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Sample records for fluidity determines sensitivity

  1. Factors determining Staphylococcus aureus susceptibility to photoantimicrobial chemotherapy: RsbU activity, staphyloxanthin level and membrane fluidity.

    Directory of Open Access Journals (Sweden)

    Monika Kossakowska-Zwierucho

    2016-07-01

    Full Text Available Photoantimicrobial chemotherapy (PACT constitutes a particular type of stress condition, in which bacterial cells induce a pleiotropic and as yet unexplored effect. In light of this, the key master regulators are of putative significance to the overall phototoxic outcome. In Staphylococcus aureus, the alternative sigma factor σB controls the expression of genes involved in the response to environmental stress. We show that aberration of any sigB operon genes in S. aureus USA300 isogenic mutants causes a pronounced sensitization (>5 log10 reduction in CFU drop to PACT with selected photosensitizers, namely protoporphyrin diarginate, zinc phthalocyanine and rose bengal. This effect is partly due to aberration-coupled staphyloxanthin synthesis inhibition. We identified frequent mutations in RsbU, a σB activator, in PACT-vulnerable clinical isolates of S. aureus, resulting in σB activity impairment. Locations of significant changes in protein structure (IS256 insertion, early STOP codon occurrence, substitutions A230T and A276D were shown in a theoretical model of S. aureus RsbU. As a phenotypic hallmark of PACT-vulnerable S. aureus strains, we observed an increased fluidity of bacterial cell membrane, which is a result of staphyloxanthin content and other yet unidentified factors. Our research indicates σB as a promising target of adjunctive antimicrobial therapy and suggests that enhanced cell membrane fluidity may be an adjuvant strategy in photoantimicrobial chemotherapy.

  2. Correlation between membrane fluidity cellular development and stem cell differentiation

    KAUST Repository

    Noutsi, Pakiza

    2016-12-01

    Cell membranes are made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as neuronal differentiation, cell membranes undergo dramatic structural changes induced by proteins such as ARC and Cofilin among others in the case of synaptic modification. In this study we used the generalized polarization (GP) property of fluorescent probe Laurdan using two-photon microscopy to determine membrane fluidity as a function of time and for various cell lines. A low GP value corresponds to a higher fluidity and a higher GP value is associated with a more rigid membrane. Four different cell lines were monitored such as hN2, NIH3T3, HEK293 and L6 cells. As expected, NIH3T3 cells have more rigid membrane at earlier stages of their development. On the other hand neurons tend to have the highest membrane fluidity early in their development emphasizing its correlation with plasticity and the need for this malleability during differentiation. This study sheds light on the involvement of membrane fluidity during neuronal differentiation and development of other cell lines.

  3. Fluidity of pea root plasma membranes under altered gravity

    Science.gov (United States)

    Klymchuk, D. O.; Baranenko, V. V.; Vorobyova, T. V.; Dubovoy, V. D.

    This investigation aims to determine whether clinorotation 2 rev min of pea Pisum sativum L seedlings induces the alterations in the physical-chemical properties of cellular membranes including the plasma membrane fluidity The last is an important regulator of functional activity of membrane enzymes The plasma membranes were isolated by aqueous two-phase partitioning from roots of 6-day old pea seedlings The membrane fluidity was examined by fluorescence spectroscopy using pyrene probe The plasma membrane vesicles with known protein concentration were added to the incubation buffer to a final concentration of 50 mu g of protein per ml A small amount by 1 mu l of pyrene solution in 2-propanol was added to the incubation mixture to a final probe concentration 5 mu M at constant mixing Fluorescence spectra were measured using a Perkin-Elmer LS-50 spectrofluorometer Perkin-Elmer England Pyrene was excited at 337 nm and fluorescence intensity of monomers I M and excimers I E were measured at 393 and 470 nm respectively The I E I M ratios were 0 081 pm 0 003 and 0 072 pm 0 004 in preparations obtained from clinorotated and the control seedlings respectively This fact indicates that rotation on the clinostat increases the membrane fluidity Compared with controls clinorotated seedlings have also showed a reduced growth and a higher level of total unsaturated fatty acids determined by gas chromatography The factors that influence on the fluidity of membrane lipids in bilayer appear to be the

  4. Fluidity in the networked society

    DEFF Research Database (Denmark)

    Levinsen, Karin Tweddell

    2011-01-01

    In the globalized economies e-permeation has become a basic condition in our everyday lives. ICT can no longer be understood solely as artefacts and tools and computer-related literacy are no longer restricted to the ability to operate digital tools for specific purposes. The network society......, and therefore also eLearning are characterized by fluidity and the key competence for social actors in this ever changing e-permeated environment is the ability to cope with change - or Castells’ conceptualisation self-programming. Castells’ theory has influenced international definitions of future key...... competencies. Both lifelong learning and digital literacy understood as "bildung" have emerged as central for the definitions of and standards for future key competencies. However, definitions and standards only tell us about the desired destination and outcome of digital competence building. They tell us...

  5. Self-powered detectors sensitivity determination

    International Nuclear Information System (INIS)

    Surkov, V.; Soares, A.J.

    1994-01-01

    The determination of the initial sensitivity of Self Powered Detectors (SPDs) was performed. Measurements of thermal, epithermal and to gamma flux sensitivities were made with Vanadium, Cobalt, Rhodium, Silver and Platinum SPDs and, when possible, the values are compared with the ones from the existing literature. The determination of neutron sensitivity was realized using the IEA-R1 Reactor from IPEN. The thermal and epithermal neutron flux were determined with bare and Cadmium covered activation foils. (GOLD). (author)

  6. Assessment of Membrane Fluidity Fluctuations during Cellular Development Reveals Time and Cell Type Specificity

    KAUST Repository

    Noutsi, Bakiza Kamal; Gratton, Enrico; Chaieb, Saharoui

    2016-01-01

    Cell membrane is made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as differentiation cell membranes undergo dramatic fluidity changes induced by proteins such as ARC and Cofilin among others. In this study we used the generalized polarization (GP) property of fluorescent probe Laurdan using two-photon microscopy to determine membrane fluidity as a function of time and for various cell lines. A low GP value corresponds to a higher fluidity and a higher GP value is associated with a more rigid membrane. Four different cell lines were monitored such as hN2, NIH3T3, HEK293 and L6 cells. Membrane fluidity was measured at 12h, 72h and 92 h. Our results show significant changes in membrane fluidity among all cell types at different time points. GP values tend to increase significantly within 92 h in hN2 cells and 72 h in NIH3T3 cells and only at 92 h in HEK293 cells. L6 showed a marked decrease in membrane fluidity at 72 h and starts to increase at 92 h. As expected, NIH3T3 cells have more rigid membrane at earlier time points. On the other hand, neurons tend to have the highest membrane fluidity at early time points emphasizing its correlation with plasticity and the need for this malleability during differentiation. This study sheds light on the involvement of membrane fluidity during neuronal differentiation and development of other cell lines.

  7. Assessment of Membrane Fluidity Fluctuations during Cellular Development Reveals Time and Cell Type Specificity

    KAUST Repository

    Noutsi, Bakiza Kamal

    2016-06-30

    Cell membrane is made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as differentiation cell membranes undergo dramatic fluidity changes induced by proteins such as ARC and Cofilin among others. In this study we used the generalized polarization (GP) property of fluorescent probe Laurdan using two-photon microscopy to determine membrane fluidity as a function of time and for various cell lines. A low GP value corresponds to a higher fluidity and a higher GP value is associated with a more rigid membrane. Four different cell lines were monitored such as hN2, NIH3T3, HEK293 and L6 cells. Membrane fluidity was measured at 12h, 72h and 92 h. Our results show significant changes in membrane fluidity among all cell types at different time points. GP values tend to increase significantly within 92 h in hN2 cells and 72 h in NIH3T3 cells and only at 92 h in HEK293 cells. L6 showed a marked decrease in membrane fluidity at 72 h and starts to increase at 92 h. As expected, NIH3T3 cells have more rigid membrane at earlier time points. On the other hand, neurons tend to have the highest membrane fluidity at early time points emphasizing its correlation with plasticity and the need for this malleability during differentiation. This study sheds light on the involvement of membrane fluidity during neuronal differentiation and development of other cell lines.

  8. Membrane fluidity and the radiosensitivity of E. coli K1060

    International Nuclear Information System (INIS)

    Alper, T.; Cramp, W.A.; George, A.; Lunec, J.

    1981-01-01

    Escherichia coli K1060 is deficient in ability to synthesize unsaturated fatty acids, so that the composition of the membrane, and therefore its fluidity, can be changed. A discussion is presented of the results of George et al (1980) concerning the relation of radiosensitivity to membrane fluidity. The following speculations are made: 1) At ice temperatures the membrane of oleic grown bacteria is in the 'gel' state, whereas in elaidic grown bacteria the membrane is in an even more rigid configuration. As a result, lesions produced during irradiation in the presence of oxygen are more lethal than in the more fluid conditions prevailing at room temperature. 2) At room temperature it may be that the bacteria are conditioned by pre-irradiation anoxia so that they become more able to repair damage. When the temperature is decreased to ice levels in bacteria modified by growth in oleic and elaidic acid, reduced membrane fluidity may impair the metabolic activity required for this pre-irradiation conditioning. 3) The lack of temperature effects with the linoleic grown bacteria, that is, no sensitization under aerated conditions and no loss in shoulder under anoxic conditions, is consistent with the lower membrane transitions temperature (fluid to gel) associated with this fatty acid. (U.K.)

  9. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Science.gov (United States)

    Sonmez, Melda; Ince, Huseyin Yavuz; Yalcin, Ozlem; Ajdžanović, Vladimir; Spasojević, Ivan; Meiselman, Herbert J; Baskurt, Oguz K

    2013-01-01

    The role of membrane fluidity in determining red blood cell (RBC) deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol) using ektacytometry and electron paramagnetic resonance (EPR) spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease) and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; palcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology) was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  10. Subcellular membrane fluidity of Lactobacillus delbrueckii subsp. bulgaricus under cold and osmotic stress.

    Science.gov (United States)

    Meneghel, Julie; Passot, Stéphanie; Cenard, Stéphanie; Réfrégiers, Matthieu; Jamme, Frédéric; Fonseca, Fernanda

    2017-09-01

    Cryopreservation of lactic acid bacteria may lead to undesirable cell death and functionality losses. The membrane is the first target for cell injury and plays a key role in bacterial cryotolerance. This work aimed at investigating at a subcellular resolution the membrane fluidity of two populations of Lactobacillus delbrueckii subsp. bulgaricus when subjected to cold and osmotic stresses associated to freezing. Cells were cultivated at 42 °C in mild whey medium, and they were exposed to sucrose solutions of different osmolarities (300 and 1800 mOsm L -1 ) after harvest. Synchrotron fluorescence microscopy was used to measure membrane fluidity of cells labeled with the cytoplasmic membrane probe 1-[4 (trimethylamino) phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH). Images were acquired at 25 and 0 °C, and more than a thousand cells were individually analyzed. Results revealed that a bacterial population characterized by high membrane fluidity and a homogeneous distribution of fluidity values appeared to be positively related to freeze-thaw resistance. Furthermore, rigid domains with different anisotropy values were observed and the occurrence of these domains was more important in the freeze-sensitive bacterial population. The freeze-sensitive cells exhibited a broadening of existing highly rigid lipid domains with osmotic stress. The enlargement of domains might be ascribed to the interaction of sucrose with membrane phospholipids, leading to membrane disorganization and cell degradation.

  11. Reorganization of Azospirillum brasilense cell membrane is mediated by lipid composition adjustment to maintain optimal fluidity during water deficit.

    Science.gov (United States)

    Cesari, A B; Paulucci, N S; Biasutti, M A; Reguera, Y B; Gallarato, L A; Kilmurray, C; Dardanelli, M S

    2016-01-01

    We study the Azospirillum brasilense tolerance to water deficit and the dynamics of adaptive process at the level of the membrane. Azospirillum brasilense was exposed to polyethylene glycol (PEG) growth and PEG shock. Tolerance, phospholipids and fatty acid (FA) composition and membrane fluidity were determined. Azospirillum brasilense was able to grow in the presence of PEG; however, its viability was reduced. Cells grown with PEG showed membrane fluidity similar to those grown without, the lipid composition was modified, increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FAs degree was reduced. The dynamics of the adaptive response revealed a decrease in fluidity 20 min after the addition of PEG, indicating that the PEG has a fluidizing effect on the hydrophobic region of the cell membrane. Fluidity returned to initial values after 60 min of PEG exposure. Azospirillum brasilense is able to perceive osmotic changes by changing the membrane fluidity. This effect is offset by changes in the composition of membrane phospholipid and FA, contributing to the homeostasis of membrane fluidity under water deficit. This knowledge can be used to develop new Azospirillum brasilense formulations showing an adapted membrane to water deficit. © 2015 The Society for Applied Microbiology.

  12. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Directory of Open Access Journals (Sweden)

    Melda Sonmez

    Full Text Available The role of membrane fluidity in determining red blood cell (RBC deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol using ektacytometry and electron paramagnetic resonance (EPR spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01. The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  13. [Fluorescence polarization used to investigate the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field].

    Science.gov (United States)

    Zhang, Ying; Zeng, Xin-An; Wen, Qi-Biao; Li, Lin

    2008-01-01

    To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.

  14. Correlation between ionic conductivity and fluidity of polymer gel ...

    Indian Academy of Sciences (India)

    Unknown

    Ionic conductivity; ion aggregates; FTIR spectroscopy; gels; fluidity. 1. Introduction ... liquid and polymer gel electrolytes have been studied as functions of salt ..... Ratner M A 1987 in Polymer electrolyte reviews (eds) J R. MacCallum and C A ...

  15. Correlation between membrane fluidity cellular development and stem cell differentiation

    KAUST Repository

    Noutsi, Bakiza Kamal

    2016-01-01

    Cell membranes are made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as neuronal differentiation, cell membranes undergo dramatic structural

  16. Tax aggressiveness and corporate social responsibility fluidity in ...

    African Journals Online (AJOL)

    Tax aggressiveness and corporate social responsibility fluidity in Nigerian firms. ... the nexus between shareholding and wider-spectrum stake-holding, where key ... to forge mutually expedient cash flow mechanisms for sustainable corporate ...

  17. Possible evolutionary origins of human female sexual fluidity.

    Science.gov (United States)

    Kanazawa, Satoshi

    2017-08-01

    I propose an evolutionary theory of human female sexual fluidity and argue that women may have been evolutionarily designed to be sexually fluid in order to allow them to have sex with their cowives in polygynous marriage and thus reduce conflict and tension inherent in such marriage. In addition to providing an extensive definition and operationalization of the concept of sexual fluidity and specifying its ultimate function for women, the proposed theory can potentially solve several theoretical and empirical puzzles in evolutionary psychology and sex research. Analyses of the National Longitudinal Study of Adolescent Health (Add Health) confirm the theory's predictions that: (i) women (but not men) who experience increased levels of sexual fluidity have a larger number of children (suggesting that female sexual fluidity, if heritable, may be evolutionarily selected); (ii) women (but not men) who experience marriage or parenthood early in adult life subsequently experience increased levels of sexual fluidity; and (iii) sexual fluidity is significantly positively correlated with known markers of unrestricted sexual orientation among women whereas it is significantly negatively correlated with such markers among men. © 2016 Cambridge Philosophical Society.

  18. Tolerance to chitosan by Trichoderma species is associated with low membrane fluidity.

    Science.gov (United States)

    Zavala-González, Ernesto A; Lopez-Moya, Federico; Aranda-Martinez, Almudena; Cruz-Valerio, Mayra; Lopez-Llorca, Luis Vicente; Ramírez-Lepe, Mario

    2016-07-01

    The effect of chitosan on growth of Trichoderma spp., a cosmopolitan genus widely exploited for their biocontrol properties was evaluated. Based on genotypic (ITS of 18S rDNA) characters, four isolates of Trichoderma were identified as T. pseudokoningii FLM16, T. citrinoviride FLM17, T. harzianum EZG47, and T. koningiopsis VSL185. Chitosan reduces radial growth of Trichoderma isolates in concentration-wise manner. T. koningiopsis VSL185 was the most chitosan tolerant isolate in all culture media amended with chitosan (0.5-2.0 mg ml(-1) ). Minimal Inhibitory Concentration (MIC) and Minimal Fungicidal Concentration (MFC) were determined showing that T. koningiopsis VSL185 displays higher chitosan tolerance with MIC value >2000 μg ml(-1) while for other Trichoderma isolates MIC values were around 10 μg ml(-1) . Finally, free fatty acid composition reveals that T. koningiopsis VSL185, chitosan tolerant isolate, displays lower linolenic acid (C18:3) content than chitosan sensitive Trichoderma isolates. Our findings suggest that low membrane fluidity is associated with chitosan tolerance in Trichoderma spp. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Assessment and optimization of thermal and fluidity properties of high strength concrete via genetic algorithm

    Directory of Open Access Journals (Sweden)

    Barış Şimşek

    2016-12-01

    Full Text Available This paper proposes a Response Surface Methodology (RSM based Genetic Algorithm (GA using MATLAB® to assess and optimize the thermal and fluidity of high strength concrete (HSC. The overall heat transfer coefficient, slump-spread flow and T50 time was defined as thermal and fluidity properties of high strength concrete. In addition to above mentioned properties, a 28-day compressive strength of HSC was also determined. Water to binder ratio, fine aggregate to total aggregate ratio and the percentage of super-plasticizer content was determined as effective factors on thermal and fluidity properties of HSC. GA based multi-objective optimization method was carried out by obtaining quadratic models using RSM. Having excessive or low ratio of water to binder provides lower overall heat transfer coefficient. Moreover, T50 time of high strength concrete decreased with the increasing of water to binder ratio and the percentage of superplasticizer content. Results show that RSM based GA is effective in determining optimal mixture ratios of HSC.

  20. Hydrostatic pressure decreases membrane fluidity and lipid desaturase expression in chondrocyte progenitor cells.

    Science.gov (United States)

    Montagne, Kevin; Uchiyama, Hiroki; Furukawa, Katsuko S; Ushida, Takashi

    2014-01-22

    Membrane biomechanical properties are critical in modulating nutrient and metabolite exchange as well as signal transduction. Biological membranes are predominantly composed of lipids, cholesterol and proteins, and their fluidity is tightly regulated by cholesterol and lipid desaturases. To determine whether such membrane fluidity regulation occurred in mammalian cells under pressure, we investigated the effects of pressure on membrane lipid order of mouse chondrogenic ATDC5 cells and desaturase gene expression. Hydrostatic pressure linearly increased membrane lipid packing and simultaneously repressed lipid desaturase gene expression. We also showed that cholesterol mimicked and cholesterol depletion reversed those effects, suggesting that desaturase gene expression was controlled by the membrane physical state itself. This study demonstrates a new effect of hydrostatic pressure on mammalian cells and may help to identify the molecular mechanisms involved in hydrostatic pressure sensing in chondrocytes. © 2013 Elsevier Ltd. All rights reserved.

  1. Noninvasive determination of optical lever sensitivity in atomic force microscopy

    International Nuclear Information System (INIS)

    Higgins, M.J.; Proksch, R.; Sader, J.E.; Polcik, M.; Mc Endoo, S.; Cleveland, J.P.; Jarvis, S.P.

    2006-01-01

    Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity

  2. Noninvasive determination of optical lever sensitivity in atomic force microscopy

    Science.gov (United States)

    Higgins, M. J.; Proksch, R.; Sader, J. E.; Polcik, M.; Mc Endoo, S.; Cleveland, J. P.; Jarvis, S. P.

    2006-01-01

    Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity.

  3. Beyond Alphabet Soup: Helping College Health Professionals Understand Sexual Fluidity

    Science.gov (United States)

    Oswalt, Sara B.; Evans, Samantha; Drott, Andrea

    2016-01-01

    Many college students today are no longer using the terms straight, gay, lesbian, bisexual, or transgender to self-identify their sexual orientation or gender identity. This commentary explores research related to fluidity of sexual identities, emerging sexual identities used by college students, and how these identities interact with the health…

  4. Shear viscosity and imperfect fluidity in bosonic and fermionic superfluids

    Science.gov (United States)

    Boyack, Rufus; Guo, Hao; Levin, K.

    2014-12-01

    In this paper we address the ratio of the shear viscosity to entropy density η /s in bosonic and fermionic superfluids. A small η /s is associated with nearly perfect fluidity, and more general measures of the fluidity perfection/imperfection are of wide interest to a number of communities. We use a Kubo approach to concretely address this ratio via low-temperature transport associated with the quasiparticles. Our analysis for bosonic superfluids utilizes the framework of the one-loop Bogoliubov approximation, whereas for fermionic superfluids we apply BCS theory and its BCS-BEC extension. Interestingly, we find that the transport properties of strict BCS and Bogoliubov superfluids have very similar structures, albeit with different quasiparticle dispersion relations. While there is a dramatic contrast between the power law and exponential temperature dependence for η alone, the ratio η /s for both systems is more similar. Specifically, we find the same linear dependence (on the ratio of temperature T to inverse lifetime γ (T ) ) with η /s ∝T /γ (T ) , corresponding to imperfect fluidity. By contrast, near the unitary limit of BCS-BEC superfluids a very different behavior results, which is more consistent with near-perfect fluidity.

  5. Vibration improved the fluidity of aluminum alloys in thin wall ...

    African Journals Online (AJOL)

    user

    The technique to "increase" the metal head during casting and improve the ... The effect of vibration is quantified and incorporated into the fluidity model, such that the ..... Deformation, caused by the expansion and contraction of the thin skin of ...

  6. Sensitivity determination of CR-39 from Normal and inclined incidence

    International Nuclear Information System (INIS)

    Abou, A.A.; El-Kheir, A.A.; Daas, A.F.; Awwad, Z.; Reda, A.M.

    2000-01-01

    An experimental study have been carried out on alpha- particle track opening (Major and minor axes) using alpha-particles of different energies incident with different angels in addition to the normal incidence. The sensitivity of CR-39 in present work is determined for each of normal and inclined incidence. The results indicated a difference in the sensitivity according to angle of incidence. The variation of alpha- particle tracks (major and minor axes) are calculated and compared with our measured values. Also, it is found that the sensitivity of CR-39 detector is change due to the storage time at room temperature

  7. Sensitivity and specificity of copper sulphate test in determining ...

    African Journals Online (AJOL)

    Background: The accuracy of the copper sulphate method for the rapid screening of prospective blood donors has been questioned because this rapid screening method may lead to false deferral of truly eligible prospective blood donors. Objective: This study was aimed at determining the sensitivity and specificity of copper ...

  8. Gender fluidity and child abuse: A personal view.

    Science.gov (United States)

    Lewis, Charles

    2017-12-01

    Gender fluidity and a failure to respect biological norms may have potentially horrific implications for children and adolescents who express doubt about their bodies. Are transgender activists driving an agenda that will result in inappropriate interventions that block normal development in children and adolescents from which there can be no return? Can the Law protect children and adolescents from harm committed with the intention of helping them?

  9. Influence of membrane fatty acid composition and fluidity on airborne survival of Escherichia coli.

    Science.gov (United States)

    Ng, Tsz Wai; Chan, Wing Lam; Lai, Ka Man

    2018-04-01

    Finding ways to predict and control the survival of bacterial aerosols can contribute to the development of ways to alleviate a number of crucial microbiological problems. Significant damage in the membrane integrity of Escherichia coli during aerosolization and airborne suspension has been revealed which has prompted the question of how the membrane fatty acid composition and fluidity influence the survival of airborne bacteria. Two approaches of using isogenic mutants and different growth temperatures were selected to manipulate the membrane fatty acid composition of E. coli before challenging the bacteria with different relative humidity (RH) levels in an aerosol chamber. Among the mutants (fabR - , cfa. fadA - ), fabR - had the lowest membrane fluidity index (FI) and generally showed a higher survival than the parental strain. Surprisingly, its resistance to airborne stress was so strong that its viability was fully maintained even after airborne suspension at 40% RH, a harsh RH level to bacterial survival. Moreover, E. coli cultured at 20 °C with a higher FI than that at 30 and 37 °C generally had a lower survival after aerosolization and airborne suspension. Unlike FI, individual fatty acid and cyclopropane fatty acid composition did not relate to the bacterial survival. Lipid peroxidation of the membrane was undetected in all the bacteria. Membrane fluidity plays a stronger role in determining the bacteria survival during airborne suspension than during aerosolization. Certain relationships between FI and bacteria survival were identified, which could help predict the transmission of bacteria under different conditions.

  10. Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth

    Energy Technology Data Exchange (ETDEWEB)

    Degreif, Daniel [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Technical Univ. of Darmstadt (Germany); de Rond, Tristan [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States); Bertl, Adam [Technical Univ. of Darmstadt (Germany); Keasling, Jay D. [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technical Univ. of Denmark, Lyngby (Denmark); Budin, Itay [Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Univ. of California, Berkeley, CA (United States)

    2017-03-18

    Cells modulate lipid metabolism in order to maintain membrane homeostasis. In this paper, we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggered cell-cell adhesion (flocculation), a phenomenon characteristic of industrial yeast but uncommon in laboratory strains. We find that ER lipid saturation sensors induce expression of FLO1 – encoding a cell wall polysaccharide binding protein – independently of its canonical regulator. In wild-type cells, Flo1p-dependent flocculation occurs under oxygen-limited growth, which reduces unsaturated lipid synthesis and thus serves as the environmental trigger for flocculation. Transcriptional analysis shows that FLO1 is one of the most highly induced genes in response to changes in lipid unsaturation, and that the set of membrane fluidity-sensitive genes is globally activated as part of the cell's long-term response to hypoxia during fermentation. Finally, our results show how the lipid homeostasis machinery of budding yeast is adapted to carry out a broad response to an environmental stimulus important in biotechnology.

  11. Determining Factors for Fast Corneal Sensitivity Recovery After Pterygium Excision

    OpenAIRE

    Julio Morán, Gemma; Campos, Pamela; Pujol Vives, Pere; Munguia, Aitana; Mas Aixalà, Enric

    2016-01-01

    Purpose: To establish determining factors for fast corneal sensitivity (CS) recovery after pterygium excision. Methods: Thirty-two eyes of 14 males and 18 females with primary nasal pterygium were recruited. Differences in CS (in the 4 quadrants and the center using a Cochet–Bonnet esthesiometer), pterygium corneal area (PCA), tear osmolarity, tear break-up time, Schirmer test, and ocular symptoms were analyzed before and 1 month after lesion excision. The relationship between CS recovery...

  12. Rapid and sensitive determination of deuterium concentration by gas chromatography

    International Nuclear Information System (INIS)

    Takahashi, Tomiki; Ohokoshi, Sumio; Shinriki, Nariko; Sato, Toshio

    1984-01-01

    Gas chromatographic determination of hydrogen isotopes D 2 and HD has hitherto been carried out with a molecular sieve column kept at -195 0 C under the H 2 carrier gas. However, the amount of D 2 in hydrogen gas containing low HD concentration of less than 5 % can be practically neglected judging from the equilibrium constant of H 2 -D 2 exchange reaction. Therefore, there is no need to separate HD from D 2 . As an improvement, in this paper, the gas chromatographic determination of HD in low concentration ( 2 as a carrier gas enabled us to enhance the cell current of TCD drastically, hence gave rise to high sensitivity of HD detection. The limit of determination of the concentration of HD was 0.01%. In the case of the higher concentration (>5%) of HD in hydrogen gas, D 2 and HD have been separated and determined by the method described above, but this method takes more than ten minutes. Therefore, we designed a new gas chromatographic analysis of the HD-D 2 mixture with an activated alumina column at -195 0 C under the H 2 carrier gas (330 ml/min). The advantages of this method are in (1) rapid analysis (in 1 min), (2) no need of the rigid activation temperature ((110--250) 0 C), (3) no change of the relative molar sensitivity of HD to D 2 at the various flow rates of H 2 carrier gas ((100--300)ml/min). (author)

  13. Physical determinants of radiation sensitivity in bacterial spores

    International Nuclear Information System (INIS)

    Powers, E.L.

    1982-01-01

    Several factors modifying radiation sensitivity in dry bacterial spores are described and discussed. Vacuum inducing the loss of critical structural water, very low dose rates of radiation from which the cell may recover, radiations of high linear energy transfer, and the action of temperature over long periods of time on previously irradiated cells are recognized from extensive laboratory work as important in determining survival of spores exposed to low radiation doses at low temperatures for long periods of time. Some extensions of laboratory work are proposed

  14. The fluidities of digital learning environments and resources

    DEFF Research Database (Denmark)

    Hansbøl, Mikala

    2012-01-01

    The research project “Educational cultures and serious games on a global market place” (2009-2011) dealt with the challenge of the digital learning environment and hence it’s educational development space always existing outside the present space and hence scope of activities. With a reference...... and establishments of the virtual universe called Mingoville.com, the research shows a need to include in researchers’ conceptualizations of digital learning environments and resources, their shifting materialities and platformations and hence emerging (often unpredictable) agencies and educational development...... spaces. Keywords: Fluidity, digital learning environment, digital learning resource, educational development space...

  15. The fluidity of Thai women's gendered and sexual subjectivities.

    Science.gov (United States)

    Thaweesit, Suchada

    2004-05-01

    This paper reports on an ethnographic study of gender and sexuality as factors within contemporary Thai factory women's subjectivities. Competing discourses of what it means to be a woman in contemporary Thai society make women's self-presentations fluid and incoherent. Data from participant-observation and open-ended interviews suggest that the fluidity and inconsistency of women's self-presentations reflect both their negative experiences and oppression within the Thai patriarchal system, and women's strength and resistance to the normative discourses that oppress them. By naming or reinterpreting experiences and desires in their own terms, Thai factory women can redraw elements of their own lives.

  16. MICROORGANISMS ANTIBIOTIC SENSITIVITY DETERMINATION IN URINARY TRACT INFECTIONS

    Directory of Open Access Journals (Sweden)

    Shapovalova O.V.

    2016-06-01

    Full Text Available Introduction. Nowadays Urinary tract infections (UTI are considered to be the most common bacterial infections. Escherichia coli is the most frequently uropathogen. Other microorganisms of the genera Enterococcus, Klebsiella, Enterobacter, Proteus, Morganella, Citrobacter, Serratia, Pseudomonas, Streptococcus, Staphylococcus, Candida are also isolated with variable frequency. In recent years there has been a decreasing tendency of the causative agents of UTI sensitivity to various antibiotics, which causes growth of an inefficiency treatment risk. In connection with the above the investigations were carried out with the purpose to identify the actual causative agents of bacteriuria and their sensitivity to antibiotics and antifungal drugs. Materials and methods. Bacteriological examination of urine was performed at 42 patients of SI "Sytenko Institute of Spine and Joint Pathology, AMS of Ukraine" clinic. The bacteriological method for determining the number of bacteria in the test material, cultural and bacterioscopic methods for identifying microorganisms and disk-diffusion method for sensitivity of microorganisms to antibiotics determining were used. The clinical material for the study was an average portion of the morning urine or urine collected by catheter. The biological material collection and bacteriological examination was carried by quantitative method, the isolated microorganisms identification and their sensitivity to antibiotics determining was performed by standard methods in accordance with current guidelines. We used the following antibiotics group to determine the microorganisms sensitivity: penicillin, cephalosporin, karbapenems, tetracyclines, aminoglycoside, fluoroquinolones, oxazolidinones, macrolides, lincosamides, glycopeptides, antifungal antibiotics. Results and discussion. During the biological material study 55 isolates of bacterial and fungal pathogens were obtained. The microorganisms’ concentration in urine was in

  17. Sensitive determination of citrinin based on molecular imprinted electrochemical sensor

    Energy Technology Data Exchange (ETDEWEB)

    Atar, Necip [Department of Chemical Engineering, Faculty of Engineering, Pamukkale University, Denizli (Turkey); Yola, Mehmet Lütfi, E-mail: mehmetyola@gmail.com [Department of Metallurgical and Materials Engineering, Faculty of Engineering, Sinop University, Sinop (Turkey); Eren, Tanju [Department of Chemical Engineering, Faculty of Engineering, Pamukkale University, Denizli (Turkey)

    2016-01-30

    Graphical abstract: - Highlights: • Citrinin-imprinted electrochemical sensor is developed for the sensitive detection of citrinin. • The nanomaterial and citrinin-imprinted surfaces were characterized by several methods. • Citrinin-imprinted electrochemical sensor is sensitive and selective in analysis of food. • Citrinin-imprinted electrochemical sensor is preferred to the other methods. - Abstract: In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H{sub 3}PW{sub 12}O{sub 40}, POM) functionalized reduced graphene oxide (rGO) was prepared for the determination of citrinin (CIT). The developed surfaces were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. CIT imprinted GCE was prepared via electropolymerization process of 80.0 mM pyrrole as monomer in the presence of phosphate buffer solution (pH 6.0) containing 20.0 mM CIT. The linearity range and the detection limit of the developed method were calculated as 1.0 × 10{sup −12}–1.0 × 10{sup −10} M and 2.0 × 10{sup −13} M, respectively. In addition, the voltammetric sensor was applied to rye samples. The stability and selectivity of the voltammetric sensor were also reported.

  18. Sensitive determination of citrinin based on molecular imprinted electrochemical sensor

    International Nuclear Information System (INIS)

    Atar, Necip; Yola, Mehmet Lütfi; Eren, Tanju

    2016-01-01

    Graphical abstract: - Highlights: • Citrinin-imprinted electrochemical sensor is developed for the sensitive detection of citrinin. • The nanomaterial and citrinin-imprinted surfaces were characterized by several methods. • Citrinin-imprinted electrochemical sensor is sensitive and selective in analysis of food. • Citrinin-imprinted electrochemical sensor is preferred to the other methods. - Abstract: In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H_3PW_1_2O_4_0, POM) functionalized reduced graphene oxide (rGO) was prepared for the determination of citrinin (CIT). The developed surfaces were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. CIT imprinted GCE was prepared via electropolymerization process of 80.0 mM pyrrole as monomer in the presence of phosphate buffer solution (pH 6.0) containing 20.0 mM CIT. The linearity range and the detection limit of the developed method were calculated as 1.0 × 10"−"1"2–1.0 × 10"−"1"0 M and 2.0 × 10"−"1"3 M, respectively. In addition, the voltammetric sensor was applied to rye samples. The stability and selectivity of the voltammetric sensor were also reported.

  19. Dynamic pressure sensitivity determination with Mach number method

    Science.gov (United States)

    Sarraf, Christophe; Damion, Jean-Pierre

    2018-05-01

    Measurements of pressure in fast transient conditions are often performed even if the dynamic characteristic of the transducer are not traceable to international standards. Moreover, the question of a primary standard in dynamic pressure is still open, especially for gaseous applications. The question is to improve dynamic standards in order to respond to expressed industrial needs. In this paper, the method proposed in the EMRP IND09 ‘Dynamic’ project, which can be called the ‘ideal shock tube method’, is compared with the ‘collective standard method’ currently used in the Laboratoire de Métrologie Dynamique (LNE/ENSAM). The input is a step of pressure generated by a shock tube. The transducer is a piezoelectric pressure sensor. With the ‘ideal shock tube method’ the sensitivity of a pressure sensor is first determined dynamically. This method requires a shock tube implemented with piezoelectric shock wave detectors. The measurement of the Mach number in the tube allows an evaluation of the incident pressure amplitude of a step using a theoretical 1D model of the shock tube. Heat transfer, other actual effects and effects of the shock tube imperfections are not taken into account. The amplitude of the pressure step is then used to determine the sensitivity in dynamic conditions. The second method uses a frequency bandwidth comparison to determine pressure at frequencies from quasi-static conditions, traceable to static pressure standards, to higher frequencies (up to 10 kHz). The measurand is also a step of pressure generated by a supposed ideal shock tube or a fast-opening device. The results are provided as a transfer function with an uncertainty budget assigned to a frequency range, also deliverable frequency by frequency. The largest uncertainty in the bandwidth of comparison is used to trace the final pressure step level measured in dynamic conditions, owing that this pressure is not measurable in a steady state on a shock tube. A reference

  20. Sulfate and Chloride Resistance of High Fluidity Concrete including Fly Ash and GGBS for NPP

    International Nuclear Information System (INIS)

    Noh, Jea Myoung; Cho, Myung Sug

    2010-01-01

    Fly ash mixed concrete has been used for NPP concrete structures in Korea in order to prevent aging and improve durability since the Shin.Kori no.1,2 in 2005. Concentrated efforts to develop technology for the streamlining of construction work and to affect labor savings have been conducted in construction. The application of high fluidity concrete for nuclear power plants has been the research subject with the aim of further rationalization of construction works. Since high fluidity concrete can have the characteristics of high density and high strength without compaction. However, high fluidity concrete can cause thermal cracking by heat of hydration. For this reason, the amount of pozzolan binder should be increased in high fluidity concrete for nuclear power plants. In this study, the resistance of high fluidity concrete on sulfate and chloride was compared with that of the concrete currently using for nuclear power plants

  1. To deal with fluidity in the networked society

    DEFF Research Database (Denmark)

    Levinsen, Karin Tweddell

    2010-01-01

    In the globalized economies e-permeation has become a basic condition in our everyday lives. ICT can no longer be understood solely as artefacts and tools and computer-related literacy are no longer restricted to the ability to operate digital tools for specific purposes. The network society......, and therefore also eLearning are characterized by fluidity and the key competence for social actors in this ever changing e-permeated environment is the ability to cope with change - or Castells’ conceptualisation self-programming. Castells’ theory has influenced international definitions of future key...... competencies. Both lifelong learning and digital literacy understood 'bildun' have emerged as central for the definitions of and standards for future key competencies. However, definitions and standards only tell us about the desired destination and outcome of digital competence building. They tell us nothing...

  2. Neighborhood properties are important determinants of temperature sensitive mutations.

    Directory of Open Access Journals (Sweden)

    Svetlana Lockwood

    Full Text Available Temperature-sensitive (TS mutants are powerful tools to study gene function in vivo. These mutants exhibit wild-type activity at permissive temperatures and reduced activity at restrictive temperatures. Although random mutagenesis can be used to generate TS mutants, the procedure is laborious and unfeasible in multicellular organisms. Further, the underlying molecular mechanisms of the TS phenotype are poorly understood. To elucidate TS mechanisms, we used a machine learning method-logistic regression-to investigate a large number of sequence and structure features. We developed and tested 133 features, describing properties of either the mutation site or the mutation site neighborhood. We defined three types of neighborhood using sequence distance, Euclidean distance, and topological distance. We discovered that neighborhood features outperformed mutation site features in predicting TS mutations. The most predictive features suggest that TS mutations tend to occur at buried and rigid residues, and are located at conserved protein domains. The environment of a buried residue often determines the overall structural stability of a protein, thus may lead to reversible activity change upon temperature switch. We developed TS prediction models based on logistic regression and the Lasso regularized procedure. Through a ten-fold cross-validation, we obtained the area under the curve of 0.91 for the model using both sequence and structure features. Testing on independent datasets suggested that the model predicted TS mutations with a 50% precision. In summary, our study elucidated the molecular basis of TS mutants and suggested the importance of neighborhood properties in determining TS mutations. We further developed models to predict TS mutations derived from single amino acid substitutions. In this way, TS mutants can be efficiently obtained through experimentally introducing the predicted mutations.

  3. Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes

    Science.gov (United States)

    Zhou, Yunyou; Bian, Guirong; Wang, Leyu; Dong, Ling; Wang, Lun; Kan, Jian

    2005-06-01

    This paper describes the preparation of organic nanoparticles by reprecipitation method under sonication and vigorous stirring. Transmission electron microscopy (TEM) was used to characterize the size and size distribution of the luminescent nanoparticles. Their average diameter was about 25 nm with a size variation of ±18%. The fluorescence decay lifetime of the nanoparticles also was determined on a self-equipped fluorospectrometer with laser light source. The lifetime (˜0.09 μs) of nanoparticles is about three times long as that of the monomer. The nanoparticles were in abundant of hydrophilic groups, which increased their miscibility in aqueous solution. These organic nanoparticles have high photochemical stability, excellent resistance to chemical degradation and photodegradation, and a good fluorescence quantum yield (25%). The fluorescence can be efficiently quenched by nucleic acids. Based on the fluorescence quenching of nanoparticles, a fluorescence quenching method was developed for determination of microamounts of nucleic acids by using the nanoparticles as a new fluorescent probe. Under optimal conditions, maximum fluorescence quenching is produced, with maximum excitation and emission wavelengths of 345 and 402 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-19.0 μg ml -1 for calf thymus DNA (ct-DNA) and 0.3-19.0 μg ml -1 for fish sperm DNA (fs-DNA). The corresponding detection limits are 0.25 μg ml -1 for ct-DNA and 0.17 μg ml -1 for fs-DNA. The relative standard deviation of six replicate measurements is 1.3-2.1%. The method is simple, rapid and sensitive with wide linear range. The recovery and relative standard deviation are very satisfactory.

  4. Is skin penetration a determining factor in skin sensitization ...

    Science.gov (United States)

    Summary:Background. It is widely accepted that substances that cannot penetrate through the skin will not be sensitisers. Thresholds based on relevant physicochemical parameters such as a LogKow > 1 and a MW 1 is a true requirement for sensitisation.Methods. A large dataset of substances that had been evaluated for their skin sensitisation potential, together with measured LogKow values was compiled from the REACH database. The incidence of skin sensitisers relative to non-skin sensitisers below and above the LogKow = 1 threshold was evaluated. Results. 1482 substances with associated skin sensitisation outcomes and measured LogKow values were identified. 305 substances had a measured LogKow self-evident truth borne out from the widespread misconception that the ability to efficiently penetrate the stratum corneum is a key determinant of skin sensitisation potential and potency. Using the REACH data extracted to test out the validity of common assumptions in the skin sensitization AOP. Builds on trying to develop a proof of concept IATA

  5. Determination of aerodynamic sensitivity coefficients for wings in transonic flow

    Science.gov (United States)

    Carlson, Leland A.; El-Banna, Hesham M.

    1992-01-01

    The quasianalytical approach is applied to the 3-D full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. The quasianalytical approach is believed to be reasonably accurate and computationally efficient for 3-D problems.

  6. Study on fluidity of squeeze cast AZ91D magnesium alloy with different wall thicknesses

    Directory of Open Access Journals (Sweden)

    Chen Yun

    2014-03-01

    Full Text Available Rectangular cross-section specimens with different section thicknesses were prepared to study the influences of pouring temperature, mould temperature and squeeze velocity on the fluidity of squeeze cast AZ91D magnesium alloy by means of orthogonal test design method. The results show that pouring temperature, mould temperature and squeeze velocity can significantly affect the fluidity of magnesium alloy specimens with wall thickness no more than 4 mm, and the pouring temperature is the most influential factor on the fluidity of specimens with wall thickness of 1, 2 and 3 mm, while mould temperature is the one for specimens with wall thickness of 4 mm. Increasing pouring temperature between 700 °C and 750 °C is beneficial to the fluidity of AZ91D magnesium alloy, and increasing mould temperature significantly enhances the filling ability of thick (3 and 4 mm section castings. The fluidity of squeeze cast magnesium alloy increases with the increase of wall thickness. It is not recommended to produce magnesium alloy casting with wall thickness of smaller than 3 mm by squeeze cast process due to the poor fluidity. The software DPS was used to generate the regression model, and linear regression equations of the fluidity of squeeze cast AZ91D with different wall thicknesses are obtained using the test results.

  7. Determining Confounding Sensitivities In Eddy Current Thin Film Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn

    2016-07-01

    Determining Confounding Sensitivities In Eddy Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy current testing is performed using a commercially available, hand held eddy current probe (ETA3.3H spring loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring

  8. Membrane fatty acid composition and fluidity are involved in the resistance to freezing of Lactobacillus buchneri R1102 and Bifidobacterium longum R0175.

    Science.gov (United States)

    Louesdon, Séverine; Charlot-Rougé, Séverine; Tourdot-Maréchal, Raphaëlle; Bouix, Marielle; Béal, Catherine

    2015-03-01

    Determinations of membrane fatty acid composition and fluidity were used together with acidification activity and viability measurements to characterize the physiological state after freezing of Lactobacillus buchneri R1102 and Bifidobacterium longum R0175 cells harvested in the exponential and stationary growth phases. For both strains, lower membrane fluidity was achieved in cells harvested in the stationary growth phase. This change was linked to a lower unsaturated-to-saturated fatty acid ratio for both strains and a higher cyclic-to-saturated fatty acid ratio for L. buchneri R1102 alone. These membrane properties were linked to survival and to maintenance of acidification activity of the cells after freezing, which differed according to the strain and the growth phase. Survival of B. longum R0175 was increased by 10% in cells with low membrane fluidity and high relative saturated fatty acid contents, without any change in acidification activity. Acidification activity was more degraded (70 min) in L. buchneri R1102 cells displaying low membrane fluidity and high saturated and cyclic fatty acid levels. Finally, this study showed that membrane modifications induced by the growth phase differed among bacterial strains in terms of composition. By lowering membrane fluidity, these modifications could be beneficial for survival of B. longum R0175 during the freezing process but detrimental for maintenance of acidification activity of L. buchneri R1102. © 2014 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  9. Evaluation of ionizing radiation effects on recycled polyamide-6 by infrared spectroscopy and measures of fluidity index

    International Nuclear Information System (INIS)

    Evora, Maria Cecilia; Goncalez, Odair Lelis

    2000-01-01

    In this work are presented partial results from a set of experiments and analyses performed at CTA and IPEN laboratories for the characterization of the polyamide-6, recycled and irradiated with a 1.5 MeV electron beam with a 500 kGy dose. The experimental determinations were carried out using infrared spectroscopy with Fourier transform (FTIR), in the medium infrared region (MIR) and in the far infrared region (FAR), to evaluate if exist significant changes in the infrared absorption region of the amide groups due to the polyamide irradiation. Characteristics relative to the measured fluidity index were used to evaluate the irradiated material crosslinking. (author)

  10. Determination of a lower bound on Earth's climate sensitivity

    Directory of Open Access Journals (Sweden)

    STEPHEN E. Schwartz

    2013-09-01

    Full Text Available Transient and equilibrium sensitivity of Earth's climate has been calculated using global temperature, forcing and heating rate data for the period 1970–2010. We have assumed increased long-wave radiative forcing in the period due to the increase of the long-lived greenhouse gases. By assuming the change in aerosol forcing in the period to be zero, we calculate what we consider to be lower bounds to these sensitivities, as the magnitude of the negative aerosol forcing is unlikely to have diminished in this period. The radiation imbalance necessary to calculate equilibrium sensitivity is estimated from the rate of ocean heat accumulation as 0.37±0.03 W m−2 (all uncertainty estimates are 1−σ. With these data, we obtain best estimates for transient climate sensitivity 0.39±0.07 K (W m−2−1 and equilibrium climate sensitivity 0.54±0.14 K (W m−2−1, equivalent to 1.5±0.3 and 2.0±0.5 K (3.7 W m−2−1, respectively. The latter quantity is equal to the lower bound of the ‘likely’ range for this quantity given by the 2007 IPCC Assessment Report. The uncertainty attached to the lower-bound equilibrium sensitivity permits us to state, within the assumptions of this analysis, that the equilibrium sensitivity is greater than 0.31 K (W m−2−1, equivalent to 1.16 K (3.7 W m−2−1, at the 95% confidence level.

  11. How to Determine the Increasing Returns Sensitivity of Your Industry?

    NARCIS (Netherlands)

    M.H. Klein (Martin); E. den Hartigh; H.R. Commandeur (Harry); F. Langerak (Fred)

    2004-01-01

    textabstractIncreasing returns means that self-reinforcing mechanisms are at work within firms and markets. These mechanisms come in four forms: scale effects, learning effects, network effects and social interaction effects. Some industries are more sensitive to increasing returns than others. It

  12. Effects of causality on the fluidity and viscous horizon of quark-gluon plasma

    Science.gov (United States)

    Rahaman, Mahfuzur; Alam, Jan-e.

    2018-05-01

    The second-order Israel-Stewart-M u ̈ller relativistic hydrodynamics was applied to study the effects of causality on the acoustic oscillation in relativistic fluid. Causal dispersion relations have been derived with nonvanishing shear viscosity, bulk viscosity, and thermal conductivity at nonzero temperature and baryonic chemical potential. These relations have been used to investigate the fluidity of quark-gluon plasma (QGP) at finite temperature (T ). Results of the first-order dissipative hydrodynamics have been obtained as a limiting case of the second-order theory. The effects of the causality on the fluidity near the transition point and on the viscous horizon are found to be significant. We observe that the inclusion of causality increases the value of fluidity measure of QGP near Tc and hence makes the flow strenuous. It was also shown that the inclusion of the large magnetic field in the causal hydrodynamics alters the fluidity of QGP.

  13. Lipid engineering reveals regulatory roles for membrane fluidity in yeast flocculation and oxygen-limited growth

    DEFF Research Database (Denmark)

    Degreif, Daniel; de Rond, Tristan; Bertl, Adam

    2017-01-01

    Cells modulate lipid metabolism in order to maintain membrane homeostasis. Here we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggere...

  14. Protein separations using enhanced-fluidity liquid chromatography.

    Science.gov (United States)

    Bennett, Raffeal; Olesik, Susan V

    2017-11-10

    Enhanced-fluidity liquid chromatography (EFLC) methods using methanol/H 2 O/CO 2 and hydrophilic interaction liquid chromatography (HILIC) were explored for the separation of proteins and peptides. EFLC is a separation mode that uses a mobile phase made of conventional solvents combined with liquid carbon dioxide (CO 2 ) in subcritical conditions. The addition of liquid CO 2 enhances diffusivity and decreases viscosity while maintaining mixture polarity, which typically results in reduced time of analysis. TFA additive and elevated temperature were leveraged as key factors in the separation of a 13-analyte intact protein mixture in under 5min. Under these conditions EFLC showed modest improvement in terms of peak asymmetry and analysis time over the competing ACN/H 2 O separation. Protein analytes detected by electrospray ionization - quadrupole time of flight, were shown to be unaffected by the addition of CO 2 in the mobile phase. Herein, the feasibility of separating hydrophilic proteins up to 80kDa (with transferrin) is demonstrated for CO 2 -containing mobile phases. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Investigation to determine the absolute sensitivity of Rh SPNDs

    International Nuclear Information System (INIS)

    Adorian, F.; Patai Szabo, S.; Pos, I.

    1998-01-01

    The goal of the work was to find an empirical sensitivity function of the Rh SPNDs used in VVER-440 reactors and to investigate the accuracy and adequateness of the detector signal predicting capability of the associated model. In our case the model was based on the HELIOS transport code and the C-PORCA nodal code. A statistical sensitivity analysis versus some selected parameters (e.g. enrichment, burn-up) has been carried out by using a substantial amount of measured data. We also investigated the stability of the electron collecting probability of the detectors versus their burn-up and other parameters with the aim of obtaining a tuned semi-empirical formula for the detector burnup correction. (Authors)

  16. Price sensitivity to tourism activities: looking for determinant factors

    OpenAIRE

    Lorenzo Masiero; Juan L. Nicolau

    2011-01-01

    The literature contains evidence that there is a marked heterogeneity in price responses to tourism products, leading to a great variety of tourist sensitivities to price. Thus the role price plays is complex, and a particularly challenging aspect of this complexity is that its effect is not unambiguous, thereby negating the idea that the demand for tourism products and tourist activities can always be regarded as demand for ordinary goods. This article identifies and explains, as a novelty f...

  17. Effect of grain refinement on the fluidity of two commercial Al-Si foundry alloys

    Science.gov (United States)

    Dahle, A. K.; Tøndel, P. A.; Paradies, C. J.; Arnberg, L.

    1996-08-01

    The effect of grain refinement on the fluidity of AlSi7Mg and AlSi11Mg has been investigated by spiral tests. Two different types of grain refiners have been evaluated. An AlTi5Bl master alloy was added to different Ti contents. Since the commercial alloys had a high initial content of titanium, model alloys were made to investigate the fluidity at low grain refiner additions. Commercial alloys grain refined only by boron additions have also been investigated. The results from the fluidity measurements have been verified by measuring the dendrite coherency point of the different cast alloys. Although different, the two methods show similar trends. The spirals from each fraction grain refiner cast were subsequently investigated metallographically at the tip of the spirals and at a reference point a distance behind, but no obvious difference in structure was observed. For both alloys, an increase in fluidity is observed as the content of grain refiner increases above 0.12 pct Ti, while the fluidity is impaired with increased grain refinement below 0.12 pct Ti. The alloys grain refined with ~0.015 pct B show the highest fraction solid at dendrite coherency, the smallest grain size, and the best fluidity.

  18. Effect of plasma membrane fluidity on serotonin transport by endothelial cells

    International Nuclear Information System (INIS)

    Block, E.R.; Edwards, D.

    1987-01-01

    To evaluate the effect of plasma membrane fluidity of lung endothelial cells on serotonin transport, porcine pulmonary artery endothelial cells were incubated for 3 h with either 0.1 mM cholesterol hemisuccinate, 0.1 mM cis-vaccenic acid, or vehicle (control), after which plasma membrane fluidity and serotinin transport were measured. Fluorescence spectroscopy was used to measure fluidity in the plasma membrane. Serotonin uptake was calculated from the disappearance of [ 14 C]-serotonin from the culture medium. Cholesterol decreased fluidity in the subpolar head group and central and midacyl side-chain regions of the plasma membrane and decreased serotonin transport, whereas cis-vaccenic acid increased fluidity in the central and midacyl side-chain regions of the plasma membrane and also increased serotonin transport. Cis-vaccenic acid had no effect of fluidity in the subpolar head group region of the plasma membrane. These results provide evidence that the physical state of the central and midacyl chains within the pulmonary artery endothelial cell plasma membrane lipid bilayer modulates transmembrane transport of serotonin by these cells

  19. Influence of membrane fluidity on human immunodeficiency virus type 1 entry

    International Nuclear Information System (INIS)

    Harada, Shinji; Yusa, Keisuke; Monde, Kazuaki; Akaike, Takaaki; Maeda, Yosuke

    2005-01-01

    For penetration of human immunodeficiency virus type 1 (HIV-1), formation of fusion-pores might be required for accumulating critical numbers of fusion-activated gp41, followed by multiple-site binding of gp120 with receptors, with the help of fluidization of the plasma membrane and viral envelope. Correlation between HIV-1 infectivity and fluidity was observed by treatment of fluidity-modulators, indicating that infectivity was dependent on fluidity. A 5% decrease in fluidity suppressed the HIV-1 infectivity by 56%. Contrarily, a 5% increase in fluidity augmented the infectivity by 2.4-fold. An increased temperature of 40 deg C or treatment of 0.2% xylocaine after viral adsorption at room temperature enhanced the infectivity by 2.6- and 1.5-fold, respectively. These were inhibited by anti-CXCR4 peptide, implying that multiple-site binding was accelerated at 40 deg C or by xylocaine. Thus, fluidity of both the plasma membrane and viral envelope was required to form the fusion-pore and to complete the entry of HIV-1

  20. Determination of cyanide by a highly sensitive indirect spectrophotometric method.

    Science.gov (United States)

    Blanco, M; Maspoch, S

    1984-01-01

    Complexation of Pd(2+) with cyanide inhibits the extraction of the palladium complex of 5-phenylazo-8-aminoquinoline. This effect is used for the indirect spectrophotometric determination of cyanide at the mug level. Cyanide in industrial waste water and in sea-water is determined after distillation as HCN from the sample and collection in sodium hydroxide solution.

  1. Reliability of direct sensitivity determination of blood cultures

    International Nuclear Information System (INIS)

    Noman, F.; Ahmed, A.

