradiated with 30 kV x-rays (first HVL:0.29 mm Al). The previously reported discrepancy between dose measurements with TLD and ionisation chambers at the entrance surface of a phantom for mammography radiation qualities is resolved and could be attributed to attenuation in the TLD encapsulation material.

  9. Hyphenation of atmospheric pressure chemical ionisation mass spectrometry to supercritical fluid chromatography for polar car lubricant additives analysis.

    PubMed

    Lavison-Bompard, Gwenaelle; Thiébaut, Didier; Beziau, Jean-François; Carrazé, Bernadette; Valette, Pascale; Duteurtre, Xavier; Tabet, Jean-Claude

    2009-01-30

    Car lubricant additives are added to mineral or synthetic base stocks to improve viscosity and resistance to oxidation of the lubricant and to limit wear of engines. As they belong to various chemical classes and are added to a very complex medium, the base stock, their detailed chromatographic analysis is very difficult and time consuming. In a previous paper, it was demonstrated that supercritical fluid chromatography (SFC) allows the elution of common low-molecular-weight additives. Since their total resolution could not be achieved owing to the limited peak capacity of packed columns, the hyphenation of selective and informative detection methods such as atomic emission detection (AED) was required. Further to results obtained in SFC-AED, this work describes the hyphenation of SFC to atmospheric pressure chemical ionisation ion trap mass spectrometry (MS). SFC-MS hyphenation is detailed: temperature, flow rates of gas and mobile phase introduced in the source, position of the restrictor, ionisation additives and conditions of autotune are studied. Car lubricant monitoring requires negative and positive ionisation modes with or without the addition of ionisation auxiliary solvent according to the nature of additives. Moreover, when sensitivity is of major concern for a selected additive, the autotuning routine of the MS has to be performed in conditions as close as possible to analytical conditions, i.e. under subcritical conditions. Unambiguous identification and structure elucidation of several additives in formulated car lubricants are also presented.

  10. Ionisation in turbulent magnetic molecular clouds. I. Effect on density and mass-to-flux ratio structures

    NASA Astrophysics Data System (ADS)

    Bailey, Nicole D.; Basu, Shantanu; Caselli, Paola

    2017-05-01

    Context. Previous studies show that the physical structures and kinematics of a region depend significantly on the ionisation fraction. These studies have only considered these effects in non-ideal magnetohydrodynamic simulations with microturbulence. The next logical step is to explore the effects of turbulence on ionised magnetic molecular clouds and then compare model predictions with observations to assess the importance of turbulence in the dynamical evolution of molecular clouds. Aims: In this paper, we extend our previous studies of the effect of ionisation fractions on star formation to clouds that include both non-ideal magnetohydrodynamics and turbulence. We aim to quantify the importance of a treatment of the ionisation fraction in turbulent magnetised media and investigate the effect of the turbulence on shaping the clouds and filaments before star formation sets in. In particular, here we investigate how the structure, mass and width of filamentary structures depend on the amount of turbulence in ionised media and the initial mass-to-flux ratio. Methods: To determine the effects of turbulence and mass-to-flux ratio on the evolution of non-ideal magnetised clouds with varying ionisation profiles, we have run two sets of simulations. The first set assumes different initial turbulent Mach values for a fixed initial mass-to-flux ratio. The second set assumes different initial mass-to-flux ratio values for a fixed initial turbulent Mach number. Both sets explore the effect of using one of two ionisation profiles: step-like (SL) or cosmic ray only (CR-only). We compare the resulting density and mass-to-flux ratio structures both qualitatively and quantitatively via filament and core masses and filament fitting techniques (Gaussian and Plummer profiles). Results: We find that even with almost no turbulence, filamentary structure still exists although at lower density contours. Comparison of simulations shows that for turbulent Mach numbers above 2, there is

  11. Ionisation chamber containing boron as a neutron detector in medical accelerator fields.

    PubMed

    Zielczynski, M; Gryzinski, M A; Golnik, N; Tulik, P

    2007-01-01

    A combination of the recombination principle of H(10) measurements with the use of the ionisation chambers containing boron has been presented, in order to increase the relative sensitivity of the chamber to neutrons by a factor close to the radiation quality factor of photoneutrons. Three types of the chambers were investigated. Two of them were filled with BF(3) and the third one contained electrodes covered with B(4)C. All the chambers were placed in paraffin moderators. The response of the chambers was investigated, depending on gas pressure and polarising voltage. The results showed that it was possible to obtain nearly the same response of the chamber to H(10) for photons and neutrons in a restricted energy range; however, further investigations are needed to make an optimum design.

  12. Determination of potato glycoalkaloids using high-pressure liquid chromatography-electrospray ionisation/mass spectrometry.

    PubMed

    Matsuda, Fumio; Morino, Keiko; Miyazawa, Haruna; Miyashita, Masahiro; Miyagawa, Hisashi

    2004-01-01

    A method for quantifying two toxic glycoalkaloids, alpha-solanine and alpha-chaconine, in potato (Solanum tuberosum) tuber tissue was developed using HPLC-electrospray ionisation (ESI)/MS. Potato samples were extracted with 5% aqueous acetic acid, and the extracts were subjected directly to HPLC-ESI/MS after filtration. By determining the intensities of the protonated molecules of alpha-solanine (m/z 868) and alpha-chaconine (m/z 852) using selected ion monitoring (positive ion mode), a sensitive assay was attained with detection limits of 38 and 14 ppb for the two glycoalkaloids, respectively. The high sensitivity and selectivity of MS detection effectively reduced the time of analysis thus enabling a high throughput assay of glycoalkaloids in potato tubers.

  13. Laser Ablation/Ionisation Mass Spectrometry: Sensitive and Quantitative Chemical Depth Profiling of Solid Materials.

    PubMed

    Riedo, Andreas; Grimaudo, Valentine; Moreno-García, Pavel; Neuland, Maike B; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2016-01-01

    Direct quantitative and sensitive chemical analysis of solid materials with high spatial resolution, both in lateral and vertical direction is of high importance in various fields of analytical research, ranging from in situ space research to the semiconductor industry. Accurate knowledge of the chemical composition of solid materials allows a better understanding of physical and chemical processes that formed/altered the material and allows e.g. to further improve these processes. So far, state-of-the-art techniques such as SIMS, LA-ICP-MS or GD-MS have been applied for chemical analyses in these fields of research. In this report we review the current measurement capability and the applicability of our Laser Ablation/Ionisation Mass Spectrometer (instrument name LMS) for the chemical analysis of solids with high spatial resolution. The most recent chemical analyses conducted on various solid materials, including e.g. alloys, fossils and meteorites are discussed.

  14. Correlation of spectroscopic and biochemical assays post-ionising radiation exposure in human skin cell analogues

    NASA Astrophysics Data System (ADS)

    Meade, A. D.; Byrne, H. J.; Lyng, F. M.

    2005-06-01

    Raman spectroscopy, as an evaluation of the products of ionising radiation exposure in biological systems, has been utilised mainly in the evaluation of the impact of exposure in tissue, cellular constituents and live animals. It has also been recently demonstrated that Raman spectroscopy can demonstrate key spectroscopic changes in the live cell associated with significant apoptotic and necrotic chemical damage. The present preliminary work utilises Raman spectroscopy at 514.5 nm to evaluate the results of exposure to γ-rays in HaCaT cells from a Co-60 therapy source, in tandem with other biological assays. The results demonstrate that Raman spectral changes may be correlated with changes in the cell also identified in parallel biochemical assays.

  15. Ionisation density effects following optical excitation in LiF:Mg, Ti (TLD-100).

    PubMed

    Weiss, D; Horowitz, Y; Oster, L

    2007-01-01

    The TL signal following 5 eV photon excitation of previously irradiated and readout material has been studied as a function of ionisation density and various experimental parameters: (i) maximum temperature of the first readout; (ii) photon fluence; (iii) photon energy and (iv) beta ray dose. Following alpha particle irradiation, the ratio of the second-readout to first-readout TL signal, epsilon(alpha,) has been found to be 10-20 times higher than that following beta irradiation, indicative of the possibility of using the double ratio epsilon(alpha)/epsilon(beta) as a mixed-field discriminator. The beginning of an attempt to explain this unusual effect is offered in the framework of the track structure theory and kinetic modelling of the beta ray dose-response of the first and second readouts.

  16. X-ray reflection from black-hole accretion discs with a radially stratified ionisation

    NASA Astrophysics Data System (ADS)

    Svoboda, J.; Domcek, V.; Dovčiak, M.; Guainazzi, M.; Marinucci, A.

    2015-07-01

    Recent X-ray observations have suggested a very high compactness of coronae in Active Galactic Nuclei as well as in X-ray Binaries. The compactness of the source implies that the black-hole accretion disc irradiation is a strong function of radius. We will show how the X-ray spectra are modified assuming the radially stratified ionisation according to the illumination by a point-like source on the black-hole rotational axis. We will discuss how this affects the measurements of the other model parameters, such as spin and radial emissivity. We will show the application of this model to the recent XMM-Newton/NUSTAR data of an active galaxy MCG-6-30-15.

  17. Ruthenium versus platinum: interactions of anticancer metallodrugs with duplex oligonucleotides characterised by electrospray ionisation mass spectrometry.

    PubMed

    Groessl, Michael; Tsybin, Yury O; Hartinger, Christian G; Keppler, Bernhard K; Dyson, Paul J

    2010-06-01

    The binding of the ruthenium-based anticancer drug candidates KP1019, NAMI-A and RAPTA-T towards different double-stranded oligonucleotides was probed by electrospray ionisation mass spectrometry and compared with that of the widely used platinum-based chemotherapeutics cisplatin, carboplatin and oxaliplatin. It was found that the extent of adduct formation decreased in the following order: cisplatin > oxaliplatin > NAMI-A > RAPTA-T > carboplatin > KP1019. In addition to the characterisation of the adducts formed with the DNA models, the binding sites of the metallodrugs on the oligonucleotides were elucidated employing top-down tandem mass spectrometry and were found to be similar for all the metallodrugs studied, irrespective of the sequence of the oligonucleotide. A strong preference for guanine residues was established.

  18. Non-ionising radiation human exposure assessment near telecommunication devices in Croatia.

    PubMed

    Simunić, Dina

    2006-03-01

    This paper gives an overview of the regulatory acts in non-ionising radiation in the world, with a special emphasis on basic guidelines issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). ICNIRP Guidelines are implemented in many countries worldwide. Croatia has also implemented them indirectly through the European Recommendation 1999/519/EC. The Croatian regulatory acts include the Non-lonising Radiation Protection Act, Ordinance on Electromagnetic Fields (EMF) Protection, and the Ordinance on Basic Requirements for Devices which produce Optical Radiation and Measures for Optical Radiation Protection. Dosimetry and densitometry are compliant with relevant international and European standards. The paper presents an example of densitometric human exposure assessment in complex indoor exposure conditions. In spite of a high number of indoor and outdoor sources and the "worst-case exposure assessment", the results are within the limits defined by the Croatian EMF Ordinance.

  19. Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry of bacteriochlorophylls from Chlorobiaceae: characteristic fragmentations.

    PubMed

    Airs, Ruth L; Keely, Brendan J

    2002-01-01

    Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry/mass spectrometry (APCI-LC/MS/MS) has been applied to the study of bacteriochlorophylls c, d, and e of phototrophic prokaryotes. Cultures of Chlorobiaceae containing bacteriochlorophyll c, d or e were examined using a high-resolution high-performance liquid chromatography (HPLC) method and APCI-LC/MS/MS employing post-column addition of formic acid. The results reveal complex distributions of bacteriochlorophyll homologues, with some closely eluting species giving isobaric protonated molecules. On-line LC/MS/MS studies reveal characteristic fragment ions for bacteriochlorophylls c, d, and e. Fragmentations involving loss of the extended alkyl substituents that are unique to bacteriochlorophylls c, d and e and their derivatives have been rationalised by studying the phaeophorbides and the results applied to the direct study of the bacteriochlorophylls.

  20. CF3(+) and CF2H(+): new reagents for n-alkane determination in chemical ionisation reaction mass spectrometry.

    PubMed

    Blake, Robert S; Ouheda, Saleh A; Evans, Corey J; Monks, Paul S

    2016-11-28

    Alkanes provide a particular analytical challenge to commonly used chemical ionisation methods such as proton-transfer from water owing to their basicity. It is demonstrated that the fluorocarbon ions CF3(+) and CF2H(+), generated from CF4, as reagents provide an effective means of detecting light n-alkanes in the range C2-C6 using direct chemical ionisation mass spectrometry. The present work assesses the applicability of the reagents in Chemical Ionisation Mass Spectrometric (CI-TOF-MS) environments with factors such as high moisture content, operating pressures of 1-10 Torr, accelerating electric fields (E/N) and long-lived intermediate complex formation. Of the commonly used chemical ionisation reagents, H3O(+) and NO(+) only react with hexane and higher while O2(+) reacts with all the target samples, but creates significant fragmentation. By contrast, CF3(+) and CF2H(+) acting together were found to produce little or no fragmentation. In dry conditions with E/N = 100 Td or higher the relative intensity of CF2H(+) to CF3(+) was mostly less than 1% but always less than 3%, making CF3(+) the main reagent ion. Using O2(+) in a parallel series of experiments, a substantially greater degree of fragmentation was observed. The detection sensitivities of the alkanes with CF3(+) and CF2H(+), while relatively low, were found to be better than those observed with O2(+). Experiments using alkane mixtures in the ppm range have shown the ionisation technique based on CF3(+) and CF2H(+) to be particularly useful for measurements of alkane/air mixtures found in polluted environments. As a demonstration of the technique's effectiveness in complex mixtures, the detection of n-alkanes in a smoker's breath is demonstrated.

  1. Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

    NASA Astrophysics Data System (ADS)

    Bannan, T.; Booth, M.; Benyezzar, M.; Bacak, A.; Alfarra, M. R. R.; Topping, D. O.; Percival, C.

    2015-12-01

    Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

  2. Resonance ionisation mass spectrometry of krypton and its applications in planetary science

    NASA Astrophysics Data System (ADS)

    Strashnov, I.; Gilmour, J. D.

    2014-06-01

    A new resonance ionisation time-of-flight mass spectrometer for determining krypton isotope ratios in extraterrestrial samples is presented. Laser heating is used to extract gas from mg-size samples. A cryogenic sample concentrator is employed. Atoms continuously condense on a 75 K stainless steel substrate at the back plate of a Wiley-McLaren laser ion source from where they are desorbed by a pulsed 1064 nm laser and resonantly ionized in the plume. A three-colour (116.5 nm, 558.1 nm and 1064 nm) excitation scheme is used. Tuneable coherent Vacuum Ultraviolet (vuv) radiation near 116.5 nm is generated by four-wave sum frequency mixing of 252.5 nm and 1507 nm pulsed dye laser beams in a binary mixture of negatively and positively dispersive gases (Xe and Ar). Isotope effects have been observed that reduce the reproducibility of isotope ratio measurements between odd-mass, non-zero nuclear spin isotopes and even-mass, zero nuclear spin isotopes. This can be minimised and stabilised by controlling the laser fluences, experimental geometry, and the population of the magnetic sub-levels of the excited atomic states used in the ionisation process. Once stability is achieved, sample-standard bracketing (during which the known isotope ratios of a standard are determined before and after the measurements of the sample under the same conditions) allows precision and reproducibility of 1 % for the major isotope ratios to be achieved in samples krypton atoms. Detection limits of atoms/isotope have been demonstrated, ratios of Kr in meteorites have been made with 5-10 % precision. Applications of the instrument in various areas of planetary science are also discussed.

  3. Computer modeling and experimental work on the astrobiological implications of the martian subsurface ionising radiation environment

    NASA Astrophysics Data System (ADS)

    Dartnell, Lewis R.

    Any microbial life extant in the top meters of the martian subsurface is likely to be held dormant for long periods of time by the current permafrost conditions. In this potential habitable zone, a major environmental hazard is the ionising radiation field generated by the flux of exogenous energetic particles: solar energetic protons and galactic cosmic rays. The research reported here constitutes the first multidisciplinary approach to assessing the astrobiological impact of this radiation on Mars. A sophisticated computer model has been constructed de novo to characterise this complex subsurface ionising radiation field and explore the influence of variation in crucial parameters such as atmospheric density, surface composition, and primary radiation spectra. Microbiological work has been conducted to isolate novel cold-tolerant bacterial strains from the Dry Valleys environment of Antarctica, an analogue site to the martian surface, and determine their phylogenetic diversity and survival under high-dose gamma-ray exposure frozen at -79 °C, a temperature characteristic of the martian mid-latitude permafrost. Original results are presented pertinent to microbial survival time, persistence of organic biomarkers, and calibration of the optically stimulated luminescence dating technique, as a function of depth. The model predicts a population of radiation resistant cells to survive in martian permafrost soil for 450,000 years at 2 m depth, the proposed drill length of the ExoMars rover. The Antarctic culturing studies identified representatives of four bacterial genera. The novel isolate Brevundimonas sp. MV.7 is found to show 99% 16S sequence similarity to cells discovered in NASA spacecraft assembly clean rooms, with the experimental irradiation determining this strain to suffer 10-6 population inactivation after a radiation dose of 7.5 kGy in martian permafrost conditions. Integrating the modelling and experimental irradiation, this research finds a contaminant

  4. A photo-ionised canopy for the shock-excited Criss-Cross nebula

    NASA Astrophysics Data System (ADS)

    Temporin, S.; Weinberger, R.; Stecklum, B.

    2007-05-01

    Aims:We study a new broad, well-defined arc of optical nebulosity close to the cloud-shock interacting Criss-Cross nebula, derive the basic physical properties of the nebulosity, and revise those of the nebula, and compare both objects to simulations of cloud-shock interactions from the literature. Methods: Deep optical, partly wide-field images were used to reveal the intricate morphology and overall extent of the nebulosities. Optical spectroscopy enabled us to uncover their nature. Results: The two nebulosities are obviously physically linked, but are of different types; the Criss-Cross nebula is, as was also shown in an earlier paper, excited via a slow shock from the expanding Orion-Eridanus bubble, but the broad arc is definitely photo-ionised. The source for ionising photons appears to be hot gas in this bubble. Some results of simulations of interactions of SNRs with interstellar clouds available from the literature bear a striking resemblance to our nebulae, which appear to represent an example - unrivalled in closeness and clarity - of an early-to-medium stage in the destruction of an isolated cloud over-run by a highly evolved SNR. Thereby the Criss-Cross nebula is, when seen from the SNR, the rear disrupted part of the original, small cloud, whereas the arc is probably its still rather intact front part. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  5. Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

    NASA Astrophysics Data System (ADS)

    Bannan, Thomas; Booth, A. Murray; Alfarra, Rami; Bacak, Asan; Pericval, Carl

    2016-04-01

    Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

  6. The use of particle beam mass spectrometry for the measurement of impurities in a nabumetone drug substance, not easily amenable to atmospheric pressure ionisation techniques.

    PubMed

    Wolff, J C; Hawtin, P N; Monté, S; Balogh, M; Jones, T

    2001-01-01

    Liquid chromatography/particle beam mass spectrometry (LC/PB-MS) was used for the structural elucidation of some impurities in nabumetone as this compound poorly ionises by atmospheric pressure ionisation (API) techniques. PB-MS was optimised for nabumetone and a sensitivity study was carried out. To obtain full scan electron ionisation spectra a minimum of 100 ng of compound on column was needed. By using 20 mg/mL solutions of nabumetone, impurities at levels of about 250 ppm mass fraction relative to nabumetone could be detected. Results were compared with LC/API-MS and previous GC/MS.

  7. The detection of photodegradation products of irinotecan (CPT-11, Campto, Camptosar), in clinical studies, using high-performance liquid chromatography/atmospheric pressure chemical ionisation/mass spectrometry.

    PubMed

    Dodds, H M; Robert, J; Rivory, L P

    1998-08-01

    A method for the detection of the photodegradation products of irinotecan (CPT-11, Campto, Camptosar) was developed using high-performance liquid chromatography (HPLC) with fluorescence detection and HPLC/atmospheric pressure chemical ionisation/mass spectrometry (HPLC/APCI/MS). Remnants of infusion solution as well as samples of urine and plasma collected at the end of the infusion of CPT-11 to cancer patients were screened for the five principal known photodegradation products (PDPs) of CPT-11. The concurrent use of standards of the PDPs with ion-extract HPLC/APCI/MS chromatograms enabled the identification of trace quantities of two PDPs in most samples analysed. However, similar analyses of fresh clinical drug solutions revealed that the PDPs were not generated significantly by exposure to light during the infusion period, but were already present in the drug ampoules. Furthermore, this appears to be the source of traces of PDPs detectable in urine and plasma of patients rather than metabolism, per se.

  8. Standardisation of (90)Y and determination of calibration factors for (90)Y microspheres (resin) for the NPL secondary ionisation chamber and a Capintec CRC-25R.

    PubMed

    Ferreira, Kelley M; Fenwick, Andrew J; Arinc, Arzu; Johansson, Lena C

    2016-03-01

    The use of (90)Y resin microspheres (SIR-Spheres® microspheres) in Nuclear Medicine has dramatically increased in recent years due to its favourable outcome in the treatment of liver cancer and liver metastases (Rajekar et al., 2011). The measurement of administered activity before and residual activity after treatment in radionuclide calibrators is required to determine total activity delivered to the patient. In comparison with External Beam Radiotherapy (EBRT) where administered doses are often know to within ±5%, the actual administered activity in nuclear medicine procedures may only be known to within ±20% and subsequent dose calculations can result in even larger uncertainties (Fenwick et al., 2009). It is a well-recognised issue that ion chambers are instruments that are sensitive to the measurement geometry and matrix of a source, in particular for pure beta or low energy (<100keV) x-ray emitters (Gadd et al., 2006). This paper presents new calibration factors for NPL secondary standard ionisation chamber system (Vinten 671) and a Capintec CRC-25R radionuclide calibrator along with a discussion of the measurement problems associated with this radionuclide and matrix. Calibration of the NPL secondary standard system for this measurement matrix will enable NPL to provide standards for the Nuclear Medicine community and consequently increase the measurement capability.

  9. Efficiency of generation of highly ionised atoms under resonance absorption of CO{sub 2}-laser radiation

    SciTech Connect

    Gus'kov, Sergei Yu; Demchenko, N N; Makarov, K N; Rozanov, Vladislav B; Satov, Yu A; Sharkov, Boris Yu

    2011-10-31

    We consider the generation of beams of highly ionised atoms in solid targets irradiated with CO{sub 2}-laser pulses. We present experimental results on generation of Mg and Pb ions from laser plasma at a radiation flux density q Almost-Equal-To 10{sup 14} W cm{sup -2}. We have developed a theoretical model describing the plasma heating by CO{sub 2}-laser radiation at a high pulse intensity on the target, taking into account the ponderomotive forces affecting the behaviour of the interaction of light with the plasma. It is shown that in the case of resonance absorption of laser radiation by the plasma, the efficiency of generation of highly ionised atoms of the target substance is higher than the efficiency of generation in the case of classical absorption. The results of the numerical calculation by the developed model are in good agreement with the experiment.

  10. Application of atmospheric pressure chemical ionisation mass spectrometry in the analysis of barbiturates by high-speed analytical countercurrent chromatography.

    PubMed

    Jones, Jonathan J; Kidwell, Huw; Games, David E

    2003-01-01

    Four barbiturates (barbital, allobarbital, phenobarbital and butalbital) were analysed using high-speed analytical countercurrent chromatography (HSACCC) and high-performance liquid chromatography (HPLC) interfaced with mass spectrometry, using negative mode atmospheric pressure chemical ionisation (APCI). The polar biphasic solvent system of butyronitrile/acetonitrile/water (1:1:1) was used, in the upper-stationary, lower-mobile mode of operation, at a flow rate of 1 mL/min and a rotational speed of 1200 rpm, equating to an applied "g"-field of 177 g. The fractional stationary phase retention (S(F)) was 0.58. Representative mass spectral data are presented from the HPLC and the HSACCC analyses. Structural information was obtained using source-induced fragmentation at increased source block voltages. The effect of increasing g-field on chromatographic resolution is illustrated using the binary base system of butyronitrile/water (1:1), under electrospray ionisation. Copyright 2003 John Wiley & Sons, Ltd.

  11. Fast nucleotide identification through fingerprinting using gold nanoparticle-based surface-assisted laser desorption/ionisation.

    PubMed

    Larguinho, Miguel; Capelo, José L; Baptista, Pedro V

    2013-02-15

    We report a method centred on gold nanoparticle-based surface-assisted laser desorption/ionisation for analysis of deoxynucleotides and alkylated nucleobases. Gold nanoparticles allow for enhanced analysis capability by eliminating undesired signature peaks; thus more elegant mass spectra can be attained that allow identification by nucleotide mass fingerprint. The resulting fingerprinting patterns on the spectra are compared and associated with the presence of different nucleotides in the sample. This method can be easily extended to modified nucleotides implicated in genome lesions due to exposure to environment chemicals, such as DNA adducts (e.g. guanine adducts). The use of gold nanoparticles for surface-assisted laser desorption/ionisation can be an useful tool to resolve common issues of background noise when analysing nucleic acids samples.

  12. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Evolution of tubular singular pulsed beams in a nonlinear dielectric medium upon ionisation

    NASA Astrophysics Data System (ADS)

    Vlasov, R. A.; Khasanov, O. Kh; Smirnova, T. V.

    2005-10-01

    The dynamics of a high-power femtosecond tubular pulsed beam in a dielectric medium is numerically analysed upon optically induced ionisation. It is found that the balance between nonlinearities of opposite sign and different magnitude in the case of multiphoton ionisation favours the establishment of a quasi-soliton regime of radiation propagation over a distance exceeding several diffraction lengths. The use of these beams enables attaining high-density light fields and generate high-density plasmas.

  13. Ionisation response in semiconductor structures exposed to the X-ray radiation of a femtosecond laser-plasma source

    NASA Astrophysics Data System (ADS)

    Chumakov, A. I.; Belova, M. P.; Kessarinsky, L. N.; Borisov, A. Ya; Ivanov, K. A.; Tsymbalov, I. N.; Volkov, R. V.; Savel'ev, A. B.; Galanina, L. I.; Chirskaya, N. P.; Novikov, L. S.

    2017-06-01

    The possibilities of applying a femtosecond laser-plasma source of X-ray radiation for modelling the effect of single nuclear particles based on the principle of equivalent charge generation are analysed. The parameters of femtosecond X-ray radiation for the experimental modelling of individual radiation effects are validated. The experimental setup forming the X-ray radiation is described. The results of comparative ionisation response modelling in simple electronic devices using the FLUKA and FEANT codes are presented.

  14. Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers.

    PubMed

    Dowdell, S; Tyler, M; McNamara, J; Sloan, K; Ceylan, A; Rinks, A

    2016-11-15

    Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm(2)-20  ×  20 cm(2) for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

  15. Potential errors in relative dose measurements in kilovoltage photon beams due to polarity effects in plane-parallel ionisation chambers

    NASA Astrophysics Data System (ADS)

    Dowdell, S.; Tyler, M.; McNamara, J.; Sloan, K.; Ceylan, A.; Rinks, A.

    2016-12-01

    Plane-parallel ionisation chambers are regularly used to conduct relative dosimetry measurements for therapeutic kilovoltage beams during commissioning and routine quality assurance. This paper presents the first quantification of the polarity effect in kilovoltage photon beams for two types of commercially available plane-parallel ionisation chambers used for such measurements. Measurements were performed at various depths along the central axis in a solid water phantom and for different field sizes at 2 cm depth to determine the polarity effect for PTW Advanced Markus and Roos ionisation chambers (PTW-Freiburg, Germany). Data was acquired for kilovoltage beams between 100 kVp (half-value layer (HVL)  =  2.88 mm Al) and 250 kVp (HVL  =  2.12 mm Cu) and field sizes of 3-15 cm diameter for 30 cm focus-source distance (FSD) and 4  ×  4 cm2-20  ×  20 cm2 for 50 cm FSD. Substantial polarity effects, up to 9.6%, were observed for the Advanced Markus chamber compared to a maximum 0.5% for the Roos chamber. The magnitude of the polarity effect was observed to increase with field size and beam energy but was consistent with depth. The polarity effect is directly influenced by chamber design, with potentially large polarity effects for some plane-parallel ionisation chambers. Depending on the specific chamber used, polarity corrections may be required for output factor measurements of kilovoltage photon beams. Failure to account for polarity effects could lead to an incorrect dose being delivered to the patient.

  16. Formation of 2-propanol in condensed molecular films of acetaldehyde following electron impact ionisation-induced proton transfer*

    NASA Astrophysics Data System (ADS)

    Borrmann, Tobias; Swiderek, Petra

    2016-06-01

    Experimental studies on thin condensed layers of acetaldehyde have previously revealed that electron exposure at an energy above the ionisation threshold leads to formation of 2-propanol. However, the mechanism of this reaction remained unclear. Therefore, a computational approach is used to explore the electron-induced reactions of acetaldehyde yielding 2-propanol. Starting from hydrogen-bonded dimers of acetaldehyde we show that the initial ionisation event triggers proton transfer between the two acetaldehyde moieties resulting in a hydrogen-bonded complex of a [OCCH3] radical and a protonated acetaldehyde cation. Given an excess energy of up to 0.75 eV and a favourable arrangement, a methyl radical released upon dissociation of the CC bond within the [OCCH3] radical can migrate to the carbonyl carbon of the protonated acetaldehyde cation. This produces a 2-propanol radical cation and CO. Neutral 2-propanol is then obtained by recombination with a second electron. A mechanism involving ionisation-driven proton transfer is thus proposed as pathway to the formation of 2-propanol during electron exposure of condensed layers of acetaldehyde.

  17. Investigation of the ionisation density dependence of the glow curve characteristics of LIF:MG,TI (TLD-100)

    PubMed Central

    Horowitz, Y. S.; Horowitz, A.; Oster, L.; Marino, S.; Datz, H.; Margaliot, M.

    2008-01-01

    The dependence of the shape of the glow curve of LiF:Mg,Ti (TLD-100) on ionisation density was investigated using irradiation with 90Sr/90Y beta rays, 60 and 250 kVp X rays, various heavy-charged particles and 0.2 and 14 MeV neutrons. Special attention is focused on the properties of high-temperature thermoluminescence; specifically, the behaviour of the high-temperature ratio (HTR) of Peaks 7 and 8 as a function of batch and annealing protocol. The correlation of Peaks 7 and 8 with average linear-energy-transfer (LET) is also investigated. The HTR of Peak 7 is found to be independent of LET for values of LET approximately >30 keV µm−1. The behaviour of the HTR of Peak 8 with LET is observed to be erratic, which suggests that applications using the HTR should separate the contributions of Peaks 7 and 8 using computerised glow curve deconvolution. The behaviour of the HTR following neutron irradiation is complex and not fully understood. The shape of composite Peak 5 is observed to be broader following high ionisation alpha particle irradiation, suggesting that the combined use of the HTR and the shape of Peak 5 could lead to improved ionisation density discrimination for particles of high LET. PMID:18667402

  18. Spectrometre de masse a ionisation Penning selective: Elimination des corrections necessaires a la determination du rapport isotopique de l'hydrogene

    NASA Astrophysics Data System (ADS)

    Letarte, Sylvain

    Dans le but d'ameliorer la precision avec laquelle le rapport isotopique de l'hydrogene peut etre determine, un spectrometre de masse a ionisation Penning a ete construit pour provoquer l'ionisation selective de l'hydrogene moleculaire et de l'hydrure de deuterium a partir d'un melange gazeux. L'utilisation d'atomes dans des etats d'excitation metastable s'est averee une solution adequate pour reponde a cette attente. L'emploi de l'helium, a l'interieur d'une source d'atomes metastables construit specifiquement pour ce travail, ne permet pas d'obtenir un spectre de masse compose uniquement des deux molecules d'interet. L'ionisation de ces dernieres provient de deux processus distincts, soient l'ionisation Penning et l'ionisation par bombardement electronique. Contrairement a l'helium, il a ete demontre que le neon metastable est un candidat ideal pour produire l'ionisation selective de type Penning. Le nombre d'ions produits est directement proportionnel au courant de la decharge electrique et de la pression d'operation de la source d'atomes metastables. Ces resultats demontrent le potentiel d'un tel spectrometre de masse pour ameliorer la precision a laquelle le rapport isotopique peut etre determine comparativement aux autres techniques existantes.

  19. Xpg limits the expansion of haematopoietic stem and progenitor cells after ionising radiation

    PubMed Central

    Avila, Alush I.; Illing, Anett; Becker, Friedrich; Maerz, Lars D.; Morita, Yohei; Philipp, Melanie; Burkhalter, Martin D.

    2016-01-01

    Reduced capacity of genome maintenance represents a problem for any organism, potentially causing premature death, carcinogenesis, or accelerated ageing. Strikingly though, loss of certain genome stability factors can be beneficial, especially for the maintenance of tissue stem cells of the intestine and the haematopoietic system. We therefore screened for genome stability factors negatively impacting maintenance of haematopoietic stem cells (HSC) in the context of ionising radiation (IR). We found that in vivo knock down of Xeroderma pigmentosum, complementation group G (Xpg) causes elevation of HSC numbers after IR treatment, while numbers of haematopoietic progenitors are elevated to a lesser extent. IR rapidly induces Xpg both on mRNA and on protein level. Prevention of this induction does not influence activation of the checkpoint cascade, yet attenuates late checkpoint steps such as induction of p21 and Noxa. This causes a leaky cell cycle arrest and lower levels of apoptosis, both contributing to increased colony formation and transformation rates. Xpg thus helps to adequately induce DNA damage responses after IR, thereby keeping the expansion of damaged cells under control. This represents a new function of Xpg in the response to IR, in addition to its well-characterized role in nucleotide excision repair. PMID:27137888

  20. Effect of penetrating ionising radiation on the mechanical properties of pericardium

    NASA Astrophysics Data System (ADS)

    Daar, Eman; Woods, E.; Keddie, J. L.; Nisbet, A.; Bradley, D. A.

    2010-07-01

    The pericardium is an anistropic composite material made up of collagen and elastin fibres embedded in an amorphous matrix mainly composed of proteoglycan and hyaluronan. The collagen fibres are arranged in layers, with different directions of alignment in each layer, giving rise to interesting mechanical properties of pericardium, including the ability to undergo large deformation during performance of regular physiological functions. The present study aims to investigate the effect of penetrating photon ionising radiation on bovine pericardium tissue, being part of a study of the effect of cardiac doses received in breast radiotherapy and the possibility that this can give rise to cardiovascular complications. Irradiation doses in the range 5-80 Gy were used. To characterise the various mechanical properties [elastic modulus, stress relaxation, ultimate tensile strength (UTS) and fracture] a uniaxial tensile test method was applied. The preliminary results reflect the wide inter-sample variations that are expected in dealing with tissues, with only a weak indication of increase in the UTS of the pericardium tissue with increase in radiation dose. Such an effect has also been observed by others, with reduction in UTS at doses of 80 Gy.

  1. 100 years of Cosmic Rays - from the ionisation of air to beyond the LHC

    NASA Astrophysics Data System (ADS)

    Watson, Alan

    2012-03-01

    The study of cosmic rays has impacted on many disciplines, including astrophysics, particle physics, carbon dating and radio astronomy: it has thus had scientific and societal impact. They were discovered in 1912 as a result of the efforts by some of the most distinguished scientists of that era, puzzled by their inability to explain the discharge of ionisation chambers. I will describe some of the early work that led, inter alia, to the discovery of the positron, the muon and the first strange particles and thus to the birth of particle physics. In 1938 it was found that showers of particles that arrive at the earth simultaneously are produced by primary cosmic rays of ˜10^15 eV, about 10^5 times more energetic than any particles that had been contemplated before. I will discuss how study of these showers has led to the discovery of cosmic rays of energies as great as 3 x 10^20 eV, challenging our understanding of where and how they are created. Data from the Pierre Auger Observatory, the largest cosmic-ray detector ever built, is now being used for astrophysical studies and to give glimpses of some hadronic physics at centre-of-mass energies more than 4 times greater than are accessible at the LHC.

  2. Variability in the H +3 emission of Saturn: Consequences for ionisation rates and temperature

    NASA Astrophysics Data System (ADS)

    Melin, Henrik; Miller, Steve; Stallard, Tom; Trafton, L. M.; Geballe, T. R.

    2007-01-01

    We present an analysis of observations of the auroral/polar regions of Saturn, carried out in 1999, 2004 and 2005, making use of the facility spectrometer, CGS4, on the United Kingdom Infrared Telescope (UKIRT), Mauna Kea, Hawaii. We obtain temperatures of 380(±70) K in 1999 and 420(±70) K in 2004. (The 2005 data has insufficient spectral resolution for a temperature determination to be made.) Our most probable interpretation is that the temperature of Saturn's auroral/polar H +3 layer should be taken as 400(±50) K. This is lower than the value obtained by Miller et al. [Miller, S., and 10 colleagues, 2000. Philos. Trans. R. Soc. 358, 2485-2502], which is shown to be in error. Our analysis reveals clearly that the line emission due to H +3 varies considerably, showing nearly an order of magnitude increase when one compares the data obtained in 1999 with those of 2004. Our conclusion is that this variability is (mainly) due to the changing H +3 column density. By analogy with modelling results obtained for Jupiter, we estimate that the particle (keV electron) precipitation experienced by Saturn must be ˜20 times greater in 2004 than in 1999, to produce this additional ionisation. The H +3 emission increases, but this is insufficient to offset most of the heating due to the extra particle precipitation, indicating that this ion does not act as a "thermostat" on Saturn, in the same way that it does on Jupiter.

  3. Resolving Ionisation and Metallicity on Parsec Scales Across Primordial Analogues with HST-WFC3

    NASA Astrophysics Data System (ADS)

    James, B. L.; Auger, M.; Calzetti, D.; Kewley, L.; Aloisi, A.; Pettini, M.; Trussler, J.

    2016-06-01

    Nearby Blue Compact Dwarf (BCD) galaxies are excellent laboratories for conducting detailed spatially resolved spectroscopic analyses of star-formation (SF), feedback, and chemical evolution in relatively pristine, low-metallicity environments analogous to those thought to exist in the early Universe. In this talk I will show a new, extensive dataset of narrow-band HST-WFC3 imaging where I essentially use HST as a high-spatial-resolution IFU to map six major emission lines in unprecedented detail, including HeII emission from WR stars. In this pioneering study, I spatially resolve diagnostic line ratios on sub-pc scales in two BCDs and deduce which ionisation mechanisms (e.g. shocks and/or photoionisation) are at work and assess their role in shaping the global galaxy properties. Moreover, I will present the first 'metallicity image' of a star-forming galaxy, revealing inhomogeneities on scales as small as <50~pc. This work not only demonstrates the benefits of high-resolution spatially-resolved observations in assessing the effects of feedback mechanisms and accurate chemical abundances, but also the limitations of emission line diagnostic tools which can break down on scales smaller than a H II region. Both aspects are especially relevant as we enter the era of extremely large telescopes, when observing structure on ˜~10~pc scales will no longer be limited to the local universe.

  4. Ionising radiation exposure in patients with circular frame treatment of distal tibial fractures.

    PubMed

    Bryant, H; Dearden, P M C; Harwood, P J; Wood, T J; Sharma, H K

    2015-08-01

    Total radiation exposure accumulated during circular frame treatment of distal tibial fractures was quantified in 47 patients treated by a single surgeon from February 2007 until Oct 2010. The radiation exposures for all relevant radiology procedures for the distal tibial injury were included to estimate the radiation risk to the patient. The median time of treatment in the frame was 169 days (range 105-368 days). Patients underwent a median of 13 sets of plain radiographs; at least one intra operative exposure and 16 patients underwent CT scanning. The median total effective dose per patient from time of injury to discharge was 0.025mSv (interquartile range 0.013-0.162 and minimum to maximum 0.01-0.53). The only variable shown to be an independent predictor of cumulative radiation dose on multivariate analysis was the use of CT scanning. This was associated with a 13-fold increase in overall exposure. Radiation exposure during treatment of distal tibial fractures with a circular frame in this group was well within accepted safe limits. The fact that use of CT was the only significant predictor of overall exposure serves as a reminder to individually assess the risk and utility of radiological investigations on an individual basis. This is consistent with the UK legal requirements for justification of all X-ray imaging, as set out in the Ionising Radiation (Medical Exposure) Regulations 2000 [1].

  5. Free energy for blue copper protein unfolding determined by electrospray ionisation mass spectrometry.

    PubMed

    Cunsolo, V; Foti, S; La Rosa, C; Saletti, R; Canters, G W; Verbeet, M P

    2001-01-01

    An electrospray ionisation (ESI) mass spectrometric method for the determination of the free energy (DeltaG) of unfolding of proteins is described. The method was tested using three blue copper proteins: wild type azurin, Cys-3Ala/Cys-26Ala (C3A/C26A) azurin mutant and wild-type amicyanin. The time course of the denaturation process of the proteins dissolved in methanol/water (50:50, v/v, pH 3.5) was followed by recording ESI mass spectra at time intervals. The spectra showed two series of peaks, corresponding to the native holo-protein and the unfolded apo-protein. From the intensity ratio of these two series of peaks at increasing time and at equilibrium, the free energy for the unfolding process for the three proteins could be determined. To evaluate the reliability of the thermodynamic data obtained by the ESI mass spectrometric approach, the denaturation process was followed by UV-VIS spectroscopy. The two sets of data obtained by these independent methods were in good agreement indicating that the ESI-MS approach can be used to obtain reliable quantitative information about the protein unfolding process. In principle, this approach can be applied to other proteins and requires very low amounts of sample, due to the intrinsic sensitivity of mass spectrometry. This may prove particularly useful when the amount of sample available prevents the use of current methods.

  6. On the divergences in assessment of environmental impacts from ionising radiation following the Fukushima accident.

    PubMed

    Strand, P; Sundell-Bergman, S; Brown, J E; Dowdall, M

    2017-04-01

    The accident at the Fukushima-Daiichi Nuclear Power Station on March 11, 2011, led to significant contamination of the surrounding terrestrial and marine environments. Whilst impacts on human health remain the primary concern in the aftermath of such an accident, recent years have seen a significant body of work conducted on the assessment of the accident's impacts on both the terrestrial and marine environment. Such assessments have been undertaken at various levels of biological organisation, for different species, using different methodologies and coming, in many cases, to divergent conclusions as to the effects of the accident on the environment. This article provides an overview of the work conducted in relation to the environmental impacts of the Fukushima accident, critically comparing and contrasting methodologies and results with a view towards finding reasons for discrepancies, should they indeed exist. Based on the outcomes of studies conducted to date, it would appear that in order to avoid the fractured and disparate conclusions drawn in the aftermath of previous accidents, radioactive contaminants and their effects can no longer simply be viewed in isolation with respect to the ecosystems these effects may impact. A combination of laboratory based and field studies with a focus on ecosystem functioning and effects could offer the best opportunities for coherence in the interpretation of the results of studies into the environmental impacts of ionising radiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Recombination in liquid filled ionisation chambers with multiple charge carrier species: Theoretical and numerical results

    NASA Astrophysics Data System (ADS)

    Aguiar, P.; González-Castaño, D. M.; Gómez, F.; Pardo-Montero, J.

    2014-10-01

    Liquid-filled ionisation chambers (LICs) are used in radiotherapy for dosimetry and quality assurance. Volume recombination can be quite important in LICs for moderate dose rates, causing non-linearities in the dose rate response of these detectors, and needs to be corrected for. This effect is usually described with Greening and Boag models for continuous and pulsed radiation respectively. Such models assume that the charge is carried by two different species, positive and negative ions, each of those species with a given mobility. However, LICs operating in non-ultrapure mode can contain different types of electronegative impurities with different mobilities, thus increasing the number of different charge carriers. If this is the case, Greening and Boag models can be no longer valid and need to be reformulated. In this work we present a theoretical and numerical study of volume recombination in parallel-plate LICs with multiple charge carrier species, extending Boag and Greening models. Results from a recent publication that reported three different mobilities in an isooctane-filled LIC have been used to study the effect of extra carrier species on recombination. We have found that in pulsed beams the inclusion of extra mobilities does not affect volume recombination much, a behaviour that was expected because Boag formula for charge collection efficiency does not depend on the mobilities of the charge carriers if the Debye relationship between mobilities and recombination constant holds. This is not the case in continuous radiation, where the presence of extra charge carrier species significantly affects the amount of volume recombination.

  8. Ionised concentrations in calcium and magnesium buffers: Standards and precise measurement are mandatory.

    PubMed

    McGuigan, John A S; Kay, James W; Elder, Hugh Y

    2016-09-01

    In Ca(2+) and Mg(2+) buffer solutions the ionised concentrations ([X(2+)]) are either calculated or measured. Calculated values vary by up to a factor of seven due to the following four problems: 1) There is no agreement amongst the tabulated constants in the literature. These constants have usually to be corrected for ionic strength and temperature. 2) The ionic strength correction entails the calculation of the single ion activity coefficient, which involves non-thermodynamic assumptions; the data for temperature correction is not always available. 3) Measured pH is in terms of activity i.e. pHa. pHa measurements are complicated by the change in the liquid junction potentials at the reference electrode making an accurate conversion from H(+) activity to H(+) concentration uncertain. 4) Ligands such as EGTA bind water and are not 100% pure. Ligand purity has to be measured, even when the [X(2+)] are calculated. The calculated [X(2+)] in buffers are so inconsistent that calculation is not an option. Until standards are available, the [X(2+)] in the buffers must be measured. The Ligand Optimisation Method is an accurate and independently verified method of doing this (McGuigan & Stumpff, Anal. Biochem. 436, 29, 2013). Lack of standards means it is not possible to compare the published [Ca(2+)] in the nmolar range, and the apparent constant (K(/)) values for Ca(2+) and Mg(2+) binding to intracellular ligands amongst different laboratories. Standardisation of Ca(2+)/Mg(2+) buffers is now essential. The parameters to achieve this are proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Accurate simulation of ionisation chamber response with the Monte Carlo code PENELOPE

    NASA Astrophysics Data System (ADS)

    Sempau, Josep; Andreo, Pedro

    2011-08-01

    Ionisation chambers (IC) are routinely used in hospitals for the dosimetry of the photon and electron beams used for radiotherapy treatments. The determination of absorbed dose to water from the absorbed dose to the air filling the cavity requires the introduction of stopping power ratios and perturbation factors, which account for the disturbance caused by the presence of the chamber. Although this may seem a problem readily amenable to Monte Carlo simulation, the fact is that the accurate determination of IC response has been, for various decades, one of the most important challenges of the simulation of electromagnetic showers. The main difficulty stems from the use of condensed history techniques for electron and positron transport. This approach, which involves grouping a large number of interactions into a single artificial event, is known to produce the so-called interface effects when particles travel across surfaces separating different media. These effects can be sizeable when the electron step length is not negligible compared to the size of the region being crossed, as it is the case with the cavity of an IC. The artefact, which becomes apparent when the chamber response shows a marked dependence on the adopted step size, can be palliated with the use of sophisticated electron transport algorithms. These topics are discussed in the context of the transport model implemented in the PENELOPE code. The degree of violation of the Fano theorem for a simple, planar geometry, is used as a measure of the stability of the algorithm with respect to variations of the electron step length, thus assessing the "quality" of its condensed history scheme. It is shown that, with a suitable choice of transport parameters, PENELOPE simulates IC response with an accuracy of the order of 0.1%.

  10. The Vertical Structure of Warm Ionised Gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Gaensler, B. M.; Madsen, G. J.; Chatterjee, S.; Mao, S. A.

    2008-11-01

    We present a new joint analysis of pulsar dispersion measures and diffuse Hα emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by Hii regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830-250+120 pc, a factor of two larger than has been derived in previous studies. The corresponding inconsistent scale heights for dispersion measure and emission measure imply that the vertical profiles of mass and pressure in the WIM are decoupled, and that the filling factor of WIM clouds is a geometric response to the competing environmental influences of thermal and non-thermal processes. Extrapolating the properties of the thick-disk WIM to mid-plane, we infer a volume-averaged electron density 0.014 +/- 0.001 cm-3, produced by clouds of typical electron density 0.34 +/- 0.06 cm-3 with a volume filling factor 0.04 +/- 0.01. As one moves off the plane, the filling factor increases to a maximum of ~30% at a height of ~1-1.5 kpc, before then declining to accommodate the increasing presence of hot, coronal gas. Since models for the WIM with a ~1 kpc scale-height have been widely used to estimate distances to radio pulsars, our revised parameters suggest that the distances to many high-latitude pulsars have been substantially underestimated.

  11. Screening for medium chain acyl-CoA dehydrogenase deficiency using electrospray ionisation tandem mass spectrometry

    PubMed Central

    Clayton, P.; Doig, M.; Ghafari, S.; Meaney, C.; Taylor, C.; Leonard, J.; Morris, M.; Johnson, A.

    1998-01-01

    OBJECTIVE—To establish criteria for the diagnosis of medium chain acyl-CoA dehydrogenase (MCAD) deficiency in the UK population using a method in which carnitine species eluted from blood spots are butylated and analysed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS).
DESIGN—Four groups were studied: (1) 35 children, aged 4 days to 16.2 years, with proven MCAD deficiency (mostly homozygous for the A985G mutation, none receiving carnitine supplements); (2) 2168control children; (3) 482 neonates; and (4) 15 MCAD heterozygotes.
RESULTS—All patients with MCAD deficiency had an octanoylcarnitine concentration ([C8-Cn]) > 0.38 µM and no accumulation of carnitine species > C10 or < C6. Among the patients with MCAD deficiency, the [C8-Cn] was significantly lower in children > 10 weeks old and in children with carnitine depletion (free carnitine < 20 µM). Neonatal blood spots from patients with MCAD deficiency had a [C8-Cn] > 1.5 µM, whereas in heterozygotes and other normal neonates the [C8-Cn] was < 1.0 µM. In contrast, the blood spot [C8-Cn] in eight of 27 patients with MCAD deficiency > 10 weeks old fell within the same range as five of 15 MCAD heterozygotes (0.38-1.0 µM). However, the free carnitine concentrations were reduced (< 20 µM) in the patients with MCAD deficiency but normal in the heterozygotes.
CONCLUSIONS—Criteria for the diagnosis of MCAD deficiency using ESI-MS/MS must take account of age and carnitine depletion. If screening is undertaken at 7-10 days, the number of false positive and negative results should be negligible. Because there have been no instances of death or neurological damage following diagnosis of MCAD deficiency in our patient group, a strong case can be made for neonatal screening for MCAD deficiency in the UK.

 PMID:9797589

  12. Resveratrol and its methoxy-derivatives as modulators of DNA damage induced by ionising radiation.

    PubMed

    Traversi, Gianandrea; Fiore, Mario; Leone, Stefano; Basso, Emiliano; Di Muzio, Elena; Polticelli, Fabio; Degrassi, Francesca; Cozzi, Renata

    2016-07-01

    Various naturally occurring stilbene-like compounds that are related to resveratrol (RSV) possess some of the beneficial effects of the parent molecule and provide even further benefits. Therefore, a series of methoxylated analogues of RSV were prepared with the aim of increasing antitumour and proapoptotic activity. In a previous article, we studied two methoxy-derivatives, pterostilbene (PTERO) and trimethoxystilbene (TRIMETHOXY), in which the first was formed by the substitution of two hydroxyl groups with two methoxy groups (trans-3,5-dimethoxy-4'-hydroxystilbene) and the second was formed by the replacement of all three OH groups with methoxy groups (trans-3,5,4'-trimethoxystilbene). Both methoxy-derivatives showed stronger antioxidant activity when compared with RSV. In the present article, we focused on the analysis of the ability of RSV and its two methoxylated derivatives to protect proliferating non-tumoural cells from the damage induced by ionising radiation (IR). First we showed that the methoxy derivatives, contrary to their parental compound, are unable to affect topoisomerase enzyme and consequently are not clastogenic per se Second we showed that both PTERO and TRIMETHOXY more efficiently reduce the chromosome damage induced by IR. Furthermore, TRIMETHOXY, but not PTERO, causes a delay in cell proliferation, particularly in mitosis progression increasing the number of cells in metaphase at the expense of prophases and ana/telophases. © The Author 2016. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Contribution to the Interpretation of Emission-line spectra in Ionised Nebulae

    NASA Astrophysics Data System (ADS)

    Rola, C. S.

    1995-05-01

    The study of ionised nebulae from their emission-line intensities is the aim of this work. It concerns two complementary aspects. Firstly, we have studied the influence of the emission-line detection and measurement procedures in the values of the measured intensities. Secondly, we have developed diagnostic methods for the determination of the nature and physical properties of emission-line objects, using a minimum number of line intensities. Detailed simulations of the emission-line detection and intensity measurement procedures allowed us to estimate the errors committed in the intensity measurement of lines with low signal-to-noise ratio. Obtained results permitted us to show the existence of a bias in the measured intensities distribution and to determine a model for it. Furthermore, we determined analytically the probability distribution function of a intensity lines ratio. In this context, we have studied the effect of uncertainties in the intensity measures, and of temperature fluctuations in the determination of the C/O abundance ratio in planetary nebulae. With the purpose of determining the characteristics and the nature of emission-line objects having only a few line intensities available, we calculated the upper limits for photoionisation by OB stars in diagnostic diagrams. For this we build an extensive grid of photoionisation models covering a wide range of physical conditions in H II regions. The results obtained were used in the determination of the nature of the "Canada-France Redshift Survey" emission-line field galaxies, showing the importance of this type of diagnostic in deep redshift surveys.

  14. Low-dose ionising radiation and cardiovascular diseases--Strategies for molecular epidemiological studies in Europe.

    PubMed

    Kreuzer, Michaela; Auvinen, Anssi; Cardis, Elisabeth; Hall, Janet; Jourdain, Jean-Rene; Laurier, Dominique; Little, Mark P; Peters, Annette; Raj, Ken; Russell, Nicola S; Tapio, Soile; Zhang, Wei; Gomolka, Maria

    2015-01-01

    It is well established that high-dose ionising radiation causes cardiovascular diseases. In contrast, the evidence for a causal relationship between long-term risk of cardiovascular diseases after moderate doses (0.5-5 Gy) is suggestive and weak after low doses (<0.5 Gy). However, evidence is emerging that doses under 0.5 Gy may also increase long-term risk of cardiovascular disease. This would have major implications for radiation protection with respect to medical use of radiation for diagnostic purposes and occupational or environmental radiation exposure. Therefore, it is of great importance to gain information about the presence and possible magnitude of radiation-related cardiovascular disease risk at doses of less than 0.5 Gy. The biological mechanisms implicated in any such effects are unclear and results from epidemiological studies are inconsistent. Molecular epidemiological studies can improve the understanding of the pathogenesis and the risk estimation of radiation-induced circulatory disease at low doses. Within the European DoReMi (Low Dose Research towards Multidisciplinary Integration) project, strategies to conduct molecular epidemiological studies in this field have been developed and evaluated. Key potentially useful European cohorts are the Mayak workers, other nuclear workers, uranium miners, Chernobyl liquidators, the Techa river residents and several diagnostic or low-dose radiotherapy patient cohorts. Criteria for informative studies are given and biomarkers to be investigated suggested. A close collaboration between epidemiology, biology and dosimetry is recommended, not only among experts in the radiation field, but also those in cardiovascular diseases.

  15. Cancer

    MedlinePlus

    ... Healthcare ManagementFamily HealthProcedures & DevicesHealthcare ManagementRelated TopicsCancer: Medical VocabularyRead Article >>Cancer: Medical Vocabulary Learn the definitions of various terms ...

  16. Cancer

    MedlinePlus

    Cancer begins in your cells, which are the building blocks of your body. Normally, your body forms ... be benign or malignant. Benign tumors aren't cancer while malignant ones are. Cells from malignant tumors ...

  17. Nurses', physicians' and radiographers' perceptions of the safety of a nurse prescribing of ionising radiation initiative: A cross-sectional survey.

    PubMed

    Hyde, Abbey; Coughlan, Barbara; Naughton, Corina; Hegarty, Josephine; Savage, Eileen; Grehan, Jennifer; Kavanagh, Eoin; Moughty, Adrian; Drennan, Jonathan

    2016-06-01

    A new initiative was introduced in Ireland following legislative changes that allowed nurses with special training to prescribe ionising radiation (X-ray) for the first time. A small number of studies on nurse prescribing of ionising radiation in other contexts have found it to be broadly as safe as ionising radiation prescribing by physicians. Sociological literature on perceptions of safety indicates that these tend to be shaped by the ideological position of the professional rather than based on objective evidence. To describe, compare and analyse perceptions of the safety of a nurse prescribing of ionising radiation initiative across three occupational groups: nursing, radiography and medicine. A cross-sectional survey design. Participants were drawn from a range of clinical settings in Ireland. Respondents were 167 health professionals comprised of 49 nurses, 91 radiographers, and 27 physicians out of a total of 300 who were invited to participate. Non-probability sampling was employed and the survey was targeted specifically at health professionals with a specific interest in, or involvement with, the development of the nurse prescribing of ionising radiation initiative in Ireland. Comparisons of perspectives on the safety of nurse prescribing of ionising radiation across the three occupational groups captured by questionnaire were analysed using the Kruskal-Wallis H test. Pairwise post hoc tests were conducted using the Mann-Whitney U test. While the majority of respondents from all three groups perceived nurse prescribing of ionising radiation to be safe, the extent to which this view was held varied. A higher proportion of nurses was found to display confidence in the safety of nurse prescribing of ionising radiation compared to physicians and radiographers with differences between nurses' perceptions and those of the other two groups being statistically significant. That an occupational patterning emerged suggests that perceptions about safety and risk of

  18. Measurement of air kerma rates for 6- to 7-MeV high-energy gamma-ray field by ionisation chamber and build-up plate.

    PubMed

    Kowatari, Munehiko; Tanimura, Yoshihiko; Tsutsumi, Masahiro

    2014-12-01

    The 6- to 7-MeV high-energy gamma-ray calibration field by the (19)F(p, αγ)(16)O reaction is to be served at the Japan Atomic Energy Agency. For the determination of air kerma rates using an ionisation chamber in the 6- to 7-MeV high-energy gamma-ray field, the establishment of the charged particle equilibrium must be achieved during measurement. In addition to measurement of air kerma rates by the ionisation chamber with a thick build-up cap, measurement using the ionisation chamber and a build-up plate (BUP) was attempted, in order to directly determine air kerma rates under the condition of regular calibration for ordinary survey meters and personal dosemeters. Before measurements, Monte Carlo calculations were made to find the optimum arrangement of BUP in front of the ionisation chamber so that the charged particle equilibrium could be well established. Measured results imply that air kerma rates for the 6- to 7-MeV high-energy gamma-ray field could be directly determined under the appropriate condition using an ionisation chamber coupled with build-up materials. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Event-based versus process-based informed consent to address scientific evidence and uncertainties in ionising medical imaging.

    PubMed

    Recchia, Virginia; Dodaro, Antonio; Braga, Larissa

    2013-10-01

    Inappropriate ionising medical imaging has been escalating in the last decades. This trend leads to potential damage to health and has been associated to bioethical and legal issues of patient autonomy. While the doctrine underlines the importance of using informed consent to improve patient autonomy and physician-patient communication, some researchers have argued that it often falls short of this aim. There are basically two different informed consent practices. The first - the so-called "event-based model" - regards informed consent as a passive signature of a standard unreadable template, performed only once in each medical pathway. The second - the so-called "process-based model" - integrates information into the continuing dialogue between physician and patient, vital for diagnosis and treatment. Current medical behaviour often embraces the event-based model, which is considered ineffective and contributes to inappropriateness. We sought, in this review, to analyse from juridical and communication standpoints whether process-based informed consent can deal with scientific uncertainties in radiological decision-making. The informed consent is still a distinctive process in defence of both patients' and physicians' health and dignity in rule-of-law states and consequently in curtailing the abuse of ionising medical radiation. • Inappropriate ionising medical imaging is widespread and increasing worldwide. • This trend leads to noteworthy damage to health and is linked to the issue of patient autonomy. • Some authors have argued that informed consent often falls short of improving patient autonomy. • Process-based informed consent can deal with scientific uncertainties to contrast inappropriateness. • Informed consent is still a distinctive process in defence of both patients and physicians.

  20. Predicting the effects of ionising radiation on ecosystems by a generic model based on the Lotka-Volterra equations.

    PubMed

    Monte, Luigi

    2009-06-01

    The present work describes a model for predicting the population dynamics of the main components (resources and consumers) of terrestrial ecosystems exposed to ionising radiation. The ecosystem is modelled by the Lotka-Volterra equations with consumer competition. Linear dose-response relationships without threshold are assumed to relate the values of the model parameters to the dose rates. The model accounts for the migration of consumers from areas characterised by different levels of radionuclide contamination. The criteria to select the model parameter values are motivated by accounting for the results of the empirical studies of past decades. Examples of predictions for long-term chronic exposure are reported and discussed.

  1. The inverse-square gamma-irradiation anomaly of the Nuclear Enterprises 2575 large-volume ionisation chamber.

    PubMed

    Bielajew, Alex F; Tessier, Frédéric; El Gamal, Islam

    2015-12-01

    The Nuclear Enterprises (Model 2575) 600 cc ionisation chamber is examined to discover the cause of its anomalous behaviour in inverse-square stability measurements. Measurements and Monte Carlo calculations are employed to isolate the cause of the discrepancy. It is found that most of the effect is due to the long photon attenuation pathlengths in the long side wall of the instrument. A phenomenological procedure, based on measurements, is proposed to correct for the anomaly. The procedure results in inverse-square stability to within 0.5 % over a range of 1-7 m.

  2. Interpretation of ionospheric F-region structures in the vicinity of ionisation troughs observed by satellite radio tomography

    NASA Astrophysics Data System (ADS)

    Aladjev, G. A.; Evstafiev, O. V.; Mingalev, V. S.; Mingaleva, G. I.; Tereshchenko, E. D.; Khudukon, B. Z.

    2001-01-01

    Tomographic images of the spatial distribution of electron density in the ionospheric F-region are presented from the Russian-American Tomography Experiment (RATE) in November 1993 as well as from campaigns carried out in northern Scandinavia in November 1995 and in Russia in April 1990. The reconstructions selected display the ionisation troughs above the tomographic chains of receivers during geomagnetically quiet and disturbed periods. Two mathematical models of the high-latitude ionosphere developed in the Polar Geophysical Institute have been applied for interpretation of the observed tomographic images.

  3. Capillary electrophoresis with electrospray ionisation-mass spectrometry for the characterisation of degradation products in aged papers.

    PubMed

    Dupont, Anne-Laurence; Seemann, Agathe; Lavédrine, Bertrand

    2012-01-30

    A methodology for capillary electrophoresis/electrospray ionisation mass spectrometry (CE/ESI-MS) was developed for the simultaneous analysis of degradation products from paper among two families of compounds: low molar mass aliphatic organic acids, and aromatic (phenolic and furanic) compounds. The work comprises the optimisation of the CE separation and the ESI-MS parameters for improved sensitivity with model compounds using two successive designs of experiments. The method was applied to the analysis of lignocellulosic paper at different stages of accelerated hygrothermal ageing. The compounds of interest were identified. Most of them could be quantified and several additional analytes were separated.

  4. Current status of matrix-assisted laser desorption ionisation-time of flight mass spectrometry in the clinical microbiology laboratory.

    PubMed

    Kok, Jen; Chen, Sharon C A; Dwyer, Dominic E; Iredell, Jonathan R

    2013-01-01

    The integration of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) into many clinical microbiology laboratories has revolutionised routine pathogen identification. MALDI-TOF MS complements and has good potential to replace existing phenotypic identification methods. Results are available in a more clinically relevant timeframe, particularly in bacteraemic septic shock. Novel applications include strain typing and the detection of antimicrobial resistance, but these are not widely used. This review discusses the technical aspects, current applications, and limitations of MALDI-TOF MS.

  5. Development of a rest gas ionisation profile monitor for the CERN Proton Synchrotron based on a Timepix3 pixel detector

    NASA Astrophysics Data System (ADS)

    Levasseur, S.; Dehning, B.; Gibson, S.; Sandberg, H.; Sapinski, M.; Sato, K.; Schneider, G.; Storey, J.

    2017-02-01

    A fast non-destructive transverse profile monitor, named PS Beam Gas Ionization monitor (PS- BGI), is under development at CERN for the Proton Synchrotron (PS). This monitor infers the beam profile from the transverse distribution of electrons created by the ionisation of rest gas molecules by the high energy beam particles. The distribution is measured by accelerating the electrons onto an imaging detector based on Timepix3 (TPX3). This detector consists of hybrid pixel detector assemblies mounted on a ceramic carrier board and flexible printed circuit cables which have been developed specifically for operation in an ultra high vacuum environment.

  6. The solar ionisation rate deduced from Ulysses measurements and its implications to interplanetary Lyman alpha-intensity

    NASA Technical Reports Server (NTRS)

    Summanen, T.; Kyroelae, E.

    1995-01-01

    We have developed a computer code which can be used to study 3-dimensional and time-dependent effects of the solar cycle on the interplanetary (IP) hydrogen distribution. The code is based on the inverted Monte Carlo simulation. In this work we have modelled the temporal behaviour of the solar ionisation rate. We have assumed that during the most of the time of the solar cycle there is an anisotopic latitudinal structure but right at the solar maximum the anisotropy disappears. The effects of this behaviour will be discussed both in regard to the IP hydrogen distribution and IP Lyman a a-intensity.

  7. Evaluation of a pulse-discharge helium ionisation detector for the determination of neon concentrations by gas chromatography.

    PubMed

    Lasa, J; Mochalski, P; Pusz, J

    2004-05-07

    A pulse-discharge helium ionisation detector, PDHID (Valco, PD-D2-I) with sample introduced to the discharge zone is shown to be applicable for reliable determinations of neon by gas chromatography. The detection level of 80 pg was obtained, but the dependence between detector response and neon mass was non-linear. However, for the discharge gas doped with 33 ppm of neon, a linear response to the neon mass up to 10(-5) g and the detection level of 0.5 ng were obtained. The method can be used for measuring neon concentrations in groundwater systems for hydrogeological purposes.

  8. Static electric fields interfere in the viability of cells exposed to ionising radiation.

    PubMed

    Arruda-Neto, João D T; Friedberg, Errol C; Bittencourt-Oliveira, Maria C; Cavalcante-Silva, Erika; Schenberg, Ana C G; Rodrigues, Tulio E; Garcia, Fermin; Louvison, Monica; Paula, Claudete R; Mesa, Joel; Moron, Michelle M; Maria, Durvanei A; Genofre, Godofredo C

    2009-04-01

    The interference of electric fields (EF) with biological processes is an issue of considerable interest. No studies have as yet been reported on the combined effect of EF plus ionising radiation. Here we report studies on this combined effect using the prokaryote Microcystis panniformis, the eukaryote Candida albicans and human cells. Cultures of Microcystis panniformis (Cyanobacteria) in glass tubes were irradiated with doses in the interval 0.5-5 kGy, using a (60)Co gamma source facility. Samples irradiated with 3 kGy were exposed for 2 h to a 20 V . cm(-1) static electric field and viable cells were enumerated. Cultures of Candida albicans were incubated at 36 degrees C for 20 h, gamma-irradiated with doses from 1-4 kGy, and submitted to an electric field of 180 V . cm(-1). Samples were examined under a fluorescence microscope and the number of unviable (red) and viable (apple green fluorescence) cells was determined. For crossing-check purposes, MRC5 strain of lung cells were irradiated with 2 Gy, exposed to an electric field of 1250 V/cm, incubated overnight with the anti-body anti-phospho-histone H2AX and examined under a fluorescence microscope to quantify nuclei with gamma-H2AX foci. In cells exposed to EF, death increased substantially compared to irradiation alone. In C. albicans we observed suppression of the DNA repair shoulder. The effect of EF in growth of M. panniformis was substantial; the number of surviving cells on day-2 after irradiation was 12 times greater than when an EF was applied. By the action of a static electric field on the irradiated MRC5 cells the number of nuclei with gamma-H2AX foci increased 40%, approximately. Application of an EF following irradiation greatly increases cell death. The observation that the DNA repair shoulder in the survival curve of C. albicans is suppressed when cells are exposed to irradiation + EF suggests that EF likely inactivate cellular recovering processes. The result for the number of nuclei with gamma

  9. New laboratory atomic data for neutral, singly and doubly ionised iron group elements for astrophysics applications

    NASA Astrophysics Data System (ADS)

    Pickering, Juliet C.; Nave, Gillian; Liggins, Florence; Clear, Christian; Ruffoni, Matthew; Sansonetti, Craig

    2015-08-01

    We present new laboratory spectroscopic measurements to produce atomic data for astrophysically important species: neutral, singly and doubly ionised iron group elements.We use high resolution Fourier Transform Spectrometry (FTS) (resolving power up to 2x106 at 200nm) to measure atomic spectra, giving accurate line wavelengths (to a few parts in 108), atomic energy levels, hyperfine structure splitting and log gfs (accurate to a few %) (Ruffoni et al this meeting). These data are vital for astrophysical spectral analyses for: line identification, spectrum synthesis, elemental abundance determinations [eg 1], and disentangling of blends etc. It is not possible to theoretically calculate these atomic data to the accuracy needed for modern astrophysics applications.At Imperial College we have a unique visible-VUV FT spectrometer with short wavelength cut-off of 135nm. We supplement FTS data at shorter wavelengths with spectra recorded on the NIST 10.7m grating spectrograph (with phosphor image or photographic plates) and at longer wavelengths in the IR we use the NIST IR FT spectrometer.An elemental spectrum may contain thousands of spectral lines from the IR to VUV. We use these wavelengths to correct known atomic energy levels, and search for new atomic levels. The result is a classified linelist and accurate atomic energy levels.We present progress on iron group element atomic energy levels and wavelengths for V I and V II [2,3], Co III [4], Cr I, Mn I and Mn II, and Ni II.This work is supported by STFC(UK), The Leverhulme Trust, The Royal Society and NASA.References[1] Bergemann M, Pickering JC & Gehren T,“NLTE analysis of Co I/Co II lines in spectra of cool stars with new laboratory hyperfine splitting constants",MNRAS 401(2) 1334 (2010)[2] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V II”, ApJS 207,13 (2013)[3] Thorne AP, Pickering JC & Semeniuk J,“The spectrum and term analysis of V I",ApJS 192,11 (2011)[4] Smillie DG

  10. WE-G-BRA-06: Calibrating an Ionisation Chamber: Gaining Experience Using a Dosimetry 'flight Simulator'.

    PubMed

    Beavis, A; Saunderson, J; Ward, J

    2012-06-01

    Recently there has been great interest in the use of simulation training, with the view to enhance safety within radiotherapy practice. We have developed a Virtual Environment for Radiotherapy Training (VERT) which facilitates this, including the simulation of a number of 'Physics practices'. One such process is the calibration of an ionisation chamber for use in Linac photon beams. The VERT system was used to provide a life sized 3D virtual environment within which we were able to simulate the calibration of a departmental chamber for 6MV and 15 MV beams following the UK 1990 Code of Practice. The characteristics of the beams are fixed parameters in the simulation, whereas default (Absorbed dose to water) correction factors of the chambers are configurable thereby dictating their response in the virtual x-ray beam. When the simulation is started, a random, realistic temperature and pressure is assigned to the bunker. Measurement and chamber positional errors are assigned to the chambers. A virtual water phantom was placed on the Linac couch and irradiated through the side using a 10 × 10 field. With a chamber at the appropriate depths and irradiated iso-centrically, the Quality Indices (QI) of the beams were obtained. The two chambers were 'inter-compared', allowing the departmental chamber calibration factor to be calculated from that of the reference chamber. For the virtual 6/15 MV beams, the QI were found to be 0.668/ 0.761 and the inter-comparison ratios 0.4408/ 0.4402 respectively. The departmental chamber calibration factors were calculated; applying these and appropriate environmental corrections allowed the output of the Linac to be confirmed. We have shown how a virtual training environment can be used to demonstrate practical processes and reinforce learning. The UK CoP was used here, however any relevant protocol could be demonstrated. Two of the authors (Beavis and Ward) are Founders of Vertual Ltd, a spin-out company created to commercialise the

  11. Determination of chlorinated paraffins in sediments from the Firth of Clyde by gas chromatography with electron capture negative ionisation mass spectrometry and carbon skeleton analysis by gas chromatography with flame ionisation detection.

    PubMed

    Hussy, Ines; Webster, Lynda; Russell, Marie; Moffat, Colin

    2012-07-01

    Short chain chlorinated paraffins (SCCPs) are a group of persistent organic pollutants (POPs) of increasing concern, but are to date not widely investigated in the environment, largely due to the challenges involved in their quantification. Here, SCCPs were quantified in marine sediments from the Firth of Clyde, Scotland, by gas chromatography with electron capture negative ionisation mass spectrometry (GC-ECNIMS) and through carbon skeleton analysis by gas chromatography with flame ionisation detection (GC-FID), and the analytical challenges encountered are discussed. Concentrations in the sediments ranged from 0.4 to 69 μg kg(-1) when determined by GC-ECNIMS, and from 5.6 to 379 μg kg(-1) when determined by GC-FID. For 8 out of 11 samples, analysis by GC-FID gave higher results than analysis by GC-ECNIMS. Unexpected aspects of the analysis, such as the presence of high concentrations of longer chain chlorinated paraffins in the samples, are also presented.

  12. [Cancer].

    PubMed

    de la Peña-López, Roberto; Remolina-Bonilla, Yuly Andrea

    2016-09-01

    Cancer is a group of diseases which represents a significant public health problem in Mexico and worldwide. In Mexico neoplasms are the second leading cause of death. An increased morbidity and mortality are expected in the next decades. Several preventable risk factors for cancer development have been identified, the most relevant including tobacco use, which accounts for 30% of the cancer cases; and obesity, associated to another 30%. These factors, in turn, are related to sedentarism, alcohol abuse and imbalanced diets. Some agents are well knokn to cause cancer such as ionizing radiation, viruses such as the papilloma virus (HPV) and hepatitis virus (B and C), and more recently environmental pollution exposure and red meat consumption have been pointed out as carcinogens by the International Agency for Research in Cancer (IARC). The scientific evidence currently available is insufficient to consider milk either as a risk factor or protective factor against different types of cancer.

  13. Laboratory studies of peroxy radical reactions using the turbulent flow chemical ionisation mass spectrometer technique

    NASA Astrophysics Data System (ADS)

    Bacak, A.; Bardwell, M.; Percival, C.

    2003-04-01

    HO_x (sum of OH and HO_2) plays an important role in the formation of tropospheric O_3 recently Wennberg et al.,^1 pointed out that the formation of tropospheric O_3 is strongly dependent on the level of NO_x as a consequence of its reaction with RO_2 (where R=H or CH_3). It is therefore important to characterise the coupling of NO_x and RO_2 to understand the tropospheric O_3 budget. Model studies have shown in the mid to upper troposphere both HO_2NO_2 and CH_3O_2NO_2 may well constitute a significant fraction of NO_y (˜20%). Despite the importance of these species, there are little or no experimental data available on their formation in this region. At present models do not accurately describe the observed nitrogen partitioning, in particular underpredicting the ratio NO_x/NO_y Recently Brown et al.,^2 have measured key rate coefficients over a wider range of pressure and temperature than performed previously and have shown that the formation of NO_y is much slower than previously estimated from extrapolation of available kinetic data to low temperatures Gao et al.,^3 have observed that these new kinetic data improve the agreement between model and measurements in the lower stratosphere and troposphere respectively, but that discrepancies still exist which must be addressed. The temperatures (180-300 K) encountered in the troposphere pose a significant challenge to laboratory studies. Although much progress has been made in this respect over the years, there still remains considerable uncertainties in the kinetic data base, particularly for conditions of lowest temperature (180 - 250 K) and pressures (70 Torr) that pertain to the UTLS region. A turbulent flow CIMS (as shown in figure 1) has been developed to study the reaction of RO_2 with NO over the pressure range 70-760 Torr and temperatures as low as 170 K. The CIMS is used to detect all trace species in the flow tube. Chemical ionisation takes place through the following reaction scheme. X^- + RO_2

  14. Hybrid modelling of cometary plasma environments. I. Impact of photoionisation, charge exchange, and electron ionisation on bow shock and cometopause at 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, C.; Alho, M.; Gronoff, G.; Kallio, E.; Gunell, H.; Nilsson, H.; Lindkvist, J.; Behar, E.; Stenberg Wieser, G.; Miloch, W. J.

    2017-08-01

    Context. The ESA/Rosetta mission made it possible to monitor the plasma environment of a comet, from near aphelion to perihelion conditions. To understand the complex dynamics and plasma structures found at the comet, a modelling effort must be carried out in parallel. Aims: Firstly, we present a 3D hybrid model of the cometary plasma environment including photoionisation, solar wind charge exchange, and electron ionisation reactions; this model is used in stationary and dynamic conditions (mimicking the solar wind variations), and is thus especially adapted to a weakly outgassing comet such as 67P/Churyumov-Gerasimenko, the target of the ESA/Rosetta mission. Secondly, we use the model to study the respective effects of ionisation processes on the formation of the dayside macroscopic magnetic and density boundaries upstream of comet 67P in perihelion conditions at 1.3 AU. Thirdly, we explore and discuss the effects of these processes on the magnetic field line draping, ionisation rates, and composition in the context of the Rosetta mission. Methods: We used a new quasi-neutral hybrid model, originally designed for weakly magnetised planetary bodies, such as Venus, Mars, and Titan, and adapted here to comets. Ionisation processes were monitored individually and together following a probabilistic interaction scheme. Three-dimensional paraboloid fits of the bow shock surface, identified for a magnetosonic Mach number equal to 2, and of the cometopause surface, were performed for a more quantitative analysis. Results: We show that charge exchange and electron ionisation play a major role in the formation of a bow shock-like structure far upstream, while photoionisation is the main driver at and below the cometopause boundary, within 1000 km cometocentric distance. Charge exchange contributes to 42% of the total production rate in the simulation box, whereas production rates from electron ionisation and photoionisation reach 33% and 25%, respectively. We also discuss

  15. Zwitterionic clusters with dianion core produced by electrospray ionisation of Brønsted acidic ionic liquids.

    PubMed

    Li, Jing; Wei, Wei; Nye, Leanne C; Schulz, Peter S; Wasserscheid, Peter; Ivanović-Burmazović, Ivana; Drewello, Thomas

    2012-04-21

    New Brønsted acidic ionic liquids (BAILs) are prepared by treating zwitterions, which are composed of an imidazolium cation and a sulfonate anion, with an alkanedisulfonic acid. Acidification of the zwitterions produces the cation and deprotonation of the alkanedisulfonic acid forms the anion of the new BAILs. Direct laser desorption/ionisation (LDI), matrix-assisted LDI (MALDI) and electrospray ionisation (ESI) are employed to transfer ions into the gas-phase for detection by mass spectrometry and for dissociation studies by tandem mass spectrometry. The components of the BAILs are confirmed by LDI and MALDI by the detection of the respective cation and anion and by ESI by the observation of the cation and the dianion. A prominent feature of ESI is the formation of aggregates (cluster ions). Positively charged cluster ions are formally composed of multiple zwitterions plus one additional proton. In the negative-ion mode the clusters also incorporate the zwitterions which are, however, linked with the alkanedisulfonate dianion. In collision-induced dissociations (CID), the cationic aggregates show the evaporation of zwitterions until the protonated zwitterion is reached. Similarly, the cluster dianions release zwitterions until the free alkane disulfonate dianion is reached. However, the 1:1 adduct of dianion and zwitterion also displays proton transfer and Coulomb explosion into the mono-protonated disulfonic mono-anion and an imidazole-based carbene with sulfonate mono-anion. This journal is © the Owner Societies 2012

  16. Leaf Anatomy and Photochemical Behaviour of Solanum lycopersicum L. Plants from Seeds Irradiated with Low-LET Ionising Radiation

    PubMed Central

    De Micco, V.; Paradiso, R.; Aronne, G.; De Pascale, S.; Quarto, M.; Arena, C.

    2014-01-01

    Plants can be exposed to ionising radiation not only in Space but also on Earth, due to specific technological applications or after nuclear disasters. The response of plants to ionising radiation depends on radiation quality/quantity and/or plant characteristics. In this paper, we analyse some growth traits, leaf anatomy, and ecophysiological features of plants of Solanum lycopersicum L. “Microtom” grown from seeds irradiated with increasing doses of X-rays (0.3, 10, 20, 50, and 100 Gy). Both juvenile and compound leaves from plants developed from irradiated and control seeds were analysed through light and epifluorescence microscopy. Digital image analysis allowed quantifying anatomical parameters to detect the occurrence of signs of structural damage. Fluorescence parameters and total photosynthetic pigment content were analysed to evaluate the functioning of the photosynthetic machinery. Radiation did not affect percentage and rate of seed germination. Plants from irradiated seeds accomplished the crop cycle and showed a more compact habitus. Dose-depended tendencies of variations occurred in phenolic content, while other leaf anatomical parameters did not show distinct trends after irradiation. The sporadic perturbations of leaf structure, observed during the vegetative phase, after high levels of radiation were not so severe as to induce any significant alterations in photosynthetic efficiency. PMID:24883400

  17. Thermally annealed gold nanoparticles for surface-assisted laser desorption ionisation-mass spectrometry of low molecular weight analytes.

    PubMed

    Pilolli, Rosa; Ditaranto, Nicoletta; Di Franco, Cinzia; Palmisano, Francesco; Cioffi, Nicola

    2012-10-01

    Metal nanomaterials have an emerging role in surface-assisted laser desorption ionisation-mass spectrometry (SALDI-MS) providing a useful tool to overcome some limitations intrinsically related to the use of conventional organic matrices in matrix-assisted LDI-MS. In this contribution, the possibility to use a stainless-steel-supported gold nanoparticle (AuNP) film as a versatile platform for SALDI-MS was assessed. A sacrificial anode electrosynthetic route was chosen in order to obtain morphologically controlled core-shell AuNPs; the colloidal AuNPs were, thereafter, drop cast onto a stainless-steel sample plate and the resulting AuNP film was thermally annealed in order to improve its effectiveness as LDI-MS promoter. Spectroscopic characterization of the nanostructured film by X-ray photoelectron spectroscopy was crucial for understanding how annealing induced changes in the surface chemistry and influenced the performance of AuNPs as desorption/ionisation promoter. In particular, it was demonstrated that the post-deposition treatments were essential to enhance the AuNP core/analyte interaction, thus resulting in SALDI-MS spectra of significantly improved quality. The AuNP films were applied to the detection of three different classes of low molecular weight (LMW) analytes, i.e. amino acids, peptides and LMW polymers, in order to demonstrate the versatility of this nanostructured material.

  18. Induction of Hsp70 by desiccation, ionising radiation and heat-shock in the eutardigrade Richtersius coronifer.

    PubMed

    Jönsson, K Ingemar; Schill, Ralph O

    2007-04-01

    The physiology and biochemistry behind the extreme tolerance to desiccation shown by the so-called anhydrobiotic animals represents an exciting challenge to biology. The current knowledge suggests that both carbohydrates and proteins are often involved in protecting the dry cell from damage, or in the repair of induced damage. Tardigrades belong to the most desiccation-tolerant multicellular organisms, but very little research has been reported on the biochemistry behind desiccation tolerance in this group. We quantified the induction of the heat-shock protein Hsp70, a very wide-spread stress protein, in response to desiccation, ionising radiation, and heating, in the anhydrobiotic tardigrade Richtersius coronifer using an immuno-westernblot method. Elevated levels of Hsp70 were recorded after treatment of both heat and ionising radiation, and also in rehydrated tardigrades after a period of desiccation. In contrast, tardigrades in the desiccated (dry) state had reduced Hsp70 levels compared to the non-treated control group. Our results suggest that Hsp70 may be involved in the physiological and biochemical system underlying desiccation (and radiation) tolerance in tardigrades, and that its role may be connected to repair processes after desiccation rather than to biochemical stabilization in the dry state.

  19. Rapid screening method for determination of Ecstasy and amphetamines in urine samples using gas chromatography-chemical ionisation mass spectrometry.

    PubMed

    Pellegrini, M; Rosati, F; Pacifici, R; Zuccaro, R; Romolo, F S; Lopez, A

    2002-04-05

    The need for analytical screening tests more reliable and valid to detect amphetamine and related "designer drugs" in biological samples is becoming critical, due to the increasing diffusion of these drugs on the European illegal market. The most common screening procedures based on immunoassays suffer a number of limitations, including low sensitivity, lack of specificity and limited number of detectable substances. This paper describes a screening method based on gas-chromatography-mass-spectrometry (GC/MS) using positive chemical ionisation (PCI) detection. Methanol was used as reactant gas in the ionisation chamber. Molecular ions of different compounds were monitored, allowing a sensitivity of 5-10 ng/ml with high selectivity. The sensitivity of the method gives positive results in samples taken 48-72 h after intake of one dose of 50-100 mg. The method is simple and rapid. Sample preparation was limited to one liquid-liquid extraction, without any hydrolysis and derivatisation. Hydrolysis is critical to identify metabolites excreted as conjugates. Blank urine samples spiked with known amounts of amphetamine (AM), methylamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethylamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA) and methylenedioxyphenyl-N-methyl-2-butanamine (MBDB) were analysed. The method was successfully tested on real samples of urine from people, whose use of amphetamine was suspected, and results were compared with results obtained with immunoassays.

  20. Internet-based ICRP resource for healthcare providers on the risks and benefits of medical imaging that uses ionising radiation.

    PubMed

    Demeter, S; Applegate, K E; Perez, M

    2016-06-01

    The purpose of the International Commission on Radiological Protection (ICRP) Committee 3 Working Party was to update the 2001 web-based module 'Radiation and your patient: a guide for medical practitioners' from ICRP. The key elements of this task were: to clearly identify the target audience (such as healthcare providers with an emphasis on primary care); to review other reputable sources of information; and to succinctly publish the contribution made by ICRP to the various topics. A 'question-and-answer' format addressing practical topics was adopted. These topics included benefits and risks of imaging using ionising radiation in common medical situations, as well as pertaining to specific populations such as pregnant, breast-feeding, and paediatric patients. In general, the benefits of medical imaging and related procedures far outweigh the potential risks associated with ionising radiation exposure. However, it is still important to ensure that the examinations are clinically justified, that the procedure is optimised to deliver the lowest dose commensurate with the medical purpose, and that consideration is given to diagnostic reference levels for particular classes of examinations. © The International Society for Prosthetics and Orthotics.

  1. Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

    PubMed Central

    Rudd, David; Benkendorff, Kirsten; Voelcker, Nicolas H.

    2015-01-01

    Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. PMID:25786067

  2. Ion recombination correction factor in scanned light-ion beams for absolute dose measurement using plane-parallel ionisation chambers

    NASA Astrophysics Data System (ADS)

    Rossomme, S.; Horn, J.; Brons, S.; Jäkel, O.; Mairani, A.; Ciocca, M.; Floquet, V.; Romano, F.; Rodriguez Garcia, D.; Vynckier, S.; Palmans, H.

    2017-07-01

    Based on international reference dosimetry protocols for light-ion beams, a correction factor (k s) has to be applied to the response of a plane-parallel ionisation chamber, to account for recombination of negative and positive charges in its air cavity before these charges can be collected on the electrodes. In this work, k s for IBA PPC40 Roos-type chambers is investigated in four scanned light-ion beams (proton, helium, carbon and oxygen). To take into account the high dose-rates used with scanned beams and LET-values, experimental results are compared to a model combining two theories. One theory, developed by Jaffé, describes the variation of k s with the ionization density within the ion track (initial recombination) and the other theory, developed by Boag, describes the variation of k s with the dose rate (volume recombination). Excellent agreement is found between experimental and theoretical k s-values. All results confirm that k s cannot be neglected. The solution to minimise k s is to use the ionisation chamber at high voltage. However, one must be aware that charge multiplication may complicate the interpretation of the measurement. For the chamber tested, it was found that a voltage of 300 V can be used without further complication. As the initial recombination has a logarithmic variation as a function of 1/V, the two-voltage method is not applicable to these scanned beams.

  3. Microsatellite analysis for determination of the mutagenicity of extremely low-frequency electromagnetic fields and ionising radiation in vitro.

    PubMed

    Mairs, Robert J; Hughes, Kate; Fitzsimmons, Sara; Prise, Kevin M; Livingstone, Anne; Wilson, Lesley; Baig, Nazia; Clark, Anne Marie; Timpson, Alan; Patel, Gaurang; Folkard, M; Angerson, Wilson J; Boyd, Marie

    2007-01-10

    Extremely low-frequency electromagnetic fields (ELF-EMF) have been reported to induce lesions in DNA and to enhance the mutagenicity of ionising radiation. However, the significance of these findings is uncertain because the determination of the carcinogenic potential of EMFs has largely been based on investigations of large chromosomal aberrations. Using a more sensitive method of detecting DNA damage involving microsatellite sequences, we observed that exposure of UVW human glioma cells to ELF-EMF alone at a field strength of 1 mT (50 Hz) for 12 h gave rise to 0.011 mutations/locus/cell. This was equivalent to a 3.75-fold increase in mutation induction compared with unexposed controls. Furthermore, ELF-EMF increased the mutagenic capacity of 0.3 and 3 Gy gamma-irradiation by factors of 2.6 and 2.75, respectively. These results suggest not only that ELF-EMF is mutagenic as a single agent but also that it can potentiate the mutagenicity of ionising radiation. Treatment with 0.3 Gy induced more than 10 times more mutations per unit dose than irradiation with 3 Gy, indicating hypermutability at low dose.

  4. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida

    PubMed Central

    Cameron, Simon J. S.; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-01-01

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities. PMID:27841356

  5. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida.

    PubMed

    Cameron, Simon J S; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-11-14

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities.

  6. Study on the influence of the B4C layer thickness on the neutron flux and energy distribution shape in multi-electrode ionisation chamber.

    PubMed

    Tymińska, K; Maciak, M; Ośko, J; Tulik, P; Zielczyński, M; Gryziński, M A

    2014-10-01

    A model of a multi-electrode ionisation chamber, with polypropylene electrodes coated with a thin layer of B4C was created within Monte Carlo N-Particle Transport Code (MCNPX) and Fluktuierende Kaskade (FLUKA) codes. The influence of the layer thickness on neutron absorption in B4C and on the neutron spectra in the consecutive intra-electrode gas volumes has been studied using the MCNPX and FLUKA codes. The results will be used for designing the new type of the ionisation chamber.

  7. In situ analysis of Titan's tholins by Laser 2 steps Desorption Ionisation

    NASA Astrophysics Data System (ADS)

    Benilan, Y.; Carrasco, N.; Cernogora, G.; Gazeau, M.; Mahjoub, A.; Szopa, C.; Schwell, M.

    2013-12-01

    The main objective of the whole project developed in collaboration (LISA/LATMOS) is to provide a better understanding of the chemical composition of Titan aerosols laboratory analogs, called tholins, and thereby of their formation pathways. The tholins are produced in the PAMPRE reactor (French acronyme for Aerosols Microgravity Production by Reactives Plasmas) developed at LATMOS. These tholins are generated in levitation (wall effects are thus limited) in a low pressure radiofrequency plasma. Up to now, the determination of the physical and chemical properties of these tholins was achieved after their collection and ex-situ analysis by several methods. Their bulk composition was then determined but their insoluble part is still unknown. Other studies were performed after the transfer of the soluble part of the aerosols to different analytical instruments. Therefore, possible artifacts could have influenced the results. We present the SMARD (a French acronym for Mass Spectrometry of Aerosols by InfraRed Laser Desorption) program. A challenging issue of our work is to perform the soluble and unsoluble parts of PAMPRE tholins' analysis in real time and in situ. The coupling of the PAMPRE reactor to a unique instrument (Single Particle Laser Ablation Mass Spectrometry) developed at LISA should allow determining in real time and in situ the characteristics (chemical composition together with granulometry) of the nanometric aerosols. The later are introduced in the analytical instrument using an aerodynamic lens device. Their detection and aerodynamic diameter are determined using two continuous diode lasers operating at λ = 403 nm. Then, the L2DI (Laser 2 steps Desorption Ionisation) technique is used in order to access to the chemical composition of individual particles: they are vaporized using a 10 μm CO2 pulsed laser and the gas produced is then ionized by a 248 nm KrF Excimer laser. Finally, the molecular ions are analyzed by a 1 m linear time-of-flight mass

  8. X-ray line emission from highly ionised argon and sulphur in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    McGinnity, Paul

    Observations of H-like and He-like argon line emission and associated satellite spectra have been made on the JET (Joint European Torus) tokamak by a Bragg rotorspectrometer and a double crystal monochromator. Similar He-like sulphur measurements have been made on the COMPASS-D (Compact Assembly) tokamak by a Johann curved crystal spectrometer. Recently calculated electron impact excitation rates for He-like ions were used in the derivation of the electron temperature sensitive line ratio G=(Ix+Iy+Iz)/Iw and the electron density sensitive ratio R=Iz/(Ix+Iy), where w, x, y and z are the He-like resonance line, intercombination lines and forbidden line respectively. For S XV the ratios Ik/Iw and Iq/Iw were also calculated, where k and q are Li-like dielectronic satellites to the w line formed by dielectronic recombination and inner shell excitation respectively. Both are electron temperature dependent, the latter also being sensitive to changes in the ionisation balance. The fine structure ratios Ix/Iy and /beta = Ly/alpha 2/Lyα1 were calculated for He-like S XV and H-like Ar XVIII respectively, where Ly/alpha/sb[1,2] are the fine structure components of the H-like Lyman alpha line. Transport modelling was carried out to account for non-coronal conditions in the JET plasma while a near-coronal equilibrium was assumed in the COMPASS-D plasma. Calculated ratios were compared with experimental measurements obtained from JET and COMPASS-D. For higher temperatures, such as during additional heating, the Ar XVII emission shell was found to move of axis, with a subsequent reduction in the G ratio. For S XV good agreement with calculations was found between the measured G and Iq/Iw ratios, indicating that the assumption of near-coronal equilibrium was valid. Lower than expected values of the S XV R ratio were found. After investigation of the atomic physics processes it was concluded that this was due to an unidentified instrumental effect of the Johann spectrometer. An

  9. Neutral and ionised gas around the post-red supergiant IRC +10 420 at AU size scales

    NASA Astrophysics Data System (ADS)

    Oudmaijer, R. D.; de Wit, W. J.