    2008-01-01

    The aim of this study was to evaluate the error in interpreting antimicrobial sensitivity by direct method when compared to standard method and find out if specific antibiotic-organism combination had more discrepancies. All blood culture samples received at Microbiology Laboratory from 1st July 2006 to 31st August 2006 were ncluded in the study. All samples were inoculated in automated blood culture system BACTEC 9240 which contained enriched Soybean-Casein Digest broth with CO/sub 2/. Once positive, bottles were removed from system; gram staining of the positive broths was done. Susceptibility test was performed from positive broth, on MHA (Mueller-Hinton Agar), with antibiotics panel according to gram stain result. All positive broths were also sub-cultured on blood agar, chocolate agar and McConkey agar for only gram-negative rods. Next day, the zone sizes of all antibiotics were recorded using measuring scale and at the same time susceptibility test was repeated from isolated colonies from subcultures, with inoculums prepared of McFarland 0.5 standard 0.2 Staphylococcus aureus (ATCC 29213); E.coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853) were included as quality control strain. Zone sizes were interpreted as sensitive (S), resistant (R) and intermediate (I) according to CLSI recommendation. Two results were compared and recorded. Out of a total 1083 combinations, zone diameters by standard method were either equal or greater than direct zone diameter (never smaller). Most of the discrepancies were in b-lactam/b-lactamase combinations and aminoglycosides. While reporting these groups of antibiotics with direct sensitivity test, one should be cautious. These are the major antibiotic used for life-threatening infections. In case of being heavy/lighter standard inoculums or marginal zones, repeating with standard method should be preferred to minimize the chances of error. (author)

  2. Crisis or Fluidity? Florian Znaniecki’s Theory of Civilization

    Directory of Open Access Journals (Sweden)

    Elżbieta Hałas

    2017-01-01

    Full Text Available The preoccupation with the processes of globalization, which has become a key concept in the analysis of the sociocultural condition of postmodernity, has led to a decreased interest in the theory of civilization. The ideological burden of the concept of civilization and its stigmatization by critics of post-Enlightenment modernity also contribute to this current state. However, issues associated with the processes of civilization have once again come to the fore, as shown by the reconstruction of threads associated with civilization in social theory, including sociological works. The views on civilization presented by Weber, Durkheim and Mauss, by their successors Sorokin, Elias and Nelson, down to the contemporary publications of Huntington and Eisenstadt are widely known, whereas works published on this subject in Polish by Florian Znaniecki are not. On a backdrop of the genesis of civilization-associated discourse and its antinomy as regards religion, the article presents Znaniecki’s concept of civilization processes as the social integration of culture, developed on the basis of his theory of cultural and social systems. Two types of human participation in culture are significant here: cultural communities and social groups which create a cultural bond. The de-civilizing processes which Znaniecki described are shown. The article analyzes Znaniecki’s idea of a fluid civilization and the conditions which are necessary for its existence, in the shape of reflexive cultural knowledge as the answer to a cultural crisis. The new type of cultural crisis stems from cultural innovations. The article shows the differences between Znaniecki’s concept of fluidity and Bauman’s liquid modernity. It presents the concept of “civilization of the future” as a pan-human civilization, which requires the formation of a new type of cultural community – the world culture society.

  3. NK sensitivity of neuroblastoma cells determined by a highly sensitive coupled luminescent method

    International Nuclear Information System (INIS)

    Ogbomo, Henry; Hahn, Anke; Geiler, Janina; Michaelis, Martin; Doerr, Hans Wilhelm; Cinatl, Jindrich

    2006-01-01

    The measurement of natural killer (NK) cells toxicity against tumor or virus-infected cells especially in cases with small blood samples requires highly sensitive methods. Here, a coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase release from injured target cells was used to evaluate the cytotoxicity of interleukin-2 activated NK cells against neuroblastoma cell lines. In contrast to most other methods, CLM does not require the pretreatment of target cells with labeling substances which could be toxic or radioactive. The effective killing of tumor cells was achieved by low effector/target ratios ranging from 0.5:1 to 4:1. CLM provides highly sensitive, safe, and fast procedure for measurement of NK cell activity with small blood samples such as those obtained from pediatric patients

  4. Clinical interest in determinations of cellular radiation sensitivity

    International Nuclear Information System (INIS)

    Suit, H.D.; Baumann, M.; Skates, S.; Convery, K.

    1989-01-01

    This review concludes that there are high expectations that measurements of cell survival in tumor and normal tissues at dose levels employed clinically will yield information of predictive value. Even though the absolute values for SF 2 and its distribution may not be real for the in vivo situation, the measured SF 2 may be of value as a means for ranking sensitivity. In actual clinical practice this would not be expected to be the only predictor employed, but rather one of several prognostic indicators. Hopefully, SF 2 can be developed to be an especially powerful one. There are prospective clinical evaluations of such measurements in progress. Early results are supportive of this approach (Brock et al. 1989a). (author)

  5. Sensitive amperometric determination of hydrazine using a carbon ...

    Indian Academy of Sciences (India)

    Silver-loaded nanozeolite-L-modified carbon paste electrode (Ag/L–CPE) was used as a novel sensing platform for enhanced electrocatalytic oxidation and determination of hydrazine. Zeolite L nanoparticles were synthesized via hydrothermal approach and then characterized using various techniques such as X-ray ...

  6. A Study on the Evaluation of Field Application of High-Fluidity Concrete Containing High Volume Fly Ash

    Directory of Open Access Journals (Sweden)

    Yun-Wang Choi

    2015-01-01

    Full Text Available In the recent concrete industry, high-fluidity concrete is being widely used for the pouring of dense reinforced concrete. Normally, in the case of high-fluidity concrete, it includes high binder contents, so it is necessary to replace part of the cement through admixtures such as fly ash to procure economic feasibility and durability. This study shows the mechanical properties and field applicability of high-fluidity concrete using mass of fly ash as alternative materials of cement. The high-fluidity concrete mixed with 50% fly ash was measured to manufacture concrete that applies low water/binder ratio to measure the mechanical characteristics as compressive strength and elastic modulus. Also, in order to evaluate the field applicability, high-fluidity concrete containing high volume fly ash was evaluated for fluidity, compressive strength, heat of hydration, and drying shrinkage of concrete.

  7. Increased fluidity and oxidation of malarial lipoproteins: relation with severity and induction of endothelial expression of adhesion molecules

    Directory of Open Access Journals (Sweden)

    Looareesuwan Sornchai

    2004-06-01

    Full Text Available Abstract Introduction Oxidative stress has been demonstrated in malaria. The potential oxidative modification of lipoproteins derived from malaria patients was studied. These oxidized lipids may have role in pathogenesis of malaria. Method The plasma lipid profile and existence of oxidized forms of very low density lipoprotein (VLDL, low density lipoprotein (LDL and high density lipoprotein (HDL were investigated in malaria (17 mild and 24 severe patients and 37 control subjects. Thiobarbituric acid reactive substances (TBARs, conjugated dienes, tryptophan fluorescence and fluidity of lipoproteins were determined as markers of oxidation. The biological effect of malarial lipoproteins was assessed by the expression of adhesion molecules on endothelial cells. Results Malarial lipoproteins had decreased cholesterol (except in VLDL and phospholipid. The triglyceride levels were unchanged. The cholesterol/phospholipid ratio of LDL was decreased in malaria, but increased in VLDL and HDL. TBARs and conjugate dienes were increased in malarial lipoproteins, while the tryptophan fluorescence was decreased. The fluidity of lipoproteins was increased in malaria. These indicated the presence of oxidized lipoproteins in malaria by which the degree of oxidation was correlated with severity. Of three lipoproteins from malarial patients, LDL displayed the most pronounced oxidative modification. In addition, oxidized LDL from malaria patients increased endothelial expression of adhesion molecules. Conclusion In malaria, the lipoproteins are oxidatively modified, and the degree of oxidation is related with severity. Oxidized LDL from malarial patients increases the endothelial expression of adhesion molecules. These suggest the role of oxidized lipoproteins, especially LDL, on the pathogenesis of disease.

  8. Differences in Sexual Orientation Diversity and Sexual Fluidity in Attractions Among Gender Minority Adults in Massachusetts.

    Science.gov (United States)

    Katz-Wise, Sabra L; Reisner, Sari L; Hughto, Jaclyn White; Keo-Meier, Colton L

    2016-01-01

    This study characterized sexual orientation identities and sexual fluidity in attractions in a community-based sample of self-identified transgender and gender-nonconforming adults in Massachusetts. Participants were recruited in 2013 using bimodel methods (online and in person) to complete a one-time, Web-based quantitative survey that included questions about sexual orientation identity and sexual fluidity. Multivariable logistic regression models estimated adjusted risk ratios (aRRs) and 95% confidence intervals (95% CIs) to examine the correlates of self-reported changes in attractions ever in lifetime among the whole sample (n = 452) and after transition among those who reported social gender transition (n = 205). The sample endorsed diverse sexual orientation identities: 42.7% queer, 19.0% other nonbinary, 15.7% bisexual, 12.2% straight, and 10.4% gay/lesbian. Overall, 58.2% reported having experienced changes in sexual attractions in their lifetime. In adjusted models, trans masculine individuals were more likely than trans feminine individuals to report sexual fluidity in their lifetime (aRR = 1.69; 95% CI = 1.34, 2.12). Among those who transitioned, 64.6% reported a change in attractions posttransition, and trans masculine individuals were less likely than trans feminine individuals to report sexual fluidity (aRR = 0.44; 95% CI = 0.28, 0.69). Heterogeneity of sexual orientation identities and sexual fluidity in attractions are the norm rather than the exception among gender minority people.

  9. Evidence that survival of γ-irradiated Escherichia coli is influenced by membrane fluidity

    International Nuclear Information System (INIS)

    Yatvin, M.B.

    1976-01-01

    Survival studies have been carried out on an Escherichia coli auxotroph (K-12 strain K1060) defective in both fatty acid degradation and in unsaturated fatty acid biosynthesis. Cultures were grown overnight in media supplemented with either oleic or linolenic acid, and γ-irradiated at two temperatures. Gas chromatography of total cellular fatty acids demonstrated marked differences in the compositions. In the bacteria grown in oleate, plamitate accounted for 35% and oleate 43%, whereas those grown in linolenate had no oleate but contained 56% palmitate and 35% linolenate. The loss (35%) in total DNA radioactivity from ( 3 H)TdR labelled cells after irradiation at room temperature or on ice, was essentially the same in bacteria grown with linoleic or oleic acid medium. The survival of linolenic substituted bacteria was altered little by irradiation at ice-bath temperature, but the oleic-grown bacteria were much more radiosensitive when irradiated and plated from the cold. The temperatures of the membrane phase transitions are such that at ice-bath temperature (approximately 3 to 5 0 C) only the membrane of the linolenate grown bacteria could possibly still be in the liquid (unorganized) state. The results therefore indicate that one of the factors influencing survival of irradiated bacteria may be membrane fluidity, and the membranes are an important factor in determining the extent of damage, 'repair' and ultimate survival in irradiated cells. (U.K.)

  10. Agarose Gel Electrophoresis Reveals Structural Fluidity of a Phage T3 DNA Packaging Intermediate

    Science.gov (United States)

    Serwer, Philip; Wright, Elena T.

    2012-01-01

    We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (1) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for stabilization of structure and then (2) determining of effective radius by two-dimensional agarose gel electrophoresis (2d-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2d-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging. PMID:22222979

  11. Agarose gel electrophoresis reveals structural fluidity of a phage T3 DNA packaging intermediate.

    Science.gov (United States)

    Serwer, Philip; Wright, Elena T

    2012-01-01

    We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (i) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for the stabilization of structure and then (ii) determining effective radius by two-dimensional agarose gel electrophoresis (2D-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase the production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2D-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when the ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Bile salt-induced increases in duodenal brush-border membrane proton permeability, fluidity, and fragility

    International Nuclear Information System (INIS)

    Zhao, D.L.; Hirst, B.H.

    1990-01-01

    Rabbit duodenal brush-border membrane vesicles were treated in vitro with deoxycholate, glycodeoxycholate, or taurodeoxycholate. Intravesicular [14C]glucose space at equilibrium, 0.54 microliters/mg protein, was reduced by exposure to the three bile salts in a concentration (0.1-5.0 mM)-dependent manner, equatable with increased membrane fragility. Net proton permeability (Pnet), determined by acridine orange fluorescence quenching, was increased from 6.3 x 10(-4) cm/sec in untreated vesicles, by approximately 120, 150, and 170%, by treatment with bile salts at 0.1, 0.5 and 1.0 mM, respectively. The three bile salts were equipotent. The increases in membrane fragility and Pnet were not accompanied by significant increases in membrane fluidity, as assessed from steady-state and time-resolved diphenylhexatriene fluorescence anisotropy. The data demonstrate direct effects of bile salts on duodenal apical membrane fragility and proton permeability that are likely to be early events in bile salt-induced mucosal damage

  13. Sensitive determination of citrinin based on molecular imprinted electrochemical sensor

    Science.gov (United States)

    Atar, Necip; Yola, Mehmet Lütfi; Eren, Tanju

    2016-01-01

    In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H3PW12O40, POM) functionalized reduced graphene oxide (rGO) was prepared for the determination of citrinin (CIT). The developed surfaces were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. CIT imprinted GCE was prepared via electropolymerization process of 80.0 mM pyrrole as monomer in the presence of phosphate buffer solution (pH 6.0) containing 20.0 mM CIT. The linearity range and the detection limit of the developed method were calculated as 1.0 × 10-12-1.0 × 10-10 M and 2.0 × 10-13 M, respectively. In addition, the voltammetric sensor was applied to rye samples. The stability and selectivity of the voltammetric sensor were also reported.

  14. Membrane fluidity increases during apoptosis of sheep ileal Peyer's patch B cells

    International Nuclear Information System (INIS)

    Jourd'heuil, D.; Aspinall, A.; Reynolds, J.D.; Meddings, J.B.

    1996-01-01

    To investigate specific plasma membrane structural changes associated with apoptosis, whole cells and purified plasma membranes of apoptotic B cells from the ileal Peyer's patch of sheep were analyzed for their 'membrane fluidity'. The ileal Peyer's patch of sheep provided a large number of B cells required for plasma membrane isolation (>5 x 10 9 ). As the incidence of apoptosis increased with time of culture, the fluidity of purified plasma membranes, as measured with the fluorophore DPH (diphenylhexatriene), increased. To evaluate this phenomenon with intact cells, B cells at different apoptotic stages were fractionated on discontinuous Percoll gradients. Similar results were obtained using the fluorophore TMA-DPH (trimethylammoniumdiphenylhexatriene), which has been shown to localize specifically to the plasma membrane. Functionally, the increase in plasma membrane fluidity associated with apoptosis may represent either a mechanism to cycle phosphatidylserine to the outer leaflet, mediating phagocytic recognition of apoptotic cells, or a consequence of this event. (author). 20 refs., 1 tab., 4 figs

  15. Radioactivity measurements for determining bacterial increase and sensitivity to antibiotics. [/sup 14/C tracer

    Energy Technology Data Exchange (ETDEWEB)

    Jaszsagi-Nagy, E [Magyar Tudomanyos Akademia, Budapest; Lendvay, J [Orszagos Frederic Joliot-Curie Sugarbiologiai es Sugaregeszsegugyi Kutato Intezet, Budapest (Hungary)

    1976-01-01

    The authors elaborated a sensitive and objective measuring method for determining the bacteria increase in biological material and the sensitivity to antibiotics. When /sup 14/C glucose is added to the medium as the single source of sugar, the respiratory carbon dioxide formed by the bacteria reflects the rate of increase. The released /sup 14/C dioxide can be measured continuously without loss to the environment and the degree of bacterial infection and the antibiotic activity, respectively, can be determined.

  16. Fluidity models in ancient Greece and current practices of sex assignment.

    Science.gov (United States)

    Chen, Min-Jye; McCann-Crosby, Bonnie; Gunn, Sheila; Georgiadis, Paraskevi; Placencia, Frank; Mann, David; Axelrad, Marni; Karaviti, L P; McCullough, Laurence B

    2017-06-01

    Disorders of sexual differentiation such as androgen insensitivity and gonadal dysgenesis can involve an intrinsic fluidity at different levels, from the anatomical and biological to the social (gender) that must be considered in the context of social constraints. Sex assignment models based on George Engel's biopsychosocial aspects model of biology accept fluidity of gender as a central concept and therefore help establish expectations within the uncertainty of sex assignment and anticipate potential changes. The biology underlying the fluidity inherent to these disorders should be presented to parents at diagnosis, an approach that the gender medicine field should embrace as good practice. Greek mythology provides many accepted archetypes of change, and the ancient Greek appreciation of metamorphosis can be used as context with these patients. Our goal is to inform expertise and optimal approaches, knowing that this fluidity may eventually necessitate sex reassignment. Physicians should provide sex assignment education based on different components of sexual differentiation, prepare parents for future hormone-triggered changes in their children, and establish a sex-assignment algorithm. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Emotion Talk in Preschool Same-Sex Friendship Groups: Fluidity over Time and Context.

    Science.gov (United States)

    Kyratzis, Amy

    2001-01-01

    Examined "emotion talk" among 3- and 4-year-old peers in a children's center in different contexts over the academic year. Found that the boys' group evolved norms against expression of being scared with norms downgrading girl characteristics. Boys' and girls' groups showed contextual fluidity in expressing emotion and emotion talk that…

  18. Relational and sexual fluidity in females partnered with male-to-female transsexual persons.

    Science.gov (United States)

    Aramburu Alegría, C

    2013-03-01

    This paper reports on a study examining sexuality in females who remain partnered with male-to-female transsexual persons. Participants' self-view and sexual fluidity following their partners' transition from man to woman is examined. Sixteen females participated in in-depth, semi-structured interviews. An inductive process of data analysis was conducted, using the constant comparative method, an iterative process by which data are compared within and across subjects. Data were collected until thematic saturation was achieved. Four themes related to sexuality emerged: (1) questioning of sexual orientation; (2) sexual orientation categorization; (3) relational fluidity without sexual relations; and (4) relational fluidity with sexual relations. Participants maintained a heterosexual identity, yet modified their self-view to include an identity that reflected their reformed relationship. The majority of the respondents reported sexual lives that were active or evolving. Others remained in relationships that no longer included sexual activity. The study findings highlight the potential fluidity within the sexual and relational lives of females, and can enhance healthcare providers' preparedness and efficacy with diverse populations. Providers are in a unique position to offer resources to patients who identify as sexually or gender-diverse, or who are in relationships with sexually or gender-diverse persons. © 2012 Blackwell Publishing.

  19. Trends in educational fluidity after the fall of socialism in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Katrňák, T.; Simonová, Natalie

    2016-01-01

    Roč. 10, č. 3 (2016), s. 49-69 ISSN 1802-4637 R&D Projects: GA ČR GB14-36154G Institutional support: RVO:68378025 Keywords : educational fluidity * cohort analysis * educational inequality Subject RIV: AO - Sociology, Demography OBOR OECD: Sociology

  20. Fluidity models in ancient Greece and current practices of sex assignment

    Science.gov (United States)

    Chen, Min-Jye; McCann-Crosby, Bonnie; Gunn, Sheila; Georgiadis, Paraskevi; Placencia, Frank; Mann, David; Axelrad, Marni; Karaviti, L.P; McCullough, Laurence B.

    2018-01-01

    Disorders of sexual differentiation such as androgen insensitivity and gonadal dysgenesis can involve an intrinsic fluidity at different levels, from the anatomical and biological to the social (gender) that must be considered in the context of social constraints. Sex assignment models based on George Engel’s biopsychosocial aspects model of biology accept fluidity of gender as a central concept and therefore help establish expectations within the uncertainty of sex assignment and anticipate potential changes. The biology underlying the fluidity inherent to these disorders should be presented to parents at diagnosis, an approach that the gender medicine field should embrace as good practice. Greek mythology provides many accepted archetypes of change, and the ancient Greek appreciation of metamorphosis can be used as context with these patients. Our goal is to inform expertise and optimal approaches, knowing that this fluidity may eventually necessitate sex reassignment. Physicians should provide sex assignment education based on different components of sexual differentiation, prepare parents for future hormone-triggered changes in their children, and establish a sex-assignment algorithm. PMID:28478088

  1. Born Both Ways: The Alloparenting Hypothesis for Sexual Fluidity in Women

    Directory of Open Access Journals (Sweden)

    Barry X. Kuhle

    2013-04-01

    Full Text Available Given the primacy of reproduction, same-sex sexual behavior poses an evolutionary puzzle. Why would selection fashion motivational mechanisms to engage in sexual behaviors with members of the same sex? We propose the alloparenting hypothesis, which posits that sexual fluidity in women is a contingent adaptation that increased ancestral women's ability to form pair bonds with female alloparents who helped them rear children to reproductive age. Ancestral women recurrently faced the adaptive problems of securing resources and care for their offspring, but were frequently confronted with either a dearth of paternal resources due to their mates' death, an absence of paternal investment due to rape, or a divestment of paternal resources due to their mates' extra-pair mating efforts. A fluid sexuality would have helped ancestral women secure resources and care for their offspring by promoting the acquisition of allomothering investment from unrelated women. Under this view, most heterosexual women are born with the capacity to form romantic bonds with both sexes. Sexual fluidity is a conditional reproductive strategy with pursuit of men as the default strategy and same-sex sexual responsiveness triggered when inadequate paternal investment occurs or when women with alloparenting capabilities are encountered. Discussion focuses on (a evidence for alloparenting and sexual fluidity in humans and other primates; (b alternative explanations for sexual fluidity in women; and (c fourteen circumstances predicted to promote same-sex sexual behavior in women.

  2. Effects of unripe Citrus hassaku fruits extract and its flavanone glycosides on blood fluidity.

    Science.gov (United States)

    Itoh, Kimihisa; Masuda, Megumi; Naruto, Shunsuke; Murata, Kazuya; Matsuda, Hideaki

    2010-01-01

    The enhancement of blood fluidity may lead to improvements in skin problems resulting from unsmooth circulation or blood stagnation. Since a 50% ethanolic extract (CH-ext) obtained from unripe Citrus hassaku fruits may be a useful ingredient in skin-whitening cosmetics, the present study was designed to examine the effect of CH-ext on blood fluidity. CH-ext concentration-dependently inhibited in vitro collagen-induced rabbit platelet aggregation and in vitro polybrene-induced rat erythrocyte aggregation. The CH-ext showed in vitro fibrinolysis activity in fibrin plate assay. Activity-guided fractionation of the CH-ext using antiplatelet activity, inhibitory activity of erythrocyte aggregation, and fibrinolysis activity revealed that these activities of CH-ext were attributable to naringenin-7-glycoside (prunin). Successive oral administration of CH-ext to rats inhibited the lipopolysaccharide (LPS)-induced decrease of blood platelets and fibrinogen, and LPS-induced increase of fibrin degradation products (FDP) in LPS-induced disseminated intravascular coagulation (DIC) model rats. Effects of CH-ext on blood fluidity were analyzed by a micro channel array flow analyzer (MC-FAN). Preventive oral administration of CH-ext to rats showed dose-dependent reduction of the passage time of whole blood flow of the DIC model rats in comparison with that of the vehicle control rats. These results imply that CH-ext may have effects which improve effects on blood fluidity.

  3. Highly sensitive determination of atropine using cobalt oxide nanostructures: Influence of functional groups on the signal sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Soomro, Razium Ali, E-mail: raziumsoomro@gmail.com [Interface Analysis Centre, School of Physics, University of Bristol, Bristol, BS8 1TL (United Kingdom); National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, 76080 (Pakistan); Nafady, Ayman [Department of Chemistry, College of Science, King Saud University, Riyadh (Saudi Arabia); Department of Chemistry, Faculty of Science, Sohag University, Sohag (Egypt); Hallam, Keith Richard [Interface Analysis Centre, School of Physics, University of Bristol, Bristol, BS8 1TL (United Kingdom); Jawaid, Sana [National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, 76080 (Pakistan); Al Enizi, Abdullah [Department of Chemistry, College of Science, King Saud University, Riyadh (Saudi Arabia); Sherazi, Syed Tufail Hussain; Sirajuddin [National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, 76080 (Pakistan); Ibupoto, Zafar Hussain [Dr M.A. Kazi Institute of Chemistry, University of Sindh, Jamshoro, 76080 (Pakistan); Willander, Magnus [Department of Science and Technology, Campus Norrkoping, Linkoping University, SE-60174, Norrkoping (Sweden)

    2016-12-15

    This study describes sensitive determination of atropine using glassy carbon electrodes (GCE) modified with Co{sub 3}O{sub 4} nanostructures. The as-synthesised nanostructures were grown using cysteine (CYS), glutathione (GSH) and histidine (HYS) as effective templates under hydrothermal action. The obtained morphologies revealed interesting structural features, including both cavity-based and flower-shaped structures. The as-synthesised morphologies were noted to actively participate in electro-catalysis of atropine (AT) drug where GSH-assisted structures exhibited the best signal response in terms of current density and over-potential value. The study also discusses the influence of functional groups on the signal sensitivity of atropine electro-oxidation. The functionalisation was carried with the amino acids originally used as effective templates for the growth of Co{sub 3}O{sub 4} nanostructures. The highest increment was obtained when GSH was used as the surface functionalising agent. The GSH-functionalised Co{sub 3}O{sub 4}-modified electrode was utilised for the electro-chemical sensing of AT in a concentration range of 0.01–0.46 μM. The developed sensor exhibited excellent working linearity (R{sup 2} = 0.999) and signal sensitivity up to 0.001 μM of AT. The noted high sensitivity of the sensor is associated with the synergy of superb surface architectures and favourable interaction facilitating the electron transfer kinetics for the electro-catalytic oxidation of AT. Significantly, the developed sensor demonstrated excellent working capability when used for AT detection in human urine samples with strong anti-interference potential against common co-existing species, such as glucose, fructose, cysteine, uric acid, dopamine and ascorbic acid. - Highlights: • Template-assisted growth of Co{sub 3}O{sub 4} nanostructures. • Shape-dependent electro-catalysis of atropine. • Effect of functionalisation of signal sensitivity.

  4. Differences in Sexual Orientation Diversity and Sexual Fluidity in Attractions among Gender Minority Adults in Massachusetts

    Science.gov (United States)

    Katz-Wise, Sabra L.; Reisner, Sari L.; White, Jaclyn M.; Keo-Meier, Colton L.

    2015-01-01

    This study characterized sexual orientation identities and sexual fluidity in attractions in a community-based sample of self-identified transgender and gender nonconforming adults in Massachusetts. Participants were recruited in 2013 using bi-model methods (online and in-person) to complete a one-time web-based quantitative survey that included questions about sexual orientation identity and sexual fluidity. Multivariable logistic regression models estimated Adjusted Risk Ratios (aRR) and 95% Confidence Intervals (95% CI) to examine the correlates of self-reported changes in attractions ever in lifetime among the whole sample (n=452) and after transition among those who reported social gender transition (n=205). The sample endorsed diverse sexual orientation identities: 42.7% queer, 19.0% other non-binary, 15.7% bisexual, 12.2% straight, 10.4% gay/lesbian. Overall, 58.2% reported having experienced changes in sexual attractions in their lifetime. In adjusted models, trans masculine individuals were more likely than trans feminine individuals to report sexual fluidity in their lifetime (aRR=1.69; 95% CI=1.34, 2.12). Among those who transitioned, 64.6% reported a change in attractions post-transition and trans masculine individuals were less likely than trans feminine individuals to report sexual fluidity (aRR=0.44; 95% CI=0.28, 0.69). Heterogeneity of sexual orientation identities and sexual fluidity in attractions are the norm rather than the exception among gender minority people. PMID:26156113

  5. 7-ketocholesterol inhibits Na,K-ATPase activity by decreasing expression of its α1-subunit and membrane fluidity in human endothelial cells.

    Science.gov (United States)

    Duran, M J; Pierre, S V; Lesnik, P; Pieroni, G; Bourdeaux, M; Dignat-Georges, F; Sampol, J; Maixent, J M

    2010-11-09

    As cholesterol, oxysterols, can insert the cell membrane and thereby modify the functions of membrane-bound proteins. The Na,K-ATPase is very sensitive to its lipid environment, seems to be involved in important endothelial functions as the regulation of nitric oxide (NO) release. The effects of 7-ketocholesterol , an oxysterol present in oxidized LDL, was investigated on Na,K-ATPase in isolated human endothelial cells. Cells were incubated 24h with lecithin-, cholesterol- or 7-ketocholesterol liposomes (6 μg/ml). K+-stimulated paranitrophenyl phosphatase activity, reflecting Na,K-ATPase activity, was evaluated as well as cell viability and lipoperoxidation. The expression of Na,K-ATPase subunits mRNAs and membrane fluidity were also investigated. As Na,K-ATPase and nitric oxide seem to be related, we determined the production of NO and the expression of endothelial NO synthase mRNAs. Na,K-ATPase activity was strongly decreased by 7-ketocholesterol. This decrease, not related to lipoperoxidation, was correlated with a decreased expression of the Na,K-ATPase α1-subunit messengers and with rigidity of plasma membranes. Cholesterol induced similar effects but was less potent than 7-ketocholesterol. Basal NO production and expression of endothelial NO synthase mRNAs were not modified by 7-ketocholesterol. Our new findings demonstrate that 7-ketocholesterol, used at non toxic doses, was very potent to disrupt the transport of ions by Na,K-ATPase and perturb membrane structure. These data demonstrate that 7-ketocholesterol induces endothelial dysfunction without cell death that may contribute to early events in atherosclerosis.

  6. Coal lithotypes before and after saturation with CO2; insights from micro- and mesoporosity, fluidity, and functional group distribution

    Science.gov (United States)

    Mastalerz, Maria; Drobniak, A.; Walker, R.; Morse, D.

    2010-01-01

    Four lithotypes, vitrain, bright clarain, clarain, and fusain, were hand-picked from the core of the Pennsylvanian Springfield Coal Member (Petersburg Formation) in Illinois. These lithotypes were analyzed petrographically and for meso- and micropore characteristics, functional group distribution using FTIR techniques, and fluidity. High-pressure CO2 adsorption isotherm analyses of these lithotypes were performed and, subsequently, all samples were reanalyzed in order to investigate the effects of CO2. After the high-pressure adsorption isotherm analysis was conducted and the samples were reanalyzed, there was a decrease in BET surface area for vitrain from 31.5m2/g in the original sample to 28.5m2/g, as determined by low-pressure nitrogen adsorption. Bright clarain and clarain recorded a minimal decrease in BET surface area, whereas for fusain there was an increase from 6.6m2/g to 7.9m2/g. Using low-pressure CO2 adsorption techniques, a small decrease in the quantity of the adsorbed CO2 is recorded for vitrain and bright clarain, no difference is observed for clarain, and there is an increase in the quantity of the adsorbed CO2 for fusain. Comparison of the FTIR spectra before and after CO2 injection for all lithotypes showed no differences with respect to functional group distribution, testifying against chemical nature of CO2 adsorption. Gieseler plastometry shows that: 1) softening temperature is higher for the post-CO2 sample (389.5??C vs. 386??C); 2) solidification temperature is lower for the post-CO2 sample (443.5??C vs. 451??C); and 3) the maximum fluidity is significantly lower for the post-CO2 sample (4 ddpm vs. 14 ddpm). ?? 2010 Elsevier B.V.

  7. Highly sensitive luminescence method of scandium determination in the products of metallurgical reprocessing

    International Nuclear Information System (INIS)

    Matveets, M.A.; Akhmetova, S.D.

    1988-01-01

    Highly sensitive reaction of scandium with 1,10-phenanthroline and eosin is used for the development of luminescence method of its determination in metallurgical products. The effect of interfering elements is eliminated by scandium extraction with monocarboxylic acids. The method permits to determine scandium content from 5 x 10 -5 % (Sr 0.15 - 0.25)

  8. Highly sensitive spectrophotometric kinetic determination of vanadium by catalysis of the gallic acid-bromate reaction

    International Nuclear Information System (INIS)

    Fukasawa, Tsutomu; Kawakubo, Susumu; Yamanouchi, Tatsuo

    1985-01-01

    Conditions are described for improving the speed and sensitivity of this catalytic determination of vanadium. The reaction of 0.018 M gallic acid with 0.96 M sodium bromate at pH 3.8 and double-beam spectrophotometric measurement at 380 nm are recommended. The highest practical sensitivity at 22-30 0 C was ca. 40 pg for an absorbance change of 0.0005, 50 times better than previously. The detection limit was ca. 0.5 ng of vanadium. Reaction at 50 0 C gave even better sensitivity. (Auth.)

  9. Determination of aerodynamic sensitivity coefficients based on the three-dimensional full potential equation

    Science.gov (United States)

    Elbanna, Hesham M.; Carlson, Leland A.

    1992-01-01

    The quasi-analytical approach is applied to the three-dimensional full potential equation to compute wing aerodynamic sensitivity coefficients in the transonic regime. Symbolic manipulation is used to reduce the effort associated with obtaining the sensitivity equations, and the large sensitivity system is solved using 'state of the art' routines. Results are compared to those obtained by the direct finite difference approach and both methods are evaluated to determine their computational accuracy and efficiency. The quasi-analytical approach is shown to be accurate and efficient for large aerodynamic systems.

  10. Immunoglobulin E sensitization to cross-reactive carbohydrate determinants: epidemiological study of clinical relevance and role of alcohol consumption

    DEFF Research Database (Denmark)

    Linneberg, Allan; Fenger, Runa Vavia; Husemoen, Lise-Lotte

    2010-01-01

    The determinants and biologic significance of IgE-mediated sensitization to cross-reactive carbohydrate determinants (CCDs) are not entirely known. An association between alcohol consumption and CCD sensitization has been reported in studies from Spain and Portugal.......The determinants and biologic significance of IgE-mediated sensitization to cross-reactive carbohydrate determinants (CCDs) are not entirely known. An association between alcohol consumption and CCD sensitization has been reported in studies from Spain and Portugal....

  11. Characterization of membrane lipid fluidity in human embryo cells malignantly transfer med post 238Pu α irradiation

    International Nuclear Information System (INIS)

    Qi Zirong; Sun Ling; Liu Guolian; Shen Zhiyuan

    1992-01-01

    The membrane lipid fluidity of malignantly transformed human embryo cells following 238 Pu α particlce irradiation in vitro has been studied. The results indicate that the ontogenesis depends on irradiation dose (Gy) and the membrane lipid fluidity in malignantly transformed cells is higher than that in normal embryo cells. With the microviscosity (η) of cells plotted against the cell counts, the correlation coefficient (γ) is calculated to be between 0.9936 and 0.9999. Since the malignant transformation of irradiated embryo cells is manifested early on cell membrane lipid, the fluidity of membrane lipid can be used as an oncologic marker

  12. A procedure for the improvement in the determination of a TXRF spectrometer sensitivity curve

    International Nuclear Information System (INIS)

    Bennun, Leonardo; Sanhueza, Vilma

    2010-01-01

    A simple procedure is proposed to determine the total reflection X-ray fluorescence (TXRF) spectrometer sensitivity curve; this procedure provides better accuracy and exactitude than the standard established method. It uses individual pure substances instead of the use of vendor-certified values of reference calibration standards, which are expensive and lack any method to check their quality. This method avoids problems like uncertainties in the determination of the sensitivity curve according to different standards. It also avoids the need for validation studies between different techniques, in order to assure the quality of their TXRF results. (author)

  13. Quantum dots and ionic liquid-sensitized effect as an efficient and green catalyst for the sensitive determination of glucose.

    Science.gov (United States)

    Azizi, Seyed Naser; Chaichi, Mohammad Javad; Shakeri, Parmis; Bekhradnia, Ahmadreza

    2015-07-05

    A novel fluorescence (FL) method using water-soluble CdSe quantum dots (QDs) is proposed for the fluorometric determination of hydrogen peroxide and glucose. Water-soluble CdSe QDs were synthesized by using thioglycolic acid as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy and transmission electron microscope (TEM). Ionic liquid-sensitized effect in aqueous solution was then investigated. In the presence of ionic liquid as catalyst, H2O2 was decomposed into radical that could quench the fluorescence of CdSe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdSe QDs by H2O2 producer with ionic liquid catalyst, which can be used to detect glucose. Therefore, a new FL analysis system was developed for the determination of glucose. Under the optimum conditions, there is a good linear relationship between the relative PL emission intensity and the concentration of glucose in the range of 5.0×10(-7)-1.0×10(-4) M of glucose with a correlation coefficient (R(2)) of 0.9973. The limit of detection of this system was found to be 1.0×10(-7) M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. Copyright © 2015. Published by Elsevier B.V.

  14. Radiation-Induced Fluidity and Glass-Liquid Transition in Irradiated Amorphous Materials

    International Nuclear Information System (INIS)

    Ojovan, M.I.

    2009-01-01

    This paper describes the fluidity behaviour of continuously irradiated glasses using the Congruent Bond Lattice model in which broken bonds 'configurons' facilitate the flow. Irradiation breaks the bonds creating configurons which at high concentrations provide the transition of material from the glassy to liquid state. An explicit equation of viscosity has been derived which gives results in agreement with experimental data. This equation provides correct viscosity data for non-irradiated materials and shows a significant increase of fluidity in radiation fields. It demonstrates a decrease of activation energy of flow for irradiated glasses. A simple equation for glass-transition temperature was also obtained which shows that irradiated glasses have lower glass transition temperatures and are readily transformed from glassy to liquid state e.g. fluidized in strong radiation fields. (authors)

  15. A Sensitive Validated Spectrophotometric Method for the Determination of Flucloxacillin Sodium

    Directory of Open Access Journals (Sweden)

    R. Singh Gujral

    2009-01-01

    Full Text Available A simple and sensitive spectrophotometric method has been proposed for the determination of flucloxacillin sodium. The determination method is based on charge transfer complexation reaction of the drug with iodine in methanol-dichloromethane medium. The absorbance was measured at 362 nm against the reagent blank. Under optimized experimental conditions, Beer's law is obeyed in the concentration ranges 1-9 μg/mL for flucloxacillin. The method was validated for specificity, linearity, precision, accuracy. The degree of linearity of the calibration curves, the percent recoveries, limit of detection and quantitation for the spectrophotometric method were determined. No interferences could be observed from the additives commonly present in the pharmaceutical formulations. The method was successfully applied for in vitro determination of human urine samples with low RSD value. This is simple, specific, accurate and sensitive spectrophotometric method.

  16. Even a Chronic Mild Hyperglycemia Affects Membrane Fluidity and Lipoperoxidation in Placental Mitochondria in Wistar Rats

    Science.gov (United States)

    Figueroa-García, María del Consuelo; Espinosa-García, María Teresa; Martinez-Montes, Federico; Palomar-Morales, Martín; Mejía-Zepeda, Ricardo

    2015-01-01

    It is known the deleterious effects of diabetes on embryos, but the effects of diabetes on placenta and its mitochondria are still not well known. In this work we generated a mild hyperglycemia model in female wistar rats by intraperitoneal injection of streptozotocin in 48 hours-old rats. The sexual maturity onset of the female rats was delayed around 6–7 weeks and at 16 weeks-old they were mated, and sacrificed at day 19th of pregnancy. In placental total tissue and isolated mitochondria, the fatty acids composition was analyzed by gas chromatography, and lipoperoxidation was measured by thiobarbituric acid reactive substances. Membrane fluidity in mitochondria was measured with the excimer forming probe dipyrenylpropane and mitochondrial function was measured with a Clark-type electrode. The results show that even a chronic mild hyperglycemia increases lipoperoxidation and decreases mitochondrial function in placenta. Simultaneously, placental fatty acids metabolism in total tissue is modified but in a different way than in placental mitochondria. Whereas the chronic mild hyperglycemia induced a decrease in unsaturated to saturated fatty acids ratio (U/S) in placental total tissue, the ratio increased in placental mitochondria. The measurements of membrane fluidity showed that fluidity of placenta mitochondrial membranes increased with hyperglycemia, showing consistency with the fatty acids composition through the U/S index. The thermotropic characteristics of mitochondrial membranes were changed, showing lower transition temperature and activation energies. All of these data together demonstrate that even a chronic mild hyperglycemia during pregnancy of early reproductive Wistar rats, generates an increment of lipoperoxidation, an increase of placental mitochondrial membrane fluidity apparently derived from changes in fatty acids composition and consequently, mitochondrial malfunction. PMID:26630275

  17. Rapid and sensitive enzymatic-radiochemical assay for the determination of triglycerides

    International Nuclear Information System (INIS)

    Khoo, J.C.; Miller, E.; Goldberg, D.I.

    1987-01-01

    An enzymatic-radiochemical method suitable for the determination of triglyceride levels of cells in culture is described. The method is based on the enzymatic hydrolysis of triglycerides to free fatty acids which then complex with 63 Ni. The method is rapid, accurate, and inexpensive. The procedure extends the sensitivity of triglyceride measurement to as low as 0.25 nanomoles

  18. Differential antibiotic sensitivity determined by the large ribosomal subunit in thermophilic archaea.

    OpenAIRE

    Ruggero, D; Londei, P

    1996-01-01

    Hybrid ribosomes obtained by mixing the ribosomal subunits of the extremely thermophilic archaea Sulfolobus solfataricus and Desulfurococcus mobilis were tested for their sensitivity to selected antibiotics. It is shown that structural differences in the large ribosomal subunits determine qualitatively and quantitatively the patterns of response to alpha-sarcin and paromomycin in these species.

  19. Determining pancreatic β-cell compensation for changing insulin sensitivity using an oral glucose tolerance test

    DEFF Research Database (Denmark)

    Solomon, Thomas; Malin, Steven K; Karstoft, Kristian

    2014-01-01

    Plasma glucose, insulin, and C-peptide responses during an OGTT are informative for both research and clinical practice in type 2 diabetes. The aim of this study was to use such information to determine insulin sensitivity and insulin secretion so as to calculate an oral glucose disposition index...

  20. Lipid fluidity at different regions in LDL and HDL of β-thalassemia/Hb E patients

    International Nuclear Information System (INIS)

    Morales, Noppawan Phumala; Charlermchoung, Chalermkhwan; Luechapudiporn, Rataya; Yamanont, Paveena; Fucharoen, Suthat; Chantharaksri, Udom

    2006-01-01

    Atherosclerosis-related vascular complications in β-thalassemia/hemoglobin E (β-thal/Hb E) patients may result from iron induced oxidation of lipoproteins. To identify the specific site of oxidative damage, changes in lipid fluidity at different regions in LDL and HDL particle were investigated using two fluorescence probes and two ESR spin probes. The magnitude of increased lipid fluidity in thalassemic lipoproteins was dependent on the location of the probes. In hydrophobic region, the rotational correlation times for 16-doxyl stearic acid and DPH anisotropy were markedly changed in LDL and HDL of the patients. In the surface region, there was only a slight change in the order parameter (S) for 5-doxyl stearic acid and TMA-DPH anisotropy. Lipid fluidity at the core of LDL and HDL showed good correlation with oxidative stress markers, the ratio of CL/CO, and the level of α-tocopherol, suggesting that hydrophobic region of thalassemic lipoprotein was a target site for oxidative damage

  1. Influence of nanoparticle-membrane electrostatic interactions on membrane fluidity and bending elasticity.

    Science.gov (United States)

    Santhosh, Poornima Budime; Velikonja, Aljaž; Perutkova, Šarka; Gongadze, Ekaterina; Kulkarni, Mukta; Genova, Julia; Eleršič, Kristina; Iglič, Aleš; Kralj-Iglič, Veronika; Ulrih, Nataša Poklar

    2014-02-01

    The aim of this work is to investigate the effect of electrostatic interactions between the nanoparticles and the membrane lipids on altering the physical properties of the liposomal membrane such as fluidity and bending elasticity. For this purpose, we have used nanoparticles and lipids with different surface charges. Positively charged iron oxide (γ-Fe2O3) nanoparticles, neutral and negatively charged cobalt ferrite (CoFe2O4) nanoparticles were encapsulated in neutral lipid 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine lipid mixture. Membrane fluidity was assessed through the anisotropy measurements using the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Though the interaction of both the types of nanoparticles reduced the membrane fluidity, the results were more pronounced in the negatively charged liposomes encapsulated with positively charged iron oxide nanoparticles due to strong electrostatic attractions. X-ray photoelectron spectroscopy results also confirmed the presence of significant quantity of positively charged iron oxide nanoparticles in negatively charged liposomes. Through thermally induced shape fluctuation measurements of the giant liposomes, a considerable reduction in the bending elasticity modulus was observed for cobalt ferrite nanoparticles. The experimental results were supported by the simulation studies using modified Langevin-Poisson-Boltzmann model. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. Effects of Insecticides on the Fluidity of Mitochondrial Membranes of the Diamondback Moth, Plutella xylostella, Resistant and Susceptible to Avermectin

    Science.gov (United States)

    Hu, J.; Liang, P.; Shi, X.; Gao, X.

    2008-01-01

    The effects of various insecticides on the fluidity of mitochondrial membranes and cross-resistance were investigated in the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) using strains that were both resistant and susceptible to avermectin. The resistant strain of P. xylostella, AV-R, developed 1078-fold resistance to avermetins with a high level of cross-resistance to the analogs of avermectins, ivermectin and emamectin benzoate. It had more than 1000 times greater resistance when compared with the avermectin-susceptible strain, XH-S. Mitochondrial membrane fluidity was measured by detecting fluorescence polarization using DPH (1,6-Diphenyl -1,3,5-hexatriene) as the fluorescence probe. Abamectin, emamectin benzoate, ivermectin, cypermethrin and fenvalerate decreased the fluidity of mitochondrial membranes in the XH-S strain at 25°C. However, fipronil and acephate did not change the fluidity of mitochondrial membrane when the concentration of these insecticides was 1×10-4 mol/L. Membrane fluidity increased as the temperature increased. The thermotropic effect on the polarization value of DPH increased as the insecticide concentration was increased. There was a significant difference of mitochondrial membrane fluidity between both XH-S and AV-R when temperature was less than 25°C and no difference was observed when the temperature was more than 25°C. The low-dose abamectin (0.11 mg/L) in vivo treatment caused a significant change of membrane fluidity in the XH-S strain and no change in the AV-R strain. However, a high-dose abamectin (11.86 mg/L) resulted in 100% mortality of the XH-S strain. In vivo treatment may cause a significant change of membrane fluidity in the AV-R strain PMID:20345311

  3. Epicutaneous aeroallergen sensitization in atopic dermatitis infants - determining the role of epidermal barrier impairment.

    Science.gov (United States)

    Boralevi, F; Hubiche, T; Léauté-Labrèze, C; Saubusse, E; Fayon, M; Roul, S; Maurice-Tison, S; Taïeb, A

    2008-02-01

    Sensitization to atopens is an early phenomenon that overlaps with the onset of atopic dermatitis (AD) in infancy. Early epidermal barrier impairment may facilitate the epicutaneous penetration of atopens. To correlate transepidermal water loss (TEWL) and aeroallergen sensitization in infants with AD. In this cross-sectional study we enrolled 59 AD children and 30 controls aged 3-12 months. Transepidermal water loss in uninvolved skin, specific immunoglobulin E, atopy patch test (APT) and skin prick tests were performed with respect to seven aeroallergens, i.e., Dermatophagoides pteronyssinus, D. farinae, cat, dog, birch pollen, ambrosia, and cockroach. Environmental conditions were assessed by a questionnaire, and the house dust mite (HDM) concentration was determined in dust samples. Eighty-nine percent of AD infants had a positive APT vs one out of eleven controls. AD infants had a significantly higher mean TEWL than controls (27.4 vs 11.1 g/m(2)/h, P cats, and dogs at home. This study confirms the high prevalence of delayed sensitization to indoor and outdoor aeroallergens in AD infants, and shows that the higher the TEWL, the higher the prevalence of sensitization to aeroallergens. These data are in favor of a major role of a constitutive epidermal barrier impairment in determining early atopen sensitization in infants with AD.

  4. A simple and sensitive method for determination of Norfloxacin in pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Zhuo Ye

    2015-06-01

    Full Text Available In this approach, a new voltammetric method for determination of norfloxacin was proposed with high sensitivity and wider detection linear range. The used voltammetric sensor was fabricated simply by coating a layer of graphene oxide (GO and Nafion composited film on glassy carbon electrode. The advantage of proposed method was sensitive electrochemical response for norfloxacin, which was attributed to the excellent electrical conductivity of GO and the accumulating function of Nafion under optimum experimental conditions, the present method revealed a good linear response for determination of norfloxacin in the range of 1×10-8mol/L-7×10-6 mol/L with a detection limit of 5×10-9 mol/L. The proposed method was successfully applied in the determination of norfloxacin in capsules with satisfactory results.

  5. Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

    Directory of Open Access Journals (Sweden)

    JELENA J. SAVOVIC

    2001-08-01

    Full Text Available Two atomizers were compared: an N2O–C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

  6. Position-Sensitive Detector with Depth-of-Interaction Determination for Small Animal PET

    CERN Document Server

    Fedorov, A; Kholmetsky, A L; Korzhik, M V; Lecoq, P; Lobko, A S; Missevitch, O V; Tkatchev, A

    2002-01-01

    Crystal arrays made of LSO and LuAP crystals 2x2x10 mm pixels were manufactured for evaluation of detector with depth-of-interaction (DOI) determination capability intended for small animal positron emission tomograph. Position-sensitive LSO/LuAP phoswich DOI detector based on crystal 8x8 arrays and HAMAMATSU R5900-00-M64 position-sensitive multi-anode photomultiplier tube was developed and evaluated. Time resolution was found to be not worse than 1.0 ns FWHM for both layers, and spatial resolution mean value was 1.5 mm FWHM for the center of field-of-view.

  7. Development of a localized probabilistic sensitivity method to determine random variable regional importance

    International Nuclear Information System (INIS)

    Millwater, Harry; Singh, Gulshan; Cortina, Miguel

    2012-01-01

    There are many methods to identify the important variable out of a set of random variables, i.e., “inter-variable” importance; however, to date there are no comparable methods to identify the “region” of importance within a random variable, i.e., “intra-variable” importance. Knowledge of the critical region of an input random variable (tail, near-tail, and central region) can provide valuable information towards characterizing, understanding, and improving a model through additional modeling or testing. As a result, an intra-variable probabilistic sensitivity method was developed and demonstrated for independent random variables that computes the partial derivative of a probabilistic response with respect to a localized perturbation in the CDF values of each random variable. These sensitivities are then normalized in absolute value with respect to the largest sensitivity within a distribution to indicate the region of importance. The methodology is implemented using the Score Function kernel-based method such that existing samples can be used to compute sensitivities for negligible cost. Numerical examples demonstrate the accuracy of the method through comparisons with finite difference and numerical integration quadrature estimates. - Highlights: ► Probabilistic sensitivity methodology. ► Determines the “region” of importance within random variables such as left tail, near tail, center, right tail, etc. ► Uses the Score Function approach to reuse the samples, hence, negligible cost. ► No restrictions on the random variable types or limit states.

  8. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J.A.M. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)], E-mail: a.miranda@portugalmail.pt; Sarmento, S. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Alves, P.; Torres, M.C. [Departamento de Fisica da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Bastos, A.L. [Servico de Medicina Nuclear, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Ponte, F. [Servico de Fisica Medica, Instituto Portugues de Oncologia Francisco Gentil do Porto, E.P.E., Rua Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)

    2008-01-15

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector.

  9. Single-acquisition method for simultaneous determination of extrinsic gamma-camera sensitivity and spatial resolution

    International Nuclear Information System (INIS)

    Santos, J.A.M.; Sarmento, S.; Alves, P.; Torres, M.C.; Bastos, A.L.; Ponte, F.

    2008-01-01

    A new method for measuring simultaneously both the extrinsic sensitivity and spatial resolution of a gamma-camera in a single planar acquisition was implemented. A dual-purpose phantom (SR phantom; sensitivity/resolution) was developed, tested and the results compared with other conventional methods used for separate determination of these two important image quality parameters. The SR phantom yielded reproducible and accurate results, allowing an immediate visual inspection of the spatial resolution as well as the quantitative determination of the contrast for six different spatial frequencies. It also proved to be useful in the estimation of the modulation transfer function (MTF) of the image formation collimator/detector system at six different frequencies and can be used to estimate the spatial resolution as function of the direction relative to the digital matrix of the detector

  10. Hessian matrix approach for determining error field sensitivity to coil deviations

    Science.gov (United States)

    Zhu, Caoxiang; Hudson, Stuart R.; Lazerson, Samuel A.; Song, Yuntao; Wan, Yuanxi

    2018-05-01

    The presence of error fields has been shown to degrade plasma confinement and drive instabilities. Error fields can arise from many sources, but are predominantly attributed to deviations in the coil geometry. In this paper, we introduce a Hessian matrix approach for determining error field sensitivity to coil deviations. A primary cost function used for designing stellarator coils, the surface integral of normalized normal field errors, was adopted to evaluate the deviation of the generated magnetic field from the desired magnetic field. The FOCUS code (Zhu et al 2018 Nucl. Fusion 58 016008) is utilized to provide fast and accurate calculations of the Hessian. The sensitivities of error fields to coil displacements are then determined by the eigenvalues of the Hessian matrix. A proof-of-principle example is given on a CNT-like configuration. We anticipate that this new method could provide information to avoid dominant coil misalignments and simplify coil designs for stellarators.

  11. Selective and sensitive determination of lactose in low-lactose dairy products with HPAEC-PAD.

    Science.gov (United States)

    van Scheppingen, Wibo B; van Hilten, Piet H; Vijverberg, Marieke P; Duchateau, Alexander L L

    2017-08-15

    The demand for low lactose dairy products is increasing and more different lactose free food is commercially available. The level of lactose in these products decreased during the last years and nowadays a concentration of lactose free". For the determination of the lactose concentrations in these dairy products a sensitive analysis method is needed. We developed a method for the determination of low concentrations of lactose in a wide range of dairy products. A simple sample preparation with dilution, centrifugation and ultrafiltration is efficient for the isolation of lactose from the sample matrix. In this paper, a new HPAEC-PAD analysis on a CarboPac PA100 column gives a good separation of lactose from the other saccharides. This separation in combination with the PAD detector yields a selective and sensitive method for the quantification at the desired concentrations of lactose in low lactose dairy products. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  12. A nanosilver-based spectrophotometry method for sensitive determination of tartrazine in food samples.

    Science.gov (United States)

    Sahraei, R; Farmany, A; Mortazavi, S S

    2013-06-01

    A new method is reported for sensitive determination of tartrazine in the food samples. The method is based on the catalytic effect of silver nanoparticle (AgNPs) on the oxidation reaction of tartrazine by potassium iodate in the acetate buffer medium. The reaction is followed spectrophotometrically by measuring the change in absorbance (ΔA) at 420 nm using a fixed time method (70 s). The reaction variables were optimised in order to achieve the highest sensitivity. The thirty six criterion detection limit was 0.3 ng/mL, and the relative standard deviation for ten replicate measurements of 30 ng/mL of tartrazine was 0.98% (n=10). The method was successfully applied to the determination of tartrazine in lemon, and papaya-flavoured gelatin, candy, and in fruit syrup. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Sensitivity and Specificity of Procalcitonin to Determine Etiology of Diarrhea in Children Younger Than 5 Years

    OpenAIRE

    Ismaili-Jaha, Vlora; Shala, Mujë; Azemi, Mehmedali; Spahiu, Shqipe; Hoxha, Teuta; Avdiu, Muharrem; Spahiu, Lidvana

    2014-01-01

    Aim: The aim of this study is to assess the sensitivity and specificity of procalcitonin to determine bacterial etiology of diarrhea. The examinees and methods: For this purpose we conducted the study comprising 115 children aged 1 to 60 months admitted at the Department of Pediatric Gastroenterology, Pediatric Clinic, divided in three groups based on etiology of the diarrhea that has been confirmed with respective tests during the hospitalization. Each group has equal number of patients – 35...

  14. Determination of aerodynamic sensitivity coefficients in the transonic and supersonic regimes

    Science.gov (United States)

    Elbanna, Hesham M.; Carlson, Leland A.

    1989-01-01

    The quasi-analytical approach is developed to compute airfoil aerodynamic sensitivity coefficients in the transonic and supersonic flight regimes. Initial investigation verifies the feasibility of this approach as applied to the transonic small perturbation residual expression. Results are compared to those obtained by the direct (finite difference) approach and both methods are evaluated to determine their computational accuracies and efficiencies. The quasi-analytical approach is shown to be superior and worth further investigation.

  15. Sensitive double-antibody method for simultaneous determination of insulin and growth hormone

    International Nuclear Information System (INIS)

    Koparanova, O.; Sotirov, G.; Tyrkolev, N.