    2013-03-01

    Context. IRC +10 420 is one of the few known massive stars in rapid transition from the red supergiant phase to the Wolf-Rayet or luminous blue variable phase. Aims: The star has an ionised wind and using the Brγ line we assess the mass-loss on spatial scales of ~1 AU. Methods: We present new VLT Interferometer AMBER data which are combined with all other AMBER data present in the literature. The final dataset covers a position angle range of ~180° and baselines up to 110 m. The spectrally dispersed visibilities, differential phases and line flux are conjointly analysed and modelled. We also present the first AMBER/FINITO observations which cover a larger wavelength range and allow us to observe the Na i doublet at 2.2 μm. The data are complemented by X-Shooter data, which provide a higher spectral resolution view. Results: The Brγ emission line and the Na i doublet are both spatially resolved. After correcting the AMBER data for the fact that the lines are not spectrally resolved, we find that Brγ traces a ring with a diameter of 4.18 mas, in agreement with higher spectral resolution data. We consider a geometric model in which the Brγ emission emerges from the top and bottom rings of an hour-glass shaped structure, viewed almost pole-on. It provides satisfactory fits to most visibilities and differential phases. The fact that we detect line emission from a neutral metal like Na i within the ionised region, a very unusual occurrence, suggests the presence of a dense pseudo-photosphere. Conclusions: The ionised wind can be reproduced with a polar wind, which could well have the shape of an hour-glass. Closer in, the resolved Na i emission is found to occur on scales barely larger than the continuum. This fact and that many yellow hypergiants exhibit this comparatively rare emission hints at the presence of a "Yellow" or even "White Wall" in the Hertzsprung-Russell diagram, preventing them from visibly evolving to the blue. Based on observations at ESO, and in

  10. Qualitative and quantitative analysis of Potentilla fulgens roots by NMR, matrix-assisted laser desorption/ionisation with time-of-flight MS, electrospray ionisation MS/MS and HPLC/UV.

    PubMed

    Choudhary, Alka; Radhika, Manukonda; Chatterjee, Anupam; Banerjee, Uttam Chand; Singh, Inder Pal

    2015-01-01

    Potentilla fulgens is a commonly used folk medicine by natives of northeast India, Nepal and Bhutan and is rich in polyphenolic and triterpene constituents. To identify chemomarkers in the roots of P. fulgens by an interplay of (13)C-NMR, matrix-assisted laser desorption/ionisation with time-of-flight (MALDI/TOF) MS, electrospray ionisation (ESI) MS/MS and HPLC/UV. The (13)C-NMR spectrum of crude methanolic extract was recorded in deuterated dimethyl sulphoxide. For MALDI/TOF/MS analysis, 2,5-dihydroxybenzoic acid was used as the matrix. For determination of chemical constituents, two independent simple isocratic HPLC/UV methods for monomeric/oligomeric flavanols and triterpene acids were developed and validated. The (13)C-NMR spectrum of the methanolic extract indicated the presence of B-type oligomeric polyphenolics containing mainly epicatechin/catechin (epicat/cat) and epiafzelechin/afzelechin (epiafz/afz) as the monomeric units. Several isobaric monomeric and oligomeric flavanols and triterpenoids were tentatively identified by MALDI/TOF/MS and ESI/MS/MS. Fourteen compounds (four monomeric and five dimeric flavanols and five triterpene acids) were isolated using repeated column chromatography and semi-preparative HPLC, and were quantitated using HPLC/UV. It is evident from these analyses that roots of P. fulgens contain flavans, including oligomeric flavanols, as major constituents followed by triterpene acids. The methods described can be applied to other Potentilla species to identify their constituents. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Investigation of colloidal graphite as a matrix for matrix-assisted laser desorption/ionisation mass spectrometry of low molecular weight analytes.

    PubMed

    Warren, Alexander D; Conway, Ulric; Arthur, Christopher J; Gates, Paul J

    2016-07-01

    The analysis of low molecular weight compounds by matrix-assisted laser desorption/ionisation mass spectrometry is problematic due to the interference and suppression of analyte ionisation by the matrices typically employed - which are themselves low molecular weight compounds. The application of colloidal graphite is demonstrated here as an easy to use matrix that can promote the ionisation of a wide range of analytes including low molecular weight organic compounds, complex natural products and inorganic complexes. Analyte ionisation with colloidal graphite is compared with traditional organic matrices along with various other sources of graphite (e.g. graphite rods and charcoal pencils). Factors such as ease of application, spectra reproducibility, spot longevity, spot-to-spot reproducibility and spot homogeneity (through single spot imaging) are explored. For some analytes, considerable matrix suppression effects are observed resulting in spectra completely devoid of matrix ions. We also report the observation of radical molecular ions [M(-●) ] in the negative ion mode, particularly with some aromatic analytes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

    PubMed

    Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

    2017-04-01

    Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Rapid assignment of malting barley varieties by matrix-assisted laser desorption-ionisation - Time-of-flight mass spectrometry.

    PubMed

    Šedo, Ondrej; Kořán, Michal; Jakešová, Michaela; Mikulíková, Renata; Boháč, Michal; Zdráhal, Zbyněk

    2016-09-01

    A method for discriminating malting barley varieties based on direct matrix-assisted laser desorption-ionisation - time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting of proteins was developed. Signals corresponding to hordeins were obtained by simple mixing of powdered barley grain with a MALDI matrix solution containing 12.5mgmL(-1) of ferulic acid in an acetonitrile:water:formic acid 50:33:17 v/v/v mixture. Compared to previous attempts at MALDI-TOF mass spectrometric analysis of barley proteins, the extraction and fractionation steps were practically omitted, resulting in a significant reduction in analytical time and costs. The discriminatory power was examined on twenty malting barley varieties and the practicability of the method was tested on sixty barley samples acquired from Pilsner Urquell Brewery. The method is proposed as a rapid tool for variety assignment and purity determination of malting barley that may replace gel electrophoresis currently used for this purpose.

  14. The detection of piroxicam, tenoxicam and their metabolites in equine urine by electrospray ionisation ion trap mass spectrometry.

    PubMed

    McKinney, Andrew R; Suann, Craig J; Stenhouse, Allen M

    2004-01-01

    An investigation has been conducted into the metabolism and urinary excretion of orally administered piroxicam and tenoxicam in the horse. The major component detected in urine after the administration of piroxicam was 5'-hydroxypiroxicam, which was detectable up to 24 h post-administration. Unchanged piroxicam was present only as a minor component. In contrast, unchanged tenoxicam was the major component observed after the administration of tenoxicam, being detectable for 72 h post-administration, while 5'-hydroxytenoxicam was a minor component. Phase II beta-glucuronide conjugation in each case was found to be negligible. The ion trap mass spectral characteristics of piroxicam, tenoxicam, 5'-hydroxypiroxicam and 5'-hydroxytenoxicam under electrospray ionisation conditions were examined in some detail.

  15. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  16. Thermoluminescent properties of Ni and Co doped synthetic, high pressure, high temperature diamonds: application to ionising radiation dosimetry.

    PubMed

    Benabdesselam, M; Iacconi, P; Gheeraert, E; Kanda, H; Lapraz, D; Briand, D

    2002-01-01

    An investigation of the thermoluminescence (TL) properties of high pressure, high temperature (HPHT) synthetic diamond crystals grown under diluted nickel or cobalt as solvent catalysts is reported. After a study of TL properties of 6 different samples, it is shown that a crystal grown with Ni+2%Ti and annealed at 2100 K presents an intense glow peak at around 490 K. This peak is characterised by a broad emission band centred at 530 nm (2.34 eV). This crystal presents a significant, reproducible and linear TL response relative to the absorbed dose up to an X ray air kerma of 10 Gy. All these features make this material suitable for ionising radiation dosimetry. A similar study is made on another crystal grown from pure Co, and a comparative review of the results does show that for dosimetry work, Ni-containing diamonds are more appropriate than those grown from Co catalyst.

  17. Determination and imaging of metabolites from Vitis vinifera leaves by laser desorption/ionisation time-of-flight mass spectrometry.

    PubMed

    Hamm, Gregory; Carré, Vincent; Poutaraud, Anne; Maunit, Benoît; Frache, Gilles; Merdinoglu, Didier; Muller, Jean-François

    2010-02-01

    Analysis of grapevine phytoalexins at the surface of Vitis vinifera leaves has been achieved by laser desorption/ionisation time-of-flight mass spectrometry (LDI-ToFMS) without matrix deposition. This simple and rapid sampling method was successfully applied to map small organic compounds at the surface of grapevine leaves. It was also demonstrated that the laser wavelength is a highly critical parameter. Both 266 and 337 nm laser wavelengths were used but the 266 nm wavelength gave increased spatial resolution and better sensitivity for the detection of the targeted metabolites (resveratrol and linked stilbene compounds). Mass spectrometry imaging of grapevine Cabernet Sauvignon leaves revealed specific locations with respect to Plasmopara viticola pathogen infection or light illumination.

  18. Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging

    PubMed Central

    2011-01-01

    Matrix-Assisted Laser Desorption/Ionisation (MALDI) mass spectrometry imaging (MSI) uses the power of high mass resolution time of flight (ToF) mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples. PMID:21726462

  19. Test beam results of micro channel plates in 'ionisation mode' for the detection of single charged particle and electromagnetic showers

    SciTech Connect

    Barnyakov, A.; Barnyakov, M.; Brianza, L.; Ghezzi, A.; Gotti, C.; Govoni, P.; Martelli, A.; Marzocchi, B.; Pigazzini, S.; Tabarelli de Fatis, T.; Trevisani, N.; Cavallari, F.; Del Re, D.; Gelli, S.; Jorda Lope, C.; Meridiani, P.; Organtini, G.; Paramatti, R.; Pernie, L.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.

    2015-07-01

    IMCP is an R and D project aimed at the exploitation of secondary emission of electrons from the surface of microchannel plates (MCP) for fast timing of showers in high rate environments. The usage of MCPs in 'ionisation' mode has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The fast time resolution of MCPs exceeds anything that has been previously used in calorimeters, and, if exploited effectively, could aid in the event reconstruction at high luminosities. Results from tests with electrons with energies up to 150 GeV of MCP devices with different characteristics will be presented, in particular detection efficiency and time resolution. (authors)

  20. Brain Radiation Information Data Exchange (BRIDE): integration of experimental data from low-dose ionising radiation research for pathway discovery.

    PubMed

    Karapiperis, Christos; Kempf, Stefan J; Quintens, Roel; Azimzadeh, Omid; Vidal, Victoria Linares; Pazzaglia, Simonetta; Bazyka, Dimitry; Mastroberardino, Pier G; Scouras, Zacharias G; Tapio, Soile; Benotmane, Mohammed Abderrafi; Ouzounis, Christos A

    2016-05-11

    The underlying molecular processes representing stress responses to low-dose ionising radiation (LDIR) in mammals are just beginning to be understood. In particular, LDIR effects on the brain and their possible association with neurodegenerative disease are currently being explored using omics technologies. We describe a light-weight approach for the storage, analysis and distribution of relevant LDIR omics datasets. The data integration platform, called BRIDE, contains information from the literature as well as experimental information from transcriptomics and proteomics studies. It deploys a hybrid, distributed solution using both local storage and cloud technology. BRIDE can act as a knowledge broker for LDIR researchers, to facilitate molecular research on the systems biology of LDIR response in mammals. Its flexible design can capture a range of experimental information for genomics, epigenomics, transcriptomics, and proteomics. The data collection is available at: .

  1. Liquid chromatography-flame ionisation detection using a nebuliser/spray chamber interface. Part 1. Design and testing.

    PubMed

    Young, Erepamowei; Smith, Roger M; Sharp, Barry L; Bone, Joanne R

    2012-05-04

    A nebuliser and spray chamber have been used to link a flow injection analyser to a flame ionisation detector, with the potential for the combination to be used as a universal detector for liquid chromatography. The hydrogen and air flows were adjusted to achieve a stable system. The detector responded to both volatile and involatile analytes and to compounds with and without chromophores, including alkanes, alkanols, aromatic amides and acids, phenols, amino-acids and carbohydrates and gave a linear response for many analytes. However, for involatile polar analytes it was necessary to add traces of acid or salt to the carrier stream to obtain a linear response. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Simultaneous determination of alkylphenol ethoxylates and their biotransformation products by liquid chromatography/electrospray ionisation tandem mass spectrometry.

    PubMed

    Jahnke, Annika; Gandrass, Juergen; Ruck, Wolfgang

    2004-04-30

    Reversed-phase LC-MS/MS is used to determine major estrogenic alkylphenol ethoxylates (APEOs) and their biotransformation products. It allows the simultaneous analysis of eight APEOs, alkylphenoxy carboxylates (APECs) and alkylphenols (APs) in sewage treatment plant (STP) effluents in the same extract after solid-phase enrichment on polymeric Oasis HLB. As precursor ions, [APEO + NH4]+, [APEC - H]- and [AP - H]- were monitored. Instrumental limits of detection (LOD) were 2-600 pg, corresponding to sample concentrations of 0.04-12 ng l(-1), without correction for overall method recoveries. Matrix-induced signal suppression during electrospray ionisation (ESI) and extraction as well as overall method recoveries were assessed and the suitability of deuterated surrogates as internal standards was evaluated.

  3. Application of thoron interference as a tool for simultaneous measurement of radon and thoron with a pulse ionisation chamber.

    PubMed

    Tripathi, R M; Sumesh, C G; Vinod Kumar, A; Puranik, V D

    2013-07-01

    Pulse ionisation chamber (PIC)-based monitors measuring radioactive gas radon ((222)Rn) without energy discrimination will have interference due to thoron ((220)Rn) present in the atmosphere. A technique has been developed to use this property of interference for simultaneous measurement of radon and thoron gas. These monitors work on the principle of counting of gross alphas emitted from radon and its progeny. A theoretical model has been developed for the variation of thoron sensitivity with respect to the flow rate of gas through the monitor. The thoron sensitivity of the monitor is found to vary with the flow rate of gas through the monitor. Using this sensitivity, the sampling procedure has been developed and verified for simultaneous measurement of radon and thoron. The PIC-measured radon and thoron concentration using this procedure agrees well with those measured by using standard radon and thoron discriminating monitor.

  4. Role of the resistivity of insulating field emitters on the energy of field-ionised and field-evaporated atoms.

    PubMed

    Arnoldi, L; Silaeva, E P; Vurpillot, F; Deconihout, B; Cadel, E; Blum, I; Vella, A

    2015-12-01

    In order to improve the accuracy of laser atom probe analyses, it is important to understand all the physical processes induced by the combination of the high electrical field and the femtosecond laser beam during field evaporation. New information can be accessed from the energy of evaporated surface atoms or field-ionised atoms of an imaging gas. In order to study the ions energy, we combine La-APT and FIM analyses in a new experimental setup equipped with electrostatic lenses. We report measurements for semiconductors and oxides and we study the influence of the illumination conditions (laser power and wavelength), the evaporation rate, the sample geometry and the tip preparation processes. The results are discussed taking into account the resistive properties of non-metallic samples and the photo-stimulated conductivity. This work clarifies the role of the laser and DC field in the energy deficit of field evaporated ions. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Detection of drugs in lifted cyanoacrylate-developed latent fingermarks using two laser desorption/ionisation mass spectrometric methods.

    PubMed

    Sundar, Latha; Rowell, Frederick

    2014-02-07

    This paper describes a method for lifting cyanoacrylate (CNA)-developed latent fingermarks from a glass surface and the detection of five drugs in lifted marks from fingers that had been in contact with the drugs, using Surface Assisted Laser Desorption Ionisation Time of Flight Mass Spectrometry (SALDI-TOF-MS) or Matrix Assisted Laser Desorption Ionisation TOF-MS (MALDI-TOF-MS). Two drugs of abuse (cocaine and methadone) and three therapeutic drugs (aspirin, paracetamol and caffeine) were used as contact residues. Latent fingermarks spiked with the drugs were subjected to CNA fuming followed by dusting with ARRO SupraNano™ MS black magnetic powder (SALDI-TOF-MS) or 2,5-dihydroxybenzoic acid (DHB) (MALDI-TOF-MS). The dusted mark was then exposed to solvent vapour before lifting with a commercial fingerprint lifting tape following established procedures. The presence of the drugs was then confirmed by direct analysis on the tape without further processing using SALDI- or MALDI-TOF-MS. The black magnetic fingerprint powder provided visual enhancement of the CNA-fingermark while no visual enhancement was observed for marks dusted with DHB powder. Similar [M + H](+) peaks for all the drug analytes were observed for both methods along with some sodium and potassium adducts for SALDI-MS and some major fragment ions but the SALDI signals were generally more intense. Simple exposure to acetone vapour of the CNA-developed marks enabled their effective transfer onto the tape which was crucial for subsequent MS detection of the analytes.

  6. Determination of Cd and Zn by isotope dilution-thermal ionisation mass spectrometry using a sequential analysis procedure.

    PubMed

    Ayoub, Ahmed S; McGaw, Brian A; Midwood, Andrew J

    2002-05-16

    Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) was used to examine the certified Cd and Zn content of 4 Certified Reference Materials (CRMs); 2 soils: GBW07401 and GBW07405, 1 plant CRM060 and an animal tissue SRM1566a. The CRMs were chosen to be of contrasting origin and Cd:Zn content. Three digestion procedures were compared: (i) an open tube aqua regia procedure (ii) microwave digestion using Teflon bombs and (iii) hydrofluoric acid (HF) digestion using PTFE bombs. The Cd and Zn levels obtained using ID-TIMS all fell within the published certified range for the CRMs. This was the case regardless of the digestion procedure used, although HF digestion tended to yield marginally higher levels than the other procedures and in one instance, Cd in GBW07401, was significantly different (P<0.05) from the certified range. A filament loading procedure was developed, to allow sequential analysis of Cd and Zn on the same single filament during thermal ionisation mass spectrometry analysis. The sequential analysis technique was evaluated to ensure that Zn did not fractionate during Cd analysis and there was no inter-element interference. No marked difference in the precision and accuracy of the isotope ratio measurements were obtained from sequential element analyses on the same filament when compared to individual element analyses for a range of standard solutions or for sample digests. The most efficient procedure in terms of costs and productivity for future work of this kind would be a combination of microwave digestion and sequential analysis of Cd and Zn on the same filament.

  7. Follow-up of children exposed to ionising radiation from cardiac catheterisation: the Coccinelle study

    PubMed Central

    Baysson, H.; Nkoumazok, B.; Barnaoui, S.; Réhel, J. L.; Girodon, B.; Milani, G.; Boudjemline, Y.; Bonnet, D.; Laurier, D.; Bernier, M. O.

    2015-01-01

    Cardiac catheterisation has become an essential tool in the diagnosis and treatment of children with a wide variety of congenital and acquired forms of cardiovascular disease. Despite the clear clinical benefit to the patient, radiation exposure from paediatric cardiac catheterisation procedures (CCPs) may be substantial. Given children's greater sensitivity to radiation and the longer life span during which radiation health effects can develop, an epidemiological cohort study, named Coccinelle or ‘Ladybird’ (French acronym for ‘Cohorte sur le risque de cancer après cardiologie interventionnelle pédiatrique’), is carried out in France to evaluate the risks of leukaemia and solid cancers in this population. A total number of 8000 included children are expected. Individual CCP-related doses will be assessed for each child included in the cohort. For each CCP performed, dosimetric parameters (dose–area product, fluoroscopy time and total number of cine frames) are retrieved retrospectively. Organ doses, especially to the lung, the oesophagus and the thyroid, are calculated with PCXMC software. The cohort will be followed up through linkage with French paediatric cancer registries. PMID:25833897

  8. Gold nanoparticles as novel agents for cancer therapy

    PubMed Central

    Jain, S; Hirst, D G; O'Sullivan, J M

    2012-01-01

    Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. This review introduces the field of nanotechnology with a focus on recent gold nanoparticle research which has led to early-phase clinical trials. In particular, the pre-clinical evidence for gold nanoparticles as sensitisers with ionising radiation in vitro and in vivo at kilovoltage and megavoltage energies is discussed. PMID:22010024

  9. The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

    NASA Astrophysics Data System (ADS)

    Husemann, B.; Wisotzki, L.; Sánchez, S. F.; Jahnke, K.

    2013-01-01

    We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 quasi-stellar objects (QSOs) observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data with a new dedicated algorithm. Based on standard emission-line diagnostics we identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of H ii regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is ~10 kpc at a median nuclear [O iii] luminosity of log (L([O iii])/ [ergs-1]) = 42.7 ± 0.15. We show that the ENLR sizes are least a factor of ~2 larger than determined with the Hubble Space Telescope, but are consistent with those of recently reported type 2 QSOs at matching [O iii] luminosities. The ENLR of type 1 and type 2 QSOs therefore appear to follow the same size-luminosity relation. Furthermore, we show for the first time that the ENLR size is much better correlated with the QSO continuum luminosity than with the total/nuclear [O iii] luminosity. We show that ENLR luminosity and radio luminosity are correlated, and argue that radio jets even in radio-quiet QSOs are important for shaping the properties of the ENLR. Strikingly, the kinematics of the ionised gas is quiescent and likely gravitationally driven in the majority of cases and we find only 3 objects with radial gas velocities exceeding >400 km s-1 in specific regions of the EELR that can be associate with radio jets. In general, these are significantly lower outflow velocities and detection rates compared to

  10. Oligomeric carbon and siloxane series observed by matrix-assisted laser desorption/ionisation and laser desorption/ionisation mass spectrometry during the analysis of soot formed in fuel-rich flames.

    PubMed

    Apicella, Barbara; Ciajolo, Anna; Millan, Marcos; Galmes, Carolina; Herod, Alan A; Kandiyoti, Rafael

    2004-01-01

    Oligomeric carbon and siloxane series have been observed by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS), during the analysis of the dichloromethane (DCM)-soluble fractions of condensable material recovered from fuel-rich flames. Laser desorption (LD) spectra showed a pattern of oligomeric dimethyl-siloxane structures with a spacing of 74 u. The siloxane series appears to have originated as contamination of samples by silicone oil used to lubricate connections of polymer tubing. This was confirmed by extracting silicone tubing and silicone grease with DCM followed by MALDI-MS analysis. A series of peaks with a mass spacing of 24 u was also observed, superimposed on the continuum of unresolved organic ions. This oligomeric series appears to correspond to polycyclic aromatics separated by (mainly) ethylene bridges. Thus LD-MS appears to have revealed a series of soot precursors, intermediate between polycyclic aromatics and particulate soot, which was not detected by MALDI-MS. More detailed work is necessary to define these species with precision. Copyright 2004 John Wiley & Sons, Ltd.

  11. Monte Carlo simulation for energy deposition of an ionisation chamber based on the equivalent electron source theory and experimental verification for the theory.

    PubMed

    Ren, Xiaona; Zhang, Aiming; Song, Hailong; Hu, Zunsu; Chen, Mingjun; Wang, Guolin

    2011-07-01

    The main research described in this paper includes three sections. First, research on the response of the stainless steel ball-shaped ionisation chamber by experimental methods. Secondly, calculation of the response of the chamber with the general Monte Carlo EGS4 code in order to compare with the equivalent electron source theory by calculation methods. Finally, calculation of the response of the ionisation chamber with the equivalent electron source theory. The results show that the calculated results of the equivalent electron source theory coincide very well with those of the experiments when the atomic number of the chamber wall is close to one of the gases (such as Ar and Kr), and the calculated results coincide with those of the experiments to a certain extent when the atomic number of the chamber wall is not close to one of the gases (such as He and Xe).

  12. Identification of amino acids by material enhanced laser desorption/ionisation mass spectrometry (MELDI-MS) in positive- and negative-ion mode

    NASA Astrophysics Data System (ADS)

    Hashir, Muhammad Ahsan; Stecher, Guenther; Mayr, Stefan; Bonn, Guenther K.

    2009-01-01

    In the present study, different silica gel modifications were evaluated for their application as target surface for material enhanced laser desorption/ionisation mass spectrometric (MELDI-MS) investigation of amino acids. 4,4'-Azodianiline (ADA-silica) modified silica gel was successfully employed for the qualitative analysis of amino acids in positive- and in negative-ion mode. Further no derivatisation of amino acids was necessary, as the introduced system allowed the direct analysis of targets and delivered spectra with excellent signal intensity and signal-to-noise ratio within a few minutes. The influence of surface chemistry, ionisation mode and the nature of analytes on signal intensity was studied and discussed. Detection limit of 2.10 pg (10 fmol) was achieved by employing ADA-silica in positive-ion mode. Finally, xylem saps from different types of trees were analysed. This proved the high performance and excellent behaviour of the introduced target surface material.

  13. Analysis of nitroaromatic compounds in complex samples using solid-phase microextraction and isotope dilution quantification gas chromatography-electron-capture negative ionisation mass spectrometry.

    PubMed

    Jönsson, S; Gustavsson, L; van Bavel, B

    2007-09-14

    A solid-phase microextraction (SPME) method using gas chromatography-electron-capture negative ionisation mass spectrometry (GC-ECNI-MS) and isotope dilution quantification for the analysis of nitroaromatic compounds in complex, water based samples has been optimised. For ionisation, ECNI was the most sensitive and selective method. SPME was compared to solid-phase extraction (SPE) and found to be more sensitive for these small volume samples. LODs were in the range 0.02-38ngL(-1) for SPME and 6-184ngL(-1) for SPE, respectively. The SPME method was applied on samples in the ngL(-1) level from artificial reed beds treated with sludge containing residues from explosives and pharmaceuticals.

  14. Online antioxidant activity and ultra-performance LC-electrospray ionisation-quadrupole time-of-fight mass spectrometry for chemical fingerprinting of Indian polyherbal formulations.

    PubMed

    Bhandari, Pamita; Kumar, Neeraj; Khan, Shahid M; Bhutani, Kamlesh K

    2016-01-01

    A HPLC-DAD-DPPH method was developed for evaluating the 1, 1-diphenyl-2-picryl hydrazyl free radical scavenging activity of ethylacetate extracts of different polyherbal formulations (draksarista, draksava, lohasava and arvindasava) by using RP-18e column. The ethylacetate extract from polyherbal, 'draksarista' exhibited maximum free radical scavenging activity (99.9 ± 0.38%) followed by draksava (99.8 ± 0.34%), lohasava (98.5 ± 0.30%) and arvindasava (42.3 ± 0.34%) at 100 μg mL(-1). Simultaneously, ultra-performance liquid chromatography coupled with electrospray ionisation-quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) was used to study chemical composition of the ethylacetate extracts of formulations. The characteristic electrospray mass ionisation reveals the dominance of polyphenols and their glycosides in the four polyherbal formulations.

  15. Detection of phenolic oxidation products in cider apple juice by high-performance liquid chromatography electrospray ionisation ion trap mass spectrometry.

    PubMed

    Bernillon, S; Guyot, S; Renard, C M G C

    2004-01-01

    Juice was prepared from cider apples of the cultivar "Kermerrien" under oxidative conditions. After isolation by solid-phase extraction, the phenolic fraction was subjected to high-performance liquid chromatography/electrospray ionisation mass spectrometry. SIM scans were performed at m/z values obtained in model solutions. The oxidation products, resulting from coupling between a molecule of caffeoylquinic acid and caffeoylquinic acid, catechin or dimeric flavan-3-ol, were detected.

  16. DNA double-strand breaks as potential indicators for the biological effects of ionising radiation exposure from cardiac CT and conventional coronary angiography: a randomised, controlled study.

    PubMed

    Geisel, Dominik; Zimmermann, Elke; Rief, Matthias; Greupner, Johannes; Laule, Michael; Knebel, Fabian; Hamm, Bernd; Dewey, Marc

    2012-08-01

    To prospectively compare induced DNA double-strand breaks by cardiac computed tomography (CT) and conventional coronary angiography (CCA). 56 patients with suspected coronary artery disease were randomised to undergo either CCA or cardiac CT. DNA double-strand breaks were assessed in fluorescence microscopy of blood lymphocytes as indicators of the biological effects of radiation exposure. Radiation doses were estimated using dose-length product (DLP) and dose-area product (DAP) with conversion factors for CT and CCA, respectively. On average there were 0.12 ± 0.06 induced double-strand breaks per lymphocyte for CT and 0.29 ± 0.18 for diagnostic CCA (P < 0.001). This relative biological effect of ionising radiation from CCA was 1.9 times higher (P < 0.001) than the effective dose estimated by conversion factors would have suggested. The correlation between the biological effects and the estimated radiation doses was excellent for CT (r = 0.951, P < 0.001) and moderate to good for CCA (r = 0.862, P < 0.001). One day after radiation, a complete repair of double-strand breaks to background levels was found in both groups. Conversion factors may underestimate the relative biological effects of ionising radiation from CCA. DNA double-strand break assessment may provide a strategy for individualised assessments of radiation. • Radiation dose causes concern for both conventional coronary angiography and cardiac CT. • Estimations of the biological effects of ionising radiation may become feasible. • Fewer DNA double-strand breaks are induced by cardiac CT than CCA. • Conversion factors may underestimate the relative effects of ionising radiation from CCA.

  17. Evidence for a Circum-Nuclear and Ionised Absorber in the X-ray Obscured Broad Line Radio Galaxy 3C 445

    NASA Technical Reports Server (NTRS)

    Braito, V.; Reeves, J. N.; Sambruna, R. M.; Gofford, J.

    2012-01-01

    Here we present the results of a Suzaku observation of the Broad Line Radio Galaxy 3C 445. We confirm the results obtained with the previous X-ray observations which unveiled the presence of several soft X-ray emission lines and an overall X-ray emission which strongly resembles a typical Seyfert 2 despite of the optical classification as an unobscured AGN. The broad band spectrum allowed us to measure for the first time the amount of reflection (R approximately 0.9) which together with the relatively strong neutral Fe Ka emission line (EW approximately 100 eV) strongly supports a scenario where a Compton-thick mirror is present. The primary X ray continuum is strongly obscured by an absorber with a column density of NH = 2 - 3 x 10(exp 23) per square centimeter. Two possible scenarios are proposed for the absorber: a neutral partial covering or a mildly ionised absorber with an ionisation parameter log xi approximately 1.0 erg centimeter per second. A comparison with the past and more recent X-ray observations of 3C 445 performed with XMM-Newton and Chandra is presented, which provided tentative evidence that the ionised and outflowing absorber varied. We argue that the absorber is probably associated with an equatorial diskwind located within the parsec scale molecular torus.

  18. High-performance liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry determination of zaleplon in human plasma.

    PubMed

    Zhang, Beibei; Zhang, Zunjian; Tian, Yuan; Xu, Fengguo; Chen, Yun

    2006-02-24

    A sensitive and specific liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry (LC-APCI-MS) method has been developed and validated for the identification and quantification of zaleplon in human plasma using estazolam as an internal standard (IS). After the addition of estazolam and 2.0 M sodium hydroxide solution, plasma samples were extracted with ethyl acetate and then the organic layer was evaporated to dryness. The reconstituted solution of the residue was injected onto a prepacked Shim-pack VP-ODS C18 (250 mm x 2.0 mm i.d.) column and chromatographed with a mobile phase comprised of methanol:water (70:30) at a flow-rate of 0.2 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via atmospheric pressure chemical ionization (APCI) source. The mean standard curve was linear (r = 0.9991) over the concentration range of 0.2-100 ng/ml and had good back-calculated accuracy and precision. The intra-day and inter-day precisions were within 10% relative standard deviation and accuracy ranged from 85% to 115%. The limit of detection was 0.1 ng/ml. The validated LC-APCI-MS method has been used successfully to study zaleplon pharmacokinetic, bioavailability and bioequivalence in 18 adult volunteers.

  19. An investigation of the matrix sensitivity of refinery gas analysis using gas chromatography with flame ionisation detection.

    PubMed

    Ferracci, Valerio; Brown, Andrew S; Harris, Peter M; Brown, Richard J C

    2015-02-27

    The response of a flame ionisation detector (FID) on a gas chromatograph to methane, ethane, propane, i-butane and n-butane in a series of multi-component refinery gas standards was investigated to assess the matrix sensitivity of the instrument. High-accuracy synthetic gas standards, traceable to the International System of Units, were used to minimise uncertainties. The instrument response exhibited a small dependence on the component amount fraction: this behaviour, consistent with that of another FID, was thoroughly characterised over a wide range of component amount fractions and was shown to introduce a negligible bias in the analysis of refinery gas samples, provided a suitable reference standard is employed. No significant effects of the molar volume, density and viscosity of the gas mixtures on the instrument response were observed, indicating that the FID is suitable for the analysis of refinery gas mixtures over a wide range of component amount fractions provided that appropriate drift-correction procedures are employed. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography-atmospheric pressure ionisation mass spectrometry.

    PubMed

    Zöllner, Peter; Mayer-Helm, Bernhard

    2006-12-15

    Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006.

  1. Kinetic transcriptomic approach revealed metabolic pathways and genotoxic-related changes implied in the Arabidopsis response to ionising radiations.

    PubMed

    Gicquel, Morgane; Taconnat, Ludivine; Renou, Jean-Pierre; Esnault, Marie-Andrée; Cabello-Hurtado, Francisco

    2012-10-01

    Plants exposed to ionising radiation (IR) have to face direct and indirect (oxidative stress) deleterious effects whose intensity depends on the dose applied and led to differential genome regulation. Transcriptomic analyses were conducted with CATMA microarray technology on Arabidopsis thaliana plantlets, 2 and 26h after exposure to the IR doses 10Gy and 40Gy. 10Gy treatment seemed to enhance antioxidative compound biosynthetic pathways whereas the 40Gy dose up-regulated ROS-scavenging enzyme genes. Transcriptomic data also highlighted a differential regulation of chloroplast constituent genes depending on the IR dose, 10Gy stimulating and 40Gy down-regulating. This probable 40Gy decrease of photosynthesis could help for the limitation of ROS production and may be coupled with programmed cell death (PCD)/senescence phenomena. Comparisons with previous transcriptomic studies on plants exposed to a 100Gy dose revealed 60 dose-dependent up-regulated genes, including notably cell cycle checkpoints to allow DNA repairing phenomena. Furthermore, the alteration of some cellular structure related gene expression corroborated a probable mitotic arrest after 40Gy. Finally, numerous heat-shock protein and chaperonin genes, known to protect proteins against stress-dependent dysfunction, were up-regulated after IR exposure. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  2. Direct analysis of pharmaceutical tablet formulations using Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging.

    PubMed

    Earnshaw, Caroline J; Carolan, Vikki A; Richards, Don S; Clench, Malcolm R

    2010-06-15

    Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) has been used to directly analyse a range of tablets in order to assess the homogeneity of the active drug compound throughout the excipients contained within the tablets studied. The information gained from the imaging experiments can be used to improve and gain a greater understanding of the manufacturing process; such knowledge will enable improvements in finished product quality to make safer and more efficacious tablet formulations. Commercially available and prescription tablet formulations have been analysed, including aspirin, paracetamol, sildenafil citrate (Viagra(R)) and a batch of tablets in development (tablet X: placebo; 1 mg; 3 mg and 6 mg). MALDI MSI provides semi-quantitative information that is related to ion abundance, therefore Principal Component Analysis (PCA), a multivariate analysis technique, has been used to differentiate between tablets containing different amounts of active drug ingredient. Aspects of sample preparation have also been investigated with regard to tablet shape and texture. The results obtained indicate that MALDI MSI can be used effectively to analyse the spatial distribution of the active pharmaceutical component (API) in pharmaceutical tablet formulations.

  3. Fragmentation of mycosporine-like amino acids by hydrogen/deuterium exchange and electrospray ionisation tandem mass spectrometry.

    PubMed

    Cardozo, Karina H M; Carvalho, Valdemir M; Pinto, Ernani; Colepicolo, Pio

    2006-01-01

    The determination and identification of mycosporine-like amino acids (MAAs) from algae remain a major challenge due to the low concentration. Mass spectrometry (MS) can make an invaluable contribution in the search and identification of MAAs because of its high sensitivity, possibility of coupling with liquid chromatography, and the availability of powerful tandem mass spectrometric techniques. However, the unequivocal determination of the presence and location of important functional groups present on the basic skeleton of the MAAs is often elusive due to their inherent instability under MS conditions. In this study, the use of hydrogen/deuterium (H/D) exchange and electrospray ionisation tandem mass spectrometry (ESI-MS/MS) for characterisation of four MAAs (palythine, asterina, palythinol and shinorine) isolated from the macroalgae Gracilaria tenuistipitata Chang et Xia was investigated. The accurate-mass confirmation of the protonated molecules was performed on a Q-TOF instrument. We demonstrate that employing deuterium labelling in ESI-MS/MS analysis provides a convenient tool for the determination of new MAAs. Although the fragmentation patterns of MAAs were discussed earlier, to our knowledge, this is the first time that mechanisms are proposed.

  4. Chronic low-dose-rate ionising radiation affects the hippocampal phosphoproteome in the ApoE−/− Alzheimer's mouse model

    PubMed Central

    Kempf, Stefan J.; Janik, Dirk; Barjaktarovic, Zarko; Braga-Tanaka, Ignacia; Tanaka, Satoshi; Neff, Frauke; Saran, Anna; Larsen, Martin R.; Tapio, Soile

    2016-01-01

    Accruing data indicate that radiation-induced consequences resemble pathologies of neurodegenerative diseases such as Alzheimer's. The aim of this study was to elucidate the effect on hippocampus of chronic low-dose-rate radiation exposure (1 mGy/day or 20 mGy/day) given over 300 days with cumulative doses of 0.3 Gy and 6.0 Gy, respectively. ApoE deficient mutant C57Bl/6 mouse was used as an Alzheimer's model. Using mass spectrometry, a marked alteration in the phosphoproteome was found at both dose rates. The radiation-induced changes in the phosphoproteome were associated with the control of synaptic plasticity, calcium-dependent signalling and brain metabolism. An inhibition of CREB signalling was found at both dose rates whereas Rac1-Cofilin signalling was found activated only at the lower dose rate. Similarly, the reduction in the number of activated microglia in the molecular layer of hippocampus that paralleled with reduced levels of TNFα expression and lipid peroxidation was significant only at the lower dose rate. Adult neurogenesis, investigated by Ki67, GFAP and NeuN staining, and cell death (activated caspase-3) were not influenced at any dose or dose rate. This study shows that several molecular targets induced by chronic low-dose-rate radiation overlap with those of Alzheimer's pathology. It may suggest that ionising radiation functions as a contributing risk factor to this neurodegenerative disease. PMID:27708245

  5. Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer

    PubMed Central

    Acton, W. Joe; Lanza, Matteo; Agarwal, Bishu; Jürschik, Simone; Sulzer, Philipp; Breiev, Kostiantyn; Jordan, Alfons; Hartungen, Eugen; Hanel, Gernot; Märk, Lukas; Mayhew, Chris A.; Märk, Tilmann D.

    2014-01-01

    The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O+, O2+, NO+ and Kr+ with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios. PMID:25844048

  6. Aqueous phototransformation of zinc pyrithione Degradation kinetics and byproduct identification by liquid chromatography--atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Sakkas, V A; Shibata, K; Yamaguchi, Y; Sugasawa, S; Albanis, T

    2007-03-16

    The photochemical behavior of the antifouling agent zinc pyrithione (ZnPT) was studied in aqueous media of different composition under simulated solar irradiation using a xenon light source. The influence of important constituents of natural water (dissolved organic matter and nitrate) was also examined using a multivariate kinetic model. It was found that photodegradation proceeds via a pseudo first-order reaction. Kinetic experiments were monitored by LC-MS and photolytic half-lives ranging between 9.2 and 15.1 min have been observed. The increasing concentration of dissolved organic matter (DOM) accelerates the photolysis reaction, while the effect of nitrate ions was also positive since it increased the degradation rate, but to a lesser extent. Irradiation of the aqueous ZnPT solutions gave rise to several transformation products that were isolated by means of solid-phase extraction using poly(styrene-divinylbenzene) extraction disks. These byproducts were identified using liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry. Besides 2-pyridinesulfonic-acid, other degradation products formed included pyridine-N-oxide, 2-mercaptopyridine, 2,2'-dithiobis(pyridine-N-oxide), 2,2-dipyridyl disulfide and the pyridine/pyrithione mixed disulfide, 2,2'-dithiobispyridine mono-N-oxide (PPMD).

  7. Rapid and sensitive method for the analysis of carbon monoxide in blood using gas chromatography with flame ionisation detection.

    PubMed

    Sundin, Anna-Maja; Larsson, Jan Erik

    2002-01-05

    In order to measure changes in physiological CO concentrations in blood with good accuracy, a method was developed using gas chromatography with flame ionisation detection (250 degrees C). A nickel catalyst system was fitted to convert CO to methane at 375 degrees C after separation with a molecular sieve column at 35 degrees C. Helium was used as carrier at 30 ml/min. Porcine or human blood (400 microl) was sampled in gastight tubes and treated with sulfuric acid and saponin (800 microl). Accuracy was 1.4% and 1.5% (RSD), respectively. Precision was 2.8% (porcine blood). Limit of detection was 0.01 nmol/ml gas and limit of quantification 12 nmol/ml blood. Calibration was made in the interval 12-514 nmol/ml blood (corresponding to 0.1-6% COHb). Samples were stable for at least a month at +4 degrees C. This paper describes a method with high sensitivity and good accuracy, suitable for analysis of low CO concentrations.

  8. Uptake and translocation of non-ionised pesticides in the emergent aquatic plant parrot feather Myriophyllum aquaticum.

    PubMed

    de Carvalho, Renato F; Bromilow, Richard H; Greenwood, Richard

    2007-08-01

    The uptake of four (14)C-labelled non-ionised compounds, the methyl carbamoyloxime insecticide/nematicide oxamyl and three model phenylureas, from solution by rooted stems of the aquatic plant parrot feather [Myriophyllum aquaticum (Vell.) Verdc], together with translocation to the emergent shoots, was measured over periods of 24 and 48 h. Uptake into the submerged tissues of roots and stem base could be ascribed to two processes: movement into the aqueous phase of cells and then partitioning onto the plant solids. This latter process was related to lipophilicity (as measured by the l-octanol/water partition coefficient, K(ow)) and gave rise to high uptake rates of the most lipophilic compounds. Translocation to shoots was passive and was optimal at log K(ow) approximately 1.8, at which the efficiency of translocation of compound was about 40% of that of water. This optimum log K(ow) was identical to that observed previously in barley, although the translocation efficiency was somewhat less in parrot feather. Solvation parameters were applied to model uptake and translocation of a set of ten compounds by barley with the particular objective of understanding why translocation efficiency is lower at log K(ow) > 1.8. Copyright (c) 2007 Society of Chemical Industry

  9. Thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry using particle suspension matrices.

    PubMed

    Crecelius, Anna; Clench, Malcolm R; Richards, Don S; Parr, Vic

    2002-06-07

    Particle suspension matrices have been successfully utilized for the analysis of tetracycline antibiotics by thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (TLC-MALDI-TOF-MS). Particles of different materials and sizes have been investigated (Co-UFP, TiN, TiO2, Graphite and Silicon) by applying particle suspensions to eluted TLC plates. Mass spectra and mass chromatograms have been recorded directly from the TLC plates. Strong cationization by sodium and potassium was obtained in the positive ion mode, with [M+Na-NH3]+ ions being the predominant signals. The TLC-MALDI mass spectra recorded from graphite suspensions showed the lowest background noise and the highest peak intensities from the range of suspension matrices studied. The mass accuracy from graphite films was improved by adding the peptide Phe-Phe to the graphite suspensions. This allowed internal recalibration of the TLC-MALDI mass spectra acquired during a run. One major potential advantage of TLC-MALDI-TOF-MS has been demonstrated in the analysis of chlortetracycline and tetracycline in a mixture of oxytetracycline, chlortetracycline, tetracycline and minocycline. Examination of the TLC plate prior to MALDI analysis showed only an unresolved spot for chlortetracycline and tetracycline. However by investigation of the MALDI mass spectra and plotting of single ion chromatograms separate peaks for chlortetracycline and tetracycline could be obtained.

  10. Confirmation and 3D profiling of anabolic steroid esters in injection sites using imaging desorption electrospray ionisation (DESI) mass spectrometry.

    PubMed

    de Rijke, Eva; Hooijerink, Dick; Sterk, Saskia S; Nielen, Michel W F

    2013-01-01

    In this study, desorption electrospray ionisation (DESI) linear ion trap tandem mass spectrometry (MS(n)) was applied for the confirmation and three-dimensional profiling of anabolic steroid esters in an injection site of bovine muscle. The spatial resolution of the DESI-MS(n) was demonstrated by scanning hormone esters and marker ink lines drawn at various distances on a microscopic slide at set distances, using an x-scanner with manual y and z adjustment. Tissue slices of bovine muscle injected with a hormone cocktail were analysed. All anabolic steroid esters could be directly detected in the sample and confirmed on the basis of identification points awarded for selected MS/MS transitions according to the performance criteria given in Commission Decision 2002/657/EC. Moreover, the injection site could be mapped by two-dimensional and three-dimensional imaging MS, showing a horizontal and vertical distribution through the muscle tissue. This DESI approach offers potential for analysis of injection sites of steroid esters from illegally treated animals; moreover, direct analysis by ambient imaging DESI-MS still allows conventional extraction and analysis of the whole tissue for further confirmatory or contra-analysis afterwards.

  11. Analysis of oilfield produced waters and production chemicals by electrospray ionisation multi-stage mass spectrometry (ESI-MSn).

    PubMed

    McCormack, P; Jones, P; Hetheridge, M J; Rowland, S J

    2001-10-01

    Large quantities of diverse polar organic chemicals are routinely discharged from oil production platforms in so-called produced waters. The environmental fate of many of these is unknown since few methods exist for their characterisation. Preliminary investigations into the use of multistage electrospray ionisation ion trap mass spectrometry (ESI-MSn) show its potential for the identification and quantification of compounds in specialty oilfield chemicals (corrosion inhibitors, scale inhibitors, biocides and demulsifiers) and produced waters. Multiple stage mass spectrometry (MSn) with both positive and negative ion detection allows high specificity detection and characterisation of a wide range of polar and charged molecules. For example, linear alkylbenzenesulfonates (LAS), alkyldimethylbenzylammonium compounds, 2-alkyl-1-ethylamine-2-imidazolines, 2-alkyl-1-[N-ethylalkylamide]-2-imidazolines and a di-[alkyldimethylammonium-ethyl]ether were all identified and characterised in commercial formulations and/or North Sea oilfield produced waters. The technique should allow the marine environmental effects and fates of some of these polar compounds to be studied.

  12. Comparison of ionisation chamber and semiconductor detector devices for measurement of the dose-width product for panoramic dental units.

    PubMed

    Mitchell, S A; Martin, C J

    2013-06-01

    Doses for panoramic dental radiography are assessed in terms of the dose-width product (DWP) or dose-area product, which gives a measure of the radiation through a whole exposure. The DWP can be measured using a pencil ionisation chamber (IC) similar to that used for computed tomography dose assessment. However, ICs are sensitive to radiation incident from all directions and so backscatter from the image receptor may increase the recorded dose. This study compares measurements performed using four options: a pencil IC mounted straight on the image receptor, the IC mounted with a steel plate to the rear to standardise scatter conditions, the IC mounted with a steel plate and lead collimators in front to minimise the effect of extra-focal radiation, and a Quart Dido employing a one square centimetre semiconductor detector (SD) designed for panoramic measurements. The results indicate that modification of the current method by incorporating a steel plate reduced the measurement dose by 7% on average, but the reduction was greater for units with semiconductor imaging plates. The measurements with the SD agree more closely with the IC with the steel plate to the rear. An IC with a backing plate to standardise scatter or a suitable SD is recommended for measurement on panoramic dental units.

  13. Effect of ionising radiation on polyphenolic content and antioxidant potential of parathion-treated sage (Salvia officinalis) leaves.

    PubMed

    Ben Salem, Issam; Fekih, Sana; Sghaier, Haitham; Bousselmi, Mehrez; Saidi, Mouldi; Landoulsi, Ahmed; Fattouch, Sami

    2013-11-15

    The γ-irradiation effects on polyphenolic content and antioxidant capacity of parathion-pretreated leaves of Salvia officinalis plant were investigated. The analysis of phenolic extracts of sage without parathion showed that irradiation decreased polyphenolic content significantly (p<0.05) by 30% and 45% at 2 and 4kGy, respectively, compared to non-irradiated samples. The same trend was observed for the Trolox equivalent antioxidant capacity (TEAC), as assessed by the anionic DPPH and cationic ABTS radical-scavenging assays. The antioxidant potential decreased significantly (p<0.01) at 2 and 4kGy, by 11-20% and 40-44%, respectively. The results obtained with a pure chlorogenic acid solution confirmed the degradation of phenols; however, its TEAC was significantly (p<0.01) increased following irradiation. Degradation products of parathion formed by irradiation seem to protect against a decline of antioxidant capacity and reduce polyphenolic loss. Ionising radiation was found to be useful in breaking down pesticide residues without inducing significant losses in polyphenols.

  14. Characterisation of a proposed internet synthesis of N,N-dimethyltryptamine using liquid chromatography/electrospray ionisation tandem mass spectrometry.

    PubMed

    Martins, Cláudia P B; Freeman, Sally; Alder, John F; Brandt, Simon D

    2009-08-14

    The psychoactive properties of N,N-dimethyltryptamine (DMT) are known to induce altered states of consciousness in humans. These properties attract great interest from clinical, neuroscientific, clandestine and forensic communities. The Breath of Hope Synthesis was reported on an internet website as a convenient two-step methodology for the preparation of DMT. The analytical characterisation of the first stage was the subject of previous publications by the authors and involved the thermal decarboxylation of tryptophan and the formation of tryptamine. The present study reports on the characterisation of the second step of this procedure which was based on the methylation of tryptamine. This employed methyl iodide and benzyltriethylammonium chloride/sodium hydroxide as a phase transfer catalyst. The reaction product was characterised by liquid chromatography/electrospray ionisation tandem mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry. Quantitative evaluation was carried out in positive multiple reaction monitoring mode (MRM), which included synthesis of the identified reaction products. MRM screening of the product did not lead to the detection of DMT. Instead, 11.1% tryptamine starting material, 21.0% N,N,N-trimethyltryptammonium iodide (TMT) and 47.4% 1-N-methyl-TMT were detected. A 0.5% trace of the monomethylated N-methyltryptamine was also detected. This study demonstrated the impact on product purity of doubtful synthetic methodologies discussed on the internet.

  15. Comparison between measured and calculated ionised concentrations in Mg2+ /ATP, Mg2+ /EDTA and Ca2+ /EGTA buffers; influence of changes in temperature, pH and pipetting errors on the ionised concentrations.

    PubMed

    McGuigan, John A S; Kay, James W; Elder, Hugh Y; Lüthi, Daniel

    2007-03-01

    The apparent dissociation constants (Kapp) and total ligand concentrations ([Ligand]T) from extensive published and unpublished macroelectrode measurements for Mg2+/ATP, Mg2+/EDTA and Ca2+/EGTA buffers have been recalculated. These calculations were made feasible by the introduction of an Excel program which reduced the time of calculation for Kapp and [Ligand]T from over an hour to under five minutes. These estimations of Kapp and [Ligand]T allowed, not only a comparison between measured and calculated ionised magnesium and calcium concentrations ([Mg2+] and [Ca2+]) for Mg2+/ATP, Mg2+/EDTA and Ca2+/EGTA buffers but also a comparison amongst calculated values. Calculated [X2]1 values always differed from measured, and calculated values differed amongst themselves by factors of at least 2. These variations cast doubts on the published absolute values for intracellular [Mg2+] estimated by 31P-NMR and the resting values for [Ca2+] in cells. The allowable range for [X2+] in the buffers and consequently for Kapp and [Ligand]T has not been defined, which introduces uncertainties into published absolute values for [X2+]. This paper shows that an upper limit of +/- 10% deviation from the mean value for [X2+] is attainable. This requires the temperature to be maintained within +/- 0.5 degrees C, pH within +/- 0.01 units and pipetting errors of less than 0.25%. Until internationally defined buffer standards are available, the lack of correlation between measured and calculated [X2+] means that measurement of Kapp and [Ligand]T and hence [X2+] is more reliable than calculation.

  16. Uncertainties in estimating health risks associated with exposure to ionising radiation.

    PubMed

    Preston, R Julian; Boice, John D; Brill, A Bertrand; Chakraborty, Ranajit; Conolly, Rory; Hoffman, F Owen; Hornung, Richard W; Kocher, David C; Land, Charles E; Shore, Roy E; Woloschak, Gayle E

    2013-09-01

    The information for the present discussion on the uncertainties associated with estimation of radiation risks and probability of disease causation was assembled for the recently published NCRP Report No. 171 on this topic. This memorandum provides a timely overview of the topic, given that quantitative uncertainty analysis is the state of the art in health risk assessment and given its potential importance to developments in radiation protection. Over the past decade the increasing volume of epidemiology data and the supporting radiobiology findings have aided in the reduction of uncertainty in the risk estimates derived. However, it is equally apparent that there remain significant uncertainties related to dose assessment, low dose and low dose-rate extrapolation approaches (e.g. the selection of an appropriate dose and dose-rate effectiveness factor), the biological effectiveness where considerations of the health effects of high-LET and lower-energy low-LET radiations are required and the transfer of risks from a population for which health effects data are available to one for which such data are not available. The impact of radiation on human health has focused in recent years on cancer, although there has been a decided increase in the data for noncancer effects together with more reliable estimates of the risk following radiation exposure, even at relatively low doses (notably for cataracts and cardiovascular disease). New approaches for the estimation of hereditary risk have been developed with the use of human data whenever feasible, although the current estimates of heritable radiation effects still are based on mouse data because of an absence of effects in human studies. Uncertainties associated with estimation of these different types of health effects are discussed in a qualitative and semi-quantitative manner as appropriate. The way forward would seem to require additional epidemiological studies, especially studies of low dose and low dose

  17. SU-E-T-150: Brachytherapy QA Employing a High Resolution Liquid Filled Ionisation Chamber Array: Initial Experience and Limitations

    SciTech Connect

    Gainey, M; Kollefrath, M; Bruggmoser, G

    2015-06-15

    Purpose: Verifying a complex 3D brachytherapy dose distribution by measurement is non-trivial. Ideally a photon detector array should be independent of energy and angle, have high spatial resolution and be robust for routine clinical use. Methods: An iridium-192 source was used. A PMMA jig was constructed comprising an outer slab and a central insert with eight milled channels for 1.33mm (outer diameter) steel needles, see figure. All calculations were performed using an empty CT study reconstructing eight virtual needles (QA-CT), using the v2 source model (Elekta AG, Sweden). A high resolution liquid filled ionisation chamber array SRS1000, together with Verisoft software v6.0 (PTW Freiburg, Germany), was used to perform measurements of plans of increasing complexity to evaluate its suitability for device- and patient-specific QA. The dimension of backscatter material was investigated. The patient plan dwell time distribution was entered manually into the QA-CT and the dose distribution was calculated. Results: Our measurements indicate that the array is independent of energy and angle. The resulting measured dose values are linearly interpolated to 2025 values. Shifts of 1mm of the entire needle are readily detectable. Individual dwell position shifts (2.5mm) are also readily measurable. Moreover a dwell time increase of 1 second both in the edge and central region are detectable. Conclusion: The high resolution SRS1000 array is a powerful instrument for brachytherapy QA enabling 977 simultaneous measurements to be performed. Our measurements suggest 60mm of RW3 backscatter material upstream and downstream are sufficient. Local percentage difference analysis is useful for device based QA, normalized relative percentage difference is arguably better for patient specific QA. Automated transfer of patient plan dwell time distribution to the QA plan is required to enable a comprehensive patient QA study to be performed. Moreover the described measurement technique

  18. Fragmentation mechanisms of protonated benzylamines. Electrospray ionisation-tandem mass spectrometry study and ab initio molecular orbital calculations.

    PubMed

    Bourcier, Sophie; Hoppilliard, Yannik

    2003-01-01

    Our research into neurotransmitters in a biological fluid presented an opportunity to investigate the fragmentations under low collision energy characterising benzyl-amines protonated under electrospray ionisation (ESI) conditions in a triple quadrupole mass spectrometer. In this work we present the breakdown graphs of protonated 3,4-dihydroxybenzylamine, DHBAH(+), and 3-methoxy, 4-hydroxybenzylamine, HMBAH(+), at various source temperatures and various pressures in the collision cell, the collision energy varying from 0 to 46 eV in the laboratory frame. Both parent ions eliminate first NH(3) at very low collision energy. The fragmentations of [MH - NH(3)](+) occur at high collision energy and are quite different for DHBAH(+) and HMBAH(+): formation of [MH - NH(3) - H(2)O - CO](+) for the former; formation of the radical cation [MH - NH(3) - CH(3)](+.) for the latter. These fragmentations are interpreted by means of ab initio calculations up to the B3LYP/6-311+G(2d,2p) level of theory. The successive losses of H(2)O and CO involve first the rearrangement in two steps of benzylic ions formed by loss of NH(3) into tropylium ions. The transition states associated with this rearrangement are very high in energy (about 400 kJ mol(-1) above MH(+)) explaining (i). the absence of an ion corresponding to [DHBAH - NH(3) - H(2)O](+). The determining steps associated with the losses of H(2)O and with H(2)O + CO are located lower in energy than the transition states associated with the isomerisation of benzylic ions into tropylium ions; explaining (ii). the formation of the radical cation [MH - NH(3) - CH(3)](+.). The homolytic cleavage of CH(3)-O requires less energy than does the rearrangement.

  19. Identification of Tsetse (Glossina spp.) Using Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry

    PubMed Central

    Hoppenheit, Antje; Murugaiyan, Jayaseelan; Bauer, Burkhard; Steuber, Stephan; Clausen, Peter-Henning; Roesler, Uwe

    2013-01-01

    Glossina (G.) spp. (Diptera: Glossinidae), known as tsetse flies, are vectors of African trypanosomes that cause sleeping sickness in humans and nagana in domestic livestock. Knowledge on tsetse distribution and accurate species identification help identify potential vector intervention sites. Morphological species identification of tsetse is challenging and sometimes not accurate. The matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS) technique, already standardised for microbial identification, could become a standard method for tsetse fly diagnostics. Therefore, a unique spectra reference database was created for five lab-reared species of riverine-, savannah- and forest- type tsetse flies and incorporated with the commercial Biotyper 3.0 database. The standard formic acid/acetonitrile extraction of male and female whole insects and their body parts (head, thorax, abdomen, wings and legs) was used to obtain the flies' proteins. The computed composite correlation index and cluster analysis revealed the suitability of any tsetse body part for a rapid taxonomical identification. Phyloproteomic analysis revealed that the peak patterns of G. brevipalpis differed greatly from the other tsetse. This outcome was comparable to previous theories that they might be considered as a sister group to other tsetse spp. Freshly extracted samples were found to be matched at the species level. However, sex differentiation proved to be less reliable. Similarly processed samples of the common house fly Musca domestica (Diptera: Muscidae; strain: Lei) did not yield any match with the tsetse reference database. The inclusion of additional strains of morphologically defined wild caught flies of known origin and the availability of large-scale mass spectrometry data could facilitate rapid tsetse species identification in the future. PMID:23875040

  20. Towards the integration of matrix assisted laser desorption ionisation mass spectrometry imaging into the current fingermark examination workflow.

    PubMed

    Bradshaw, Robert; Bleay, Stephen; Wolstenholme, Rosalind; Clench, Malcolm Ronald; Francese, Simona

    2013-10-10

    A wide range of fingermark enhancement techniques (FET) is currently employed to visualise latent fingermarks at crime scenes. However, if smudged, partial, distorted or absent in the National Fingerprint Database, crime scene marks may be not useful for identification purposes. In these circumstances, a technology enabling chemical imaging of both endogenous and exogenous species contained within the fingermark could provide additional and associative investigative information, to profile the suspect's activities prior to the crime. Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Imaging (MALDI MSI) has proven to be such a technique, enabling investigative information to be gathered, for example, on what substances the donor has come in contact with and what they have ingested. Nonetheless, to be employed, MALDI MSI has to be validated and its compatibility with FET tested for integration into the standard fingermark examination workflow. For the first time, a direct comparison has been made between the efficiency of a range of FET and MALDI MSI under different conditions. This information will build towards validation of the technology. Also, for the first time, MALDI MSI has been successfully employed as a sequential step following fingermark enhancement using many of the currently employed FET. Additionally, known enhancers have been "re-visited" by combining them with a MALDI matrix, providing both improved fingermark development and chemical species detection via MALDI MSI. The result reported here are good indication in favour of the integration of MALDI MSI into the current fingermark examination workflow for gathering additional investigative information. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  1. Effect of NaCl and NaHCO3 on serum ionised calcium and blood gas status during sprinting.

    PubMed

    Beard, L A; Hinchcliff, K W

    2002-09-01

    Sodium bicarbonate is often administered to horses before racing in an attempt to delay fatigue and improve performance. We examined the effect of acid-base status on serum ionised calcium concentration (iCa) during high intensity exercise in 8 Standardbred mares. In a randomised, blinded, cross-over study, mares were administered each of 3 treatments, NaCl (0.7 g/kg bwt), NaHCO3 (1 g/kg bwt) in 3 l water, or 3 l of water only, 4 h before performing a standardised exercise test to fatigue on a treadmill. Mixed venous blood samples were collected as the horses ran for 5 min at 3 m/s, to fatigue at a predetermined speed (approximately 113% VO2max) and for 5 min at 3 m/s. There was no effect of treatment on time to fatigue (P = 0.744). NaHCO3 attenuated (P<0.05) the exercise-induced decrease in venous pH (mean +/- s.e. 6.97, 6.95 and 7.06 +/- 0.02 at end of sprint for water, NaCl and NaHCO3, respectively). Both serum total calcium concentration (tCa) and iCa increased (P<0.05) with running. NaHCO3 decreased iCa (P<0.05) compared to water; iCa of 1.58 and 1.44 +/- 0.04 mmol/l before exercise and 1.69 and 1.49 +/- 0.05 end sprint, for water and NaHCO3 treatments, respectively. These results demonstrate an effect of NaHCO3 on iCa during exercise. Further study is necessary to determine the effect of alterations in iCa on exercise performance.

  2. Determination of pharmaceutical compounds in skin by imaging matrix-assisted laser desorption/ionisation mass spectrometry.

    PubMed

    Bunch, Josephine; Clench, Malcolm R; Richards, Don S

    2004-01-01

    Matrix-assisted laser desorption/ionisation (MALDI) quadrupole time-of-flight mass spectrometry (Q-TOFMS) has been used to detect and image the distribution of a xenobiotic substance in skin. Porcine epidermal tissue was treated with 'Nizoral', a medicated shampoo containing ketoconazole (+/-)-1-acetyl-4-[p-[[(2R,4S)-2-(2,4-dichlorophenyl)-2-(imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) as active ingredient. Following incubation for 1 h at 37 degrees C all excess formulation was washed from the surface. A cross-section of the drug-treated tissue was then blotted onto a cellulose membrane, precoated in matrix (alpha-cyano-4-hydroxycinnamic acid (CHCA)), by airspray deposition. In separate experiments the tissue surface was treated with Nizoral within a triangular former, and subsequently blotted onto a matrix-coated membrane. Sample membranes were then mounted into the recess of specialised MALDI targets with adhesive tape. All samples were analysed by MALDI-TOFMS using an Applied Biosystem 'Q-star Pulsar i' hybrid Q-TOF mass spectrometer fitted with an orthagonal MALDI ion source and imaging software. Detection of the protonated molecule was readily achievable by this technique. Treatment of the tissue within a template gave rise to images depicting the expected distribution of the drug, demonstrating that this technique is capable of producing spatially useful data. Ion images demonstrating the permeation of the applied compound into the skin were achieved by imaging a cross-sectional imprint of treated tissue. A calibration graph for the determination of ketoconazole was prepared using the sodium adduct of the matrix ion as an internal standard. This enabled construction of a quantitative profile of drug in skin. Conventional haematoxylin and eosin staining and microscopy methods were employed to obtain a histological image of the porcine epidermal tissue. Superimposing the mass spectrometric and histological images appeared to indicate drug

  3. An atmospheric pressure chemical ionisation liquid chromatographic-tandem mass spectrometry method for the analysis of benzodiazepines in urine.

    PubMed

    Dunlop, S; Hayes, K; Leavy, P; Cusack, D; Maguire, R

    2017-10-01

    The objective of this work was to establish an analytical method for the analysis of 7 Benzodiazepines (diazepam, oxazepam, temazepam, nordiazepam, desalkylflurazepam, alprazolam and α-hydroxyalprazolam) in urine specimens taken from drivers suspected of driving under the influence of drugs. The specimen, calibrator and control preparation involved hydrolysis of conjugated benzodiazepines using β-glucuronidase in sodium acetate buffer, with incubation at 60°C for 2h. Specimens were then centrifuged, before being diluted 1 in 5 (total dilution 1 in 10), with 10% acetonitrile in water. Specimens were analysed using a Shimadzu Prominence UPLC coupled to an AB Sciex 4000 QTrap LC-MS-MS. The chromatographic column was a Shim-pack XR ODS 2.2μm. 3.0×50mm column and the mobile phase was a binary gradient system comprising of mobile phase A which was an ammonium formate/formic acid buffer dissolved in water and mobile phase B which was an ammonium formate/formic acid buffer dissolved in Acetonitrile. APCI was selected as the ionisation technique and the MS was operated in MRM mode, monitoring 2 transitions per analyte. The validation of the method is described. The method was found to be linear, accurate and precise (within day and between day) for diazepam, oxazepam, temazepam, nordiazepam, desalkylflurazepam, alprazolam and α-hydroxyalprazolam. The results of 480 cases are reviewed and show that alprazolam use was found in 35% of cases. Use of benzodiazepines resulting in oxazepam, nordiazepam or temazepam were found ca. 70% of cases analysed. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Determination of nivalenol and deoxynivalenol in wheat using liquid chromatography-mass spectrometry with negative ion atmospheric pressure chemical ionisation.

    PubMed

    Razzazi-Fazeli, E; Böhm, J; Luf, W

    1999-08-27

    A new, rapid and sensitive method has been developed for the determination of nivalenol (NIV) and deoxynivalenol (DON) by using HPLC in combination with an atmospheric pressure chemical ionization (APCI)-interface and a single quadrupole mass spectrometer. Different LC and MS parameters have been optimized prior to this in order to obtain better results and sensitivity. The effect of nebulizing temperature on the sensitivity and fragmentation of NIV and DON in an APCI interface was investigated. Also, the influence of the cone voltage on the fragmentation pattern was studied, which was shown to have a tremendous effect. Furthermore, the effect of modifiers such as ammonium acetate, acetic acid and ammonia on the ionisation yield of the above substances have been investigated. The extraction was carried out using acetonitrile-water. A two step purification was then applied on two different Mycosep clean up columns. We have used a modified, rapid and isocratic HPLC method combined with a negative ion APCI-MS for the separation and quantitative determination of NIV and DON in wheat extract. An RP C18 column was used for the separation of selected compounds in wheat extract with water-acetonitrile-methanol (82:9:9, v/v/v) at a flow-rate of 1 ml/min without a split. Calibration curves show good linearity and reproducibility. The detection limit and precision were determined for NIV and DON. Both compounds could be detected down to microg/kg level in wheat using selected ion monitoring of the [M-H]- ions and the main fragments.

  5. Enhanced sample preparation for quantitation of microcystins by matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

    PubMed

    Puddick, Jonathan; Prinsep, Michèle R; Wood, Susanna A; Craig Cary, S; Hamilton, David P

    2012-01-01

    Microcystins (MCs) are a group of cyanotoxins which pose a serious health threat when present in aquatic systems. Quantitative analysis of MCs by matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry has potential for the processing of large numbers of samples quickly and economically. The existing method uses an expensive internal standard and protocols that are incompatible with automated sample preparation and data acquisition. To produce a MALDI-TOF sample preparation technique for the quantitation of MCs that not only maintains reproducibility and sensitivity, but is also compatible with an automated work-flow. Seven different MALDI-TOF sample preparations were assessed for signal reproducibility (coefficient of variation) and sensitivity (method detection limit) using a cost-effective internal standard (angiotensin I). The best preparation was then assessed for its quantitative performance using three different MC congeners ([Dha⁷] MC-LR, MC-RR and MC-YR). The sensitivity of six of the preparations was acceptable, as was the reproducibility for two thin-layer preparations performed on a polished steel target. Both thin-layer preparations could be used with a MALDI-TOF mass spectrometer that automatically acquires data, and one could be used in an automated sample preparation work-flow. Further investigation using the thin-layer spot preparation demonstrated that linear quantification of three different MC congeners was possible. The study demonstrates that with different sample preparation methods and modern instrumentation, large numbers of samples can be analysed rapidly for MCs at low cost. Copyright © 2011 John Wiley & Sons, Ltd.

  6. The formation and evolution of reconnection-driven, slow-mode shocks in a partially ionised plasma

    NASA Astrophysics Data System (ADS)

    Hillier, A.; Takasao, S.; Nakamura, N.

    2016-06-01

    The role of slow-mode magnetohydrodynamic (MHD) shocks in magnetic reconnection is of great importance for energy conversion and transport, but in many astrophysical plasmas the plasma is not fully ionised. In this paper, we use numerical simulations to investigate the role of collisional coupling between a proton-electron, charge-neutral fluid and a neutral hydrogen fluid for the one-dimensional (1D) Riemann problem initiated in a constant pressure and density background state by a discontinuity in the magnetic field. This system, in the MHD limit, is characterised by two waves. The first is a fast-mode rarefaction wave that drives a flow towards a slow-mode MHD shock wave. The system evolves through four stages: initiation, weak coupling, intermediate coupling, and a quasi-steady state. The initial stages are characterised by an over-pressured neutral region that expands with characteristics of a blast wave. In the later stages, the system tends towards a self-similar solution where the main drift velocity is concentrated in the thin region of the shock front. Because of the nature of the system, the neutral fluid is overpressured by the shock when compared to a purely hydrodynamic shock, which results in the neutral fluid expanding to form the shock precursor. Once it has formed, the thickness of the shock front is proportional to ξ i-1.2 , which is a smaller exponent than would be naively expected from simple scaling arguments. One interesting result is that the shock front is a continuous transition of the physical variables of subsonic velocity upstream of the shock front (a c-shock) to a sharp jump in the physical variables followed by a relaxation to the downstream values for supersonic upstream velocity (a j-shock). The frictional heating that results from the velocity drift across the shock front can amount to ~2 per cent of the reference magnetic energy.

  7. The long-term effects of acute exposure to ionising radiation on survival and fertility in Daphnia magna.

    PubMed

    Sarapultseva, Elena I; Dubrova, Yuri E

    2016-10-01

    The results of recent studies have provided strong evidence for the transgenerational effects of parental exposure to ionising radiation and chemical mutagens. However, the transgenerational effects of parental exposure on survival and fertility remain poorly understood. To establish whether parental irradiation can affect the survival and fertility of directly exposed organisms and their offspring, crustacean Daphnia magna were given 10, 100, 1000 and 10,000mGy of acute γ-rays. Exposure to 1000 and 10,000mGy significantly compromised the viability of irradiated Daphnia and their first-generation progeny, but did not affect the second-generation progeny. The fertility of F0 and F1Daphnia gradually declined with the dose of parental exposure and significantly decreased at dose of 100mGy and at higher doses. The effects of parental irradiation on the number of broods were only observed among the F0Daphnia exposed to 1000 and 10,000mGy, whereas the brood size was equally affected in the two consecutive generations. In contrast, the F2 total fertility was compromised only among progeny of parents that received the highest dose of 10,000mGy. We propose that the decreased fertility observed among the F2 progeny of parents exposed to 10,000mGy is attributed to transgenerational effects of parental irradiation. Our results also indicate a substantial recovery of the F2 progeny of irradiated F0Daphnia exposed to the lower doses of acute γ-rays. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Risk of leukaemia mortality from exposure to ionising radiation in US nuclear workers: a pooled case-control study.

    PubMed

    Daniels, Robert D; Bertke, Stephen; Waters, Kathleen M; Schubauer-Berigan, Mary K

    2013-01-01

    To follow-up on earlier studies of the leukaemogenicity of occupational ionising radiation exposure. We conducted a nested case-control analysis of leukaemia mortality in a pooled cohort of US nuclear workers followed through 2005. Each case was matched to four controls on attained age. Exposures were estimated from available records. General relative risk models were used to estimate the excess relative risk (ERR) of leukaemia, excluding chronic lymphocytic (CLL), acute myeloid leukaemia, chronic myeloid leukaemia and CLL while controlling for potential confounders. Preferred exposure lags and time-windows of risks were calculated using joint maximum likelihood. Dose-response was also examined using linear, linear-quadratic, categorical and restricted cubic spline models. There were 369 leukaemia deaths in 105 245 US nuclear workers. The adjusted ERR for non-CLL leukaemia was 0.09 (95% CI -0.17 to 0.65) per 100 mGy. Elevated non-CLL risks were observed from exposures occurring 6-14 years prior to attained age of cases (ERR per 100 mGy=1.9; 95% CI <0 to 8.0). Lagged models indicated non-linearity of risk at very low (<10 mGy) and high (>100 mGy) doses, which contributed to the imprecision of results in linear models. Similar risk attenuation was not evident in time-windows-based models. Risk estimates were in reasonable agreement with previous estimates, with the temporality of non-CLL leukaemia risk as a dominant factor in dose-response analyses. Future research should focus on methods that improve evaluations of the dose-response, particularly in the low-dose range.

  9. Characterisation of exposure to non-ionising electromagnetic fields in the Spanish INMA birth cohort: study protocol.

    PubMed

    Gallastegi, Mara; Guxens, Mònica; Jiménez-Zabala, Ana; Calvente, Irene; Fernández, Marta; Birks, Laura; Struchen, Benjamin; Vrijheid, Martine; Estarlich, Marisa; Fernández, Mariana F; Torrent, Maties; Ballester, Ferrán; Aurrekoetxea, Juan J; Ibarluzea, Jesús; Guerra, David; González, Julián; Röösli, Martin; Santa-Marina, Loreto

    2016-02-18

    Analysis of the association between exposure to electromagnetic fields of non-ionising radiation (EMF-NIR) and health in children and adolescents is hindered by the limited availability of data, mainly due to the difficulties on the exposure assessment. This study protocol describes the methodologies used for characterising exposure of children to EMF-NIR in the INMA (INfancia y Medio Ambiente- Environment and Childhood) Project, a prospective cohort study. Indirect (proximity to emission sources, questionnaires on sources use and geospatial propagation models) and direct methods (spot and fixed longer-term measurements and personal measurements) were conducted in order to assess exposure levels of study participants aged between 7 and 18 years old. The methodology used varies depending on the frequency of the EMF-NIR and the environment (homes, schools and parks). Questionnaires assessed the use of sources contributing both to Extremely Low Frequency (ELF) and Radiofrequency (RF) exposure levels. Geospatial propagation models (NISMap) are implemented and validated for environmental outdoor sources of RFs using spot measurements. Spot and fixed longer-term ELF and RF measurements were done in the environments where children spend most of the time. Moreover, personal measurements were taken in order to assess individual exposure to RF. The exposure data are used to explore their relationships with proximity and/or use of EMF-NIR sources. Characterisation of the EMF-NIR exposure by this combination of methods is intended to overcome problems encountered in other research. The assessment of exposure of INMA cohort children and adolescents living in different regions of Spain to the full frequency range of EMF-NIR extends the characterisation of environmental exposures in this cohort. Together with other data obtained in the project, on socioeconomic and family characteristics and development of the children and adolescents, this will enable to evaluate the complex

  10. La recombinaison et le rayonnement cosmologique

    NASA Astrophysics Data System (ADS)

    Priou, Denis

    2017-03-01

    The last scattering and the recombination epoch, which occurred approximately 380 000 years after the Big Bang, was followed by a period of time, referred to as "dark ages", during which the first stars and the first galaxies were formed in an expanding, dark universe. During nearly 250 millions years, very specific physical processes were possible, due to the interaction between the spin of the proton and the spin of the electron in neutral hydrogen atoms : a phenomenon called "spin flip" could trigger transitions in the hydrogen atoms, resulting in the emission or the absorption of electromagnetic radiation at the specific wavelength of 21,1cm. Four energetic reservoirs are involved to explain the evolution of the Universes during the dark ages : the cosmic microwave background, the kinetic energy of hydrogen atoms, the hyperfine strcuture of the hydrogem atom and the energy produced by the first stars. In this paper is sketched the history of the Universe during the dark ages, the physical processes involved during its main epochs and their observational consequences. The main astronomical observatories dedicated to the detection of these physical processes are presented.

  11. Rapid separation and identification of anthocyanins from flowers of Viola yedoensis and V. prionantha by high-performance liquid chromatography-photodiode array detection-electrospray ionisation mass spectrometry.

    PubMed

    Zhang, Jie; Wang, Liang-Sheng; Gao, Jin-Ming; Xu, Yan-Jun; Li, Lian-Fang; Li, Chong-Hui

    2012-01-01

    Anthocyanins are important plant secondary metabolites. They show strong antioxidant activities and have potential as anti-cancer agents. Viola yedoensis and V. prionantha are traditional Chinese medicines and ornamental plants. However, the anthocyanin compositions of these two species are still unresolved. To develop a rapid and reliable high-performance liquid chromatography (HPLC) method for the separation and identification of anthocyanins from V. yedoensis and V. prionantha. Samples were extracted in methanol-water-formic acid-TFA (70:27:2:1, v/v). HPLC analysis was done on a C(18) column (TSK-GEL ODS-80Ts: 150 × 4.6 mm i.d.). Four solvent systems were tested to optimise the separation of anthocyanins using different gradient separation systems. HPLC-photodiode array detection (DAD) coupled to electrospray ionisation mass spectrometry (ESI-MS) was used to carry out the comprehensive characterisation of anthocyanins. Fourteen anthocyanins were characterised within 40 min with satisfactory peak resolution by a gradient composed of 10% aqueous formic acid and formic acid-acetonitrile-water (10:40:50, v/v). The calibration curve showed an excellent linear regression (r(2)  = 0.9995) and low intra- and inter-day variations (RSD < 3.67%). The detected anthocyanins derived from Dp, Cy, Pt, Mv and Pn, could be divided into three groups: non-acylated glycosides, acetylglycosides and coumaroylglycosides. Anthocyanins distribution exhibited remarkable differences in aglycone levels and acylation patterns. The optimised method was successfully applied for the analysis of 14 anthocyanins from V. yedoensis and V. prionantha. The identification of anthocyanin constitutions is valuable for breeding and will open up new prospects for their medicinal application. Copyright © 2011 John Wiley & Sons, Ltd.

  12. Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes

    PubMed Central

    Horowitz, Y.; Fuks, E.; Datz, H.; Oster, L.; Livingstone, J.; Rosenfeld, A.

    2011-01-01

    Three outstanding effects of ionisation density on the thermoluminescence (TL) mechanisms giving rise to the glow peaks of LiF:Mg,Ti (TLD-100) are currently under investigation: (1) the dependence of the heavy charged particle (HCP) relative efficiency with increasing ionisation density and the effectiveness of its modelling by track structure theory (TST), (2) the behaviour of the TL efficiency, f(D), as a function of photon energy and dose. These studies are intended to promote the development of a firm theoretical basis for the evaluation of relative TL efficiencies to assist in their application in mixed radiation fields. And (3) the shape of composite peak 5 in the glow curve for various HCP types and energies and following high-dose electron irradiation, i.e. the ratio of the intensity of peak 5a to peak 5. Peak 5a is a low-temperature satellite of peak 5 arising from electron-hole capture in a spatially correlated trapping centre/luminescent centre (TC/LC) complex that has been suggested to possess a potential as a solid-state nanodosemeter due to the preferential electron/hole population of the TC/LC at high ionisation density. It is concluded that (1) the predictions of TST are very strongly dependent on the choice of photon energy used in the determination of f(D); (2) modified TST employing calculated values of f(D) at 2 keV is in agreement with 5-MeV alpha particle experimental results for composite peak 5 but underestimates the 1.5-MeV proton relative efficiencies. Both the proton and alpha particle relative TL efficiencies of the high-temperature TL (HTTL) peaks 7 and 8 are underestimated by an order of magnitude suggesting that the HTTL efficiencies are affected by other factors in addition to radial electron dose; (3) the dose–response supralinearity of peaks 7 and 8 change rapidly with photon energy: this behaviour is explained in the framework of the unified interaction model as due to a very strong dependence on photon energy of the relative

  13. Effect of ionising radiation treatment on the specific migration characteristics of packaging-food simulant combinations: effect of type and dose of radiation.

    PubMed

    Zygoura, P D; Paleologos, E K; Kontominas, M G

    2011-05-01

    Migration levels of acetyl tributyl citrate (ATBC) plasticiser from polyvinyl chloride (PVC) film into the European Union specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10 days. Determination of the analyte was performed by applying an analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection. PVC cling film used was subjected to ionising treatment with a [(60)Co] source, as well as to electron-beam irradiation at doses equal to 5, 15 and 25 kGy, with the aim to compare the effect of type and dose of radiation on the specific migration behaviour of PVC. Equilibrium concentrations of acetyl tributyl citrate into the aqueous solvents covered the ranges 173-422 µg l(-1) and 296-513 µg l(-1) for gamma- and electron-irradiated PVC, respectively. Hence, e-beam irradiation resulted in significantly higher ATBC migration compared with gamma treatment. The highest extraction efficiency of the 10% ethanol solution was common in both gamma and e-beam treatments; distilled water demonstrated the lowest migration. Gamma-irradiation at intermediate doses up to 5 kGy produced no statistically significant (p > 0.05) effect on ATBC migration into all three aqueous simulants; however, this does not apply for high-energy electrons. Both ionising treatments were similar in that they resulted in statistically significant (p < 0.05) differences in plasticiser migrating amounts between non-irradiated and irradiated at doses of 15 and 25 kGy samples. Gamma-radiation did not affect the kinetics of plasticiser migration. On the contrary, electron-beam radiation produced shorter equilibration times for all food-simulating solvents tested at 40°C. The above values regarding ATBC migration into aqueous food simulants are far below the European Union restriction (1 mg kg(-1) body weight

  14. Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes.

    PubMed

    Horowitz, Y; Fuks, E; Datz, H; Oster, L; Livingstone, J; Rosenfeld, A

    2011-06-01

    Three outstanding effects of ionisation density on the thermoluminescence (TL) mechanisms giving rise to the glow peaks of LiF:Mg,Ti (TLD-100) are currently under investigation: (1) the dependence of the heavy charged particle (HCP) relative efficiency with increasing ionisation density and the effectiveness of its modelling by track structure theory (TST), (2) the behaviour of the TL efficiency, f(D), as a function of photon energy and dose. These studies are intended to promote the development of a firm theoretical basis for the evaluation of relative TL efficiencies to assist in their application in mixed radiation fields. And (3) the shape of composite peak 5 in the glow curve for various HCP types and energies and following high-dose electron irradiation, i.e. the ratio of the intensity of peak 5a to peak 5. Peak 5a is a low-temperature satellite of peak 5 arising from electron-hole capture in a spatially correlated trapping centre/luminescent centre (TC/LC) complex that has been suggested to possess a potential as a solid-state nanodosemeter due to the preferential electron/hole population of the TC/LC at high ionisation density. It is concluded that (1) the predictions of TST are very strongly dependent on the choice of photon energy used in the determination of f(D); (2) modified TST employing calculated values of f(D) at 2 keV is in agreement with 5-MeV alpha particle experimental results for composite peak 5 but underestimates the 1.5-MeV proton relative efficiencies. Both the proton and alpha particle relative TL efficiencies of the high-temperature TL (HTTL) peaks 7 and 8 are underestimated by an order of magnitude suggesting that the HTTL efficiencies are affected by other factors in addition to radial electron dose; (3) the dose-response supralinearity of peaks 7 and 8 change rapidly with photon energy: this behaviour is explained in the framework of the unified interaction model as due to a very strong dependence on photon energy of the relative

  15. Proteomic profiling of cancer biomarkers.

    PubMed

    Shau, Hungyi; Chandler, G Scott; Whitelegge, Julian P; Gornbein, Jeffrey A; Faull, Kym F; Chang, Helena R

    2003-07-01

    Early detection and correct diagnosis are essential for effective treatment of cancer and patient survival. Complete sequencing of the human genome, and the genomes of other species, provides valuable tools for discerning the genetic abnormalities in cancer. However, differences between cancerous and normal cells reflect more than variations in genetic sequences and abundance of transcribed RNA. Many cancer biomarkers are manifestation of differences in post-transcriptional splicing and/or post-translational modifications. Thus, proteomic tools are being increasingly utilised in the post-genomic era for discovery of new cancer biomarkers. In this paper we will provide an overview of the biomarker discovery process from the proteomic profiling point of view, with emphasis given to the principles that are involved in the process, including the protein identification strategies, and how surface enhanced laser desorption ionisation mass spectrometry fits into the picture. The aim is to provide a resource for the experimental practitioner seeking awareness of the analytical tools that are now available in contemporary cancer research.

  16. Phytosanitation with Ionising Radiation

    USDA-ARS?s Scientific Manuscript database

    This book chapter by Neil Heather and Guy Hallman, in “Pest Management and Phytosanitary Trade Barriers,” CABI Press, covers ionizing irradiation phytosanitary treatments. Although irradiation as an idea and research object has as long a phytosanitary history an any other phytosanitary treatment, c...

  17. Characterisation of poly(alkyl methacrylate)s by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS)

    NASA Astrophysics Data System (ADS)

    Jackson, Anthony T.; Slade, Susan E.; Scrivens, James H.

    2004-11-01

    Electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) has been employed for the characterisation of two poly(alkyl methacrylate) polymers, namely poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PBMA). Collision-induced dissociation (CID) experiments were performed in a quadrupole orthogonal time-of-flight (ToF) tandem mass spectrometer fitted with a nanospray source. Tandem mass spectra from singly, doubly and triply charged precursor ions (with alkali metals used for cationisation of the oligomers) are shown and the data are compared to those previously generated by means of matrix-assisted laser desorption/ionisation-collision-induced dissociation (MALDI-CID). These data indicate that cations with greater ionic radii may yield the most useful structural information as the mass-to-charge ratio of the precursor ion increases, whereas lithium or sodium ions are proposed to be ideal for obtaining spectra from lower molecular weight oligomers. Fragment ions at low mass-to-charge ratios dominate the spectra. Two series of peaks may be used to calculate the masses of the initiating and terminating end groups of the polymer. Ion peaks of greater mass-to-charge ratios form series that may be used to infer sequence information from the polymers.

  18. Determination of ionisation chamber collection efficiency in a swept electron beam by means of thermoluminescent detectors and the "two-voltage" method.

    PubMed

    Van Dam, J; Rijnders, A; Ang, K K; Mellaerts, M; Grobet, P

    1985-06-01

    Two methods for determining the collection efficiency of a 0.6 cm3 thimble ionisation chamber exposed to the swept electron beam of a linear accelerator Therac 20 Saturne (CGR MeV) have been compared. In one method the chamber signal has been compared to that of simultaneously exposed thermoluminescent LiF dosemeters (TLD), in the other the "two-voltage" method of Boag, adapted for swept beams, has been used. By variation of the electron energy between 20 and 13 MeV, of the focus-skin-distance (FSD) between 200 and 100 cm and of the monitor rate between 400 monitor units (m.u.) and 100 m.u. per minute, different values could be produced for the peak charge density M. The collection efficiency of the chamber, operating at a standard voltage of 250 V, decreases from 0.99 to 0.84 for a charge density increasing from 0.3 X 10(-4) C/m3 to 7.5 X 10(-4) C/m3, respectively. The maximum deviation observed between the TLD and the "two-voltage" method adopted for similar M is never more than 2% and mostly smaller than 1%. It can be concluded that, under the present experimental conditions, the calculated ionisation chamber collection efficiency is confirmed by the experimental method using TL dosimetry.

  19. Identification of N-glycans from Ebola virus glycoproteins by matrix-assisted laser desorption/ionisation time-of-flight and negative ion electrospray tandem mass spectrometry

    PubMed Central

    Ritchie, Gayle; Harvey, David J.; Stroeher, Ute; Feldmann, Friederike; Feldmann, Heinz; Wahl-Jensen, Victoria; Royle, Louise; Dwek, Raymond A.; Rudd, Pauline M.

    2012-01-01

    The larger fragment of the transmembrane glycoprotein (GP1) and the soluble glycoprotein (sGP) of Ebola virus were expressed in human embryonic kidney cells and the secreted products were purified from the supernatant for carbohydrate analysis. The N-glycans were released with PNGase F from within sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE) gels. Identification of the glycans was made with normal-phase high-performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionisation mass spectrometry, negative ion electrospray ionisation fragmentation mass spectrometry and exoglycosidase digestion. Most glycans were complex bi-, tri-and tetra-antennary compounds with reduced amounts of galactose. No bisected compounds were detected. Triantennary glycans were branched on the 6-antenna; fucose was attached to the core GlcNAc residue. Sialylated glycans were present on sGP but were largely absent from GP1, the larger fragment of the transmembrane glycoprotein. Consistent with this was the generally higher level of processing of carbohydrates found on sGP as evidenced by a higher percentage of galactose and lower levels of high-mannose glycans than were found on GP1. These results confirm and expand previous findings on partial characterisation of the Ebola virus transmembrane glycoprotein. They represent the first detailed data on carbohydrate structures of the Ebola virus sGP. PMID:20131323

  20. A miniaturised electron ionisation time-of-flight mass spectrometer that uses a unique helium ion removal pulsing technique specifically for gas analysis.

    PubMed

    Qing, Jiang; Huang, Zhengxu; Zhang, Yan; Zhu, Hui; Tan, Guobin; Gao, Wei; Yang, Peng-yuan

    2013-06-21

    A miniaturised reflectron time-of-flight mass spectrometer combined with an electron ionisation ion source has been developed for the analysis of gases. An entirely new helium ion removal pulsing technique in this mass spectrometer is used to achieve an improved performance for the first time. The helium carrier gas, which enters into the source along with the gaseous sample, is simultaneously ionised and then orthogonally introduced into the time-of-fight mass analyser. Once the relatively light helium ions in the ion packet become extremely close to the reflectron plate (B-plate for short in this article), a modulated pulse is instantaneously applied on the B-plate and a negative reflectron voltage is set to the B-plate and lasts for a very short period, during which all the helium ions are directly bumped into the B-plate and subsequently removed. The helium ion removal pulsing technique can efficiently avoid saturation of the micro-channel plate caused by too many helium ions. A compact and durable instrument is designed, which has a mass resolving resolution greater than 400 FWHM for online gas analysis. The technology may also be further developed to remove other ions for TOF mass spectrometry.

  1. Novel characterisation of minor α-linolenic acid isomers in linseed oil by gas chromatography and covalent adduct chemical ionisation tandem mass spectrometry.

    PubMed

    Gómez-Cortés, P; Brenna, J T; Lawrence, P; de la Fuente, M A

    2016-06-01

    Discrimination between polyunsaturated fatty acid isomers with three double bonds is a great challenge, due to structural similarities and similar polarities. In this study, we report the identification of four minor geometrical isomers of α-linolenic acid (ALA) present in linseed oil samples: (9E,12Z,15E)-, (9Z,12Z,15E)-, (9Z,12E,15Z)- and (9E,12Z,15Z)-octadeca-9,12,15-trienoic acids, chromatographically resolved by gas chromatography (GC) using a new and highly polar ionic phase column (SLB-IL111). Gas chromatography-electron ionisation mass spectrometry (GC-EIMS) determined that the four unknown compounds were C18:3 n-3 isomers. The positional 9-12-15 C18:3 configuration was achieved by covalent adduct chemical ionisation tandem mass spectrometry (CACI-MS/MS) while geometrical configuration was established with analytical standards based on relative retention. We hypothesised that these isomers are formed during linseed oil deodorisation and postulate preferred and unfavoured isomerisation pathways of ALA.

  2. Gas-phase dissociation of ionic liquid aggregates studied by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation.

    PubMed

    Fernandes, Ana M; Coutinho, João A P; Marrucho, Isabel M

    2009-01-01

    Positive singly charged ionic liquid aggregates [(C(n)mim)(m+1)(BF(4))(m)](+) (mim = 3-methylimidazolium; n = 2, 4, 8 and 10) and [(C(4)mim)(m+1)(A)(m)](+) (A = Cl(-), BF(4) (-), PF(6) (-), CF(3)SO(3) (-) and (CF(3)SO(2))(2)N(-)) were investigated by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation. The electrospray ionisation mass spectra (ESI-MS) showed the formation of an aggregate with extra stability for m = 4 for all the ionic liquids with the exception of [C(4)mim][CF(3)SO(3)]. ESI-MS-MS and breakdown curves of aggregate ions showed that their dissociation occurred by loss of neutral species ([C(n)mim][A])(a) with a >or= 1. Variable-energy collision induced dissociation of each aggregate from m = 1 to m = 8 for all the ionic liquids studied enabled the determination of E(cm, 1/2) values, whose variation with m showed that the monomers were always kinetically much more stable than the larger aggregates, independently of the nature of cation and anion. The centre-of-mass energy values correlate well with literature data on ionic volumes and interaction and hydrogen bond energies.

  3. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Change in the ionisation state of a near-surface laser-produced aluminium plasma in double-pulse ablation modes

    NASA Astrophysics Data System (ADS)

    Burakov, V. S.; Bokhonov, A. F.; Nedel'ko, M. I.; Tarasenko, N. V.

    2003-12-01

    The near-surface plasma produced upon irradiation of an aluminium target by two successive laser pulses with nonresonance and resonance wavelengths is studied by the spectroscopic and probe-assisted methods. The feasibility of increasing the ion fraction in the laser-produced plasma in double-pulse ablation modes is demonstrated. The conditions are determined under which processes on the surface as well as selective excitation and ionisation in the plasma have a determining effect on the formation of its ionisation state.

  4. Vaginal cancer

    MedlinePlus

    Vaginal cancer; Cancer - vagina; Tumor - vaginal ... Most vaginal cancers occur when another cancer, such as cervical or endometrial cancer , spreads. This is called secondary vaginal cancer. Cancer ...