    1982-01-01

    A method is described for simultaneous determination of insulin and growth hormone in one sample, using double-antibody technique. The method is characterized by appreciable sensitivity (2.5 μE/ml for insulin and a.2 ng/ml for growth hormone), exactness (variation quotient 6-16 per cent) and reproducibility (96.9-117 per cent). There was no statistically significant difference in the insulin and growth hormone values of the same sera, determined by the here suggested and the standard methods. The necessary test material for examination of either hormone is minimal (0.2 ml). One may thus extend the possibilities for radioimmunologic determination of insulin and growth hormone, when only minor amounts of serum or other biological fluid are available. The method is also less time consuming. Results are reported of statistical processing of an experimental model and different sera determined by the standard method and the one described by the authors. (author)

  16. Drought timing and local climate determine the sensitivity of eastern temperate forests to drought.

    Science.gov (United States)

    D'Orangeville, Loïc; Maxwell, Justin; Kneeshaw, Daniel; Pederson, Neil; Duchesne, Louis; Logan, Travis; Houle, Daniel; Arseneault, Dominique; Beier, Colin M; Bishop, Daniel A; Druckenbrod, Daniel; Fraver, Shawn; Girard, François; Halman, Joshua; Hansen, Chris; Hart, Justin L; Hartmann, Henrik; Kaye, Margot; Leblanc, David; Manzoni, Stefano; Ouimet, Rock; Rayback, Shelly; Rollinson, Christine R; Phillips, Richard P

    2018-02-20

    Projected changes in temperature and drought regime are likely to reduce carbon (C) storage in forests, thereby amplifying rates of climate change. While such reductions are often presumed to be greatest in semi-arid forests that experience widespread tree mortality, the consequences of drought may also be important in temperate mesic forests of Eastern North America (ENA) if tree growth is significantly curtailed by drought. Investigations of the environmental conditions that determine drought sensitivity are critically needed to accurately predict ecosystem feedbacks to climate change. We matched site factors with the growth responses to drought of 10,753 trees across mesic forests of ENA, representing 24 species and 346 stands, to determine the broad-scale drivers of drought sensitivity for the dominant trees in ENA. Here we show that two factors-the timing of drought, and the atmospheric demand for water (i.e., local potential evapotranspiration; PET)-are stronger drivers of drought sensitivity than soil and stand characteristics. Drought-induced reductions in tree growth were greatest when the droughts occurred during early-season peaks in radial growth, especially for trees growing in the warmest, driest regions (i.e., highest PET). Further, mean species trait values (rooting depth and ψ 50 ) were poor predictors of drought sensitivity, as intraspecific variation in sensitivity was equal to or greater than interspecific variation in 17 of 24 species. From a general circulation model ensemble, we find that future increases in early-season PET may exacerbate these effects, and potentially offset gains in C uptake and storage in ENA owing to other global change factors. © 2018 John Wiley & Sons Ltd.

  17. Sensitive spectrophotometric methods for determination of some organophosphorus pesticides in vegetable samples

    Directory of Open Access Journals (Sweden)

    MAGDA A. AKL

    2010-03-01

    Full Text Available Three rapid, simple, reproducible and sensitive spectrophotometric methods (A, B and C are described for the determination of two organophosphorus pesticides, (malathion and dimethoate in formulations and vegetable samples. The methods A and B involve the addition of an excess of Ce4+ into sulphuric acid medium and the determination of the unreacted oxidant by decreasing the red color of chromotrope 2R (C2R at a suitable lmax = 528 nm for method A, or a decrease in the orange pink color of rhodamine 6G (Rh6G at a suitable lmax = = 525 nm. The method C is based on the oxidation of malathion or dimethoate with the slight excess of N-bromosuccinimide (NBS and the determination of unreacted oxidant by reacting it with amaranth dye (AM in hydrochloric acid medium at a suitable lmax = 520 nm. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.1-4.2 μg mL−1. The apparent molar absorptivity, Sandell sensitivity, the detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration ranges are 0.25-4.0 μg mL−1. The developed methods were successfully applied to the determination of malathion, and dimethoate in their formulations and environmental vegetable samples.

  18. A sensitive fluorescence quenching method for determination of bismuth with tiron

    Energy Technology Data Exchange (ETDEWEB)

    Taher, Mohammad Ali; Rahimi, Mina [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Fazelirad, Hamid, E-mail: hamidfazelirad@gmail.com [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Department of Chemistry, Science and Research Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Young Researchers Society, Shahid Bahonar University of Kerman, P.O. Box 76175-133, Kerman (Iran, Islamic Republic of)

    2014-01-15

    We describe a fluorescence quenching method for determination of bismuth with tiron. The method is based on the reaction of tiron by bismuth(III) in acidic media. The influence of variables such as the pH, type of buffer, tiron concentration, reaction time and temperature were investigated. Under optimized conditions, the fluorescence quenching extent is proportional to the concentration of bismuth for Bi–tiron system at the range 0.13–2.09 μg mL{sup −1} and the detection limit is 0.05 μg mL{sup −1}. The proposed sensor presented good repeatability, evaluated in terms of relative standard deviation (R.S.D.=±0.498%) for 11 replicates. This sensitive, rapid and accurate method has been successfully applied to the determination of trace bismuth(III) in water and hair samples and certified reference materials. -- Highlights: • No previous paper report on use of fluorescence quenching for determination of Bi. • Fluorescence quenching of trion is a sensitive method for determination of Bi(III). • Under the optimum conditions the detection limit is very low (0.05 μg mL{sup −1}). • The procedure is simple and safe and has high tolerance limit to interferences.

  19. Water droplets' internal fluidity during horizontal motion on a superhydrophobic surface with an external electric field.

    Science.gov (United States)

    Sakai, Munetoshi; Kono, Hiroki; Nakajima, Akira; Sakai, Hideki; Abe, Masahiko; Fujishima, Akira

    2010-02-02

    On a superhydrophobic surface, the internal fluidity of water droplets with different volumes (15, 30 microL) and their horizontal motion in an external electric field were evaluated using particle image velocimetry (PIV). For driving of water droplets on a superhydrophobic coating between parallel electrodes, it was important to place them at appropriate positions. Droplets moved with slipping. Small droplets showed deformation that is more remarkable. Results show that the dielectrophoretic force induced the initial droplet motion and that the surface potential gradient drove the droplets after reaching the middle point between electrodes.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-01-01

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

  1. Influence of zinc deficiency on cell-membrane fluidity in Jurkat, 3T3 and IMR-32 cells.

    Science.gov (United States)

    Verstraeten, Sandra V; Zago, M Paola; MacKenzie, Gerardo G; Keen, Carl L; Oteiza, Patricia I

    2004-01-01

    We investigated whether zinc deficiency can affect plasma membrane rheology. Three cell lines, human leukaemia T-cells (Jurkat), rat fibroblasts (3T3) and human neuroblastoma cells (IMR-32), were cultured for 48 h in control medium, in zinc-deficient medium (1.5 microM zinc; 1.5 Zn), or in the zinc-deficient medium supplemented with 15 microM zinc (15 Zn). The number of viable cells was lower in the 1.5 Zn group than in the control and 15 Zn groups. The frequency of apoptosis was higher in the 1.5 Zn group than in the control and 15 Zn groups. Membrane fluidity was evaluated using the 6-(9-anthroyloxy)stearic acid and 16-(9-anthroyloxy)palmitic acid probes. Membrane fluidity was higher in 1.5 Zn cells than in the control cells; no differences were observed between control cells and 15 Zn cells. The effect of zinc deficiency on membrane fluidity at the water/lipid interface was associated with a higher phosphatidylserine externalization. The higher membrane fluidity in the hydrophobic region of the bilayer was correlated with a lower content of arachidonic acid. We suggest that the increased fluidity of the membrane secondary to zinc deficiency is in part due to a decrease in arachidonic acid content and the apoptosis-related changes in phosphatidylserine distribution. PMID:14629198

  2. Sensitivity analysis of an experimental methodology to determine radionuclide diffusion coefficients in granite

    International Nuclear Information System (INIS)

    Alonso, U.; Missana, T.; Garcia-Gutierrez, M.; Patelli, A.; Rigato, V.

    2005-01-01

    Full text of publication follows: The long-term quantitative analysis of the migration behaviour of the relevant radionuclides (RN) within the geological barrier of a radioactive waste repository requires, amongst other data, the introduction of reliable transport parameters, as diffusion coefficients. Since the determination of diffusion coefficients within crystalline rocks is complex and requires long experimental times even for non-sorbing radionuclides, the data available in the literature are very scarce. The nuclear ion beam technique RBS (Rutherford Backscattering Spectrometry) that is successfully used to determine diffusion profiles in thin film science is here examined as possible suitable technique to determine the diffusion coefficients of different RN within granite. As first step, the technique sensitivity and limitations to analyse diffusion coefficients in granite samples is evaluated, considering that the technique is especially sensitive to heavy elements. The required experimental conditions in terms of experimental times, concentration and methodology of analysis are discussed. The diffusants were selected accounting the RBS sensitivity but also trying to cover different behaviours of critical RN and a wide range of possible oxidation states. In particular, Cs(I) was chosen as representative fission product, while as relevant actinides or homologues, the diffusion of Th(IV), U(IV) and Eu (III) was studied. The diffusion of these above-mentioned cations is compared to the diffusion of Re, and I as representative of anionic species. The methodology allowed evaluating diffusion coefficients in the granite samples and, for most of the elements, the values obtained are in agreement with the values found in the literature. The diffusion coefficients calculated ranged from 10 -13 to 10 -16 m 2 /s. It is remarkable that the RBS technique is especially promising to determine diffusion coefficients of high-sorbing RN and it is applicable to a wide range

  3. What does the closure of context-sensitive constraints mean for determinism, autonomy, self-determination, and agency?

    Science.gov (United States)

    Juarrero, Alicia

    2015-12-01

    The role of context-sensitive constraints - first as enablers of complexification and subsequently as regulators that maintain the integrity of self-organized, coherent wholes - has only recently begun to be examined. Conceptualizing such organizational constraints in terms of the operations of far from equilibrium, nonlinear dynamic processes rekindles old metaphysical discussions concerning primary and secondary relations, emergence, causality, and the logic of explanation. In particular, far-from-equilibrium processes allow us to rethink how parts-to-whole and whole-to-parts - so-called "mereological"- relationships are constituted. A renewed understanding of recursive feedback and the role context-dependence plays in generating the boundary conditions and the internal organization of complex adaptive systems in turn allows us to redescribe formal and final cause in such a way as to provide a meaningful sense of heretofore seemingly intractable philosophical problems such as autonomy, self-determination, and agency. Copyright © 2015. Published by Elsevier Ltd.

  4. Evaluating Noise Sensitivity on the Time Series Determination of Lyapunov Exponents Applied to the Nonlinear Pendulum

    Directory of Open Access Journals (Sweden)

    L.F.P. Franca

    2003-01-01

    Full Text Available This contribution presents an investigation on noise sensitivity of some of the most disseminated techniques employed to estimate Lyapunov exponents from time series. Since noise contamination is unavoidable in cases of data acquisition, it is important to recognize techniques that could be employed for a correct identification of chaos. State space reconstruction and the determination of Lyapunov exponents are carried out to investigate the response of a nonlinear pendulum. Signals are generated by numerical integration of the mathematical model, selecting a single variable of the system as a time series. In order to simulate experimental data sets, a random noise is introduced in the signal. Basically, the analyses of periodic and chaotic motions are carried out. Results obtained from mathematical model are compared with the one obtained from time series analysis, evaluating noise sensitivity. This procedure allows the identification of the best techniques to be employed in the analysis of experimental data.

  5. Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

    NARCIS (Netherlands)

    Teunis, M.; Corsini, E.; Smits, M.; Madsen, C.B.; Eltze, T.; Ezendam, J.; Galbiati, V.; Gremmer, E.; Krul, C.A.M.; Landin, A.; Landsiedel, R.; Pieters, R.; Rasmussen, T.F.; Reinders, J.; Roggen, E.; Spiekstra, S.; Gibbs, S.

    2013-01-01

    At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers

  6. Determination of Some Cephalosporins in Pharmaceutical Formulations by a Simple and Sensitive Spectrofluorimetric Method

    Directory of Open Access Journals (Sweden)

    Ali Abdollahi, Ahad Bavili-Tabrizi

    2016-03-01

    Full Text Available Background: Cephalosporins are among the safest and the most effective broad-spectrum bactericidal antimicrobial agents which have been prescribed by the clinician as antibiotics. Thus, the developing of simple, sensitive and rapid analytical methods for their determination can be attractive and desirable. Methods: A simple, rapid and sensitive spectrofluorimetric method was developed for the determination of cefixime, cefalexin and ceftriaxone in pharmaceutical formulations. Proposed method is based on the oxidation of these cephalosporins with cerium (IV to produce cerium (III, and its fluorescence was monitored at 356 ± 3 nm after excitation at 254 ± 3 nm. Results: The variables effecting oxidation of each cephalosporin with cerum (IV were studied and optimized. Under the experimental conditions used, the calibration graphs were linear over the range 0.1-4 µg/mL. The limit of detection and limit of quantification were in the range 0.031-0.054 and 0.102-0.172 µg/mL, respectively. Intra- and inter-day assay precisions, expressed as the relative standard deviation (RSD, were lower than 5.6 and 6.8%, respectively. Conclusion: The proposed method was applied to the determination of studied cephalosporins in pharmaceutical formulations by good recoveries in the range 91-110%.

  7. Parameter studies to determine sensitivity of slug impact loads to properties of core surrounding structures

    International Nuclear Information System (INIS)

    Gvildys, J.

    1985-01-01

    A sensitivity study of the HCDA slug impact response of fast reactor primary containment to properties of core surrounding structures was performed. Parameters such as the strength of the radial shield material, mass, void, and compressibility properties of the gas plenum material, mass of core material, and mass and compressibility properties of the coolant were used as variables to determine the magnitude of the slug impact loads. The response of the reactor primary containment and the partition of energy were also given. A study was also performed using water as coolant to study the difference in slug impact loads

  8. The determination of self-powered neutron detector sensitivity on thermal and epithermal neutron flux densities

    International Nuclear Information System (INIS)

    Erben, O.

    1980-01-01

    The coefficients of thermal and epithermal neutron flux density depression and self-shielding for the SPN detectors with vanadium, rhodium, silver and cobalt emitters are presented, (for cobalt SPN detectors the functions describing the absorbtion of neutrons along the emitter cross-section are also shown). Using these coefficients and previously published beta particle escape efficiencies, sensitivities are determined for the principal types of detectors produced by Les Cables de Lyon and SODERN companies. The experiments and their results verifying the validity of the theoretical work are described. (author)

  9. Sensitivity of in vivo X-ray fluorescence determination of skeletal lead stores

    International Nuclear Information System (INIS)

    Sokas, R.K.; Besarab, A.; McDiarmid, M.A.; Shapiro, I.M.; Bloch, P.

    1990-01-01

    Eighteen patients with known past occupational lead exposure underwent parenteral diagnostic chelation with ethylenediaminetetraacetic acid and x-ray fluorescent determination of in vivo skeletal lead stores at the distal styloid process of the ulna and at the temporal base bone using a cobalt 57 source and measuring lead Ka x-rays. X-ray fluorescent lead measurements in both locations correlated with results of diagnostic chelation. Using a post-chelation urinary excretion of greater than 600 micrograms lead/24 h as the definition of high-lead stores, sensitivity of x-ray fluorescence at the wrist and temple was 56% and 39%, respectively

  10. Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

    International Nuclear Information System (INIS)

    Montiel, V. Ruiz-Valdepeñas; Campuzano, S.; Pellicanò, A.; Torrente-Rodríguez, R.M.; Reviejo, A.J.; Cosio, M.S.; Pingarrón, J.M.

    2015-01-01

    Highlights: • First amperometric magnetoimmunosensor for Ara h 1 determination. • Sensitive and selective detection of Ara h 1 in 2 h. • LOD of 6.3 ng mL −1 . • Determinations in food extracts and saliva. • Potential applicability in food safety and consumer protection. - Abstract: A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H 2 O 2 as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL −1 Ara h 1, a detection limit of 6.3 ng mL −1 , a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1

  11. Sensitive and selective magnetoimmunosensing platform for determination of the food allergen Ara h 1

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, V. Ruiz-Valdepeñas, E-mail: victor_lega90@hotmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Campuzano, S., E-mail: susanacr@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Pellicanò, A., E-mail: alessandro.pellicano@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Torrente-Rodríguez, R.M., E-mail: rebeca.magnolia@gmail.com [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Reviejo, A.J., E-mail: reviejo@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Cosio, M.S., E-mail: stella.cosio@unimi.it [Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan (Italy); Pingarrón, J.M., E-mail: pingarro@quim.ucm.es [Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2015-06-23

    Highlights: • First amperometric magnetoimmunosensor for Ara h 1 determination. • Sensitive and selective detection of Ara h 1 in 2 h. • LOD of 6.3 ng mL{sup −1}. • Determinations in food extracts and saliva. • Potential applicability in food safety and consumer protection. - Abstract: A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H{sub 2}O{sub 2} as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL{sup −1} Ara h 1, a detection limit of 6.3 ng mL{sup −1}, a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1.

  12. [The effects of electromagnetic pulse on fluidity and lipid peroxidation of mitochondrial membrane].

    Science.gov (United States)

    Wang, Changzhen; Cong, Jianbo; Xian, Hong; Cao, Xiaozhe; Sun, Cunpu; Wu, Ke

    2002-08-01

    To study the effects of intense electromagnetic pulse(EMP) on the biological effects of mitochondrial membrane. Rat liver mitochondrial suspension was exposed to EMP at 60 kV/m level. The changes of membrane lipid fluidity and membrane protein mobility were detected by ESR and spin label technique. Malondialdehyde(MDA) was detected by spectrophotometer. The mobility of membrane protein decreased significantly(P < 0.05). Correlation time (tau c) of control group was (0.501 +/- 0.077) x 10(-9)s, and tau c of EMP group was (0.594 +/- 0.049) x 10(-9)s, indicating that the mobility of protein was restricted. The fluidity of mitochondrial membrane increased significantly(P < 0.05) at the same time. Order parameter(S) of mitochondrial membrane lipid in control group was 0.63 +/- 0.01, while S of EMP group was 0.61 +/- 0.01(P < 0.05). MDA decreased significantly. The mobility and lipid peroxidation of mitochondrial membrane may be disturbed after EMP exposure.

  13. Numerical analysis of the thermal and fluid flow phenomena of the fluidity test

    Directory of Open Access Journals (Sweden)

    L. Sowa

    2010-01-01

    Full Text Available In the paper, two mathematical and numerical models of the metals alloy solidification in the cylindrical channel of fluidity test, which take into account the process of filling the mould cavity with molten metal, has been proposed. Velocity and pressure fields were obtained by solving the momentum equations and the continuity equation, while the thermal fields were obtained by solving the heat conduction equation containing the convection term. Next, the numerical analysis of the solidification process of metals alloy in the cylindrical mould channel has been made. In the models one takes into account interdependence of the thermal and dynamical phenomena. Coupling of the heat transfer and fluid flow phenomena has been taken into consideration by the changes of the fluidity function and thermophysical parameters of alloy with respect to the temperature. The influence of the velocity or the pressure and the temperature of metal pouring on the solid phase growth kinetics were estimated. The problem has been solved by the finite element method.

  14. Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence.

    Science.gov (United States)

    Sandor, Roman; Der, Christophe; Grosjean, Kevin; Anca, Iulia; Noirot, Elodie; Leborgne-Castel, Nathalie; Lochman, Jan; Simon-Plas, Françoise; Gerbeau-Pissot, Patricia

    2016-09-01

    Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  15. Not changes in membrane fluidity but proteotoxic stress triggers heat shock protein expression in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Rütgers, Mark; Muranaka, Ligia Segatto; Schulz-Raffelt, Miriam; Thoms, Sylvia; Schurig, Juliane; Willmund, Felix; Schroda, Michael

    2017-12-01

    A conserved reaction of all organisms exposed to heat stress is an increased expression of heat shock proteins (HSPs). Several studies have proposed that HSP expression in heat-stressed plant cells is triggered by an increased fluidity of the plasma membrane. Among the main lines of evidence in support of this model are as follows: (a) the degree of membrane lipid saturation was higher in cells grown at elevated temperatures and correlated with a lower amplitude of HSP expression upon a temperature upshift, (b) membrane fluidizers induce HSP expression at physiological temperatures, and (c) membrane rigidifier dimethylsulfoxide dampens heat-induced HSP expression. Here, we tested whether this holds also for Chlamydomonas reinhardtii. We show that heat-induced HSP expression in cells grown at elevated temperatures was reduced because they already contained elevated levels of cytosolic HSP70A/90A that apparently act as negative regulators of heat shock factor 1. We find that membrane rigidifier dimethylsulfoxide impaired translation under heat stress conditions and that membrane fluidizer benzyl alcohol not only induced HSP expression but also caused protein aggregation. These findings support the classical model for the cytosolic unfolded protein response, according to which HSP expression is induced by the accumulation of unfolded proteins. Hence, the membrane fluidity model should be reconsidered. © 2017 John Wiley & Sons Ltd.

  16. Determination of new electroweak parameters at the ILC. Sensitivity to new physics

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, M.; Schmidt, E.; Schroeder, H. [Rostock Univ. (Germany). Inst. fuer Physik; Kilian, W. [Siegen Univ. (Gesamthochschule) (Germany). Fach Physik]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Krstonosic, P.; Reuter, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Moenig, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2006-04-15

    We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multidimensional parameter fit of the set of anomalous couplings. The analysis does not rely on simplifying assumptions such as custodial symmetry or approximations such as the equivalence theorem. We supplement this by a similar new study of triple weak-boson production, which is sensitive to the same set of anomalous couplings. Including the known results on triple gauge couplings and oblique corrections, we thus quantitatively determine the indirect sensitivity of the ILC to new physics in the electroweak symmetry-breaking sector, conveniently parameterized by real or fictitious resonances in each accessible spin/isospin channel. (Orig.)

  17. Highly Sensitive Colorimetric Assay for Determining Fe3+ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

    Directory of Open Access Journals (Sweden)

    Kyungmin Kim

    2017-01-01

    Full Text Available A highly sensitive and simple colorimetric assay for the detection of Fe3+ ions was developed using gold nanoparticles (AuNPs conjugated with glycol chitosan (GC. The Fe3+ ion coordinates with the oxygen atoms of GC in a hexadentate manner (O-Fe3+-O, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the bound Fe3+ was coordinated to the oxygen atoms of the ethylene glycol in GC, which resulted in a significant color change from light red to dark midnight blue due to aggregation. Using this GC-AuNP probe, the quantitative determination of Fe3+ in biological, environmental, and pharmaceutical samples could be achieved by the naked eye and spectrophotometric methods. Sensitive response and pronounced color change of the GC-AuNPs in the presence of Fe3+ were optimized at pH 6, 70°C, and 300 mM NaCl concentration. The absorption intensity ratio (A700/A510 linearly correlated to the Fe3+ concentration in the linear range of 0–180 μM. The limits of detection were 11.3, 29.2, and 46.0 nM for tap water, pond water, and iron supplement tablets, respectively. Owing to its facile and sensitive nature, this assay method for Fe3+ ions can be applied to the analysis of drinking water and pharmaceutical samples.

  18. Determination of new electroweak parameters at the ILC. Sensitivity to new physics

    International Nuclear Information System (INIS)

    Beyer, M.; Schmidt, E.; Schroeder, H.; Krstonosic, P.; Reuter, J.; Moenig, K.

    2006-04-01

    We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multidimensional parameter fit of the set of anomalous couplings. The analysis does not rely on simplifying assumptions such as custodial symmetry or approximations such as the equivalence theorem. We supplement this by a similar new study of triple weak-boson production, which is sensitive to the same set of anomalous couplings. Including the known results on triple gauge couplings and oblique corrections, we thus quantitatively determine the indirect sensitivity of the ILC to new physics in the electroweak symmetry-breaking sector, conveniently parameterized by real or fictitious resonances in each accessible spin/isospin channel. (Orig.)

  19. Environmental context determines community sensitivity of freshwater zooplankton to a pesticide

    International Nuclear Information System (INIS)

    Stampfli, Nathalie C.; Knillmann, Saskia; Liess, Matthias; Beketov, Mikhail A.

    2011-01-01

    The environment is currently changing worldwide, and ecosystems are being exposed to multiple anthropogenic pressures. Understanding and consideration of such environmental conditions is required in ecological risk assessment of toxicants, but it remains basically limited. In the present study, we aimed to determine how and to what extent alterations in the abiotic and biotic environmental conditions can alter the sensitivity of a community to an insecticide, as well as its recovery after contamination. We conducted an outdoor microcosm experiment in which zooplankton communities were exposed to the insecticide esfenvalerate (0.03, 0.3, and 3 μg/L) under different regimes of solar radiation and community density, which represented different levels of food availability and competition. We focused on the sensitivity of the entire community and analysed it using multivariate statistical methods, such as principal response curves and redundancy analysis. The results showed that community sensitivity varied markedly between the treatments. In the experimental series with the lowest availability of food and strongest competition significant effects of the insecticide were found at the concentration of 0.03 μg/L. In contrast, in the series with relatively higher food availability and weak competition such effects were detected at 3 μg/L only. However, we did not find significant differences in the community recovery rates between the experimental treatments. These findings indicate that environmental context is more important for ecotoxicological evaluation than assumed previously.

  20. Religion and Sexual Identity Fluidity in a National Three-Wave Panel of U.S. Adults.

    Science.gov (United States)

    Scheitle, Christopher P; Wolf, Julia Kay

    2018-05-01

    Research has shown that cross-sectional estimates of sexual identities overlook fluidity in those identities. Research has also shown that social factors, such as competing identities, can influence sexual identity fluidity. We contributed to this literature in two ways. First, we utilized a representative panel of US adults (N = 1034) surveyed in 2010, 2012, and 2014 by the General Social Survey. The addition of a third observation allowed us to examine more complexity in sexual identity fluidity. We found that 2.40% of US adults reported at least one change in sexual identity across the 4 years, with 1.59% reporting one change and 0.81% reporting two changes. Our second contribution came from examining the role of religion, as past research has suggested that religion can destabilize and prolong sexual identity development. We found that lesbian or gay individuals (N = 17), bisexuals (N = 15), and females (N = 585) showed more sexual identity fluidity compared to heterosexuals (N = 1003) and males (N = 450), respectively. Marital status, age, race, and education did not have significant associations with sexual identity fluidity. Regarding the role of religion, we found that participants identifying as more religious in Wave 1 showed more fluidity in sexual identity across later observations. Further analysis showed that higher levels of religiosity make it more likely that lesbian or gay individuals will be fluid in sexual identity, but this is not the case for heterosexual individuals. This finding reinforces past qualitative research that has suggested that religion can extend or complicate sexual minorities' identity development.

  1. A molecular imprinted SPR biosensor for sensitive determination of citrinin in red yeast rice.

    Science.gov (United States)

    Atar, Necip; Eren, Tanju; Yola, Mehmet Lütfi

    2015-10-01

    A novel and sensitive molecular imprinted surface plasmon resonance (SPR) biosensor was developed for selective determination of citrinin (CIT) in red yeast rice. Firstly, the gold surface of SPR chip was modified with allyl mercaptane. Then, CIT-imprinted poly(2-hydroxyethyl methacrylate-methacryloylamidoglutamic acid) (p(HEMA-MAGA)) film was generated on the gold surface modified with allyl mercaptane. The unmodified and imprinted surfaces were characterized by Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and contact angle measurements. The linearity range and the detection limit were obtained as 0.005-1.0 ng/mL and 0.0017 ng/mL, respectively. The SPR biosensor was applied to determination of CIT in red yeast rice sample. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. High sensitive determination of zinc with novel water-soluble small molecular fluorescent sensor

    International Nuclear Information System (INIS)

    Weng Ying; Chen Zilin; Wang Fang; Xue Lin; Jiang Hua

    2009-01-01

    A high sensitive method of quantitative analysis for the determination of zinc in the nutrition supplements has been developed by using a novel water-soluble fluorescent sensor HQ3: (8-pyridylmethyloxy-2-methyl-quinoline). Under the optimized condition of 67 mM phosphate buffer, pH 7.4, and 5% (v/v) DMSO, the zinc concentration showed good linear relationship with fluorescence intensity in the range of 7.5 x 10 -8 to 2.5 x 10 -5 M with the detection limit of 1.5 x 10 -8 M. HQ3 exhibited high selectivity to zinc comparing with other metal ions except for cadmium. The developed analytical method was successfully used for determining the content of zinc in a real sample of zinc gluconate solution of Sanchine.

  3. Quantum dots (QDs) based fluorescence probe for the sensitive determination of kaempferol

    Science.gov (United States)

    Tan, Xuanping; Liu, Shaopu; Shen, Yizhong; He, Youqiu; Yang, Jidong

    2014-12-01

    In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552 nm against the concentration of KAE was observed in the range of 4-44 μg mL-1 with a detection limit (3σ/K) of 0.79 μg mL-1. In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

  4. Ex vivo stimulation of whole blood as a means to determine glucocorticoid sensitivity

    Directory of Open Access Journals (Sweden)

    Burnsides C

    2012-08-01

    Full Text Available Christopher Burnsides,1,* Jacqueline Corry,1,* Jacob Alexander,1 Catherine Balint,1 David Cosmar,1 Gary Phillips,2 Jeanette I Webster Marketon1,31Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Internal Medicine, 2Center for Biostatistics, 3Institute for Behavioral Medicine Research, Wexner Medical Center at The Ohio State University, Columbus, OH, USA*JC and CB have equally contributed to this workPurpose: Glucocorticoids are commonly prescribed to treat a number of diseases including the majority of inflammatory diseases. Despite considerable interpersonal variability in response to glucocorticoids, an insensitivity rate of about 30%, and the risk of adverse side effects of glucocorticoid therapy, currently no assay is performed to determine sensitivity.Patients and methods: Here we propose a whole blood ex vivo stimulation assay to interrogate known glucocorticoid receptor (GR up- and downregulated genes to indicate glucocorticoid sensitivity. We have chosen to employ real-time PCR in order to provide a relatively fast and inexpensive assay.Results: We show that the GR-regulated genes, GILZ and FKBP51, are upregulated in whole blood by treatment with dexamethasone and that LPS-induction of cytokines (IL-6 and TNFα are repressed by dexamethasone in a dose responsive manner. There is considerable interpersonal variability in the maximum induction of these genes but little variation in the EC50 and IC50 concentrations. The regulation of the GR-induced genes differs throughout the day whereas the suppression of LPS-induced cytokines is not as sensitive to time of day.Conclusion: In all, this assay would provide a method to determine glucocorticoid receptor responsiveness in whole blood.Keywords: glucocorticoid responsiveness, gene regulation, nuclear receptor, GILZ, FKBP51, cytokines

  5. Insulin Sensitivity Determines Effects of Insulin and Meal Ingestion on Systemic Vascular Resistance in Healthy Subjects.

    Science.gov (United States)

    Woerdeman, Jorn; Meijer, Rick I; Eringa, Etto C; Hoekstra, Trynke; Smulders, Yvo M; Serné, Erik H

    2016-01-01

    In addition to insulin's metabolic actions, insulin can dilate arterioles which increase blood flow to metabolically active tissues. This effect is blunted in insulin-resistant subjects. Insulin's effect on SVR, determined by resistance arterioles, has, however, rarely been examined directly. We determined the effects of both hyperinsulinemia and a mixed meal on SVR and its relationship with insulin sensitivity. Thirty-seven lean and obese women underwent a hyperinsulinemic-euglycemic clamp, and 24 obese volunteers underwent a mixed-meal test. SVR was assessed using CPP before and during hyperinsulinemia as well as before and 60 and 120 minutes after a meal. SVR decreased significantly during hyperinsulinemia (-13%; p Insulin decreased SVR more strongly in insulin-sensitive individuals (standardized β: -0.44; p = 0.01). In addition, SVR at 60 minutes after meal ingestion was inversely related to the Matsuda index (β: -0.39; p = 0.04) and the change in postprandial SVR was directly related to postprandial glycemia (β: 0.53; p insulin resistance. This suggests that resistance to insulin-induced vasodilatation contributes to regulation of vascular resistance. © 2015 John Wiley & Sons Ltd.

  6. The Significance of Ultrasound in Determining Whether SHPT Patients Are Sensitive to Calcitriol Treatment

    Directory of Open Access Journals (Sweden)

    Xing-xin Liang

    2016-01-01

    Full Text Available This study was to explore the significance of ultrasound in determining whether the patients with secondary hyperparathyroidism (SHPT are sensitive to calcitriol treatment. According to the decrease value of parathyroid hormone (PTH, 42 SHPT patients were divided into two groups: drug susceptible group and drug insusceptible group. These 42 SHPT patients’ ultrasound images were retrospectively analyzed. The morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands were correlated with drug therapeutic outcome (oral calcitriol. Most SHPT patients with drug susceptible showed volume <438.50 mm3 and number ≤2, with 0-1 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX <1.59 and elastic modulus <18.8 kPa, whereas most SHPT patients with drug insusceptible showed volume ≥438.50 mm3 and number ≥3, with 2-3 structural and vascular patterns, associated with Relative Maximum Intensity (RIMAX ≥1.59 and elastic modulus ≥18.8 kPa. Therefore, ultrasonography in SHPT allows an accurate definition of the morphology, size, number, blood flow, elastic modulus, and perfusion of the parathyroid glands and is useful in determining whether SHPT patients are sensitive to calcitriol treatment.

  7. Sensitive kinetic spectrophotometric determination of captopril and ethamsylate in pharmaceutical preparations and biological fluids.

    Science.gov (United States)

    El-Shabrawy, Y; El-Enany, N; Salem, K

    2004-10-01

    A highly sensitive kinetic spectrophotometric method was developed for the determination of captopril (CPL) and ethamsylate (ESL) in pharmaceutical preparations and biological fluids. The method is based on a catalytic acceleration of the reaction between sodium azide and iodine in an aqueous solution. Concentration range of 0.1-1.5 microg ml(-1) for CPL and 0.3-3 microg ml(-1) for ESL was determined by measuring the decrease in the absorbance of iodine at 348 nm by a fixed time method. The decrease in absorbance after 5 min was markedly correlated to the concentration. The relative standard deviations obtained were 1.30 and 1.87 for CPL and ESL, respectively, in pure forms. Correlation coefficients were 0.9997 and 0.9999 for CPL and ESL, respectively. The detection limits were determined as (S/N = 3) were 20 ng ml(-1) for CPL and 50 ng ml(-1) for ESL. The proposed procedure was successively applied for the determination of both drugs in pharmaceutical preparations and in biological fluids.

  8. Determination of Autoantibody Isotypes Increases the Sensitivity of Serodiagnostics in Rheumatoid Arthritis

    Directory of Open Access Journals (Sweden)

    Daniela Sieghart

    2018-04-01

    Full Text Available Anti-citrullinated protein antibodies (ACPA and rheumatoid factor (RF are the most commonly used diagnostic markers of rheumatoid arthritis (RA. These antibodies are predominantly of the immunoglobulin (Ig M (RF or IgG (ACPA isotype. Other subtypes of both antibodies—particularly IgA isotypes and other autoantibodies—such as RA33 antibodies—have been repeatedly reported but their diagnostic value has still not been fully elucidated. Here, we investigated the prevalence of IgA, IgG, and IgM subtypes of RF, ACPA, and RA33 antibodies in patients with RA. To determine the diagnostic specificity and sensitivity sera from 290 RA patients (165 early and 125 established disease, 261 disease controls and 100 healthy subjects were tested for the presence of IgA, IgG, and IgM isotypes of RF, ACPA, and RA33 by EliA™ platform (Phadia AB, Uppsala, Sweden. The most specific antibodies were IgG-ACPA, IgA-ACPA, and IgG-RF showing specificities >98%, closely followed by IgG- and IgA-RA33 while IgM subtypes were somewhat less specific, ranging from 95.8% (RA33 to 90% (RF. On the other hand, IgM-RF was the most sensitive subtype (65% followed by IgG-ACPA (59.5% and IgA-RF (50.7%. Other subtypes were less sensitive ranging from 35 (IgA-ACPA to 6% (IgA-RA33. RA33 antibodies as well as IgA-RF and IgA-ACPA were found to increase the diagnostic sensitivity of serological testing since they were detected also in seronegative patients reducing their number from 109 to 85. Moreover, analyzing IgM-RF by EliA™ proved more sensitive than measuring RF by nephelometry and further reduced the number of seronegative patients to 76 individuals. Importantly, among antibody positive individuals, RA patients were found having significantly more antibodies (≥3 than disease controls which generally showed one or two antibody species. Thus, increasing the number of autoantibodies in serological routine testing provides valuable additional information allowing to better

  9. Two-tiered keratinocyte assay: IL-18 production by NCTC2544 cells to determine the skin sensitizing capacity and an epidermal equivalent assay to determine sensitizer potency

    DEFF Research Database (Denmark)

    Teunis, Marc; Corsini, Emanuela; Smits, Mieke

    2012-01-01

    the use of animals. The aim of the EU FP6 Integrated Project Sens-it-iv was to develop and optimize an integrated testing strategy consisting of in vitro, human cell based assays which will closely mimic sensitization mechanisms in vivo. These assays should be an alternative approach to the LLNA. The NCTC...... method to the LLNA. Both assays are based on the use of human keratinocytes, which have been shown, over the last two decades, to play a key role in all phases of skin sensitization. First, 4 known chemicals were tested during a transferability study in which 6 laboratories participated. Three...

  10. [Sensitive determination of Bi3+ by spectrofluorimetry based on graphene oxide-methylene blue system].

    Science.gov (United States)

    Zhai, Qiu-ge; Guo, Peng; Zhou, Lin; Liu, Yan-ming

    2014-08-01

    Graphene oxide was prepared by the modified Hummers method and characterized by field emission scanning electron microscopy. The interaction of graphene with methylene blue was studied by UV absorption, the intensity of two main absorption peaks of methylene blue decreased significantly after the fluorescence was quenched, and the energy transfer didn't occur because the overlap of the absorption spectrum of GO and the emission spectrum of MB is too small. Therefore, the fluorescence quenching of MB and GO was static. When adding a certain amount of Bi3+ in the graphene-methylene blue system, Bi3+ replaces the methylene blue from the graphene-methylene blue complexes because Bi3+ has the smaller volume and is more positively charged. The methylene blue therefore dissociates from the GO-MB complexes, resulting in the recovery of fluorescence of the system. Furthermore, the fluorescence of the system increases with the increase in the amount of Bi3+ due to the enhanced amount of MB in the system. A novel spectrofluorimetric method was therefore developed for the sensitive determination of Bi3+. Some parameters including the concentration of methylene blue, the amount of graphene oxide, the amount of nitric acid and the sequence of reagent adding were optimized to obtain higher sensitivity. The fluorescence of the system was detected at an emission wavelength of 667 nm with excitation at 690 nm. Under the optimized conditions, the concentration of Bi3+ showed good linear relationships with the fluorescence intensity in the range of 0.5-100 micromol x L(-1), with correlation coefficients of r = 0.9955. The limits of detection for Bi3+ was 1.0 x 10(-8) mol x L(-1) (S/N=3). The selectivity of the proposed method was evaluated and the results showed that 1000-fold K+, Ca+, Na+, Mg2+, Cu2+; 100-fold Fe3+, Be2+, SiO2- Al3+, Ni2+, Sb3+, NO3-, Cl-, F-, and 20-fold Pb2+, Hg2+, Cd2+ had negligible interference with the determination of Bi3+. The method has advantages of

  11. Sensitive non-radioactive determination of aminotransferase stereospecificity for C-4' hydrogen transfer on the coenzyme.

    Science.gov (United States)

    Jomrit, Juntratip; Summpunn, Pijug; Meevootisom, Vithaya; Wiyakrutta, Suthep

    2011-02-25

    A sensitive non-radioactive method for determination of the stereospecificity of the C-4' hydrogen transfer on the coenzymes (pyridoxal phosphate, PLP; and pyridoxamine phosphate, PMP) of aminotransferases has been developed. Aminotransferase of unknown stereospecificity in its PLP form was incubated in (2)H(2)O with a substrate amino acid resulted in PMP labeled with deuterium at C-4' in the pro-S or pro-R configuration according to the stereospecificity of the aminotransferase tested. The [4'-(2)H]PMP was isolated from the enzyme protein and divided into two portions. The first portion was incubated in aqueous buffer with apo-aspartate aminotransferase (a reference si-face specific enzyme), and the other was incubated with apo-branched-chain amino acid aminotransferase (a reference re-face specific enzyme) in the presence of a substrate 2-oxo acid. The (2)H at C-4' is retained with the PLP if the aminotransferase in question transfers C-4' hydrogen on the opposite face of the coenzyme compared with the reference aminotransferase, but the (2)H is removed if the test and reference aminotransferases catalyze hydrogen transfer on the same face. PLP formed in the final reactions was analyzed by LC-MS/MS for the presence or absence of (2)H. The method was highly sensitive that for the aminotransferase with ca. 50 kDa subunit molecular weight, only 2mg of the enzyme was sufficient for the whole test. With this method, the use of radioactive substances could be avoided without compromising the sensitivity of the assay. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

    DEFF Research Database (Denmark)

    Teunis, Marc; Corsini, Emanuela; Smits, Mieke

    2013-01-01

    . The two tiered approach may offer an unique opportunity to provide an alternative method to the Local Lymph Node Assay (LLNA). These assays are both based on the use of human keratinocytes, which have been shown over the last two decades, to play a key role in all phases of skin sensitization....

  13. A High Sensitivity Micro Format Chemiluminescence Enzyme Inhibition Assay for Determination of Hg(II

    Directory of Open Access Journals (Sweden)

    Kanchanmala Deshpande

    2010-06-01

    Full Text Available A highly sensitive and specific enzyme inhibition assay based on alcohol oxidase (AlOx and horseradish peroxidase (HRP for determination of mercury Hg(II in water samples has been presented. This article describes the optimization and miniaturization of an enzymatic assay using a chemiluminescence reaction. The analytical performance and detection limit for determination of Hg(II was optimized in 96 well plates and further extended to 384 well plates with a 10-fold reduction in assay volume. Inhibition of the enzyme activity by dissolved Hg(II was found to be linear in the range 5–500 pg.mL−1 with 3% CVin inter-batch assay. Due to miniaturization of assay in 384 well plates, Hg(II was measurable as low as 1 pg.mL−1 within15 min. About 10-fold more specificity of the developed assay for Hg(II analysis was confirmed by challenging with interfering divalent metal ions such as cadmium Cd(II and lead Pb(II. Using the proposed assay we could successfully demonstrate that in a composite mixture of Hg(II, Cd(II and Pb(II, inhibition by each metal ion is significantly enhanced in the presence of the others. Applicability of the proposed assay for the determination of the Hg(II in spiked drinking and sea water resulted in recoveries ranging from 100–110.52%.

  14. Determination of paraquat in water samples using a sensitive fluorescent probe titration method.

    Science.gov (United States)

    Yao, Feihu; Liu, Hailong; Wang, Guangquan; Du, Liming; Yin, Xiaofen; Fu, Yunlong

    2013-06-01

    Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (deltaF) showed a good linear relationship with PQ concentrations from 1.0 x 10(-8) to 1.2 x 10(-5) mol/L with a detection limit of 3.35 x 10(-9) mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by 1H NMR spectroscopy.

  15. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J, E-mail: z.lu@sheffield.ac.uk, E-mail: s.j.matcher@sheffield.ac.uk [Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom)

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  16. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    International Nuclear Information System (INIS)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J

    2011-01-01

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  17. A Sensitive Photometric Procedure for Cobalt Determination in Water Employing a Compact Multicommuted Flow Analysis System.

    Science.gov (United States)

    da Silva Magalhães, Ticiane; Reis, Boaventura F

    2017-09-01

    In this work, a multicommuted flow analysis procedure is proposed for the spectrophotometric determination of cobalt in fresh water, employing an instrument setup of downsized dimension and improved cost-effectiveness. The method is based on the catalytic effect of Co(II) on the Tiron oxidation by hydrogen peroxide in alkaline medium, forming a complex that absorbs radiation at 425 nm. The photometric detection was accomplished using a homemade light-emitting-diode (LED)-based photometer designed to use a flow cell with an optical path-length of 100 mm to improve sensitivity. After selecting adequate values for the flow system variables, adherence to the Beer-Lambert-Bouguer law was observed for standard solution concentrations in the range of 0.13-1.5 µg L -1 Co(II). Other useful features including a relative standard deviation of 2.0% (n = 11) for a sample with 0.49 µg L -1 Co(II), a detection limit of 0.06 µg L -1 Co(II) (n = 20), an analytical frequency of 42 sample determinations per hour, and waste generation of 1.5 mL per determination were achieved.

  18. Sensitive time-resolved fluoroimmunoassay for quantitative determination of clothianidin in agricultural samples.

    Science.gov (United States)

    Li, Ming; Sheng, Enze; Yuan, Yulong; Liu, Xiaofeng; Hua, Xiude; Wang, Minghua

    2014-05-01

    Europium (Eu(3+))-labeled antibody was used as a fluorescent label to develop a highly sensitive time-resolved fluoroimmunoassay (TRFIA) for determination of clothianidin residues in agricultural samples. Toward this goal, the Eu(3+)-labeled polyclonal antibody and goat anti-rabbit antibody were prepared for developing and evaluating direct competitive TRFIA (dc-TRFIA) and indirect competitive TRFIA (ic-TRFIA). Under optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC10) of clothianidin were 9.20 and 0.0909 μg/L for the dc-TRFIA and 2.07 and 0.0220 μg/L for the ic-TRFIA, respectively. The ic-TRFIA has no obvious cross-reactivity with the analogues of clothianidin except for dinotefuran. The average recoveries of clothianidin from spiked water, soil, cabbage, and rice samples were estimated to range from 74.1 to 115.9 %, with relative standard deviations of 3.3 to 11.7 %. The results of TRFIA for the blind samples were largely consistent with gas chromatography (R (2) = 0.9902). The optimized ic-TRFIA might become a sensitive and satisfactory analytical method for the quantitative monitoring of clothianidin residues in agricultural samples.

  19. Determination of piroxicam in pharmaceutical formulations and urine samples using europium-sensitized luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Al-Kindy, Salma M.Z. [Department of Chemistry, College of Science, P.O. Box 36, Al-Khod 123, Sultan Qaboos University (Oman)], E-mail: alkindy@squ.edu.om; Suliman, Fakhr Eldin O.; Al-Wishahi, Aisha A.; Al-Lawati, Haidar A.J.; Aoudia, Muhammed [Department of Chemistry, College of Science, P.O. Box 36, Al-Khod 123, Sultan Qaboos University (Oman)

    2007-12-15

    A simple, selective and sensitive luminescence method for the assay of piroxicam (PX) in aqueous solution is developed. The method is based on the luminescence sensitization of europium (Eu{sup 3+}) by formation of ternary complex with PX in the presence of TOPO and Tween-80 as surfactant. The signal for Eu-PX-TOPO is monitored at {lambda}{sub ex}=359 nm and {lambda}{sub em}=615 nm. Optimum conditions for the formation of the complex in sequential injection analysis (SIA) were 0.01 M Tris buffer, pH 7.5, TOPO 5.0x10{sup -5} M, Tween-80 0.15% and 1.5 mM of Eu{sup 3+}, which allows the determination of 100-1000 ppb of PX with limit of detection (LOD) of 29 ppb. The relative standard deviations of the method range between 0.5% and 3.9% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assay of PX in pharmaceutical formulations and in urine samples. Average recoveries of 100.8{+-}1.7% was obtained in tablet, whereas a recovery of 97.5{+-}2.0% was obtained for the total PX (PX+hydoxy-PX) in urine sample.

  20. Detecting determinism with improved sensitivity in time series: rank-based nonlinear predictability score.

    Science.gov (United States)

    Naro, Daniel; Rummel, Christian; Schindler, Kaspar; Andrzejak, Ralph G

    2014-09-01

    The rank-based nonlinear predictability score was recently introduced as a test for determinism in point processes. We here adapt this measure to time series sampled from time-continuous flows. We use noisy Lorenz signals to compare this approach against a classical amplitude-based nonlinear prediction error. Both measures show an almost identical robustness against Gaussian white noise. In contrast, when the amplitude distribution of the noise has a narrower central peak and heavier tails than the normal distribution, the rank-based nonlinear predictability score outperforms the amplitude-based nonlinear prediction error. For this type of noise, the nonlinear predictability score has a higher sensitivity for deterministic structure in noisy signals. It also yields a higher statistical power in a surrogate test of the null hypothesis of linear stochastic correlated signals. We show the high relevance of this improved performance in an application to electroencephalographic (EEG) recordings from epilepsy patients. Here the nonlinear predictability score again appears of higher sensitivity to nonrandomness. Importantly, it yields an improved contrast between signals recorded from brain areas where the first ictal EEG signal changes were detected (focal EEG signals) versus signals recorded from brain areas that were not involved at seizure onset (nonfocal EEG signals).

  1. Determination of piroxicam in pharmaceutical formulations and urine samples using europium-sensitized luminescence

    International Nuclear Information System (INIS)

    Al-Kindy, Salma M.Z.; Suliman, Fakhr Eldin O.; Al-Wishahi, Aisha A.; Al-Lawati, Haidar A.J.; Aoudia, Muhammed

    2007-01-01

    A simple, selective and sensitive luminescence method for the assay of piroxicam (PX) in aqueous solution is developed. The method is based on the luminescence sensitization of europium (Eu 3+ ) by formation of ternary complex with PX in the presence of TOPO and Tween-80 as surfactant. The signal for Eu-PX-TOPO is monitored at λ ex =359 nm and λ em =615 nm. Optimum conditions for the formation of the complex in sequential injection analysis (SIA) were 0.01 M Tris buffer, pH 7.5, TOPO 5.0x10 -5 M, Tween-80 0.15% and 1.5 mM of Eu 3+ , which allows the determination of 100-1000 ppb of PX with limit of detection (LOD) of 29 ppb. The relative standard deviations of the method range between 0.5% and 3.9% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assay of PX in pharmaceutical formulations and in urine samples. Average recoveries of 100.8±1.7% was obtained in tablet, whereas a recovery of 97.5±2.0% was obtained for the total PX (PX+hydoxy-PX) in urine sample

  2. A competitive chemiluminescence enzyme immunoassay for rapid and sensitive determination of enrofloxacin

    Science.gov (United States)

    Yu, Fei; Wu, Yongjun; Yu, Songcheng; Zhang, Huili; Zhang, Hongquan; Qu, Lingbo; Harrington, Peter de B.

    With alkaline phosphatase (ALP)-adamantane (AMPPD) system as the chemiluminescence (CL) detection system, a highly sensitive, specific and simple competitive chemiluminescence enzyme immunoassay (CLEIA) was developed for the measurement of enrofloxacin (ENR). The physicochemical parameters, such as the chemiluminescent assay mediums, the dilution buffer of ENR-McAb, the volume of dilution buffer, the monoclonal antibody concentration, the incubation time, and other relevant variables of the immunoassay have been optimized. Under the optimal conditions, the detection linear range of 350-1000 pg/mL and the detection limit of 0.24 ng/mL were provided by the proposed method. The relative standard deviations were less than 15% for both intra and inter-assay precision. This method has been successfully applied to determine ENR in spiked samples with the recovery of 103%-96%. It showed that CLEIA was a good potential method in the analysis of residues of veterinary drugs after treatment of related diseases.

  3. Sensitive determination of phenolic acids in extra-virgin olive oil by capillary zone electrophoresis.

    Science.gov (United States)

    Carrasco Pancorbo, Alegría; Cruces-Blanco, Carmen; Segura Carretero, Antonio; Fernández Gutiérrez, Alberto

    2004-11-03

    A sensitive, rapid, efficient, and reliable method for the separation and determination of phenolic acids by capillary zone electrophoresis has been carried out. A detailed method optimization was carried out to separate 14 different compounds by studying parameters such as pH, type and concentration of buffer, applied voltage, and injection time. The separation was performed within 16 min, using a 25 mM sodium borate buffer (pH 9.6) at 25 kV with 8 s of hydrodynamic injection. With this method and using a liquid-liquid extraction system, with recovery values around 95%, it has been possible to detect small quantities of phenolic acids in olive oil samples. This is apparently the first paper showing the quantification of this specific family of phenolic compounds in virgin olive oil samples.

  4. Fast and Sensitive Method for Determination of Domoic Acid in Mussel Tissue

    Directory of Open Access Journals (Sweden)

    Elena Barbaro

    2016-01-01

    Full Text Available Domoic acid (DA, a neurotoxic amino acid produced by diatoms, is the main cause of amnesic shellfish poisoning (ASP. In this work, we propose a very simple and fast analytical method to determine DA in mussel tissue. The method consists of two consecutive extractions and requires no purification steps, due to a reduction of the extraction of the interfering species and the application of very sensitive and selective HILIC-MS/MS method. The procedural method was validated through the estimation of trueness, extract yield, precision, detection, and quantification limits of analytical method. The sample preparation was also evaluated through qualitative and quantitative evaluations of the matrix effect. These evaluations were conducted both on the DA-free matrix spiked with known DA concentration and on the reference certified material (RCM. We developed a very selective LC-MS/MS method with a very low value of method detection limit (9 ng g−1 without cleanup steps.

  5. The influences of sensitivity of ligand in determination of fluors with LaF3

    International Nuclear Information System (INIS)

    Muzakky; Lahagu, F.; Djawahiri, H.M.; Susiaturi, E.

    1996-01-01

    The influences of acetate and carbonate ligand as a binder of uranium in uranium-tetra fluoride solution, with 0,1 M HNO 3 acid condition was been studied. The aim of binding is to looses of uranium from UO 2 (F 4 ) 2- compound, so the free of fluoride were able detected with LaF 3 membrane electrode on potentiometric method. Base on the free of Fluoride, acetate ligand was more sensitive than carbonate ligand. The addition method was able to prevented influent of HF species in high acidity was realized. The method was use to determination of Fluoride in C oncentrated Uranium , and yield are 1,215x10 -5 M±1,957x10 -4 in acetate ligand and 3,957x10 -5 M±2,57x10 -4 in carbonate ligand. (author)

  6. Inverse shear viscosity (fluidity) scaled with melting point properties: Almost 'universal' behaviour of heavier alkalis

    International Nuclear Information System (INIS)

    Tankeshwar, K.; March, N.H.

    1997-07-01

    Some numerical considerations relating to the potential of mean force at the melting point of Rb metal are first presented, which argue against the existence of a well defined activation energy for the shear viscosity of this liquid. Therefore, a scaling approach is developed, based on a well established formula for the viscosity η m of sp liquid metals at their melting points T m . This approach is shown to lead to an 'almost' universal plot of scaled fluidity η -1 η m against (T/T m ) 1/2 for the liquid alkali metals, excluding Li. This metal is anomalous because it is a strong scattering liquid, in marked contrast to the other alkali metals. (author). 9 refs, 3 figs, 1 tab

  7. Sensitive determination of total particulate phosphorus and particulate inorganic phosphorus in seawater using liquid waveguide spectrophotometry.

    Science.gov (United States)

    Ehama, Makoto; Hashihama, Fuminori; Kinouchi, Shinko; Kanda, Jota; Saito, Hiroaki

    2016-06-01

    Determining the total particulate phosphorus (TPP) and particulate inorganic phosphorus (PIP) in oligotrophic oceanic water generally requires the filtration of a large amount of water sample. This paper describes methods that require small filtration volumes for determining the TPP and PIP concentrations. The methods were devised by validating or improving conventional sample processing and by applying highly sensitive liquid waveguide spectrophotometry to the measurements of oxidized or acid-extracted phosphate from TPP and PIP, respectively. The oxidation of TPP was performed by a chemical wet oxidation method using 3% potassium persulfate. The acid extraction of PIP was initially carried out based on the conventional extraction methodology, which requires 1M HCl, followed by the procedure for decreasing acidity. While the conventional procedure for acid removal requires a ten-fold dilution of the 1M HCl extract with purified water, the improved procedure proposed in this study uses 8M NaOH solution for neutralizing 1M HCl extract in order to reduce the dilution effect. An experiment for comparing the absorbances of the phosphate standard dissolved in 0.1M HCl and of that dissolved in a neutralized solution [1M HCl: 8M NaOH=8:1 (v:v)] exhibited a higher absorbance in the neutralized solution. This indicated that the improved procedure completely removed the acid effect, which reduces the sensitivity of the phosphate measurement. Application to an ultraoligotrophic water sample showed that the TPP concentration in a 1075mL-filtered sample was 8.4nM with a coefficient of variation (CV) of 4.3% and the PIP concentration in a 2300mL-filtered sample was 1.3nM with a CV of 6.1%. Based on the detection limit (3nM) of the sensitive phosphate measurement and the ambient TPP and PIP concentrations of the ultraoligotrophic water, the minimum filtration volumes required for the detection of TPP and PIP were estimated to be 15 and 52mL, respectively. Copyright © 2016

  8. Membrane Fluidity Changes, A Basic Mechanism of Interaction of Gravity with Cells?

    Science.gov (United States)

    Kohn, Florian; Hauslage, Jens; Hanke, Wolfgang

    2017-10-01

    All life on earth has been established under conditions of stable gravity of 1g. Nevertheless, in numerous experiments the direct gravity dependence of biological processes has been shown on all levels of organization, from single molecules to humans. According to the underlying mechanisms a variety of questions, especially about gravity sensation of single cells without specialized organelles or structures for gravity sensing is being still open. Biological cell membranes are complex structures containing mainly lipids and proteins. Functional aspects of such membranes are usually attributed to membrane integral proteins. This is also correct for the gravity dependence of cells and organisms which is well accepted since long for a wide range of biological systems. However, it is as well established that parameters of the lipid matrix are directly modifying the function of proteins. Thus, the question must be asked, whether, and how far plain lipid membranes are affected by gravity directly. In principle it can be said that up to recently no real basic mechanism for gravity perception in single cells has been presented or verified. However, it now has been shown that as a basic membrane parameter, membrane fluidity, is significantly dependent on gravity. This finding might deliver a real basic mechanism for gravity perception of living organisms on all scales. In this review we summarize older and more recent results to demonstrate that the finding of membrane fluidity being gravity dependent is consistent with a variety of published laboratory experiments. We additionally point out to the consequences of these recent results for research in the field life science under space condition.