  5. Chemical analyses of micrometre-sized solids by a miniature laser ablation/ionisation mass spectrometer (LMS)

    NASA Astrophysics Data System (ADS)

    Tulej, Marek; Wiesendanger, Reto; Neuland, Maike; Meyer, Stefan; Wurz, Peter; Neubeck, Anna; Ivarsson, Magnus; Riedo, Valentine; Moreno-Garcia, Pavel; Riedo, Andreas; Knopp, Gregor

    2017-04-01

    Investigation of elemental and isotope compositions of planetary solids with high spatial resolution are of considerable interest to current space research. Planetary materials are typically highly heterogenous and such studies can deliver detailed chemical information of individual sample components with the sizes down to a few micrometres. The results of such investigations can yield mineralogical surface context including mineralogy of individual grains or the elemental composition of of other objects embedded in the sample surface such as micro-sized fossils. The identification of bio-relevant material can follow by the detection of bio-relevant elements and their isotope fractionation effects [1, 2]. For chemical analysis of heterogenous solid surfaces we have combined a miniature laser ablation mass spectrometer (LMS) (mass resolution (m/Dm) 400-600; dynamic range 105-108) with in situ microscope-camera system (spatial resolution ˜2um, depth 10 um). The microscope helps to find the micrometre-sized solids across the surface sample for the direct mass spectrometric analysis by the LMS instrument. The LMS instrument combines an fs-laser ion source and a miniature reflectron-type time-of-flight mass spectrometer. The mass spectrometric analysis of the selected on the sample surface objects followed after ablation, atomisation and ionisation of the sample by a focussed laser radiation (775 nm, 180 fs, 1 kHz; the spot size of ˜20 um) [4, 5, 6]. Mass spectra of almost all elements (isotopes) present in the investigated location are measured instantaneously. A number of heterogenous rock samples containing micrometre-sized fossils and mineralogical grains were investigated with high selectivity and sensitivity. Chemical analyses of filamentous structures observed in carbonate veins (in harzburgite) and amygdales in pillow basalt lava can be well characterised chemically yielding elemental and isotope composition of these objects [7, 8]. The investigation can be

  6. STRAPS v1.0: Evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Topping, David; Allan, James; Alfarra, Rami; Aumont, Bernard

    2017-04-01

    Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA) formation is thought to be hampered by the complexity of the system. While there are fundamental models now available that can simulate the tens of thousands of reactions thought to take place, validation against experiments is highly challenging. Techniques capable of identifying individual molecules such as chromatography are generally only capable of quantifying a subset of the material present, making it unsuitable for a carbon budget analysis. Integrative analytical methods such as the Aerosol Mass Spectrometer (AMS) are capable of quantifying all mass, but because of their inability to isolate individual molecules, comparisons have been limited to simple data products such as total organic mass and O:C ratio. More detailed comparisons could be made if more of the mass spectral information could be used, but because a discrete inversion of AMS data is not possible, this activity requires a system of predicting mass spectra based on molecular composition. In this proof of concept study, the ability to train supervised methods to predict electron impact ionisation (EI) mass spectra for the AMS is evaluated. Supervised Training Regression for the Arbitrary Prediction of Spectra (STRAPS), is not built from first principles. A methodology is constructed whereby the presence of specific mass-to-charge ratio (m/z) channels are fit as a function of molecular structure before the relative peak height for each channel is similarly fit using a range of regression methods. The widely-used AMS mass spectral database is used as a basis for this, using unit mass resolution spectra of laboratory standards. Key to the fitting process is choice of structural information, or molecular fingerprint. Initial results suggest the generic public 'MACCS' fingerprints provide the most accurate trained model when combined with both decision trees and random forests with median

  7. STRAPS v1.0: evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Topping, David O.; Allan, James; Rami Alfarra, M.; Aumont, Bernard

    2017-06-01

    Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA) formation is thought to be hampered by the complexity of the system. While there are fundamental models now available that can simulate the tens of thousands of reactions thought to take place, validation against experiments is highly challenging. Techniques capable of identifying individual molecules such as chromatography are generally only capable of quantifying a subset of the material present, making it unsuitable for a carbon budget analysis. Integrative analytical methods such as the Aerosol Mass Spectrometer (AMS) are capable of quantifying all mass, but because of their inability to isolate individual molecules, comparisons have been limited to simple data products such as total organic mass and the O : C ratio. More detailed comparisons could be made if more of the mass spectral information could be used, but because a discrete inversion of AMS data is not possible, this activity requires a system of predicting mass spectra based on molecular composition. In this proof-of-concept study, the ability to train supervised methods to predict electron impact ionisation (EI) mass spectra for the AMS is evaluated. Supervised Training Regression for the Arbitrary Prediction of Spectra (STRAPS) is not built from first principles. A methodology is constructed whereby the presence of specific mass-to-charge ratio (m/z) channels is fitted as a function of molecular structure before the relative peak height for each channel is similarly fitted using a range of regression methods. The widely used AMS mass spectral database is used as a basis for this, using unit mass resolution spectra of laboratory standards. Key to the fitting process is choice of structural information, or molecular fingerprint. Our approach relies on using supervised methods to automatically optimise the relationship between spectral characteristics and these molecular fingerprints. Therefore

  8. The application of gas chromatography/atmospheric pressure chemical ionisation time-of-flight mass spectrometry to impurity identification in Pharmaceutical Development.

    PubMed

    Bristow, Tony; Harrison, Mark; Sims, Martin

    2010-06-15

    Accurate mass measurement (used to determine elemental formulae) is an essential tool for impurity identification in pharmaceutical development for process understanding. Accurate mass liquid chromatography/mass spectrometry (LC/MS) is used widely for these types of analyses; however, there are still many occasions when gas chromatography (GC)/MS is the appropriate technique. Therefore, the provision of robust technology to provide accurate mass GC/MS (and GC/MS/MS) for this type of activity is essential. In this report we describe the optimisation and application of a newly available atmospheric pressure chemical ionisation (APCI) interface to couple GC to time-of-flight (TOF) MS.To fully test the potential of the new interface the APCI source conditions were optimised, using a number of standard compounds, with a variety of structures, as used in synthesis at AstraZeneca. These compounds were subsequently analysed by GC/APCI-TOF MS. This study was carried out to evaluate the range of compounds that are amenable to analysis using this technique. The range of compounds that can be detected and characterised using the technique was found to be extremely broad and include apolar hydrocarbons such as toluene. Both protonated molecules ([M + H](+)) and radical cations (M(+.)) were observed in the mass spectra produced by APCI, along with additional ion signals such as [M + H + O](+).The technique has been successfully applied to the identification of impurities in reaction mixtures from organic synthesis in process development. A typical mass accuracy of 1-2 mm/zunits (m/z 80-500) was achieved allowing the reaction impurities to be identified based on their elemental formulae. These results clearly demonstrate the potential of the technique as a tool for problem solving and process understanding in pharmaceutical development. The reaction mixtures were also analysed by GC/electron ionisation (EI)-MS and GC/chemical ionisation (CI)-MS to understand the capability of GC

  9. Nuclear energy facilities and cancers.

    PubMed

    Wakeford, R; Berry, R J

    1996-05-01

    Workers employed in the nuclear energy industry and members of the general public living near nuclear facilities are exposed to low levels of ionising radiation as a result of the routine operation of these facilities. For the purposes of radiological protection, it is assumed that low doses of radiation confer a small increased risk of cancer upon the exposed individual and this is a major consideration in setting dose limits for workers and the general public. Quantitative estimates of radiation risk have been derived from epidemiological studies of groups exposed, on average, to high or moderate doses of radiation (such as the Japanese atomic bomb survivors), and appropriate assumptions are made for the application of such estimates to low dose conditions. There have been claims that the risks of cancer in nuclear industry workers, in their children, and in populations living around nuclear facilities have been grossly underestimated. Substantial evidence is now available from the epidemiological study of these groups. Studies of nuclear industry workforces demonstrate that currently accepted risk estimates are at about the right level, although a positive trend of leukaemia mortality with radiation dose, of a magnitude which is compatible with predictions, can be detected in the most statistically powerful workforce studies. The hypothesis that irradiation of fathers before the conception of their children materially increases the risk of childhood leukaemia has been largely discounted since it is biologically implausible and has found no support in studies using data independent of the study which generated the hypothesis. Increased levels of childhood leukaemia have occurred near certain nuclear facilities in the United Kingdom, but it is most unlikely that these are related to exposure to ionising radiation. Recent evidence suggests that these excesses are caused by a rare response to an infectious agent, which is enhanced under the unusual conditions of

  10. The Insidious Nature of "Hard-Core" Alternative Conceptions: Implications for the Constructivist Research Programme of Patterns in High School Students' and Pre-Service Teachers' Thinking about Ionisation Energy

    ERIC Educational Resources Information Center

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2011-01-01

    The present study contributes to the constructivist research programme (RP) into learning science by comparing patterns in responses from two groups of learners--senior high school students and pre-service teachers--in the same educational context (Singapore), to a diagnostic instrument relating to the topic of ionisation energies. This topic is…

  11. The Insidious Nature of "Hard-Core" Alternative Conceptions: Implications for the Constructivist Research Programme of Patterns in High School Students' and Pre-Service Teachers' Thinking about Ionisation Energy

    ERIC Educational Resources Information Center

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2011-01-01

    The present study contributes to the constructivist research programme (RP) into learning science by comparing patterns in responses from two groups of learners--senior high school students and pre-service teachers--in the same educational context (Singapore), to a diagnostic instrument relating to the topic of ionisation energies. This topic is…

  12. Secondary ionisations in a wall-less ion-counting nanodosimeter: quantitative analysis and the effect on the comparison of measured and simulated track structure parameters in nanometric volumes

    NASA Astrophysics Data System (ADS)

    Hilgers, Gerhard; Bug, Marion U.; Gargioni, Elisabetta; Rabus, Hans

    2015-10-01

    The object of investigation in nanodosimetry is the physical characteristics of the microscopic structure of ionising particle tracks, i.e. the sequence of the interaction types and interaction sites of a primary particle and all its secondaries, which reflects the stochastic nature of the radiation interaction. In view of the upcoming radiation therapy with protons and carbon ions, the ionisation structure of the ion track is of particular interest. Owing to limitations in current detector technology, the only way to determine the ionisation cluster size distribution in a DNA segment is to simulate the particle track structure in condensed matter. This is done using dedicated computer programs based on Monte Carlo procedures simulating the interaction of the primary ions with the target. Hence, there is a need to benchmark these computer codes using suitable experimental data. Ionisation cluster size distributions produced in the nanodosimeter's sensitive volume by monoenergetic protons and alpha particles (with energies between 0.1 MeV and 20 MeV) were measured at the PTB ion accelerator facilities. C3H8 and N2 were alternately used as the working gas. The measured data were compared with the simulation results obtained with the PTB Monte-Carlo code PTra [B. Grosswendt, Radiat. Environ. Biophys. 41, 103 (2002); M.U. Bug, E. Gargioni, H. Nettelbeck, W.Y. Baek, G. Hilgers, A.B. Rosenfeld, H. Rabus, Phys. Rev. E 88, 043308 (2013)]. Measured and simulated characteristics of the particle track structure are generally in good agreement for protons over the entire energy range investigated. For alpha particles with energies higher than the Bragg peak energy, a good agreement can also be seen, whereas for energies lower than the Bragg peak energy differences of as much as 25% occur. Significant deviations are only observed for large ionisation cluster sizes. These deviations can be explained by a background consisting of secondary ions. These ions are produced in the

  13. A system for protecting the environment from ionising radiation: selecting reference fauna and flora, and the possible dose models and environmental geometries that could be applied to them.

    PubMed

    Pentreath, R J; Woodhead, D S

    2001-09-28

    In order to demonstrate, explicitly, that the environment can be protected with respect to controlled sources of ionising radiation, it is essential to have a systematic framework within which dosimetry models for fauna and flora can be used. And because of the practical limitations on what could reasonably be modelled and the amount of information that could reasonably be obtained, it is also necessary to limit the application of such models to a 'set' of fauna and flora within a reference' context. This paper, therefore, outlines the factors that will need to be considered to select such 'reference' fauna and flora, and describes some of the factors and constraints necessary to develop the associated dosimetry models. It also describes some of the most basic environmental geometrics within which the dose models could be set in order to make comparisons amongst different radiation sources.

  14. Proteome analysis of Arabidopsis thaliana by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

    PubMed

    Giavalisco, Patrick; Nordhoff, Eckhard; Kreitler, Thomas; Klöppel, Klaus-Dieter; Lehrach, Hans; Klose, Joachim; Gobom, Johan

    2005-05-01

    In the present study we show results of a large-scale proteome analysis of the recently sequenced plant Arabidopsis thaliana. On the basis of a previously published sequential protein extraction protocol, we prepared protein extracts from eight different A. thaliana tissues (primary leaf, leaf, stem, silique, seedling, seed, root, and inflorescence) and analysed these by two-dimensional gel electrophoresis. A total of 6000 protein spots, from three of these tissues, namely primary leaf, silique and seedling, were excised and the contained proteins were analysed by matrix assisted laser desorption/ionisation time of flight mass spectrometry peptide mass fingerprinting. This resulted in the identification of the proteins contained in 2943 spots, which were found to be products of 663 different genes. In this report we present and discuss the methodological and biological results of our plant proteome analysis.

  15. Sensitivity and accuracy of organic matrix-assisted laser desorption and ionisation mass spectrometry of FeCl3 is higher than in in matrix-free approach.

    PubMed

    Radisavljević, Maja; Kamceva, Tina; Vukićević, Iva; Nisavić, Marija; Milovanović, Milan; Petković, Marijana

    2013-01-01

    We compare the quality and reliability of laser desorption and ionisation mass spectra of FeCl3 acquired without the assistance of the matrix with the spectra acquired with different organic matrix molecules. Generally, inorganic salts tend to form clusters upon laser irradiation, the signals of which can be easily distinguished from ions arising from the matrix. In the presence of a matrix, cluster ions are, however, mostly suppressed. We have compared the number of analyte signals, accuracy of determination of isotope composition of the analyte and the sensitivity of FeCl3 detection between different approaches. The results obtained imply that the sensitivity of mass spectrometric analysis of FeCl3 is somewhat higher when matrices are applied than in the matrix-free approach. Among all matrices tested in this work, F20TPP seems to be the most promising for further applications as a matrix for mass spectrometry of inorganic salts.

  16. Determination of patulin in apple and derived products by UHPLC-MS/MS. Study of matrix effects with atmospheric pressure ionisation sources.

    PubMed

    Beltrán, Eduardo; Ibáñez, María; Sancho, Juan Vicente; Hernández, Félix

    2014-01-01

    Sensitive and reliable analytical methodology has been developed for the measurement of patulin in regulated foodstuffs by using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) with triple quadrupole analyser. Solid samples were extracted with ethyl acetate, while liquid samples were directly injected into the chromatographic system after dilution and filtration without any clean-up step. Chromatographic separation was achieved in less than 4min. Electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) sources were evaluated, in order to assess matrix effects. The use of ESI source caused strong signal suppression in samples; however, matrix effect was negligible using APCI, allowing quantification with calibration standards prepared in solvent. The method was validated in four different apple matrices (juice, fruit, puree and compote) at two concentrations at the low μgkg(-1) level. Average recoveries (n=5) ranged from 71% to 108%, with RSDs lower than 14%. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Rapid characterisation and identification of compounds in Saposhnikoviae Radix by high-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry.

    PubMed

    Chen, Luxiao; Chen, Xiangyang; Su, Lei; Jiang, Yanyan; Liu, Bin

    2017-08-18

    Saposhnikoviae Radix (SR), the dried root of Saposhnikovia divaricata (Turcz.) Schischk. (Umbelliferae), is commonly used as a traditional Chinese medicine. In this study, a rapid and accurate method was firstly, developed for the qualitative analysis of SR by high-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry (HPLC-ESI-Q-TOF-MS/MS). A total of 45 compounds were identified or tentatively characterised, including 13 chromones, 28 coumarins and four others. Among them, 16 compounds were identified from SR for the first time. In addition, six chromones reference standards, including two isolated compounds of 3'-O-angeloylhamaudol and norcimifugin from the extraction of SR, were used to study the fragmentation pathways of chromones. The developed method was effective for characterising the compounds of SR, and the results of the study enriched the understanding of the chemical connotation.

  18. Elucidation of the composition of bovine milk fat triacylglycerols using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Mottram, H R; Evershed, R P

    2001-08-17

    Bovine milk fat triacylglycerols (TAGs) have been characterised using high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (HPLC-APCI-MS) and high-temperature gas chromatography-mass spectrometry (GC-MS). The complex nature of the fat meant that prefractionation was necessary to provide simpler fractions for more detailed molecular analyses. Silica thin-layer chromatography gave rise to two fractions, one of which contained predominantly butyric acid containing TAGs. Gel permeation chromatography (GPC) gave rise to 16 fractions, which were subsequently analysed using HPLC-APCI-MS. Twelve of the GPC fractions were also analysed by high-temperature GC-MS using a capillary column coated with a polarisable stationary phase. TAGs present in the fractions were correlated with those in the chromatogram of the whole milk fat through retention time comparison and the use of mass chromatograms. In total, 120 TAGs were identified.

  19. Analysis of trace amounts of carbon dioxide, oxygen and carbon monoxide in nitrogen using dual capillary columns and a pulsed discharge helium ionisation detector.

    PubMed

    Janse van Rensburg, M; Botha, A; Rohwer, E

    2007-10-05

    Gas mixtures of trace amounts of carbon dioxide (CO(2)), dioxygen (O(2)), and carbon monoxide (CO) in dinitrogen (N(2)) were separated and quantified using parallel dual capillary columns and pulsed discharge helium ionisation detection (PDHID). The detection limits (9 x 10(-9) mol mol(-1) for CO(2), 7 x 10(-9) mol mol(-1) for O(2) and 37 x 10(-9) mol mol(-1) for CO) were lower than those reported previously for similar methods. Uncertainties were calculated and results were validated by comparison of the CO and CO(2) results with those obtained using conventional methods. The method was also used to analyse nitrogen, carbon dioxide and carbon monoxide in oxygen.

  20. Importance of direct anthropogenic emissions of formic acid measured by a chemical ionisation mass spectrometer (CIMS) during the Winter ClearfLo Campaign in London, January 2012

    NASA Astrophysics Data System (ADS)

    Bannan, Thomas J.; Bacak, Asan; Muller, Jennifer B. A.; Booth, A. Murray; Jones, Benjamin; Le Breton, Michael; Leather, Kimberley E.; Ghalaieny, Mohamed; Xiao, Ping; Shallcross, Dudley E.; Percival, Carl J.

    2014-02-01

    Formic acid, an ubiquitous trace gas in the atmosphere, was measured using a chemical ionisation mass spectrometer (CIMS) during the winter ClearfLo campaign in London, 2012. Daily calibrations of formic acid gave sensitivities of 3 ion counts s-1 pptv-1 for the complete campaign and a limit of detection of 2 ppt. No correlation with nitric acid was observed, R2 of 0.137, indicating no significant secondary source of formic acid. However, a strong positive correlation with NOx, CO, and production in line with rush hour periods indicated a direct anthropogenic emission of formic acid from vehicle emissions. Peaks of 6.7 ppb of formic acid were observed with a mean of 610 ppt. Global models indicated that this emission source dominates in the northern hemisphere where global models underestimate formic acid most significantly, thus increasing the accuracy of modelling of global formic acid emissions.

  1. The fragmentation pathways of protonated Amiton in the gas phase: towards the structural characterisation of organophosphorus chemical warfare agents by electrospray ionisation tandem mass spectrometry.

    PubMed

    Ellis-Steinborner, Simon; Ramachandran, Aravind; Blanksby, Stephen J

    2006-01-01

    Amiton (O,O-diethyl-S-[2-(diethylamino)ethyl] phosphorothiolate), otherwise known as VG, is listed in schedule 2 of the Chemical Weapons Convention (CWC) and has a structure closely related to VX (O-ethyl-S-(2-diisopropylamino)ethylmethylphosphonothiolate). Fragmentation of protonated VG in the gas phase was performed using electrospray ionisation ion trap mass spectrometry (ESI-ITMS) and revealed several characteristic product ions. Quantum chemical calculations provide the most probable structures for these ions as well as the likely unimolecular mechanisms by which they are formed. The decomposition pathways predicted by computation are consistent with deuterium-labeling studies. The combination of experimental and theoretical data suggests that the fragmentation pathways of VG and analogous organophosphorus nerve agents, such as VX and Russian VX, are predictable and thus ESI tandem mass spectrometry is a powerful tool for the verification of unknown compounds listed in the CWC.

  2. Identification of phenolic constituents in red chicory salads (Cichorium intybus) by high-performance liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry.

    PubMed

    Carazzone, Chiara; Mascherpa, Dora; Gazzani, Gabriella; Papetti, Adele

    2013-06-01

    Phenolic acids and flavonoids extracted from several types of Cichorium intybus var. silvestre salads ("Chioggia", "Treviso", "Treviso tardivo", and "Verona") were characterised by high-performance liquid chromatography-electrospray ionisation/mass spectrometry. Among the 64 compounds detected, several hydroxycinnamic acid derivatives including 8 mono- and dicaffeoylquinic acids, 3 tartaric acid derivatives, 31 flavonol and 2 flavone glycosides, as well as 10 anthocyanins were characterised based on UV spectra and MS(n) fragmentation patterns. Furthermore, several isomers of caffeic acid derivatives were distinguished for the first time by their specific mass spectral data. This is the first study reporting the glycosylation type and position of mono- and diglycosylated flavonoids in red salads.

  3. Ionisation potential theorem in the presence of the electric field: Assessment of range-separated functional in the reproduction of orbital and excitation energies

    NASA Astrophysics Data System (ADS)

    Borpuzari, Manash Protim; Boruah, Abhijit; Kar, Rahul

    2016-04-01

    Recently, the range-separated density functionals have been reported to reproduce gas phase orbital and excitation energies with good accuracy. In this article, we have revisited the ionisation potential theorem in the presence of external electric field. Numerical results on six linear molecules are presented and the performance of the range-separated density functionals in reproducing highest occupied molecular orbital (HOMO) energies, LUMO energies, HOMO-LUMO gaps in the presence of the external electric field is assessed. In addition, valence and Rydberg excitation energies in the presence of the external electric field are presented. It is found that the range-separated density functionals reproduce orbital and excitation energies accurately in the presence of the electric field. Moreover, we have performed fractional occupation calculation using cubic spline equation and tried to explain the performance of the functional.

  4. Looking into individual coffee beans during the roasting process: direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases.

    PubMed

    Hertz-Schünemann, Romy; Streibel, Thorsten; Ehlert, Sven; Zimmermann, Ralf

    2013-09-01

    A micro-probe (μ-probe) gas sampling device for on-line analysis of gases evolving in confined, small objects by single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) was developed. The technique is applied for the first time in a feasibility study to record the formation of volatile and flavour compounds during the roasting process within (inside) or in the direct vicinity (outside) of individual coffee beans. A real-time on-line analysis of evolving volatile and semi-volatile organic compounds (VOC and SVOC) as they are formed under the mild pyrolytic conditions of the roasting process was performed. The soft-ionisation mass spectra depict a molecular ion signature, which is well corresponding with the existing knowledge of coffee roasting and evolving compounds. Additionally, thereby it is possible to discriminate between Coffea arabica (Arabica) and Coffea canephora (Robusta). The recognized differences in the roasting gas profiles reflect the differences in the precursor composition of the coffee cultivars very well. Furthermore, a well-known set of marker compounds for Arabica and Robusta, namely the lipids kahweol and cafestol (detected in their dehydrated form at m/z 296 and m/z 298, respectively) were observed. If the variation in time of different compounds is observed, distinctly different evolution behaviours were detected. Here, phenol (m/z 94) and caffeine (m/z 194) are exemplary chosen, whereas phenol shows very sharp emission peaks, caffeine do not have this highly transient behaviour. Finally, the changes of the chemical signature as a function of the roasting time, the influence of sampling position (inside, outside) and cultivar (Arabica, Robusta) is investigated by multivariate statistics (PCA). In summary, this pilot study demonstrates the high potential of the measurement technique to enhance the fundamental knowledge of the formation processes of volatile and semi-volatile flavour compounds inside the individual coffee bean.

  5. Predicted ionisation in mitochondria and observed acute changes in the mitochondrial transcriptome after gamma irradiation: a Monte Carlo simulation and quantitative PCR study.

    PubMed

    Kam, Winnie Wai-Ying; McNamara, Aimee L; Lake, Vanessa; Banos, Connie; Davies, Justin B; Kuncic, Zdenka; Banati, Richard B

    2013-11-01

    It is a widely accepted that the cell nucleus is the primary site of radiation damage while extra-nuclear radiation effects are not yet systematically included into models of radiation damage. We performed Monte Carlo simulations assuming a spherical cell (diameter 11.5 μm) modelled after JURKAT cells with the inclusion of realistic elemental composition data based on published literature. The cell model consists of cytoplasm (density 1g/cm(3)), nucleus (diameter 8.5 μm; 40% of cell volume) as well as cylindrical mitochondria (diameter 1 μm; volume 0.5 μm(3)) of three different densities (1, 2 and 10 g/cm(3)) and total mitochondrial volume relative to the cell volume (10, 20, 30%). Our simulation predicts that if mitochondria take up more than 20% of a cell's volume, ionisation events will be the preferentially located in mitochondria rather than in the cell nucleus. Using quantitative polymerase chain reaction, we substantiate in JURKAT cells that human mitochondria respond to gamma radiation with early (within 30 min) differential changes in the expression levels of 18 mitochondrially encoded genes, whereby the number of regulated genes varies in a dose-dependent but non-linear pattern (10 Gy: 1 gene; 50 Gy: 5 genes; 100 Gy: 12 genes). The simulation data as well as the experimental observations suggest that current models of acute radiation effects, which largely focus on nuclear effects, might benefit from more systematic considerations of the early mitochondrial responses and how these may subsequently determine cell response to ionising radiation.

  6. Qualitative analysis of Copaifera oleoresin using comprehensive two-dimensional gas chromatography and gas chromatography with classical and cold electron ionisation mass spectrometry.

    PubMed

    Wong, Yong Foo; Uekane, Thais M; Rezende, Claudia M; Bizzo, Humberto R; Marriott, Philip J

    2016-12-16

    Improved separation of both sesquiterpenes and diterpenic acids in Copaifera multijuga Hayne oleoresin, is demonstrated by using comprehensive two-dimensional gas chromatography (GC×GC) coupled to accurate mass time-of-flight mass spectrometry (accTOFMS). GC×GC separation employs polar phases (including ionic liquid phases) as the first dimension ((1)D) column, combined with a lower polarity (2)D phase. Elution temperatures (Te) of diterpenic acids (in methyl ester form, DAME) increased as the (1)D McReynolds' polarity value of the column phase decreased. Since Te of sesquiterpene hydrocarbons decreased with increased polarity, the very polar SLB-IL111 (1)D phase leads to excessive peak broadening in the (2)D apolar phase due to increased second dimension retention ((2)tR). The combination of SLB-IL59 with a nonpolar column phase was selected, providing reasonable separation and low Te for sesquiterpenes and DAME, compared to other tested column sets, without excessive (2)tR. Identities of DAME were aided by both soft (30eV) electron ionisation (EI) accurate mass TOFMS analysis and supersonic molecular beam ionisation (cold EI) TOFMS, both which providing less fragmentation and increased relative abundance of molecular ions. The inter-relation between EI energies, emission current, signal-to-noise and mass error for the accurate mass measurement of DAME are reported. These approaches can be used as a basis for conducting of GC×GC with soft EI accurate mass measurement of terpenes, particularly for unknown phytochemicals. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Sorption/desorption of non-hydrophobic and ionisable pharmaceutical and personal care products from reclaimed water onto/from a natural sediment.

    PubMed

    Martínez-Hernández, Virtudes; Meffe, Raffaella; Herrera, Sonia; Arranz, Elena; de Bustamante, Irene

    2014-02-15

    In the present work, the sorption of pharmaceutical and personal care products (PPCPs) (acetaminophen, atenolol, carbamazepine, caffeine, naproxen and sulphamethoxazole) onto the natural organic matter (NOM) and the inorganic surfaces of a natural sandy loam sediment was quantified separately. The quantification was based on the PPCP charge, their degree of ionisation, their octanol-water partitioning coefficient (KOW) and the sediment organic carbon fraction (ƒOC). PPCP desorption from the sediment was examined under conditions of infiltrating water containing a high concentration of inorganic ions (mimicking infiltrating reclaimed water), and a low concentration (and smaller diversity) of inorganic ions (mimicking rainwater infiltration). Batch tests were performed using a sediment/water ratio of 1:4 and a PPCP initial concentration ranging from 1 to 100 μg L(-1). The results showed the type and degree of PPCP ionisation to strongly influence the sorption of these compounds onto the sediment. The sorption of cationic species onto the sediment was higher than that of anionic species and mostly reversible; the sorption of neutral species was negligible. The anionic species sorbed less onto the sediment, but also desorbed less easily. More than 70% of the total sorption was due to interaction with mineral surfaces. This holds especially true for cationic species (atenolol and caffeine) which sorption was enhanced by the negative surface charge of the sediment. The presence of inorganic ions had no impact on the desorption of the PPCPs from the sediment. According to the calculated percentages of removal, the mobility followed the order: carbamazepine>acetaminophen>naproxen>atenolol>sulfamethoxazole>caffeine. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. A comparison of overload behaviour for some sub 2 μm totally porous and sub 3 μm shell particle columns with ionised solutes.

    PubMed

    Fallas, Morgane M; Buckenmaier, Stephan M C; McCalley, David V

    2012-04-27

    The overloading performance of some 2.7 μm shell and sub 2 μm totally porous columns, including one pair manufactured from similar materials with similar bonding chemistries, was compared using strongly acidic and basic probe compounds. In general, the capacity of shell particles was not greatly reduced, despite containing a smaller porous volume. Nevertheless, at low pH, both types of column were overloaded by only small concentrations of ionised solute. Considerable improvement could be gained by increasing the buffer concentration, although sensitivity in mass spectrometric detection may be compromised. The capacity of columns of different internal diameter may not be directly compared merely by scaling the injection volumes, as it is possible that the sample is not homogeneously distributed across the column radius, especially in larger diameter columns, where the sample may travel preferentially through a central core of the packing. A totally porous charged surface hybrid phase gave much improved loading properties of the basic probe in low ionic strength mobile phases such as formic acid, often used in mass spectrometry. However, its relative advantage over conventional phases was reduced as the mobile phase ionic strength was increased. Furthermore, acidic compounds may give tailing on this phase. At pH 7, all columns tested showed evidence of interaction with ionised silanols; peak shapes improved as the buffer concentration was increased. Column efficiency first increased and then decreased as solute concentration was increased at constant buffer concentration, which can be attributed to the decreasing proportion of solute molecules retained by the ion exchange process.

  9. Analysis of peptides and protein digests by reversed phase high performance liquid chromatography-electrospray ionisation mass spectrometry using neutral pH elution conditions.

    PubMed

    Yang, Yuanzhong; Boysen, Reinhard I; Chowdhury, Jamil; Alam, Asif; Hearn, Milton T W

    2015-05-04

    In this study, the advantages of carrying out the analysis of peptides and tryptic digests of proteins under gradient elution conditions at pH 6.5 by reversed-phase liquid chromatography (RP-HPLC) and in-line electrospray ionisation mass spectrometry (ESI-MS) are documented. For these RP separations, a double endcapped, bidentate anchored n-octadecyl wide pore silica adsorbent was employed in a capillary column format. Compared to the corresponding analysis of the same peptides and protein tryptic digests using low pH elution conditions for their RP-HPLC separation, this alternative approach provides improved selectivity and more efficient separation of these analytes, thus allowing a more sensitive identification of proteins at different abundance levels, i.e. more tryptic peptides from the same protein could be confidently identified, enabling higher sequence coverage of the protein to be obtained. This approach was further evaluated with very complex tryptic digests derived from a human plasma protein sample using an online two-dimensional (2D) strong cation-exchange (SCX)-RP-HPLC-ESI-MS/MS system. Again, at pH 6.5, with mobile phases of different compositions, improved chromatographic selectivities were obtained, concomitant with more sensitive on-line electrospray ionisation tandem mass spectrometric (ESI-MS/MS) analysis. As a consequence, more plasma proteins could be confidently identified, highlighting the potential of these RP-HPLC methods with elution at pH 6.5 to extend further the scope of proteomic investigations. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Ionising radiation immediately impairs synaptic plasticity-associated cytoskeletal signalling pathways in HT22 cells and in mouse brain: an in vitro/in vivo comparison study.

    PubMed

    Kempf, Stefan J; Buratovic, Sonja; von Toerne, Christine; Moertl, Simone; Stenerlöw, Bo; Hauck, Stefanie M; Atkinson, Michael J; Eriksson, Per; Tapio, Soile

    2014-01-01

    Patients suffering from brain malignancies are treated with high-dose ionising radiation. However, this may lead to severe learning and memory impairment. Preventive treatments to minimise these side effects have not been possible due to the lack of knowledge of the involved signalling pathways and molecular targets. Mouse hippocampal neuronal HT22 cells were irradiated with acute gamma doses of 0.5 Gy, 1.0 Gy and 4.0 Gy. Changes in the cellular proteome were investigated by isotope-coded protein label technology and tandem mass spectrometry after 4 and 24 hours. To compare the findings with the in vivo response, male NMRI mice were irradiated on postnatal day 10 with a gamma dose of 1.0 Gy, followed by evaluation of the cellular proteome of hippocampus and cortex 24 hours post-irradiation. Analysis of the in vitro proteome showed that signalling pathways related to synaptic actin-remodelling were significantly affected at 1.0 Gy and 4.0 Gy but not at 0.5 Gy after 4 and 24 hours. We observed radiation-induced reduction of the miR-132 and Rac1 levels; miR-132 is known to regulate Rac1 activity by blocking the GTPase-activating protein p250GAP. In the irradiated hippocampus and cortex we observed alterations in the signalling pathways similar to those in vitro. The decreased expression of miR-132 and Rac1 was associated with an increase in hippocampal cofilin and phospho-cofilin. The Rac1-Cofilin pathway is involved in the modulation of synaptic actin filament formation that is necessary for correct spine and synapse morphology to enable processes of learning and memory. We suggest that acute radiation exposure leads to rapid dendritic spine and synapse morphology alterations via aberrant cytoskeletal signalling and processing and that this is associated with the immediate neurocognitive side effects observed in patients treated with ionising radiation.

  11. On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry.

    PubMed

    Liljegren, Gustav; Dahlin, Andreas; Zettersten, Camilla; Bergquist, Jonas; Nyholm, Leif

    2005-10-01

    A novel method for the manufacturing of microchips for on-chip combinations of electrochemistry (EC) and sheathless electrospray ionisation mass spectrometry (ESI-MS) is described. The technique, which does not require access to clean-room facilities, is based on the incorporation of an array of gold microcoil electrodes into a poly(dimethylsiloxane)(PDMS) microflow channel equipped with an integrated graphite based sheathless ESI emitter. Electrochemical measurements, which were employed to determine the electroactive area of the electrodes and to test the microchips, show that the manufacturing process was reproducible and that the important interelectrode distance in the electrochemical cell could to be adequately controlled. The EC-ESI-MS device was evaluated based on the ESI-MS detection of the oxidation products of dopamine. The results demonstrate that the present on-chip approach enables full potentiostatic control of the electrochemical cell and the attainment of very short transfer times between the electrochemical cell and the electrospray emitter. The transfer times were 0.6 and 1.2 s for flow rates of 1.0 and 0.5 microL min(-1), respectively, while the electrochemical conversion efficiency of the electrochemical cell was found to be 30% at a flow rate of 0.5 microL min(-1). To decouple the electrochemical cell from the ESI-MS high voltage and to increase the user-friendliness, the on-line electrochemistry-ESI-MS experiments were performed using a wireless Bluetooth battery-powered instrument with the chip floating at the potential induced by the ESI high voltage. The described on-chip EC-ESI-MS device can be used for fundamental electrochemical investigations as well as for applications based on the use of electrochemically controlled sample pretreatment, preconcentration and ionisation steps prior to ESI-MS.

  12. pH-controlled dispersive liquid-liquid microextraction for the analysis of ionisable compounds in complex matrices: Case study of ochratoxin A in cereals.

    PubMed

    Campone, Luca; Piccinelli, Anna Lisa; Celano, Rita; Rastrelli, Luca

    2012-11-19

    A new sample preparation procedure, termed pH-controlled dispersive liquid-liquid microextraction (pH-DLLME), has been developed for the analysis of ionisable compounds in highly complex matrices. This DLLME mode, intended to improve the selectivity and to expand the application range of DLLME, is based on two successive DLLMEs conducted at opposite pH values. pH-DLLME was applied to determination of ochratoxin A (OTA) in cereals. The hydrophobic matrix interferences in the raw methanol extract (disperser, 1mL) were removed by a first DLLME (I DLLME) performed at pH 8 to reduce the solubility of OTA in the extractant (CCl(4), 400μL). The pH of the aqueous phase was then adjusted to 2, and the analyte was extracted and concentrated by a second DLLME (extractant, 150μL C(2)H(4)Br(2)). The main factors influencing the efficiency of pH-DLLME including type and volume of I DLLME extractant, as well as the parameters affecting the OTA extraction by II DLLME, were studied in detail. Under optimum conditions, the method has detection and quantification limits of 0.019 and 0.062μg kg(-1), respectively, with OTA recoveries in the range of 81.2-90.1% (n=3). The accuracy of the analytical procedure, evaluated with a reference material (cereal naturally contaminated with OTA), is acceptable (accuracy of 85.6%±1.7, n=5). The applicability of pH-DLLME to the selective extraction of other ionisable compounds, such as acidic and basic pharmaceutical products was also demonstrated. The additional advantages of pH-DLLME are a higher selectivity and the extension of this microextraction technique to highly complex matrices.

  13. Measurement of small ion beams by thermal ionisation mass spectrometry using new 10(13) Ohm resistors.

    PubMed

    Koornneef, J M; Bouman, C; Schwieters, J B; Davies, G R

    2014-03-28

    We tested 5 newly manufactured - prototype - 10(13)Ohm resistors in the feedback loop of Faraday cup amplifiers to measure small ion beams by Thermal Ionisation Mass Spectrometry (TIMS). The high Ohmic resistors installed in the TRITON Plus at the VU University Amsterdam theoretically have 10 times lower noise levels relative to the default 10(11)Ohm resistors. To investigate the precision and accuracy of analyses using these new amplifiers we measured Sr and Nd isotopes of reference standards at a range of ion currents (3.2×10(-16) to 1×10(-12) A, corresponding to intensities of 32 μV to 100 mV on a default 10(11)Ohm amplifier) and on small amounts of material (100 and 10 pg). Internal precision and external reproducibility for Sr and Nd isotope ratios are both better when collected on 10(13) compared 10(12)Ohm resistors and to the default 10(11)Ohm resistors. At an (87)Sr ion current of 3×10(-14) A (3 mV on a 10(11)Ohm amplifier) the internal precision (2 SE) of (87)Sr/(86)Sr is 5 times better for 10(13)Ohm resistors compared to 10(11)Ohm resistors. The external reproducibility (2 SD) at this beam intensity is 9 times better. Multiple 100 and 10 pg Sr standards, ran to exhaustion, yielded low (87)Sr/(86)Sr compared to the long term average (e.g. 10 pg average=0.710083±164 (n=11) instead of 0.710244±12, n=73). The average off-set for 10 pg standards can be explained by a loading blank contribution of 1.3 pg. In contrast, Nd data on 100 pg and 10 pg samples are accurate suggesting that Nd loading blanks do not compromise the data. The external reproducibility of (143)Nd/(144)Nd on 100 pg samples is 125 ppm and 3.3‰ on 10 pg samples (2 RSD=relative standard deviation, n=10). Thus, variability in Nd and Sr isotope ratios in the 4th decimal place, e.g. (143)Nd/(144)Nd 0.5110-0.5119 or (87)Sr/(86)Sr 0.7100-0.7109, can be resolved in 10 to 100 pg samples provided that the procedural blanks and chemical separation are optimal. For measurements in the beam

  14. Deoxyribonucleic acid damage-associated biomarkers of ionising radiation: current status and future relevance for radiology and radiotherapy

    PubMed Central

    Rothkamm, K

    2013-01-01

    Diagnostic and therapeutic radiation technology has developed dramatically in recent years, and its use has increased significantly, bringing clinical benefit. The use of diagnostic radiology has become widespread in modern society, particularly in paediatrics where the clinical benefit needs to be balanced with the risk of leukaemia and brain cancer increasing after exposure to low doses of radiation. With improving long-term survival rates of radiotherapy patients and the ever-increasing use of diagnostic and interventional radiology procedures, concern has risen over the long-term risks and side effects from such treatments. Biomarker development in radiology and radiotherapy has progressed significantly in recent years to investigate the effects of such use and optimise treatment. Recent biomarker development has focused on improving the limitations of established techniques by the use of automation, increasing sensitivity and developing novel biomarkers capable of quicker results. The effect of low-dose exposure (0–100 mGy) used in radiology, which is increasingly linked to cancer incidences, is being investigated, as some recent research challenges the linear-no-threshold model. Radiotherapy biomarkers are focused on identifying radiosensitive patients, determining the treatment-associated risk and allowing for a tailored and more successful treatment of cancer patients. For biomarkers in any of these areas to be successfully developed, stringent criteria must be applied in techniques and analysis of data to reduce variation among reports and allow data sets to be accurately compared. Newly developed biomarkers can then be used in combination with the established techniques to better understand and quantify the individual biological response to exposures associated with radiology tests and to personalise treatment plans for patients. PMID:23659923

  15. First field application of a thermal desorption resonance-enhanced multiphoton-ionisation single particle time-of-flight mass spectrometer for the on-line detection of particle-bound polycyclic aromatic hydrocarbons.

    PubMed

    Oster, Markus; Elsasser, Michael; Schnelle-Kreis, Jürgen; Zimmermann, Ralf

    2011-12-01

    The on-line analysis of single aerosol particles with mass spectrometrical methods is an important tool for the investigation of aerosols. Often, a single laser pulse is used for one-step laser desorption/ionisation of aerosol particles. Resulting ions are detected with time-of-flight mass spectrometry. With this method, the detection of inorganic compounds is possible. The detection of more fragile organic compounds and carbon clusters can be accomplished by separating the desorption and the ionisation in two steps, e.g. by using two laser pulses. A further method is, using a heated metal surface for thermal desorption of aerosol particles. If an ultraviolet laser is used for ionisation, a selective ionisation of polycyclic aromatic hydrocarbons (PAH) and alkylated PAH is possible via a resonance-enhanced multiphoton-ionisation process. Laser velocimetry allows individual laser triggering for single particles and additionally delivers information on aerodynamic particle diameters. It was shown that particles deriving from different combustion sources can be differentiated according to their PAH patterns. For example, retene, a C(4)-alkylated phenanthrene derivative, is a marker for the combustion of coniferous wood. In this paper, the first field application of a thermal desorption resonance-enhanced multiphoton-ionisation single particle time-of-flight mass spectrometer during a measurement campaign in Augsburg, Germany in winter 2010 is presented. Larger PAH-containing particles (i.e. with aerodynamic diameters larger than 1 μm), which are suspected to be originated by re-suspension processes of agglomerated material, were in the focus of the investigation. Due to the low concentration of these particles, an on-line virtual impactor enrichment system was used. The detection of particle-bound PAH in ambient particles in this larger size region was possible and in addition, retene could be detected on several particles, which allows to identify wood combustion as

  16. A miniaturised laser ablation/ionisation analyser for investigation of elemental/isotopic composition with the sub-ppm detection sensitivity

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

    2012-04-01

    Detailed knowledge of the elemental and isotopic composition of solar system objects imposes critical constraints on models describing the origin of our solar system and can provide insight to chemical and physical processes taking place during the planetary evolution. So far, the investigation of chemical composition of planetary surfaces could be conducted almost exclusively by remotely controlled spectroscopic instruments from orbiting spacecraft, landers or rovers. With some exceptions, the sensitivity of these techniques is, however, limited and often only abundant elements can be investigated. Nevertheless, the spectroscopic techniques proved to be successful for global chemical mapping of entire planetary objects such as the Moon, Mars and asteroids. A combined afford of the measurements from orbit, landers and rovers can also yield the determination of local mineralogy. New instruments including Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation/Ionisation Mass Spectrometer (LIMS), have been recently included for several landed missions. LIBS is thought to improve flexibility of the investigations and offers a well localised chemical probing from distances up to 10-13 m. Since LIMS is a mass spectrometric technique it allows for very sensitive measurements of elements and isotopes. We will demonstrate the results of the current performance tests obtained by application of a miniaturised laser ablation/ionisation mass spectrometer, a LIMS instrument, developed in Bern for the chemical analysis of solids. So far, the only LIMS instrument on a spacecraft is the LAZMA instrument. This spectrometer was a part of the payload for PHOBOS-GRUNT mission and is also currently selected for LUNA-RESURCE and LUNA-GLOB missions to the lunar south poles (Managadze et al., 2011). Our LIMS instrument has the dimensions of 120 x Ø60 mm and with a weight of about 1.5 kg (all electronics included), it is the lightest mass analyser designed for in situ chemical

  17. Second Cancers After Colorectal Cancer

    MedlinePlus

    ... After Colorectal Cancer Colorectal Cancer After Treatment Second Cancers After Colorectal Cancer Colorectal cancer survivors can be affected by a ... many of these cancers. Follow-up after colorectal cancer treatment After completing treatment for colorectal cancer, you ...

  18. Integrated Cancer Repository for Cancer Research

    ClinicalTrials.gov

    2017-05-05

    Pancreatic Cancer; Thyroid Cancer; Lung Cancer; Esophageal Cancer; Thymus Cancer; Colon Cancer; Rectal Cancer; GIST; Anal Cancer; Bile Duct Cancer; Duodenal Cancer; Gallbladder Cancer; Gastric Cancer; Liver Cancer; Small Intestine Cancer; Peritoneal Surface Malignancies; Familial Adenomatous Polyposis; Lynch Syndrome; Bladder Cancer; Kidney Cancer; Penile Cancer; Prostate Cancer; Testicular Cancer; Ureter Cancer; Urethral Cancer; Hypopharyngeal Cancer; Laryngeal Cancer; Lip Cancer; Oral Cavity Cancer; Nasopharyngeal Cancer; Oropharyngeal Cancer; Paranasal Sinus Cancer; Nasal Cavity Cancer; Salivary Gland Cancer; Skin Cancer; CNS Tumor; CNS Cancer; Mesothelioma; Breastcancer; Leukemia; Melanoma; Sarcoma; Unknown Primary Tumor; Multiple Myeloma; Ovarian Cancer; Endometrial Cancer; Vaginal Cancer

  19. Multi-residue analysis of drugs of abuse in wastewater and surface water by solid-phase extraction and liquid chromatography-positive electrospray ionisation tandem mass spectrometry.