  9. Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

    Energy Technology Data Exchange (ETDEWEB)

    Thapliyal, Neeta Bachheti, E-mail: thapliyaln@ukzn.ac.za; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar, E-mail: karpoormath@ukzn.ac.za; Cherukupalli, Srinivasulu

    2017-05-01

    A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

  10. Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

    International Nuclear Information System (INIS)

    Thapliyal, Neeta Bachheti; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar; Cherukupalli, Srinivasulu

    2017-01-01

    A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

  11. Sensitivity Analysis of Electromagnetic Induction Technique to Determine Soil Salinity in Large –Scale

    Directory of Open Access Journals (Sweden)

    Yousef Hasheminejhad

    2017-02-01

    Full Text Available Introduction: Monitoring and management of saline soils depends on exact and updatable measurements of soil electrical conductivity. Large scale direct measurements are not only expensive but also time consuming. Therefore application of near ground surface sensors could be considered as acceptable time- and cost-saving methods with high accuracy in soil salinity detection. . One of these relatively innovative methods is electromagnetic induction technique. Apparent soil electrical conductivity measurement by electromagnetic induction technique is affected by several key properties of soils including soil moisture and clay content. Materials and Methods: Soil salinity and apparent soil electrical conductivity data of two years of 50000 ha area in Sabzevar- Davarzan plain were used to evaluate the sensitivity of electromagnetic induction to soil moisture and clay content. Locations of the sampling points were determined by the Latin Hypercube Sampling strategy, based on 100 sampling points were selected for the first year and 25 sampling points for the second year. Regarding to difficulties in finding and sampling the points 97 sampling points were found in the area for the first year out of which 82 points were sampled down to 90 cm depth in 30 cm intervals and all of them were measured with electromagnetic induction device at horizontal orientation. The first year data were used for training the model which included 82 points measurement of bulk conductivity and laboratory determination of electrical conductivity of saturated extract, soil texture and moisture content in soil samples. On the other hand, the second year data which were used for testing the model integrated by 25 sampling points and 9 bulk conductivity measurements around each point. Electrical conductivity of saturated extract was just measured as the only parameter in the laboratory for the second year samples. Results and Discussion: Results of the first year showed a

  12. Determination of the soil hazardous concentrations of bisphenol A using the species sensitivity approach.

    Science.gov (United States)

    Kwak, Jin Il; Moon, Jongmin; Kim, Dokyung; Cui, Rongxue; An, Youn-Joo

    2018-02-15

    This study describes the determination of the species sensitivity distribution (SSD)-based soil hazardous contamination of bisphenol A for environmental risk assessment. We conducted a battery of bioassays, including acute assays using eight species from six different taxonomic groups and chronic assays using five species from four different taxonomic groups. We determined that our dataset satisfied Australia & New Zealand's guidelines for applying the SSD methodology. Finally, the chronic soil HC 5 and HC 50 values for bisphenol A were estimated to be 13.7 and 74.7mg/kg soil, respectively, for soil ecosystem protection against chronic exposure using the data generated from this and previous studies. Because the soil standard values of bisphenol A for protection of the soil ecosystem are not currently available, the HC values of bisphenol A that we suggested based on the SSD approach would be applied as fundamental data to establish soil standards of bisphenol A for soil ecosystem protection. To our knowledge, this is the first study reporting the soil hazardous concentration of bisphenol A for environmental risk assessment. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Highly sensitive determination of poly(hexamethylene guanidine) by Rayleigh scattering using aggregation of silver nanoparticles

    International Nuclear Information System (INIS)

    Artemyeva, Anastasia A.; Sharov, Andrei V.; Beklemishev, Mikhail K.; Samarina, Tatyana O.; Abramchuk, Sergei S.; Ovcharenko, Elena O.; Dityuk, Alexander I.; Efimov, Konstantin M.

    2015-01-01

    We have found that low concentrations of the polycationic disinfectant poly(hexamethylene guanidine) hydrochloride (PHMG) induce the aggregation of citrate-stabilized silver nanoparticles (AgNPs) in aqueous solution. Based on this finding, we have worked out a method to the determination of PHMG. The protocol includes the steps of (a) centrifuging the water sample, (b) addition of an aliquot of the colloidal solution of the AgNPs, and (c) measurement of the intensity of scattered light. The method is surprisingly selective in that comparable concentrations of surfactants, humic acids and protein do not interfere. Besides, an up to 50 mM concentration NaCl, and up to 5 mM of Mg(II) or Ca(II) are tolerated. Other cationic polyelectrolytes, polyethyleneimine and poly(dimethyldiallyammonium chloride), also cause aggregation of AgNPs but to a lesser extent. The determination of PHMG was performed in spiked samples (run-off, tap and swimming pool waters) with detection limits of 2·10 −8 , 4·10 −7 , and 6·10 −6 M (by monomer unit), respectively. The linear ranges are wider and the detection limits are lower than those of known spectrophotometric methods. It is necessary, however, to correct the calibration plot for background scattering by the sample and to establish a calibration plot for each kind of water sample. Notwithstanding this, the approach is attractive because it is sensitive, rapid, and simple. (author)

  14. Sensitive determination of mercury by a miniaturized spectrophotometer after in situ single-drop microextraction.

    Science.gov (United States)

    Yang, Fangwen; Liu, Rui; Tan, Zhiqiang; Wen, Xiaodong; Zheng, Chengbin; Lv, Yi

    2010-11-15

    An in situ single-drop microextraction (SDME) method was developed for trace mercury determination by a miniaturized spectrophotometer, in which a simple and cheap light-emitting diode (LED) was employed as the light source, and a handheld charge coupled device (CCD) was served as the detector. A droplet of 0.006% dithizone-CCl(4) (m/v) was used as extraction phase and hanged on a rolled PTFE tube. LED light was adjusted carefully to pass through the centre of the droplet and the entrance slit of the CCD detector. The radiation intensities of 475 nm before and after SDME (I(0) and I(i)) were recorded for quantification. Under the optimum conditions, the system provided a linear range of 2-50 μg L(-1), with a correlation coefficient of 0.9983 and a limit of detection (3σ) of 0.2 μg L(-1). The enrichment factor was about 69. The present method showed the merits of high sensitivity, simplicity, rapidity, low reagent consumption and field analysis potential. Finally, this method was successfully applied for the determination of the total mercury in spiked tap water sample, spiked river water sample and certified reference material (GBW (E) 080393, simulated water). Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Sensitive determination of mercury by a miniaturized spectrophotometer after in situ single-drop microextraction

    International Nuclear Information System (INIS)

    Yang Fangwen; Liu Rui; Tan Zhiqiang; Wen Xiaodong; Zheng Chengbin; Lv Yi

    2010-01-01

    An in situ single-drop microextraction (SDME) method was developed for trace mercury determination by a miniaturized spectrophotometer, in which a simple and cheap light-emitting diode (LED) was employed as the light source, and a handheld charge coupled device (CCD) was served as the detector. A droplet of 0.006% dithizone-CCl 4 (m/v) was used as extraction phase and hanged on a rolled PTFE tube. LED light was adjusted carefully to pass through the centre of the droplet and the entrance slit of the CCD detector. The radiation intensities of 475 nm before and after SDME (I 0 and I i ) were recorded for quantification. Under the optimum conditions, the system provided a linear range of 2-50 μg L -1 , with a correlation coefficient of 0.9983 and a limit of detection (3σ) of 0.2 μg L -1 . The enrichment factor was about 69. The present method showed the merits of high sensitivity, simplicity, rapidity, low reagent consumption and field analysis potential. Finally, this method was successfully applied for the determination of the total mercury in spiked tap water sample, spiked river water sample and certified reference material (GBW (E) 080393, simulated water).

  16. A highly sensitive kinetic spectrophotometric method for the determination of ascorbic Acid in pharmaceutical samples.

    Science.gov (United States)

    Shishehbore, Masoud Reza; Aghamiri, Zahra

    2014-01-01

    In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 - 33.5 μg mL(-1) of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 μg mL(-1) of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 μg mL(-) (1) of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method.

  17. Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers

    DEFF Research Database (Denmark)

    Colombi, Paolo; Bergese, Paolo; Bontempi, Elza

    2013-01-01

    A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C......) with subnanometer thickness resolution on SU-8 MC arrays by means of atomic layer deposition. The resonant frequencies of the MCs were measured before and after coating and the elastic moduli of the films were determined by a theoretical model developed for this purpose. The Young's modulus of thicker TiO2 films...... (>75 nm) was estimated to be about 110 GPa, this value being consistent with the value of amorphous TiO2. On the other hand we observed a marked decrease of the Young's modulus for TiO2 films with a thickness below 50 nm. This behavior was found not to be related to a decrease of the film mass density...

  18. Sensitive and selective spectrophotometric determination of pantoprazole sodium in pharmaceuticals using permanganate

    Directory of Open Access Journals (Sweden)

    K. B. VINAY

    2010-03-01

    Full Text Available A simple visible spectrophotometric method is described for the determination of pantoprazole sodium sesquihydrate (PSS. The method is based on the formation of a brown colored product on treating PSS with permanganate in neutral medium, the absorbance being measured at 350 nm. The experimental conditions for the assay were optimized. The absorbance is found to increase linearly with the concentration of PSS and the calibration graph is linear in the range of 2.5-40.0 μg ml-1 with a linear regression coefficient of 0.998. The calculated molar absorptivity value is 1.27x104 l mol-1 cm-1 and the corresponding Sandel sensitivity is 0.0341 µg cm-2. The limits of detection (LOD and quantification (LOQ are calculated to be 0.49 and 1.47 µg ml-1, respectively. Intra-day and inter-day accuracy expressed as relative error were better than 2.0% and the corresponding precision (RSD was less than 2.5 %. The developed and validated method was applied to the determination of the active ingredient in a tablet dosage form and the results obtained agreed well with those of the reference method. The accuracy and reliability of the method were ascertained by performing recovery experiments via standard-addition procedure.

  19. Highly Selective and Sensitized Spectrophotometric Determination of Iron (3) Following Potentiometric Study

    International Nuclear Information System (INIS)

    Shokrollahi, A.; Ghaedi, M.; Rajabi, H.R.

    2007-01-01

    A simple, selective and sensitized spectrophotometric method for determination of trace amounts of Fe 3+ ion in tap and waste water solutions has been described. The spectrophotometric determination of Fe 3+ ion using Ferron in the presence of N,N-Dodecy trimethylammonium bromide (DTAB) has been carried out. The Beer's law is obeyed over the concentration range of 0.05-2.6 μg mL -1 of Fe 3+ ion with the relative standard deviation (RSD %) 3 L mol -1 cm -1 . Potentiometric pH titration has been used for prediction of protonation constants of ferron, and evaluating its stoichiometry and respective stability constant with Fe 3+ ion. As it is obvious the most likely species of ferron alone and its complexes are LH (log=7.64), LH 2 (logK=10.52), LH 3 (logK=11.74) and ML 2 (logβ= 23.68), ML 3 (logβ23.68), ML 3 H (logβ= 23.68), ML 3 H 2 (logβ= 23.68) and ML(OH) 2 (logβ=23.68) respectively

  20. Sensitive Electrochemical Determination of Gallic Acid: Application in Estimation of Total Polyphenols in Plant Samples

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Sheikh-Mohseni

    2016-12-01

    Full Text Available A modified electrode was prepared by modification of the carbon paste electrode (CPE with graphene nano-sheets. The fabricated modified electrode exhibited an electrocatalytic activity toward gallic acid (GA oxidation because of good conductivity, low electron transfer resistance and catalytic effect. The graphene modified CPE had a lower overvoltage and enhanced electrical current respect to the bare CPE for the oxidation of GA. The oxidation potential of GA decreased more than 210 mV by the modified electrode. The modified electrode responded to the GA in the concentration range of 3.0 × 10-5-1.5 × 10-4 M with high sensitivity by the technique of differential pulse voltammetry. Also, detection limit of 1.1 × 10-7 M was obtained by this modified electrode for GA. This electrode was used for the successful determination of GA in plant samples. Therefore, the content of total polyphenols in plant samples can be determined by the proposed modified electrode based on the concentration of GA in the sample.

  1. A rapid and sensitive alcohol oxidase/catalase conductometric biosensor for alcohol determination.

    Science.gov (United States)

    Hnaien, M; Lagarde, F; Jaffrezic-Renault, N

    2010-04-15

    A new conductometric biosensor has been developed for the determination of short chain primary aliphatic alcohols. The biosensor assembly was prepared through immobilization of alcohol oxidase from Hansenula sp. and bovine liver catalase in a photoreticulated poly(vinyl alcohol) membrane at the surface of interdigitated microelectrodes. The local conductivity increased rapidly after alcohol addition, reaching steady-state within 10 min. The sensitivity was maximal for methanol (0.394+/-0.004 microS microM(-1), n=5) and decreased by increasing the alcohol chain length. The response was linear up to 75 microM for methanol, 70 microM for ethanol and 65 microM for 1-propanol and limits of detection were 0.5 microM, 1 microM and 3 microM, respectively (S/N=3). No significant loss of the enzyme activities was observed after 3 months of storage at 4 degrees C in a 20mM phosphate buffer solution pH 7.2 (two or three measurements per week). After 4 months, 95% of the initial signal still remained. The biosensor response to ethanol was not significantly affected by acetic, lactic, ascorbic, malic, oxalic, citric, tartaric acids or glucose. The bi-enzymatic sensor was successfully applied to the determination of ethanol in different alcoholic beverages. (c) 2009 Elsevier B.V. All rights reserved.

  2. A novel bi-enzyme electrochemical biosensor for selective and sensitive determination of methyl salicylate.

    Science.gov (United States)

    Fang, Yi; Umasankar, Yogeswaran; Ramasamy, Ramaraja P

    2016-07-15

    An amperometric sensor based on a bi-enzyme modified electrode was fabricated to detect methyl salicylate, a volatile organic compound released by pathogen-infected plants via systemic response. The detection is based on cascadic conversion reactions that result in an amperometric electrochemical signal. The bi-enzyme electrode is made of alcohol oxidase and horseradish peroxidase enzymes immobilized on to a carbon nanotube matrix through a molecular tethering method. Methyl salicylate undergoes hydrolysis to form methanol, which is consumed by alcohol oxidase to form formaldehyde while simultaneously reducing oxygen to hydrogen peroxide. The hydrogen peroxide will be further reduced to water by horseradish peroxidase, which results in an amperometric signal via direct electron transfer. The bi-enzyme biosensor was evaluated by cyclic voltammetry and constant potential amperometry using hydrolyzed methyl salicylate as the analyte. The sensitivity of the bi-enzyme biosensor as determined by cyclic voltammetry and constant potential amperometry were 112.37 and 282.82μAcm(-2)mM(-1) respectively, and the corresponding limits of detection were 22.95 and 0.98μM respectively. Constant potential amperometry was also used to evaluate durability, repeatability and interference from other compounds. Wintergreen oil was used for real sample study to establish the application of the bi-enzyme sensor for selective determination of plant pathogen infections. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Sex-specific genetic determinants for arterial stiffness in Dahl salt-sensitive hypertensive rats.

    Science.gov (United States)

    Decano, Julius L; Pasion, Khristine A; Black, Nicole; Giordano, Nicholas J; Herrera, Victoria L; Ruiz-Opazo, Nelson

    2016-01-11

    Arterial stiffness is an independent predictor of cardiovascular outcomes in hypertensive patients including myocardial infarction, fatal stroke, cerebral micro-bleeds which predicts cerebral hemorrhage in hypertensive patients, as well as progression to hypertension in non-hypertensive subjects. The association between arterial stiffness and various cardiovascular outcomes (coronary heart disease, stroke) remains after adjusting for age, sex, blood pressure, body mass index and other known predictors of cardiovascular disease, suggesting that arterial stiffness, measured via carotid-femoral pulse wave velocity, has a better predictive value than each of these factors. Recent evidence shows that arterial stiffening precedes the onset of high blood pressure; however their molecular genetic relationship (s) and sex-specific determinants remain uncertain. We investigated whether distinct or shared genetic determinants might underlie susceptibility to arterial stiffening in male and female Dahl salt-sensitive rats. Thus, we performed a genome-wide scan for quantitative trait loci (QTLs) affecting arterial stiffness in six-week old F2 (Dahl S x R)-intercross male and female rats characterized for abdominal aortic pulse wave velocity and aortic strain by high-resolution ultrasonography. We detected five highly significant QTLs affecting aortic stiffness: two interacting QTLs (AS-m1 on chromosome 4 and AS-m2 on chromosome16, LOD 8.8) in males and two distinct interacting QTLs (AS-f1 on chromosome 9 and AS-f2 on chromosome11, LOD 8.9) in females affecting pulse wave velocity. One QTL (AS-1 on chromosome 3, LOD 4.3) was found to influence aortic strain in a sex-independent manner. None of these arterial stiffness QTLs co-localized with previously reported blood pressure QTLs detected in equivalent genetic intercrosses. These data reveal sex-specific genetic determinants for aortic pulse wave velocity and suggest distinct polygenic susceptibility for arterial stiffness and

  4. Sensitive cell-based assay for determination of human immunodeficiency virus type 1 coreceptor tropism.

    Science.gov (United States)

    Weber, Jan; Vazquez, Ana C; Winner, Dane; Gibson, Richard M; Rhea, Ariel M; Rose, Justine D; Wylie, Doug; Henry, Kenneth; Wright, Alison; King, Kevin; Archer, John; Poveda, Eva; Soriano, Vicente; Robertson, David L; Olivo, Paul D; Arts, Eric J; Quiñones-Mateu, Miguel E

    2013-05-01

    CCR5 antagonists are a powerful new class of antiretroviral drugs that require a companion assay to evaluate the presence of CXCR4-tropic (non-R5) viruses prior to use in human immunodeficiency virus (HIV)-infected individuals. In this study, we have developed, characterized, verified, and prevalidated a novel phenotypic test to determine HIV-1 coreceptor tropism (VERITROP) based on a sensitive cell-to-cell fusion assay. A proprietary vector was constructed containing a near-full-length HIV-1 genome with the yeast uracil biosynthesis (URA3) gene replacing the HIV-1 env coding sequence. Patient-derived HIV-1 PCR products were introduced by homologous recombination using an innovative yeast-based cloning strategy. The env-expressing vectors were then used in a cell-to-cell fusion assay to determine the presence of R5 and/or non-R5 HIV-1 variants within the viral population. Results were compared with (i) the original version of Trofile (Monogram Biosciences, San Francisco, CA), (ii) population sequencing, and (iii) 454 pyrosequencing, with the genotypic data analyzed using several bioinformatics tools, i.e., the 11/24/25 rule, Geno2Pheno (2% to 5.75%, 3.5%, or 10% false-positive rate [FPR]), and webPSSM. VERITROP consistently detected minority non-R5 variants from clinical specimens, with an analytical sensitivity of 0.3%, with viral loads of ≥1,000 copies/ml, and from B and non-B subtypes. In a pilot study, a 73.7% (56/76) concordance was observed with the original Trofile assay, with 19 of the 20 discordant results corresponding to non-R5 variants detected using VERITROP and not by the original Trofile assay. The degree of concordance of VERITROP and Trofile with population and deep sequencing results depended on the algorithm used to determine HIV-1 coreceptor tropism. Overall, VERITROP showed better concordance with deep sequencing/Geno2Pheno at a 0.3% detection threshold (67%), whereas Trofile matched better with population sequencing (79%). However, 454

  5. Determine spray droplets on water sensitive paper (WSP) for low pressure deflector nozzle using image J

    Science.gov (United States)

    Sies, M. F.; Madzlan, N. F.; Asmuin, N.; Sadikin, A.; Zakaria, H.

    2017-09-01

    In this study, determine of spray droplets size (SMD) using water sensitive paper (WSP) at low fluid pressure with deflector nozzle or tangential flow nozzle model Delavan AL75 and New Design Nozzle with two different type of swirl (ND2.5 A1.0 & ND2.5 B1.0). These three deflected flat sprays have used at different liquid mixing ratio. These liquid mixture ratios are pure water, 10% of lime juice + 90% of water (L10W90) and 30% of lime juice + 70% of water (L30W70). WSP is used to collect the spray droplets from nozzles. The operational liquid pressure of each nozzle is 3 bar, while air operational pressures are 3 bar and 6 bar. Then, the WSP were scanned using scanner then it was analyzed using ImageJ software. ImageJ can be used for determining the diameter of droplets size on the WSP. As the results from an experiment, the AL75 nozzle recorded the lowest Sauter mean diameter which is 193.69μm at 6 bar of pressurized air while ND2.5 A1.0 recorded the highest Sauter mean diameter which is 353.61µm at 3 bar of pressurized air. Summary from the experiment shows that the higher of droplet size is because of the lower air pressure (3 Bar). Then, increasing of liquid viscosity also increase the SMD. The orifice diameter for New Design nozzle (ND-2.5) is smaller than AL75, which are 2.5mm and 2.8mm respectively. The different nozzle design also gives effect the SMD. WSP is an alternative method to determine SMD for spray droplets with the low cost if compared to Phase Doppler Anemometry (PDA).

  6. Diagnostic sensitivity of ultrasound, radiography and computed tomography for gender determination in four species of lizards.

    Science.gov (United States)

    Di Ianni, Francesco; Volta, Antonella; Pelizzone, Igor; Manfredi, Sabrina; Gnudi, Giacomo; Parmigiani, Enrico

    2015-01-01

    Gender determination is frequently requested by reptile breeders, especially for species with poor or absent sexual dimorphism. The aims of the current study were to describe techniques and diagnostic sensitivities of ultrasound, radiography, and computed tomography for gender determination (identification of hemipenes) in four species of lizards. Nineteen lizards of known sex, belonging to four different species (Pogona vitticeps, Uromastyx aegyptia, Tiliqua scincoides, Gerrhosaurus major) were prospectively enrolled. With informed owner consent, ultrasound, noncontrast CT, contrast radiography, and contrast CT (with contrast medium administered into the cloaca) were performed in conscious animals. Imaging studies were reviewed by three different operators, each unaware of the gender of the animals and of the results of the other techniques. The lizard was classified as a male when hemipenes were identified. Nineteen lizards were included in the study, 10 females and nine males. The hemipenes were seen on ultrasound in only two male lizards, and appeared as oval hypoechoic structures. Radiographically, hemipenes filled with contrast medium appeared as spindle-shaped opacities. Noncontrast CT identified hemipenes in only two lizards, and these appeared as spindle-shaped kinked structures with hyperattenuating content consistent with smegma. Hemipenes were correctly identified in all nine males using contrast CT (accuracy of 100%). Accuracy of contrast radiography was excellent (94.7%). Accuracy of ultrasound and of noncontrast CT was poor (64.3% and 63.1%, respectively). Findings from the current study supported the use of contrast CT or contrast radiography for gender determination in lizards. © 2014 American College of Veterinary Radiology.

  7. Sensitive determination of bisphenol A base on arginine functionalized nanocomposite graphene film

    International Nuclear Information System (INIS)

    Zhang Yan; Wang Letao; Lu Daban; Shi Xuezhao; Wang Chunming; Duan Xiaojuan

    2012-01-01

    Highlights: ► The water-soluble arginine functionalized graphene was produced successfully by an environment-friendly method. ► Electrochemical behaviors and some kinetic parameters of bisphenol A on the Arg-G/GCE were investigated. ► The proposed sensor showed more outstanding sensitivity properties toward the bisphenol A than the reported sensors. ► The proposed method opened a new simply way to detection of bisphenol A in the environmental protection. - Abstract: Arginine (Arg) functionalized graphene (Arg-G) nanocomposite was produced successfully by an environment-friendly method, and the morphology of the nanocomposite was characterized by transmission electron microscopy (TEM), Raman spectra, etc. Based on Arg-G nanocomposite, an electrochemical sensor was fabricated for sensitive detection of bisphenol A (BPA). The electrochemical behaviors of BPA on Arg-G modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Experimental parameters, such as the accumulation potential and time, scan rate, and the pH value of buffer solution were optimized. Under the optimized conditions, the oxidation peak current was proportional to BPA concentration in the range between 5.0 nmol/L and 40.0 μmol/L with the correlation coefficient of 0.9986 and the limit of detection of 1.1 nmol/L (S/N = 3). Moreover, the fabricated electrode also exhibited good reproducibility and stability. The proposed sensor was successfully employed to determine BPA in real plastic products and the recoveries were satisfactory.

  8. Genetic Determinism of Sensitivity to Corynespora cassiicola Exudates in Rubber Tree (Hevea brasiliensis).

    Science.gov (United States)

    Tran, Dinh Minh; Clément-Demange, André; Déon, Marine; Garcia, Dominique; Le Guen, Vincent; Clément-Vidal, Anne; Soumahoro, Mouman; Masson, Aurélien; Label, Philippe; Le, Mau Tuy; Pujade-Renaud, Valérie

    2016-01-01

    An indirect phenotyping method was developed in order to estimate the susceptibility of rubber tree clonal varieties to Corynespora Leaf Fall (CLF) disease caused by the ascomycete Corynespora cassiicola. This method consists in quantifying the impact of fungal exudates on detached leaves by measuring the induced electrolyte leakage (EL%). The tested exudates were either crude culture filtrates from diverse C. cassiicola isolates or the purified cassiicolin (Cas1), a small secreted effector protein produced by the aggressive isolate CCP. The test was found to be quantitative, with the EL% response proportional to toxin concentration. For eight clones tested with two aggressive isolates, the EL% response to the filtrates positively correlated to the response induced by conidial inoculation. The toxicity test applied to 18 clones using 13 toxinic treatments evidenced an important variability among clones and treatments, with a significant additional clone x treatment interaction effect. A genetic linkage map was built using 306 microsatellite markers, from the F1 population of the PB260 x RRIM600 family. Phenotyping of the population for sensitivity to the purified Cas1 effector and to culture filtrates from seven C. cassiicola isolates revealed a polygenic determinism, with six QTL detected on five chromosomes and percentages of explained phenotypic variance varying from 11 to 17%. Two common QTL were identified for the CCP filtrate and the purified cassiicolin, suggesting that Cas1 may be the main effector of CCP filtrate toxicity. The CCP filtrate clearly contrasted with all other filtrates. The toxicity test based on Electrolyte Leakage Measurement offers the opportunity to assess the sensitivity of rubber genotypes to C. cassiicola exudates or purified effectors for genetic investigations and early selection, without risk of spreading the fungus in plantations. However, the power of this test for predicting field susceptibility of rubber clones to CLF will have

  9. Simple Sensitive Spectrophotometric Determination of Vanadium in Biological and Environmental Samples

    Directory of Open Access Journals (Sweden)

    B. Krishna Priya

    2006-01-01

    Full Text Available Novel, rapid, highly sensitive and selective spectrophotometric method for the determination of traces of vanadium (V in environmental and biological samples, pharmaceutical and steel samples was studied. The method is based on oxidation of 2,4- dinitro phenyl hydrazine(2,4-DNPH by vanadium (V followed by coupling reaction with N-(1-naphthalene-1-ylethane-1,2-diamine-dihydrochloride (NEDA in acidic medium to give red colored derivative or on oxidation of 4-Amino Pyridine by vanadium (V followed by coupling reaction with NEDA in basic medium to give pink colored derivative. The red colored derivative having an λmax 495 nm which is stable for 8 days and the pink colored derivative with 525 nm is stable for more than 7 days at 350C. Beer's law is obeyed for vanadium (V in the concentration range of 0.02 - 3.5 μg mL–1 (red derivative and 0.03 – 4.5 μg mL–1 (pink derivative at the wave length of maximum absorption. The optimum reaction conditions and other analytical parameters were investigated to enhance the sensitivity of the present method. The detailed study of various interferences made the method more selective. The proposed method was successfully applied to the analysis of vanadium in natural water samples, plant material, soil samples, synthetic mixtures, pharmaceutical samples and biological samples. The results obtained were agreed with the reported methods at the 95 % confidence level. The performance of proposed method was evaluated in terms of Student's t-test and Variance ratio f-test which indicates the significance of proposed method over reported method.

  10. Coal lithotypes before and after saturation with CO{sub 2}; insights from micro- and mesoporosity, fluidity, and functional group distribution

    Energy Technology Data Exchange (ETDEWEB)

    Mastalerz, M.; Drobniak, A. [Indiana Geological Survey, Indiana University, 611 North Walnut Grove Ave., Bloomington, IN 47405-2208 (United States); Walker, R. [Pearson Coal Petrography, 7300 W. 15th Ave, Gary, IN 46406 (United States); Morse, D. [Illinois State Geological Survey, University of Illinois, Champaign, Illinois, 61820 (United States)

    2010-09-01

    Four lithotypes, vitrain, bright clarain, clarain, and fusain, were hand-picked from the core of the Pennsylvanian Springfield Coal Member (Petersburg Formation) in Illinois. These lithotypes were analyzed petrographically and for meso- and micropore characteristics, functional group distribution using FTIR techniques, and fluidity. High-pressure CO{sub 2} adsorption isotherm analyses of these lithotypes were performed and, subsequently, all samples were reanalyzed in order to investigate the effects of CO{sub 2}. After the high-pressure adsorption isotherm analysis was conducted and the samples were reanalyzed, there was a decrease in BET surface area for vitrain from 31.5 m{sup 2}/g in the original sample to 28.5 m{sup 2}/g, as determined by low-pressure nitrogen adsorption. Bright clarain and clarain recorded a minimal decrease in BET surface area, whereas for fusain there was an increase from 6.6 m{sup 2}/g to 7.9 m{sup 2}/g. Using low-pressure CO{sub 2} adsorption techniques, a small decrease in the quantity of the adsorbed CO{sub 2} is recorded for vitrain and bright clarain, no difference is observed for clarain, and there is an increase in the quantity of the adsorbed CO{sub 2} for fusain. Comparison of the FTIR spectra before and after CO{sub 2} injection for all lithotypes showed no differences with respect to functional group distribution, testifying against chemical nature of CO{sub 2} adsorption. Gieseler plastometry shows that: 1) softening temperature is higher for the post-CO{sub 2} sample (389.5 C vs. 386 C); 2) solidification temperature is lower for the post-CO{sub 2} sample (443.5 C vs. 451 C); and 3) the maximum fluidity is significantly lower for the post-CO{sub 2} sample (4 ddpm vs. 14 ddpm). (author)

  11. Factors determining sensitivity or resistance of tumor cell lines towards artesunate.

    Science.gov (United States)

    Sertel, Serkan; Eichhorn, Tolga; Sieber, Sebastian; Sauer, Alexandra; Weiss, Johanna; Plinkert, Peter K; Efferth, Thomas

    2010-04-15

    Clinical oncology is still challenged by the development of drug resistance of tumors that result in poor prognosis for patients. There is an urgent necessity to understand the molecular mechanisms of resistance and to develop novel therapy strategies. Artesunate (ART) is an anti-malarial drug, which also exerts profound cytotoxic activity towards cancer cells. We first applied a gene-hunting approach using cluster and COMPARE analyses of microarray-based transcriptome-wide mRNA expression profiles. Among the genes identified by this approach were genes from diverse functional groups such as structural constituents of ribosomes (RPL6, RPL7, RPS12, RPS15A), kinases (CABC1, CCT2, RPL41), transcriptional and translational regulators (SFRS2, TUFM, ZBTB4), signal transducers (FLNA), control of cell growth and proliferation (RPS6), angiogenesis promoting factors (ITGB1), and others (SLC25A19, NCKAP1, BST1, DBH, FZD7, NACA, MTHFD2). Furthermore, we applied a candidate gene approach and tested the role of resistance mechanisms towards established anti-cancer drugs for ART resistance. By using transfected or knockout cell models we found that the tumor suppressor p16(INK4A) and the anti-oxidant protein, catalase, conferred resistance towards ART, while the oncogene HPV-E6 conferred sensitivity towards ART. The tumor suppressor p53 and its downstream protein, p21, as well as the anti-oxidant manganese-dependent superoxide dismutase did not affect cellular response to ART. In conclusion, our pharmacogenomic approach revealed that response of tumor cells towards ART is multi-factorial and is determined by gene expression associated with either ART sensitivity or resistance. At least some of the functional groups of genes (e.g. angiogenesis promoting factors, cell growth and proliferation-associated genes signal transducers and kinases) are also implicated in clinical responsiveness of tumors towards chemotherapy. It merits further investigation, whether ART is responsive in

  12. Sensitive spectrophotometric determination of metoclopramide hydrochloride in dosage forms and spiked human urine using vanillin

    Directory of Open Access Journals (Sweden)

    O. Zenita Devi

    2016-09-01

    Full Text Available A new spectrophotometric method which is simple, sensitive, selective and rapid is described for the determination of metoclopramide hydrochloride (MCP in bulk drug and in dosage forms using vanillin as the chromogenic agent. The method is based on the condensation reaction between primary aromatic amine group present in MCP with aromatic aldehyde, vanillin to produce an intense yellow colored product. The resulting Schiff’s base shows an absorption maximum at 410 nm and the reaction product is stable for more than one day. The reaction was carried out in acetic acid and perchloric acid medium. Beer’s law was obeyed in the concentration range 1.5–15.0 μg ml−1 MCP with a molar absorptivity of 1.89 × 104 l mol−1 cm−1. The limit of detection (LOD and limit of quantification (LOQ were found to be 0.51 and 1.55 μg ml−1, respectively. The method was statistically evaluated by calculating percent relative error (% RE for accuracy and percent relative standard deviation (% RSD for precision, and was applied successfully to the determination of MCP in tablets, in injection and also in spiked human urine. No interference was observed from common additives found in pharmaceutical preparations. The results obtained by the proposed method were validated statistically by comparing the results with those of the reference method by applying the Student’s t-test and F-test. The accuracy and reliability of the method were further ascertained by performing recovery tests via standard-addition technique.

  13. Sensitivity and Specificity of Procalcitonin to Determine Etiology of Diarrhea in Children Younger Than 5 Years

    Science.gov (United States)

    Ismaili-Jaha, Vlora; Shala, Mujë; Azemi, Mehmedali; Spahiu, Shqipe; Hoxha, Teuta; Avdiu, Muharrem; Spahiu, Lidvana

    2014-01-01

    Aim: The aim of this study is to assess the sensitivity and specificity of procalcitonin to determine bacterial etiology of diarrhea. The examinees and methods: For this purpose we conducted the study comprising 115 children aged 1 to 60 months admitted at the Department of Pediatric Gastroenterology, Pediatric Clinic, divided in three groups based on etiology of the diarrhea that has been confirmed with respective tests during the hospitalization. Each group has equal number of patients – 35. The first group was confirmed to have bacterial diarrhea, the second viral diarrhea and the third extra intestinal diarrhea. The determination of procalcitonin has been established with the ELFA methods of producer B.R.A.H.M.S Diagnostica GmbH, Berlin, (Germany). Results: From the total number of 1130 patient with acute diarrhea procalcitonin was assessed in 105. 67 (63.8%) of these patient were male. More than one third (38.14%) of the children in our study were younger then 12 months. Approximately the same was the number of children 13-24 months (33 patients or 31.43%) and 25-60 months (32 patients or 30.43%). The mean value of PRC in children with viral diarrhea was 0.13±0.5 ng/mL in children with bacterial diarrhea was 5.3±4.9 ng/m Land in children with extra intestinal diarrhea was 1.7±2.8 ng/mL. When measured using ANOVA and Turkey HSD tests, results have shown the statistical significance when comparing viral with bacterial and extra intestinal diarrhea but were statistically insignificant when comparing bacterial and extra intestinal diarrhea. Conclusion: Procalcitonin is an important but not conclusive marker of bacterial etiology of acute diarrhea in children younger than 5 years. PMID:24944526

  14. Sensitivity and specificity of procalcitonin to determine etiology of diarrhea in children younger than 5 years.

    Science.gov (United States)

    Ismaili-Jaha, Vlora; Shala, Mujë; Azemi, Mehmedali; Spahiu, Shqipe; Hoxha, Teuta; Avdiu, Muharrem; Spahiu, Lidvana

    2014-04-01

    The aim of this study is to assess the sensitivity and specificity of procalcitonin to determine bacterial etiology of diarrhea. For this purpose we conducted the study comprising 115 children aged 1 to 60 months admitted at the Department of Pediatric Gastroenterology, Pediatric Clinic, divided in three groups based on etiology of the diarrhea that has been confirmed with respective tests during the hospitalization. Each group has equal number of patients - 35. The first group was confirmed to have bacterial diarrhea, the second viral diarrhea and the third extra intestinal diarrhea. The determination of procalcitonin has been established with the ELFA methods of producer B.R.A.H.M.S Diagnostica GmbH, Berlin, (Germany). From the total number of 1130 patient with acute diarrhea procalcitonin was assessed in 105. 67 (63.8%) of these patient were male. More than one third (38.14%) of the children in our study were younger then 12 months. Approximately the same was the number of children 13-24 months (33 patients or 31.43%) and 25-60 months (32 patients or 30.43%). The mean value of PRC in children with viral diarrhea was 0.13±0.5 ng/mL in children with bacterial diarrhea was 5.3±4.9 ng/m Land in children with extra intestinal diarrhea was 1.7±2.8 ng/mL. When measured using ANOVA and Turkey HSD tests, results have shown the statistical significance when comparing viral with bacterial and extra intestinal diarrhea but were statistically insignificant when comparing bacterial and extra intestinal diarrhea. Procalcitonin is an important but not conclusive marker of bacterial etiology of acute diarrhea in children younger than 5 years.

  15. Atomic absorption determination of ultratrace tellurium in rocks utilizing high sensitivity sampling systems

    International Nuclear Information System (INIS)

    Beaty, R.D.

    1973-01-01

    The sampling boat and the graphite furnace were shown to possess the required sensitivity to detect tellurium at ultratrace levels, in a variety of sample types, by atomic absorption. In the sampling boat approach, tellurium in sample solutions is chemically separated and concentrated by extraction into methyl isobutyl ketone before measurement. For samples exhibiting extraction interferences or excessively high background absorption, a preliminary separation of tellurium by coprecipitation with selenium is described. Using this technique, tellurium can be quantitatively detected down to 5 nanograms and linear response is observed to 100 nanograms. Relative standard deviations of better than 7 percent are achieved for 50 nanograms of tellurium. For samples that have a tellurium content below the detection limits of the sampling boat, the graphite furnace is used for atomization. By this method, as little as 0.07 nanograms of tellurium can be detected, and a precision of 1 percent relative standard deviation is achievable at the 5 nanogram level. A routinely applicable procedure was developed for determining tellurium in rocks, using the graphite furnace, after a hydrofluoric acid decomposition of the sample. Using this procedure, tellurium data were obtained on 20 different rocks, and the significance of this new information is discussed. (Diss. Abstr. Int., B)

  16. Luminol Chemiluminescence Catalyzed by Silver Nanoparticles for the Sensitive Determination of Penicillamine

    Directory of Open Access Journals (Sweden)

    Fakhr Eldin O. Suliman

    2018-01-01

    Full Text Available A sequential injection method for the determination of penicillamine (PA was developed based on quenching the chemiluminescence generated by oxidation of luminol by hydrogen peroxide in presence of silver nanoparticles (AgNPs. The chemiluminescence (CL of the reaction was found to greatly enhance in presence of AgNPs due to the increased catalyst surface area. The method was sensitive and found suitable for analysis of penicillamine in pharmaceutical preparations. Linear calibration curve is obtained in the range 0.2-1.0 mg mL-1 with a relative standard deviation less than 2%. A recovery percent of 102.3 ±0.2 was obtained with the tablets matrix indicating reasonable selectivity of the method for PA in tablets. The mechanism of quenching of the CL reaction was investigated by UV-Visible spectroscopy and transmission electron microscopy as well as by theoretical calculations using DFT-B3LYP method. The covalent attachment of PA to the AgNPs triggers aggregation of the particles thereby diminishing the surface significantly. The method was applied for the assay of PA in pharmaceutical preparations.

  17. Direct determination of graphene quantum dots based on terbium-sensitized luminescence

    Science.gov (United States)

    Llorent-Martínez, Eulogio J.; Molina-García, Lucía; Durán, Gema M.; Ruiz-Medina, Antonio; Ríos, Ángel

    2018-06-01

    Graphene quantum dots (GQD) were determined in water samples using terbium-sensitized luminescence (TSL). Terbium ions complex with GQD due to the carboxylic groups that are usually present in these nanomaterials, increasing the luminescence signal of terbium. In Tb(III)-GQD complexes, GQD absorb energy at their characteristic excitation wavelength and transfer it to terbium ion, which emits at its particular emission wavelength. The analytical signal, measured at λexc = 257 nm and λem = 545 nm, increases proportionally to GQD concentration between 50 and 500 μg L-1. Under optimum conditions, the proposed method presents a detection limit of 15 μg L-1 and is selective to GQD in the presence of other nanomaterials of similar size. As GQD are highly water-soluble, they are potential contaminants in environmental or drinking waters water samples, and hence the method was applied to the analysis of different drinking waters which were the target samples for the application of the developed method.

  18. A sensitive spectrophotometric determination of nitrogen dioxide in the working atmosphere

    Directory of Open Access Journals (Sweden)

    Prachi Parmar

    2009-12-01

    Full Text Available In the present investigation, a simple and sensitive spectrophotometric method for the determination of nitrogen dioxide in various environmental samples is described. Nitrogen dioxide in air was fixed as nitrite ion in alkaline sodium arsenite absorbing solution. The nitrite formed was diazotized with p−aminoacetophenone in acidic medium which was subsequently coupled with phloroglucinol to give yellow−orange dye in alkaline medium having an absorption maximum at 420 nm. Beer’s law was obeyed in the range of 0.008 − 0.12 μg mL-1 of nitrogen dioxide and has a molar absorptivity of 2.875 x 105 L mol-1 cm-1. Optimum reaction conditions for diazotization, full colour development and the effect of variables like temperature, time and pH have been studied. Detailed studies to check the collection efficiency and NO2:NO2- stoichiometric ratio has been carried out. The reaction has been successfully applied for the detection of nitrogen dioxide in cigarette smoke, scooter exhaust, and workroom air.

  19. Determination of baroreflex sensitivity during the modified Oxford maneuver by trigonometric regressive spectral analysis.

    Directory of Open Access Journals (Sweden)

    Julia Gasch

    Full Text Available BACKGROUND: Differences in spontaneous and drug-induced baroreflex sensitivity (BRS have been attributed to its different operating ranges. The current study attempted to compare BRS estimates during cardiovascular steady-state and pharmacologically stimulation using an innovative algorithm for dynamic determination of baroreflex gain. METHODOLOGY/PRINCIPAL FINDINGS: Forty-five volunteers underwent the modified Oxford maneuver in supine and 60° tilted position with blood pressure and heart rate being continuously recorded. Drug-induced BRS-estimates were calculated from data obtained by bolus injections of nitroprusside and phenylephrine. Spontaneous indices were derived from data obtained during rest (stationary and under pharmacological stimulation (non-stationary using the algorithm of trigonometric regressive spectral analysis (TRS. Spontaneous and drug-induced BRS values were significantly correlated and display directionally similar changes under different situations. Using the Bland-Altman method, systematic differences between spontaneous and drug-induced estimates were found and revealed that the discrepancy can be as large as the gain itself. Fixed bias was not evident with ordinary least products regression. The correlation and agreement between the estimates increased significantly when BRS was calculated by TRS in non-stationary mode during the drug injection period. TRS-BRS significantly increased during phenylephrine and decreased under nitroprusside. CONCLUSIONS/SIGNIFICANCE: The TRS analysis provides a reliable, non-invasive assessment of human BRS not only under static steady state conditions, but also during pharmacological perturbation of the cardiovascular system.

  20. Determining the sensitivity of Data Envelopment Analysis method used in airport benchmarking

    Directory of Open Access Journals (Sweden)

    Mircea BOSCOIANU

    2013-03-01

    Full Text Available In the last decade there were some important changes in the airport industry, caused by the liberalization of the air transportation market. Until recently airports were considered infrastructure elements, and they were evaluated only by traffic values or their maximum capacity. Gradual orientation towards commercial led to the need of finding another ways of evaluation, more efficiency oriented. The existing methods for assessing efficiency used for other production units were not suitable to be used in case of airports due to specific features and high complexity of airport operations. In the last years there were some papers that proposed the Data Envelopment Analysis as a method for assessing the operational efficiency in order to conduct the benchmarking. This method offers the possibility of dealing with a large number of variables of different types, which represents the main advantage of this method and also recommends it as a good benchmarking tool for the airports management. This paper goal is to determine the sensitivity of this method in relation with its inputs and outputs. A Data Envelopment Analysis is conducted for 128 airports worldwide, in both input- and output-oriented measures, and the results are analysed against some inputs and outputs variations. Possible weaknesses of using DEA for assessing airports performance are revealed and analysed against this method advantages.

  1. Determination of the Antares sensitivity to the cosmic neutrinos diffuse flux using contained showers

    International Nuclear Information System (INIS)

    Denans, D.

    2006-12-01

    The Antares collaboration has chosen to build an underwater telescope in the Mediterranean sea, at a depth of 2500 m, to detect high energy (> 100 GeV) cosmic neutrinos. This detector is composed of 12 vertical lines with 900 photomultipliers. Neutrinos are detected thanks to the Cherenkov light produced in water by charged particles created in neutrino interactions near the detector. The aim of this work is the study of Antares performance for the detection of the electronic neutrino interaction in the instrumented volume using a Monte-Carlo simulation. The method allows the determination of the incident energy with an excellent resolution (20 %) which is much smaller than what is obtained from muons induced by muonic neutrino interactions at several kilometers below the detector. This work has consisted in studying the reconstruction of contained showers of particles in the detector resulting from charged current interactions of electronic neutrinos. This mode of detection has been used for the study of the diffuse neutrino flux, resulting from the neutrino emission of unresolved sources and that can be isolated from the atmospheric neutrino background at high energy. The Antares sensitivity is found to be 5.10 -7 GeV.cm -2 .s -1 .sr -1 after 1 year of data recording for energies above 3 TeV and for a model with an E -2 energy spectrum. (author)

  2. Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

    International Nuclear Information System (INIS)

    Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

    2014-01-01

    In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

  3. The optimal condition of performing MTT assay for the determination of radiation sensitivity

    International Nuclear Information System (INIS)

    Hong, Semie; Kim, Il Han

    2001-01-01

    The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Four human cancer cell lines - PCI-1, SNU-1066, NCI-H63O and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy, For clonogenic assay, cells in 25 cm 2 flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10-14 days, For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R 2 value of 0.975-0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was alter 6

  4. Sensitivity of Attitude Determination on the Model Assumed for ISAR Radar Mappings

    Science.gov (United States)

    Lemmens, S.; Krag, H.

    2013-09-01

    Inverse synthetic aperture radars (ISAR) are valuable instrumentations for assessing the state of a large object in low Earth orbit. The images generated by these radars can reach a sufficient quality to be used during launch support or contingency operations, e.g. for confirming the deployment of structures, determining the structural integrity, or analysing the dynamic behaviour of an object. However, the direct interpretation of ISAR images can be a demanding task due to the nature of the range-Doppler space in which these images are produced. Recently, a tool has been developed by the European Space Agency's Space Debris Office to generate radar mappings of a target in orbit. Such mappings are a 3D-model based simulation of how an ideal ISAR image would be generated by a ground based radar under given processing conditions. These radar mappings can be used to support a data interpretation process. E.g. by processing predefined attitude scenarios during an observation sequence and comparing them with actual observations, one can detect non-nominal behaviour. Vice versa, one can also estimate the attitude states of the target by fitting the radar mappings to the observations. It has been demonstrated for the latter use case that a coarse approximation of the target through an 3D-model is already sufficient to derive the attitude information from the generated mappings. The level of detail required for the 3D-model is determined by the process of generating ISAR images, which is based on the theory of scattering bodies. Therefore, a complex surface can return an intrinsically noisy ISAR image. E.g. when many instruments on a satellite are visible to the observer, the ISAR image can suffer from multipath reflections. In this paper, we will further analyse the sensitivity of the attitude fitting algorithms to variations in the dimensions and the level of detail of the underlying 3D model. Moreover, we investigate the ability to estimate the orientations of different

  5. Increase of radiation damage to potassium-ion permeability in E. coli cells with decrease in membrane fluidity

    International Nuclear Information System (INIS)

    Suzuki, S.

    1980-01-01

    Membrane lipids of an auxotroph of E. coli requiring unsaturated fatty acid were manipulated by supplementing the growth medium with unsaturated fatty acids of different chain lengths and/or configurations, and the radiation damage to K + -permeability of the resulting modified cells was investigated in relation with factors influencing membrane fluidity, such as temperature and procaine. Radiation had greater effects on membranes supplemented with unsaturated fatty acids of the trans configuration with a longer chain than on those of the cis configuration with a shorter chain. Radiation damage also increased with decrease in temperature. Furthermore, procaine-treated membranes showed increased resistance to radiation. All these results indicate that the damage was affected by the physical character of membrane lipids and that it was greater in membranes with decreased fluidity. (author)

  6. Effects of minor scandium on as-cast microstructure, mechanical properties and casting fluidity of ZA84 magnesium alloy

    International Nuclear Information System (INIS)

    Pan Fusheng; Yang Mingbo; Cheng Liang

    2010-01-01

    The effects of minor Sc on the as-cast microstructure, mechanical properties and casting fluidity of the ZA84 magnesium alloy were investigated. The results indicate that the Mg 32 (Al,Zn) 49 phase in the ZA84 alloy is refined with the addition of 0.12-0.35 wt.% Sc, and the formation of the Mg 32 (Al,Zn) 49 phase is suppressed. An increase in Sc amount from 0.12 wt.% to 0.35 wt.% causes the morphology of the Mg 32 (Al,Zn) 49 phase to gradually change from coarse continuous and/or quasi-continuous net to relatively fine quasi-continuous and/or disconnected shapes. In addition, it is shown that the tensile and creep properties of the ZA84 alloy are improved, but the casting fluidity of the alloy is decreased with the addition of 0.12-0.35 wt.% Sc.

  7. "It Has No Color, It Has No Gender, It's Gender Bending": Gender and Sexuality Fluidity and Subversiveness in Drag Performance.

    Science.gov (United States)

    Egner, Justine; Maloney, Patricia

    2016-07-01

    Gender identity is a key question for drag performers. Previous research has shown a lack of consensus about the subversiveness and gender fluidity of drag performers. This article examines the question: How does the relationship between performers and their audience affect the subversive nature and gender representation of drag performers in this study? Furthermore, is this relationship complicated by sexuality? This study uses ethnographic and interview methods, examining experiences of 10 drag performers. Findings indicate mutuality in the relationship between performers and audience. The recursiveness of this relationship provides a constant feedback to the performers in their effort to displace the audience's previously held notions. The performers have fluid understandings of gender and sexuality, often presenting multiple genders in and out of drag. Interactions between performers and their audience indicate their belief in gender fluidity; moreover, the drag performers themselves desire to be subversive and gender and sexually fluid.

  8. Recycling of tailings from Korea Molybdenum Corporation as admixture for high-fluidity concrete.

    Science.gov (United States)

    Jung, Moon Young; Choi, Yun Wang; Jeong, Jae Gwon

    2011-01-01

    The main objective of this study is to develop an eco-friendly and a large recycling technique of flotation Tailings from korea (TK) from metal mines as construction materials such as admixtures for high-fluidity concrete (HFC). TK used in this study was obtained from the Korea Molybdenum Corporation in operation. TK was used as the alternative material to adjust flowability and viscosity of HFC in the form of powder agent which enables adjustment of concrete compressive strength. In this study, we have performed concrete rheological tests and concrete flowability tests to obtain the quality characteristics of TK for using as the admixture in producing HFC. The results indicated that the adequate mix ratio of cement to TK should be 8:2 (vol%). It is more effective to use the TK as admixture to control flowability, viscosity and strength of HFC than the normal concrete. It was found that TK could be recycled construction materials in bulk such as admixture for HFC, in terms of the economic and eco-friendly aspects.

  9. Enhanced fluidity liquid chromatography of inulin fructans using ternary solvent strength and selectivity gradients.

    Science.gov (United States)

    Bennett, Raffeal; Olesik, Susan V

    2018-01-25

    The value of exploring selectivity and solvent strength ternary gradients in enhanced fluidity liquid chromatography (EFLC) is demonstrated for the separation of inulin-type fructans from chicory. Commercial binary pump systems for supercritical fluid chromatography only allow for the implementation of ternary solvent strength gradients which can be restrictive for the separation of polar polymeric analytes. In this work, a custom system was designed to extend the capability of EFLC to allow tuning of selectivity or solvent strength in ternary gradients. Gradient profiles were evaluated using the Berridge function (RF 1 ), normalized resolution product (NRP), and gradient peak capacity (P c ). Selectivity gradients provided the separation of more analytes over time. The RF 1 function showed favor to selectivity gradients with comparable P c to that of solvent strength gradients. NRP did not strongly correlate with P c or RF 1 score. EFLC with the hydrophilic interaction chromatography, HILIC, separation mode was successfully employed to separate up to 47 fructan analytes in less than 25 min using a selectivity gradient. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Radiation killing of E. coli K1060: role of membrane fluidity, hypothermia and local anaesthetics

    International Nuclear Information System (INIS)

    Yatvin, M.B.; Schmitz, B.J.; Dennis, W.H.

    1980-01-01

    The enhancement of killing by γ irradiation, which is seen when E. coliK1060 are cooled below the transition temperature of their membrane lipids, is blocked by procaine-HCl. These data are consistent with the hypothesis that increased killing associated with irradiation at 0 0 C is the result of membrane microviscosity increases, since procaine is known to fluidize membranes. A cooling enhancement ratio (c.e.r.) is defined as the ratio of radiation D 0 at 22 0 C to its value at 0 0 C. The c.e.r. for oxygen-bubbled cells is 1.5 and for nitrogen-bubbled cells is 2.1. In the presence of 25mM procaine the respective c.e.r. values are 1.08 and 1.29. The oxygen enhancement ratio (o.e.r.) at 22 0 C is 3.43 and at 0 0 C is 2.45. The addition of procaine does not change the o.e.r. Thus, the temperature effect on o.e.r. does not appear to be related to membrane fluidity. (author)

  11. Comparison on Heat of Hydration between Current Concrete for NPP and High Fluidity Concrete including Pozzolan Powders

    International Nuclear Information System (INIS)

    Noh, Jea Myoung; Cho, Myung Sug

    2010-01-01

    Nuclear power plant (NPP) concrete structures are exposed to many construction factors that lower the quality of concrete due to densely packed reinforcements and heat of hydration since they are mostly constructed with mass concrete. The concrete currently being used in Korean NPPs is mixed with Type I cement and fly ash. However, there is a demand to improve the performance of concrete with reduced heat of hydration and superior constructability. Many advantages such as improving workability and durability of concrete and decreasing heat of hydration are introduced by replacing cement with pozzolan binders. Therefore, the manufacturing possibility of high fluidity concrete should be investigated through applying multi-component powders blended with pozzolan binders to the concrete structure of NPPs, while the researches on properties, characteristic of hydration, durability and long-term behavior of high fluidity concrete using multi-component cement should be carried out. High fluidity concrete which is made using portland cement and pozzlonan powders such as fly ash and blast furnace slag has better properties on heat of hydration than the concrete currently in use for NPPs

  12. Effect of reinforcement amount, mold temperature, superheat, and mold thickness on fluidity of in-situ Al-Mg2Si composites

    Directory of Open Access Journals (Sweden)

    Reza Vatankhah Barenji

    2018-01-01

    Full Text Available In the present study, the effects of mold temperature, superheat, mold thickness, and Mg2Si amount on the fluidity of the Al-Mg2Si as-cast in-situ composites were investigated using the mathematical models. Composites with different amounts of Mg2Si were fabricated, and the fluidity and microstructure of each were then analyzed. For this purpose, the experiments were designed using a central composite rotatable design, and the relationship between parameters and fluidity were developed using the response surface method. In addition, optical and scanning electron microscopes were used for microstructural observation. The ANOVA shows that the mathematical models can predict the fluidity accurately. The results show that by increasing the mold temperature from 25 °C to 200 °C, superheat from 50 °C to 250 °C, and thickness from 3 mm to 12 mm, the fluidity of the composites decreases, where the mold thickness is more effective than other factors. In addition, the higher amounts of Mg2Si in the range from 15wt.% to 25wt.% lead to the lower fluidity of the composites. For example, when the mold temperature, superheat, and thickness are respectively 100 °C, 150 °C, and 7 mm, the fluidity length is changed in the range of 11.9 cm to 15.3 cm. By increasing the amount of Mg2Si, the morphology of the primary Mg2Si becomes irregular and the size of primary Mg2Si is increased. Moreover, the change of solidification mode from skin to pasty mode is the most noticeable microstructural effect on the fluidity.

  13. IgE sensitization and sociodemographic conditions as determinant factors in asthma severity

    Directory of Open Access Journals (Sweden)

    Rodrigo Gaviria

    2017-12-01

    Full Text Available Background: In Latin America there are few data about the factors that influence the control and severity of asthma. Objective: To describe the association between IgE sensitization to intra-home allergens and housing conditions in the severity of asthma. Methods: Sensitization to aero-allergens was evaluated by skin prick test and socio-demographic data by a questionnaire in a population between 6 and 14 years of age with diagnosis of asthma. Asthma control was measured according to spirometric results and to the application of the ACT (Asthma Control Test; the severity and symptom control was evaluated according to the GINA guideline. Results: A total of 150 resident patients from the Aburra Valley (Colombia were included. The median age of participants was 11 years, 95 (63.3 % male. 92 % of the patients resided in the urban area. Mite sensitization was the most prevalent in controlled and uncontrolled patients. Sensitization to cockroach and some poverty conditions were risk factors for asthma severity. Conclusion: Poverty conditions appear to favor the development of severe asthma and in turn IgE sensitization to cockroaches. This sensitization could serve as a biomarker of severity.

  14. Barium enema and endoscopy for the detection of colorectal neoplasia: Sensitivity, specificity, complications and its determinants

    International Nuclear Information System (INIS)

    Zwart, Ingrid M. de; Griffioen, Gerrit; Shaw, M. Pertaap Chandie; Lamers, Cornelis B.H.W.; Roos, Albert de

    2001-01-01

    AIM: To analyse sensitivity, specificity and complication rate of endoscopy, and barium enema for the detection of colorectal neoplasia. MATERIALS AND METHODS: A MEDLINE search was performed (1980-2000) directed at the endoscopic and radiologic literature on barium enema. Articles were selected based on the type of study, availability of sensitivity and specificity values in sizeable patient groups, and reports on complications. Sixty articles were included in the analysis. RESULTS: Endoscopy proved to have superior sensitivity for polyps in patients at high-risk for colorectal neoplasia. The role of endoscopy and radiology in average-risk screening populations is not known. Sensitivity and specificity rates ranged widely, probably due to bias. For the detection of small polyps endoscopy has superior performance, whereas sensitivity is similar for endoscopy and barium enema for the detection of larger (>1 cm) polyps and tumours. Overall, endoscopy is associated with a higher complication rate. CONCLUSION: Endoscopy is the preferred detection method in high-risk patients. The role of endoscopy and radiology in a screening setting requires evaluation. This review provides the test characteristics of endoscopy and radiology which are relevant for a cost-effectiveness analysis. Double-contrast barium enema may play an important role for screening purposes, owing to its good sensitivity for detecting larger (>1 cm) polyps and its lack of major complications. Zwart, I.M. de et al. (2001)

  15. Sensitive and selective determination of fluvoxamine maleate using a sensitive chemiluminescence system based on the alkaline permanganate-Rhodamine B-gold nanoparticles reaction.

    Science.gov (United States)

    Hassanzadeh, Javad; Amjadi, Mohammad

    2015-06-01

    A high-yield chemiluminescence (CL) system based on the alkaline permanganate-Rhodamine B reaction was developed for the sensitive determination of fluvoxamine maleate (Flu). Rhodamine B is oxidized by alkaline KMnO4 and a weak CL emission is produced. It was demonstrated that gold nanoparticles greatly enhance this CL emission due to their interaction with Rhodamine B molecules. It is also observed that sodium dodecyl sulfate, an anionic surfactant, can strongly increase this enhancement. In addition, it was demonstrated that a notable decrease in the CL intensity is observed in the presence of Flu. This may be related to Flu oxidation with KMnO4 . There is a linear relationship between the decrease in CL intensity and the Flu concentration over a range of 2-300 µg/L. A new simple, rapid and sensitive CL method was developed for the determination of Flu with a detection limit (3s) of 1.35 µg/L. The proposed method was used for the determination of Flu in pharmaceutical and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Sensitivity Analysis of the USLE Soil Erodibility Factor to Its Determining Parameters

    Science.gov (United States)

    Mitova, Milena; Rousseva, Svetla

    2014-05-01

    Soil erosion is recognized as one of the most serious soil threats worldwide. Soil erosion prediction is the first step in soil conservation planning. The Universal Soil Loss Equation (USLE) is one of the most widely used models for soil erosion predictions. One of the five USLE predictors is the soil erodibility factor (K-factor), which evaluates the impact of soil characteristics on soil erosion rates. Soil erodibility nomograph defines K-factor depending on soil characteristics, such as: particle size distribution (fractions finer that 0.002 mm and from 0.1 to 0.002 mm), organic matter content, soil structure and soil profile water permeability. Identifying the soil characteristics, which mostly influence the K-factor would give an opportunity to control the soil loss through erosion by controlling the parameters, which reduce the K-factor value. The aim of the report is to present the results of analysis of the relative weight of these soil characteristics in the K-factor values. The relative impact of the soil characteristics on K-factor was studied through a series of statistical analyses of data from the geographic database for soil erosion risk assessments in Bulgaria. Degree of correlation between K-factor values and the parameters that determine it was studied by correlation analysis. The sensitivity of the K-factor was determined by studying the variance of each parameter within the range between minimum and maximum possible values considering average value of the other factors. Normalizing transformation of data sets was applied because of the different dimensions and the orders of variation of the values of the various parameters. The results show that the content of particles finer than 0.002 mm has the most significant relative impact on the soil erodibility, followed by the content of particles with size from 0.1 mm to 0.002 mm, the class of the water permeability of the soil profile, the content of organic matter and the aggregation class. The

  17. Fluorimetry as a Simple and Sensitive Method for Determination of Catalase

    Directory of Open Access Journals (Sweden)

    Mehdi Hedayati

    2014-02-01

    Full Text Available Background: Catalase enzyme plays an important role in the anti-oxidation defense of body so it is important to measure its activity. Nowadays catalase activity measurement is performed by expensive imported kits in various scientific fields. The purpose of this study was to design a sensitive fluorimetry method for measuring catalase activity with improved sensitivity, accuracy and speed. Materials and Methods: In this study, the reaction of hydrogen peroxide with peroxidase (as a reaction accelerator was used in fluorimetry for catalase activity measuring in serum samples in order to increase the sensitivity of the assay. The sensitivity and intra- and inter-assay accuracy, verification test, recovery and parallelism tests, comparison method and correlation and coherence investigation methods were also performed. In order to increase the accuracy and speed of reading, the assay was performed in microplates and reading was done in fluorimetry plates. Results: The percentage of intra- and inter-assay variation coefficients were measured 3.8- 6.6 % and 4.1-7.3%, respectively. Comparison of the results of mentioned method for 50 serum samples with common colorimetric method showed a good correlation (0.917. In assessing the accuracy, the recovery percent was obtained 91% to 107%. The test sensitivity was measured 0.02 IU/ml. Conclusion: The fluorimetry method by microplate reading has a sufficient precision, accuracy and efficiency for catalase activity measuring as well as speed of measurement. Thus it can be an alternative method to conventional imported colorimetric methods.

  18. Metabolic determinants of cancer cell sensitivity to glucose limitation and biguanides

    Science.gov (United States)

    Birsoy, Kıvanç; Possemato, Richard; Lorbeer, Franziska K.; Bayraktar, Erol C.; Thiru, Prathapan; Yucel, Burcu; Wang, Tim; Chen, Walter W.; Clish, Clary B.; Sabatini, David M.

    2014-04-01

    As the concentrations of highly consumed nutrients, particularly glucose, are generally lower in tumours than in normal tissues, cancer cells must adapt their metabolism to the tumour microenvironment. A better understanding of these adaptations might reveal cancer cell liabilities that can be exploited for therapeutic benefit. Here we developed a continuous-flow culture apparatus (Nutrostat) for maintaining proliferating cells in low-nutrient media for long periods of time, and used it to undertake competitive proliferation assays on a pooled collection of barcoded cancer cell lines cultured in low-glucose conditions. Sensitivity to low glucose varies amongst cell lines, and an RNA interference (RNAi) screen pinpointed mitochondrial oxidative phosphorylation (OXPHOS) as the major pathway required for optimal proliferation in low glucose. We found that cell lines most sensitive to low glucose are defective in the OXPHOS upregulation that is normally caused by glucose limitation as a result of either mitochondrial DNA (mtDNA) mutations in complex I genes or impaired glucose utilization. These defects predict sensitivity to biguanides, antidiabetic drugs that inhibit OXPHOS, when cancer cells are grown in low glucose or as tumour xenografts. Notably, the biguanide sensitivity of cancer cells with mtDNA mutations was reversed by ectopic expression of yeast NDI1, a ubiquinone oxidoreductase that allows bypass of complex I function. Thus, we conclude that mtDNA mutations and impaired glucose utilization are potential biomarkers for identifying tumours with increased sensitivity to OXPHOS inhibitors.

  19. Exposure levels, determinants and IgE mediated sensitization to bovine allergens among Danish farmers and non-farmers

    NARCIS (Netherlands)

    Schlünssen, V; Basinas, I; Zahradnik, E; Elholm, G; Wouters, I M; Kromhout, H; Heederik, D; Bolund, A C S; Omland, Ø; Raulf, M; Sigsgaard, T

    BACKGROUND: Bovine allergens can induce allergic airway diseases. High levels of allergens in dust from stables and homes of dairy farmers have been reported, but sparse knowledge about determinants for bovine allergen levels and associations between exposure level and sensitization is available.

  20. Quantitative method to determine the regional drinking water odorant regulation goals based on odor sensitivity distribution: illustrated using 2-MIB.

    Science.gov (United States)

    Yu, Jianwei; An, Wei; Cao, Nan; Yang, Min; Gu, Junong; Zhang, Dong; Lu, Ning

    2014-07-01

    Taste and odor (T/O) in drinking water often cause consumer complaints and are thus regulated in many countries. However, people in different regions may exhibit different sensitivities toward T/O. This study proposed a method to determine the regional drinking water odorant regulation goals (ORGs) based on the odor sensitivity distribution of the local population. The distribution of odor sensitivity to 2-methylisoborneol (2-MIB) by the local population in Beijing, China was revealed by using a normal distribution function/model to describe the odor complaint response to a 2-MIB episode in 2005, and a 2-MIB concentration of 12.9 ng/L and FPA (flavor profile analysis) intensity of 2.5 was found to be the critical point to cause odor complaints. Thus the Beijing ORG for 2-MIB was determined to be 12.9 ng/L. Based on the assumption that the local FPA panel can represent the local population in terms of sensitivity to odor, and that the critical FPA intensity causing odor complaints was 2.5, this study tried to determine the ORGs for seven other cities of China by performing FPA tests using an FPA panel from the corresponding city. ORG values between 12.9 and 31.6 ng/L were determined, showing that a unified ORG may not be suitable for drinking water odor regulations. This study presents a novel approach for setting drinking water odor regulations. Copyright © 2014. Published by Elsevier B.V.

  1. Maternal nutritional state determines the sensitivity of Daphnia magna offspring to Fenvalerate pulse exposure.

    NARCIS (Netherlands)

    Pieters, B.J.; Liess, M.

    2006-01-01

    Abstract Daphnia populations in the field suffer periodic natural stress conditions such as low food levels. It is known that at low nutritional supply, Daphnia produces fewer but larger offspring, which are acutely less sensitive to chemical stress. We hypothesized that the change in the

  2. Determination of the thermal and epithermal neutron sensitivities of an LBO chamber

    Energy Technology Data Exchange (ETDEWEB)

    Endo, Satoru; Kotani, Kei; Kajimoto, Tsuyoshi; Tanaka, Kenichi [Hiroshima University, Quantum Energy Applications, Graduate School of Engineering, Higashi-Hiroshima (Japan); Sato, Hitoshi; Nakajima, Erika [Ibaraki Prefectural University of Health Science, Radiological Sciences, Ibaraki (Japan); Shimazaki, Takuto [Hiroshima University, Quantum Energy Applications, Graduate School of Engineering, Higashi-Hiroshima (Japan); Delta Kogyo Co., Ltd., Hiroshima (Japan); Suda, Mitsuru; Hamano, Tsuyoshi [National Institute of Radiological Sciences, Chiba-Shi, Chiba (Japan); Hoshi, Masaharu [Hiroshima University, Institute for Peace Science, Hiroshima (Japan)

    2017-08-15

    An LBO (Li{sub 2}B{sub 4}O{sub 7}) walled ionization chamber was designed to monitor the epithermal neutron fluence in boron neutron capture therapy clinical irradiation. The thermal and epithermal neutron sensitivities of the device were evaluated using accelerator neutrons from the {sup 9}Be(d, n) reaction at a deuteron energy of 4 MeV (4 MeV d-Be neutrons). The response of the chamber in terms of the electric charge induced in the LBO chamber was compared with the thermal and epithermal neutron fluences measured using the gold-foil activation method. The thermal and epithermal neutron sensitivities obtained were expressed in units of pC cm{sup 2}, i.e., from the chamber response divided by neutron fluence (cm{sup -2}). The measured LBO chamber sensitivities were 2.23 x 10{sup -7} ± 0.34 x 10{sup -7} (pC cm{sup 2}) for thermal neutrons and 2.00 x 10{sup -5} ± 0.12 x 10{sup -5} (pC cm{sup 2}) for epithermal neutrons. This shows that the LBO chamber is sufficiently sensitive to epithermal neutrons to be useful for epithermal neutron monitoring in BNCT irradiation. (orig.)

  3. Determination of IgE antibodies to the benzylpenicilloyl determinant: a comparison of the sensitivity and specificity of three radio allergo sorbent test methods.

    Science.gov (United States)

    Garcia, J J; Blanca, M; Moreno, F; Vega, J M; Mayorga, C; Fernandez, J; Juarez, C; Romano, A; de Ramon, E

    1997-01-01

    The quantitation of in vitro IgE antibodies to the benzylpenicilloyl determinant (BPO) is a useful tool for evaluating suspected penicillin allergic subjects. Although many different methods have been employed, few studies have compared their diagnostic specificity and sensitivity. In this study, the sensitivity and specificity of three different radio allergo sorbent test (RAST) methods for quantitating specific IgE antibodies to the BPO determinant were compared. Thirty positive control sera (serum samples from penicillin allergic subjects with a positive clinical history and a positive penicillin skin test) and 30 negative control sera (sera from subjects with no history of penicillin allergy and negative skin tests) were tested for BPO-specific IgE antibodies by RAST using three different conjugates coupled to the solid phase: benzylpenicillin conjugated to polylysine (BPO-PLL), benzylpenicillin conjugated to human serum albumin (BPO-HSA), and benzylpenicillin conjugated to an aminospacer (BPO-SP). Receiver operator control curves (ROC analysis) were carried out by determining different cut-off points between positive and negative values. Contingence tables were constructed and sensitivity, specificity, negative predictive values (PV-), and positive predictive values (PV+) were calculated. Pearson correlation coefficients (r) and intraclass correlation coefficients (ICC) were determined and the differences between methods were compared by chi 2 analysis. Analysis of the areas defined by the ROC curves showed statistical differences among the three methods. When cut-off points for optimal sensitivity and specificity were chosen, the BPO-HSA assay was less sensitive and less specific and had a lower PV- and PV+ than the BPO-PLL and BPO-SP assays. Assessment of r and ICC indicated that the correlation was very high, but the concordance between the PLL and SP methods was higher than between the PLL and HSA or SP and HSA methods. We conclude that for quantitating Ig

  4. The adipose transcriptional response to insulin is determined by obesity, not insulin sensitivity

    DEFF Research Database (Denmark)

    Rydén, Mikael; Hrydziuszko, Olga; Mileti, Enrichetta

    2016-01-01

    Metabolically healthy obese subjects display preserved insulin sensitivity and a beneficial white adipose tissue gene expression pattern. However, this observation stems from fasting studies when insulin levels are low. We investigated adipose gene expression by 5'Cap-mRNA sequencing in 17 healthy...... non-obese (NO), 21 insulin-sensitive severely obese (ISO), and 30 insulin-resistant severely obese (IRO) subjects, before and 2 hr into a hyperinsulinemic euglycemic clamp. ISO and IRO subjects displayed a clear but globally similar transcriptional response to insulin, which differed from the small...... effects observed in NO subjects. In the obese, 231 genes were altered; 71 were enriched in ISO subjects (e.g., phosphorylation processes), and 52 were enriched in IRO subjects (e.g., cellular stimuli). Common cardio-metabolic risk factors and gender do not influence these findings. This study demonstrates...

  5. Optimal Testing Intervals in the Squatting Test to Determine Baroreflex Sensitivity

    OpenAIRE

    Ishitsuka, S.; Kusuyama, N.; Tanaka, M.

    2014-01-01

    The recently introduced “squatting test” (ST) utilizes a simple postural change to perturb the blood pressure and to assess baroreflex sensitivity (BRS). In our study, we estimated the reproducibility of and the optimal testing interval between the STs in healthy volunteers. Thirty-four subjects free of cardiovascular disorders and taking no medication were instructed to perform the repeated ST at 30-sec, 1-min, and 3-min intervals in duplicate in a random sequence, while the systolic blood p...

  6. A simple and inexpensive method for determining cold sensitivity and adaptation in mice.

    Science.gov (United States)

    Brenner, Daniel S; Golden, Judith P; Vogt, Sherri K; Gereau, Robert W

    2015-03-17

    Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity. Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 °C to 5 °C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above. This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

  7. Determination of Chlorinated Hydrocarbons in Water Using Highly Sensitive Mid-Infrared Sensor Technology

    Science.gov (United States)

    Lu, Rui; Mizaikoff, Boris; Li, Wen-Wei; Qian, Chen; Katzir, Abraham; Raichlin, Yosef; Sheng, Guo-Ping; Yu, Han-Qing

    2013-08-01

    Chlorinated aliphatic hydrocarbons and chlorinated aromatic hydrocarbons (CHCs) are toxic and carcinogenic contaminants commonly found in environmental samples, and efficient online detection of these contaminants is still challenging at the present stage. Here, we report an advanced Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) sensor for in-situ and simultaneous detection of multiple CHCs, including monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, trichloroethylene, perchloroethylene, and chloroform. The polycrystalline silver halide sensor fiber had a unique integrated planar-cylindric geometry, and was coated with an ethylene/propylene copolymer membrane to act as a solid phase extractor, which greatly amplified the analytical signal and contributed to a higher detection sensitivity compared to the previously reported sensors. This system exhibited a high detection sensitivity towards the CHCs mixture at a wide concentration range of 5~700 ppb. The FTIR-ATR sensor described in this study has a high potential to be utilized as a trace-sensitive on-line device for water contamination monitoring.

  8. Determination of protection zones for Dutch groundwater wells against virus contamination--uncertainty and sensitivity analysis.

    Science.gov (United States)

    Schijven, J F; Mülschlegel, J H C; Hassanizadeh, S M; Teunis, P F M; de Roda Husman, A M

    2006-09-01

    Protection zones of shallow unconfined aquifers in The Netherlands were calculated that allow protection against virus contamination to the level that the infection risk of 10(-4) per person per year is not exceeded with a 95% certainty. An uncertainty and a sensitivity analysis of the calculated protection zones were included. It was concluded that protection zones of 1 to 2 years travel time (206-418 m) are needed (6 to 12 times the currently applied travel time of 60 days). This will lead to enlargement of protection zones, encompassing 110 unconfined groundwater well systems that produce 3 x 10(8) m3 y(-1) of drinking water (38% of total Dutch production from groundwater). A smaller protection zone is possible if it can be shown that an aquifer has properties that lead to greater reduction of virus contamination, like more attachment. Deeper aquifers beneath aquitards of at least 2 years of vertical travel time are adequately protected because vertical flow in the aquitards is only 0.7 m per year. The most sensitive parameters are virus attachment and inactivation. The next most sensitive parameters are grain size of the sand, abstraction rate of groundwater, virus concentrations in raw sewage and consumption of unboiled drinking water. Research is recommended on additional protection by attachment and under unsaturated conditions.

  9. Determination of data correction coefficients and the sensitivities of the KIER air-borne gamma-ray spectrometer survey system

    International Nuclear Information System (INIS)

    Koo, J.H.; Cho, D.H.; Park, Y.S.

    1982-01-01

    In air-borne gamma-ray spectrometer survey, the observed data must be corrected for the background, Compton scattering and flight altitude. And the corrected data are usually converted into the radiometric elements equivalents of the ground, using the sensitivities of the survey system. Accordingly, the correction coefficients and the sensitivities are determined as follows for the KIER air-borne survey system. The stripping or Compton scattering coefficients α, β and γ at the ground level were first determined on the basis of the gamma-ray count rates due to the 5 concrete calibration pads of the Soosaek Airbase, together with the radiometric elements concentrations of the core samples taken from the pads. As for the determination of the exponential altitude coefficients anti μ(K), anti μ(U), anti μ(Th) and anti μ(Tc), the count rates observed over the Hongseong Test Strip of about 3 km length were used after they had been corrected for the background and Compton scattering. The background count rates mainly caused by the air-craft as well as cosmic radiations were determined with the data taken over the West Sea near Anmyon Island, Chung-cheongnam-do. And the corrected count rates observed over the Strip, combined with the average radiometric elements concentrations of the Strip, yielded the sensitivities k(K), k(U) and k(Th) at the 400 feet flight altitude. (author)

  10. Three-site sandwich radioimmunoassay with monoclonal antibodies for a sensitive determination of human alpha-fetoprotein

    International Nuclear Information System (INIS)

    Nomura, M.; Imai, M.; Takahashi, K.; Kumakura, T.; Tachibana, K.; Aoyagi, S.; Usuda, S.; Nakamura, T.; Miyakawa, Y.; Mayumi, M.

    1983-01-01

    Utilizing monoclonal antibodies against human alpha-fetoprotein, 3 distinct antigenic determinants were identified. These antigenic determinants, provisionally designated a, b and c, were arranged in such a manner that the binding of one determinant with the corresponding antibody did not inhibit, or only barely inhibited the binding of antibodies directed to the other 2 determinants. Monoclonal antibodies with 3 different specificities were, therefore, applied to develop a sandwich-type solid-phase radioimmunoassay of the antigen in which wells were coated with anti-a, and radiolabeled anti-b together with radiolabeled anti-c was employed to detect the bound antigen. The 3-site sandwich radioimmunoassay involving 3 different determinants gave a higher sensitivity than 2-site assays in which only anti-b or anti-c was employed as a radiolabeled reagent, because the radioactivity of the 2 labeled antibodies was added on the antigen bound to immobilized anti-a. (Auth.)

  11. Determination of the sensitivity of Tc-99-NMR-measurements with a 250 MHz-spectrometer

    International Nuclear Information System (INIS)

    Findeisen, M.; Lorenz, B.; Wahren, M.

    1990-01-01

    By means of different concentrations the signal-to-noise ratios of Tc-99-NMR spectra were determined applying well measurable Tc-samples [tetrabutylammonium pertechnetate, TBA (TcO 4 )] and a 250 MHz-spectrometer. The signal-to-noise ratios of the spectra were determined by using the integrated routines of the firm's software and accumulating different number of scans. By fittings of data of the signal-to-noise ratio dependence and by extrapolation the minimum Tc-concentration could be empirically found out. Applying a duration of measurements of 12 hours about 10 -7 molar concentrations can be determined. (orig.) [de

  12. New highly sensitive method of simultaneous instrumental neutron activation determination of 12 microelements in vine

    International Nuclear Information System (INIS)

    Shoniya, N.I.

    1977-01-01

    The main principles and methods of simultaneous multi-element instrumental neutron activation determination of microelements in vine seeds are presented. The methods permit to carry out quantitative evaluation for every single corn of the seeds. It is shown that the method of instrumental neutron activation analysis with the utilization of a semiconductor spectrometer of high resolution and mini electronic computer permit to carry out serial determinations of 12 microelements in the individual corns of vine seeds of different sorts. This method will permit to determine the missing or excess content of this or that biologically important microelement in soils, plants, fruit and genetic material - seeds, and so to determine the optimum conditions of growing plants by applying microelement fertilizers as extra nutrient means

  13. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    Science.gov (United States)

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Sensitivity and Selectivity on Aptamer-Based Assay: The Determination of Tetracycline Residue in Bovine Milk

    Directory of Open Access Journals (Sweden)

    Sohee Jeong

    2012-01-01

    Full Text Available A competitive enzyme-linked aptamer assay (ELAA to detect tetracycline in milk was performed by using two different aptamers individually; one is 76 mer-DNA aptamer and the other is 57 mer-RNA aptamer. The best optimum condition was obtained without monovalent ion, Na+ and also by adding no Mg2+ ion in the assay buffer, along with RT incubation. The optimized ELAA showed a good sensitivity (LOD of 2.10 × 10−8 M with a wide dynamic range (3.16 × 10−8 M ~ 3.16 × 10−4 M. In addition, the average R.S.D. across all data points of the curve was less than 2.5% with good recoveries (~101.8% from the milk media. Thus, this method provides a good tool to monitor tetracycline in milk from MRLs’ point of view. However, this ELAA method was not superior to the ELISA method in terms of specificity. This paper describes that it does not always give better sensitivity and specificity in assays even though aptamers have several advantages over antibodies and have been known to be good binders for binding assays.

  15. Fabrication of CuO nanoplatelets for highly sensitive enzyme-free determination of glucose

    Energy Technology Data Exchange (ETDEWEB)

    Wang Juan [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China); Zhang Weide, E-mail: zhangwd@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China)

    2011-09-01

    Highlights: > Adhered growth of CuO nanoplatelets on Cu foils. > Enzyme-free glucose sensor with very high sensitivity. > Excellent stability and good anti-interference ability. - Abstract: CuO nanoplatelets were grown on Cu foils by a one step, template free process. The structure and morphology of the CuO nanoplatelets were characterized by X-ray diffraction, scanning and transmission electron microscopy. The CuO nanoplatelets grown on Cu foil were integrated to be an electrode for glucose sensing. The electrocatalytic activity of the CuO nanoplatelets electrode for glucose in alkaline media was investigated by cyclic voltammetry and chronoamperometry. The electrode exhibits a sensitivity of 3490.7 {mu}A mM{sup -1} cm{sup -2} to glucose which is much higher than that of most reported enzyme-free glucose sensors and the linear range was obtained over a concentration up to 0.80 mM with a detection limit of 0.50 {mu}M (signal/noise = 3). Exhilaratingly, the electrode based on the CuO nanoplatelets is resistant against poisoning by chloride ion, and the interference from the oxidation of common interfering species, such as uric acid, ascorbic acid, dopamine and carbonhydrate compounds, can also be effectively avoided. Finally, the electrode was applied to analyze glucose concentration in human serum samples.

  16. Piezoelectric sensor for sensitive determination of metal ions based on the phosphate-modified dendrimer

    Science.gov (United States)

    Wang, S. H.; Shen, C. Y.; Lin, Y. M.; Du, J. C.

    2016-08-01

    Heavy metal ions arising from human activities are retained strongly in water; therefore public water supplies must be monitored regularly to ensure the timely detection of potential problems. A phosphate-modified dendrimer film was investigated on a quartz crystal microbalance (QCM) for sensing metal ions in water at room temperature in this study. The chemical structures and sensing properties were characterized by Fourier transform infrared spectroscopy and QCM measurement, respectively. This phosphate-modified dendrimer sensor can directly detect metal ions in aqueous solutions. This novel sensor was evaluated for its capacity to sense various metal ions. The sensor exhibited a higher sensitivity level and shorter response time to copper(II) ions than other sensors. The linear detection range of the prepared QCM based on the phosphate-modified dendrimer was 0.0001 ∼ 1 μM Cu(II) ions (R2 = 0.98). The detection properties, including sensitivity, response time, selectivity, reusability, maximum adsorption capacity, and adsorption equilibrium constants, were also investigated.

  17. Sensitive and direct determination of lithium by mixed-mode chromatography and charged aerosol detection.

    Science.gov (United States)

    Dai, Lulu; Wigman, Larry; Zhang, Kelly

    2015-08-21

    A sensitive analytical method using mixed mode HPLC separation coupled with charged aerosol detection (CAD) was developed for quantitative analysis of lithium. The method is capable of separating lithium ion from different drug matrices and other ions in a single run thus eliminating the organic matrix and ionic analyte interferences without extensive sample preparation such as derivatization and extraction. The separation space and chromatographic conditions are defined by systematic studies of the retention behaviors of lithium and potential interfering ions and different type of pharmaceutical APIs (active pharmaceutical ingredients) under reversed-phase, HILIC and cation/anion exchange mechanisms. Compared to other current analytical techniques for lithium analysis, the presented method provides a new approach and demonstrates high sensitivity (0.02ng for LOD and 0.08ng for LOQ in both standard and sample solution). The method has been validated for pharmaceutical samples and can be potentially applied to biological, food and environmental samples. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Sensitivity of DF-ICP-MS, PERALS and alpha-spectrometry for the determination of actinides. A comparison

    International Nuclear Information System (INIS)

    Ayranov, M.; Kraehenbuehl, U.

    2009-01-01

    We applied three techniques (DF-ICP-MS, PERALS and alpha-spectrometry) for the determination of minor actinides at environmental levels. For each method the limit of detection and the resolution were estimated in order to study the content and isotopic composition of the actinides. Two international reference materials, IAEA-135 (Irish Sea Sediment) and IAEA-300 (Baltic Sea sediment) were analyzed for activity concentrations of 238 Pu, 239 Pu, 240 Pu, 241 Pu and 241 Am. The sensitivities of the three determination techniques were compared. (author)

  19. Age-dependent effects of He-Ne laser irradiation on the membrane fluidity of human erythrocytes

    Science.gov (United States)

    Kovacs, Eugenia; Savopol, Tudor; Pologea-Moraru, Roxana; Makropoulou, Mersini I.; Serafetinides, Alexander A.

    1997-12-01

    The low power He-Ne laser radiation has been extensively used in past decades as medical device to relieve pain, accelerate wound healing as well as aiming beam in invisible laser beam in invisible laser beam applications. It is not known however if there are any secondary, undesirable effects of He-Ne laser radiation on the irradiated tissue. In this paper we investigate the changes induced in membrane fluidity of human erythrocyte during/upon the interaction with the He-Ne laser beam having the parameters currently used for target aiming in laser surgery.

  20. Sensitive radioimmunoassay for the determination of antibodies to mouse hepatitis virus

    Energy Technology Data Exchange (ETDEWEB)

    Leibowitz, J L [California Univ., San Diego, La Jolla (USA); Fung, L S; Levy, G A [Toronto Univ., Ontario (Canada)

    1983-05-01

    A solid-phase radioimmunoassay is described for the detection of antibodies to mouse hepatitis virus. Viruses were purified by velocity and isopycnic gradient centrifugation and 96-well plastic plates were coated with viral antigens. To allow the detection of most serotypes of low titered antisera, a pool of antigens from several viral serotypes were employed. The second antibody, an affinity-purified goat antimouse immunoglobulin, detects IgG, IgM and IgA antibodies. This assay is more sensitive than either the plaque reduction assay or the commercially available enzyme-linked immunosorbant assay and proved to be useful for screening mouse colonies for the presence of mouse hepatitis virus, following seroconversion in experimental animals and in the production of monoclonal antibodies to both structural and nonstructural proteins.

  1. A sensitive radioimmunoassay for the determination of antibodies to mouse hepatitis virus

    International Nuclear Information System (INIS)

    Leibowitz, J.L.; Fung, L.S.; Levy, G.A.

    1983-01-01

    A solid-phase radioimmunoassay is described for the detection of antibodies to mouse hepatitis virus. Viruses were purified by velocity and isopycnic gradient centrifugation and 96-well plastic plates were coated with viral antigens. To allow the detection of most serotypes of low titered antisera, a pool of antigens from several viral serotypes were employed. The second antibody, an affinity-purified goat antimouse immunoglobulin, detects IgG, IgM and IgA antibodies. This assay is more sensitive than either the plaque reduction assay or the commercially available enzyme-linked immunosorbant assay and proved to be useful for screening mouse colonies for the presence of mouse hepatitis virus, following seroconversion in experimental animals and in the production of monoclonal antibodies to both structural and nonstructural proteins. (Auth.)

  2. On determining dead layer and detector thicknesses for a position-sensitive silicon detector

    Science.gov (United States)

    Manfredi, J.; Lee, Jenny; Lynch, W. G.; Niu, C. Y.; Tsang, M. B.; Anderson, C.; Barney, J.; Brown, K. W.; Chajecki, Z.; Chan, K. P.; Chen, G.; Estee, J.; Li, Z.; Pruitt, C.; Rogers, A. M.; Sanetullaev, A.; Setiawan, H.; Showalter, R.; Tsang, C. Y.; Winkelbauer, J. R.; Xiao, Z.; Xu, Z.

    2018-04-01

    In this work, two particular properties of the position-sensitive, thick silicon detectors (known as the "E" detectors) in the High Resolution Array (HiRA) are investigated: the thickness of the dead layer on the front of the detector, and the overall thickness of the detector itself. The dead layer thickness for each E detector in HiRA is extracted using a measurement of alpha particles emitted from a 212Pb pin source placed close to the detector surface. This procedure also allows for energy calibrations of the E detectors, which are otherwise inaccessible for alpha source calibration as each one is sandwiched between two other detectors. The E detector thickness is obtained from a combination of elastically scattered protons and an energy-loss calculation method. Results from these analyses agree with values provided by the manufacturer.

  3. High-sensitivity determination of radioactive cesium in Japanese foodstuffs. 3 years after the Fukushima accident

    International Nuclear Information System (INIS)

    Katsumi Shozugawa; Mayumi Hori; Motoyuki Matsuo

    2016-01-01

    We analyzed 134 Cs, 137 Cs and 40 K in 96 foodstuffs in supermarkets with high sensitivity over 3 years after Fukushima accident. Milk, yoghurt, rice, tea, salmon, cereal, blueberry, miso, and apples had a trace of 134 Cs and 137 Cs from 10 -3 to 100 Bq/kg, however, some mushrooms that were bought in the outer Fukushima prefecture were contaminated by radioactive cesium over the regulatory limit (100 Bq/kg). In view of the 134 Cs/ 137 Cs radioactivity ratio, we can conclude that 137 Cs detected in remote areas 300 km or more from Fukushima Nuclear power plant contained activity from Pre-Fukushima events such as Chernobyl accident (1986) and atmospheric nuclear explosions (from 1945). (author)

  4. Sensitive method for the determination of different S(IV) species in cloud and fog water.

    Science.gov (United States)

    Lammel, G

    1996-08-01

    Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and fog water in the range 0.012-2.4 mg S(IV)-S/L. The samples have been preserved prior to storage and S(IV) species have been determined as hydroxy methanesulfonate (HMS) together with the low molecular weight carboxylic acid anions, formate and acetate. Samples have been divided and treated differently such that total S(IV) as well as the non-oxidizable fraction of S(IV) (as given by the reactivity with H(2)O(2), added in surplus) could be determined. The difference between the two corresponds to the S(IV) fraction subjected to oxididation, which is of paramount interest in cloud and fogwater chemistry.

  5. High-level iron mitigates fusaricidin-induced membrane damage and reduces membrane fluidity leading to enhanced drug resistance in Bacillus subtilis.

    Science.gov (United States)

    Yu, Wen-Bang; Ye, Bang-Ce

    2016-05-01

    Fusaricidins are a class of cyclic lipopeptide antibiotics that have strong antifungal activities against plant pathogenic fungi and excellent bactericidal activities against Gram-positive bacteria. The mechanism through which fusaricidin exerts its action is not yet entirely clear. To investigate the mode of action of fusaricidin, we determined the physiological and transcriptional responses of Bacillus subtilis to fusaricidin treatment by using a systems-level approach. Our data show that fusaricidin rapidly induced the expression of σ(W) regulon and caused membrane damage in B. subtilis. We further demonstrated that ferric ions play multiple roles in the action of fusaricidin on B. subtilis. Iron deprivation blocked the formation of hydroxyl radical in the cells and significantly inhibited the bactericidal activity of fusaricidin. Conversely, high levels of iron (>2 mM) repressed the expression of BkdR regulon, resulting in a smaller cellular pool of branched-chain precursors for iso- and anteiso-branched fatty acids, which in turn led to a decrease in the proportion of branched-chain fatty acids in the membrane of B. subtilis. This change in membrane composition reduced its bilayer fluidity and increased its resistance to antimicrobial agents. In conclusion, our experiments uncovered some novel interactions and a synergism between cellular iron levels and drug resistance in Gram-positive bacteria. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Sensitive determination of iodide in the presence of large quantities of chloride

    International Nuclear Information System (INIS)

    Hainberger, L.; Lenzi, E.

    1982-01-01

    A determination of iodide with catalytic oxidation of p-phenetidine is described. A dye is formed with a maximum of absorption at 490 nm. The law of Lambert-Beer is obeyed between 0.6 and 2.2 ppm. Some of the interferents are examined. (Author)

  7. A note on determination of the diffuse-field sensitivity of microphones using the reciprocity technique

    DEFF Research Database (Denmark)

    Barrera Figueroa, Salvador; Jacobsen, Finn

    2008-01-01

    angles of incidence but also on the accuracy of the frequency response at normal incidence. By contrast, this paper is concerned with determining the absolute diffuse-field response of a microphone using the reciprocity technique. To examine this possibility, a reciprocity calibration setup is used...

  8. Sensitive determination of dopamine levels via surface-enhanced Raman scattering of Ag nanoparticle dimers.

    Science.gov (United States)

    Yu, Xiantong; He, XiaoXiao; Yang, Taiqun; Zhao, Litao; Chen, Qichen; Zhang, Sanjun; Chen, Jinquan; Xu, Jianhua

    2018-01-01

    Dopamine (DA) is an important neurotransmitter in the hypothalamus and pituitary gland, which can produce a direct influence on mammals' emotions in midbrain. Additionally, the level of DA is highly related with some important neurologic diseases such as schizophrenia, Parkinson, and Huntington's diseases, etc. In light of the important roles that DA plays in the disease modulation, it is of considerable significance to develop a sensitive and reproducible approach for monitoring DA. The objective of this study was to develop an efficient approach to quantitatively monitor the level of DA using Ag nanoparticle (NP) dimers and enhanced Raman spectroscopy. Ag NP dimers were synthesized for the sensitive detection of DA via surface-enhanced Raman scattering (SERS). Citrate was used as both the capping agent of NPs and sensing agent to DA, which is self-assembled on the surface of Ag NP dimers by reacting with the surface carboxyl group to form a stable amide bond. To improve accuracy and precision, the multiplicative effects model for surface-enhanced Raman spectroscopy was utilized to analyze the SERS assays. A low limits of detection (LOD) of 20 pM and a wide linear response range from 30 pM to 300 nM were obtained for DA quantitative detection. The SERS enhancement factor was theoretically valued at approximately 10 7 by discrete dipole approximation. DA was self-assembled on the citrate capped surface of Ag NPs dimers through the amide bond. The adsorption energy was estimated to be 256 KJ/mol using the Langmuir isotherm model. The density functional theory was used to simulate the spectral characteristics of SERS during the adsorption of DA on the surface of the Ag dimers. Furthermore, to improve the accuracy and precision of quantitative analysis of SERS assays with a multiplicative effects model for surface-enhanced Raman spectroscopy. A LOD of 20 pM DA-level was obtained, and the linear response ranged from 30 pM to 300 nM for quantitative DA detection. The

  9. Determining the Sensitivity of the Hf-Nd Proxy to Glacial Weathering

    Science.gov (United States)

    Namsinh, A.; Scher, H.; Piotrowski, A. M.

    2017-12-01

    The history of polar ice sheets through the Cenozoic is incompletely known. Estimates of the onset of northern hemisphere glaciation range from the Pliocene to mid-Eocene and precursor Antarctic glaciations are believed to have commenced in the middle Eocene. Uncertainty surrounding the history of ice sheets has resulted in debates about the sensitivity of ice sheets to changes in atmospheric CO2 through the Cenozoic. Geochemical proxies for continental weathering — particularly those that are sensitive to mechanical breakdown of the upper continental crust by ice sheets — could improve the fidelity of paleoclimate reconstructions of ice sheet history. Coupled hafnium (Hf) and neodymium (Nd) isotopes in seawater and authigenic sediment phases show a strong correlation with mechanical weathering rates, however the proxy has not been systematically tested on Pleistocene time scales. We measured the Hf and Nd isotope ratios of authigenic and detrital phases of sediment cores from 1150 m to 4045 m depth on the Rockall Plateau in the NE Atlantic Ocean. Our study is limited to the LGM, deglaciation and Holocene intervals. The authigenic fraction was extracted from bulk sediments by leaching with dilute hydroxylamine hydrochloride and EDTA to prevent readsorption of Hf. A stronger leach solution was then used to isolate the terrigenous detrital fraction. The fidelity of the seawater signal obtained by leaching is assessed by comparison of leachate eNd values to previously published eNd values from uncleaned forams from the same depth intervals. Initial tests with Holocene and deglacial samples verify that leachate eNd values are statistically indistinguishable from uncleaned forams. Shale-normalized REE patterns for leachates reveal negative Ce anomalies and a MREE enrichment typical of Fe-Mn oxydydroxide phases. Coupled Hf-Nd isotopes from authigenic leachates from our initial tests fall along the Seawater Array when plotted on a Hf-Nd isotope diagram, confirming

  10. Sensitive spectrophotometric determination of aceclofenac following azo dye formation with 4-carboxyl-2,6-dinitrobenzene diazonium ion.

    Science.gov (United States)

    Aderibigbe, Segun A; Adegoke, Olajire A; Idowu, Olakunle S; Olaleye, Sefiu O

    2012-01-01

    The study is a description of a sensitive spectrophotometric determination of aceclofenac following azo dye formation with 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD). Spot test and thin layer chromatography revealed the formation of a new compound distinct from CDNBD and aceclofenac. Optimization studies established a reaction time of 5 min at 30 degrees C after vortex mixing the drug/CDNBD for 10 s. An absorption maximum of 430 nm was selected as analytical wavelength. A linear response was observed over 1.2-4.8 μg/mL of aceclofenac with a correlation coefficient of 0.9983 and the drug combined with CDNBD at stoichiometric ratio of 2 : 1. The method has a limit of detection of 0.403 μg/mL, limit of quantitation of 1.22 μg/mL and is reproducible over a three day assessment. The method gave Sandell's sensitivity of 3.279 ng/cm2. Intra- and inter-day accuracies (in terms of errors) were less than 6% while precisions were of the order of 0.03-1.89% (RSD). The developed spectrophotometric method is of equivalent accuracy (p > 0.05) with British Pharmacopoeia, 2010 potentiometric method. It has the advantages of speed, simplicity, sensitivity and more affordable instrumentation and could found application as a rapid and sensitive analytical method of aceclofenac. It is the first described method by azo dye derivatization for the analysis of aceclofenac in bulk samples and dosage forms.

  11. Determination of photosynthetic and enzymatic biomarkers sensitivity used to evaluate toxic effects of copper and fludioxonil in alga Scenedesmus obliquus

    International Nuclear Information System (INIS)

    Dewez, David; Geoffroy, Laure; Vernet, Guy; Popovic, Radovan

    2005-01-01

    Modulated PAM fluorometry and Plant Efficiency Analyser methods were used to investigate photosynthetic fluorescence parameters of alga Scenedesmus obliquus exposed to inhibitory effect of fungicides copper sulphate and fludioxonil (N-(4-nitrophenyl)-N'-propyl-uree). The change of those parameters were studied when alga S. obliquus have been exposed during 48 h to different concentrations of fungicides (1, 2 and 3 mg l -1 ). Under the same condition, enzymatic activities of catalase, ascorbate peroxidase, glutathione reductase and glutathione S-transferase were investigated to evaluate antioxidative response to fungicides effects. The change of sensitivity of those parameters was dependent to the mode of fungicide action, their concentration and time of exposure. For copper effects, the most indicative photosynthetic biomarkers were parameters Q N as non-photochemical fluorescence quenching, Q Emax as the proton induced fluorescence quenching and ABS/RC as the antenna size per photosystem II reaction center. Copper induced oxidative stress was indicated by increased activity of catalase serving as the most sensitive and valuable enzymatic biomarker. On the other hand, fludioxonil effect on photosynthetic parameters was very negligible and consequently not very useful as biomarkers. However, fludioxonil induced strong antioxidative activities associated with cytosol enzymes, as we found for catalase, ascorbate peroxidase and glutathione S-transferase activities. By obtained results, we may suggest for the activation of those enzymes to be sensitive and valuable biomarkers of oxidative stress induced by fludioxonil. Determination of biomarkers sensitivity may offer advantages in providing real criteria to use them for ecotoxicological diagnostic studies

  12. A Highly Sensitive Multicommuted Flow Analysis Procedure for Photometric Determination of Molybdenum in Plant Materials without a Solvent Extraction Step

    Directory of Open Access Journals (Sweden)

    Felisberto G. Santos

    2017-01-01

    Full Text Available A highly sensitive analytical procedure for photometric determination of molybdenum in plant materials was developed and validated. This procedure is based on the reaction of Mo(V with thiocyanate ions (SCN− in acidic medium to form a compound that can be monitored at 474 nm and was implemented employing a multicommuted flow analysis setup. Photometric detection was performed using an LED-based photometer coupled to a flow cell with a long optical path length (200 mm to achieve high sensitivity, allowing Mo(V determination at a level of μg L−1 without the use of an organic solvent extraction step. After optimization of operational conditions, samples of digested plant materials were analyzed employing the proposed procedure. The accuracy was assessed by comparing the obtained results with those of a reference method, with an agreement observed at 95% confidence level. In addition, a detection limit of 9.1 μg L−1, a linear response (r=0.9969 over the concentration range of 50–500 μg L−1, generation of only 3.75 mL of waste per determination, and a sampling rate of 51 determinations per hour were achieved.

  13. Sensitive determination of buformin using poly-aminobenzoic acid modified glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    Gui-Ying Jin

    2012-12-01

    Full Text Available Glassy carbon electrode, which is used to electrochemically determine the content of buformin, is modified with an electropolymerized film of p-aminobenzoic acid in pH 7.0 acetate buffer solution (ABS. The polymer showed an excellent electrocatalytic activity for the reduction of buformin. In pH 7.0 ABS, the cathodic peak current increased linearly over three concentration intervals of buformin, and the detection limit (S/N=3 was 2.0×10−9 g/mL. The method was successfully applied to directly determine buformin in tablets with standard addition recoveries of 95.8–102.5%. The proposed method is simple, cheap and highly efficient. Keywords: Chemically modified electrode, Aminobenzoic acid, Buformin

  14. Rapid and Sensitive Determination of Lipid Oxidation Using the Reagent Kit Based on Spectrophotometry (FOODLABfat System

    Directory of Open Access Journals (Sweden)

    Chang Woo Kwon

    2016-01-01

    Full Text Available The reliability and availability of FOODLABfat system for determining acid value (AV and peroxide value (POV were assessed during the hydrolytic rancidification and lipid oxidation of edible oils. This reagent kit based on spectrophotometry was compared to the official methods (ISO 660 and 3960 protocols based on manual titration employing the standard mixture for the simulated oxidation models and edible oils during the thermally induced oxidation at 180°C. The linear regression line of standard mixture and the significant difference of thermally oxidized time course study determined between them showed high correlations (R2=0.998 and p<0.05 in both AVs and POVs. Considering ISO protocols with a probability of human error in manual titration, the rapidness and simplicity of the reagent kit based on spectrophotometry make it a promising alternative to monitor the lipid oxidation of edible oils and lipid-containing foods.

  15. Compact reversed-field pinch reactors (CRFPR): sensitivity study and design-point determination

    International Nuclear Information System (INIS)

    Hagenson, R.L.; Krakowski, R.A.

    1982-07-01

    If the costing assumptions upon which the positive assessment of conventional large superconducting fusion reactors are based proves overly optimistic, approaches that promise considerably increased system power density and reduced mass utilization will be required. These more compact reactor embodiments generally must operate with reduced shield thickness and resistive magnets. Because of the unique, magnetic topology associated with the Reversed-Field Pinch (RFP), the compact reactor embodiment for this approach is particularly attractive from the viewpoint of low-field resistive coils operating with Ohmic losses that can be made small relative to the fusion power. A comprehensive system model is developed and described for a steady-state, compact RFP reactor (CRFPR). This model is used to select a unique cost-optimized design point that will be used for a conceptual engineering design. The cost-optimized CRFPR design presented herein would operate with system power densities and mass utilizations that are comparable to fission power plants and are an order of magnitude more favorable than the conventional approaches to magnetic fusion power. The sensitivity of the base-case design point to changes in plasma transport, profiles, beta, blanket thickness, normal vs superconducting coils, and fuel cycle (DT vs DD) is examined. The RFP approach is found to yield a point design for a high-power-density reactor that is surprisingly resilient to changes in key, but relatively unknown, physics and systems parameters

  16. Multiple myeloma cells’ capacity to decompose H2O2 determines lenalidomide sensitivity

    Science.gov (United States)

    Sebastian, Sinto; Zhu, Yuan X.; Braggio, Esteban; Shi, Chang-Xin; Panchabhai, Sonali C.; Van Wier, Scott A.; Ahmann, Greg J.; Chesi, Marta; Bergsagel, P. Leif; Stewart, A. Keith

    2017-01-01

    Lenalidomide is an immunomodulatory drug (IMiDs) with clinical efficacy in multiple myeloma (MM) and other late B-cell neoplasms. Although cereblon (CRBN) is an essential requirement for IMiD action, the complete molecular and biochemical mechanisms responsible for lenalidomide-mediated sensitivity or resistance remain unknown. Here, we report that IMiDs work primarily via inhibition of peroxidase-mediated intracellular H2O2 decomposition in MM cells. MM cells with lower H2O2-decomposition capacity were more vulnerable to lenalidomide-induced H2O2 accumulation and associated cytotoxicity. CRBN-dependent degradation of IKZF1 and IKZF3 was a consequence of H2O2-mediated oxidative stress. Lenalidomide increased intracellular H2O2 levels by inhibiting thioredoxin reductase (TrxR) in cells expressing CRBN, causing accumulation of immunoglobulin light-chain dimers, significantly increasing endoplasmic reticulum stress and inducing cytotoxicity by activation of BH3-only protein Bim in MM. Other direct inhibitors of TrxR and thioredoxin (Trx) caused similar cytotoxicity, but in a CRBN-independent fashion. Our findings could help identify patients most likely to benefit from IMiDs and suggest direct TrxR or Trx inhibitors for MM therapy. PMID:28028022

  17. Quantitative enzyme activity determination with zeptomole sensitivity by microfluidic gradient-gel zymography.

    Science.gov (United States)

    Hughes, Alex J; Herr, Amy E

    2010-05-01

    We describe a sensitive zymography technique that utilizes an automated microfluidic platform to report enzyme molecular weight, amount, and activity (including k(cat) and K(m)) from dilute protein mixtures. Calf intestinal alkaline phosphatase (CIP) is examined in detail as a model enzyme system, and the method is also demonstrated for horseradish peroxidase (HRP). The 40 min assay has a detection limit of 5 zmol ( approximately 3 000 molecules) of CIP. Two-step pore-limit electrophoresis with enzyme assay (PLENZ) is conducted in a single, straight microchannel housing a polyacrylamide (PA) pore-size gradient gel. In the first step, pore limit electrophoresis (PLE) sizes and pseudoimmobilizes resolved proteins. In the second step, electrophoresis transports both charged and neutral substrates into the PLE channel to the entrapped proteins. Arrival of substrate at the resolved enzyme band generates fluorescent product that reveals enzyme molecular weight against a fluorescent protein ladder. Additionally, the PLENZ zymography assay reports the kinetic properties of CIP in a fully quantitative manner. In contrast to covalent enzyme immobilization, physical pseudoimmobilization of CIP in the PA gel does not significantly reduce its maximum substrate turnover rate. However, an 11-fold increase in the Michaelis constant (over the free solution value) is observed, consistent with diffusional limitations on substrate access to the enzyme active site. PLENZ offers a robust platform for rapid and multiplexed functional analysis of heterogeneous protein samples in drug discovery, clinical diagnostics, and biocatalyst engineering.

  18. Highly sensitive electrochemical determination of Sunset Yellow based on gold nanoparticles/graphene electrode

    International Nuclear Information System (INIS)

    Wang, Jin; Yang, Beibei; Wang, Huiwen; Yang, Ping; Du, Yukou

    2015-01-01

    An electrochemical sensor was prepared using Au nanoparticles and reduced graphene successfully decorated on the glassy carbon electrode (Au/RGO/GCE) through an electrochemical method which was applied to detect Sunset Yellow (SY). The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical measurements. The results of cyclic voltammetry (CV) proved that Au/RGO/GCE had the highest catalytic activity for the oxidation of SY as compared with GCE, Au/GCE, and RGO/GCE. Differential pulse voltammetry (DPV) showed that the linear calibration curves for SY on Au/RGO/GCE in the range of 0.002 μM–109.14 μM, and the detection limit was estimated to be 2 nM (S/N = 3). These results suggested that the obtained Au/RGO/GCE was applied to detect SY with high sensitivity, low detection limit and good stability, which provided a promising future for the development of portable sensor in food additives. - Highlights: • An Au/RGO composite was fabricated by electrochemical deposition method. • The oxidation current of SY on the composition is up to 10 μA. • The detection range of SY is 0.002–109.14 μM with a detection limit of 2 nM.

  19. Sensitive luminescent determination of DNA using the terbium(III)-difloxacin complex

    International Nuclear Information System (INIS)

    Yegorova, Alla V.; Scripinets, Yulia V.; Duerkop, Axel; Karasyov, Alexander A.; Antonovich, Valery P.; Wolfbeis, Otto S.

    2007-01-01

    The interaction of the terbium-difloxacin complex (Tb-DFX) with DNA has been examined by using UV-vis absorption and luminescence spectroscopy. The Tb-DFX complex shows an up to 85-fold enhancement of luminescence intensity upon titration with DNA. The long decay times allow additional detection schemes like time-resolved measurements in microplate readers to enhance sensitivity by off-gating short-lived background luminescence. Optimal conditions are found at equimolar concentrations of Tb 3+ and DFX (0.1 or 1 μM) at pH 7.4. Under these conditions, the luminescence intensity is linearly dependent on the concentration of ds-DNAs and ss-DNA between 1-1500 ng mL -1 and 4.5-270 ng mL -1 , respectively. The detection limit is 0.5 ng mL -1 for ds-DNAs and 2 ng mL -1 for ss-DNA. The mechanism for the luminescence enhancement was also studied

  20. Gonadotropin determination in 24-h-urine by sensitive LH and FSH radioimmunoassays

    International Nuclear Information System (INIS)

    Raid, A.; Fenske, M.; Koenig, A.