    PubMed

    Baker, David R; Kasprzyk-Hordern, Barbara

    2011-03-25

    A new-multi residue method was developed for the environmental monitoring of 65 stimulants, opiod and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors, human urine indicators and their metabolites in wastewater and surface water. The proposed analytical methodology offers rapid analysis for a large number of compounds, with low limits of quantification and utilises only one solid-phase extraction-ultra performance liquid chromatography-positive electrospray ionisation tandem mass spectrometry (SPE-LC-MS/MS) method, thus overcoming the drawbacks of previously published procedures. The method employed solid phase extraction with the usage of Oasis MCX sorbent and subsequent ultra performance liquid chromatography-positive electrospray ionisation tandem mass spectrometry. The usage of a 1.7 μm particle size column (1 mm×150 mm) resulted in very low flow rates (0.04 mLmin(-1)), and as a consequence gave good sensitivity, low mobile phase consumption and short retention times for all compounds (from 2.9 to 23.1 min). High SPE recoveries (>60%) were obtained for the majority of compounds. The mean correlation coefficients of the calibration curves were typically higher than 0.997 and showed good linearity in the range 0-1000 μgL(-1). The method limits of detection ranged from 0.1 ngL(-1) for compounds including cocaine, benzoylecgonine, norbenzoylecgonine and 2-oxo-3-hydroxy-LSD to 100 ngL(-1) for caffeine. Method quantification limits ranged from 0.5 to 154.2 ngL(-1). Intra- and inter-day repeatabilities were on average less than 10%. The method accuracy range was within -33.1 to 30.1%. The new multi-residue method was used to analyse drugs of abuse in wastewater and river water in the UK environment. Of the targeted 65 compounds, 46 analytes were detected at levels above the method quantification limit (MQL) in wastewater treatment plant (WWTP) influent, 43 in WWTP effluent and 36 compounds in river water. Copyright

  20. Ionised silica in the estuary of a river as supply to seawater: Identification and ionization efficiency of silica species by FAB-MS

    NASA Astrophysics Data System (ADS)

    Tanaka, Miho; Takahashi, Kazuya

    2013-04-01

    Measurement of the dissolution state of silicic acid is difficult. In river water, silica exists in particle form, but silica particles with a diameter of less than approximately 0.45 μm are considered as dissolved silica. In seawater, silica exists in two forms: ionic silica and particle silica. In this study, we focused on ionic silica. Using fast atom bombardment mass spectrometry (FAB-MS), the silica species in river water and seawater were detected as ionic forms. Ionic silica forms various chemical species in aquatic solutions, including the monomer ([Si]) and dimer ([Si]). The relative abundances of these species in aquatic solutions depend on the chemical and physical conditions. Silica species such as [Si(OH)2O2Na]- ([monomer-Na+]-), [Si2(OH)5O2]- ([dimer]-), [Si2(OH)4O3Na]-([dimer-Na+]-), [Si4(OH)7O5]- ([cyclic tetramer]-), [Si4(OH)6O6Na]- ([cyclic tetramer-Na+]-), [Si4(OH)9O4]- ([linear tetramer]-) and [Si4(OH)8O5Na]- ([linear tetramer-Na+]-) were directly observed by FAB-MS in river water and seawater. Some of these ionic silica species are expected to serve as "nutrients" for diatoms in seawater. Large silica particles are transported in river water, whereas in estuaries, a large amount of silica is precipitated and a small amount of silica is dissolved as ionic forms in sodium chloride solution. In river water, the concentration of silica was high, but the ionic silica species were hardly ionised by FAB-MS. In seawater, the concentration of silica was low, but the ionic silica species were well ionised. Thus, the ionization efficiency of silica species by FAB-MS indicates the type of silica species. The filtration process of silicic acid and the ionization of silicic acid to dissolve the silica species in seawater, which is an electrolyte (sodium chloride), occur in the estuary of a river. Thus, the estuary of a river plays an important role in the restructuring of silica from particle form to ionic form.

  1. A new approach for plasma (xeno)metabolomics based on solid-phase extraction and nanoflow liquid chromatography-nanoelectrospray ionisation mass spectrometry.

    PubMed

    David, Arthur; Abdul-Sada, Alaa; Lange, Anke; Tyler, Charles R; Hill, Elizabeth M

    2014-10-24

    Current metabolite profiling methods based on liquid chromatography-mass spectrometry (LC-MS) platforms do not detect many of the components present at trace concentrations in extracts of plasma due to their low ionisation efficiency or to interference from highly abundant compounds. Nanoflow LC-nanospray MS platforms, which are commonly used in proteomics, could overcome these limitations and significantly increase analytical sensitivity and coverage of the plasma (xeno)metabolome (i.e., metabolites and xenobiotics), but require small injection volumes (<0.5μL). In this study, we developed sample preparation methods to remove ion suppressive phospholipids and concentrate remaining components of the plasma (xeno)metabolome in order to analyse sub-microliter volumes of plasma extracts for nanoflow ultra-high-performance liquid chromatography-nanoelectrospray ionisation-time-of-flight mass spectrometry (nUHPLC-nESI-TOFMS). These methods use phospholipid filtration plates in combination with polymeric or mixed mode exchange solid-phase extraction (SPE). The phospholipid filtration plates removed >94% of the predominant phospholipid/lysophospholipid species from plasma, whilst absolute recoveries of 63 selected (xeno)metabolites from spiked plasma were generally between 60 and 104%. After a further SPE step, recoveries of test compounds were between 50 and 81%. Studies revealed that both the sample preparation methodology and nUHPLC-nESI-TOFMS analyses gave acceptable repeatability. A qualitative comparison of SPE methods revealed that sample concentration by either polymer or mixed mode ion-exchange SPE gave comprehensive metabolite coverage of plasma extracts, but the use of cation exchange SPE significantly increased detection of many cationic compounds in the sample extracts. Method detection limits for steroid, eicosanoid and bile metabolites were <1.0ng/mL plasma and for pharmaceutical contaminants were between 0.01 and 30ng/mL plasma. Comparison of the

  2. A study of the analytical behaviour of selected synthetic and naturally occurring quinolines using electrospray ionisation ion trap mass spectrometry, liquid chromatography and gas chromatography and the construction of an appropriate database for quinoline characterisation.

    PubMed

    O'Donnell, F; Ramachandran, V N; Smyth, W F; Hack, C J; Patton, E

    2006-07-14

    Mass spectral fragmentation of quinoline alkaloids of significance in plants has been investigated using electrospray ionisation ion trap mass spectrometry (ESI-MS(n)) with a view to characterisation of molecules of unknown structure isolated from these natural sources. This investigation has led to the generation of an appropriate database incorporating data from ESI-MS(n) and also from gas liquid chromatography (GLC) and liquid chromatography (HPLC) for these low molecular mass quinolines. This has been put to practical application in the identification of quinoline alkaloids in a plant extract. Thus, an acid extraction of the leaves of Choisya ternata containing such tertiary alkaloids was analysed by liquid chromatography-electrospray ionisation mass spectrometry (HPLC-ESI-MS) and the resulting behaviour of the quinolines was compared with that of the quinoline alkaloids in the database.

  3. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

    NASA Astrophysics Data System (ADS)

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-02-01

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research.

  4. Comprehensive gas chromatography-electron ionisation mass spectrometric analysis of fatty acids and sterols using sequential one-pot silylation: quantification and isotopologue analysis.

    PubMed

    Kloos, Dick-Paul; Gay, Emmanuel; Lingeman, Henk; Bracher, Franz; Müller, Christoph; Mayboroda, Oleg A; Deelder, André M; Niessen, Wilfried M A; Giera, Martin

    2014-07-15

    Fatty acids and sterol lipids play crucial roles in several biological processes and several biological facts underline the interconnection between these lipid classes. Therefore, it is of interest to develop a comprehensive method analysing both classes in the form of their most favourable derivatives suitable for quantification and isotopologue analysis. Lipids were derivatised by a sequential one-pot procedure using N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MtBSTFA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). No clean-up or concentration steps were necessary. The prepared samples were directly available for gas chromatography-electron ionisation mass spectrometric (GC-EI-MS) analysis on a standard column. For quantification, the SIM mode was used and for isotopologue analysis scheduled scan mode was applied. Development of a sequential one-pot derivatisation for GC-EI-MS allowing comprehensive analysis of fatty acids and sterols as their most favourable derivatives. Validation carried out using human plasma, comparison with certified NIST plasma. LLOQ of usually 3.3 ng/mL achieved. Isotopologue analysis of 2-[(13)C]-acetate incorporation in HL-60 cells proving feasibility of method. The presented method successfully combines two consecutive silylation reactions in one pot, enabling the analysis of both fatty acids and sterols in a comprehensive analytical method. The method has great potential for the quantification of lipids as well as the comprehensive study of both biochemical pathways, using [(13)C]-flux analysis. Copyright © 2014 John Wiley & Sons, Ltd.

  5. Real-time analysis of organic compounds in ship engine aerosol emissions using resonance-enhanced multiphoton ionisation and proton transfer mass spectrometry.

    PubMed

    Radischat, Christian; Sippula, Olli; Stengel, Benjamin; Klingbeil, Sophie; Sklorz, Martin; Rabe, Rom; Streibel, Thorsten; Harndorf, Horst; Zimmermann, Ralf

    2015-08-01

    Organic combustion aerosols from a marine medium-speed diesel engine, capable to run on distillate (diesel fuel) and residual fuels (heavy fuel oil), were investigated under various operating conditions and engine parameters. The online chemical characterisation of the organic components was conducted using a resonance-enhanced multiphoton ionisation time-of-flight mass spectrometer (REMPI TOF MS) and a proton transfer reaction-quadrupole mass spectrometer (PTR-QMS). Oxygenated species, alkenes and aromatic hydrocarbons were characterised. Especially the aromatic hydrocarbons and their alkylated derivatives were very prominent in the exhaust of both fuels. Emission factors of known health-hazardous compounds (e.g. mono- and poly-aromatic hydrocarbons) were calculated and found in higher amounts for heavy fuel oil (HFO) at typical engine loadings. Lower engine loads lead in general to increasing emissions for both fuels for almost every compound, e.g. naphthalene emissions varied for diesel fuel exhaust between 0.7 mg/kWh (75 % engine load, late start of injection (SOI)) and 11.8 mg/kWh (10 % engine load, late SOI) and for HFO exhaust between 3.3 and 60.5 mg/kWh, respectively. Both used mass spectrometric techniques showed that they are particularly suitable methods for online monitoring of combustion compounds and very helpful for the characterisation of health-relevant substances. Graphical abstract Three-dimensional REMPI data of organic species in diesel fuel and heavy fuel oil exhaust.

  6. Structural elucidation of monoterpene oxidation products by ion trap fragmentation using on-line atmospheric pressure chemical ionisation mass spectrometry in the negative ion mode.

    PubMed

    Warscheid, B; Hoffmann, T

    2001-01-01

    Based on ion trap mass spectrometry, an on-line method is described which provides valuable information on the molecular composition of structurally complex organic aerosols. The investigated aerosols were generated from the gas-phase ozonolysis of various C(10)H(16)-terpenes (alpha-pinene, beta-pinene, 3-carene, sabinene, limonene), and directly introduced into the ion source of the mass spectrometer. Negative ion chemical ionisation at atmospheric pressure (APCI(-)) enabled the detection of multifunctional carboxylic acid products by combining inherent sensitivity and molecular weight information. Sequential low-energy collision-induced product ion fragmentation experiments (MS(n)) were performed in order to elucidate characteristic decomposition pathways of the compounds. Dicarboxylic acids, oxocarboxylic acids and hydroxyketocarboxylic acid products could be clearly distinguished by multistage on-line MS. Furthermore, sabinonic acid and two C(9)-ether compounds were tentatively identified for the first time by applying on-line APCI(-)-MS(n). Copyright 2001 John Wiley & Sons, Ltd.

  7. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

    PubMed Central

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-01-01

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research. PMID:28211480

  8. A liquid chromatography/electrospray ionisation tandem mass spectrometry method for the simultaneous quantification of salicylic, jasmonic and abscisic acids in Coffea arabica leaves.

    PubMed

    de Sá, Marta; Ferreira, João P; Queiroz, Vagner T; Vilas-Boas, Luís; Silva, Maria C; Almeida, Maria H; Guerra-Guimarães, Leonor; Bronze, Maria R

    2014-02-01

    Plants have developed an efficient system of recognition that induces a complex network of signalling molecules such as salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) in case of a pathogenic infection. The use of specific and sensitive methods is mandatory for the analysis of compounds in these complex samples. In this study a liquid chromatography/electrospray ionisation tandem mass spectrometry method was developed and validated for the simultaneous quantification of SA, JA and ABA in Coffea arabica (L.) leaves in order to understand the role of these phytohormones in the signalling network involved in the coffee defence response against Hemileia vastatrix. The results showed that the method was specific, linear (r ≥ 0.99) in the range 0.125-1.00 µg mL⁻¹ for JA and ABA and 0.125-5.00 µg mL⁻¹ for SA, and precise (relative standard deviation ≤11%), and the limit of detection (0.010 µg g⁻¹ fresh weight) was adequate for quantifying these phytohormones in this type of matrix. In comparison with healthy leaves, those infected with H. vastatrix (resistance reaction) displayed an increase in SA level 24 h after inoculation, suggesting the involvement of an SA-dependent pathway in coffee resistance. © 2013 Society of Chemical Industry.

  9. Examination of the translocation of sulfonylurea herbicides in sunflower plants by matrix-assisted laser desorption/ionisation mass spectrometry imaging.

    PubMed

    Anderson, David M G; Carolan, Vikki A; Crosland, Susan; Sharples, Kate R; Clench, Malcolm R

    2010-11-30

    Pesticides are widely used in agriculture to control weeds, pests and diseases. Successful control is dependent on the compound reaching the target site within the organism after spray or soil application. Conventional methods for determining uptake and movement of herbicides and pesticides include autoradiography, liquid scintillation and chromatographic techniques such as high-performance liquid chromatography (HPLC). Autoradiography using radiolabelled compounds provides the best indication of a compound's movement within the plant system. Autoradiography is an established technique but it relies on the synthesis of radiolabelled compounds. The distribution of four sulfonylurea herbicides in sunflower plants has been studied 24  h after foliar application. The use of matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) images of protonated molecules and fragment ions (resulting from fragmentation at the urea bond within the sulfonylurea herbicides) has provided evidence for translocation above and below the application point. The translocation of nicosulfuron and azoxystrobin within the same plant system has also been demonstrated following their application to the plant stem. This study provides evidence that MALDI-MSI has great potential as an analytical technique to detect and assess the foliar, root and stem uptake of agrochemicals, and to reveal their distribution through the plant once absorbed and translocated.

  10. Characterisation of chemical components for identifying historical Chinese textile dyes by ultra high performance liquid chromatography - photodiode array - electrospray ionisation mass spectrometer.

    PubMed

    Han, Jing; Wanrooij, Jantien; van Bommel, Maarten; Quye, Anita

    2017-01-06

    This research makes the first attempt to apply Ultra High Performance Liquid Chromatography (UHPLC) coupled to both Photodiode Array detection (PDA) and Electrospray Ionisation Mass Spectrometer (ESI-MS) to the chemical characterisation of common textile dyes in ancient China. Three different extraction methods, respectively involving dimethyl sulfoxide (DMSO)-oxalic acid, DMSO and hydrochloric acid, are unprecedentedly applied together to achieve an in-depth understanding of the chemical composition of these dyes. The first LC-PDA-MS database of the chemical composition of common dyes in ancient China has been established. The phenomena of esterification and isomerisation of the dye constituents of gallnut, gardenia and saffron, and the dye composition of acorn cup dyed silk are clarified for the first time. 6-Hydroxyrubiadin and its glycosides are first reported on a dyed sample with Rubia cordifolia from China. UHPLC-PDA-ESI-MS with a C18 BEH shield column shows significant advantages in the separation and identification of similar dye constituents, particularly in the cases of analysing pagoda bud and turmeric dyed sample extracts.

  11. Quantitative determination of methylphenidate in plasma by gas chromatography negative ion chemical ionisation mass spectrometry using o-(pentafluorobenzyloxycarbonyl)-benzoyl derivatives.

    PubMed

    Leis, Hans J; Schütz, Helmut; Windischhofer, Werner

    2011-06-01

    The use of a novel electrophoric derivatisation reagent, o-(pentafluorobenzyloxycarbonyl)-benzoyl chloride, for the quantitative determination of methylphenidate in plasma is described. The drug can be quantitatively measured down to 72 pg/mL plasma using only 250 μL of sample due to the extraordinary sensitivity of the derivatives under negative ion chemical ionisation mass spectrometry. Plasma samples were made alkaline with carbonate buffer and treated with extraction solvent n-hexane and reagent solution for 30 min, which, after concentration, was measured by GC-NICI-MS. The method is rapid as extraction and derivatisation occur in one single step. A stable isotope-labelled internal standard was used and its synthesis described. Full validation data are given to demonstrate the usefulness of the assay, including specificity, linearity, accuracy and precision, long-term stability, short-term stability, freeze-thaw stability, stock solution stability, autosampler stability, aliquot analysis, robustness, matrix effect, and prospective analytical batch size accuracy. The method has been successfully applied to pharmacokinetic profiling of the drug after oral application.

  12. Improvement in the Iatroscan thin-layer chromatographic-flame ionisation detection analysis of marine lipids. Separation and quantitation of monoacylglycerols and diacylglycerols in standards and natural samples.

    PubMed

    Striby, L; Lafont, R; Goutx, M

    1999-07-23

    Mono- and diacylglycerols are important intermediates in glycerolipid biodegradation and intracellular signalling pathways. A method for mass determination of these lipid classes in marine particles was developed using the Iatroscan, which combines thin layer chromatography (TLC) and flame ionisation detection (FID) techniques. We improved existing protocols by adding two elution steps: hexane-diethyl-ether-formic acid (70:30:0.2, v/v/v) after triacylglycerol and free fatty acid scan, and acetone 100% followed by chloroform-acetone-formic acid (99:1:0.2, v/v/v) after 1,2 diacylglycerols. Diacylglycerol isomers 1,2 and 1,3 were separated from each other, as well as from free sterols in standards and marine lipids from sediment trap particles. Monoacylglycerols were separated from pigments and galactosyl-lipids in the same trap samples and in a rich pigment phytoplankton extract of Dunaliella viridis. Quantitation of each class in samples was performed after calibration with 0.5 to 2 micrograms of standards. As many as 17 lipid classes can be identified and quantified in samples using this proposed six-step development.

  13. Rapid monitoring of carvacrol in plants and herbal medicines using matrix solid-phase dispersion and gas chromatography flame ionisation detector.

    PubMed

    Rashidipour, Marzieh; Heydari, Rouhollah; Feizbakhsh, Alireza; Hashemi, Payman

    2015-01-01

    Matrix solid-phase dispersion (MSPD) method coupled with gas chromatography flame ionisation detector as a quick and easy extraction technique has been developed to extract carvacrol from plants and herbal medicines. Influence of important parameters on the MSPD method efficiency, such as the sorbent material, the ratio of sample to sorbent material, elution solvent and volume of the elution solvent has been evaluated and optimised. Carvacrol was successfully extracted by diatomaceous earth as sorbent with 350 μL of dichloromethane as elution solvent. The calibration curve showed good linearity (r(2) = 0.9965) and precision (RSD < 8.16%) in the concentration range of 0.5-100 μg mL(-1) for carvacrol. The limit of detection and limit of quantification were 0.1 and 0.5 μg mL(-1), respectively. The recoveries were in the range of 74.4-80.5% with relative standard deviation (RSD) values ranging from 8.4% to 9.8%. The reported MSPD extraction method revealed to be simpler and faster than conventional methods used to quantify carvacrol from plants and herbal medicines.

  14. A predictive science approach to aid understanding of electrospray ionisation tandem mass spectrometric fragmentation pathways of small molecules using density functional calculations.

    PubMed

    Galezowska, Angelika; Harrison, Mark W; Herniman, Julie M; Skylaris, Chris-Kriton; Langley, G John

    2013-05-15

    Tandem mass spectrometry (MS/MS) dissociation pathways can vary markedly between compound classes and can result in challenging and time-consuming interpretation of the data. Compound, class and substructure specific fragmentation rules for protonated molecules require refinement to aid the structural elucidation process. The application of a predictive science approach using density functional theory (DFT) calculations has been investigated to estimate the abundances of first-generation product ions observed using an ion trap mass spectrometer. This has been achieved by application of Boltzmann population theory to electrospray ionisation (ESI)-MS and MS/MS data. Tandem ESI-MS data for this preliminary study were used to investigate the internal stabilities of protonated species and their product ions. The calculated relative abundances of 11.3%, 96.5%, and 1.1% for the product ion (m/z 192) of three quinazoline structural isomers are compared with the experimental values of 16%, 90% and 0% observed in the first-generation product ion mass spectra. Close correlation between calculated and experimental data has been demonstrated for these initial data. Applying this approach and establishing fragmentation rules, based on structure specific and common fragmentation behaviour, would improve and expedite the structural elucidation process. Copyright © 2013 John Wiley & Sons, Ltd.

  15. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

    NASA Astrophysics Data System (ADS)

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-02-01

    The ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. Nb{{\\text{O}}x} thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction.

  16. Evolution of the Observed Ly-alpha Luminosity Function from z = 6.5 to z = 7.7: Evidence for the Epoch of Re-ionisation?

    NASA Astrophysics Data System (ADS)

    Clément, B.; Cuby, J.-G.; Courbin, F.; Fontana, A.; Freudling, W.; Fynbo, J.; Gallego, J.; Hibon, P.; Kneib, J.-P.; Le Fèvre, O.; Lidman, C.; McMahon, R.; Milvang-Jensen, B.; Moller, P.; Nilsson, K. K.; Pentericci, L.; Venemans, B.; Villar, V.; Willis, J.

    2011-12-01

    Probing the first billion years of the Universe is one of the last frontiers in cosmology. Ly-alpha emitters (LAEs) are galaxies that can be detected out to very high redshifts during the epoch of re-ionisation. The evolution of their luminosity function with redshift is a direct probe of the Ly-alpha transmission of the intergalactic medium (IGM), related to the amount of neutral hydrogen. We report on the results of a search for LAEs at z = 7.7 using HAWK-I at the VLT with a narrowband filter centred at 1.06 μm. We did not find any LAE candidates, which allows us to infer robust constraints on the LAE luminosity function at z = 7.7. Depending on which luminosity functions at z = 6.5 are referred to, our results may reflect a significant quenching of the IGM Ly-alpha transmission, possibly from a strong increase in the neutral hydrogen fraction between these two redshifts.

  17. Simultaneous determination of monomethylmercury, monobutyltin, dibutyltin and tributyltin in environmental samples by multi-elemental-species-specific isotope dilution analysis using electron ionisation GC-MS.

    PubMed

    Moreno, Maria Jimenez; Pacheco-Arjona, Jaime; Rodríguez-González, Pablo; Preud'Homme, Hugues; Amouroux, David; Donard, Olivier F X

    2006-11-01

    In this work, the simultaneous determination of four organometallic species (monomethylmercury, monobutyltin, dibutyltin and tributyltin) in environmental samples by using a GC-MS system with electron ionisation has been established. The measurement of isotope ratios in each species was accomplished by selecting the most adequate molecular cluster, and simple mathematical equations were applied to correct the contributions of 13C from the organic groups attached to the tin and mercury atoms. The influence of different parameters such as dwell time on the precision and accuracy of the measured isotope ratios in each target species has also been studied. The determination and the sample preparation procedures presented in this work were first individually validated by analysing several certified reference materials for butyltin compounds (mussel tissue CRM-477 and marine sediment SOPH-1) and for monomethylmercury (tuna fish CRM-464) using an innovative focused microwave technology for the extraction of the species from the solid samples. Additionally, the simultaneous determination of the four species was successfully validated by obtaining quantitative recoveries in spiked natural waters and by analysing the certified reference material BCR-710 (certified in tributyltin and monomethylmercury). The values obtained in such certified tissue were fully in agreement not only with the certified mass fractions but also with the proposed indicative values for mono- and dibutyltin.

  18. Operation of low-noise single-gap RPC modules exposed to ionisation rates up to 1 kHz /cm2

    NASA Astrophysics Data System (ADS)

    Ćwiok, M.; Dominik, W.; Górski, M.; Królikowski, J.

    2004-11-01

    Two single gap medium-size RPC modules, made of bakelite plates of very good mechanical quality of the surface and having initial volume resistivity of 1 ×1010 Ω cm, were tested in the Gamma Irradiation Facility at CERN at ionisation rates up to 1 kHz /cm2. The internal surfaces facing the gas volume of one RPC module were cladded with a thin layer of linseed oil varnish for comparison of oiled and non-oiled RPC operation. The results refer to the gas mixture of C2H2F4/isobutane (97:3) with SF6 addition below 1%. The single gap modules exhibited full detection efficiency plateau for the high voltage range of about 1 kV at full intensity of gamma rays. Good timing characteristics allowed to reach 95% efficiency at fully opened irradiation source with time window of 20 ns. The intrinsic noise rate for a non-oiled and an oiled RPC gap was, respectively, below 5 and 1 Hz /cm2 at full efficiency over 1 kV voltage range.

  19. A preliminary investigation into a simple method for the determination of the mean ionisation energy of gas mixtures used in the NPL primary gas counting system.

    PubMed

    Phillips, H C; Sephton, J P; Johansson, L C; Dean, J C J

    2012-09-01

    The activity concentration of gaseous beta-emitting radionuclides such as (3)H, (85)Kr and, more recently, (11)C, is measured at NPL using a set of length-compensated proportional counters. The active gas is mixed with argon-methane (P-10) and passed to the counters. Adding gases to P-10 changes the mean ionisation energy, W, of the gas mixture. Estimation of the counting losses using the Monte Carlo model requires a knowledge of W. Unfortunately, only a limited amount of published data is available. This paper describes the initial experimental studies performed to enable the extension of the MC model based loss correction method to gases other than carbon dioxide in P-10. Preliminary measurements have been made to determine the W value for a gas mixture containing (85)Kr in nitrogen and P-10. The DC current through the counters is measured; the counters are also operated in the normal way with pulse amplifiers, discriminators and scalers. The value of W is derived from a knowledge of activity, counter current and mean beta energy.

  20. Matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry-based blood group genotyping--the alternative approach.

    PubMed

    Gassner, Christoph; Meyer, Stefan; Frey, Beat M; Vollmert, Caren

    2013-01-01

    Although matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF MS) has previously been reported for high throughput blood group genotyping, those reports are limited to only a few blood group systems. This review describes the development of a large cooperative Swiss-German project, aiming to employ MALDI-TOF MS for the molecular detection of the blood groups Rh, Kell, Kidd, Duffy, MNSs, a comprehensive collection of low incidence antigens, as well as the platelet and granulocyte antigens HPA and HNA, representing a total of 101 blood group antigens, encoded by 170 alleles, respectively. Recent reports describe MALDI-TOF MS as a technology with short time-to-resolution, ability for high throughput, and cost-efficiency when used in genetic analysis, including forensics, pharmacogenetics, oncology and hematology. Furthermore, Kell and RhD genotyping have been performed on fetal DNA from maternal plasma with excellent results. In summary, this article introduces a new technological approach for high throughput blood group genotyping by means of MALDI-TOF MS. Although all data presented are preliminary, the observed success rates, data quality and concordance with known blood group types are highly impressive, underlining the accuracy and reliability of this cost-efficient high throughput method. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Matrix-assisted laser desorption/ionisation mass spectrometry for the direct analysis of enzymatically digested kappa- iota- and hybrid iota/nu-carrageenans.

    PubMed

    Antonopoulos, Aristotelis; Hardouin, Julie; Favetta, Patrick; Helbert, William; Delmas, Agnès F; Lafosse, Michel

    2005-01-01

    Enzymatically digested oligosaccharides of kappa-, iota- and hybrid iota/nu-carrageenans were analysed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry in the negative-ion mode. nor-Harmane was used as matrix. Depending on the stock concentration and the laser intensity applied, the oligosaccharides exhibited losses of sulphate units (neutralised by the Na+ ion, and thus non-stable), leaving the primary backbone structure in most cases with only the deprotonated sulphate groups (carrying the negative charge, stable). This meant that kappa- and iota-oligosaccharides could not be easily distinguished from one another since they share the same primary backbone structure. However, for the hybrid iota/nu-oligosaccharides the primary backbone structure could be identified since the nu-carrageenan repeating unit differs from that of the kappa/iota-carrageenan unit. For all types of oligosaccharides, the results indicated cleavage of an anhydrogalactose unit from the non-reducing end. Specifically, for the hybrid oligosaccharides of iota/nu-carrageenans, this type of fragmentation means that the nu-carrageenan unit is not positioned on the non-reducing end of the hybrid oligosaccharides. Dehydration reactions, and exchange reactions of Na+ with K+ and Ca2+, were also observed. Copyright (c) 2005 John Wiley & Sons, Ltd.

  2. Induction of adaptive response: pre-exposure of mice to 900 MHz radiofrequency fields reduces hematopoietic damage caused by subsequent exposure to ionising radiation.

    PubMed

    Cao, Yi; Xu, Qian; Jin, Zong-Da; Zhou, Zhen; Nie, Ji-Hua; Tong, Jian

    2011-07-01

    To investigate whether an adaptive response can be induced in mice which were pre-exposed to 900 MHz radiofrequency fields. Adult male Kunming mice were exposed to 900 MHz radiofrequency fields (RF) at power intensities of 12, 120 and 1200 μW/cm(2) for 1 h/day for 14 days and then subjected to whole body gamma-irradiation. The results were compared with those in unexposed control animals and those exposed to gamma-irradiation alone (without pre-exposure to RF). The extent of survival and hematopoietic tissue damage (assessed in the form of nucleated colony forming cells in the bone marrow and colony forming cells in the spleen of lethally irradiated 'recipient' mice) as well as the expression of cell cycle-related genes were investigated. The results indicated a significant increase in survival time, reduction in the hematopoietic tissue damage in RF pre-exposed mice which were gamma-irradiated (as compared with those exposed to gamma-radiation alone). This was accompanied by significantly increased expression of cell cycle-related genes, namely, cyclin-D1, cyclin-E, cyclin-DK4 and cyclin-DK2 in hematopoietic cells. Pre-exposure of mice to 900 MHz radiofrequency fields has resulted in a significant reduction in hematopoietic damage caused by subsequent exposure to ionising radiation. This phenomenon appears to be similar to that of the 'adaptive response' which is well documented in scientific literature.

  3. Evaluation of hepatic clearance prediction using in vitro data: emphasis on fraction unbound in plasma and drug ionisation using a database of 107 drugs.

    PubMed

    Hallifax, David; Houston, J Brian

    2012-08-01

    Underprediction of in vivo intrinsic clearance (CL(int)) of unbound drug from human hepatic in vitro systems using physiological extrapolation methodology is accepted as a common outcome. Poulin et al. (2012. J Pharm Sci 101:838-851) recently proposed an approach involving determination of effective fraction unbound in plasma (fu(p)) based on albumin-facilitated hepatic uptake of acidic/neutral drugs which improved prediction accuracy and precision for 25 drugs highly bound to plasma proteins. This approach includes correction of unbound drug according to the ionisation fraction either side of the plasma membrane based on pH difference. Here, we assessed the proposed method using a larger database of predictions of CL(int) for 107 drugs involving hepatocytes (89 drugs) and microsomes (64 drugs). The proposed method was similarly effective in minimising average prediction bias (to within twofold), unlike the conventional fu(p) correction method. However, precision was similar between methods and there was no evidence in the larger database that prediction bias was associated with fu(p). Prediction bias for hepatocytes was clearance dependent by either method, indicating important sources of bias from in vitro methodology. Therefore, to progress beyond empirical correction of bias, there is further need of mechanistic elucidation to improve prediction methodology. Copyright © 2012 Wiley Periodicals, Inc.

  4. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbOx film growth

    DOE PAGES

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; ...

    2016-01-21

    Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B thanmore » in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbOx thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.« less

  5. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbOx film growth

    SciTech Connect

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-01-21

    Here, the ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +E x B than in -E x B direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. NbOx thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +E x B than in -E x B direction.

  6. Cancer - resources

    MedlinePlus

    Resources - cancer ... The following organizations are good resources for information on cancer : American Cancer Society -- www.cancer.org Cancer Care -- www.cancercare.org Cancer.Net -- www.cancer.net/coping- ...

  7. Cancer Basics

    MedlinePlus

    ... cancer is, how cancer is tracked, and the economic impact of cancer in the United States. Lifetime ... Cancer? Cancer Surveillance Programs in the United States Economic Impact of Cancer Finding Cancer Information Learn how ...

  8. A new approach to studying the effects of ionising radiation on single cells using FTIR synchrotron microspectroscopy

    NASA Astrophysics Data System (ADS)

    Lipiec, E.; Birarda, G.; Kowalska, J.; Lekki, J.; Vaccari, L.; Wiecheć, A.; Wood, B. R.; Kwiatek, W. M.

    2013-12-01

    The effect of ionizing radiation on single cells using a proton source was investigated using Fourier transform infrared (FTIR) microspectroscopy. The prostate cancer cells (DU-145) were irradiated by a specific number (50, 200, 400, 2000 and 4000) of protons per cell. Next after fixing the cells with 70% ethanol micro-FTIR spectra were obtained using both: (a) the synchrotron radiation source with a Mercury-Cadmium-Telluride (MCT) detector and (b) a globar source with a focal plane array (FPA) detector. FTIR spectra obtained from both instrumental configurations were analyzed independently to investigate the changes in the DNA phosphodiester region (1150-950 cm-1) of irradiated and control (untreated by ionizing radiation) cells. A Principal Component Analysis (PCA) scores plot revealed distinct clusters for all groups of irradiated cells, even for those irradiated by the smallest dose of protons. The dose-dependent changes in the relative intensities of DNA peak at 970 cm-1 (ribose-phosphate skeletal motions), along with a shift of the O-P-O band corresponding to the symmetric phosphodiester stretching mode at 1090 cm-1 were observed. The results demonstrate that FTIR spectroscopy is a promising tool to investigate DNA damage in single cells and may become an important tool in assessing cell damage following radiotherapy.

  9. Childhood and adult cancers: contrasts and commonalities.

    PubMed

    Murphy, Michael F G; Bithell, John F; Stiller, Charles A; Kendall, Gerald M; O'Neill, Kate A

    2013-09-01

    Tumours occurring in children differ considerably from those occurring at older ages but exhibit common features. Those occurring in the teenage/young adult (TYA) years represent a transitional mixture of child and adult tumours and pose a considerable challenge for optimal clinical management and service provision. Nevertheless the fundamental processes of malignant change, arising from genetic/epigenetic interaction with environmental exposures, seem to operate across all ages and the entire tumour spectrum. We focus here on the ways in which genotype (and epigenetic modification), growth processes (particularly in utero), and exposure to ionising radiation (in conjunction with genetic susceptibility) affect cancer risk from childhood to adulthood, whether as a primary occurrence, or a second primary tumour following earlier primary occurrence and treatment.

  10. Cancer of the testis, socioeconomic status, and occupation.

    PubMed Central

    Swerdlow, A J; Douglas, A J; Huttly, S R; Smith, P G

    1991-01-01

    The risk of testicular cancer in relation to lifetime histories of socioeconomic status, occupation, and occupational exposures was examined in a case-control study in England. Interviews were conducted with 259 cases, 238 control patients treated at radiotherapy and oncology centres, and 251 controls who were hospital inpatients in other departments. Risk of testicular cancer was raised in men of high socioeconomic status measured both by occupation and in other ways, and was similar in relation to status measured at birth and at various later stages of life. The occupations with highest risk of the tumour were paper and printing workers, professionals, and administrators. Exposures to various specific occupational agents that have been suggested in publications as potential risk factors were examined, but none showed an association with risk. The relative risk for occupational exposure to ionising radiation was 1.62 (95% confidence interval 0.83-3.17). PMID:1931725

  11. Mouse models for radiation-induced cancers.

    PubMed

    Rivina, Leena; Davoren, Michael J; Schiestl, Robert H

    2016-09-01

    Potential ionising radiation exposure scenarios are varied, but all bring risks beyond the simple issues of short-term survival. Whether accidentally exposed to a single, whole-body dose in an act of terrorism or purposefully exposed to fractionated doses as part of a therapeutic regimen, radiation exposure carries the consequence of elevated cancer risk. The long-term impact of both intentional and unintentional exposure could potentially be mitigated by treatments specifically developed to limit the mutations and precancerous replication that ensue in the wake of irradiation The development of such agents would undoubtedly require a substantial degree of in vitro testing, but in order to accurately recapitulate the complex process of radiation-induced carcinogenesis, well-understood animal models are necessary. Inbred strains of the laboratory mouse, Mus musculus, present the most logical choice due to the high number of molecular and physiological similarities they share with humans. Their small size, high rate of breeding and fully sequenced genome further increase its value for use in cancer research. This chapter will review relevant m. musculus inbred and F1 hybrid animals of radiation-induced myeloid leukemia, thymic lymphoma, breast and lung cancers. Method of cancer induction and associated molecular pathologies will also be described for each model. © The Author 2016. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. The effect of ionising radiation on testosterone binding globulin characteristics: correction of the protein' parameters by lipid polyene complexes of fungus Laetiporus sulfureus.

    PubMed

    Popoff, Eugene H; Kapich, Alexander N

    2010-03-01

    The aims of this work were: (i) To compare the effects of ionising radiation (IR) on testosterone binding globulin (TeBG) characteristics (serum concentration, cooperativity of androgen binding and affinity for hormone) in divergent mammalian species; (ii) to couple radiation effects with probable TeBG-parameter changes; and (iii) to investigate the prevention of these changes by fungal preparations (in particular - by lipid polyene complexes of Laetiporus sulphureus). Characteristics of TeBG were investigated in microaliquots of rat and human serum samples using [(3)H]-5 alpha-dihydrotestosterone ([(3)H]-DHT) radioligand assays after in vivo exposures to IR (external gamma-sources, incorporation of (131)I-, (137)Cs-radionuclides) at experimental and post-Chernobyl radioecological conditions (doses 0.25-2.2 Gy). Species-specific changes of TeBG parameters were found depending on the type of IR, dose and time after irradiation. Specifically children living in radionuclide contaminated regions (near Chernobyl) were found to have a decrease of positive cooperativity for the TeBG-androgen binding, a drop of TeBG levels, and a decline in hormone affinity. Screening of natural substances (from phanerogams and fungi) detected that lipid polyene complexes of the basidiomycete L. sulphureus allowed recovery of the standard features of TeBG. IR induced a depletion of TeBG from blood simultaneously with species-specific changes of TeBG, which depend on the type of radiation, the dose of radiation (from 0.25 up to 2.2 Gy), and the time after radiation. The Hill coefficient of TeBG (indicating the degree of molecular cooperativity when hormone binding) appeared to be the most radiosensitive marker of the glycoprotein activity because of it is inversely to radiation dose. There are pharmacological possibilities to restore IR-induced "declines" of TeBG's affinity and cooperativity for androgen ligand binding.

  13. The effects of three bioreductive drugs (mitomycin C, RSU-1069 and SR4233) on cell lines selected for their sensitivity to mitomycin C or ionising radiation.

    PubMed

    Keohane, A; Godden, J; Stratford, I J; Adams, G E

    1990-05-01

    We have investigated the cross-sensitivity of a number of cell lines to three different classes of bioreductive drugs under both aerobic and hypoxic conditions. The cell lines used were selected for their sensitivity to DNA-damaging agents and fall into two groups. One group, MMC cells derived from CHO-K1 cells (Robson et al., 1985), show a range of sensitivities to mitomycin C in air. The second group, irs cells were cloned from V79 Chinese hamster fibroblasts (Jones et al., 1987) and exhibit sensitivity to ionising radiation. The sensitivity of both groups of cells to mitomycin C (MMC), RSU-1069 and SR4233 was assessed under aerobic and hypoxic conditions. No difference in aerobic or hypoxic toxicity of MMC was observed for CHO-K1 or MMC sensitive cell lines (MMC-2 and MMC-3). However, the MMC-resistant cell line (MMCr) was 10 times more sensitive under hypoxic than aerobic conditions. This suggests that MMCr cells lack or are deficient in the enzymes responsible for activating MMC under aerobic conditions compared to other MMC cells. In contrast, differential toxicities of between 3 and 30 have been observed for all CHO cells treated with RSU-1069 and SR4233. Treatment of V79 and irs cells with RSU-1069 and SR4233 also resulted in selective toxicity towards hypoxic cells. Differential toxicities between 50 and 100 were observed for V79 cells. For both RSU-1069 and SR4233, the hypoxic toxicities were similar in V79 and irs cells but in air, the radiation sensitive cells were up to 10 times more sensitive than wild type cells.

  14. The effects of three bioreductive drugs (mitomycin C, RSU-1069 and SR4233) on cell lines selected for their sensitivity to mitomycin C or ionising radiation.

    PubMed Central

    Keohane, A.; Godden, J.; Stratford, I. J.; Adams, G. E.

    1990-01-01

    We have investigated the cross-sensitivity of a number of cell lines to three different classes of bioreductive drugs under both aerobic and hypoxic conditions. The cell lines used were selected for their sensitivity to DNA-damaging agents and fall into two groups. One group, MMC cells derived from CHO-K1 cells (Robson et al., 1985), show a range of sensitivities to mitomycin C in air. The second group, irs cells were cloned from V79 Chinese hamster fibroblasts (Jones et al., 1987) and exhibit sensitivity to ionising radiation. The sensitivity of both groups of cells to mitomycin C (MMC), RSU-1069 and SR4233 was assessed under aerobic and hypoxic conditions. No difference in aerobic or hypoxic toxicity of MMC was observed for CHO-K1 or MMC sensitive cell lines (MMC-2 and MMC-3). However, the MMC-resistant cell line (MMCr) was 10 times more sensitive under hypoxic than aerobic conditions. This suggests that MMCr cells lack or are deficient in the enzymes responsible for activating MMC under aerobic conditions compared to other MMC cells. In contrast, differential toxicities of between 3 and 30 have been observed for all CHO cells treated with RSU-1069 and SR4233. Treatment of V79 and irs cells with RSU-1069 and SR4233 also resulted in selective toxicity towards hypoxic cells. Differential toxicities between 50 and 100 were observed for V79 cells. For both RSU-1069 and SR4233, the hypoxic toxicities were similar in V79 and irs cells but in air, the radiation sensitive cells were up to 10 times more sensitive than wild type cells. PMID:2110815

  15. Direct Identification of Bacteria in Positive Blood Culture Bottles by Matrix-Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry

    PubMed Central

    La Scola, Bernard; Raoult, Didier

    2009-01-01

    Background With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. Methodology/Principal Findings We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66%) were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. Conclusions/Significance MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture broths growing viridans

  16. A dynamic system for the simulation of fasting luminal pH-gradients using hydrogen carbonate buffers for dissolution testing of ionisable compounds.

    PubMed

    Garbacz, Grzegorz; Kołodziej, Bartosz; Koziolek, Mirko; Weitschies, Werner; Klein, Sandra

    2014-01-23

    The hydrogen carbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions and covers the physiological pH range of the luminal fluids from pH 5.5 to about pH 8.4. The pH value of a hydrogen carbonate buffer is the result of a complex and dynamic interplay of the concentration of hydrogen carbonate ions, carbonic acid, the concentration of dissolved and solvated carbon dioxide and its partial pressure above the solution. The complex equilibrium between the different ions results in a thermodynamic instability of hydrogen carbonate solutions. In order to use hydrogen carbonate buffers with pH gradients in the physiological range and with the dynamics observed in vivo without changing the ionic strength of the solution, we developed a device (pHysio-grad®) that provides both acidification of the dissolution medium by microcomputer controlled carbon dioxide influx and alkalisation by degassing. This enables a continuous pH control and adjustment during dissolution of ionisable compounds. The results of the pH adjustment indicate that the system can compensate even rapid pH changes after addition of a basic or acidic moiety in amounts corresponding up to 90% of the overall buffer capacity. The results of the dissolution tests performed for a model formulation containing ionizable compounds (Nexium 20mg mups) indicate that both the simulated fasting intraluminal pH-profiles and the buffer species can significantly affect the dissolution process by changing the lag time prior to initial drug release and the release rate of the model compound. A prediction of the in vivo release behaviour of this formulation is thus most likely strongly related to the test conditions such as pH and buffer species. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.

    PubMed

    Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

    2014-05-01

    The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (<2 %) and human errors (<1 %) suggested that the system was sufficiently robust to be implemented in a network. With a median time-to-identification of 5 h and 11 min (78 min, min-max: 154-547), MALDI-TOF MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p < 0.0001). However, the limited clinical benefits of the chromogenic culture media do not support their extra cost. Our financial analysis also suggested that MALDI-TOF MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems.

  18. The Spatial Distribution of Alkaloids in Psychotria prunifolia (Kunth) Steyerm and Palicourea coriacea (Cham.) K. Schum Leaves Analysed by Desorption Electrospray Ionisation Mass Spectrometry Imaging.

    PubMed

    Kato, Lucilia; Moraes, Aline Pereira; de Oliveira, Cecília Maria Alves; Vaz, Boniek Gontijo; de Almeida Gonçalves, Letícia; E Silva, Elienai Cândida; Janfelt, Christian

    2017-09-06

    Species of the genera Psychotria and Palicourea are sources of indole alkaloids, however, the distribution of alkaloids within the plants is not known. Analysing the spatial distribution using desorption electrospray ionisation mass spectrometry imaging (DESI-MSI) has become attractive due to its simplicity and high selectivity compared to traditional histochemical techniques. To apply DESI-MSI to visualise the alkaloid distribution on the leaf surface of Psychotria prunifolia and Palicourea coriacea and to compare the distributions with HPLC-MS and histochemical analyses. Based upon previous structure elucidation studies, four alkaloids targeted in this study were identified using high resolution mass spectrometry by direct infusion of plant extracts, and their distributions were imaged by DESI-MSI via tissue imprints on a porous Teflon surface. Relative quantitation of the four alkaloids was obtained by HPLC-MS/MS analysis performed using multiple-reaction monitoring (MRM) mode on a triple quadrupole mass spectrometer. Alkaloids showed distinct distributions on the leaf surfaces. Prunifoleine was mainly present in the midrib, while 10-hydroxyisodeppeaninol was concentrated close to the petiole; a uniform distribution of 10-hydroxyantirhine was observed in the whole leaf of Psychotria prunifolia. The imprinted image from the Palicourea coriacea leaf also showed a homogeneous distribution of calycanthine throughout the leaf surface. Different distributions were found for three alkaloids in Psychotria prunifolia, and the distributions found by MSI were in complete accordance with HPLC-MS analysis and histochemical results. The DESI-MSI technique was therefore demonstrated to provide reliable information about the spatial distribution of metabolites in plants. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Heat effects on DNA repair after ionising radiation: hyperthermia commonly increases the number of non-repaired double-strand breaks and structural rearrangements

    PubMed Central

    El-Awady, R. A.; Dikomey, E.; Dahm-Daphi, J.

    2001-01-01

    After ionising radiation double-strand breaks (dsb) are lethal if not repaired or misrepaired. Cell killing is greatly enhanced by hyperthermia and it is questioned here whether heat not only affects dsb repair capacity but also fidelity in a chromosomal context. dsb repair experiments were designed so as to mainly score non-homologous end joining, while homologous recombination was largely precluded. Human male G0 fibroblasts were either preheated (45°C, 20 min) or not before X-irradiation. dsb induction and repair were measured by conventional gel electrophoresis and an assay combining restriction digestion using a rare cutting enzyme (NotI) and Southern hybridisation, which detects large chromosomal rearrangements (>100 kb). dsb induction rate in an X-chromosomal NotI fragment was 4.8 × 10–3 dsb/Gy/Mb. Similar values were found for the genome overall and also when cells were preheated. After 50 Gy, fibroblasts were competent to largely restore the original restriction fragment size. Five per cent of dsb remained non-rejoined and 14% were misrejoined. Correct restitution of restriction fragments occurred preferably during the first hour but continued at a slow rate for 12–16 h. In addition, dsb appeared to misrejoin throughout the entire repair period. After hyperthermia the fractions of non-rejoined and misrejoined dsb were similarly increased to 13 and 51%, respectively. It is suggested that heat increases the probability of dsb being incorrectly rejoined but it is not likely to interfere with one dsb repair pathway in particular. PMID:11328880

  20. Introduction, audit and review of guidelines for delegated authorization of nuclear medicine investigations in compliance with the Ionising Radiation (Medical Exposure) Regulations 2000.

    PubMed

    Harris, A M; Greaves, C D; Taylor, C M; Taylor, C; Segasby, C A; Tindale, W B

    2003-08-01

    The introduction of the Ionising Radiation (Medical Exposure) Regulations 2000 in Great Britain required every nuclear medicine investigation to be justified by a practitioner holding an appropriate Administration of Radioactive Substances Committee (ARSAC) certificate. The task of authorizing the radiation exposure may be performed by the practitioner (direct authorization) or delegated to an appropriately trained operator working to written guidelines approved by the practitioner (delegated authorization). In this study, we look at the process of implementation, audit and review of a set of Delegated Authorization Guidelines (DAG). The process of drafting the DAG is outlined. Following the introduction of the DAG, an audit of nuclear medicine referrals was performed at two sites for a period of 3 months. Each referral was compared with the DAG to determine whether it matched the criteria set out. If it did not match, it was further categorized as being due to: (1) insufficient referral information; or (2) clinical indication not included in the DAG. All non-matching requests were reviewed by the practitioner. Four hundred and thirty-seven of 632 (69%) referrals fitted the DAG, 12% (n=75) required clarification from the referrer before fitting with the criteria and 19% (n=120) were directly authorized by the practitioner. From those referrals that were directly authorized, some additional indications were identified and the DAG were subsequently revised. In conclusion, a delegated authorization procedure for nuclear medicine investigations can be implemented successfully. Regular audit is essential. This study identified the need to improve the format of the request card and to obtain additional referral information from the referrer.

  1. General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri.

    PubMed

    Escher, Beate I; Baumer, Andreas; Bittermann, Kai; Henneberger, Luise; König, Maria; Kühnert, Christin; Klüver, Nils

    2017-03-22

    The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

  2. InterCardioRisk: a novel online tool for estimating doses of ionising radiation to occupationally-exposed medical staff and their associated health risks.

    PubMed

    Moriña, David; Grellier, James; Carnicer, Adela; Pernot, Eileen; Ryckx, Nick; Cardis, Elisabeth

    2016-09-01

    Those working in interventional cardiology and related medical procedures are potentially subject to considerable exposure to x-rays. Two types of tissue of particular concern that may receive considerable doses during such procedures are the lens of the eye and the brain. Ocular radiation exposure results in lens changes that, with time, may progress to partial or total lens opacification (cataracts). In the early stages, such opacities do not result in visual disability; the severity of such changes tends to increase progressively with dose and time until vision is impaired and cataract surgery is required. Scattered radiation doses to the eye lens of an interventional cardiologist in typical working conditions can exceed 34 μGy min(-1) in high-dose fluoroscopy modes and 3 μGy per image during image acquisition (instantaneous rate values) when radiation protection tools are not used. A causal relation between exposure to ionising radiation and increased risk of brain and central nervous system tumours has been shown in a number of studies. Although absorbed doses to the brain in interventional cardiology procedures are lower than those to the eye lens by a factor between 3.40 and 8.08 according to our simulations, doses to both tissues are among the highest occupational radiation doses documented for medical staff whose work involves exposures to x-rays. We present InterCardioRisk, a tool featuring an easy-to-use web interface that provides a general estimation of both cumulated absorbed doses experienced by medical staff exposed in the interventional cardiology setting and their estimated associated health risks. The tool is available at http://intercardiorisk.creal.cat.

  3. Determination of cholesterol oxides in processed food using high-performance liquid chromatography-mass spectrometry with atmospheric pressure chemical ionisation.

    PubMed

    Razzazi-Fazeli, E; Kleineisen, S; Luf, W

    2000-10-27

    The present work describes the development and application of an on-line atmospheric pressure ionisation (APCI) LC-MS interface for the simultaneous determination of seven toxicologically relevant cholesterol oxides (7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, 25-hydroxycholesterol, 7-ketocholesterol, 5,6alpha-, 5,6beta-epoxycholesterol and cholestan-3beta,5alpha,6beta-triol). The HPLC method has been optimised to reach better separation of all tested compounds. The influences of APCI parameters (nebulising temperature, cone voltage, source temperature) on signal intensity and fragmentation pattern were investigated for all tested cholesterol oxides compounds. This is the first report on optimisation and determination of two compounds 7alpha-hydroxycholesterol and 5,6beta-epoxycholesterol in processed food using LC-MS. After extraction with hexane, clean-up was carried out using solid-phase extraction on a silica column. For the chromatographic separation of cholesterol oxides an Aquasil C18 column was used with acetonitrile-methanol (60:40) as mobile phase. For the first time we report the use of such a C18 column with a relatively hydrophilic nature for the separation of cholesterol oxides. APCI-MS detection was then applied in selected ion monitoring and positive ion modes by using the molecular ions and the main fragments. The developed method shows good linearity, high repeatability and good recovery for all tested cholesterol oxides. The method was applied for determination of seven selected cholesterol oxidation products in different foodstuffs such as butter, butteroil, lard and egg powder.

  4. A quick and easy method to identify bacteria by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

    PubMed

    Pennanec, Xaviera; Dufour, Alain; Haras, Dominique; Réhel, Karine

    2010-02-01

    Concerns with water quality have increased in recent years, in part due to the more frequent contamination of water by pathogens like E. coli and L. pneumophila. Current methods for the typing of bacteria in water samples are based on culture of samples on specific media. These techniques are time-consuming, subject to the impact of interferents and do not totally meet all the requirements of prevention. There is a need for accurate and rapid identification of these microorganisms. This report deals with the detection of bacteria, more precisely of Legionella spp., and the development of an analytical strategy for a rapid and unambiguous identification of these pathogens in water from diverse origins. Therefore, a protein mass mapping using matrix-assisted laser desorption/ionisation mass spectrometry (MALDI MS) of whole bacteria combined with a home-made database of bacteria spectra is applied. A large variety of different bacteria and microorganisms is used to approach the actual composition of samples with numerous interferents. The objective is to propose a universal method for sampling preparation before MALDI MS analysis and optimised spectrometric conditions for reproducible intense peaks. Several experimental factors known to influence signal quality such as time and media of culture have been studied. The proposed method gives promising results for a sure differentiation of Legionella species and subspecies and a rapid identification of bacteria which are the most dangerous or difficult to eradicate. This method is easy to perform with an excellent reproducibility. The analytical protocol and the corresponding database were validated on samples from different origins (cooling tower, plumbing hot water). Copyright 2010 John Wiley & Sons, Ltd.

  5. The assessment of ionising radiation impact on the cooling pond freshwater ecosystem non-human biota from the Ignalina NPP operation beginning to shut down and initial decommissioning.

    PubMed

    Mazeika, J; Marciulioniene, D; Nedveckaite, T; Jefanova, O

    2016-01-01

    The radiological doses to non-human biota of freshwater ecosystem in the Ignalina NPP cooling pond - Lake Druksiai were evaluated for several cases including the plant's operation period and initial decommissioning activities, using the ERICA 1.2 code with IAEA SRS-19 models integrated approach and tool. Among the Lake Druksiai freshwater ecosystem reference organisms investigated the highest exposure dose rate was determined for bottom fauna - benthic organisms (mollusc-bivalves, crustaceans, mollusc-gastropods, insect larvae), and among the other reference organisms - for vascular plants. The mean and maximum total dose rate values due to anthropogenic radionuclide ionising radiation impact in all investigated cases were lower than the ERICA screening dose rate value of 10 μGy/h. The main exposure of reference organisms as a result of Ignalina NPP former effluent to Lake Druksiai is due to ionizing radiation of radionuclides (60)Co and (137)Cs, of predicted releases to Lake Druksiai during initial decommissioning period - due to radionuclides (60)Co, (134)Cs and (137)Cs, and as a result of predicted releases to Lake Druksiai from low- and intermediate-level short-lived radioactive waste disposal site in 30-100 year period - due to radionuclides (99)Tc and (3)H. The risk quotient expected values in all investigated cases were <1, and therefore the risk to non-human biota can be considered negligible with the exception of a conservative risk quotient for insect larvae. Radiological protection of non-human biota in Lake Druksiai, the Ignalina NPP cooling pond, is both feasible and acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Direct identification of bacteria in positive blood culture bottles by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.

    PubMed

    La Scola, Bernard; Raoult, Didier

    2009-11-25

    With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66%) were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture broths growing viridans streptococci is obtained in the near future.

  7. Investigation of pyrrolizidine alkaloids including their respective N-oxides in selected food products available in Hong Kong by liquid chromatography electrospray ionisation mass spectrometry.

    PubMed

    Chung, Stephen W C; Lam, Aaron C H

    2017-07-01

    This study determined the levels of pyrrolizidine alkaloids (PAs), including their respective N-oxides, in foodstuffs available in Hong Kong by liquid chromatography-electrospray ionisation tandem mass spectrometry. A total of 234 samples (48 food items) were collected randomly from a local market and analysed. About 50% of samples were found to contain detectable amount of PAs. Amongst the 48 food items, PAs were not detected in 11 food items, including barley flour, beef, cattle liver, pork, pig liver, chicken meat, chicken liver, milk, non-fermented tea, Melissa tea and linden tea. For those found to contain detectable PAs, the summed PA content ranged up to 11,000 µg kg(-1). The highest sum of PA content among the 37 food items calculated with lower bound was cumin seed, then followed by oregano, tarragon and herbs de Provence with ranges of 2.5-11,000, 1.5-5100, 8.0-3300 and 18-1300 µg kg(-1) respectively. Among the samples, the highest sum of PA content was detected in a cumin seed sample (11,000 µg kg(-1)), followed by an oregano (5100 µg kg(-1)), a tarragon (3300 µg kg(-1)) and a herbs de Provence (1300 µg kg(-1)). In general, the results of this study agreed well with other published results in peer-reviewed journals, except that the total PAs in honey and specific tea infusion in this study were comparatively lower.

  8. Rapid identification of additives in poly(vinyl chloride) lid gaskets by direct analysis in real time ionisation and single-quadrupole mass spectrometry.

    PubMed

    Rothenbacher, Thorsten; Schwack, Wolfgang

    2010-01-01

    Gaskets for lids of glass jars usually consist of poly(vinyl chloride) (PVC) containing plasticisers and additional additives, which may migrate into packed foodstuffs. To conform to legal regulations, any such migration has to be determined analytically, which is a big challenge due to the huge chemical variety of additives in use. Therefore, a rapid screening method by means of direct analysis in real time mass spectrometry (DART-MS), using a single-quadrupole mass spectrometer, was developed. On introducing a plastisol sample into the DART interface, protonated molecules and ammonium adducts were obtained as the typical ionisation products of any additives present, and cleavages of ester bonds as typical fragmentation processes. Generally, additives present in the 1% range could be directly and easily identified if ion suppressive effects deriving from specific molecules did not occur. These effects could be avoided by analysing toluene extracts of plastisol samples, and this also improved the sensitivity. Using this method, it was possible to identify phthalates, fatty acid amides, tributyl O-acetylcitrate, dibutyl sebacate, bis(2-ethylhexyl) adipate, 1,2-diisononyl 1,2-cyclohexanedicarboxylate, and even more complex additives like acetylated mono- and diacylglycerides, epoxidised soybean oil, and polyadipates, with a limit of detection of < or = 1% in PVC plastisols. Only in the case of epoxidised linseed oil were levels of > or = 5% required for identification. The detection of azodicarbonamide, used as a foaming agent within the manufacturing process, was possible in principle, but was not highly reproducible due to the very low concentrations in plastisols.

  9. On-line measurements of α-pinene ozonolysis products using an atmospheric pressure chemical ionisation ion-trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Warscheid, Bettina; Hoffmann, Thorsten

    An on-line technique to investigate complex organic oxidation reactions in environmental chamber experiments is presented. The method is based on the direct introduction of the chamber air into an atmospheric pressure ion source of a commercial ion-trap mass spectrometer. To demonstrate the analytical potential of the method (atmospheric pressure chemical ionisation/mass spectrometry, APCI/MS), the ozonolysis of α-pinene was investigated in a series of experiments performed in various sized reaction chambers at atmospheric pressure and 296 K in synthetic air. Investigations were focussed on the influence of the water vapour concentration on the formation of the predominant oxidation product, pinonaldehyde, derived from the α-pinene/ozone reaction. Quantification of pinonaldehyde was achieved by conducting a standard addition technique. The molar yield of pinonaldehyde was found to depend strongly on the actual water vapour concentration between <1 and 80% relative humidity. Starting with an average yield of 0.23±0.05 at dry conditions, pinonaldehyde formation was approximately doubled by reaching a yield of 0.53±0.05 at a relative humidity of around 60%. Furthermore, the formation mechanism of pinonaldehyde was investigated in greater detail using isotopically labelled water. Applying on-line APCI/MS, pinonaldehyde formation under incorporation of 18O was observed, strongly supporting the reaction of the stabilised Criegee radical with water in the gas phase as suggested by Alvarado et al. (Journal of Geophysical Research 103 (1998) 25541-25551). Furthermore, the mass spectra recorded on-line were used to perform a semi-quantitative estimation of the decomposition pathway of the primary ozonide, indicating a branching ratio of 0.35/0.65.

  10. Eye Cancer

    MedlinePlus

    ... Cancer > Eye Cancer > Eye Cancer: Overview Request Permissions Eye Cancer: Overview Approved by the Cancer.Net Editorial ... trained to treat intraocular cancer. Parts of the eye The eye is the organ that collects light ...

  11. Vulva cancer

    MedlinePlus

    ... Cancer - perineum; Cancer - vulvar; Genital warts - vulvar cancer; HPV - vulvar cancer ... is rare. Risk factors include: Human papilloma virus (HPV, or genital warts ) infection in women under age ...

  12. Comprehensive chemical comparison of fuel composition and aerosol particles emitted from a ship diesel engine by gas chromatography atmospheric pressure chemical ionisation ultra-high resolution mass spectrometry with improved data processing routines.

    PubMed

    Rüger, Christopher P; Schwemer, Theo; Sklorz, Martin; O'Connor, Peter B; Barrow, Mark P; Zimmermann, Ralf

    2017-02-01

    The analysis of petrochemical materials and particulate matter originating from combustion sources remains a challenging task for instrumental analytical techniques. A detailed chemical characterisation is essential for addressing health and environmental effects. Sophisticated instrumentation, such as mass spectrometry coupled with chromatographic separation, is capable of a comprehensive characterisation, but needs advanced data processing methods. In this study, we present an improved data processing routine for the mass chromatogram obtained from gas chromatography hyphenated to atmospheric pressure chemical ionisation and ultra high resolution mass spectrometry. The focus of the investigation was the primary combustion aerosol samples, i.e. particulate matter extracts, as well as the corresponding fossil fuels fed to the engine. We demonstrate that utilisation of the entire transient and chromatographic information results in advantages including minimisation of ionisation artefacts and a reliable peak assignment. A comprehensive comparison of the aerosol and the feed fuel was performed by applying intensity weighted average values, compound class distribution and principle component analysis. Certain differences between the aerosol generated with the two feed fuels, diesel fuel and heavy fuel oil, as well as between the aerosol and the feed were revealed. For the aerosol from heavy fuel oil, oxidised species from the CHN and CHS class precursors of the feed were predominant, whereas the CHOx class is predominant in the combustion aerosol from light fuel oil. Furthermore, the complexity of the aerosol increases significantly compared to the feed and incorporating a higher chemical space. Coupling of atmospheric pressure chemical ionisation to gas chromatography was found to be a useful additional approach for characterisation of a combustion aerosol, especially with an automated utilisation of the information from the ultra-high resolution mass spectrometer

  13. Efficacy of point-of-entry copper--silver ionisation system in eradicating Legionella pneumophila in a tropical tertiary care hospital: implications for hospitals contaminated with Legionella in both hot and cold water.

    PubMed

    Chen, Y S; Lin, Y E; Liu, Y-C; Huang, W K; Shih, H Y; Wann, S R; Lee, S S; Tsai, H C; Li, C H; Chao, H L; Ke, C M; Lu, H H; Chang, C L

    2008-02-01

    A medical centre in Southern Taiwan experienced an outbreak of nosocomial Legionnaires' disease, with the water distribution system thought to be the source of the infection. Even after two superheats and flush, the rate of Legionella positivity in distal sites in hospital wards and intensive care units (ICUs) was 14% and 66%, respectively. Copper-silver ionisation was therefore implemented in an attempt to control Legionella colonisation in both hot- and cold-water systems. Environmental cultures and ion concentration testing were performed to evaluate the efficacy of ionisation. When the system was activated, no significant change in rate of Legionella positivity in the hospital wards (20% vs baseline of 30%) and ICUs (28% vs baseline of 34%) of the test buildings over a three-month period was found, although all Legionella positivity rates were below 30%, an arbitrary target for Legionnaires' disease prevention. When ion concentrations were increased from month 4 to month 7, however, the rate of Legionella positivity decreased significantly to 5% (mean) in hospital wards (P=0.037) and 16% (mean) in ICUs (P=0.037). Legionella positivity was further reduced to 0% in hospital wards and 5% (mean) in ICUs while 50% sites were still positive for Legionella in a control building. Although Legionella was not completely eradicated during the study period, no culture- or urine-confirmed hospital-acquired Legionnaires' disease was reported. Ionisation was effective in controlling Legionella for both hot and cold water, and may be an attractive alternative as a point-of-entry systematic disinfection solution for Legionella.

  14. Determination of steroid hormones, hormone conjugates and macrolide antibiotics in influents and effluents of sewage treatment plants utilising high-performance liquid chromatography/tandem mass spectrometry with electrospray and atmospheric pressure chemical ionisation.

    PubMed

    Schlüsener, Michael P; Bester, Kai

    2005-01-01

    In this study we present a high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method which has been elaborated to analyse steroid hormones, hormone conjugates, oral contraceptives and macrolide antibiotics unchanged in unfiltered influents and effluents of sewage treatment plants (STPs). HPLC separation of the steroid hormones was achieved in 35 min, as well as those of the antibiotics. The analytes were extracted by solid-phase extraction, followed by clean-up using size exclusion chromatography (SEC). For the final quantification HPLC/MS/MS was used. The two ionisation modes, electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI), in HPLC/MS/MS were compared for the analysis of steroid hormones. For quantitative results drastic matrix effects were observed while using ESI. These effects were less pronounced while using APCI. These pitfalls were additionally reduced by clean-up using SEC as well as isotope dilution. Additionally, two multiple reaction monitoring (MRM) transitions per compound were used to prevent false positive results. Recovery experiments with spiked tap water with concentrations varying from 1 to 1000 ng/L gave constant recovery rates: The recovery rates for the hormones and conjugates ranged from 58 to 107%, those of the contraceptives ranged from 83 to 109%. The relative standard deviation was found to be 7 to 24% and the limits of detection were 0.1 to 4.5 ng/L. The recovery rates of the macrolide antibiotics ranged from 76 to 103%, while the relative standard deviation was found to be 7 to 14% and the limits of detection ranged from 0.6 to 1.8 ng/L. The maximum concentrations found in influents of a STP was 470 ng/L for estriol and 1200 ng/L for erythromycin. Copyright (c) 2005 John Wiley & Sons, Ltd.

  15. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Polarisation of the third harmonic generated by the pump field caused by collisions of electrons and ions in a plasma produced upon ionisation of a gas of excited hydrogen-like atoms

    NASA Astrophysics Data System (ADS)

    Silin, Viktor P.; Silin, Pavel V.

    2005-06-01

    The polarisation properties of the third harmonic of the pump field are considered in a plasma produced upon ionisation of excited hydrogen-like atoms, taking into account l degeneration. These properties depend on the degree of circular polarisation and intensity of the pump field. The threshold nature of the total circular polarisation of the third harmonic appearing in the case of partial circular polarisation of the pump is established. This effect represents the bifurcation of the total circular polarisation. The conditions required to confirm experimentally the predicted polarisation properties of radiation are discussed.

  16. European Code against Cancer 4th Edition: Medical exposures, including hormone therapy, and cancer.

    PubMed

    Friis, Søren; Kesminiene, Ausrele; Espina, Carolina; Auvinen, Anssi; Straif, Kurt; Schüz, Joachim

    2015-12-01

    The 4th edition of the European Code against Cancer recommends limiting - or avoiding when possible - the use of hormone replacement therapy (HRT) because of the increased risk of cancer, nevertheless acknowledging that prescription of HRT may be indicated under certain medical conditions. Current evidence shows that HRT, generally prescribed as menopausal hormone therapy, is associated with an increased risk of cancers of the breast, endometrium, and ovary, with the risk pattern depending on factors such as the type of therapy (oestrogen-only or combined oestrogen-progestogen), duration of treatment, and initiation according to the time of menopause. Carcinogenicity has also been established for anti-neoplastic agents used in cancer therapy, immunosuppressants, oestrogen-progestogen contraceptives, and tamoxifen. Medical use of ionising radiation, an established carcinogen, can provide major health benefits; however, prudent practices need to be in place, with procedures and techniques providing the needed diagnostic information or therapeutic gain with the lowest possible radiation exposure. For pharmaceutical drugs and medical radiation exposure with convincing evidence on their carcinogenicity, health benefits have to be balanced against the risks; potential increases in long-term cancer risk should be considered in the context of the often substantial and immediate health benefits from diagnosis and/or treatment. Thus, apart from HRT, no general recommendations on reducing cancer risk were given for carcinogenic drugs and medical radiation in the 4th edition of European Code against Cancer. It is crucial that the application of these measures relies on medical expertise and thorough benefit-risk evaluation. This also pertains to cancer-preventive drugs, and self-medication with aspirin or other potential chemopreventive drugs is strongly discouraged because of the possibility of serious, potentially lethal, adverse events.

  17. Application of positive ion chemical ionisation and tandem mass spectrometry combined with gas chromatography to the trace level analysis of ethyl carbamate in bread.

    PubMed

    Hamlet, Colin G; Jayaratne, Sanal M; Morrison, Carol

    2005-01-01

    A rapid, sensitive and selective method has been developed and validated for the analysis of the contaminant ethyl carbamate (EC) in bread products at the part-per-billion level. The new procedure uses positive ion chemical ionisation (PICI) and tandem mass spectrometry (MS/MS), combined with gas chromatography (GC), on a 'bench-top' triple-quadrupole mass spectrometer. Ammonia was the PICI reagent gas of choice because of its ability to produce abundant [M+H]+ and [M+NH4]+ ions from EC and deuterium-labelled EC (LEC) used as an internal standard. For identification and quantification, selected reaction monitoring (SRM) was used to follow the precursor-to-product ion transitions of m/z 107 --> 90, m/z 107 --> 62 and m/z 90 --> 62 for EC, as well as m/z 112 --> 63 for the LEC internal standard. The limits of detection and quantification were 0.6 and 1.2 microg kg(-1), respectively, and the recovery of the method was 101 +/- 10% at 10 microg kg(-1) and 98 +/- 5% at 100 microg kg(-1). The precision of the method, established under conditions of intermediate reproducibility, did not exceed a relative standard deviation of 7%. The quantitative performance of the new GC/PICI-SRM procedure compared favourably with that of a reference method based on GC/MS and selected ion monitoring (correlation coefficient, r = 0.997). However, the new method had the advantages of reduced sample preparation time, improved sensitivity and unambiguous identification of EC at all concentrations. Application of the new method to the analysis of 50 UK breads showed that levels of EC ranged from 0.6 to 2.3 microg kg(-1) in retail products and from 3.1 to 12.2 microg kg(-1) for breads prepared using domestic breadmaking machines (dry weight basis). Toasting bread in a domestic toaster led to increases of between two- and three-fold in mean EC concentrations. Copyright (c) 2005 John Wiley & Sons, Ltd.

  18. Structure elucidation of unsaturated fatty acids after vicinal hydroxylation of the double bonds by negative electrospray ionisation low-energy tandem mass spectrometry.

    PubMed

    Moe, Morten K; Jensen, Einar

    2004-01-01

    A method for determining the positions of double bonds in unsaturated fatty acids by use of negative electrospray ionisation low-energy tandem mass spectrometry is described. First, a vicinal hydroxylation of the double bonds of mono- and poly-unsaturated fatty acids was performed. Low-energy collision activation dissociation of the deprotonated molecules produced structurally informative ions formed by a-cleavages relative to the hydroxyl groups. Abundant fragment ions that confirmed the positions of all hydroxyl groups, and thus the positions of the double bonds in the native fatty acids, were observed in the spectra of derivatised mono-, di-, and tri-unsaturated fatty acids. Two types of ions were observed, called [alpha'(n)](-) and [alpha(n)](-). The letter n indicates the positions of the hydroxyl groups. The structurally diagnostic ions [alpha'(n)](-) were produced by cleavages distal to the hydroxyl-groups with the charge retained on the carboxylate. [alpha'(n)](-) ions originating from all hydroxyl-groups were observed in the spectra of modified mono-, di-, and tri-unsaturated fatty acids. Initial proton transfer of a hydroxyl proton to the carboxylate with subsequent cleavages proximal to the hydroxyl groups, relative to the carboxylate, resulted in the two structurally diagnostic [alpha(n)](-) ions. In hydroxylated fatty acids having two or more double bonds in their native structure, [alpha(n)](-) ions originating only from the two final hydroxyl-groups were observed. The formation of all ions of [alpha'(n)](-) and [alpha(n)](-) type can be rationalised by a six-membered transition state. Hydroxylated deprotonated tetra-, penta-, and hexa-unsaturated fatty acids also produced [alpha'(n)](-) ions indicating the positions of most of the hydroxyl-groups, whereas the [alpha(n)](-) ions were observed as described above. The method described offers a simple approach to the determination of the positions of double bonds in unsaturated fatty acids, and is an

  19. In situ formation and characterisation of singly ionised atomic europium in rare gas matrices—Luminescence spectroscopy and MP2 calculations

    SciTech Connect

    Byrne, Owen; Davis, Barry; McCaffrey, John G.

    2015-02-07

    , providing a temporary trap for the ionised electron in the matrices.

  20. The detection of iron protoporphyrin (heme b) in phytoplankton and marine particulate material by electrospray ionisation mass spectrometry - comparison with diode array detection.

    PubMed

    Gledhill, Martha

    2014-09-02

    A mass spectrometric (MS) method for the identification of iron protoporphyrin (IX) (FePTP, heme b) in marine particulate material and phytoplankton is described. Electrospray ionisation of FePTP produced the molecular Fe(III)PTP(+) ion (m/z=616) or the pseudomolecular [Fe(II)PTP + H](+) ion (m/z=617), depending on the oxidation state of the central iron ion. Collision induced dissociation (CID) in the ion trap mass spectrometer resulted in a single detected product ion (m/z=557) indicative of loss of ethanoic acid from a carboxylic acid side chain. Widening the isolation width to 616±3 resulted in production of a mass spectrum demonstrating the distinctive isotopic ratio of the iron containing fragment, further increasing the specificity of the analysis. Selective reactant monitoring (SRM) of the fragment ion (m/z=557) was applied to the detection of FePTP after chromatography of ammoniacal OGP extracts of marine samples. The detection limit for FePTP analysed by SRM after chromatography was 1.2±0.5fmol. For phytoplankton samples, reasonably good agreement was achieved between results obtained with SRM and those obtained by monitoring absorbance at λ=400nm using a diode array detector (DAD). Use of SRM for analysis of particulate material obtained from the high latitude North Atlantic allowed for the analysis of FePTP in the presence of a co-eluting compound that interfered with detection by DAD. Simultaneous collection of mass spectra from m/z=300 to 1500 resulted in identification of the pseudomolecular ion for the interfering compound. The CID fragmentation pattern and UV-visible mass spectra indicated that the interfering compound was a previously unidentified chlorin type compound. Comparison of FePTP determined by SRM and DAD on samples where this compound could not be detected showed that results collected using the two methods correlated. The use of both MS and DAD results in a powerful tool for quantifying this important biogenic component of the

  1. Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing

    PubMed Central

    2012-01-01

    Background Burkholderia (B.) pseudomallei and B. mallei are genetically closely related species. B. pseudomallei causes melioidosis in humans and animals, whereas B. mallei is the causative agent of glanders in equines and rarely also in humans. Both agents have been classified by the CDC as priority category B biological agents. Rapid identification is crucial, because both agents are intrinsically resistant to many antibiotics. Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) has the potential of rapid and reliable identification of pathogens, but is limited by the availability of a database containing validated reference spectra. The aim of this study was to evaluate the use of MALDI-TOF MS for the rapid and reliable identification and differentiation of B. pseudomallei and B. mallei and to build up a reliable reference database for both organisms. Results A collection of ten B. pseudomallei and seventeen B. mallei strains was used to generate a library of reference spectra. Samples of both species could be identified by MALDI-TOF MS, if a dedicated subset of the reference spectra library was used. In comparison with samples representing B. mallei, higher genetic diversity among B. pseudomallei was reflected in the higher average Eucledian distances between the mass spectra and a broader range of identification score values obtained with commercial software for the identification of microorganisms. The type strain of B. pseudomallei (ATCC 23343) was isolated decades ago and is outstanding in the spectrum-based dendrograms probably due to massive methylations as indicated by two intensive series of mass increments of 14 Da specifically and reproducibly found in the spectra of this strain. Conclusions Handling of pathogens under BSL 3 conditions is dangerous and cumbersome but can be minimized by inactivation of bacteria with ethanol, subsequent protein extraction under BSL 1 conditions and MALDI-TOF MS analysis being faster than

  2. NBS1 Heterozygosity and Cancer Risk

    PubMed Central

    di Masi, Alessandra; Antoccia, Antonio

    2008-01-01

    Biallelic mutations in the NBS1 gene are responsible for the Nijmegen breakage syndrome (NBS), a rare autosomal recessive disorder characterized by chromosome instability and hypersensitivity to ionising radiation (IR). Epidemiological data evidence that the NBS1 gene can be considered a susceptibility factor for cancer development, as demonstrated by the fact that almost 40% of NBS patients have developed a malignancy before the age of 21. Interestingly, also NBS1 heterozygotes, which are clinically asymptomatic, display an elevated risk to develop some types of malignant tumours, especially breast, prostate and colorectal cancers, lymphoblastic leukaemia, and non-Hodgkin’s lymphoma (NHL). So far, nine mutations in the NBS1 gene have been found, at the heterozygous state, in cancer patients. Among them, the 657del5, the I171V and the R215W mutations are the most frequently described. The pathogenicity of these mutations is presumably connected with their occurrence in the highly conserved BRCT tandem domains of the NBS1 protein, which are present in a large superfamily of proteins, and are recognized as major mediators of processes related to cell-cycle checkpoint and DNA repair. This review will focus on the current state-of-knowledge regarding the correlation between carriers of NBS1 gene mutations and the proneness to the development of malignant tumours. PMID:19452044

  3. Ionisation induced collapse of minihaloes

    NASA Astrophysics Data System (ADS)

    Back, Trevor

    2013-08-01

    In order to analyse the turbine blade life, the damage due to the combined thermal and mechanical loads should be adequately accounted for. This is more challenging when detailed component geometry is limited. Therefore, a compromise between the level of geometric detail and the complexity of the lifing method to be implemented would be necessary. This research focuses on how the life assessment of aero engine turbine blades can be done, considering the balance between available design inputs and adequate level of fidelity. Accordingly, the thesis contributes to developing a generic turbine blade lifing method that is based on the engine thermodynamic cycle; as well as integrating critical design/technological factors and operational parameters that influence the aero engine blade life. To this end, thermo-mechanical fatigue was identified as the critical damage phenomenon driving the life of the turbine blade.. The developed approach integrates software tools and numerical models created using the minimum design information typically available at the early design stages. Using finite element analysis of an idealised blade geometry, the approach captures relevant impacts of thermal gradients and thermal stresses that contribute to the thermo-mechanical fatigue damage on the gas turbine blade. The blade life is evaluated using the Neu/Sehitoglu thermo-mechanical fatigue model that considers damage accumulation due to fatigue, oxidation, and creep. The leading edge is examined as a critical part of the blade to estimate the damage severity for different design factors and operational parameters. The outputs of the research can be used to better understand how the environment and the operating conditions of the aircraft affect the blade life consumption and therefore what is the impact on the maintenance cost and the availability of the propulsion system. This research also finds that the environmental (oxidation) effect drives the blade life and the blade coolant side was the critical location. Furthermore, a parametric and sensitivity study of the Neu/Sehitoglu model parameters suggests that in addition to four previously reported parameters, the sensitivity of the phasing to oxidation damage would be critical to overall blade life..

  4. Ovarian Cancer

    MedlinePlus

    OVARIAN CANCER Get the Facts About Gynecologic Cancer There are five main types of cancer that affect a ... rare fallopian tube cancer.) This fact sheet about ovarian cancer is part of the Centers for Disease Control ...

  5. Anal cancer

    MedlinePlus

    Cancer - anus; Squamous cell carcinoma - anal; HPV - anal cancer ... Anal cancer can start anywhere in the anus. Where it starts determines the kind of cancer it is. Squamous cell carcinoma. This is the most common type of anal cancer. It ...

  6. Cancer Clusters

    MedlinePlus

    ... Genetics Services Directory Cancer Prevention Overview Research Cancer Clusters On This Page What is a cancer cluster? ... the number of cancer cases in the suspected cluster Many reported clusters include too few cancer cases ...

  7. Oral Cancer

    MedlinePlus

    Oral Cancer Basic description Cancer can affect any part of the oral cavity, including the lips, tongue, mouth, and throat. There are 2 kinds of oral cancer: oral cavity cancer and oropharyngeal cancer. The most ...

  8. Oral cancer

    MedlinePlus

    Cancer - mouth; Mouth cancer; Head and neck cancer; Squamous cell cancer - mouth; Malignant neoplasm - oral ... Oral cancer most commonly involves the lips or the tongue. It may also occur on the: Cheek lining Floor ...

  9. Determination and separation of bisphenol A, phthalate metabolites and structural isomers of parabens in human urine with conventional high-pressure liquid chromatography combined with electrospray ionisation tandem mass spectrometry.

    PubMed

    Myridakis, Antonis; Balaska, Eirini; Gkaitatzi, Christina; Kouvarakis, Antonis; Stephanou, Euripides G

    2015-03-01

    Phthalates, bisphenol A (BPA) and parabens (PBs), organic chemicals widely used in everyday products, are considered to be endocrine disruptors. We propose a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of seven phthalate metabolites, six PBs and BPA in human urine. All three categories of the above endocrine disruptors were simultaneously extracted from 1 mL of human urine using solid phase extraction. In addition, with a conventional reversed phase LC column, we achieved for the first time the separation of three pairs of structural isomers, namely iso-/n-butyl paraben, propyl paraben and monobutyl phthalate. LC-MS/MS was operated and tested in both electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI). ESI was selected for the analysis due to its superior stability and repeatability. The method limit of detection (mLOD), achieved for a single set of high-performance LC conditions, ranged from 0.01 to 0.84 ng/mL for phthalate metabolites, from 0.06 to 0.24 ng/mL for PBs and was 2.01 ng/mL for BPA. Derivatisation of BPA with dansyl chloride lowered its mLOD to 0.007 ng/mL. Blank contamination was non-detectable. The present method was successfully applied for the analysis of the above-mentioned compounds in 80 male human urine samples.

  10. Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing.

    PubMed

    Adam, T W; Clairotte, M; Streibel, T; Elsasser, M; Pommeres, A; Manfredi, U; Carriero, M; Martini, G; Sklorz, M; Krasenbrink, A; Astorga, C; Zimmermann, R

    2012-07-01

    Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.

  11. Multiscale approach predictions for biological outcomes in ion-beam cancer therapy

    PubMed Central

    Verkhovtsev, Alexey; Surdutovich, Eugene; Solov’yov, Andrey V.

    2016-01-01

    Ion-beam therapy provides advances in cancer treatment, offering the possibility of excellent dose localization and thus maximising cell-killing within the tumour. The full potential of such therapy can only be realised if the fundamental mechanisms leading to lethal cell damage under ion irradiation are well understood. The key question is whether it is possible to quantitatively predict macroscopic biological effects caused by ion radiation on the basis of physical and chemical effects related to the ion-medium interactions on a nanometre scale. We demonstrate that the phenomenon-based MultiScale Approach to the assessment of radiation damage with ions gives a positive answer to this question. We apply this approach to numerous experiments where survival curves were obtained for different cell lines and conditions. Contrary to other, in essence empirical methods for evaluation of macroscopic effects of ionising radiation, the MultiScale Approach predicts the biodamage based on the physical effects related to ionisation of the medium, transport of secondary particles, chemical interactions, thermo-mechanical pathways of biodamage, and heuristic biological criteria for cell survival. We anticipate this method to give great impetus to the practical improvement of ion-beam cancer therapy and the development of more efficient treatment protocols. PMID:27297618

  12. Multiscale approach predictions for biological outcomes in ion-beam cancer therapy

    NASA Astrophysics Data System (ADS)

    Verkhovtsev, Alexey; Surdutovich, Eugene; Solov’Yov, Andrey V.

    2016-06-01

    Ion-beam therapy provides advances in cancer treatment, offering the possibility of excellent dose localization and thus maximising cell-killing within the tumour. The full potential of such therapy can only be realised if the fundamental mechanisms leading to lethal cell damage under ion irradiation are well understood. The key question is whether it is possible to quantitatively predict macroscopic biological effects caused by ion radiation on the basis of physical and chemical effects related to the ion-medium interactions on a nanometre scale. We demonstrate that the phenomenon-based MultiScale Approach to the assessment of radiation damage with ions gives a positive answer to this question. We apply this approach to numerous experiments where survival curves were obtained for different cell lines and conditions. Contrary to other, in essence empirical methods for evaluation of macroscopic effects of ionising radiation, the MultiScale Approach predicts the biodamage based on the physical effects related to ionisation of the medium, transport of secondary particles, chemical interactions, thermo-mechanical pathways of biodamage, and heuristic biological criteria for cell survival. We anticipate this method to give great impetus to the practical improvement of ion-beam cancer therapy and the development of more efficient treatment protocols.

  13. Meta-analysis of non-tumour doses for radiation-induced cancer on the basis of dose-rate.

    PubMed

    Tanooka, Hiroshi

    2011-07-01

    Quantitative analysis of cancer risk of ionising radiation as a function of dose-rate. Non-tumour dose, D(nt), defined as the highest dose of radiation at which no statistically significant tumour increase was observed above the control level, was analysed as a function of dose-rate of radiation. An inverse correlation was found between D(nt) and dose-rate of the radiation. D(nt) increased 20-fold with decreasing dose-rate from 1-10(-8) Gy/min for whole body irradiation with low linear energy transfer (LET) radiation. Partial body radiation also showed a dose-rate dependence with a 5- to 10-fold larger D(nt) as dose rate decreased. The dose-rate effect was also found for high LET radiation but at 10-fold lower D(nt) levels. The cancer risk of ionising radiation varies 1000-fold depending on the dose-rate of radiation and exposure conditions. This analysis explains the discrepancy of cancer risk between A-bomb survivors and radium dial painters.

  14. 6 Common Cancers - Breast Cancer

    MedlinePlus

    ... Home Current Issue Past Issues 6 Common Cancers - Breast Cancer Past Issues / Spring 2007 Table of Contents For ... slow her down. Photo: AP Photo/Brett Flashnick Breast Cancer Breast cancer is a malignant (cancerous) growth that ...

  15. 6 Common Cancers - Colorectal Cancer

    MedlinePlus

    ... Bar Home Current Issue Past Issues 6 Common Cancers - Colorectal Cancer Past Issues / Spring 2007 Table of Contents For ... colon cancer. Photo: AP Photo/Ron Edmonds Colorectal Cancer Cancer of the colon (large intestine) or rectum ( ...

  16. Is cancer risk of radiation workers larger than expected?

    PubMed Central

    Jacob, P; Rühm, W; Walsh, L; Blettner, M; Hammer, G; Zeeb, H

    2009-01-01

    Occupational exposures to ionising radiation mainly occur at low-dose rates and may accumulate effective doses of up to several hundred milligray. The objective of the present study is to evaluate the evidence of cancer risks from such low-dose-rate, moderate-dose (LDRMD) exposures. Our literature search for primary epidemiological studies on cancer incidence and mortality risks from LDRMD exposures included publications from 2002 to 2007, and an update of the UK National Registry for Radiation Workers study. For each (LDRMD) study we calculated the risk for the same types of cancer among the atomic bomb survivors with the same gender proportion and matched quantities for dose, mean age attained and mean age at exposure. A combined estimator of the ratio of the excess relative risk per dose from the LDRMD study to the corresponding value for the atomic bomb survivors was 1.21 (90% CI 0.51 to 1.90). The present analysis does not confirm that the cancer risk per dose for LDRMD exposures is lower than for the atomic bomb survivors. This result challenges the cancer risk values currently assumed for occupational exposures. PMID:19570756

  17. Gallbladder Cancer: Surgery

    MedlinePlus

    ... for Gallbladder Cancer Chemotherapy for Gallbladder Cancer Palliative Therapy for Gallbladder Cancer Treatment Options Based on the Extent of Gallbladder Cancer ... Cancer Information Cancer Prevention & Detection Cancer Basics ...

  18. PARP inhibitors in cancer therapy: two modes of attack on the cancer cell widening the clinical applications.

    PubMed

    Drew, Yvette; Plummer, Ruth

    2009-12-01

    The abundant nuclear enzyme poly(ADP-ribose)polymerase-1 (PARP-1) represents an important novel target in cancer therapy. PARP-1 is essential to the repair of single strand DNA breaks via the base excision repair pathway. Inhibitors of PARP-1 have been shown to enhance the cytotoxic effects of ionising radiation and DNA damaging chemotherapy agents such as the methylating agents and topoisomerase-I inhibitors. There are currently at least eight PARP inhibitors in clinical trial development. In vitro data, in vivo preclinical data and most recently early clinical trial data suggests that PARP inhibitors could be used not only as chemo/radiotherapy sensitizers but also as single agents to selectively kill cancers defective in DNA repair, specifically cancers with mutations in the breast cancer associated (BRCA)1 and BRCA2 genes. This theory of selectively exploiting cells defective in one DNA repair pathway by inhibiting another is a major breakthrough in the treatment of cancer. The current clinical data are discussed within this review with reference to the preclinical models which predicted activity and also future directions and the possible dangers/pitfalls of this clinical strategy are explored.

  19. Anal Cancer

    MedlinePlus

    ... are here Home > Types of Cancer > Anal Cancer Anal Cancer This is Cancer.Net’s Guide to Anal Cancer. Use the menu below to choose the ... social workers, and patient advocates. Cancer.Net Guide Anal Cancer Introduction Statistics Risk Factors and Prevention Screening ...

  20. Thyroid Cancer

    MedlinePlus

    ... are here Home > Types of Cancer > Thyroid Cancer Thyroid Cancer This is Cancer.Net’s Guide to Thyroid Cancer. Use the menu below to choose the ... social workers, and patient advocates. Cancer.Net Guide Thyroid Cancer Introduction Statistics Medical Illustrations Risk Factors Symptoms ...

  1. Laser ablation synthesis of new gold phosphides using red phosphorus and nanogold as precursors. Laser desorption ionisation time-of-flight mass spectrometry.

    PubMed

    Panyala, Nagender Reddy; Peña-Méndez, Eladia María; Havel, Josef

    2012-05-15

    Gold phosphides show unique optical or semiconductor properties and there are extensive high technology applications, e.g. in laser diodes, etc. In spite of the various AuP structures known, the search for new materials is wide. Laser ablation synthesis is a promising screening and synthetic method. Generation of gold phosphides via laser ablation of red phosphorus and nanogold mixtures was studied using laser desorption ionisation time-of-flight mass spectrometry (LDI TOFMS). Gold clusters Au(m)(+) (m = 1 to ~35) were observed with a difference of one gold atom and their intensities were in decreasing order with respect to m. For P(n)(+) (n = 2 to ~111) clusters, the intensities of odd-numbered phosphorus clusters are much higher than those for even-numbered phosphorus clusters. During ablation of P-nanogold mixtures, clusters Au(m)(+) (m = 1-12), P(n)(+) (n = 2-7, 9, 11, 13-33, 35-95 (odd numbers)), AuP(n)(+) (n = 1, 2-88 (even numbers)), Au(2)P(n)(+) (n = 1-7, 14-16, 21-51 (odd numbers)), Au(3)P(n)(+) (n = 1-6, 8, 9, 14), Au(4)P(n)(+) (n = 1-9, 14-16), Au(5)P(n)(+) (n = 1-6, 14, 16), Au(6)P(n)(+) (n = 1-6), Au(7)P(n)(+) (n = 1-7), Au(8)P(n)(+) (n = 1-6, 8), Au(9)P(n)(+) (n = 1-10), Au(10)P(n)(+) (n = 1-8, 15), Au(11)P(n)(+) (n = 1-6), and Au(12)P(n)(+) (n = 1, 2, 4) were detected in positive ion mode. In negative ion mode, Au(m)(-) (m = 1-5), P(n)(-) (n = 2, 3, 5-11, 13-19, 21-35, 39, 41, 47, 49, 55 (odd numbers)), AuP(n)(-) (n = 4-6, 8-26, 30-36 (even numbers), 48), Au(2)P(n)(-) (n = 2-5, 8, 11, 13, 15, 17), A(3) P(n)(-) (n = 6-11, 32), Au(4)P(n)(-) (n = 1, 2, 4, 6, 10), Au(6)P(5)(-), and Au(7)P(8)(-) clusters were observed. In both modes, phosphorus-rich Au(m)P(n) clusters prevailed. The first experimental evidence for formation of AuP(60) and gold-covered phosphorus Au(12)P(n) (n = 1, 2, 4) clusters is given. The new gold phosphides generated might inspire synthesis of

  2. Breast Cancer

    MedlinePlus

    ... version of this page please turn Javascript on. Breast Cancer What is Breast Cancer? How Tumors Form The body is made up ... tumors form in the breast tissue. Who Gets Breast Cancer? Breast cancer is one of the most common ...

  3. Childhood Cancer

    MedlinePlus

    ... most common childhood cancers are leukemia , lymphoma , and brain cancer . As kids enter the teen years, osteosarcoma (bone ... With Cancer Adjust Leukemia Chemotherapy Radiation Therapy Osteosarcoma Brain Tumors Cancer Center Acute Myeloid Leukemia (AML) Balancing Academics and ...

  4. Ovarian cancer

    MedlinePlus

    ... cancer, CT scan Ovarian cancer dangers Ovarian growth worries Uterus Ovarian cancer Ovarian cancer metastasis References Coleman ... Duplication for commercial use must be authorized in writing by ADAM Health Solutions. About MedlinePlus Site Map ...

  5. Thyroid cancer

    MedlinePlus

    ... a family history of thyroid cancer and chronic goiter (enlarged thyroid). There are several types of thyroid ... Read More Anaplastic thyroid cancer Breathing difficulty Cancer Goiter - simple Metastasis Radiation therapy Thyroid cancer - papillary carcinoma ...

  6. Skin Cancer

    MedlinePlus

    ... version of this page please turn Javascript on. Skin Cancer What is Skin Cancer? Skin cancer is the most common type ... of approximately 9,480 Americans in 2013. Can Skin Cancer Be Treated? Most basal cell and squamous ...

  7. Prostate Cancer

    MedlinePlus

    ... version of this page please turn Javascript on. Prostate Cancer What is Prostate Cancer? How Tumors Form The body is made up ... the Escape (Esc) button on your keyboard.) How Prostate Cancer Occurs Prostate cancer occurs when a tumor forms ...

  8. Anal Cancer

    MedlinePlus

    ... 2345 Phone Search Search Category Cancer A-Z Anal Cancer If you have anal cancer or are close to someone who does, ... cope. Here you can find out all about anal cancer, including risk factors, symptoms, how it is ...

  9. Testicular cancer

    MedlinePlus

    Cancer - testes; Germ cell tumor; Seminoma testicular cancer; Nonseminoma testicular cancer; Testicular neoplasm ... The exact cause of testicular cancer is unknown. Factors that may ... Abnormal testicle development Exposure to certain chemicals ...