    1979-01-01

    Urinary lutropin (LH) and follitropin (FSH) were precipitated with acetone and measured by specific radioimmunoassays. Recovery experiments with special regard to urinary pH values were done by adding 125 I-labelled LH and FSH to unprocessed urine. At pH 4.5 68.6% of LH and 66.1% of FSH were recovered. Increasing pH values up to 6.0 resulted in a significant recovery loss of 125 I-LH, but not of 125 I-FSH. Immunoreactive FSH concentrations decreased significantly 6 and 48 hours after starting storage at room temperature. In healthy males and females there were found mean LH and FSH concentrations in 24-h-urine which were similar to those reported by others: LH: males: 22.6 IU; cycling females: 17.8 IU; postmenopausal females: 49.1 IU; FSH: males 6.0 IU; cycling females: 15.0 IU; postmenopausal females: 48.5 IU. Because of their high sensitivity and practicability. These radioimmunoassays could be clinically useful approaches in assessment of pituitary and gonadal disorders in human subjects. (author)

  1. Electrochemical aptasensor for highly sensitive determination of cocaine using a supramolecular aptamer and rolling circle amplification

    International Nuclear Information System (INIS)

    Shen, Bo; Yan, Yurong; Tang, Renkuan; Li, Yongguo; Li, Jianbo; Cheng, Wei; Ju, Huangxian; Ding, Shijia

    2015-01-01

    We report on a novel strategy for the electrochemical detection of cocaine. It is based on the use of a supramolecular aptamer, rolling circle amplification (RCA), and multiplex binding of a biotin-strepavidin system. The aptamer fragments were assembled to a supramolecular aptamer which, in the presence of cocaine, conjugates to streptavidin for anchoring of biotinylated circular DNA. This initiates RCA and enables sensitive electrochemical-enzymatic readout. A significant signal amplification was obtained by using streptavidin linked to alkaline phosphatase that binds to the remaining biotinylated detection probes and catalyzes the hydrolysis of the synthetic enzyme substrate α-naphthylphosphate. This dual amplification strategy tremendously increases the detection limit of the aptasensor. Under optimal conditions and using differential pulse voltammetry, cocaine can be detected in the concentration range between 2 and 500 nM with a detection limit as low as 1.3 nM (at S/N = 3). The method is specific and acceptably reproducible. It was successfully applied to the detection of cocaine in (spiked) urine samples. The data were in good agreement with those obtained by the GC-MS reference method. (author)

  2. Development of a sensitive passive sampler using indigotrisulfonate for the determination of tropospheric ozone.

    Science.gov (United States)

    Garcia, Gabriel; Allen, Andrew George; Cardoso, Arnaldo Alves

    2010-06-01

    A new sampling and analytical design for measurement of ambient ozone is presented. The procedure is based on ozone absorption and decoloration (at 600 nm) of indigotrisulfonate dye, where ozone adds itself across the carbon-carbon double bond of the indigo. A mean relative standard deviation of 8.6% was obtained using samplers exposed in triplicate, and a correlation coefficient (r) of 0.957 was achieved in parallel measurements using the samplers and a commercial UV ozone instrument. The devices were evaluated in a measurement campaign, mapping spatial and temporal trends of ozone concentrations in a region of southeast Brazil strongly influenced by seasonal agricultural biomass burning, with associated emissions of ozone precursors. Ozone concentrations were highest in rural areas and lowest at an urban site, due to formation during downwind transport and short-term depletion due to titration with nitric oxide. Ozone concentrations showed strong seasonal trends, due to the influences of precursor emissions, relative humidity and solar radiation intensity. Advantages of the technique include ease and speed of use, the ready availability of components, and excellent sensitivity. Achievable temporal resolution of ozone concentrations is 8 hours at an ambient ozone concentration of 3.8 ppb, or 2 hours at a concentration of 15.2 ppb.

  3. The mouse beam walking assay offers improved sensitivity over the mouse rotarod in determining motor coordination deficits induced by benzodiazepines.

    Science.gov (United States)

    Stanley, Joanna L; Lincoln, Rachael J; Brown, Terry A; McDonald, Louise M; Dawson, Gerard R; Reynolds, David S

    2005-05-01

    The mouse rotarod test of motor coordination/sedation is commonly used to predict clinical sedation caused by novel drugs. However, past experience suggests that it lacks the desired degree of sensitivity to be predictive of effects in humans. For example, the benzodiazepine, bretazenil, showed little impairment of mouse rotarod performance, but marked sedation in humans. The aim of the present study was to assess whether the mouse beam walking assay demonstrates: (i) an increased sensitivity over the rotarod and (ii) an increased ability to predict clinically sedative doses of benzodiazepines. The study compared the effects of the full benzodiazepine agonists, diazepam and lorazepam, and the partial agonist, bretazenil, on the mouse rotarod and beam walking assays. Diazepam and lorazepam significantly impaired rotarod performance, although relatively high GABA-A receptor occupancy was required (72% and 93%, respectively), whereas beam walking performance was significantly affected at approximately 30% receptor occupancy. Bretazenil produced significant deficits at 90% and 53% receptor occupancy on the rotarod and beam walking assays, respectively. The results suggest that the mouse beam walking assay is a more sensitive tool for determining benzodiazepine-induced motor coordination deficits than the rotarod. Furthermore, the GABA-A receptor occupancy values at which significant deficits were determined in the beam walking assay are comparable with those observed in clinical positron emission tomography studies using sedative doses of benzodiazepines. These data suggest that the beam walking assay may be able to more accurately predict the clinically sedative doses of novel benzodiazepine-like drugs.

  4. Iron oxyhydroxide nanorods with high electrochemical reactivity as a sensitive and rapid determination platform for 4-chlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuanyuan [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Britton Chance Center for Biomedical Photonics at Wuhan, National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Cheng, Qin; Zheng, Meng [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Xin [Britton Chance Center for Biomedical Photonics at Wuhan, National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-04-15

    Highlights: • Prepared FeOOH nanorods exhibited high reactivity toward the oxidation of 4-CP. • Response signals and detection sensitivity of 4-CP increased greatly by FeOOH. • Highly-sensitive and rapid determination platform was developed for 4-CP. • Practical application in water samples was studied, and the accuracy was good. - Abstract: Iron oxyhydroxide (FeOOH) nanorods were prepared through solvothermal reaction, and characterized using Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and scanning electron microscopy. Thereafter, the prepared FeOOH nanorods were used as sensing material to construct a novel detection platform for 4-chlorophenol (4-CP). The electrochemical behaviors of 4-CP were studied, and the oxidation peak currents increased greatly on the surface of FeOOH nanorods. The signal enhancement mechanism was studied for 4-CP, and it was found that the prepared FeOOH nanorods remarkably improved the electron transfer ability and surface adsorption efficiency of 4-CP. The influences of pH value, amount of FeOOH nanorods and accumulation time were examined. As a result, a highly-sensitive electrochemical method was developed for the rapid determination of 4-CP. The linear range was from 10 to 500 nM, and the detection limit was 3.2 nM. It was used in different water samples, and the results consisted with the values that obtained by high-performance liquid chromatography.

  5. Hepcidin as a possible marker in determination of malignancy degree and sensitivity of breast cancer cells to cytostatic drugs.

    Science.gov (United States)

    Yalovenko, T M; Todor, I M; Lukianova, N Y; Chekhun, V F

    2016-06-01

    To investigate the role of hepcidin (Hepc) in the formation of cells malignant phenotype in vitro and its expression in the dyna-mics of growth of Walker-256 carcinosarcoma with different sensitivity to doxorubicin (Dox). The cell lines used in the analysis included T47D, MCF-7, MDA-MB-231, MDA-MB-468, MCF/CP, and MCF/Dox. Hepc expression was studied by immunocytochemical method. "Free" iron content was determined by EPR spectroscopy. Determination of Hepc expression in homogenates of tumor tissue and in blood serum of rats with Dox-sensitive and -resistant Walker-256 carcinosarcoma was performed. It was found that Hepc levels in breast cancer (BC) cells with high degree of malignancy (MDA-MB-231, MDA-MB-468) and drug-resistant phenotype (MCF/CP, MCF/Dox) were by 1.5-2 times higher (p < 0.05) in comparison with sensitive and less malignant BC cells. The development of drug-resistant phenotype in Walker-256 carcinosarcoma cells was accompanied by increasing of Hepc and "free" iron content (by 2.4 and 1.2 times, respectively). The data of in vitro and in vivo research evidenced on involvement of Hepc in formation of BC cells malignant phenotype and their resistance to Dox.

  6. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

    Science.gov (United States)

    Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. Copyright © 2016. Published by Elsevier B.V.

  7. Determinants of attenuation and temperature sensitivity in the type 1 poliovirus Sabin vaccine.

    OpenAIRE

    Bouchard, M J; Lam, D H; Racaniello, V R

    1995-01-01

    To identify determinants of attenuation in the poliovirus type 1 Sabin vaccine strain, a series of recombinant viruses were constructed by using infectious cDNA clones of the virulent type 1 poliovirus P1/Mahoney and the attenuated type 1 vaccine strain P1/Sabin. Intracerebral inoculation of these viruses into transgenic mice which express the human receptor for poliovirus identified regions of the genome that conferred reduced neurovirulence. Exchange of smaller restriction fragments and sit...

  8. Speciation of Candida using chromogenic and cornmeal agar with determination of fluconazole sensitivity

    OpenAIRE

    Saroj Golia; K. Mallika Reddy; K. Sujatha Karjigi; Vivek Hittinahalli

    2013-01-01

    Objective and background: Candidiasis is an important cause of fungal infections. This study was carried out to determine the species incidence using chrom agar & cornmeal agar, susceptibility pattern to fluconazole by microbroth dilution methods of yeasts isolated from the clinical samples. Method: Positive samples for candidiasis where collected from 112 patients at Dr B R AMC from April 2010 to April 2011, processed by routine methods, chrom agar media and corn meal agar was used to spec...

  9. Effect of Growth Medium pH of Aeropyrum pernix on Structural Properties and Fluidity of Archaeosomes

    Directory of Open Access Journals (Sweden)

    Ajda Ota

    2012-01-01

    Full Text Available The influence of pH (6.0; 7.0; 8.0 of the growth medium of Aeropyrum pernix K1 on the structural organization and fluidity of archaeosomes prepared from a polar-lipid methanol fraction (PLMF was investigated using fluorescence anisotropy and electron paramagnetic resonance (EPR spectroscopy. Fluorescence anisotropy of the lipophilic fluorofore 1,6-diphenyl-1,3,5-hexatriene and empirical correlation time of the spin probe methylester of 5-doxylpalmitate revealed gradual changes with increasing temperature for the pH. A similar effect has been observed by using the trimethylammonium-6-diphenyl-1,3,5-hexatriene, although the temperature changes were much smaller. As the fluorescence steady-state anisotropy and the empirical correlation time obtained directly from the EPR spectra alone did not provide detailed structural information, the EPR spectra were analysed by computer simulation. This analysis showed that the archaeosome membranes are heterogeneous and composed of several regions with different modes of spin-probe motion at temperatures below 70°C. At higher temperatures, these membranes become more homogeneous and can be described by only one spectral component. Both methods indicate that the pH of the growth medium of A. pernix does not significantly influence its average membrane fluidity. These results are in accordance with TLC analysis of isolated lipids, which show no significant differences between PLMF isolated from A. pernix grown in medium with different pH.

  10. Sensitive spectrophotometric determination of ascorbic acid in drugs and foods using surface plasmon resonance band of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Kobra Zarei

    2015-12-01

    Full Text Available A simple and sensitive procedure was proposed for spectrophotometric determination of ascorbic acid. It was found that the reduction of Ag+ to silver nanoparticles (Ag-NPs by ascorbic acid in the presence of polyvinylpyrrolidone (PVP as a stabilizing agent produce very intense surface plasmon resonance peak of Ag-NPs. The plasmon absorbance of the Ag-NPs at λ = 440 nm allows the quantitative spectrophotometric detection of the ascorbic acid. The calibration curve was linear with concentration of ascorbic acid in the range of 0.5–60 μM. The detection limit was obtained as 0.08 μM. The influence of potential interfering substances on the determination of ascorbic acid was studied. The proposed method was successfully applied for the determination of ascorbic acid in some powdered drink mixtures, commercial orange juice, natural orange juice, vitamin C injection, effervescent tablet, and multivitamin tablet.

  11. Sensitive method for the quantitative determination of bromocriptine in human plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Salvador, Arnaud; Dubreuil, Didier; Denouel, Jannick; Millerioux, L

    2005-06-25

    A sensitive LC-MS-MS assay for the quantitative determination of bromocriptine has been developed and validated and is described in this work. The assay involved the extraction of the analyte from 1 ml of human plasma using a solid phase extraction on Oasis MCX cartridges. Chromatography was performed on a Symmetry C18 (2.1 mm x 100 mm, 3.5 microm) column using a mobile phase consisting of 25:75:01 acetonitrile-water-formic acid with a flow rate of 250 microl/min. The linearity was within the concentration range of 2-500 pg/ml. The lower limit of quantification was 2 pg/ml. This method has been demonstrated to be an improvement over existing methods due to its greater sensitivity and specificity.

  12. Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

    Science.gov (United States)

    Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2007-10-15

    The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.

  13. A new sensitive method of dissociation constants determination based on the isohydric solutions principle.

    Science.gov (United States)

    Michałowski, Tadeusz; Pilarski, Bogusław; Asuero, Agustin G; Dobkowska, Agnieszka

    2010-10-15

    The paper provides a new formulation and analytical proposals based on the isohydric solutions concept. It is particularly stated that a mixture formed, according to titrimetric mode, from a weak acid (HX, C(0)mol/L) and a strong acid (HB, Cmol/L) solutions, assumes constant pH, independently on the volumes of the solutions mixed, provided that the relation C(0)=C+C(2)·10(pK(1)) is valid, where pK(1)=-log K(1), K(1) the dissociation constant for HX. The generalized formulation, referred to the isohydric solutions thus obtained, was extended also to more complex acid-base systems. Particularly in the (HX, HB) system, the titration occurs at constant ionic strength (I) value, not resulting from presence of a basal electrolyte. This very advantageous conjunction of the properties provides, among others, a new, very sensitive method for verification of pK(1) value. The new method is particularly useful for weak acids HX characterized by low pK(1) values. The method was tested experimentally on four acid-base systems (HX, HB), in aqueous and mixed-solvent media and compared with the literature data. Some useful (linear and hyperbolic) correlations were stated and applied for validation of pK(1) values. Finally, some practical applications of analytical interest of the isohydricity (pH constancy) principle as one formulated in this paper were enumerated, proving the usefulness of such a property which has its remote roots in the Arrhenius concept. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Pulsed amperometric detection at glassy carbon electrodes: A new waveform for sensitive and reproducible determination of electroactive compounds.

    Science.gov (United States)

    Nardiello, Donatella; Palermo, Carmen; Natale, Anna; Quinto, Maurizio; Centonze, Diego

    2015-09-24

    In this work, the application of a new pulsed amperometric detection (PAD) waveform at a glassy carbon electrode, operating in typical chromatographic mobile phases, is proposed for the sensitive and reproducible determination of arylethanolaminic and phenolic moiety based compounds (e.g. beta-agonists and polyphenols). Preliminary experiments by cyclic voltammetry were carried out to investigate the electrochemical behaviour and to select the detection and cleaning electrode potentials. The proposed potential-time profile was designed to prevent the carbon electrode fouling under repeated analyses, thus ensuring a reproducible and sensitive quantitative determination, without the need of any mechanical or chemical electrode cleaning procedure. The waveform electrochemical parameters, including detection and delay times, were optimized in terms of sensitivity, limit of detection and response stability. The optimized waveform allowed the sensitive and stable detection of model compounds, such as clenbuterol and caffeic acid, that showed detection limits of 0.1 μg L(-1) and 14 μg L(-1), quantification limits of 0.4 μg L(-1) and 46 μg L(-1), and linearity up to 100 μg L(-1) (r = 0.9993) and 10 mg L(-1) (r = 0.9998), respectively. Similar results were obtained for other compounds of the same classes, with precision values under repeatability conditions ranging from 3.0 to 5.9%. The proposed method can be then considered as an excellent alternative to the post-column detection of beta-agonists, phenols and polyphenols. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Facile synthesized SnO2 decorated functionalized graphene modified electrode for sensitive determination of daidzein.

    Science.gov (United States)

    Fu, Yamin; Wang, Lu; Duan, Yinghao; Zou, Lina; Ye, Baoxian

    2017-06-01

    A one-step and facile method using SnCl 2 ·H 2 O as reducing agent to reduce graphene oxide (GO) was performed in the aid of poly(diallyldimethylammonium chloride) solution (PDDA). SnCl 2 ·H 2 O is not only a reducing agent for graphene oxide (GO), but also a precursor of SnO 2 . SnO 2 -PDDA-GR composite was characterized by various surface, structural and electrochemical analysis techniques, such as transmission electron microscopy (TEM), UV spectrum (UV-vis), Infrared Spectrum (IR), X-ray diffraction (XRD), Cyclic voltammograms (CV) and electrochemical impedance (EIS). The SnO 2 -PDDA-GR composite was used to constructed electrochemical sensor (SnO 2 -PDDA-GR/GCE) for the determination of daidzein. Under the optimized experimental condition, it was found that the response of peak current is linear to the concentration of daidzein in the ranges of 2.0×10 -8 -1.0×10 -6 molL -1 , and the detection limit was estimated to be 6.7×10 -9 mol L -1 (S/N=3). Furthermore, this sensor was successfully applied for the determination of daidzein in traditional Chinese medicine (pueraria lobata) and Daidzein tablets. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A very sensitive LSC procedure to determine Ni-63 in environmental samples, steel and concrete

    International Nuclear Information System (INIS)

    Scheuerer, C.; Schupfner, R.; Schuettelkopf, H.

    1995-01-01

    This procedure to determine Ni-63 contributes to a safe and economically reasonable decommissioning of nuclear power plants. Co-60, Fe-55 and Ni-63 are the most abundant long-lived radionuclides associated with contaminated piping, hardware and concrete for a period of several decades of years after shutdown. Samples are carefully ashed leached, or dissolved by suitable mixtures of acids. The analysis starts with the absorption Ni 2+ on the chelating resin CHELEX 100. The next purification steps include an anionic exchange column and a precipitation as Ni-dimethyl-glyoxime, which is extracted into chloroform. After reextraction with sulfuric acid the solution containing Ni 2+ is mixed with a scintillation cocktail and counted in an anticoincidence shielded LSC. The decontamination factors are determined for all important artificially and naturally occurring radionuclides ranging form above 10 4 to 10 9 . The chemical yield adopts a value of (95±5)%. Up to maximum sample amounts of 0.4 g steel, 5 g concrete and about 100 g of environmental samples the detection limits are about 5 mBq per sample or 12 mBq/g steel, 1 mBq/g concrete and 0.05 mBq/g environmental sample at a counting time of 1000 minutes. (author) 16 refs.; 2 figs.; 2 tabs

  17. Tree cover in Central Africa: determinants and sensitivity under contrasted scenarios of global change.

    Science.gov (United States)

    Aleman, Julie C; Blarquez, Olivier; Gourlet-Fleury, Sylvie; Bremond, Laurent; Favier, Charly

    2017-01-30

    Tree cover is a key variable for ecosystem functioning, and is widely used to study tropical ecosystems. But its determinants and their relative importance are still a matter of debate, especially because most regional and global analyses have not considered the influence of agricultural practices. More information is urgently needed regarding how human practices influence vegetation structure. Here we focused in Central Africa, a region still subjected to traditional agricultural practices with a clear vegetation gradient. Using remote sensing data and global databases, we calibrated a Random Forest model to correlatively link tree cover with climatic, edaphic, fire and agricultural practices data. We showed that annual rainfall and accumulated water deficit were the main drivers of the distribution of tree cover and vegetation classes (defined by the modes of tree cover density), but agricultural practices, especially pastoralism, were also important in determining tree cover. We simulated future tree cover with our model using different scenarios of climate and land-use (agriculture and population) changes. Our simulations suggest that tree cover may respond differently regarding the type of scenarios, but land-use change was an important driver of vegetation change even able to counterbalance the effect of climate change in Central Africa.

  18. A sensitive enzyme-linked immunosorbent assay for the determination of fish protein in processed foods.

    Science.gov (United States)

    Shibahara, Yusuke; Uesaka, Yoshihiko; Wang, Jun; Yamada, Shoichi; Shiomi, Kazuo

    2013-01-15

    Fish is one of the most common causes of food allergy and its major allergen is parvalbumin, a 12 kDa muscular protein. In this study, a sandwich enzyme-linked immunosorbent assay (ELISA) for the determination of fish protein in processed foods was developed using a polyclonal antibody raised against Pacific mackerel parvalbumin. The developed sandwich ELISA showed 22.6-99.0% reactivity (based on the reactivity to Pacific mackerel parvalbumin) to parvalbumins from various species of fish. The limits of detection and quantitation were estimated to be 0.23 and 0.70 μg protein per g of food, respectively. When the sandwich ELISA was subjected to inter-laboratory validation, spiked fish protein was recovered from five model processed foods in the range of 69.4-84.8% and the repeatability and reproducibility relative standard deviations were satisfactorily low (≤ 10.5%). Thus, the sandwich ELISA was judged to be a useful tool to determine fish protein in processed foods. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Highly selective and sensitive determination of copper ion by two novel optical sensors

    Directory of Open Access Journals (Sweden)

    Mehrorang Ghaedi

    2017-05-01

    Full Text Available New optical sensors for the determination of copper ion by incorporation of 1,1′-(4-nitro-1,2-phenylenebis(azan-1-yl-1-ylidenebis(methan-1-yl-1-lidenedinaphthalen-2-ol(L1, 1,1′-2,2′-(1,2-phenylenebis(ethene-2,1-diyldinaphthalen-2-ol 1(L2, dibutylphthalate (DBP and sodium tetraphenylborate (Na-TPB to the plasticized polyvinyl chloride matrices were prepared. The tendency of both ionophores (L2 and L1 as chromoionophore was significantly enhanced by the addition of DBP to the membrane. The proposed sensors benefit from advantages such as high stability, reproducibility and relatively long lifetime, good selectivity for Cu2+ ion determination over a large number of alkali, alkaline earth, transition and heavy metal ions. At optimum values of membrane compositions and experimental conditions, both sensors’ response was linear over a concentration range of 7.98 × 10−6 to 1.31 × 10−4mol L−1 and 1.99 × 10−6 to 5.12 × 10−5 mol L−1 for L2 and L1, respectively. Sensor detection limit based on the definition that the concentration of the sample leads to a signal equal to the blank signal plus three times of its standard deviation was found to be 3.99 × 10−7 and 5.88 × 10−7 mol L−1 for L2 and L1, respectively. The response time of the optodes (defined as the time required reaching the 90% of the peak signal was found to be 5–8 min for L2 and 20–25 min for L1 based sensor. The proposed optical sensors were applied successfully for the determination of Cu2+ ion content in water samples.

  20. Aluminium sensitized spectrofluorimetric determination of fluoroquinolones in milk samples coupled with salting-out assisted liquid-liquid ultrasonic extraction

    Science.gov (United States)

    Xia, Qinghai; Yang, Yaling; Liu, Mousheng

    2012-10-01

    An aluminium sensitized spectrofluorimetric method coupled with salting-out assisted liquid-liquid ultrasonic extraction for the determination of four widely used fluoroquinolones (FQs) namely norfloxacin (NOR), ofloxacin (OFL), ciprofloxacin (CIP) and gatifloxacin (GAT) in bovine raw milk was described. The analytical procedure involves the fluorescence sensitization of aluminium (Al3+) by complexation with FQs, salting-out assisted liquid-liquid ultrasonic extraction (SALLUE), followed by spectrofluorometry. The influence of several parameters on the extraction (the salt species, the amount of salt, pH, temperature and phase volume ratio) was investigated. Under optimized experimental conditions, the detection limits of the method in milk varied from 0.009 μg/mL for NOR to 0.016 μg/mL for GAT (signal-to-noise ratio (S/N) = 3). The relative standard deviations (RSD) values were found to be relatively low (0.54-2.48% for four compounds). The calibration graph was linear from 0.015 to 2.25 μg/mL with coefficient of determinations not less than 0.9974. The methodology developed was applied to the determination of FQs in bovine raw milk samples. The main advantage of this method is simple, accurate and green. The method showed promising applications for analyzing polar analytes especially polar drugs in various sample matrices.

  1. Determination of sensitivity of staphylococcus SPP to xeno-graft of pig to be radio-sterilized subsequently with ionizing

    International Nuclear Information System (INIS)

    Rojas Tapia, Carolina

    2011-01-01

    The use of the pork skin heterograft or xenograft, as a temporary biological dressing in the treatment of extreme burns patients, may cause a risk due to the transmission of pathogenic bacteria of the genus Staphylococcus spp colonizing the outer part of the skin. The objective of this study was to determine the sensitivity of Staphylococcus spp from porcine xenograft, against ionizing energy and by antibiogram, which was carried out in the Radio-sterilized Biological Tissue Processing Laboratory (LPTR) of the Chilean Nuclear Energy Commission, in together with the Microbiology Laboratory of the Santo Tomas University. The hides of pigs are processed to obtain sterile porcine xenograft. The determination of the radiosensitivity of Staphylococcus hyicus and epidermidis, required the use of 15 samples of pig skin of 0.5g sterile, for each species of Staphylococcus analyzed. Subsequently, the pig skins are contaminated with Staphylococcus hyicus and epidermidis. Once the contamination was finished, the samples were subjected to an irradiation dose of 0.2; 0.4; 0.6; 0.8 KGy, plus a control (without irradiation), to finally perform a microbiological count, which allowed to determine a DIO value that for Staphylococcus hyicus that was approximately 0.25KGy and for Staphylococcus epidermidis was approximately 0.29KGy. The microbial susceptibility tested by traditional antibiogram for Staphylococcus aureus, hyicus and epidermidis, allowed concluding that all staphylococci analyzed in the present study were sensitive to antibiotics: Cloxacillin, Amoxicillin + Ac clavulanic and Gentamicin, however were resistant to Penicillin and Erythromycin

  2. HB&L System: rapid determination of antibiotic sensitivity of bacteria isolated from blood cultures.

    Directory of Open Access Journals (Sweden)

    Simone Barocci

    2010-03-01

    Full Text Available Introduction. Blood culture is an important method to detect microbial pathogens on blood, very useful for diagnosing bacterial infections. Unfortunately, classical diagnostic protocols cannot directly identify bacteria responsible for sepsis and accordingly their antimicrobial profiles. This problem causes a delay of almost two days in the availability of a specific antimicrobial profile. Objective. Among the main causes of death, sepsis have a relevant importance. For this reason it is important both to identify pathogens and to perform an antimicrobial susceptibility test in the shortest time as possible. For this purpose, the main aim of this study is the evaluation of the performances of an antimicrobial susceptibility determination directly performed on positive blood cultures. Materials and methods. This study has been performed on 70 positive blood cultures, during the period from January to July 2009. A number of 35 blood cultures were positive for Gram negative bacteria, and 35 were positive for Gram positive bacteria. From these positive blood cultures, after a short sample preparation, it has been possible to directly determine antimicrobial susceptibility profiles by using the HB&L (formerly URO-QUICK instrument. Results. The HB&L system results showed a very good correlation with both the classical disk diffusion method and VITEK 2 automatic system.The performances between the methods carried out in this study were equivalent. Conclusions. From data reported, thanks to the rapidity and simplicity of the method used, we can assert that the direct susceptibility test available with the HB&L system, is useful for a rapid and early choice of the antibiotic treatment.

  3. Magnetic multiwalled carbon nanotubes as nanocarrier tags for sensitive determination of fetuin in saliva.

    Science.gov (United States)

    Sánchez-Tirado, Esther; González-Cortés, Araceli; Yáñez-Sedeño, Paloma; Pingarrón, José M

    2018-08-15

    This paper reports the development and performance of an electrochemical immunosensor using magnetic multiwalled carbon nanotubes (m-MWCNTs) as nanocarrier tags for the determination of human fetuin A (HFA), a relevant biomarker of obesity, insulin resistance, and type-2 diabetes as well as for pancreatic and liver cancers and inflammatory processes. Screen-printed carbon electrodes were grafted with p-aminobezoic acid and streptavidin was covalently immobilized on the electrode surface. A biotinylated capture antibody was immobilized through streptavidin-biotin interaction and a sandwich assay configuration was implemented using m-MWCNTs conjugated with HRP and anti-HFA antibodies as the detection label. The determination of HFA was accomplished by measuring the current produced by the electrochemical reduction of benzoquinone at -200 mV upon addition of H 2 O 2 as HRP substrate. The prepared m-MWCNTs were characterized by SEM, TEM, XRD and EDS. All the steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy and cyclic voltammetry. A linear calibration plot for HFA was found between 20 and 2000 pg/mL with a LOD value of 16 pg/mL. This performance is notably better than that reported for an ELISA kit and a chronoimpedimetric immunosensor. The favorable contribution of m-MWCNTs in comparison with MWCNTs without incorporated magnetic particles to this excellent analytical performance is also highlighted. The immunosensor selectivity against other proteins and potentially interfering compounds was excellent. In addition, the usefulness of the immunosensor was demonstrated by the analysis of HFA in saliva with minimal sample treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. A haploid genetic screen identifies the G1/S regulatory machinery as a determinant of Wee1 inhibitor sensitivity.

    Science.gov (United States)

    Heijink, Anne Margriet; Blomen, Vincent A; Bisteau, Xavier; Degener, Fabian; Matsushita, Felipe Yu; Kaldis, Philipp; Foijer, Floris; van Vugt, Marcel A T M

    2015-12-08

    The Wee1 cell cycle checkpoint kinase prevents premature mitotic entry by inhibiting cyclin-dependent kinases. Chemical inhibitors of Wee1 are currently being tested clinically as targeted anticancer drugs. Wee1 inhibition is thought to be preferentially cytotoxic in p53-defective cancer cells. However, TP53 mutant cancers do not respond consistently to Wee1 inhibitor treatment, indicating the existence of genetic determinants of Wee1 inhibitor sensitivity other than TP53 status. To optimally facilitate patient selection for Wee1 inhibition and uncover potential resistance mechanisms, identification of these currently unknown genes is necessary. The aim of this study was therefore to identify gene mutations that determine Wee1 inhibitor sensitivity. We performed a genome-wide unbiased functional genetic screen in TP53 mutant near-haploid KBM-7 cells using gene-trap insertional mutagenesis. Insertion site mapping of cells that survived long-term Wee1 inhibition revealed enrichment of G1/S regulatory genes, including SKP2, CUL1, and CDK2. Stable depletion of SKP2, CUL1, or CDK2 or chemical Cdk2 inhibition rescued the γ-H2AX induction and abrogation of G2 phase as induced by Wee1 inhibition in breast and ovarian cancer cell lines. Remarkably, live cell imaging showed that depletion of SKP2, CUL1, or CDK2 did not rescue the Wee1 inhibition-induced karyokinesis and cytokinesis defects. These data indicate that the activity of the DNA replication machinery, beyond TP53 mutation status, determines Wee1 inhibitor sensitivity, and could serve as a selection criterion for Wee1-inhibitor eligible patients. Conversely, loss of the identified S-phase genes could serve as a mechanism of acquired resistance, which goes along with development of severe genomic instability.

  5. Alteration in lipid composition of plasma membranes of sensitive and resistant Guerin carcinoma cells due to the action of free and liposomal form of cisplatin.

    Science.gov (United States)

    Naleskina, L A; Todor, I N; Nosko, M M; Lukianova, N Y; Pivnyuk, V M; Chekhun, V F

    2013-09-01

    To study in vivo changes of lipid composition of plasma membranes of sensitive and resistant to cisplatin Guerin carcinoma cells under influence of free and liposomal cisplatin forms. The isolation of plasma membranes from parental (sensitive) and resistant to cisplatin Guerin carcinoma cells was by differential ultracentrifugation in sucrose density gradient. Lipids were detected by method of thin-layer chromatography. It was determined that more effective action of cisplatin liposomal form on resistant cells is associated with essential abnormalities of conformation of plasma membrane due to change of lipid components and architectonics of rafts. It results in the increase of membrane fluidity. Reconstructions in lipid composition of plasma membranes of cisplatin-resistant Guerin carcinoma cells provide more intensive delivery of drug into the cells, increase of its concentration and more effective interaction with cellular structural elements.

  6. Highly sensitive determination of mercury using copper enhancer by diamond electrode coupled with sequential injection–anodic stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Chaiyo, Sudkate [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand); Chailapakul, Orawon [Department of Chemistry, Faculty of Science, Chulalongkorn University (Thailand); Center for Petroleum, Petrochemicals, and Advanced Materials, Chulalongkorn University (Thailand); Siangproh, Weena, E-mail: weena@swu.ac.th [Department of Chemistry, Faculty of Science, Srinakharinwirot University (Thailand)

    2014-12-10

    Highlights: • Highly sensitive determination of Hg(II) using SI–ASV-BDD was achieved. • Electrochemical detection of Hg(II) using Cu(II) enhancer was accomplished. • LOD and LOQ were found to be very low at 40.0 ppt and 135.0 ppt. • This method was successfully applied for determination of Hg(II) in real samples. - Abstract: A highly sensitive determination of mercury in the presence of Cu(II) using a boron-doped diamond (BDD) thin film electrode coupled with sequential injection–anodic stripping voltammetry (SI–ASV) was proposed. The Cu(II) was simultaneously deposited with Hg(II) in a 0.5 M HCl supporting electrolyte by electrodeposition. In presence of an excess of Cu(II), the sensitivity for the determination of Hg(II) was remarkably enhanced. Cu(II) and Hg(II) were on-line deposited onto the BDD electrode surface at −1.0 V (vs. Ag/AgCl, 3 M KCl) for 150 s with a flow rate of 14 μL s{sup −1}. An anodic stripping voltammogram was recorded from −0.4 V to 0.25 V using a frequency of 60 Hz, an amplitude of 50 mV, and a step potential of 10 mV at a stopped flow. Under the optimal conditions, well-defined peaks of Cu(II) and Hg(II) were found at −0.25 V and +0.05 V (vs. Ag/AgCl, 3 M KCl), respectively. The detection of Hg(II) showed two linear dynamic ranges (0.1–30.0 ng mL{sup −1} and 5.0–60.0 ng mL{sup −1}). The limit of detection (S/N = 3) obtained from the experiment was found to be 0.04 ng mL{sup −1}. The precision values for 10 replicate determinations were 1.1, 2.1 and 2.9% RSD for 0.5, 10 and 20 ng mL{sup −1}, respectively. The proposed method has been successfully applied for the determination of Hg(II) in seawater, salmon, squid, cockle and seaweed samples. A comparison between the proposed method and an inductively coupled plasma optical emission spectrometry (ICP-OES) standard method was performed on the samples, and the concentrations obtained via both methods were in agreement with the certified values of Hg

  7. Basic processes and factors determining the evolution of collapse sinkholes: a sensitivity study

    Science.gov (United States)

    Romanov, Douchko; Kaufmann, Georg

    2017-04-01

    Collapse sinkholes appear as closed depressions at the surface. The origin of these karst features is related to the continuous dissolution of the soluble rock caused by a focussed sub-surface flow. Water flowing along a preferential pathway through fissures and fractures within the phreatic part of a karst aquifer is able to dissolve the rock (limestone, gypsum, anhydrite). With time, the dissolved void volume increases and part of the ceiling above the stream can become unstable, collapses, and accumulates as debris in the flow path. The debris partially blocks the flow and thus activates new pathways. Because of the low compaction of the debris (high hydraulic conductivity), the flow and the dissolution rates within this crushed zone remain high. This allows a relatively fast dissolutional and erosional removal of the crushed material and the development of new empty voids. The void volume expands upwards towards the surface until a collapse sinkhole is formed. The collapse sinkholes exhibit a large variety of shapes (cylindrical, cone-, bowl-shaped), depths (from few to few hundred meters) and diameters (meters up to hundreds of meters). Two major processes are responsible for this diversity: a) the karst evolution of the aquifer - responsible for the dissolutional and erosional removal of material; b) the mechanical evolution of the host rock and the existence of structural features, faults for example, which determine the stability and the magnitude of the subsequent collapses. In this work we demonstrate the influence of the host rock type, the hydrological and geological boundary conditions, the chemical composition of the flowing water, and the geometry and the scale of the crushed zone, on the location and the evolution of the growing sinkhole. We demonstrate the ability of the karst evolution models to explain, at least qualitatively, the growth and the morphology of the collapse sinkholes and to roughly predict their shape and location. Implementing

  8. Nitrogen-Doped Carbon Dots as A New Substrate for Sensitive Glucose Determination

    Directory of Open Access Journals (Sweden)

    Hanxu Ji

    2016-05-01

    Full Text Available Nitrogen-doped carbon dots are introduced as a novel substrate suitable for enzyme immobilization in electrochemical detection metods. Nitrogen-doped carbon dots are easily synthesised from polyacrylamide in just one step. With the help of the amino group on chitosan, glucose oxidase is immobilized on nitrogen-doped carbon dots-modified carbon glassy electrodes by amino-carboxyl reactions. The nitrogen-induced charge delocalization at nitrogen-doped carbon dots can enhance the electrocatalytic activity toward the reduction of O2. The specific amino-carboxyl reaction provides strong and stable immobilization of GOx on electrodes. The developed biosensor responds efficiently to the presence of glucose in serum samples over the concentration range from 1 to 12 mM with a detection limit of 0.25 mM. This novel biosensor has good reproducibility and stability, and is highly selective for glucose determination under physiological conditions. These results indicate that N-doped quantum dots represent a novel candidate material for the construction of electrochemical biosensors.

  9. A fast and very sensitive LSC procedure to determine Fe-55 in steel and concrete

    International Nuclear Information System (INIS)

    Koenig, W.; Schupfner, R.; Schuettelkopf, H.

    1995-01-01

    This procedure determining Fe-55 contributes to a safe and economically reasonable decommissioning of nuclear power plants. Co-60, Fe-55 and Ni-63 are the most abundant, long-lived radionuclides associated with contaminated piping, hardware, and concrete for several decades of years after shutdown. The analysis of Fe takes about three hours until the measurement with an anticoincidence shielded LSC Quantulus 1220 starts. The decontamination factors are ranging from greater than 10 5 to 10 9 for all important naturally and artificially occurring radionuclides except Sb. The chemical yield stays constant at a value of about 92% up to 0.1 g stable Fe in steel, concrete or other material. The detection limits (confidence level 95%) reach values of 8 mBq per sample or about 60 mBq/g steel and 1.5 mBq/g concrete at a counting time of 1000 minutes. Four to eight analyses are performed by one technician during eight hours. (author) 16 refs.; 2 figs.; 4 tabs

  10. Sensitivity Analysis of Hydraulic Methods Regarding Hydromorphologic Data Derivation Methods to Determine Environmental Water Requirements

    Directory of Open Access Journals (Sweden)

    Alireza Shokoohi

    2015-07-01

    Full Text Available This paper studies the accuracy of hydraulic methods in determining environmental flow requirements. Despite the vital importance of deriving river cross sectional data for hydraulic methods, few studies have focused on the criteria for deriving this data. The present study shows that the depth of cross section has a meaningful effect on the results obtained from hydraulic methods and that, considering fish as the index species for river habitat analysis, an optimum depth of 1 m should be assumed for deriving information from cross sections. The second important parameter required for extracting the geometric and hydraulic properties of rivers is the selection of an appropriate depth increment; ∆y. In the present research, this parameter was found to be equal to 1 cm. The uncertainty of the environmental discharge evaluation, when allocating water in areas with water scarcity, should be kept as low as possible. The Manning friction coefficient (n is an important factor in river discharge calculation. Using a range of "n" equal to 3 times the standard deviation for the study area, it is shown that the influence of friction coefficient on the estimation of environmental flow is much less than that on the calculation of river discharge.

  11. Polymer membrane electrodes for sensitive potentiometric determination of beta-blockers.

    Science.gov (United States)

    Wassil, Anwar A; Farag, Abd El-Ftaah Bastawy; Moukdad, Fatma A

    2007-01-01

    The construction of PVC matrix-type beta-blockers (sotalol, carvedilol, and betaxolol) ion selective electrodes and their use for direct potentiometry of their respective species are described. The proposed sensors are based on the complex ion associates of beta-blockers with tungstophosphate (TP) and Ammonium Reineckate (Rein) ionophoris in poly vinyl chloride membrane (PVC) with Dioctylphthalate (DOP) plasticizer. The four electrodes (Beta-TP), (Sota-TP), (Carve-TP), and (Cave-Rein) show stable potential response with near Nernstian slope of 50.8, 33.7, 32.35, and 33 mv per decade, range of concentration 10-2-10-7 M beta-blockers. Selectivity coefficients data obtained for 11 different organic and inorganic ions are presented. The electrodes have fast response time (30 and 40 s) and were used over wide range of pH 4.5-8.5. Validation of the method according to the quality assurance standers shows suitability of proposed sensors for use in the quality control assessment of these drugs. The results obtained for the determination of beta-blockers with the proposed electrodes show average recoveries of 100.78% and a mean standard deviation of +/-1.2. The nominal are obtained. The data agree well with those obtained by standard methods.

  12. Sensitivity improvements, in the determination of mercury in biological tissues by neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Cornett, C R; Samudralwar, D L; Ehmann, W D [Kentucky Univ., Lexington, KY (United States). Dept. of Chemistry; Markesbery, W R [Kentucky Univ., Lexington, KY (United States)

    1995-08-01

    The possible association of dental amalgam surface exposure, brain mercury (Hg) levels, and pathological markers of Alzheimer`s disease (AD) in the brain is the subject of an on-going study in our laboratory. Two radiochemical neutron activation analysis methods and the use of instrumental neutron activation analysis (INAA) with Compton suppression spectrometry have been evaluated for improving our INAA Hg detection limit (2.8{+-}0.6 ng/g, wet-weight basis) in human tissue. Large numbers of samples dictated the use of a purely instrumental method or rapid, simple radiochemical separations. Human brain tissues and NIST biological standards were analyzed using a precipitation of Hg{sub 2}Cl{sub 2}, a solvent extraction utilizing sodium diethyldithiocarbomate, conventional INAA, and INAA with Compton suppression. The radiochemical precipitation of Hg{sub 2}Cl{sub 2} proved to be the most useful method for use in our study because it provided a simultaneous, quantitative determination of silver (Ag) and a Hg detection limit in brain tissue of 1.6{+-}0.1 ng/g (wet-weight basis). (author). 12 refs., 2 tabs.

  13. Urinary growth hormone levels in children with leukemia determined by a sensitive sandwich enzyme immunoassay

    International Nuclear Information System (INIS)

    Umezawa, Sachiko; Yano, Hisako; Tanaka, Toshiaki; Hibi, Itsuo; Tsukimoto, Ichiro; Ishikawa, Eiji; Mouri, Yoshikazu; Murakami, Yoshiaki.

    1989-01-01

    Elective cranial irradiation in central nervous leukemia leads to a long term survival; however, the influence upon the hypothalamus and hypophysis remains uncertain. Therefore, changes in SD scores of height and urinary growth hormone (U-GH) levels were determined in 23 leukemic patients previously treated with cranial elective irradition of 18 or 24 Gy, whose ages ranged from 4 to 16 years. Decreased SD scores of height was observed in 9 (90%) of 10 patients in whom treatment has been continuing (within 5 years after the onset) and in 6 (50%) of 12 patients in whom treatment had been completed (5 years or more after the onset). The level of U-GH was significantly decreased in leukemic patients during complete remission than in healthy children. U-HG levels were independent of radiation doses. In evaluable 14 patients, the blood concentration of somatomedin C (SM-C) was within the normal range. Although there was a discrepancy between U-CH and SM-C levels, further follow-up of these leukemic patients is required. (N.K.)

  14. Antigen sensitivity is a major determinant of CD8+ T-cell polyfunctionality and HIV-suppressive activity.

    Science.gov (United States)

    Almeida, Jorge R; Sauce, Delphine; Price, David A; Papagno, Laura; Shin, So Youn; Moris, Arnaud; Larsen, Martin; Pancino, Gianfranco; Douek, Daniel C; Autran, Brigitte; Sáez-Cirión, Asier; Appay, Victor

    2009-06-18

    CD8(+) T cells are major players in the immune response against HIV. However, recent failures in the development of T cell-based vaccines against HIV-1 have emphasized the need to reassess our basic knowledge of T cell-mediated efficacy. CD8(+) T cells from HIV-1-infected patients with slow disease progression exhibit potent polyfunctionality and HIV-suppressive activity, yet the factors that unify these properties are incompletely understood. We performed a detailed study of the interplay between T-cell functional attributes using a bank of HIV-specific CD8(+) T-cell clones isolated in vitro; this approach enabled us to overcome inherent difficulties related to the in vivo heterogeneity of T-cell populations and address the underlying determinants that synthesize the qualities required for antiviral efficacy. Conclusions were supported by ex vivo analysis of HIV-specific CD8(+) T cells from infected donors. We report that attributes of CD8(+) T-cell efficacy against HIV are linked at the level of antigen sensitivity. Highly sensitive CD8(+) T cells display polyfunctional profiles and potent HIV-suppressive activity. These data provide new insights into the mechanisms underlying CD8(+) T-cell efficacy against HIV, and indicate that vaccine strategies should focus on the induction of HIV-specific T cells with high levels of antigen sensitivity to elicit potent antiviral efficacy.

  15. Highly sensitive covalently functionalized light-addressable potentiometric sensor for determination of biomarker

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jintao [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guan, Mingyuan; Huang, Guoyin; Qiu, Hengming; Chen, Zhengcheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Li, Guiyin, E-mail: liguiyin01@163.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Huang, Yong, E-mail: huangyong503@126.com [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China); Guangxi Experiment Center of Information Sciences, Guilin University of Electronic Technology, Guilin, Guangxi 541004 (China)

    2016-06-01

    A biomarker is related to the biological status of a living organism and shows great promise for the early prediction of a related disease. Herein we presented a novel structured light-addressable potentiometric sensor (LAPS) for the determination of a model biomarker, human immunoglobulin G (hIgG). In this system, the goat anti-human immunoglobulin G antibody was used as recognition element and covalently immobilized on the surface of light-addressable potentiometric sensor chip to capture human immunoglobulin G. Due to the light addressable capability of light-addressable potentiometric sensor, human immunoglobulin G dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of the sensor. In order to produce a stable photocurrent, the laser diode controlled by field-programmable gate array was used as the light emitter to drive the light-addressable potentiometric sensor. A linear correlation between the potential shift response and the concentration of human immunoglobulin G was achieved and the corresponding regression equation was ΔV (V) = 0.00714C{sub hIgG} (μg/mL)–0.0147 with a correlation coefficient of 0.9968 over a range 0–150 μg/mL. Moreover, the light-addressable potentiometric sensor system also showed acceptable stability and reproducibility. All the results demonstrated that the system was more applicable to detection of disease biomarkers with simple operation, multiple-sample format and might hold great promise in various environmental, food, and clinical applications. - Highlights: • A novel structured light-addressable potentiometric sensor (LAPS) based on covalently functionalized membrane was designed. • The composition of the surface of LAPS chip was investigated by X-ray photoelectron spectroscopy (XPS). • hIgG dissolved in the supporting electrolyte solution can be detected by monitoring the potential shifts of LAPS.

  16. Pattern of access determines influence of junk food diet on cue sensitivity and palatability.

    Science.gov (United States)

    Kosheleff, Alisa R; Araki, Jingwen; Hsueh, Jennifer; Le, Andrew; Quizon, Kevin; Ostlund, Sean B; Maidment, Nigel T; Murphy, Niall P

    2018-04-01

    Like drug addiction, cues associated with palatable foods can trigger food-seeking, even when sated. However, whether susceptibility to the motivating influence of food-related cues is a predisposing factor in overeating or a consequence of poor diet is difficult to determine in humans. Using a rodent model, we explored whether a highly palatable 'junk food' diet impacts responses to reward-paired cues in a Pavlovian-to-instrumental transfer test, using sweetened condensed milk (SCM) as the reward. The hedonic impact of SCM consumption was also assessed by analyzing licking microstructure. To probe the effects of pattern and duration of junk food exposure, we provided rats with either regular chow ad libitum (controls) or chow plus access to junk food for either 2 or 24 h per day for 1, 3, or 6 weeks. We also examined how individual susceptibility to weight gain related to these measures. Rats provided 24 h access to the junk food diet were insensitive to the motivational effects of a SCM-paired cue when tested sated even though their hedonic experience upon reward consumption was similar to controls. In contrast, rats provided restricted, 2 h access to junk food exhibited a cue generalization phenotype under sated conditions, lever-pressing with increased vigor in response to both a SCM-paired cue, and a cue not previously paired with reward. Hedonic response was also significantly higher in these animals relative to controls. These data demonstrate that the pattern of junk food exposure differentially alters the hedonic impact of palatable foods and susceptibility to the motivating influence of cues in the environment to promote food-seeking actions when sated, which may be consequential for understanding overeating and obesity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Sensitive flotation-spectrophotometric determination of gold, based on the gold(I)-iodide-methylene blue system.

    Science.gov (United States)

    Marczenko, Z; Jankowski, K

    1985-04-01

    The gold(I)-iodide-Methylene Blue (MB) system is suitable for flotation separation and spectrophotometric determination of gold. Under the optimum conditions [(MB(+))(AuI(2)(-))].3[(MB(+))(I(3)(-))] is formed, and floated with cyclohexane. The product is dissolved in methanol and its absorbance measured. The molar absorptivity is 3.4 x 10(5)1.mole(-1).cm(-1) at 655 nm. The proposed method is more than three times as sensitive as the Rhodamine B method. Pt, Pd, Ag and Hg interfere seriously, and Ir, Rh, Bi and Cd to a smaller extent. Preliminary separation of gold by precipitation with tellurium as a collector is recommended. The method has been applied to determination of gold traces (about 1 x 10(-4)%) in a copper sample.

  18. Determination of photosynthetic and enzymatic biomarkers sensitivity used to evaluate toxic effects of copper and fludioxonil in alga Scenedesmus obliquus

    Energy Technology Data Exchange (ETDEWEB)

    Dewez, David [Departement de Chimie et de Biochimie, Centre TOXEN, Universite du Quebec a Montreal, CP 8888, Succursale Centre-Ville, Montreal, Quebec, H3C 3P8 (Canada); Geoffroy, Laure [Laboratoire d' Eco-Toxicologie, Unite de recherche ' Vignes et Vins de Champagne' , UPRES-EA 2069, Universite de Reims Champagne-Ardenne BP 1039, F51687 REIMS CEDEX 2 (France); Vernet, Guy [Laboratoire d' Eco-Toxicologie, Unite de recherche ' Vignes et Vins de Champagne' , UPRES-EA 2069, Universite de Reims Champagne-Ardenne BP 1039, F51687 REIMS CEDEX 2 (France); Popovic, Radovan [Departement de Chimie et de Biochimie, Centre TOXEN, Universite du Quebec a Montreal, CP 8888, Succursale Centre-Ville, Montreal, Quebec, H3C 3P8 (Canada)]. E-mail: popovic.radovan@uqam.ca

    2005-08-30

    Modulated PAM fluorometry and Plant Efficiency Analyser methods were used to investigate photosynthetic fluorescence parameters of alga Scenedesmus obliquus exposed to inhibitory effect of fungicides copper sulphate and fludioxonil (N-(4-nitrophenyl)-N'-propyl-uree). The change of those parameters were studied when alga S. obliquus have been exposed during 48 h to different concentrations of fungicides (1, 2 and 3 mg l{sup -1}). Under the same condition, enzymatic activities of catalase, ascorbate peroxidase, glutathione reductase and glutathione S-transferase were investigated to evaluate antioxidative response to fungicides effects. The change of sensitivity of those parameters was dependent to the mode of fungicide action, their concentration and time of exposure. For copper effects, the most indicative photosynthetic biomarkers were parameters Q {sub N} as non-photochemical fluorescence quenching, Q {sub Emax} as the proton induced fluorescence quenching and ABS/RC as the antenna size per photosystem II reaction center. Copper induced oxidative stress was indicated by increased activity of catalase serving as the most sensitive and valuable enzymatic biomarker. On the other hand, fludioxonil effect on photosynthetic parameters was very negligible and consequently not very useful as biomarkers. However, fludioxonil induced strong antioxidative activities associated with cytosol enzymes, as we found for catalase, ascorbate peroxidase and glutathione S-transferase activities. By obtained results, we may suggest for the activation of those enzymes to be sensitive and valuable biomarkers of oxidative stress induced by fludioxonil. Determination of biomarkers sensitivity may offer advantages in providing real criteria to use them for ecotoxicological diagnostic studies.

  19. Apomorphine conditioning and sensitization: the paired/unpaired treatment order as a new major determinant of drug conditioned and sensitization effects.

    Science.gov (United States)

    de Matos, Liana Wermelinger; Carey, Robert J; Carrera, Marinete Pinheiro

    2010-09-01

    Repeated treatments with psychostimulant drugs generate behavioral sensitization. In the present study we employed a paired/unpaired protocol to assess the effects of repeated apomorphine (2.0 mg/kg) treatments upon locomotion behavior. In the first experiment we assessed the effects of conditioning upon apomorphine sensitization. Neither the extinction of the conditioned response nor a counter-conditioning procedure in which we paired an inhibitory treatment (apomorphine 0.05 mg/kg) with the previously established conditioned stimulus modified the sensitization response. In the second experiment, we administered the paired/unpaired protocol in two phases. In the second phase, we reversed the paired/unpaired protocol. Following the first phase, the paired group alone exhibited conditioned locomotion in the vehicle test and a sensitization response. In the second phase, the initial unpaired group which received 5 paired apomorphine trials during the reversal phase did not develop a conditioned response but developed a potentiated sensitization response. This disassociation of the conditioned response from the sensitization response is attributed to an apomorphine anti-habituation effect that can generate a false positive Pavlovian conditioned response effect. The potentiated sensitization response induced by the treatment reversal protocol points to an important role for the sequential experience of the paired/unpaired protocol in behavioral sensitization. 2010 Elsevier Inc. All rights reserved.

  20. Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Juanjuan; Liu, Maoxiang [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Song, Haiou, E-mail: songhaiou2011@126.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Zhang, Shupeng, E-mail: shupeng_2006@126.com [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Qian, Yueyue [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Aimin, E-mail: liaimin@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

    2016-11-15

    Highlights: • Phenol detection based on coupled cMWCNT/CD edge-functionalized graphene composite. • Increased conductivity can inspire enhancement of electrocatalytic performance. • The synergistic combination of the trace amounts of CDs and cMWCNT is a pivotal. • GN-CD-cMWCNT shows an excellent electrocatalytic and anti-interference ability. - Abstract: Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027 μM (S/N = 3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

  1. Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

    International Nuclear Information System (INIS)

    Gao, Juanjuan; Liu, Maoxiang; Song, Haiou; Zhang, Shupeng; Qian, Yueyue; Li, Aimin

    2016-01-01

    Highlights: • Phenol detection based on coupled cMWCNT/CD edge-functionalized graphene composite. • Increased conductivity can inspire enhancement of electrocatalytic performance. • The synergistic combination of the trace amounts of CDs and cMWCNT is a pivotal. • GN-CD-cMWCNT shows an excellent electrocatalytic and anti-interference ability. - Abstract: Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027 μM (S/N = 3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

  2. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode

    International Nuclear Information System (INIS)

    Kalambate, Pramod K.; Rawool, Chaitali R.; Karna, Shashi P.; Srivastava, Ashwini K.

    2016-01-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (I p ) current for MM is found to be rectilinear in the range 4.0 × 10 −8 –2.0 × 10 −5 M with a detection limit of 7.1 × 10 −9 M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. - Highlights: • Voltammetric sensor for methylergometrine maleate using carbon nanofibers and silver nanoparticle - carbon paste electrode • Wide working range, good reproducibility, fast response and high stability were the main advantages of the proposed sensor • Analysis of methylergometrine maleate in pharmaceutical formulations, urine and blood serum samples • Lowest limit of detection obtained for methylergometrine maleate

  3. Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Ammar, Hafedh Belhadj, E-mail: hbelhadjammar@yahoo.fr; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

    2016-02-01

    The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH 11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2–4.2 μmol L{sup −1}, with a detection limit of 0.065 μmol L{sup −1}. - Highlights: • SWV for the determination of MTZ • Boron-doped diamond as a new electrochemical sensor • Simple and rapid detection of MTZ • Efficiency of BDD for sensitive determination of MTZ.

  4. Boron doped diamond sensor for sensitive determination of metronidazole: Mechanistic and analytical study by cyclic voltammetry and square wave voltammetry

    International Nuclear Information System (INIS)

    Ammar, Hafedh Belhadj; Brahim, Mabrouk Ben; Abdelhédi, Ridha; Samet, Youssef

    2016-01-01

    The performance of boron-doped diamond (BDD) electrode for the detection of metronidazole (MTZ) as the most important drug of the group of 5-nitroimidazole was proven using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. A comparison study between BDD, glassy carbon and silver electrodes on the electrochemical response was carried out. The process is pH-dependent. In neutral and alkaline media, one irreversible reduction peak related to the hydroxylamine derivative formation was registered, involving a total of four electrons. In acidic medium, a prepeak appears probably related to the adsorption affinity of hydroxylamine at the electrode surface. The BDD electrode showed higher sensitivity and reproducibility analytical response, compared with the other electrodes. The higher reduction peak current was registered at pH 11. Under optimal conditions, a linear analytical curve was obtained for the MTZ concentration in the range of 0.2–4.2 μmol L"−"1, with a detection limit of 0.065 μmol L"−"1. - Highlights: • SWV for the determination of MTZ • Boron-doped diamond as a new electrochemical sensor • Simple and rapid detection of MTZ • Efficiency of BDD for sensitive determination of MTZ

  5. Sensitive determination of pyrrolizidine alkaloids in Tussilago farfara L. by field-amplified, sample-stacking, sweeping micellar electrokinetic chromatography.