  10. Matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry as a tool for rapid diagnosis of potentially toxigenic Corynebacterium species in the laboratory management of diphtheria-associated bacteria.

    PubMed

    Konrad, R; Berger, A; Huber, I; Boschert, V; Hörmansdorfer, S; Busch, U; Hogardt, M; Schubert, S; Sing, A

    2010-10-28

    The rapid identification of the potentially toxigenic Corynebacterium species, C. diphtheriae, C. ulcerans and C. pseudotuberculosis is essential for diagnosis and treatment of diphtheria and diphtheria-like diseases. We used matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDIT-OF MS) in comparison with classical microbiological and molecular methods on 116 Corynebacterium strains. All 90 potentially toxigenic Corynebacterium strains collected by the German National Consiliary Laboratory on Diphtheria in a period of more than ten years were correctly identified by MALDI-TOF MS. We propose an algorithm for fast and reliable diagnosis of diphtheria incorporating MALDI-TOF MS, real-time tox PCR and Elek testing.

  11. Investigating time patterns of variation in radiation cancer associations

    PubMed Central

    Richardson, D; Ashmore, J

    2005-01-01

    Aims: In occupational settings, carcinogenic exposures are often repeated or protracted over time. The time pattern of exposure accrual may influence subsequent temporal patterns of cancer risk. The authors present several simple models that may be used to evaluate the influence of time since exposure or age at exposure on cancer incidence or mortality in an occupational cohort. Methods: A cohort of 40 415 nuclear industry workers was identified via the Canadian National Dose Registry. Vital status and cause of death were ascertained through 1994. Associations between ionising radiation and mortality due to lung cancer, leukaemia, and cancers other than lung and leukaemia were quantified using conditional logistic regression models with risk sets constructed by incidence density sampling. A step function, a bilinear function, and a sigmoid function were used to evaluate temporal variation in exposure effects. Results: Step and sigmoid functions were used to explore latency and morbidity periods. For analyses of lung cancer, leukaemia, and other cancers the best fitting models were obtained when exposure assignment was lagged by 13, 0, and 5 years, respectively. A bilinear function was used to evaluate whether exposure effects diminished with time since exposure. In analyses of lung cancer and leukaemia, there was evidence that radiation effects attenuated with protracted time since exposure. In analyses of age at exposure, there was evidence of variation in radiation mortality associations for analyses of lung cancer and leukaemia; discounting radiation doses accrued at younger ages (for example, 15–35 years) led to significant improvements in model fit. Conclusions: This paper illustrates empirical approaches to evaluating temporal variation in the effect of a protracted exposure on disease risk. PMID:16046608

  12. Lung cancer

    SciTech Connect

    Aisner, J.

    1985-01-01

    This book contains 13 chapters. Some of the chapter titles are: The Pathology of Lung Cancer; Radiotherapy for Non-Small-Cell Cancer of the Lung; Chemotherapy for Non-Small-Cell Lung Cancer; Immunotherapy in the Management of Lung Cancer; Preoperative Staging and Surgery for Non-Small-Cell Lung Cancer; and Prognostic Factors in Lung Cancer.

  13. Cancer incidence risks to patients due to hysterosalpingography

    PubMed Central

    Gyekye, Prince K.; Emi-Reynolds, Geoffrey; Boadu, Mary; Darko, Emmanuel O.; Yeboah, Johnson; Inkoom, Stephen; Mensah, Cynthia K.

    2012-01-01

    Cancer incidence estimates and dosimetry of 120 patients undergoing hysterosalpingography (HSG) without screening at five rural hospitals and with screening using image intensifier-TV at an urban hospital have been studied. Free in air kerma measurements were taken for patient dosimetry. Using PCXMC version 1.5, organ and effective doses to patients were estimated. Incidence of cancer of the ovary, colon, bladder and uterus due to radiation exposure were estimated using biological effects of ionising radiation committee VII excess relative risk models. The effective dose to patients was estimated to be 0.20 ± 0.03 mSv and 0.06 ± 0.01 mSv for procedures with and without screening, respectively. The average number of exposures for both procedures, 2.5, and screening time of 48.1 s were recorded. Screening time contributed majority of the patient doses due to HSG; therefore, it should be optimised as much as possible. Of all the cancers considered, the incidence of cancer of the bladder for patients undergoing HSG procedures is more probable. PMID:22557802

  14. Immunoscore in Rectal Cancer

    ClinicalTrials.gov

    2017-06-13

    Cancer of the Rectum; Neoplasms, Rectal; Rectal Cancer; Rectal Tumors; Rectal Adenocarcinoma; Melanoma; Breast Cancer; Renal Cell Cancer; Lung Cancer; Bladder Cancer; Head and Neck Cancer; Ovarian Cancer; Thyroid Cancer

  15. Radon and Cancer

    MedlinePlus

    ... Cancer Kidney (Renal Cell) Cancer Leukemia Liver Cancer Lung Cancer Lymphoma Pancreatic Cancer Prostate Cancer Skin Cancer Thyroid ... does radon cause cancer? How many people develop lung cancer because of exposure to radon? How did scientists ...

  16. 6 Common Cancers - Lung Cancer

    MedlinePlus

    ... Home Current Issue Past Issues 6 Common Cancers - Lung Cancer Past Issues / Spring 2007 Table of Contents ... for Desperate Housewives. (Photo ©2005 Kathy Hutchins / Hutchins) Lung Cancer Lung cancer causes more deaths than the ...

  17. 6 Common Cancers - Skin Cancer

    MedlinePlus

    ... Bar Home Current Issue Past Issues 6 Common Cancers - Skin Cancer Past Issues / Spring 2007 Table of Contents For ... AP Photo/Herald-Mail, Kevin G. Gilbert Skin Cancer Skin cancer is the most common form of ...

  18. Evidence for site-specific intra-ionic hydrogen/deuterium exchange in the low-energy collision-induced dissociation product ion spectra of protonated small molecules generated by electrospray ionisation.

    PubMed

    Holman, Stephen W; Wright, Patricia; Wells, Neil J; Langley, G John

    2010-04-01

    The experimental investigation of site-specific intra-ionic hydrogen/deuterium (H/D) exchange in the low-energy collision-induced dissociation (CID) product ion spectra of protonated small molecules generated by electrospray ionisation (ESI) is presented. The observation of intra-ionic H/D exchange in such ions under low-energy CID conditions has hitherto been rarely reported. The data suggest that the intra-ionic H/D exchange takes place in a site-specific manner between the ionising deuteron, localised at either a tertiary amine or a tertiary amine-N-oxide, and a gamma-hydrogen relative to the nitrogen atom. Nuclear magnetic resonance (NMR) spectroscopy measurements showed that no H/D exchange takes place in solution, indicating that the reaction occurs in the gas phase. The compounds analysed in this study suggested that electron-withdrawing groups bonded to the carbon atom bearing the gamma-hydrogen can preclude exchange. The effect of the electron-withdrawing group appears dependent upon its electronegativity, with lower chi value groups still allowing exchange to take place. However, the limited dataset available in this study prevented robust conclusions being drawn regarding the effect of the electron-withdrawing group. The observation of site-specific intra-ionic H/D exchange has application in the area of structural elucidation, where it could be used to introduce an isotopic label into the carbon skeleton of a molecule containing specific structural features. This could increase the throughput, and minimise the cost, of such studies due to the obviation of the need to produce a deuterium-labelled analogue by synthetic means. Copyright 2010 John Wiley & Sons, Ltd.

  19. Quality of Life in Patients Undergoing Radiation Therapy for Primary Lung Cancer, Head and Neck Cancer, or Gastrointestinal Cancer

    ClinicalTrials.gov

    2017-05-23

    Anal Cancer; Colorectal Cancer; Esophageal Cancer; Extrahepatic Bile Duct Cancer; Gallbladder Cancer; Gastric Cancer; Head and Neck Cancer; Liver Cancer; Lung Cancer; Pancreatic Cancer; Small Intestine Cancer

  20. Epidemiological studies of Fukushima residents exposed to ionising radiation from the Fukushima Daiichi Nuclear Power Plant prefecture--a preliminary review of current plans.

    PubMed

    Akiba, Suminori

    2012-03-01

    It is now more than six months since the beginning of the accident on 11 March 2011 at the Fukushima Daiichi Nuclear Power Plant in Japan. The Japanese government and local health authorities have started to collect the information necessary to estimate radiation doses received by those living in the area around the plant, drafted plans for the health care of residents, and started to implement some of them. This paper reviews and discusses the studies necessary for risk evaluation of cancer and non-cancer diseases, including those already planned, mainly from the view point of evaluating health risk using epidemiological approaches. In the long run, it is important to establish a cohort with a control group. Even if the cumulative doses are estimated to be so low that it is difficult to evaluate the risk of cancer and non-cancer diseases, it is necessary to conduct such a study to reassure residents. The health care programme of the Fukushima Prefecture government, including health check-ups of residents, will help to assess indirect effects of radiation exposure, including psychological problems. The success of any studies of radiation epidemiology depends on the collection of accurate information on radiation doses received by the study subjects. However, some of the dosimetry surveys were not conducted in a timely manner. (It should be recognised, though, that such a problem might have been inevitable, considering the chaotic condition after the nuclear accident.) Accurate estimation of the radiation dose received by each resident is not only important for scientific risk evaluation but also to inform each resident about his or her potential risk. Otherwise, residents will bear an undue psychological burden from uncertainties regarding their radiation exposure and its health consequences. One of other important tasks in Fukushima is the improvement of the quality of the regional cancer registry in this prefecture. It is also important to start thyroid cancer

  1. Antioxidants and Cancer Prevention

    MedlinePlus

    ... Research Areas Cancer Biology Cancer Genomics Causes of Cancer Diagnosis Prevention Screening & Early Detection Treatment Cancer & Public Health ... Research Areas Cancer Biology Cancer Genomics Causes of Cancer Diagnosis Prevention Screening & Early Detection Treatment Cancer & Public Health ...

  2. Ovarian Cancer

    MedlinePlus

    ... deaths than other female reproductive cancers. The sooner ovarian cancer is found and treated, the better your chance for recovery. But ovarian cancer is hard to detect early. Women with ovarian ...

  3. Skin Cancer

    MedlinePlus

    ... States. The two most common types are basal cell cancer and squamous cell cancer. They usually form on the head, face, ... If not treated, some types of skin cancer cells can spread to other tissues and organs. Treatments ...

  4. Breast cancer

    MedlinePlus

    ... idea of what to expect in the future. Breast cancer stages range from 0 to IV. The higher the ... is based on many factors, including: Type of breast cancer Stage of the cancer (staging is a tool your ...

  5. Cancer Chemotherapy

    MedlinePlus

    ... controlled way. Cancer cells keep growing without control. Chemotherapy is drug therapy for cancer. It works by killing the cancer ... It depends on the type and amount of chemotherapy you get and how your body reacts. Some ...

  6. Kidney Cancer

    MedlinePlus

    ... common cancers in the United States. Cancer Home Kidney Cancer Language: English (US) Español (Spanish) Recommend ... work with the chemical trichloroethylene. What Are the Kidneys? The body has two kidneys, one on each ...

  7. Lung Cancer

    MedlinePlus

    ... version of this page please turn Javascript on. Lung Cancer What is Lung Cancer? How Tumors Form The body is made ... button on your keyboard.) Two Major Types of Lung Cancer There are two major types of lung ...

  8. Oral Cancer

    MedlinePlus

    Oral cancer can form in any part of the mouth. Most oral cancers begin in the flat cells that cover the ... your mouth, tongue, and lips. Anyone can get oral cancer, but the risk is higher if you are ...

  9. Esophageal cancer

    MedlinePlus

    Cancer - esophagus ... Esophageal cancer is not common in the United States. It occurs most often in men over 50 years old. There are two main types of esophageal cancer: squamous cell carcinoma and adenocarcinoma. These two types ...

  10. Stomach cancer

    MedlinePlus

    Cancer - stomach; Gastric cancer; Gastric carcinoma; Adenocarcinoma of the stomach ... Several types of cancer can occur in the stomach. The most common type is called adenocarcinoma. It starts from one of the cell ...

  11. Stomach Cancer

    MedlinePlus

    ... with stomach acid and helps digest protein. Stomach cancer mostly affects older people - two-thirds of people ... Smoke cigarettes Have a family history of stomach cancer It is hard to diagnose stomach cancer in ...

  12. Bone Cancer

    MedlinePlus

    Cancer that starts in a bone is uncommon. Cancer that has spread to the bone from another ... more common. There are three types of bone cancer: Osteosarcoma - occurs most often between ages 10 and ...

  13. Uterine Cancer

    MedlinePlus

    ... is pregnant. There are different types of uterine cancer. The most common type starts in the endometrium, ... the uterus. This type is also called endometrial cancer. The symptoms of uterine cancer include Abnormal vaginal ...

  14. Cancer Immunotherapy

    MedlinePlus

    Immunotherapy is a cancer treatment that helps your immune system fight cancer. It is a type of biological therapy. Biological therapy uses substances ... t yet use immunotherapy as often as other cancer treatments, such as surgery, chemotherapy, and radiation therapy. ...

  15. Thyroid Cancer

    MedlinePlus

    ... body work normally. There are several types of cancer of the thyroid gland. You are at greater ... imaging tests, and a biopsy to diagnose thyroid cancer. Treatment depends on the type of cancer you ...

  16. Vulvar Cancer

    MedlinePlus

    ... a biopsy. Treatment varies, depending on your overall health and how advanced the cancer is. It might include surgery, radiation therapy, chemotherapy, or biologic therapy. Biologic therapy boosts your body's own ability to fight cancer. NIH: National Cancer Institute

  17. Integrated Molecular Profiling in Advanced Cancers Trial

    ClinicalTrials.gov

    2016-08-19

    Breast Cancer; Non-small Cell Lung Cancer; Colorectal Cancer; Genitourinary Cancer; Pancreatobiliary Gastrointestinal Cancer; Upper Aerodigestive Tract Cancer; Gynecological Cancers; Melanoma Cancers; Rare Cancers; Unknown Primary Cancers

  18. Cancer Treatment - Cancer Currents Blog

    Cancer.gov

    A catalog of posts from NCI’s Cancer Currents blog on cancer treatment research. Includes posts on new treatments for cancer and their effects, clinical trial results, and overcoming treatment resistance.

  19. Cancer Disparities - Cancer Currents Blog

    Cancer.gov

    Blog posts on cancer health disparities research—including factors that influence disparities, disparities-related research efforts, and diversity in the cancer research workforce—from NCI Cancer Currents.

  20. Cancer Technology - Cancer Currents Blog

    Cancer.gov

    Blog posts on technologies that affect cancer research and care—including new technologies for detecting cancer, testing treatments, storing/analyzing data, and improving patient care—from NCI Cancer Currents.

  1. 6 Common Cancers - Prostate Cancer

    MedlinePlus

    ... Bar Home Current Issue Past Issues 6 Common Cancers - Prostate Cancer Past Issues / Spring 2007 Table of Contents For ... early screening. Photo: AP Photo/Danny Moloshok Prostate Cancer The prostate gland is a walnut-sized structure ...

  2. Cancer Prevention - Cancer Currents Blog

    Cancer.gov

    A catalog of posts from NCI’s Cancer Currents blog on research related to cancer prevention. Includes posts on behavioral interventions and other ways to prevent cancer and prevention-related research programs.

  3. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: On the bifurcation of the circular polarisation of the fifth and seventh pump-field harmonics generated in the plasma produced by the ionisation of a gas of excited hydrogen-like atoms

    NASA Astrophysics Data System (ADS)

    Silin, Viktor P.; Silin, Pavel V.

    2006-05-01

    Within the framework of the Bethe ionisation model we considered theoretically the dependences of the degree of circular polarisation of the fifth and seventh pump-field harmonics, which are generated due to bremsstrahlung, on the electric intensity of the pump field, the degree of its circular polarisation, and the principal quantum number of the excited states of hydrogen-like atoms of a gas ionised by the pump field. A bifurcation of the circular polarisation of these harmonics was discovered, which confirms our previous hypothesis that this effect is common for harmonics generated due to the bremsstrahlung in the pump field when the plasma electrons oscillate in this field. We determined how the relationships under consideration are scaled with VEn/VZ, the product of electron oscillation velocity and the principal quantum number of the excited electron divided by the Coulomb velocity.

  4. Testicular Cancer Screening

    MedlinePlus

    ... Laboratory for Cancer Research Partners & Collaborators Spotlight on Scientists Research Areas Cancer Biology Cancer Genomics Causes of Cancer Diagnosis Prevention Screening & Early Detection Treatment Cancer & Public Health ...

  5. Radiation Therapy for Testicular Cancer

    MedlinePlus

    ... Treating Testicular Cancer Surgery for Testicular Cancer Radiation Therapy for Testicular Cancer Chemotherapy for Testicular Cancer High-Dose Chemotherapy and ... Cancer Information Cancer Prevention & Detection Cancer Basics ...

  6. Childhood Cancer

    MedlinePlus

    ... they demand more and more of the body's nutrition. Cancer takes a person's strength, destroys organs and bones, and weakens the body's defenses against other illnesses. Cancer is uncommon in children, but can happen. The most common childhood cancers are leukemia , lymphoma , and brain cancer . As ...

  7. Prostate Cancer

    MedlinePlus

    Prostate cancer Overview Prostate cancer is cancer that occurs in the prostate — a small walnut-shaped gland in men that produces the seminal fluid that nourishes and transports sperm. Prostate cancer is one of the most common types of ...

  8. Anal Cancer

    MedlinePlus

    Anal cancer Overview Anal cancer is an uncommon type of cancer that occurs in the anal canal. The anal canal is a short tube at the end ... your rectum through which stool leaves your body. Anal cancer can cause signs and symptoms such as ...

  9. Cervical Cancer

    MedlinePlus

    ... cervical cancers are caused by the human papillomavirus (HPV). Cervical cancer is the easiest gynecological cancer to prevent with ... HPV on a woman's cervix. Certain types of HPV can lead to cervical cancer. Your doctor will swab the cervix for cells. ...

  10. Gastric cancer

    SciTech Connect

    Douglass, H.O. )

    1988-01-01

    This book contains 10 selections. Some of the titles are: Radiation therapy for gastric cancer; Experimental stomach cancer: Drug selection based on in vitro testing; Western surgical adjuvant trials in gastric cancers: Lessons from current trials to be applied in the future; and Chemotherapy of gastric cancer.

  11. Gastrointestinal cancer

    SciTech Connect

    Levin, B.

    1988-01-01

    This book contains 33 selections. Some of the titles are: The natural history of colorectal cancer; opportunities for intervention; Radiotherapy for early rectal cancer; Intraoperative irradiation for gastrointestinal cancers; Hepatocellular carcinoma; clinical presentation, etiology, and prevention; and Current issues in the treatment of patients with gastric cancer.

  12. Lung Cancer

    MedlinePlus

    Lung cancer is one of the most common cancers in the world. It is a leading cause of cancer death in men and women in the United States. Cigarette smoking causes most lung cancers. The more cigarettes you smoke per day and ...

  13. Vaginal Cancer

    MedlinePlus

    Vaginal cancer is a rare type of cancer. It is more common in women 60 and older. You are also more likely to get it if you have had a human ... test can find abnormal cells that may be cancer. Vaginal cancer can often be cured in its ...

  14. What Is Breast Cancer?

    MedlinePlus

    ... Research? Breast Cancer About Breast Cancer What Is Breast Cancer? Breast cancer starts when cells in the breast ... spread, see our section on Cancer Basics . Where breast cancer starts Breast cancers can start from different parts ...

  15. What Is Thyroid Cancer?

    MedlinePlus

    ... Treatment? Thyroid Cancer About Thyroid Cancer What Is Thyroid Cancer? Cancer starts when cells in the body begin ... cell) Medullary Anaplastic (an aggressive undifferentiated tumor) Differentiated thyroid cancers Most thyroid cancers are differentiated cancers. The cells ...

  16. Prostate cancer - resources

    MedlinePlus

    Resources - prostate cancer ... The following organizations are good resources for information on prostate cancer : American Cancer Society -- www.cancer.org/cancer/prostatecancer/index National Cancer Institute -- www.cancer.gov/cancertopics/ ...

  17. Diet and cancer

    MedlinePlus

    Fiber and cancer; Cancer and fiber; Nitrates and cancer; Cancer and nitrates ... DIET AND BREAST CANCER The link between nutrition and breast cancer has been well studied. To reduce risk of breast cancer the American ...

  18. Classification of protein binders in artist's paints by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry: an evaluation of principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA).

    PubMed

    Fremout, Wim; Kuckova, Stepanka; Crhova, Michaela; Sanyova, Jana; Saverwyns, Steven; Hynek, Radovan; Kodicek, Milan; Vandenabeele, Peter; Moens, Luc

    2011-06-15

    Proteomics techniques are increasingly applied for the identification of protein binders in historical paints. The complex nature of paint samples, with different kinds of pigments mixed into, and degradation by long term exposure to light, humidity and temperature variations, requires solid analysis and interpretation methods. In this study matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectra of tryptic-digested paint replicas are subjected to principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) in order to distinguish proteinaceous binders based on animal glues, egg white, egg yolk and milk casein from each other. The most meaningful peptide peaks for a given protein class will be determined, and if possible, annotated with their corresponding amino acid sequence. The methodology was subsequently applied on egg temperas, as well as on animal glues from different species. In the latter small differences in the MALDI-TOF mass spectra can allow the determination of a mammal or sturgeon origin of the glue. Finally, paint samples from the 16(th) century altarpiece of St Margaret of Antioch (Mlynica, Slovakia) were analysed. Several expected peaks are either present in lower abundance or completely missing in these natural aged paints, due to degradation of the paints. In spite of this mammalian glue was identified in the St Margaret samples.

  19. Fast confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine by LC/MS/MS using negative atmospheric-pressure chemical ionisation (APCI).

    PubMed

    Weinmann, W; Goerner, M; Vogt, S; Goerke, R; Pollak, S

    2001-09-15

    A fast method using automated solid-phase extraction (SPE) and short-column liquid-chromatography coupled to tandem mass-spectrometry (LC/MS/MS) with negative atmospheric-pressure chemical ionisation (APCI) has been developed for the confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine samples. This highly specific method which combines chromatographic separation and MS/MS-analysis can be used for the confirmation of positive immunoassay results with a NIDA cut-off of 15ng/ml. The conjugates of THC-COOH were hydrolysed prior to SPE, and a standard SPE was performed using C18-SPE columns. No derivatisation of the extracts was needed as in GC/MS analysis, and the LC run-time was 6.5min by gradient elution with a retention time of 2.4min. Linearity of calibration was obtained in the range between 0 and 500ng/ml (correlation coefficient R(2)=0.998). Using linear regression (0-50ng/ml) the limit of detection (LOD) was 2.0ng/ml and the limit of quantitation (LOQ) was 5.1ng/ml; day-to-day reproducibility and precision were tested at 15 and 250ng/ml and were 13.4ng/ml+/-3.3% and 255.8ng/ml+/-4.5%, respectively.

  20. Improved method for the determination of zinc pyrithione in environmental water samples incorporating on-line extraction and preconcentration coupled with liquid chromatography atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Bones, Jonathan; Thomas, Kevin V; Paull, Brett

    2006-11-03

    A method has been developed for the determination of zinc pyrithione (ZnPT) in environmental water samples using monolithic reversed-phase silica columns for rapid on-line large volume solid phase extraction in tandem with on-line matrix removal using sacrificial strong anion exchange (SAX) columns. This is coupled with reversed-phase liquid chromatography with atmospheric pressure chemical ionisation mass spectrometric detection. Limits of detection in spiked river water samples, using a 200 mL preconcentration volume, were determined as 18 ng L(-1), with a limit of quantitation of 62 ng L(-1). The percentage recovery from spiked river water was found to be 72+/-9 (n=3 extractions), whilst overall method precision, following 10 repeat complete analyses was found to be 27% RSD at 1 microg L(-1). Linearity was determined over the concentration range of 0.25-10 microg L(-1) and the calculated regression coefficient was R(2)=0.9802. The method was used to investigate the environmental fate of zinc pyrithione in waters and its partition coefficient between sediment and water phases.

  1. Retention of ionisable compounds on high-performance liquid chromatography. XV. Estimation of the pH variation of aqueous buffers with the change of the acetonitrile fraction of the mobile phase.

    PubMed

    Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

    2004-12-03

    The most commonly used mobile phases in reversed-phase high-performance liquid chromatography (RP-HPLC) are hydro-organic mixtures of an aqueous buffer and an organic modifier. The addition of this organic solvent to buffered aqueous solutions involves a variation of the buffer properties (pH and buffer capacity). In this paper, the pH variation is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-citrate, and ammonium-ammonia buffers. The proposed equations allow pH estimation of acetonitrile-water buffered mobile phases up to 60% (v/v) of organic modifier and initial aqueous buffer concentrations between 0.001 and 0.1 mol L(-1), from the initial aqueous pH. The estimated pH variation of the mobile phase and the pKa variation of the analytes allow us to predict the degree of ionisation of the analytes and from this and analyte hydrophobicities, to interpret the relative retention and separation of analyte mixtures.

  2. Determination of volatile N-nitrosamines in meat products by microwave-assisted extraction coupled with dispersive micro solid-phase extraction and gas chromatography--chemical ionisation mass spectrometry.

    PubMed

    Huang, Man-Chun; Chen, Hsin-Chang; Fu, Ssu-Chieh; Ding, Wang-Hsien

    2013-05-01

    A sensitive procedure, microwave-assisted extraction (MAE) coupled dispersive micro solid-phase extraction (D-μ-SPE), was developed to extract N-nitrosodimethylamine (NDMA) and other six volatile N-nitrosamines (NAms) from meat products. Parameters affecting the efficiency of MAE and D-μ-SPE were systematically investigated. For MAE, 5-g of a homogenised meat sample was extracted with 30 mL of a sodium hydroxide (0.025 M) solution at 100 °C for 10 min. The optimum D-μ-SPE conditions were immersing 100mg of Carboxen™ 1000 adsorbent in the MAE extract. After vigorously shaking for 30 min, the NAms were then desorbed by treatment with 200 μL of dichloromethane. A 10 μL aliquot was determined by gas chromatography with chemical ionisation mass spectrometry (GC-CI-MS) using the selected-ion-storage (SIS) mode. The limits of quantitation (LOQs) were 0.03-0.36 ng/g. Preliminary results revealed that NDMA was present in the highest concentration, ranging from 0.8 to 3.2 ng/g. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. The Insidious Nature of 'Hard-Core' Alternative Conceptions: Implications for the constructivist research programme of patterns in high school students' and pre-service teachers' thinking about ionisation energy

    NASA Astrophysics Data System (ADS)

    Taber, Keith S.; Tan, Kim Chwee Daniel

    2011-01-01

    The present study contributes to the constructivist research programme (RP) into learning science by comparing patterns in responses from two groups of learners-senior high school students and pre-service teachers-in the same educational context (Singapore), to a diagnostic instrument relating to the topic of ionisation energies. This topic is currently included in the curriculum for 16- to 19-year-old students studying chemistry in Singapore (and elsewhere). The comparison shows that: (1) although graduate pre-service teachers offered some types of incorrect responses less frequently than high school students; (2) they retained high levels of alternative conceptions commonly found among high school students; and (3) of particular note, certain alternative conceptions were found to be more common among the graduates. This suggests the intuitive appeal of certain alternative conceptions is such that they can readily be reproduced down 'generations' of learners. The findings are explored in terms of a range of conceptual resources that have been developed within the constructivist RP. The analysis suggests that the curriculum sets out inappropriate target knowledge for senior high school students, given the nature of the subject matter and the prior learning of the students. It is also suggested that it may be fruitful to consider conceptual learning in terms analogous to the RP found in science, and that from this perspective certain insidious alternative conceptions can be understood as derived from commitments that are taken for granted and protected from explicit challenge by a protective belt of refutable auxiliary conceptions.

  4. Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography-mass spectrometry with negative ion chemical ionisation.

    PubMed

    Albinet, A; Leoz-Garziandia, E; Budzinski, H; Viilenave, E

    2006-07-14

    This study deals with the development of a routine analytical method using gas chromatography-mass spectrometry with negative ion chemical ionisation (GC/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of this analytical procedure has been performed on standard reference material (SRM 1649a: urban dust), giving results in good agreement with the few data available in the literature. The analytical method was also applied on ambient air samples (on both gas and particulate phases) from the French POVA program (POllution des Vallées Alpines). NPAHs concentrations observed for a rural site during the Winter period are about 0.2-100.0pgm(-3) in the particulate phase and about 0.0-20.0pgm(-3) in the gas phase. OPAHs present concentrations 10-100 times higher (0.1-2.0ngm(-3) and 0.0-1.4ngm(-3) for the particulate and the gas phases, respectively). These preliminary results show a good correlation between the characteristics of the sampling site and the compound origins (primary or secondary).

  5. Identification of differentially expressed proteins of gamma-ray irradiated rat intestinal epithelial IEC-6 cells by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

    PubMed

    Bo, Zhang; Yongping, Su; Fengchao, Wang; Guoping, Ai; Yongjiang, Wei

    2005-02-01

    To identify proteins involved in the processes of cellular and molecular response to radiation damage repair in intestinal epithelial IEC-6 cells, we comparatively analyzed the proteome of irradiated IEC-6 cells with that of normal cells. A series of methods were used, including two-dimensional gel electrophoresis (Z-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and Swiss-Prot database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. Image analysis revealed that averages of 608 +/- 39 and 595 +/- 31 protein spots were detected in normal and irradiated IEC-6 cells, respectively. Sixteen differential protein spots were isolated from gels, and measured with MALDI-TOF-MS. A total of 14 spots yielded good spectra, and 11 spots matched with known proteins after database searching. These proteins were mainly involved in anti-oxidation, metabolism, and protein post-translational processes. Western blotting confirmed that stress-70 protein was down-regulated by gamma-irradiation. Up-regulation of ERP29 was confirmed by RT-PCR, indicating that it is involved in ionizing radiation. The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of radiation damage repair in intestinal epithelial cells.

  6. High-performance liquid chromatography with electrospray ionisation mass spectrometry and diode array detection in the identification and quantification of the degradation products of calix[4]arene crown-6 under radiolysis.

    PubMed

    Lamouroux, C; Aychet, N; Lelièvre, A; Jankowski, C K; Moulin, C

    2004-01-01

    The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO(3) 3 M) and an extreme exposure to radiolysis (10(6) Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions.

  7. Characterisation of ship diesel primary particulate matter at the molecular level by means of ultra-high-resolution mass spectrometry coupled to laser desorption ionisation--comparison of feed fuel, filter extracts and direct particle measurements.

    PubMed

    Rüger, Christopher P; Sklorz, Martin; Schwemer, Theo; Zimmermann, Ralf

    2015-08-01

    In this study, positive-mode laser desorption-ionisation ultra-high-resolution mass spectrometry (LDI-FT-ICR-MS) was applied to study combustion aerosol samples obtained from a ship diesel engine as well as the feed fuel, used to operate the engine. Furthermore, particulate matter was sampled from the exhaust tube using an impactor and analysed directly from the impaction foil without sample treatment. From the high percentage of shared sum formula as well as similarities in the chemical spread of aerosol and heavy fuel oil, results indicate that the primary aerosol mainly consists of survived, unburned species from the feed fuel. The effect of pyrosynthesis could be observed and was slightly more pronounced for the CH-class compared to other compound classes, but in summary not dominant. Alkylation pattern as well as the aromaticity distribution, using the double bond equivalent, revealed a shift towards lower alkylation state for the aerosol. The alkylation pattern of the most dominant series revealed a higher correlation between different aerosol samples than between aerosol and feed samples. This was confirmed by cluster analysis. Overall, this study shows that LDI-FT-ICR-MS can be successfully applied for the analysis of combustion aerosol at the molecular level and that sum formula information can be used to identify chemical differences between aerosol and fuel as well as between different size fractions of the particulate matter.

  8. Time-resolved analysis of the emission of sidestream smoke (SSS) from cigarettes during smoking by photo ionisation/time-of-flight mass spectrometry (PI-TOFMS): towards a better description of environmental tobacco smoke.

    PubMed

    Streibel, T; Mitschke, S; Adam, T; Zimmermann, R

    2013-09-01

    In this study, the chemical composition of sidestream smoke (SSS) emissions of cigarettes are characterised using a laser-based single-photon ionisation time-of-flight mass spectrometer. SSS is generated from various cigarette types (2R4F research cigarette; Burley, Oriental and Virginia single-tobacco-type cigarettes) smoked on a single-port smoking machine and collected using a so-called fishtail chimney device. Using this setup, a puff-resolved quantification of several SSS components was performed. Investigations of the dynamics of SSS emissions show that concentration profiles of various substances can be categorised into several groups, either depending on the occurrence of a puff or uninfluenced by the changes in the burning zone during puffing. The SSS emissions occurring directly after a puff strongly resemble the composition of mainstream smoke (MSS). In the smouldering phase, clear differences between MSS and SSS are observed. The changed chemical profiles of SSS and MSS might be also of importance on environmental tobacco smoke which is largely determined by SSS. Additionally, the chemical composition of the SSS is strongly affected by the tobacco type. Hence, the higher nitrogen content of Burley tobacco leads to the detection of increased amounts of nitrogen-containing substances in SSS.

  9. Characterisation by liquid chromatography coupled to electrospray ionisation ion trap mass spectrometry of phloroglucinol and 4-methylcatechol oxidation products to study the reactivity of epicatechin in an apple juice model system.

    PubMed

    Poupard, Pascal; Guyot, Sylvain; Bernillon, Stephane; Renard, Catherine M G C

    2008-02-01

    The reactivity of the (-)-epicatechin structure towards caffeoylquinic acid o-quinones was studied in an apple juice model solution. The approach consisted in considering separately the reactivities of the two phenolic moieties of an (-)-epicatechin molecule: phloroglucinol and 4-methylcatechol were chosen to represent A- and B-rings, respectively. The oxidation products were characterised by RP-HPLC coupled with electrospray ionisation Mass spectrometry (MS). The reactivities of the A- and B-rings were clearly different on the basis of the oxidation products formed. Both A- and B-rings could be involved in covalent bond formation, but electron transfers only occurred with the B-ring. Most of the (-)-epicatechin oxidation products were linked by A/B-ring linkage ("head-to-tail" intermolecular coupling). After this first dimerisation step, intramolecular reactions seemed to be favoured. Therefore, the complexity of oxidation products in apple juice does not only result from an extensive polymerisation of native phenolic compounds, but also from a multiplicity of small molecules in different oxidation states and isomeric forms.

  10. Supersonic molecular beam-hyperthermal surface ionisation coupled with time-of-flight mass spectrometry applied to trace level detection of polynuclear aromatic hydrocarbons in drinking water for reduced sample preparation and analysis time.

    PubMed

    Davis, S C; Makarov, A A; Hughes, J D

    1999-01-01

    Analysis of sub-ppb levels of polynuclear aromatic hydrocarbons (PAHs) in drinking water by high performance liquid chromatography (HPLC) fluorescence detection typically requires large water samples and lengthy extraction procedures. The detection itself, although selective, does not give compound identity confirmation. Benchtop gas chromatography/mass spectrometry (GC/MS) systems operating in the more sensitive selected ion monitoring (SIM) acquisition mode discard spectral information and, when operating in scanning mode, are less sensitive and scan too slowly. The selectivity of hyperthermal surface ionisation (HSI), the high column flow rate capacity of the supersonic molecular beam (SMB) GC/MS interface, and the high acquisition rate of time-of-flight (TOF) mass analysis, are combined here to facilitate a rapid, specific and sensitive technique for the analysis of trace levels of PAHs in water. This work reports the advantages gained by using the GC/HSI-TOF system over the HPLC fluorescence method, and discusses in some detail the nature of the instrumentation used.

  11. Dissociation of biomolecules using a ultraviolet matrix-assisted laser desorption/ionisation time-of-flight/curved field reflectron tandem mass spectrometer equipped with a differential-pumped collision cell.

    PubMed

    Belgacem, Omar; Bowdler, Andrew; Brookhouse, Ian; Brancia, Francesco L; Raptakis, Emmanuel

    2006-01-01

    A commercial matrix-assisted laser desorption/ionisation time-of-flight (MALDI-ToF) instrument equipped with a curved field reflectron (CFR) was modified in order to perform collision-induced dissociation (CID) on a variety of biomolecules. The incorporation of a high-resolution ion gate together with a collision cell within the field-free region allowed tandem mass analysis (MS/MS), without the necessity to decelerate the precursor ions prior to activation. The simultaneous detection of all product ions remained possible by using the CFR. To test the MS/MS performances, ACTH (fragment 1-17), a complex high mannose carbohydrate (Man)(8)(GlcNac)(2) and a lysophosphatidylcholine lipid (18:1) were analysed on the modified instrument. Direct comparison with the low-energy product ion spectra, acquired on a MALDI quadrupole ion trap (QIT) two-stage reflectron time-of flight (ReToF) mass spectrometer, showed significant differences in the types of product ions observed. The additional ions detected were a clear indication of the high-energy fragmentation processes occurring in the collision cell.

  12. Bladder cancer.

    PubMed Central

    Leung, H. Y.; Griffiths, T. R.; Neal, D. E.

    1996-01-01

    Bladder cancer is the fourth most common cancer in England and Wales. The most common presenting symptom is macroscopic haematuria. The management options for superficial and invasive bladder cancer depend on the stage at presentation. Most superficial bladder cancers are managed by transurethral resection and cytoscopic follow-up. The prognosis for patients with invasive bladder cancer is less good. The role of chemical, radiotherapeutic and surgical intervention are discussed. PMID:9015464

  13. Chemical mapping of the colorectal cancer microenvironment via MALDI imaging mass spectrometry (MALDI-MSI) reveals novel cancer-associated field effects.

    PubMed

    Mirnezami, R; Spagou, K; Vorkas, P A; Lewis, M R; Kinross, J; Want, E; Shion, H; Goldin, R D; Darzi, A; Takats, Z; Holmes, E; Cloarec, O; Nicholson, J K

    2014-02-01

    Matrix-assisted laser desorption ionisation imaging mass spectrometry (MALDI-MSI) is a rapidly advancing technique for intact tissue analysis that allows simultaneous localisation and quantification of biomolecules in different histological regions of interest. This approach can potentially offer novel insights into tumour microenvironmental (TME) biochemistry. In this study we employed MALDI-MSI to evaluate fresh frozen sections of colorectal cancer (CRC) tissue and adjacent healthy mucosa obtained from 12 consenting patients undergoing surgery for confirmed CRC. Specifically, we sought to address three objectives: (1) To identify biochemical differences between different morphological regions within the CRC TME; (2) To characterise the biochemical differences between cancerous and healthy colorectal tissue using MALDI-MSI; (3) To determine whether MALDI-MSI profiling of tumour-adjacent tissue can identify novel metabolic 'field effects' associated with cancer. Our results demonstrate that CRC tissue harbours characteristic phospholipid signatures compared with healthy tissue and additionally, different tissue regions within the CRC TME reveal distinct biochemical profiles. Furthermore we observed biochemical differences between tumour-adjacent and tumour-remote healthy mucosa. We have referred to this 'field effect', exhibited by the tumour locale, as cancer-adjacent metaboplasia (CAM) and this finding builds on the established concept of field cancerisation. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  14. Cell injury, retrodifferentiation and the cancer treatment paradox.

    PubMed

    Uriel, José

    2015-09-01

    This "opinion article" is an attempt to take an overview of some significant changes that have happened in our understanding of cancer status during the last half century and its evolution under the progressive influence of molecular biology. As an active worker in cancer research and developmental biology during most of this period, I would like to comment briefly on these changes and to give my critical appreciation of their outcome as it affects our knowledge of cancer development as well as the current treatment of the disease. A recall of my own contribution to the subject is also included. Two subjects are particularly developed: cell injury and cell-killing therapies. Cell injury, whatever its origin, has acquired the status of a pivotal event for the initiation of cancer emergence. It is postulated that cell injury, a potential case of cellular death, may also be the origin of a process of stepwise cell reversion (retrodifferentiation or retroprogrammation) leading, by division, mature or stem cells to progressive immaturity. The genetic instability and mutational changes that accompanies this process of cell injury and rejuvenation put normal cells in a status favourable to neoplastic transformation or may evolve cancer cells toward clones with higher malignant potentiality. Thus, cell injury suggests lifestyle as the major upstream initiator of cancer development although this not exclude randomness as an unavoidable contributor to the disease. Cell-killing agents (mainly cytotoxic drugs and radiotherapy) are currently used to treat cancer. At the same time, it is agreed that agents with high cell injury potential (ultraviolet light, ionising radiations, tobacco, environmental pollutants, etc.) contribute to the emergence of malignant tumours. This represents a real paradox. In spite of the progress accomplished in cancer survival, one is tempted to suggest that we have very few chances of really cure cancer as long as we continue to treat malignancies

  15. A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

    NASA Astrophysics Data System (ADS)

    Gill, Martin R.; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A.; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A.

    2016-08-01

    Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

  16. A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

    PubMed Central

    Gill, Martin R.; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A.; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A.

    2016-01-01

    Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing. PMID:27558808

  17. Medical exposure to radiation and thyroid cancer.

    PubMed

    Schonfeld, S J; Lee, C; Berrington de González, A

    2011-05-01

    In 2008, the worldwide estimated age-standardised incidence rates for thyroid cancer incidence were 4.7 and 1.5 per 100,000 women and men, respectively. Thyroid cancer's overall contribution to the worldwide cancer burden is relatively small, but incidence rates have increased over the last three decades throughout the world. This trend has been hypothesised to reflect a combination of technological advances enabling increased detection, but also changes in environmental factors, including population exposure to ionising radiation from fallout, diagnostic tests and treatment for benign and malignant conditions. Studies of the atomic bomb survivors and populations treated with radiotherapy have established radiation as a risk factor for thyroid cancer, particularly from early life exposure. About 0.62 mSv (20%) of the global annual per caput effective radiation dose comes from diagnostic medical and dental radiation for the period of 1997-2007, increased from 0.4 mSv for the years 1991-1996. This international trend of increasing population exposure to medical diagnostic sources of radiation, attributed in large part to the growing use of computed tomography scans, but also interventional radiology procedures, has raised concerns about exposure to radiosensitive organs such as the thyroid. Worldwide, medical and dental X-rays constitute the most common type of diagnostic medical exposures, but their contribution to the cumulative effective dose is relatively low, whereas computed tomography scans account for 7.9% of diagnostic radiology examinations but 47% of the collective effective dose from diagnostic radiation procedures in parts of the world. Although the radiation exposure from computed tomography scans is substantially lower than that from radiotherapy, multiple computed tomography scans could result in non-trivial cumulative doses to the thyroid. Studies are currently underway to assess the incidence of cancer in large cohorts of children who received

  18. [Ionizing radiation as a risk factor for thyroid cancer in Krakow and Nowy Sacz regions].

    PubMed

    Szybiński, Z; Olko, P; Przybylik-Mazurek, E; Burzyński, M

    2001-01-01

    In a group of 224 patients with thyroid cancer registered from 1990 to 1999 and in 243 controls matched for sex and age doses for the thyroid due to accumulation of 131I after Chernobyl accident and radiological diagnostic procedures involving the neck and dentition was calculated according to Johnson's model and based upon questionnaires. There was a significantly higher dose for the thyroid due to accumulation of 131I in the Krakow area in comparison with the Nowy Sacz area. There was also a significantly higher frequency of radiological procedures involving the thyroid gland preceding the development of thyroid cancer in comparison with the control group. The present findings are concordant with about 40% increase of thyroid cancer in the Krakow area in comparison with the Nowy Sacz region. The present study has indicated that ionising radiation may be a factor involved in the pathogenesis of thyroid cancer and its significant rise within the last 10 years. However, it has not been the main factor, but only one of the risk factors. The study has also indicated that iodine prophylaxis should be continued and that radiological procedures involving the neck and head in patients with nodular goitre should be carried out with caution.

  19. IGF-1R associates with adverse outcomes after radical radiotherapy for prostate cancer.

    PubMed

    Aleksic, Tamara; Verrill, Clare; Bryant, Richard J; Han, Cheng; Worrall, Andrew Ross; Brureau, Laurent; Larré, Stephane; Higgins, Geoff S; Fazal, Fahad; Sabbagh, Ahmad; Haider, Syed; Buffa, Francesca M; Cole, David; Macaulay, Valentine M

    2017-10-03

    Activated type 1 insulin-like growth factor receptors (IGF-1Rs) undergo internalisation and nuclear translocation, promoting cell survival. We previously reported that IGF-1R inhibition delays DNA damage repair, sensitising prostate cancer cells to ionising radiation. Here we tested the clinical relevance of these findings. We assessed associations between IGF-1R and clinical outcomes by immunohistochemistry in diagnostic biopsies of 136 men treated with 55-70 Gy external beam radiotherapy for prostate cancer, comparing results with publicly available transcriptional data in surgically treated patients. Following radiotherapy, overall recurrence-free survival was shorter in patients whose tumours contained high total, cytoplasmic and internalised (nuclear/cytoplasmic) IGF-1R. High total IGF-1R associated with high primary Gleason grade and risk of metastasis, and cytoplasmic and internalised IGF-1R with biochemical recurrence, which includes patients experiencing local recurrence within the radiation field indicating radioresistance. In multivariate analysis, cytoplasmic, internalised and total IGF-1R were independently associated with risk of overall recurrence, and cytoplasmic IGF-1R was an independent predictor of biochemical recurrence post radiotherapy. Insulin-like growth factor receptors expression did not associate with biochemical recurrence after radical prostatectomy. These data reveal increased risk of post-radiotherapy recurrence in men whose prostate cancers contain high levels of total or cytoplasmic IGF-1R.British Journal of Cancer advance online publication: 3 October 2017; doi:10.1038/bjc.2017.337 www.bjcancer.com.

  20. Mitigating the risk of radiation-induced cancers: limitations and paradigms in drug development.

    PubMed

    Yoo, Stephen S; Jorgensen, Timothy J; Kennedy, Ann R; Boice, John D; Shapiro, Alla; Hu, Tom C-C; Moyer, Brian R; Grace, Marcy B; Kelloff, Gary J; Fenech, Michael; Prasanna, Pataje G S; Coleman, C Norman

    2014-06-01

    The United States radiation medical countermeasures (MCM) programme for radiological and nuclear incidents has been focusing on developing mitigators for the acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE), and biodosimetry technologies to provide radiation dose assessments for guiding treatment. Because a nuclear accident or terrorist incident could potentially expose a large number of people to low to moderate doses of ionising radiation, and thus increase their excess lifetime cancer risk, there is an interest in developing mitigators for this purpose. This article discusses the current status, issues, and challenges regarding development of mitigators against radiation-induced cancers. The challenges of developing mitigators for ARS include: the long latency between exposure and cancer manifestation, limitations of animal models, potential side effects of the mitigator itself, potential need for long-term use, the complexity of human trials to demonstrate effectiveness, and statistical power constraints for measuring health risks (and reduction of health risks after mitigation) following relatively low radiation doses (<0.75 Gy). Nevertheless, progress in the understanding of the molecular mechanisms resulting in radiation injury, along with parallel progress in dose assessment technologies, make this an opportune, if not critical, time to invest in research strategies that result in the development of agents to lower the risk of radiation-induced cancers for populations that survive a significant radiation exposure incident.