    Science.gov (United States)

    Cao, Kun; Xu, Yi; Mu, Xiuni; Zhang, Qing; Wang, Renjie; Lv, Junjiang

    2016-11-01

    Pyrrolizidine alkaloids are the toxic components in Tussilago farfara L. Due to the lack of standard substances for quantitative analysis and traces of pyrrolizidine alkaloids in total alkaloids, the full quality control of Tussilago farfara L has been limited. In this study, we aimed to solve the difficulty of determination of pyrrolizidine alkaloids and identify more components in the total alkaloids. An on-line preconcentration method has been applied to improve determining sensitivity of pyrrolizidine alkaloids in Tussilago farfara L. in which included field-amplified sample stacking and sweeping in micellar electrokinetic capillary chromatography. The main parameters that affected separation and stacking efficiency were investigated in details. Under the optimal conditions, the sensitivity enhancement factors obtained by the developed method for the analytes were from 15- to 12-fold, the limits of detection of senkirkine and senecionine were 2∼5 μg/L. Senkirkine and senecionine have been detected in alkaloids (c) of Tussilago farfara L, along ferulic acid methyl ester and methyl caffeate. The developed method was also applied to the analysis of acid extraction (a) of Tussilago farfara L, and senkirkine could be detected directly. The results indicated that the developed method is feasible for the analysis of pyrrolizidine alkaloids in Tussilago farfara L with good recoveries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. High-sensitivity determination of Zn(II) and Cu(II) in vitro by fluorescence polarization

    Science.gov (United States)

    Thompson, Richard B.; Maliwal, Badri P.; Feliccia, Vincent; Fierke, Carol A.

    1998-04-01

    Recent work has suggested that free Cu(II) may play a role in syndromes such as Crohn's and Wilson's diseases, as well as being a pollutant toxic at low levels to shellfish and sheep. Similarly, Zn(II) has been implicated in some neural damage in the brain resulting from epilepsy and ischemia. Several high sensitivity methods exist for determining these ions in solution, including GFAAS, ICP-MS, ICP-ES, and electrochemical techniques. However, these techniques are generally slow and costly, require pretreatment of the sample, require complex instruments and skilled personnel, and are incapable of imaging at the cellular and subcellular level. To address these shortcomings we developed fluorescence polarization (anisotropy) biosensing methods for these ions which are very sensitivity, highly selective, require simple instrumentation and little pretreatment, and are inexpensive. Thus free Cu(II) or Zn(II) can be determined at picomolar levels by changes in fluorescence polarization, lifetime, or wavelength ratio using these methods; these techniques may be adapted to microscopy.

  7. Sensitivity analysis

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003741.htm Sensitivity analysis To use the sharing features on this page, please enable JavaScript. Sensitivity analysis determines the effectiveness of antibiotics against microorganisms (germs) ...

  8. Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment.

    Science.gov (United States)

    Yin, Changhai; Iqbal, Jibran; Hu, Huilian; Liu, Bingxiang; Zhang, Lei; Zhu, Bilin; Du, Yiping

    2012-09-30

    A simple, sensitive and selective solid phase reflectometry method is proposed for the determination of trace mercury in aqueous samples. The complexation reagent dithizone was firstly injected into the properly buffered solution with vigorous stirring, which started a simultaneous formation of nanoparticles suspension of dithizone and its complexation reaction with the mercury(II) ions to make Hg-dithizone nanoparticles. After a definite time, the mixture was filtered with membrane, and then quantified directly on the surface of the membrane by using integrating sphere accessory of the UV-visible spectrophotometer. The quantitative analysis was carried out at a wavelength of 485 nm since it yielded the largest difference in diffuse reflectance spectra before and after reaction with mercury(II).A good linear correlation in the range of 0.2-4.0 μg/L with a squared correlation coefficient (R(2)) of 0.9944 and a detection limit of 0.12 μg/L were obtained. The accuracy of the method was evaluated by the analysis of spiked mercury(II) concentrations determined using this method along with those determined by the atomic fluorescence mercury vapourmeter and the results obtained were in good agreement. The proposed method was applied to the determination of mercury in tap water and river water samples with the recovery in an acceptable range (95.7-105.3%). Copyright © 2012 Elsevier B.V. All rights reserved.

  9. A Modified LC/MS/MS Method with Enhanced Sensitivity for the Determination of Scopolamine in Human Plasma

    Science.gov (United States)

    Wang, Zuwei; Vaksman, Zalman; Putcha, Lakshmi

    2008-01-01

    Intranasal scopolamine is a choice drug for the treatment of motion sickness during space flight because of its quick onset of action, short half-life and favorable sideeffects profile. The dose administered usually ranges between 0.1 and 0.4 mg. Such small doses make it difficult to detect concentrations of scopolamine in biological fluids using existing sensitive LC/MS/MS method, especially when the biological sample volumes are limited. To measure scopolamine in human plasma to facilitate pharmacokinetic evaluation of the drug, we developed a sensitive LC/MS/MS method using 96 well micro elution plates for solid phase extraction (SPE) of scopolamine in human plasma. Human plasma (100-250 micro L) were loaded onto Waters Oasis HLB 96 well micro elution plate and eluted with 50 L of organic solvent without evaporation and reconstitution. HPLC separation of the eluted sample was performed using an Agilent Zorbax SB-CN column (50 x 2.1 mm) at a flow rate of 0.2 mL/min for 3 minutes. The mobile phase for separation was 80:20 (v/v) methanol: ammonium acetate (30 mM) in water. Concentrations of scopolamine were determined using a Micromass Quattro Micro(TM) mass spectrometer with electrospray ionization (ESI). ESI mass spectra were acquired in positive ion mode with multiple reaction monitoring for the determination of scopolamine m/z = 304.2 right arrow 138.1 and internal standard hyoscyamine m/z = 290.2 right arrow 124.1. The method is rapid, reproducible, specific and has the following parameters: scopolamine and the IS are eluted at about 1.1 and 1.7 min respectively. The linear range is 25-10000 pg/mL for scopolamine in human plasma with correlation coefficients greater than 0.99 and CV less than 0.5%. The intra-day and inter-day CVs are less than 15% for quality control samples with concentrations of 75,300, and 750 pg/mL of scopolamine in human plasma. SPE using 96 well micro elution plates allows rapid sample preparation and enhanced sensitivity for the LC

  10. Highly sensitive electrochemical determination of 1-naphthol based on high-index facet SnO2 modified electrode

    International Nuclear Information System (INIS)

    Huang Xiaofeng; Zhao Guohua; Liu Meichuan; Li Fengting; Qiao Junlian; Zhao Sichen

    2012-01-01

    Highlights: ► It is the first time to employ high-index faceted SnO 2 in electrochemical analysis. ► High-index faceted SnO 2 has excellent electrochemical activity toward 1-naphthol. ► Highly sensitive determination of 1-naphthol is realized on high-index faceted SnO 2 . ► The detection limit of 1-naphthol is as low as 5 nM on high-index faceted SnO 2 . ► Electro-oxidation kinetics for 1-napthol on the novel electrode is discussed. - Abstract: SnO 2 nanooctahedron with {2 2 1} high-index facet (HIF) was synthesized by a simple hydrothermal method, and was firstly employed to sensitive electrochemical sensing of a typical organic pollutant, 1-naphthol (1-NAP). The constructed HIF SnO 2 modified glassy carbon electrode (HIF SnO 2 /GCE) possessed advantages of large effective electrode area, high electron transfer rate, and low charge transfer resistance. These improved electrochemical properties allowed the high electrocatalytic performance, high effective active sites and high adsorption capacity of 1-NAP on HIF SnO 2 /GCE. Cyclic voltammetry (CV) results showed that the electrochemical oxidation of 1-NAP obeyed a two-electron transfer process and the electrode reaction was under diffusion control on HIF SnO 2 /GCE. By adopting differential pulse voltammetry (DPV), electrochemical detection of 1-NAP was conducted on HIF SnO 2 /GCE with a limit of detection as low as 5 nM, which was relatively low compared to the literatures. The electrode also illustrated good stability in comparison with those reported value. Satisfactory results were obtained with average recoveries in the range of 99.7–103.6% in the real water sample detection. A promising device for the electrochemical detection of 1-NAP with high sensitivity has therefore been provided.

  11. Electron spin resonance as a high sensitivity technique for environmental magnetism: determination of contamination in carbonate sediments

    Science.gov (United States)

    Crook, Nigel P.; Hoon, Stephen R.; Taylor, Kevin G.; Perry, Chris T.

    2002-05-01

    This study investigates the application of high sensitivity electron spin resonance (ESR) to environmental magnetism in conjunction with the more conventional techniques of magnetic susceptibility, vibrating sample magnetometry (VSM) and chemical compositional analysis. Using these techniques we have studied carbonate sediment samples from Discovery Bay, Jamaica, which has been impacted to varying degrees by a bauxite loading facility. The carbonate sediment samples contain magnetic minerals ranging from moderate to low concentrations. The ESR spectra for all sites essentially contain three components. First, a six-line spectra centred around g = 2 resulting from Mn2+ ions within a carbonate matrix; second a g = 4.3 signal from isolated Fe3+ ions incorporated as impurities within minerals such as gibbsite, kaolinite or quartz; third a ferrimagnetic resonance with a maxima at 230 mT resulting from the ferrimagnetic minerals present within the bauxite contamination. Depending upon the location of the sites within the embayment these signals vary in their relative amplitude in a systematic manner related to the degree of bauxite input. Analysis of the ESR spectral components reveals linear relationships between the amplitude of the Mn2+ and ferrimagnetic signals and total Mn and Fe concentrations. To assist in determining the origin of the ESR signals coral and bauxite reference samples were employed. Coral representative of the matrix of the sediment was taken remote from the bauxite loading facility whilst pure bauxite was collected from nearby mining facilities. We find ESR to be a very sensitive technique particularly appropriate to magnetic analysis of ferri- and para-magnetic components within environmental samples otherwise dominated by diamagnetic (carbonate) minerals. When employing typical sample masses of 200 mg the practical detection limit of ESR to ferri- and para-magnetic minerals within a diamagnetic carbonate matrix is of the order of 1 ppm and 1 ppb

  12. A sensitive and quantitative biosensing method for the determination of {gamma}-ray emitting radionuclides in surface water

    Energy Technology Data Exchange (ETDEWEB)

    Wolterbeek, H.Th.; Meer, A.J.G.M. van der [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.

    1996-11-01

    A quantitative and sensitive biosensing method has been developed for the determination of {gamma}-ray emitting radionuclides in surface water. The method is based on the concept that at equilibrium the specific radioactivity in the biosensor is equal to the specific radioactivity in water. The method consists of the measurement of both the radionuclide and the element in the biosensor and the determination of the element level in water. This three-way analysis eliminates problems such as unpredictable biosensor behaviour, effects of water elemental composition or further abiotic parameters: what remains is the generally high enrichment (bioaccumulation factor BCF) of elements and radionuclides in the biosensor material. Measurements were performed with floating water plants (Azolla filiculoides Lamk., Spirodela polyrhiza/Lemna sp.) and the fully submerged water plant Ceratophyllum demersum L., which were sampled from ditch water. Concentrations of elements and radionuclides were determined in both water and biosensor plants, using Neutron Activation Analysis (NAA), ICP-MS, and {gamma}-ray spectrometry, respectively. For the latter, both 1 litre samples (Marinelli-geometry) and 1 cm{sup 3} samples (well-type detectors) were applied in measurements. (author).

  13. A sensitive and quantitative biosensing method for the determination of γ-ray emitting radionuclides in surface water

    International Nuclear Information System (INIS)

    Wolterbeek, H.Th.; Meer, A.J.G.M. van der

    1996-01-01

    A quantitative and sensitive biosensing method has been developed for the determination of γ-ray emitting radionuclides in surface water. The method is based on the concept that at equilibrium the specific radioactivity in the biosensor is equal to the specific radioactivity in water. The method consists of the measurement of both the radionuclide and the element in the biosensor and the determination of the element level in water. This three-way analysis eliminates problems such as unpredictable biosensor behaviour, effects of water elemental composition or further abiotic parameters: what remains is the generally high enrichment (bioaccumulation factor BCF) of elements and radionuclides in the biosensor material. Measurements were performed with floating water plants (Azolla filiculoides Lamk., Spirodela polyrhiza/Lemna sp.) and the fully submerged water plant Ceratophyllum demersum L., which were sampled from ditch water. Concentrations of elements and radionuclides were determined in both water and biosensor plants, using Neutron Activation Analysis (NAA), ICP-MS, and γ-ray spectrometry, respectively. For the latter, both 1 litre samples (Marinelli-geometry) and 1 cm 3 samples (well-type detectors) were applied in measurements. (author)

  14. Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode

    Directory of Open Access Journals (Sweden)

    Yesim Tugce Yaman

    2016-05-01

    Full Text Available A novel electrochemical sensor gold nanoparticle (AuNP/polyvinylpyrrolidone (PVP modified pencil graphite electrode (PGE was developed for the ultrasensitive determination of Bisphenol A (BPA. The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS and scanning electron microscopy (SEM. The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV. Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability.

  15. Fast and sensitive metronidazole determination by means of voltammetry on renewable amalgam silver based electrode without the preconcentration step

    Directory of Open Access Journals (Sweden)

    Piech Robert

    2017-01-01

    Full Text Available Application of cyclic renewable amalgam silver-based electrode (Hg(AgFE for sensitive metronidazole detection by the differential pulse voltammetry (DPV is described. The unique properties of the Hg(AgFE such as the relative large surface area and its fast and very simple renewal were fully utilized for sensitive measurements. Compared with the classical hanging mercury drop electrode (HMDE, the renewable Hg(AgFE significantly increases the reduction peak current of metronidazole because of its large surface area. The effects of various factors for the metronidazole determination such as: pulse height and width, step potential, surface area of the working electrode, and basic electrolyte composition are optimized. The obtained calibration graph is linear from 0.1 (17 μg L-1 to 2 μM (342 μg L-1 with correlation coefficient 0.999. For the Hg(AgFE with the surface area of 10.1 mm2 the limit of detection (LOD is 20 nM (3.4 μg L-1. The repeatability of the method at a concentration of the analyte of 0.5 μM (5.6 μg L−1, expressed as relative standard deviation (RSD is 2.1 % (n = 7. The proposed method was successfully applied and confirmed by studying recovery of metronidazole from spiked samples.

  16. Potentiometric determination of trypsin using a polymeric membrane polycation-sensitive electrode based on current-controlled reagent delivery.

    Science.gov (United States)

    Chen, Yan; Ding, Jiawang; Qin, Wei

    2012-12-01

    A potentiometric biosensor for the determination of trypsin is described based on current-controlled reagent delivery. A polymeric membrane protamine-sensitive electrode with dinonylnaphthalene sulfonate as cation exchanger is used for in situ generation of protamine. Diffusion of protamine across the polymeric membrane can be controlled precisely by applying an external current. The hydrolysis catalyzed with trypsin in sample solution decreases the concentration of free protamine released at the sample-membrane interface and facilitates the stripping of protamine out of the membrane surface via the ion-exchange process with sodium ions from the sample solution, thus decreasing the membrane potential, by which the protease can be sensed potentiometrically. The influences of anodic current amplitude, current pulse duration and protamine concentration in the inner filling solution on the membrane potential response have been studied. Under optimum conditions, the proposed protamine-sensitive electrode is useful for continuous and reversible detection of trypsin over the concentration range of 0.5-5UmL(-1) with a detection limit of 0.3UmL(-1). The proposed detection strategy provides a rapid and reagentless way for the detection of protease activities and offers great potential in the homogeneous immunoassays using proteases as labels. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. The Determination of Feasible Control Variables for Geoengineering and Weather Modification Based on the Theory of Sensitivity in Dynamical Systems

    Directory of Open Access Journals (Sweden)

    Sergei A. Soldatenko

    2016-01-01

    Full Text Available Geophysical cybernetics allows for exploring weather and climate modification (geoengineering as an optimal control problem in which the Earth’s climate system is considered as a control system and the role of controller is given to human operators. In mathematical models used in climate studies control actions that manipulate the weather and climate can be expressed via variations in model parameters that act as controls. In this paper, we propose the “instability-sensitivity” approach that allows for determining feasible control variables in geoengineering. The method is based on the sensitivity analysis of mathematical models that describe various types of natural instability phenomena. The applicability of this technique is illustrated by a model of atmospheric baroclinic instability since this physical mechanism plays a significant role in the general circulation of the atmosphere and, consequently, in climate formation. The growth rate of baroclinic unstable waves is taken as an indicator of control manipulations. The information obtained via calculated sensitivity coefficients is very beneficial for assessing the physical feasibility of methods of control of the large-scale atmospheric dynamics and for designing optimal control systems for climatic processes. It also provides insight into potential future changes in baroclinic waves, as a result of a changing climate.

  18. Green synthesized gold nanoparticles decorated graphene oxide for sensitive determination of chloramphenicol in milk, powdered milk, honey and eye drops.

    Science.gov (United States)

    Karthik, R; Govindasamy, Mani; Chen, Shen-Ming; Mani, Veerappan; Lou, Bih-Show; Devasenathipathy, Rajkumar; Hou, Yu-Shen; Elangovan, A

    2016-08-01

    A simple and rapid green synthesis using Bischofia javanica Blume leaves as reducing agent was developed for the preparation of gold nanoparticles (AuNPs). AuNPs decorated graphene oxide (AuNPs/GO) was prepared and employed for the sensitive amperometric determination of chloramphenicol. The green biosynthesis requires less than 40s to reduce gold salts to AuNPs. The formations of AuNPs and AuNPs/GO were evaluated by scanning electron and atomic force microscopies, UV-Visible and energy dispersive X-ray spectroscopies, X-ray diffraction studies, and electrochemical methods. AuNPs/GO composite film modified electrode was fabricated and shown excellent electrocatalytic ability towards chloramphenicol. Under optimal conditions, the amperometric sensing platform has delivered wide linear range of 1.5-2.95μM, low detection limit of 0.25μM and high sensitivity of 3.81μAμM(-1)cm(-2). The developed sensor exhibited good repeatability and reproducibility, anti-interference ability and long-term storage stability. Practical feasibility of the sensor has been demonstrated in food samples (milk, powdered milk and honey) and pharmaceutical sample (eye drops). The green synthesized AuNPs/GO composite has great potential for analysis of food samples in food safety measures. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Sensitive radioimmunoassay and enzyme-linked immunosorbent assay for the simultaneous determination of chloroquine and its metabolites in biological fluids

    International Nuclear Information System (INIS)

    Escande, C.; Chevalier, P.; Verdier, F.; Bourdon, R.

    1990-01-01

    Two new methods for the simultaneous determination of chloroquine and its two main metabolites (monodesethylchloroquine and bisdesethylchloroquine) in biological samples, radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA), are described. Antiserum is produced in rabbits immunized with N-(2-carboxyethyl)desethylchloroquine:protein conjugate. Besides chloroquine, this antiserum recognizes with good affinity the two main metabolites, monodesethylchloroquine and bisdesethylchloroquine (70 and 40% of crossreaction, respectively). Amodiaquine cross reacts by 4.5%; cross reactions with monodesethylamodiaquine, bisdesethylamodiaquine, and other antimalarial drugs are less than 1%. No extraction step or sample preparation is required for either system. Sensitivity limits are, respectively, 0.70 nM (3 pg of chloroquine sulfate measured in 10 microL of plasma sample) for RIA, and 10 nM (22 pg of chloroquine sulfate measured in 5 microL of plasma sample) for ELISA. The interassay coefficients of variation are, respectively, less than 10 and less than 16% for RIA and ELISA in the range 14-410 nM (6-180 ng/mL). The results of both methods are well correlated (r = 0.97) and correlate with spectrophotometry (r = 0.98) and HPLC results (r = 0.93). Because of their high sensitivity, both methods can be used in the case of chloroquine poisoning and in the control of malaria prophylaxis and treatment

  20. Fluidity of the dietary fatty acid profile and risk of coronary heart disease and ischemic stroke: Results from the EPIC-Netherlands cohort study.

    Science.gov (United States)

    Sluijs, I; Praagman, J; Boer, J M A; Verschuren, W M M; van der Schouw, Y T

    2017-09-01

    The fluidity of dietary fatty acids consumed has been suggested to inversely affect coronary heart disease (CHD) risk. Lipophilic index (LI) represents overall fluidity of the dietary fatty acid profile. Lipophilic load (LL) represents a combination of overall fluidity and absolute intake of dietary fatty acids. We investigated the relations of dietary LI and LL with risk of CHD and ischemic stroke (iStroke). We used data from the prospective EPIC-NL study, including 36,520 participants aged 20-70 years. LI and LL were calculated using dietary intake data estimated with a validated FFQ. Incident CHD (n = 2348) and iStroke (n = 479) cases were obtained through linkage to national registers during 15 years follow-up. LI and LL were not associated with CHD risk (HRs highest-versus-lowest-quartiles : 0.93 [95%CI: 0.83, 1.04], and 0.92 [95%CI: 0.79, 1.07], respectively), and neither with iStroke risk (HRs 1.15 (95%CI: 0.89, 1.48), and 0.98 (95%CI: 0.70, 1.38), respectively). Original fatty acid classes (SFA, MUFA and PUFA), and LI and LL stratified by these fatty acid classes, were overall not related to CHD and ischemic stroke either. In this Dutch population, neither the overall fluidity of the dietary fatty acid profile (LI), nor the combined fluidity and amount of fatty acids consumed (LL) were related to CHD or iStroke risk. Dietary LI and LL may have limited added value above original fatty acid classes and food sources in establishing the relation of fatty acid consumption with CVD. Copyright © 2017 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

  1. Highly sensitive enzymatic determination of urea based on the pH-dependence of the fluorescence of graphene quantum dots

    International Nuclear Information System (INIS)

    Shao, Taili; Zhang, Ping; Zhuo, Shujuan; Zhu, Changqing; Tang, Lin

    2015-01-01

    We report on a nanoparticle-based fluorescent sensing scheme for urea. It is based on the finding that graphene quantum dots (GQDs) display pH-sensitive green fluorescence if photoexcited at 460 nm. Fluorescence is gradually quenched due to an increase in the local pH value as a result of the hydrolysis of urea as catalyzed by urease. The effect was used to quantify urea in the 0.1–100 mM concentration range, with a limit of detection of 0.01 mM. The method was successfully applied to the determination of urea in human serum samples. The method is simple, effective, and therefore holds promise as a platform for sensing urea in blood. (author)

  2. Determination of the interatomic potential from elastic differential cross sections at fixed energy: Functional sensitivity analysis approach

    International Nuclear Information System (INIS)

    Ho, T.; Rabitz, H.

    1989-01-01

    Elastic differential cross sections in atomic crossed beam experiments contain detailed information about the underlying interatomic potentials. The functional sensitivity density of the cross sections with respect to the potential δσ(θ)/δV(R) reveals such information and has been implemented in an iterative inversion procedure, analogous to that of the Newton--Raphson technique. The stability of the inversion is achieved with the use of the regularization method of Tikhonov and Miller. It is shown that given a set of well resolved and noise-free differential cross section data within a limited angular range and given a reasonable starting reference potential, the recovered potential accurately resembles the desired one in the important region, i.e., the region to which the scattering data are sensitive. The region of importance depends upon the collision energy relative to the well depth of the potential under study; usually a higher collision energy penetrates deeper into the repulsive part of the potential and thus accordingly yields a more accurate potential in that part. The inversion procedure produces also a quality function indicating the well determined radial region. Moreover, the extracted potential is quite independent of the functional form of the reference potential in contrast to curve fitting approaches. As illustrations, the model inert gas systems He--Ne and Ne--Ar have been considered. For collision energies within an order of magnitude of the associated potential well depth, the attractive part of the potential can be determined to high precision provided that scattering data at small enough angles are available

  3. Highly sensitive and selective determination of hydrogen sulfide by resonance light scattering technique based on silver nanoparticles.

    Science.gov (United States)

    Kuang, Yangfang; Chen, Shu; Long, Yunfei

    2017-06-01

    We have developed a green approach to prepare DNA-templated silver nanoparticles (Ag-NPs) from the direct reaction between Ag + and ascorbic acid in the presence of DNA and sodium hydroxide. The Ag-NPs showed strong resonance light scattering (RLS) intensity property. Then, the interaction between hydrogen sulfide (H 2 S) and Ag-NPs was studied by measuring their RLS spectra. The results showed that there is a strong interaction between Ag-NPs and H 2 S, which resulted in a decrease in the size of Ag-NPs and a decrease in the RLS intensity of the Ag-NPs solution at the wavelength of 467 nm. The results demonstrated that the RLS technique offers a sensitive and simple tool for investigating the interaction between Ag-NPs and H 2 S, which can be applied to detect H 2 S with high sensitivity and selectivity without complex readout equipment. The linear range for H 2 S determination was found to be the range from 5.0 × 10 -9 to 1.0 × 10 -7  mol L -1 , and the detection limit (3σ/k) was 2.8 × 10 -9  mol L -1 . Moreover, the proposed method was applied for the determination of H 2 S in natural water samples with satisfactory results. Graphical abstract The application of Ag-NPs in H 2 S detection.

  4. Magnetic Beads-Based Sensor with Tailored Sensitivity for Rapid and Single-Step Amperometric Determination of miRNAs

    Directory of Open Access Journals (Sweden)

    Eva Vargas

    2017-11-01

    Full Text Available This work describes a sensitive amperometric magneto-biosensor for single-step and rapid determination of microRNAs (miRNAs. The developed strategy involves the use of direct hybridization of the target miRNA (miRNA-21 with a specific biotinylated DNA probe immobilized on streptavidin-modified magnetic beads (MBs, and labeling of the resulting heteroduplexes with a specific DNA–RNA antibody and the bacterial protein A (ProtA conjugated with an horseradish peroxidase (HRP homopolymer (Poly-HRP40 as an enzymatic label for signal amplification. Amperometric detection is performed upon magnetic capture of the modified MBs onto the working electrode surface of disposable screen-printed carbon electrodes (SPCEs using the H2O2/hydroquinone (HQ system. The magnitude of the cathodic signal obtained at −0.20 V (vs. the Ag pseudo-reference electrode demonstrated linear dependence with the concentration of the synthetic target miRNA over the 1.0 to 100 pM range. The method provided a detection limit (LOD of 10 attomoles (in a 25 μL sample without any target miRNA amplification in just 30 min (once the DNA capture probe-MBs were prepared. This approach shows improved sensitivity compared with that of biosensors constructed with the same anti-DNA–RNA Ab as capture instead of a detector antibody and further labeling with a Strep-HRP conjugate instead of the Poly-HRP40 homopolymer. The developed strategy involves a single step working protocol, as well as the possibility to tailor the sensitivity by enlarging the length of the DNA/miRNA heteroduplexes using additional probes and/or performing the labelling with ProtA conjugated with homopolymers prepared with different numbers of HRP molecules. The practical usefulness was demonstrated by determination of the endogenous levels of the mature target miRNA in 250 ng raw total RNA (RNAt extracted from human mammary epithelial normal (MCF-10A and cancer (MCF-7 cells and tumor tissues.

  5. Highly sensitive determination of hydroxylamine using fused gold nanoparticles immobilized on sol-gel film modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, P. [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Dindigul, Tamilnadu (India); John, S. Abraham, E-mail: abrajohn@yahoo.co.in [Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Dindigul, Tamilnadu (India)

    2010-03-24

    We are reporting the highly sensitive determination of hydroxylamine (HA) using 2-mercapto-4-methyl-5-thiazoleacetic acid (TAA) capped fused spherical gold nanoparticles (AuNPs) modified Au electrode. The fused TAA-AuNPs were immobilized on (3-mercaptopropyl)-trimethoxysilane (MPTS) sol-gel film, which was pre-assembled on Au electrode. The immobilization of fused TAA-AuNPs on MPTS sol-gel film was confirmed by UV-vis absorption spectroscopy and atomic force microscopy (AFM). The AFM image showed that the AuNPs retained the fused spherical morphology after immobilized on sol-gel film. The fused TAA-AuNPs on MPTS modified Au electrode were used for the determination of HA in phosphate buffer (PB) solution (pH = 7.2). When compared to bare Au electrode, the fused AuNPs modified electrode not only shifted the oxidation potential of HA towards less positive potential but also enhanced its oxidation peak current. Further, the oxidation of HA was highly stable at fused AuNPs modified electrode. Using amperometric method, determination of 17.5 nM HA was achieved for the first time. Further, the current response of HA increases linearly while increasing its concentration from 17.5 nM to 22 mM and a detection limit was found to be 0.39 nM (S/N = 3). The present modified electrode was also successfully used for the determination of 17.5 nM HA in the presence of 200-fold excess of common interferents such as urea, NO{sub 2}{sup -}, NH{sub 4}{sup +}, oxalate, Mn{sup 2+}, Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Ba{sup 2+} and Cu{sup 2+}. The practical application of the present modified electrode was demonstrated by measuring the concentration of HA in ground water samples.

  6. Highly sensitive interference-free electrochemical determination of pyridoxine at graphene modified electrode: Importance in Parkinson and Asthma treatments.

    Science.gov (United States)

    Raj, M Amal; Gowthaman, N S K; John, S Abraham

    2016-07-15

    To reduce the side effects in the medication of Parkinson and Asthma, pyridoxine (PY) is administered along with l-3,4-dihydroxyphenyl alanine (l-dopa) and theophylline (TP), respectively. However, excessive dosage of PY leads to nervous disorder. Thus, a sensitive and selective electrochemical method was developed for the determination of PY in the presence of major interferences including TP, l-dopa, ascorbic acid (AA) and riboflavin (RB) using electrochemically reduced graphene oxide (ERGO) film modified glassy carbon electrode (GCE) in this paper. The ERGO fabrication process involves the nucleophilic substitution of graphene oxide at basic pH on amine terminal of 1,6-hexadiamine which was pre-assembled on GCE followed by electrochemical reduction. The electrocatalytic activity of the ERGO modified electrode was examined towards the oxidation of PY. It greatly enhanced the oxidation current of PY in contrast to bare and GO modified GCEs due to facile electron transfer besides π-π interaction between ERGO film and PY. Since TP and l-dopa drugs antagonize the drug action of PY, ERGO modified GCE was also used for the simultaneous determination of PY and l-dopa and PY and TP. Further, the selective determination of PY in the presence of other water soluble vitamins such as ascorbic acid and riboflavin was also demonstrated. Using amperometry, detection of 100nM PY was achieved and the detection limit was found to be 5.6×10(-8)M (S/N=3). The practical application of the present method was demonstrated by determining the concentration of PY in human blood serum and commercial drugs. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Determining the Sensitivity of CAT-ASVAB (Computerized Adaptive Testing- Armed Services Vocational Aptitude Battery) Scores to Changes in Item Response Curves with the Medium of Administration

    Science.gov (United States)

    1986-08-01

    most examinees. Therefore it appears psychometrically ac - ceptable for the CAT -ASVAB project to proceed without item recalibration based on...MEMORANDUM DETERMINING THE SENSITIVITY OF CAT -ASVAB SCORES TO CHANGES IN ITEM RESPONSE CURVES WITH THE MEDIUM OF ADMINISTRATION D. R. Divgi...Subj: Center for Naval Analyses Research Memorandum 86-189 End: (1) CNA Research Memorandum 86-189, "Determining the Sensitivity of CAT -ASVAB

  8. Development of an polarization sensitive Fourier domain optical coherence tomography and it utilization on the Mueller matrix determination

    International Nuclear Information System (INIS)

    Raele, Marcus Paulo

    2009-01-01

    This study approached theoretical and experimental aspects related with the development of a polarization sensitive, Fourier domain, optical coherence tomography system (PS-FD-OCT) and its utilization on the Mueller Matrix determination. This work began with a bibliographic revision, which describes since the early studies to the actual state of the art of the technique. The mathematical formalism of Fourier domain low coherence interferometry and light polarization was performed as well. Studies based on numerical simulations, of three different algorithm types, responsible to recover the scattering profile, were done. The implemented algorithms were: Direct Fourier Transform, Interpolation and zero-filling. By the end of the simulation study, was possible to conclude that the algorithm zero-filling 2N presented better characteristics when compared with the others. In the experimental part, firstly different OCT setups were assembled and measurements were done in order to verify aspects related with the theory. Then, using a polymeric sample, birefringence images were performed, which allowed determining the sample birefringence quantitatively. Finally, images taken of different polarization states were collected, and through then images related with the Mueller Matrix elements were calculated, which were analyzed individually. (author)

  9. Sensitive spectrofluorimetric determination of tizanidine in pharmaceutical preparations, human plasma and urine through derivatization with dansyl chloride.

    Science.gov (United States)

    Ulu, Sevgi Tatar

    2012-01-01

    A sensitive spectrofluorimetric method was developed for the determination of tizanidine in human plasma, urine and pharmaceutical preparations. The method is based on reaction of tizanidine with 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) in an alkaline medium to form a highly fluorescent derivative that was measured at 511 nm after excitation at 383 nm. The different experimental parameters affecting the fluorescence intensity of tizanidine was carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges 50-500 and 20-300 ng/mL for plasma and urine, respectively, detection limits of 1.81 and 0.54 ng/mL and quantification limits of 5.43 and 1.62 ng/mL for plasma and urine, respectively. The method presents good performance in terms of linearity, detection and quantification limits, precision, accuracy and specificity. The proposed method was successfully applied for the determination of tizanidine in pharmaceutical preparations. The results obtained were compared with a reference method, using t- and F-tests. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Accurate determination of interfacial protein secondary structure by combining interfacial-sensitive amide I and amide III spectral signals.

    Science.gov (United States)

    Ye, Shuji; Li, Hongchun; Yang, Weilai; Luo, Yi

    2014-01-29

    Accurate determination of protein structures at the interface is essential to understand the nature of interfacial protein interactions, but it can only be done with a few, very limited experimental methods. Here, we demonstrate for the first time that sum frequency generation vibrational spectroscopy can unambiguously differentiate the interfacial protein secondary structures by combining surface-sensitive amide I and amide III spectral signals. This combination offers a powerful tool to directly distinguish random-coil (disordered) and α-helical structures in proteins. From a systematic study on the interactions between several antimicrobial peptides (including LKα14, mastoparan X, cecropin P1, melittin, and pardaxin) and lipid bilayers, it is found that the spectral profiles of the random-coil and α-helical structures are well separated in the amide III spectra, appearing below and above 1260 cm(-1), respectively. For the peptides with a straight backbone chain, the strength ratio for the peaks of the random-coil and α-helical structures shows a distinct linear relationship with the fraction of the disordered structure deduced from independent NMR experiments reported in the literature. It is revealed that increasing the fraction of negatively charged lipids can induce a conformational change of pardaxin from random-coil to α-helical structures. This experimental protocol can be employed for determining the interfacial protein secondary structures and dynamics in situ and in real time without extraneous labels.

  11. A Simple and Sensitive Plant-Based Western Corn Rootworm Bioassay Method for Resistance Determination and Event Selection.

    Science.gov (United States)

    Wen, Zhimou; Chen, Jeng Shong

    2018-05-26

    We report here a simple and sensitive plant-based western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), bioassay method that allows for examination of multiple parameters for both plants and insects in a single experimental setup within a short duration. For plants, injury to roots can be visually examined, fresh root weight can be measured, and expression of trait protein in plant roots can be analyzed. For insects, in addition to survival, larval growth and development can be evaluated in several aspects including body weight gain, body length, and head capsule width. We demonstrated using the method that eCry3.1Ab-expressing 5307 corn was very effective against western corn rootworm by eliciting high mortality and significantly inhibiting larval growth and development. We also validated that the method allowed determination of resistance in an eCry3.1Ab-resistant western corn rootworm strain. While data presented in this paper demonstrate the usefulness of the method for selection of events of protein traits and for determination of resistance in laboratory populations, we envision that the method can be applied in much broader applications.

  12. Sensitive determination of cadmium using solidified floating organic drop microextraction-slotted quartz tube-flame atomic absorption spectroscopy.

    Science.gov (United States)

    Akkaya, Erhan; Chormey, Dotse Selali; Bakırdere, Sezgin

    2017-09-20

    In this study, solidified floating organic drop microextraction (SFODME) by 1-undecanol was combined with slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) for the determination of cadmium at trace levels. Formation of a complex with 4,4'-dimethyl-2,2'-bipyridine facilitated the extraction of cadmium from aqueous solutions. Several chemical variables were optimized in order to obtain high extraction outputs. Parameters such as concentration of the ligand, pH, and amount of buffer solution were optimized to enhance the formation of cadmium complex. The SFODME method was assisted by dispersion of extractor solvent into aqueous solutions using 2-propanol. Under the optimum extraction and instrumental conditions, the limit of detection and limit of quantitation values obtained for cadmium using the combined methods (SFODME-SQT-FAAS) were found to be 0.4 and 1.3 μg L -1 , respectively. Matrix effects on the method were also examined for tap water and wastewater, and spiked recovery results were found to be very satisfactory. Graphical Abstract SFODME-SQT-FAAS system for sensitive determination of cadmium.

  13. Electrochemical sensor based on a carbon nanotube-modified imprinted sol–gel for selective and sensitive determination of β2-agonists

    International Nuclear Information System (INIS)

    Xu, Wei; Liu, Ping; Guo, Chunhui; Dong, Chao; Zhang, Xiuhua; Wang, Shengfu

    2013-01-01

    We describe a molecularly imprinted electrochemical sensor for selective and sensitive determination of β2-agonists. It is making use of a combination of single-wall carbon nanotubes (SWNTs) with a molecularly imprinted sol–gel. The SWNTs were introduced in order to enhance electron transport and sensitivity. The imprinted sol–gel film with its specific binding sites acts as a selective recognition element and as a preconcentrator for β 2 -agonists. The morphology of the imprinted film was characterized by scanning electron microscopy. The optimized sensor displays high sensitivity and excellent selectivity for the β 2 -agonists as shown for their determination in human serum samples. (author)

  14. Determination of the topology of endoplasmic reticulum membrane proteins using redox-sensitive green-fluorescence protein fusions.

    Science.gov (United States)

    Tsachaki, Maria; Birk, Julia; Egert, Aurélie; Odermatt, Alex

    2015-07-01

    Membrane proteins of the endoplasmic reticulum (ER) are involved in a wide array of essential cellular functions. Identification of the topology of membrane proteins can provide significant insight into their mechanisms of action and biological roles. This is particularly important for membrane enzymes, since their topology determines the subcellular site where a biochemical reaction takes place and the dependence on luminal or cytosolic co-factor pools and substrates. The methods currently available for the determination of topology of proteins are rather laborious and require post-lysis or post-fixation manipulation of cells. In this work, we have developed a simple method for defining intracellular localization and topology of ER membrane proteins in living cells, based on the fusion of the respective protein with redox-sensitive green-fluorescent protein (roGFP). We validated the method and demonstrated that roGFP fusion proteins constitute a reliable tool for the study of ER membrane protein topology, using as control microsomal 11β-hydroxysteroid dehydrogenase (11β-HSD) proteins whose topology has been resolved, and comparing with an independent approach. We then implemented this method to determine the membrane topology of six microsomal members of the 17β-hydroxysteroid dehydrogenase (17β-HSD) family. The results revealed a luminal orientation of the catalytic site for three enzymes, i.e. 17β-HSD6, 7 and 12. Knowledge of the intracellular location of the catalytic site of these enzymes will enable future studies on their biological functions and on the role of the luminal co-factor pool. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Spectrophotometric and chromatographic determination of insensitive energetic materials: HNS and NTO, in the presence of sensitive nitro-explosives.

    Science.gov (United States)

    Can, Ziya; Uzer, Ayşem; Tekdemir, Yasemin; Erçağ, Erol; Türker, Lemi; Apak, Reşat

    2012-02-15

    As there are no molecular spectroscopic determination methods for the most widely used insensitive energetic materials, 2,2',4,4',6,6'-hexanitrostilbene (HNS) and 3-nitro-1,2,4-triazole-5-one (NTO), in the presence of sensitive nitro-explosives, two novel spectrophotometric methods were developed. For HNS and TNT mixtures, both analytes react with dicyclohexylamine (DCHA) forming different colored charge-transfer complexes, which can be resolved by derivative spectroscopy. The spectrophotometric method for NTO measures the 416-nm absorbance of its yellow-colored Na(+)NTO(-) salt formed with NaOH. TNT, if present, is pre-extracted into IBMK as its Meisenheimer anion forming an ion-pair with the cationic surfactant cetyl pyridinium (CP(+)) in alkaline medium, whereas the unextracted NTO is determined in the aqueous phase. The molar absorptivity (ε, L mol(-1)cm(-1)) and limit of quantification (LOQ, mg L(-1)) are as follows: for HNS, ε=2.75 × 10(4) and LOQ=0.48 (in admixture with TNT); for NTO, ε=6.83 × 10(3) and LOQ=0.73. These methods were not affected from nitramines and nitrate esters in synthetic mixtures or composite explosives. The developed methods were statistically validated against HPLC, and the existing chromatographic method was modified so as to enable NTO determination in the presence of TNT. These simple, low-cost, and versatile methods can be used in criminology, remediation/monitoring of contaminated sites, and kinetic stability modeling of munitions containing desensitized energetic materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Environmental determinants of the spatial distribution of Mesocestoides spp. and sensitivity of flotation method for the diagnosis of mesocestoidosis.

    Science.gov (United States)

    Széll, Z; Tolnai, Z; Sréter, T

    2015-09-15

    Mesocestoides spp. are zoonotic cestodes of wild and domesticated carnivores. Although the adult stages are relatively harmless intestinal parasites, the metacestode stages (tetrathyridia) can be responsible for life-threatening peritonitis and pleuritis in several species including dogs, cats, non-human primates and probably man. The aim of the present study was to reveal the spatial distribution pattern of Mesocestoides spp. in the most important final hosts, red foxes (Vulpes vulpes), to analyse the relationship of these patterns with landscape and climate by geographical information systems and to evaluate faecal flotation method for the detection of infection in the final host. Fox carcasses, representing 0.5% of the total fox population were randomly selected out of all the foxes of Hungary. The intestinal tract was examined by sedimentation and counting technique. The sensitivity of the flotation method was evaluated by the testing of the faecal samples of 180 foxes infected with Mesocestoides spp. The prevalence of infection was high in foxes (45.8%; 95% CI=41.0-50.6%), and the parasite was detected in all areas of Hungary. The high prevalence of the parasite in foxes suggests that the infection might also be common in outdoor dogs and cats. Mesocestoides infection could not be detected in any of the foxes by flotation method indicating that the sensitivity of the method is less than 0.6%. Therefore, almost all canine and feline infections remain undetected in the veterinary practice. Based on the statistical analysis, the altitude was the only determinant of the spatial distribution of Mesocestoides spp. indicating that infections in carnivores including dogs and cats can be expected mainly in midland regions (150-750 m above sea level). It might be attributed to the altitude-dependent species richness and abundance of the intermediate and final hosts of the parasite. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Role of glutathione in determining the differential sensitivity between the cortical and cerebellar regions towards mercury-induced oxidative stress

    International Nuclear Information System (INIS)

    Kaur, Parvinder; Aschner, Michael; Syversen, Tore

    2007-01-01

    Certain discrete areas of the CNS exhibit enhanced sensitivity towards MeHg. To determine whether GSH is responsible for this particular sensitivity, we investigated its role in MeHg-induced oxidative insult in primary neuronal and astroglial cell cultures of both cerebellar and cortical origins. For this purpose, ROS and GSH were measured with the fluorescent indicators, CMH 2 DCFDA and MCB. Cell associated-MeHg was measured with 14 C-radiolabeled MeHg. The intracellular GSH content was modified by pretreatment with NAC or DEM. For each of the dependent variables (ROS, GSH, and MTT), there was an overall significant effect of cellular origin, MeHg and pretreatment in all the cell cultures. A trend towards significant interaction between origin x MeHg x pretreatment was observed only for the dependent variable, ROS (astrocytes p = 0.056; neurons p = 0.000). For GSH, a significant interaction between origin x MeHg was observed only in astrocytes (p = 0.030). The cerebellar cell cultures were more vulnerable (astrocytes mean = 223.77; neurons mean = 138.06) to ROS than the cortical cell cultures (astrocytes mean = 125.18; neurons mean 107.91) for each of the tested treatments. The cell associated-MeHg increased when treated with DEM, and the cerebellar cultures varied significantly from the cortical cultures. Non-significant interactions between origin x MeHg x pretreatment for GSH did not explain the significant interactions responsible for the increased amount of ROS produced in these cultures. In summary, although GSH modulation influences MeHg-induced toxicity, the difference in the content of GSH in cortical and cerebellar cultures fails to account for the increased ROS production in cerebellar cultures. Hence, different approaches for the future studies regarding the mechanisms behind selectivity of MeHg have been discussed

  18. Apple allergy across Europe: how allergen sensitization profiles determine the clinical expression of allergies to plant foods

    NARCIS (Netherlands)

    Fernández-Rivas, Montserrat; Bolhaar, Suzanne; González-Mancebo, Eloina; Asero, Riccardo; van Leeuwen, Astrid; Bohle, Barbara; Ma, Yan; Ebner, Christof; Rigby, Neil; Sancho, Ana I.; Miles, Susan; Zuidmeer, Laurian; Knulst, André; Breiteneder, Heimo; Mills, Clare; Hoffmann-Sommergruber, Karin; van Ree, Ronald

    2006-01-01

    BACKGROUND: Allergy to a plant food can either result from direct sensitization to that food or from primary sensitization to pollen, latex, or another food. OBJECTIVE: We sought to investigate the primary sensitizers in apple allergy across Europe, the individual allergens involved, and whether

  19. Determinants and prognostic implications of Cardiac Troponin T measured by a sensitive assay in Type 2 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Hallén Jonas

    2010-09-01

    Full Text Available Abstract Background The cardiac troponins are biomarkers used for diagnosis of myocardial injury. They are also powerful prognostic markers in many diseases and settings. Recently introduced high-sensitivity assays indicate that chronic cardiac troponin elevations are common in response to cardiovascular (CV morbidity. Type 2 diabetes mellitus (T2DM confers a high risk of CV disease, but little is known about chronic cardiac troponin elevations in diabetic subjects. Accordingly, we aimed to understand the prevalence, determinants, and prognostic implications of cardiac troponin T (cTnT elevations measured with a high-sensitivity assay in patients with T2DM. Methods cTnT was measured in stored, frozen serum samples from 124 subjects enrolled in the Asker and Bærum Cardiovascular Diabetes trial at baseline and at 2-year follow-up, if availabe (96 samples available. Results were analyzed in relation to baseline variables, hospitalizations, and group assignment (multifactorial intensive versus conventional diabetes care for lowering CV risk. Results One-hundred thirteen (90 % had detectable cTnT at baseline and of those, 22 (18 % of the total population subjects had values above the 99th percentile for healthy controls (13.5 ng/L. Levels at baseline were associated with conventional CV risk factors (age, renal function, gender. There was a strong correlation between cTnT levels at the two time-points (r = 0.92, p > 0.001. Risk for hospitalizations during follow-up increased step-wise by quartiles of hscTnT measured at baseline (p = 0.058. Conclusions Elevations of cTnT above the 99th percentile measured by a highly sensitive assay were encountered frequently in a population of T2DM patients. cTnT levels appeared to be stable over time and associated with conventional CV risk factors. Although a clear trend was present, no statistically robust associations with adverse outcomes could be found.

  20. Determination of organophosphorus pesticides in water samples by using a new sensitive luminescent probe of Eu (III) complex

    Energy Technology Data Exchange (ETDEWEB)

    Azab, Hassan A., E-mail: azab2@yahoo.com; Anwar, Z.M.; Rizk, M.A.; Khairy, Gasser M.; El-Asfoury, M.H.

    2015-01-15

    , Endosulfan, and Heptachlor were used. • A sensitive rapid, cheap direct method for the determination of the pesticides has been developed. • The method was applied to the determination of the organophosphorus pesticides in tap, river, and waste water.

  1. Determination of organophosphorus pesticides in water samples by using a new sensitive luminescent probe of Eu (III) complex

    International Nuclear Information System (INIS)

    Azab, Hassan A.; Anwar, Z.M.; Rizk, M.A.; Khairy, Gasser M.; El-Asfoury, M.H.

    2015-01-01

    Heptachlor were used. • A sensitive rapid, cheap direct method for the determination of the pesticides has been developed. • The method was applied to the determination of the organophosphorus pesticides in tap, river, and waste water

  2. FLUIDITY SPEECH FORMATION AS A QUALITATIVE CHARACTERISTIC OF THE ORAL STATEMENT OF PRESCHOOL AGE CHILDREN WITH STUTTER

    Directory of Open Access Journals (Sweden)

    E. A. Borisova

    2014-01-01

    Full Text Available The research objective is to disclose the subject matter of speech therapy work focused on fluidity speech formation of preschool age children, suffering stutter. Stutter is a difficult disorder of articulation organs suchthat the tempo-rhythmical organisation of statements is distressed that leads to defects and failures of dialogue system, negatively influences on individual development of the child; more specifically it generates the mental stratifications, specific features of emotional-volitional sphere, and causes undesirable qualities ofcharacter such as shyness, indecision, isolation, negativism. The author notes that the problem of early stutter correction among junior preschool-aged children considered as topical and immediate issue. Methods. Concerning the clinical, physiological, psychological and psychologic-pedagogical positions, the author summarizes theoretical framework; an experimentally-practical approbation of an author's method of speech fluidity and stutter abolition of preschool children is described. Stage-by-stage process of correction,spontaneous and non-convulsive speech formation: 1. restraint mode application in order to decrease incorrect verbal output; 2. training exercises to long phonatory and speech expiration; 3. development of coordination and movements rhythm helping to pronounce words and phrases; 4. formation of situational speech, at first consisted of short sentences, then passing to long ones; 5. training to coherent text statements. The research demonstrates data analyses of postexperimental diagnostic examination of stuttering preschool children, proving the efficiency of the author’s applied method. Scientific novelty. The research findings demonstrate a specific approach to correction and stutter abolition of preschool children. Proposed author’s approach consists of complementary to each other directions of speech therapy work which are combines in the following way: coherent speech

  3. Comparison between sensitivity of a viscometric method and sensitivity of the alkaline elution assay for the determination of DNA damage induced by dimethylsulfate in vitro.

    Science.gov (United States)

    Parodi, S; Balbi, C; Taningher, M; Abelmoschi, M L; Pala, M; Parodi, G; Santi, L

    1982-03-01

    DNA damage induced by dimethylsulfate (DMS) was measured with a new oscillating crucible viscometer, having a U-shaped circular channel. Rat liver nuclei were treated in vitro. Viscosity was measured by lysing nuclei in an aklaline lysing solution (pH 12.5; 25 degrees C). Nuclei were lysed immediately in the viscometer and released DNA started to uncoil. In control samples the viscosity increased very slowly with time, reaching a maximum only after about 8 h. A progressively more rapid increase in viscosity was seen with increasing concentrations of DMS. The time of DNA disentanglement was sensitive to about 30 times less breaks than the alkaline elution assay.

  4. A sensitive molecularly imprinted polymer based quartz crystal microbalance nanosensor for selective determination of lovastatin in red yeast rice.

    Science.gov (United States)

    Eren, Tanju; Atar, Necip; Yola, Mehmet Lütfi; Karimi-Maleh, Hassan

    2015-10-15

    Lovastatin (LOV) is a statin, used to lower cholesterol which has been found as a hypolipidemic agent in commercial red yeast rice. In present study, a sensitive molecular imprinted quartz crystal microbalance (QCM) sensor was prepared by fabricating a self-assembling monolayer formation of allylmercaptane on QCM chip surface for selective determination of lovastatin (LOV) in red yeast rice. To prepare molecular imprinted quartz crystal microbalance (QCM) nanosensor, LOV imprinted poly(2-hydroxyethyl methacrylate-methacryloylamidoaspartic acid) [p(HEMA-MAAsp)] nanofilm was attached on the modified gold surface of QCM chip. The non-modified and improved surfaces were characterized by using contact angle, atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. The imprinted QCM sensor was validated according to the ICH guideline (International Conference on Harmonisation). The linearity range was obtained as 0.10-1.25 nM. The detection limit of the prepared material was calculated as 0.030 nM. The developed QCM nanosensor was successfully used to examine red yeast rice. Furthermore, the stability and repeatability of the prepared QCM nanosensor were studied. The spectacular long-term stability and repeatability of the prepared LOV-imprinted QCM nanosensor make them intriguing for use in QCM sensors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Multianalyte, high-throughput liquid chromatography tandem mass spectrometry method for the sensitive determination of fungicides and insecticides in wine.

    Science.gov (United States)

    Castro, Gabriela; Pérez-Mayán, Leticia; Rodríguez-Cabo, Tamara; Rodríguez, Isaac; Ramil, Maria; Cela, Rafael

    2018-01-01

    Evidence of pesticide transfer from grapes to wine, added to differences in the national regulations regarding the number and the maximum concentration of these species in wine, demands analytical procedures suitable for their routine control in this foodstuff. In this research, solid-phase extraction (SPE) and ultra-performance liquid chromatography (UPLC), with tandem mass spectrometry (MS/MS) detection, are combined to obtain a sensitive and rapid procedure to determine 50 pesticides in red and white wines. Efficiency and selectivity of sample preparation are correlated with the type of sorbent, the elution solvent, and the physicochemical properties of pesticides. SPE of 2-mL wine samples followed by direct injection of the extract in the UPLC-MS/MS system provides quantification limits (LOQs) below 1 ng mL -1 for 48 out of 50 compounds, linear responses up to 200 ng mL -1 , and acceptable accuracy, employing quantification against solvent-based standards, for 45 species. A total analysis time of 10 min, including compounds separation and re-equilibration of the UPLC column, was achieved. The developed methodology was applied to 25 wines (20 conventional and 5 ecological), produced in 7 different countries. Out of 27 pesticides quantified in these wines, 12 displayed occurrence frequencies above 24%; moreover, all wines, except one of the ecological ones, contained residues from at least one pesticide.

  6. Rapid and Sensitive Determination of Timosaponin AIII in Rat Plasma by LC-MS/MS and Its Pharmacokinetic Application

    Directory of Open Access Journals (Sweden)

    Zhenzhen Cai

    2013-02-01

    Full Text Available A rapid sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS method was developed for determination of timosaponin AIII (TA-III in rat plasma, using ginsenoside Re as an internal standard (IS. TA-III and the IS were detected in MRM mode with a negative ionization electrospray mass spectrometer. The calibration curves were linear over the concentration ranges from 11.14 to 1114 ng/mL and the lower limit of quantification (LLOQ was 11.14 ng/mL. Intra-day and inter-day precisions (RSD were within 10%, and accuracy ranged from 6.4% to 9.1%. The extraction recovery at three concentrations ranged from 92.3% to 95.5%. The validated method was successfully applied to monitor the concentrations of TA-III in rat plasma after intragastric administration. The best fit pharmacokinetic model to estimate the pharmacokinetic parameters was a single compartment model with weight of 1/x2 for oral administration groups of rats for TA-III.

  7. Co-stimulatory signaling determines tumor antigen sensitivity and persistence of CAR T cells targeting PSCA+ metastatic prostate cancer.

    Science.gov (United States)

    Priceman, Saul J; Gerdts, Ethan A; Tilakawardane, Dileshni; Kennewick, Kelly T; Murad, John P; Park, Anthony K; Jeang, Brook; Yamaguchi, Yukiko; Yang, Xin; Urak, Ryan; Weng, Lihong; Chang, Wen-Chung; Wright, Sarah; Pal, Sumanta; Reiter, Robert E; Wu, Anna M; Brown, Christine E; Forman, Stephen J

    2018-01-01

    Advancing chimeric antigen receptor (CAR)-engineered adoptive T cells for the treatment of solid cancers is a major focus in the field of immunotherapy, given impressive recent clinical responses in hematological malignancies. Prostate cancer may be amenable to T cell-based immunotherapy since several tumor antigens, including prostate stem-cell antigen (PSCA), are widely over-expressed in metastatic disease. While antigen selectivity of CARs for solid cancers is crucial, it is problematic due to the absence of truly restricted tumor antigen expression and potential safety concerns with "on-target off-tumor" activity. Here, we show that the intracellular co-stimulatory signaling domain can determine a CAR's sensitivity for tumor antigen expression. A 4-1BB intracellular co-stimulatory signaling domain in PSCA-CARs confers improved selectivity for higher tumor antigen density, reduced T cell exhaustion phenotype, and equivalent tumor killing ability compared to PSCA-CARs containing the CD28 co-stimulatory signaling domain. PSCA-CARs exhibit robust in vivo anti-tumor activity in patient-derived bone-metastatic prostate cancer xenograft models, and 4-1BB-containing CARs show superior T cell persistence and control of disease compared with CD28-containing CARs. Our study demonstrates the importance of co-stimulation in defining an optimal CAR T cell, and also highlights the significance of clinically relevant models in developing solid cancer CAR T cell therapies.

  8. Small protease sensitive oligomers of PrPSc in distinct human prions determine conversion rate of PrP(C.

    Directory of Open Access Journals (Sweden)

    Chae Kim

    Full Text Available The mammalian prions replicate by converting cellular prion protein (PrP(C into pathogenic conformational isoform (PrP(Sc. Variations in prions, which cause different disease phenotypes, are referred to as strains. The mechanism of high-fidelity replication of prion strains in the absence of nucleic acid remains unsolved. We investigated the impact of different conformational characteristics of PrP(Sc on conversion of PrP(C in vitro using PrP(Sc seeds from the most frequent human prion disease worldwide, the Creutzfeldt-Jakob disease (sCJD. The conversion potency of a broad spectrum of distinct sCJD prions was governed by the level, conformation, and stability of small oligomers of the protease-sensitive (s PrP(Sc. The smallest most potent prions present in sCJD brains were composed only of∼20 monomers of PrP(Sc. The tight correlation between conversion potency of small oligomers of human sPrP(Sc observed in vitro and duration of the disease suggests that sPrP(Sc conformers are an important determinant of prion strain characteristics that control the progression rate of the disease.

  9. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    Science.gov (United States)

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-02-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

  10. Hepatitis C virus and the controversial role of the interferon sensitivity determining region in the response to interferon treatment.

    Science.gov (United States)

    Torres-Puente, Manuela; Cuevas, José M; Jiménez-Hernández, Nuria; Bracho, María A; García-Robles, Inmaculada; Carnicer, Fernando; del Olmo, Juan; Ortega, Enrique; Moya, Andrés; González-Candelas, Fernando

    2008-02-01

    The degree of variability of the interferon sensitivity determining region (ISDR) in the hepatitis C virus (HCV) genome has been postulated to predict the response to interferon therapy, mainly in patients infected with subtype 1b, although this prediction has been the subject of a long controversy. This prediction has been tested by analyzing a cohort of 67 Spanish patients infected with HCV genotype 1, 23 of which were infected with subtype 1a and 44 with subtype 1b. A sample previous to therapy with alpha-interferon plus ribavirin was obtained and several clones (between 25 and 96) including the ISDR were sequenced from each patient. A significant correlation between mutations at the ISDR and response to treatment for subtype 1b patients, but not for those infected with subtype 1a, has been detected. Although the results suggest that the same relationship holds true for subtype 1a, lack of statistical power because of the small sample size of this subtype prevented firmer conclusions. However, identical ISDR sequences were found in responder and non-responder patients, suggesting that the stability of the ISDR sequence can occasionally help HCV to evade interferon therapy, although this is not a sufficient condition. More complex interactions, including the ISDR or not, are likely to exist and govern the HCV response to interferon treatment. (Copyright) 2007 Wiley-Liss, Inc.

  11. Sensitive and selective determination of Cu2+ at D-penicillamine functionalized nano-cellulose modified pencil graphite electrode

    Science.gov (United States)

    Taheri, M.; Ahour, F.; Keshipour, S.

    2018-06-01

    A novel electrochemical sensor based on D-penicillamine anchored nano-cellulose (DPA-NC) modified pencil graphite electrode was fabricated and used for highly selective and sensitive determination of copper (II) ions in the picomolar concentration by square wave adsorptive stripping voltammetric (SWV) method. The modified electrode showed better and increased SWV response compared to the bare and NC modified electrodes which may be related to the porous structure of modifier along with formation of complex between Cu2+ ions and nitrogen or oxygen containing groups in DPA-NC. Optimization of various experimental parameters influence the performance of the sensor, were investigated. Under optimized condition, DPA-NC modified electrode was used for the analysis of Cu2+ in the concentration range from 0.2 to 50 pM, and a lower detection limit of 0.048 pM with good stability, repeatability, and selectivity. Finally, the practical applicability of DPA-NC-PGE was confirmed via measuring trace amount of Cu (II) in tap and river water samples.

  12. Co-stimulatory signaling determines tumor antigen sensitivity and persistence of CAR T cells targeting PSCA+ metastatic prostate cancer

    Science.gov (United States)

    Priceman, Saul J.; Gerdts, Ethan A.; Tilakawardane, Dileshni; Kennewick, Kelly T.; Murad, John P.; Park, Anthony K.; Jeang, Brook; Yamaguchi, Yukiko; Urak, Ryan; Weng, Lihong; Chang, Wen-Chung; Wright, Sarah; Pal, Sumanta; Reiter, Robert E.; Brown, Christine E.; Forman, Stephen J.

    2018-01-01

    ABSTRACT Advancing chimeric antigen receptor (CAR)-engineered adoptive T cells for the treatment of solid cancers is a major focus in the field of immunotherapy, given impressive recent clinical responses in hematological malignancies. Prostate cancer may be amenable to T cell-based immunotherapy since several tumor antigens, including prostate stem-cell antigen (PSCA), are widely over-expressed in metastatic disease. While antigen selectivity of CARs for solid cancers is crucial, it is problematic due to the absence of truly restricted tumor antigen expression and potential safety concerns with “on-target off-tumor” activity. Here, we show that the intracellular co-stimulatory signaling domain can determine a CAR's sensitivity for tumor antigen expression. A 4-1BB intracellular co-stimulatory signaling domain in PSCA-CARs confers improved selectivity for higher tumor antigen density, reduced T cell exhaustion phenotype, and equivalent tumor killing ability compared to PSCA-CARs containing the CD28 co-stimulatory signaling domain. PSCA-CARs exhibit robust in vivo anti-tumor activity in patient-derived bone-metastatic prostate cancer xenograft models, and 4-1BB-containing CARs show superior T cell persistence and control of disease compared with CD28-containing CARs. Our study demonstrates the importance of co-stimulation in defining an optimal CAR T cell, and also highlights the significance of clinically relevant models in developing solid cancer CAR T cell therapies. PMID:29308300

  13. Determination of ABO blood grouping from human oral squamous epithelium by the highly sensitive immunohistochemical staining method EnVision+.

    Science.gov (United States)

    Noda, Hiroshi; Yokota, Makoto; Tatsumi, Shinji; Sugiyama, Shizuyuki

    2002-03-01

    Using the highly sensitive immunohistochemical staining method EnVision+, which employs a dextran polymer reagent for the secondary antibody, the detection of the ABH antigens was attempted in the oral squamous epithelium. This new technique uses monoclonal antibody as a primary antibody and it takes about three hours for staining. The time is much shorter than conventional absorption-elution testing or absorption-inhibition testing for the determination of ABO blood grouping. Secretor saliva samples were stained at strong intensity by the antibody, which corresponded to its blood group and anti-H. On the one hand, nonsecretor saliva samples were stained at strong intensity only by the antibody that corresponded to its blood group, and at weak intensity only by anti-H. Since human oral squamous epithelium antigens were stained specifically by this method, we can examine the ABO blood group of saliva samples and perform cytodiagnosis at the same time. Our research suggested that the EnVision+ Method is a useful technique for ABO blood grouping of saliva in forensic cases.

  14. [Weight parameters of water quality impact and risk grade determination of water environmental sensitive spots in Jiashan].

    Science.gov (United States)

    Xie, Rong-Rong; Pang, Yong; Zhang, Qian; Chen, Ke; Sun, Ming-Yuan

    2012-07-01

    For the safety of the water environment in Jiashan county in Zhejiang Province, one-dimensional hydrodynamic and water quality models are established based on three large-scale monitoring of hydrology and water quality in Jiashan county, three water environmental sensitive spots including Hongqitang dam Chijia hydrological station and Luxie pond are selected to investigate weight parameters of water quality impact and risk grade determination. Results indicate as follows (1) Internal pollution impact in Jiashan areas was greater than the external, the average weight parameters of internal chemical oxygen demand (COD) pollution is 55.3%, internal ammonia nitrogen (NH(4+)-N) is 67.4%, internal total phosphor (TP) is 63.1%. Non-point pollution impact in Jiashan areas was greater than point pollution impact, the average weight parameters of non-point COD pollutions is 53.7%, non-point NH(4+)-N is 65.9%, non-point TP is 57.8%. (2) The risk of Hongqitang dam and Chijia hydrological station are in the middle risk. The risk of Luxie pond is also in the middle risk in August, and in April and December the risk of Luxie pond is low. The strategic decision will be suggested to guarantee water environment security and social and economic security in the study.

  15. IgE Sensitization Patterns to Commonly Consumed Foods Determined by Skin Prick Test in Korean Adults

    OpenAIRE

    Kim, Sung Ryeol; Park, Hye Jung; Park, Kyung Hee; Lee, Jae-Hyun; Park, Jung-Won

    2016-01-01

    Offending food allergens can vary with regional preferences in food consumption. In this study, we analysed sensitization rates to commonly consumed foods in Korean adults suspected of having food allergy. One hundred and thirty four subjects underwent a skin prick test (SPT) with 55 food allergens, of which 13 were made by our laboratory and the rest were commercially purchased. Of the 134 patients, 73 (54.5%) were sensitized to one or more food allergens. Sensitization to chrysalis was dete...

  16. Endocrine determinants of changes in insulin sensitivity and insulin secretion during a weight cycle in healthy men.

    Directory of Open Access Journals (Sweden)

    Judith Karschin

    Full Text Available Changes in insulin sensitivity (IS and insulin secretion occur with perturbations in energy balance and glycemic load (GL of the diet that may precede the development of insulin resistance and hyperinsulinemia. Determinants of changes in IS and insulin secretion with weight cycling in non-obese healthy subjects remain unclear.In a 6wk controlled 2-stage randomized dietary intervention 32 healthy men (26±4y, BMI: 24±2kg/m2 followed 1wk of overfeeding (OF, 3wks of caloric restriction (CR containing either 50% or 65% carbohydrate (CHO and 2wks of refeeding (RF with the same amount of CHO but either low or high glycaemic index at ±50% energy requirement. Measures of IS (basal: HOMA-index, postprandial: Matsuda-ISI, insulin secretion (early: Stumvoll-index, total: tAUC-insulin/tAUC-glucose and potential endocrine determinants (ghrelin, leptin, adiponectin, thyroid hormone levels, 24h-urinary catecholamine excretion were assessed.IS improved and insulin secretion decreased due to CR and normalized upon RF. Weight loss-induced improvements in basal and postprandial IS were associated with decreases in leptin and increases in ghrelin levels, respectively (r = 0.36 and r = 0.62, p<0.05. Weight regain-induced decrease in postprandial IS correlated with increases in adiponectin, fT3, TSH, GL of the diet and a decrease in ghrelin levels (r-values between -0.40 and 0.83, p<0.05 whereas increases in early and total insulin secretion were associated with a decrease in leptin/adiponectin-ratio (r = -0.52 and r = -0.46, p<0.05 and a decrease in fT4 (r = -0.38, p<0.05 for total insulin secretion only. After controlling for GL associations between RF-induced decrease in postprandial IS and increases in fT3 and TSH levels were no longer significant.Weight cycling induced changes in IS and insulin secretion were associated with changes in all measured hormones, except for catecholamine excretion. While leptin, adiponectin and ghrelin seem to be the major

  17. A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles

    International Nuclear Information System (INIS)

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-01-01

    An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO_2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770 mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660 mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO_2. The ZrO_2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645 mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO_2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10–160 nM yielding a detection limit of 2.25 nM (based on 3S_b/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO_2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use. - Graphical abstract: A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles. Display Omitted - Highlights: • A composite electrode was prepared using nanoparticles of ZrO_2 and MWCNTs. • The ZrO_2NPs/MWCNTs/GCE has greatly improved the voltammetry of terbutaline • The proposed electrode enabled a detection limit of 2.25 nM. • The proposed electrode exhibited good reproducibility and long

  18. Variations in daily intakes of myristic and alpha-linolenic acids in sn-2 position modify lipid profile and red blood cell membrane fluidity.

    Science.gov (United States)

    Dabadie, Henry; Motta, Claude; Peuchant, Evelyne; LeRuyet, Pascale; Mendy, François

    2006-08-01

    The present study evaluated the effects of moderate intakes of myristic acid (MA), at 1.2% and 1.8% of total energy (TE), associated with a 0.9% TE intake of alpha-linolenic acid (ALA) on lipid and fatty acid profiles and red blood cell membrane fluidity. Twenty-nine monks without dyslipidaemia were enrolled in a 1-year nutritional study in which two experimental diets were tested for 3 months each: diet 1, MA 1.2 % and ALA 0.9%; diet 2, MA 1.8% and ALA 0.9%. A control diet (MA 1.2%, ALA 0.4%) was given 3 months before diets 1 and 2. Thus, two different levels of MA (1.2%, 1.8%) and ALA (0.4%, 0.9%) were tested. Intakes of other fatty acids were at recommended levels. Samples were obtained on completion of all three diets. For fluidity analysis, the red blood cells were labelled with 16-doxylstearate and the probe incorporated the membrane where relaxation-correlation time was calculated. Diet 1 was associated with a decrease in total cholesterol, in LDL-cholesterol, in triacylglycerols and in the ratio of total to HDL-cholesterol; ALA and EPA levels were increased in both phospholipids and cholesterol esters. Diet 2 was associated with a decrease in triacylglycerols and in the ratios of total to HDL-cholesterol and of triacylglycerols to HDL-cholesterol, and with an increase in HDL-cholesterol; EPA levels were decreased in phospholipids and cholesterol esters. Red blood cell membrane fluidity was increased in both diets (Pdiet 1, mainly in the oldest subjects. Intakes of myristic acid (1.2%TE) and ALA (0.9%TE), both mainly in the sn-2 position, were associated with favourable lipid and n-3 long-chain fatty acid profiles. These beneficial effects coexisted with particularly high membrane fluidity, especially among the oldest subjects.

  19. Combination of 1H nuclear magnetic resonance spectroscopy and principal component analysis to evaluate the lipid fluidity of flutamide-encapsulated lipid nanoemulsions.

    Science.gov (United States)

    Takegami, Shigehiko; Ueyama, Keita; Konishi, Atsuko; Kitade, Tatsuya

    2018-06-06

    The lipid fluidity of various lipid nanoemulsions (LNEs) without and with flutamide (FT) and containing one of two neutral lipids, one of four phosphatidylcholines as a surfactant, and sodium palmitate as a cosurfactant was investigated by the combination of 1 H nuclear magnetic resonance (NMR) spectroscopy and principal component analysis (PCA). In the 1 H NMR spectra, the peaks from the methylene groups of the neutral lipids and surfactants for all LNE preparations showed downfield shifts with increasing temperature from 20 to 60 °C. PCA was applied to the 1 H NMR spectral data obtained for the LNEs. The PCA resulted in a model in which the first two principal components (PCs) extracted 88% of the total spectral variation; the first PC (PC-1) axis and second PC (PC-2) axis accounted for 73 and 15%, respectively, of the total spectral variation. The Score-1 values for PC-1 plotted against temperature revealed the existence of two clusters, which were defined by the neutral lipid of the LNE preparations. Meanwhile, the Score-2 values decreased with rising temperature and reflected the increase in lipid fluidity of each LNE preparation, consistent with fluorescence anisotropy measurements. In addition, the changes of Score-2 values with temperature for LNE preparations with FT were smaller than those for LNE preparations without FT. This indicates that FT encapsulated in LNE particles markedly suppressed the increase in lipid fluidity of LNE particles with rising temperature. Thus, PCA of 1 H NMR spectra will become a powerful tool to analyze the lipid fluidity of lipid nanoparticles. Graphical abstract ᅟ.

  20. What determines the sensitivity of the real exchange rate in Colombia to a terms of trade shock?

    DEFF Research Database (Denmark)

    Parra-Alvarez, Juan Carlos; Mahadeva, Lavan

    2012-01-01

    We show that the sensitivity of the real exchange rate to terms of trade shocks is greater the lower the elasticity of final and derived demand between domestic and imported items. We develop a novel Kalman filter-based method to estimate these key parameters for Colombia, taking account of prefe...... the sensitivity of the Colombian economy to external shocks....

  1. Quality control of Photosystem II: the mechanisms for avoidance and tolerance of light and heat stresses are closely linked to membrane fluidity of the thylakoids

    Directory of Open Access Journals (Sweden)

    Yasusi Yamamoto

    2016-08-01

    Full Text Available When oxygenic photosynthetic organisms are exposed to excessive light and/or heat, Photosystem II is damaged and electron transport is blocked. In these events, reactive oxygen species, endogenous radicals and lipid peroxidation products generated by photochemical reaction and/or heat cause the damage. Regarding light stress, plants first dissipate excessive light energy captured by light-harvesting chlorophyll protein complexes as heat to avoid the hazards, but once light stress is unavoidable, they tolerate the stress by concentrating damage in a particular protein in photosystem II, i.e. the reaction-center binding D1 protein of Photosystem II. The damaged D1 is removed by specific proteases and replaced with a new copy produced through de novo synthesis (reversible photoinhibition. When light intensity becomes extremely high, irreversible aggregation of D1 occurs and thereby D1 turnover is prevented. Once the aggregated products accumulate in Photosystem II complexes, removal of them by proteases is difficult, and irreversible inhibition of Photosystem II takes place (irreversible photoinhibition. Important is that various aspects of both the reversible and irreversible photoinhibition are highly dependent on the membrane fluidity of the thylakoids. Heat stress-induced inactivation of photosystem II is an irreversible process, which may be also affected by the fluidity of the thylakoid membranes. Here I describe why the membrane fluidity is a key to regulate the avoidance and tolerance of Photosystem II on environmental stresses.

  2. Growth and membrane fluidity of food-borne pathogen Listeria monocytogenes in the presence of weak acid preservatives and hydrochloric acid

    Directory of Open Access Journals (Sweden)

    Ioannis eDiakogiannis

    2013-06-01

    Full Text Available This study addresses a major issue in microbial food safety, the elucidation of correlations between acid stress and changes in membrane fluidity of the pathogen Listeria monocytogenes. In order to assess the possible role that membrane fluidity changes play in L. monocytogenes tolerance to antimicrobial acids (acetic, lactic, hydrochloric acid at low pH or benzoic acid at neutral pH, the growth of the bacterium and the gel-to-liquid crystalline transition temperature point (Tm of cellular lipids of each adapted culture was measured and compared with unexposed cells. The Tm of extracted lipids was measured by Differential Scanning Calorimetry (DSC. A trend of increasing Tm values but not of equal extent was observed upon acid tolerance for all samples and this increase is not directly proportional to each acid antibacterial action. The smallest increase in Tm value was observed in the presence of lactic acid, which presented the highest antibacterial action. In the presence of acids with high antibacterial action such as acetic, hydrochloric acid or low antibacterial action such as benzoic acid, increased Tm values were measured. The Tm changes of lipids were also correlated with our previous data about fatty acid changes to acid adaptation. The results imply that the fatty acid changes are not the sole adaptation mechanism for decreased membrane fluidity (increased Tm. Therefore, this study indicates the importance of conducting an in-depth structural study on how acids commonly used in food systems affect the composition of individual cellular membrane lipid molecules.

  3. Growth, fatty acid profile in major lipid classes and lipid fluidity of Aurantiochytrium mangrovei SK-02 As a function of growth temperature.

    Science.gov (United States)

    Chodchoey, Kanokwan; Verduyn, Cornelis

    2012-01-01

    Aurantiochytrium mangrovei Sk-02 was grown in a medium containing glucose (40 g/l), yeast extract (10 g/L) and sea salts (15 g/L) at temperatures ranging from 12 to 35°C. The fastest growth (µmax= 0.15 h(-1)) and highest fatty acid content of 415 mg/g-dry cell weight were found in the cells grown at 30°C. However, the cells grown at 12°C showed the highest percentage of polyunsaturated fatty acid (PUFA) (48.6% of total fatty acid). The percentage of docosahexaenoic acid (DHA) and pentadecanoic acid (C15:0) decreased with an increase in the growth temperature, whereas, palmitic acid (C16:0), stearic acid (C18:0) and DPA (C22:5n6) increased with an increase in the growth temperature. The composition of the major lipid class (%w/w) was slightly affected by the growth temperature. The fluidity of the organelle membrane or intracellular lipid (by DPH measurement) decreased with an increase in the growth temperatures, while the plasma membrane fluidity (by TMA-DPH measurement) could still maintain its fluidity in a wide range of temperatures (15 - 37°C). Furthermore, the distribution of DHA was found to be higher (36 - 54%) in phospholipid (PL) as compared to neutral lipid (NL) (20 - 41%).

  4. A highly sensitive protocol for the determination of Hg(2+) in environmental water using time-gated mode.

    Science.gov (United States)

    Huang, Dawei; Niu, Chenggang; Zeng, Guangming; Wang, Xiaoyu; Lv, Xiaoxiao

    2015-01-01

    In this paper, a sensitive time-gated fluorescent sensing strategy for mercury ions (Hg(2+)) monitoring is developed based on Hg(2+)-mediated thymine (T)-Hg(2+)-T structure and the mechanism of fluorescence resonance energy transfer from Mn-doped CdS/ZnS quantum dots to graphene oxide. The authors employ two T-rich single-stranded DNA (ssDNA) as the capture probes for Hg(2+), and one of them is modified with Mn-doped CdS/ZnS quantum dots. The addition of Hg(2+) makes the two T-rich ssDNA hybrids with each other to form stable T-Hg(2+)-T coordination chemistry, which makes Mn-doped CdS/ZnS quantum dots far away from the surface of graphene oxide. As a result, the fluorescence signal is increased obviously compared with that without Hg(2+). The time-gated fluorescence intensities are linear with the concentrations of Hg(2+) in the range from 0.20 to 10 nM with a limit of detection of 0.11 nM. The detection limit is much lower than the U.S. Environmental Protection Agency limit of the concentration of Hg(2+) for drinking water. The time-gated fluorescent sensing strategy is specific for Hg(2+) even with interference by other metal ions based on the results of selectivity experiments. Importantly, the proposed sensing strategy is applied successfully to the determination of Hg(2+) in environmental water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Hollow nanogold microsphere-signalized lateral flow immuno dipstick for the sensitive determination of the neurotoxin brevetoxin B

    International Nuclear Information System (INIS)

    Zhang, Kangyao; Wu, Jiachang; Li, Yineng; Wu, Yarong; Huang, Tianfu; Tang, Dianping

    2014-01-01

    We report on a new membrane-based lateral-flow assay for the rapid determination of the algal biotoxin brevetoxin B (BrevTox) that can be found in fish. Hollow nanogold microspheres (HGMS) with an average size of 45 nm were synthesized by using the reverse micelle method, followed by functionalization with monoclonal mouse anti-BrevTox antibody (mAb-HGMS). They served as the signalling reagent. Bovine serum albumin-BrevTox conjugate and rabbit anti-mouse IgG antibody were manually spotted on the nitrocellulose membrane and served as reagents for the test line and control line, respectively. Both spherical gold nanoparticle-labeled anti-BrevTox antibody (mAb-AuNP) and mAb-HGMS conjugate were investigated with respect to their suitability as signal-transduction tags, and the latter was found to give improved analytical features. The HGMS-based labeling method was then also studied in terms of performance in the immuno dipstick assay. Under optimal conditions, the visual detection limit (cut-off value) of the mAb-AuNP based assay is 1.5 ng mL −1 , while the sensitivity of the mAb-HGMS based assay is as low as 0.1 ng mL −1 . Yes/no decisions can be made within 10 min without the need for expensive instrumentation. The results for the analysis of target BrevTox in spiked fish samples showed a good correlation with data obtained with the commercial ELISA. Importantly, the assay gave no false negative results. (author)

  6. Sensitization of uranium fluorescence using 2,6-pyridinedicarboxylic acid: Application for the determination of uranium in the presence of lanthanides

    International Nuclear Information System (INIS)

    Maji, S.; Viswanathan, K.S.

    2009-01-01

    The 2,6-pyridinedicarboxylic acid (PDA) has been shown to efficiently sensitize and enhance the fluorescence of uranium in aqueous medium. Interestingly, this ligand stabilizes the UO 2 2+ species, which without the ligand is known to be in a negligible concentration, in aqueous medium at pH 6. The ligand sensitized enhancement of UO 2 2+ fluorescence by PDA, provides an analytical tool for the determination of uranium at trace levels, in aqueous medium. Furthermore, PDA is also known to enhance the fluorescence of lanthanides; consequently, the simultaneous determination of uranium and lanthanides, using PDA as a fluorescence sensitizing agent, becomes a possibility, which has been demonstrated in this work. We have shown that the use of PDA yields detection limits of 2.2x10 -7 M for UO 2 2+ , 1x10 -8 M for Tb 3+ and 5x10 -9 M for Eu 3+ in the simultaneous determination of these analytes.

  7. A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

    International Nuclear Information System (INIS)

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-01-01

    An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y_2O_3NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y_2O_3NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE_p) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y_2O_3NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE_p for ACT at Y_2O_3NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10"−"1"0 to 1.8 × 10"−"8 M with a detection limit of 3.0 × 10"−"1"1 M (based on 3S_b/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

  8. A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

    Energy Technology Data Exchange (ETDEWEB)

    Baytak, Aysegul Kutluay [Department of Medical Laboratory, Vocational School of Health Services, Harran University, Şanlıurfa 63510 (Turkey); Teker, Tugce; Duzmen, Sehriban [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey); Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey)

    2016-09-01

    An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y{sub 2}O{sub 3}NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y{sub 2}O{sub 3}NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE{sub p}) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y{sub 2}O{sub 3}NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE{sub p} for ACT at Y{sub 2}O{sub 3}NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10{sup −10} to 1.8 × 10{sup −8} M with a detection limit of 3.0 × 10{sup −11} M (based on 3S{sub b}/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

  9. Clinical diagnostic value of determination of serum lschemia modified albumin, homocysteine and high-sensitivity C-reactive protein levels in patients with acute coronary syndrome

    International Nuclear Information System (INIS)

    Lu Weiqun; Jiang Donglin; Lu Weigu

    2009-01-01

    Objective: To study the clinical diagnostic value of determination of serum ischemia modified albumin (IMA), homocysteine (Hcy) and high-sensitivity C-reactive protein (hs-CRP) levels in patients with acute coronary syndrome (ACS). Methods: Serum IMA (with albumin-cobalt binding assay), Hcy (with ELISA) and hs-CRP (with RIA) levels were determined in 73 patients with ACS within 3 hours after onset of chest pain and 40 controls. Results: The sensitivity of IMA was 87.67%, the specificity was 100%. The area under curve of ROC was 0.985 (95% confidence interval 0.969 ∼ 1.001). All the figures were higher than those of Hcy and hs-CRP. Combined determination of IMA, Hcy and hs-CRP, would increass the sensitivity to 97.26%. Conclusion: IMA is one of the earliest sensitive indicators for clinical diagnosis of early myocardial ischemia in patients with ACS. Combined determination of IMA, Hcy and hs-CRP would be even more sensitive. (authors)

  10. F2α-isoprostane, Na+-K+ ATPase and membrane fluidity of placental syncytiotrophoblast cell in preeclamptic women with vitamin E supplementation

    Directory of Open Access Journals (Sweden)

    Franciscus D. Suyatna

    2012-11-01

    Full Text Available Background: The aim of our study was to analyze F2α-isoprostane level, Na+-K+ ATPase activity and placental syncytiotrophoblast cell membrane fluidity in preeclamptic women who received vitamin E supplementation.Methods: The study was conducted between September 2003 and February 2005 at Budi Kemuliaan Maternity Hospital, Central Jakarta. Samples were 6 preeclamptic women with vitamin E supplementation, 6 preeclamptic women without vitamin E supplementation and 6 normal pregnant women. The dose of vitamin E was 200 mg daily. F2α-isoprostane was measured with ELISA reader at λ of 450 nm. Cell membrane fluidity was measured by comparing the molar ratio of total cholesterol and cell membrane phospholipid concentration. The cholesterol was measured by Modular C800 using Roche reagent. Phospholipid was measured by Shimadzu RF5301PC spectrofluorometer (excitation 267 nm, emission 307 nm. Na+-K+ ATPase activity was inhibited by ouabain. Pi production was measured with Fiske and Subbarow method using spectrophotometer at λ of 660 nm. Data was analyzed using F test with one-way ANOVA.Results: Vitamin E supplementation in preeclamptic women decreased the oxidative stress, indicated by significantly lower level of F2α-isoprostane compared to those without vitamin E (26.72 ± 11.21 vs 41.85 ± 7.09 ng/mL, respectively, p = 0.017. Membrane fluidity in syncytiotrophoblast cell of preeclampsia with vitamin E group was maintained at 0.39 ± 0.08 while in those without vitamin E was 0.53 ± 0.14 (p = 0.04. Na+-K+ ATPase activity in syncytiotrophoblast cell membrane was not affected by vitamin E (p = 0.915.Conclusion: Vitamin E supplementation in preeclamptic women decreases F2α-isoprostane level and maintains cell membrane fluidity of syncytiotrophoblast cells; however, it does not increase Na+-K+ ATPase enzyme activity. (Med J Indones. 2012;21:225-9Keywords: F2α-isoprostane, membrane fluidity, Na+-K+ ATPase, preeclampsia, vitamin E

  11. Sensitivity to Peer Evaluation and Its Genetic and Environmental Determinants: Findings from a Population-Based Twin Study.

    Science.gov (United States)

    Klippel, Annelie; Reininghaus, Ulrich; Viechtbauer, Wolfgang; Decoster, Jeroen; Delespaul, Philippe; Derom, Cathérine; de Hert, Marc; Jacobs, Nele; Menne-Lothmann, Claudia; Rutten, Bart; Thiery, Evert; van Os, Jim; van Winkel, Ruud; Myin-Germeys, Inez; Wichers, Marieke

    2018-02-23

    Adolescents and young adults are highly focused on peer evaluation, but little is known about sources of their differential sensitivity. We examined to what extent sensitivity to peer evaluation is influenced by interacting environmental and genetic factors. A sample of 354 healthy adolescent twin pairs (n = 708) took part in a structured, laboratory task in which they were exposed to peer evaluation. The proportion of the variance in sensitivity to peer evaluation due to genetic and environmental factors was estimated, as was the association with specific a priori environmental risk factors. Differences in sensitivity to peer evaluation between adolescents were explained mainly by non-shared environmental influences. The results on shared environmental influences were not conclusive. No impact of latent genetic factors or gene-environment interactions was found. Adolescents with lower self-rated positions on the social ladder or who reported to have been bullied more severely showed significantly stronger responses to peer evaluation. Not genes, but subjective social status and past experience of being bullied seem to impact sensitivity to peer evaluation. This suggests that altered response to peer evaluation is the outcome of cumulative sensitization to social interactions.

  12. A simple and sensitive fluorescence based biosensor for the determination of uric acid using H2O2-sensitive quantum dots/dual enzymes.

    Science.gov (United States)

    Azmi, Nur Ellina; Ramli, Noor Izaanin; Abdullah, Jaafar; Abdul Hamid, Mohammad Azmi; Sidek, Hamidah; Abd Rahman, Samsulida; Ariffin, Nurhayati; Yusof, Nor Azah

    2015-05-15

    A novel optical detection system consisting of combination of uricase/HRP-CdS quantum dots (QDs) for the determination of uric acid in urine sample is described. The QDs was used as an indicator to reveal fluorescence property of the system resulting from enzymatic reaction of uricase and HRP (horseradish peroxidase), which is involved in oxidizing uric acid to allaintoin and hydrogen peroxide. The hydrogen peroxide produced was able to quench the QDs fluorescence, which was proportional to uric acid concentration. The system demonstrated sufficient activity of uricase and HRP at a ratio of 5U:5U and pH 7.0. The linearity of the system toward uric acid was in the concentration range of 125-1000 µM with detection limit of 125 µM. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Determination of characteristics of degenerative joint disease using optical coherence tomography and polarization sensitive optical coherence tomography.

    Science.gov (United States)

    Xie, Tuqiang; Guo, Shuguang; Zhang, Jun; Chen, Zhongping; Peavy, George M

    2006-10-01

    Previous studies have demonstrated that optical coherence tomography (OCT) could be used to delineate alterations in the microstructure of cartilage, and have suggested that changes in the polarization state of light as detected by OCT could provide information on the birefringence properties of articular cartilage as influenced by disease. In this study we have used both OCT and polarization sensitive optical coherence tomography (PS-OCT) technologies to evaluate normal and abnormal bovine articular cartilage according to established structural, organizational, and birefringent characteristics of degenerative joint disease (DJD) in order to determine if this technology can be used to differentiate various stages of DJD as a minimally invasive imaging tool. Fresh bovine femoral-tibial joints were obtained from an abattoir, and 45 cartilage specimens were harvested from 8 tibial plateaus. Whole ex vivo specimens of normal and degenerative articular cartilage were imaged by both OCT and PS-OCT, then fixed and processed for histological evaluation. OCT/PS-OCT images and corresponding histology sections of each specimen were scored according to a modified Mankin structural grading scale and compared. OCT and PS-OCT imaging allowed structural evaluation of intact articular cartilage along a 6 mm surface length to a depth of 2 mm with a transverse resolution of 12 microm and an axial resolution of 10 microm. The OCT and PS-OCT images demonstrated characteristic alterations in the structure of articular cartilage with a high correlation to histological evaluation (kappa = 0.776). The OCT images were able to demonstrate early to advanced structural changes of articular cartilage while the optical phase retardation images obtained by PS-OCT imaging were able to discriminate areas where disorganization of the cartilage matrix was present, however, these characteristics are much different than those reported where OCT images alone were used to characterize tissue

  14. IgE Sensitization Patterns to Commonly Consumed Foods Determined by Skin Prick Test in Korean Adults.

    Science.gov (United States)

    Kim, Sung Ryeol; Park, Hye Jung; Park, Kyung Hee; Lee, Jae-Hyun; Park, Jung-Won

    2016-08-01

    Offending food allergens can vary with regional preferences in food consumption. In this study, we analysed sensitization rates to commonly consumed foods in Korean adults suspected of having food allergy. One hundred and thirty four subjects underwent a skin prick test (SPT) with 55 food allergens, of which 13 were made by our laboratory and the rest were commercially purchased. Of the 134 patients, 73 (54.5%) were sensitized to one or more food allergens. Sensitization to chrysalis was detected most frequently, at a rate of 25.4%. Sensitization rates to other food allergens were as follows: maize grain (13.4%), shrimp (11.9%), almond (11.1%), wheat flour (8.2%), lobster (8.2%), buckwheat (8.2%), mackerel (5.2%), pollack (5.2%), halibut (4.5%), peanut (4.5%), anchovy (4.4%), squid (3.7%), saury (3.0%), common eel (3.0%), yellow corvina (3.0%), hairtail (2.2%), octopus (2.2%), and others. In addition to well-known food allergens, sensitivity to mackerel, chrysalis, pollack, and halibut, which are popular foods in Korea, was observed at high rates in Korean adults. We suggest that the SPT panel for food allergy in Korea should include these allergens.

  15. IgE Sensitization Patterns to Commonly Consumed Foods Determined by Skin Prick Test in Korean Adults

    Science.gov (United States)

    2016-01-01

    Offending food allergens can vary with regional preferences in food consumption. In this study, we analysed sensitization rates to commonly consumed foods in Korean adults suspected of having food allergy. One hundred and thirty four subjects underwent a skin prick test (SPT) with 55 food allergens, of which 13 were made by our laboratory and the rest were commercially purchased. Of the 134 patients, 73 (54.5%) were sensitized to one or more food allergens. Sensitization to chrysalis was detected most frequently, at a rate of 25.4%. Sensitization rates to other food allergens were as follows: maize grain (13.4%), shrimp (11.9%), almond (11.1%), wheat flour (8.2%), lobster (8.2%), buckwheat (8.2%), mackerel (5.2%), pollack (5.2%), halibut (4.5%), peanut (4.5%), anchovy (4.4%), squid (3.7%), saury (3.0%), common eel (3.0%), yellow corvina (3.0%), hairtail (2.2%), octopus (2.2%), and others. In addition to well-known food allergens, sensitivity to mackerel, chrysalis, pollack, and halibut, which are popular foods in Korea, was observed at high rates in Korean adults. We suggest that the SPT panel for food allergy in Korea should include these allergens. PMID:27478328

  16. USE OF SENSITIVITY ANALYSIS ON A PHYSIOLOGICALLY-BASED PHARMACOKINETIC (PBPK) MODEL FOR CHLOROFORM IN RATS TO DETERMINE AGE-RELATED TOXICITY

    Science.gov (United States)

    USE OF SENSITIVITY ANALYSIS ON A PHYSIOLOGICALLY BASED PHARMACOKINETIC (PBPK) MODEL FOR CHLOROFORM IN RATS TO DETERMINE AGE-RELATED TOXICITY.CR Eklund, MV Evans, and JE Simmons. US EPA, ORD, NHEERL, ETD,PKB, Research Triangle Park, NC. Chloroform (CHCl3) is a disinfec...

  17. Determination of the lactone and lactone plus carboxylate forms of 9-aminocamptothecin in human plasma by sensitive high-performance liquid chromatography with fluorescence detection

    NARCIS (Netherlands)

    W.J. Loos (Walter); A. Sparreboom (Alex); J. Verweij (Jaap); K. Nooter (Kees); G. Stoter (Gerrit); J.H.M. Schellens (Jan)

    1997-01-01

    textabstractTwo sensitive reversed-phase high-performance liquid chromatographic fluorescence methods, with simple sample handling at the site of the patient, are described for the determination of the lactone and lactone plus carboxylate forms of g-aminocamptothecin (9AC). For 9AC lactone, the

  18. Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid-liquid extraction

    Science.gov (United States)

    A method for the highly sensitive determination of 2-, 3- and 4- nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the i...

  19. Liquid-phase exfoliated graphene as highly-sensitive sensor for simultaneous determination of endocrine disruptors: Diethylstilbestrol and estradiol

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Lintong; Cheng, Qin [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Danchao; Ma, Ming [Ningbo Entry-exit Inspection and Quarantine Bureau of China, Ningbo 315012 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-02-11

    Graphical abstract: - Highlights: • A novel electrochemical sensor was developed for diethylstilbestrol and estradiol. • Graphene prepared by solvent exfoliation greatly enhances the detection sensitivity. • The newly-developed method has promising application and the accuracy is good. - Abstract: It is quite important to develop convenient and rapid analytical methods for trace levels of endocrine disruptors because they heavily affect health and reproduction of humans and animals. Herein, graphene was easily prepared via one-step exfoliation using N-methyl-2-pyrrolidone as solvent, and then used to construct an electrochemical sensor for highly-sensitive detection of diethylstilbestrol (DES) and estradiol (E2). On the surface of prepared graphene film, two independent and greatly-increased oxidation waves were observed at 0.28 V and 0.49 V for DES and E2. The remarkable signal enlargements indicated that the detection sensitivity was improved significantly. The influences of pH value, amount of graphene and accumulation time on the oxidation signals of DES and E2 were discussed. As a result, a highly-sensitive and rapid electrochemical method was newly developed for simultaneous detection of DES and E2. The values of detection limit were evaluated to be 10.87 nM and 4.9 nM for DES and E2. Additionally, this new method was successfully used in lake water samples and the accuracy was satisfactory.

  20. Copper transporters and chaperones CTR1, CTR2, ATOX1, and CCS as determinants of cisplatin sensitivity.

    Science.gov (United States)

    Bompiani, Kristin M; Tsai, Cheng-Yu; Achatz, Felix P; Liebig, Janika K; Howell, Stephen B

    2016-09-01

    The development of resistance to cisplatin (cDDP) is commonly accompanied by reduced drug uptake or increased efflux. Previous studies in yeast and murine embryonic fibroblasts have reported that the copper (Cu) transporters and chaperones participate in the uptake, efflux, and intracellular distribution of cDDP. However, there is conflicting data from studies in human cells. We used CRISPR-Cas9 genome editing to individually knock out the human copper transporters CTR1 and CTR2 and the copper chaperones ATOX1 and CCS. Isogenic knockout cell lines were generated in both human HEK-293T and ovarian carcinoma OVCAR8 cells. All knockout cell lines had slowed growth compared to parental cells, small changes in basal Cu levels, and varying sensitivities to Cu depending on the gene targeted. However, all of the knockouts demonstrated only modest 2 to 5-fold changes in cDDP sensitivity that did not differ from the range of sensitivities of 10 wild type clones grown from the same parental cell population. We conclude that, under basal conditions, loss of CTR1, CTR2, ATOX1, or CCS does not produce a change in cisplatin sensitivity that exceeds the variance found within the parental population, suggesting that they are not essential to the mechanism by which cDDP enters these cell lines and is transported to the nucleus.

  1. Gene expression profiles in auricle skin as a possible additional endpoint for determination of sensitizers: A multi-endpoint evaluation of the local lymph node assay.

    Science.gov (United States)

    Tsuchiyama, Hiromi; Maeda, Akihisa; Nakajima, Mayumi; Kitsukawa, Mika; Takahashi, Kei; Miyoshi, Tomoya; Mutsuga, Mayu; Asaoka, Yoshiji; Miyamoto, Yohei; Oshida, Keiyu

    2017-10-05

    suggest that multi-endpoint analysis in the LLNA leads to a better determination of the sensitizing potential of test substances. We also show that the gene expression of CXCL1 and/or CXCL2, which is involved in elicitation of contact hypersensitivity (CHS), can be a possible additional endpoint for discrimination of sensitizing compounds in LLNA. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Mitochondrial fission determines cisplatin sensitivity in tongue squamous cell carcinoma through the BRCA1–miR-593-5p–MFF axis

    Science.gov (United States)

    Chen, Weixiong; Chen, Weiliang; Tang, Qionglan; Wang, Youyuan; Su, Yuxiong; Jin, Shaowen; Zhang, Daming; Zhong, Jianglong; Li, Yilin; Wen, Bin; Zhang, Zhang; Yang, Pu; Zhou, Bin; Liang, Qixiang; Yu, Xing; Zhu, Yinghua; Hu, Pengnan; Chu, Junjun; Huang, Wei; Feng, Yuhuan; Peng, Hongzhuang; Huang, Qihong; Song, Erwei; Li, Jinsong

    2015-01-01

    Cisplatin has been widely employed as a cornerstone chemotherapy treatment for a wide spectrum of solid neoplasms; increasing tumor responsiveness to cisplatin has been a topic of interest for the past 30 years. Strong evidence has indicated that mitochondrial fission participates in the regulation of apoptosis in many diseases; however, whether mitochondrial fission regulates cisplatin sensitivity remains poorly understood. Here, we show that MFF mediated mitochondrial fission and apoptosis in tongue squamous cell carcinoma (TSCC) cells after cisplatin treatment and that miR-593-5p was downregulated in this process. miR-593-5p attenuated mitochondrial fission and cisplatin sensitivity by targeting the 3′ untranslated region sequence of MFF and inhibiting its translation. In exploring the underlying mechanism of miR-593-5p downregulation, we observed that BRCA1 transactivated miR-593-5p expression and attenuated cisplatin sensitivity in vitro. The BRCA1-miR-593-5p-MFF axis also affected cisplatin sensitivity in vivo. Importantly, in a retrospective analysis of multiple centers, we further found that the BRCA1-miR-593-5p-MFF axis was significantly associated with cisplatin sensitivity and the survival of patients with TSCC. Together, our data reveal a model for mitochondrial fission regulation at the transcriptional and post-transcriptional levels; we also reveal a new pathway for BRCA1 in determining cisplatin sensitivity through the mitochondrial fission program. PMID:25912308

  3. A sensitive kinetic spectrophotometric determination of traces of tungsten in solution based on its inhibitory effect on the decolorization reaction of potassium permanganate

    Directory of Open Access Journals (Sweden)

    Petković Branka

    2016-01-01

    Full Text Available The present work describes a rapid and sensitive method for the determination of ultra micro amounts of tungsten (VI based on its inhibitory effect on the oxidation of 4-hidroxycoumarine by potassium permanganate in the presence of hydrochloric acid. The sensitivity of the method is 20 ng/cm3. The probable relative error is -4.8-13 % for the W(VI concentration range 250 to 20 ng/cm3, respectively. Kinetic equations for the investigated process which determine the order of the reactions regarding to each reaction parameter under certain experimental conditions were proposed, and they allowed quantification of the unknown concentrations W(VI in solution. The detection and quantification limit of the method are 4.5 and 15.1 ng/cm3. The effects of certain foreign ions upon the reaction rate were determined for the assessing the selectivity of the method.

  4. tRNA modifying enzymes, NSUN2 and METTL1, determine sensitivity to 5-fluorouracil in HeLa cells.

    Directory of Open Access Journals (Sweden)

    Mayumi Okamoto

    2014-09-01

    Full Text Available Nonessential tRNA modifications by methyltransferases are evolutionarily conserved and have been reported to stabilize mature tRNA molecules and prevent rapid tRNA decay (RTD. The tRNA modifying enzymes, NSUN2 and METTL1, are mammalian orthologs of yeast Trm4 and Trm8, which are required for protecting tRNA against RTD. A simultaneous overexpression of NSUN2 and METTL1 is widely observed among human cancers suggesting that targeting of both proteins provides a novel powerful strategy for cancer chemotherapy. Here, we show that combined knockdown of NSUN2 and METTL1 in HeLa cells drastically potentiate sensitivity of cells to 5-fluorouracil (5-FU whereas heat stress of cells revealed no effects. Since NSUN2 and METTL1 are phosphorylated by Aurora-B and Akt, respectively, and their tRNA modifying activities are suppressed by phosphorylation, overexpression of constitutively dephosphorylated forms of both methyltransferases is able to suppress 5-FU sensitivity. Thus, NSUN2 and METTL1 are implicated in 5-FU sensitivity in HeLa cells. Interfering with methylation of tRNAs might provide a promising rationale to improve 5-FU chemotherapy of cancer.

  5. The TRPM6 Kinase Domain Determines the Mg·ATP Sensitivity of TRPM7/M6 Heteromeric Ion Channels*

    Science.gov (United States)

    Zhang, Zheng; Yu, Haijie; Huang, Junhao; Faouzi, Malika; Schmitz, Carsten; Penner, Reinhold; Fleig, Andrea

    2014-01-01

    The transient receptor potential melastatin member 7 (TRPM7) and member 6 (TRPM6) are divalent cation channel kinases essential for magnesium (Mg2+) homeostasis in vertebrates. It remains unclear how TRPM6 affects divalent cation transport and whether this involves functional homomeric TRPM6 plasma membrane channels or heteromeric channel assemblies with TRPM7. We show that homomeric TRPM6 is highly sensitive to intracellular free Mg2+ and therefore unlikely to be active at physiological levels of [Mg2+]i. Co-expression of TRPM7 and TRPM6 produces heteromeric TRPM7/M6 channels with altered pharmacology and sensitivity to intracellular Mg·ATP compared with homomeric TRPM7. Strikingly, the activity of heteromeric TRPM7/M6 channels is independent of intracellular Mg·ATP concentrations, essentially uncoupling channel activity from cellular energy status. Disruption of TRPM6 kinase phosphorylation activity re-introduces Mg·ATP sensitivity to the heteromeric channel similar to that of TRPM7. Thus, TRPM6 modulates the functionality of TRPM7, and the TRPM6 kinase plays a critical role in tuning the phenotype of the TRPM7·M6 channel complex. PMID:24385424

  6. The TRPM6 kinase domain determines the Mg·ATP sensitivity of TRPM7/M6 heteromeric ion channels.

    Science.gov (United States)

    Zhang, Zheng; Yu, Haijie; Huang, Junhao; Faouzi, Malika; Schmitz, Carsten; Penner, Reinhold; Fleig, Andrea

    2014-02-21

    The transient receptor potential melastatin member 7 (TRPM7) and member 6 (TRPM6) are divalent cation channel kinases essential for magnesium (Mg(2+)) homeostasis in vertebrates. It remains unclear how TRPM6 affects divalent cation transport and whether this involves functional homomeric TRPM6 plasma membrane channels or heteromeric channel assemblies with TRPM7. We show that homomeric TRPM6 is highly sensitive to intracellular free Mg(2+) and therefore unlikely to be active at physiological levels of [Mg(2+)]i. Co-expression of TRPM7 and TRPM6 produces heteromeric TRPM7/M6 channels with altered pharmacology and sensitivity to intracellular Mg·ATP compared with homomeric TRPM7. Strikingly, the activity of heteromeric TRPM7/M6 channels is independent of intracellular Mg·ATP concentrations, essentially uncoupling channel activity from cellular energy status. Disruption of TRPM6 kinase phosphorylation activity re-introduces Mg·ATP sensitivity to the heteromeric channel similar to that of TRPM7. Thus, TRPM6 modulates the functionality of TRPM7, and the TRPM6 kinase plays a critical role in tuning the phenotype of the TRPM7·M6 channel complex.

  7. Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe3O4 Nanoparticles as an Electrochemical Sensor

    Science.gov (United States)

    Amir, Md.; Tunesi, Mawada M.; Soomro, Razium A.; Baykal, Abdülhadi; Kalwar, Nazar H.

    2018-04-01

    The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe3O4 NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe3O4 NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe3O4 NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe3O4 NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01-0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.

  8. Enhanced Sensitive Immunoassay: Noncompetitive Phage Anti-Immune Complex Assay for the Determination of Malachite Green and Leucomalachite Green

    Science.gov (United States)

    2015-01-01

    To develop a more sensitive immunoassay for malachite green (MG) and leucomalachite green (LMG), we identified the immunocomplex binding phage-borne peptides for use in the noncompetitive phage anti-immunocomplex assay (PHAIA). An anti-LMG monoclonal antibody (mAb) was used to select immunocomplex binding peptides from a circular random eight-amino-acid phage-displayed library. After three rounds of panning-elution, five peptides that bound the LMG–mAb immunocomplex were obtained. One of the phage-borne peptide clones that resulted in an assay with the highest sensitivity was chosen for further research. The concentration of LMG producing 50% of the saturated signal and the limit of detection of the assay were 7.02 and 0.55 ng/mL, respectively, with a linear range of 1.35 to 21.56 ng/mL. The PHAIA based on the same antibody was 16 times more sensitive compared to the competitive immunoassay. PHAIA was used to analyze LMG, MG, and two mixtures of spiked fish samples, with validation by high-performance liquid chromatography (HPLC) with fluorescence detector. Results showed a good correlation (R2LMG = 0.9841; R2MG = 0.993; R2Mixture = 0.9903) between the data of PHAIA and HPLC, thus the assay was an efficient method for monitoring food safety. PMID:25077381

  9. Effect of Ring Size in ω-Alicyclic Fatty Acids on the Structural and Dynamical Properties Associated with Fluidity in Lipid Bilayers.

    Science.gov (United States)

    Poger, David; Mark, Alan E

    2015-10-27

    Fatty acids containing a terminal cyclic group such as cyclohexyl and cycloheptyl are commonly found in prokaryotic membranes, especially in those of thermo-acidophilic bacteria. These so-called ω-alicyclic fatty acids have been proposed to stabilize the membranes of bacteria by reducing the fluidity in membranes and increasing lipid packing and lipid chain order. In this article, molecular dynamics simulations are used to examine the effect of 3- to 7-membered cycloalkyl saturated and unsaturated (cyclopent-2-enyl and phenyl) rings in ω-alicyclic fatty acyl chains on the structure (lipid packing, lipid chain order, and fraction of gauche defects in the chains) and dynamics (lateral lipid diffusion) of a model lipid bilayer. It was found that ω-alicyclic chains in which the ring was saturated reduced lipid condensation and lowered chain order which would be associated with enhanced fluidity. However, this effect was limited. The lateral diffusion of the lipids diminished as the ring size increased. In particular, ω-cyclohexyl and ω-cycloheptyl acyl tails led to a decrease in lipid diffusion. In contrast, ω-alicyclic acyl chains that contain an unsaturated ring promoted membrane fluidity both in terms of changes in membrane structure and lipid diffusion. This may indicate that saturated and unsaturated terminal rings in ω-alicyclic fatty acids fulfill alternative functions within membranes. Overall, the simulations suggest that ω-alicyclic fatty acids in which the terminal ring is saturated might protect the membrane of thermo-acidophilic bacteria from high-temperature and low-pH conditions through a "dynamical barrier" that would limit lipid diffusion and transmembrane diffusion of undesired ions and molecules.

  10. Lessons in Fluidity

    DEFF Research Database (Denmark)

    Dobusch, Leonhard; Schoeneborn, Dennis

    , or partial organizational arrangements, where it is difficult to uphold this distinction. Looking at the case of the hacker collective Anonymous as an extreme example of organization, this paper proposes to adopt a communication-centered perspective in order to better understand the formation...

  11. Fluidity, Identity, and Organizationality

    DEFF Research Database (Denmark)

    Dobusch, Leonhard; Schoeneborn, Dennis

    2015-01-01

    that the organizationality of a social collective is accomplished through “identity claims”—i.e., speech acts that concern what the social collective is or does—and negotiations on whether or not these claims have been made on the collective's behalf. We empirically examine the case of the hacker collective Anonymous...

  12. Relationship between the fluidity of heat-treated coals and molecular weight distributions of their solvent-soluble component; Netsushoritan no yobai kayo seibun no bunshiryo bunpu to ryudosei no kanren

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, T.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science; Kato, K. [Nippon Steel Co. Ltd., Tokyo (Japan); Fukada, K. [NKK Corp., Tokyo (Japan)

    1996-10-28

    In order to improve the coke manufacturing process, considerations were given on fluidity manifestation mechanism of heat-treated coals from molecular weight distributions of extracts of a solvent mixed with CS2-N-methyl-2-pyrrolidinone (CS2-NMP). The heat treatment was performed in an autoclave under nitrogen atmosphere at a rate of 3{degree}C/min to settings of 200 to 550{degree}C. The resultant heat-treated coal was quenched, and then extracted by using the CS2-NMP mixed solvent. The fluidity was measured by using a Gieseler plastometer. Maximum extraction rate and the highest fluidity are in linear relationship, which suggests that the extracts govern the fluidity. Since heavy caking coal has no difference in the extraction rates due to heat treatment temperature, and its molecular weight distribution trend does not change, the extracted components which have existed primarily in the original coal govern the fluidity. In semi-caking coals, polymer molecular components are extracted in a large quantity at the softening starting temperature, but the quantity decreases as the temperature rises. However, low-molecular components present no quantitative change, while polymer molecular components decompose, decrease in molecular weight, get solubilized with rising temperature, and act as a binder to cause a flow. 7 figs., 1 tab.

  13. Sensitive determination of neurotransmitters in urine by microchip electrophoresis with multiple-concentration approaches combining field-amplified and reversed-field stacking.

    Science.gov (United States)

    Zhang, Yan; Zhang, Yi; Wang, Guan; Chen, Wujuan; Li, Yi; Zhang, Yating; He, Pingang; Wang, Qingjiang

    2016-07-01

    Microchip electrophoresis (MCE) is particularly attractive as it provides high sensitivity and selectivity, short analysis time and low sample consumption. An on-line preconcentration strategy combining field-amplified stacking (FASS) and reversed-field stacking (RFS) was developed for efficient and sensitive analysis of neurotransmitters in real urine samples by MCE with laser induced fluorescence (LIF) detection. In this study, the multiple-preconcentration strategy greatly improves the sensitivity enhancement and surpass other conventional analytical methods for neurotransmitters detection. Under optimal conditions, the separation of three neurotransmitters (dopamine, norepinephrine and serotonin), was achieved within 3min with limits of detection (S/N=3) of 1.69, 2.35, and 2.73nM, respectively. The detection sensitivities were improved by 201-, 182-, and 292-fold enhancement, for the three neurotransmitters respectively. Other evaluation parameters such as linear correlation coefficients were considered as satisfactory. A real urine sample was analyzed with recoveries of 101.8-106.4%. The proposed FASS-RFS-MCE method was characterized in terms of precision, linearity, accuracy and successfully applied for rapid and sensitive determination of three neurotransmitters in human urine. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. A simple and sensitive method for the determination of fibric acids in the liver by liquid chromatography.

    Science.gov (United States)

    Karahashi, Minako; Fukuhara, Hiroto; Hoshina, Miki; Sakamoto, Takeshi; Yamazaki, Tohru; Mitsumoto, Atsushi; Kawashima, Yoichi; Kudo, Naomi

    2014-01-01

    Fibrates are used in biochemical and pharmacological studies as bioactive tools. Nevertheless, most studies have lacked information concerning the concentrations of fibric acids working inside tissues because a simple and sensitive method is not available for their quantitation. This study aimed to develop a simple and sensitive bioanalytical method for the quantitation of clofibric, bezafibric and fenofibric acids in samples of very small portions of tissues. Fibric acids were extracted into n-hexane-ethyl acetate from tissue homogenates (10 mg of liver, kidney or muscle) or serum (100 µL) and were derivatized with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC with fluorescence detection. These compounds were separated isocratically on a reversed phase with acetonitrile-water. Standard analytical curves were linear over the concentration range of 0.2-20 nmol/10 mg of liver. Precision and accuracy were within acceptable limits. Recovery from liver homogenates ranged from 93.03 to 112.29%. This method enabled the quantitation of fibric acids in 10 mg of liver from rats treated with clofibric acid, bezafibric acid or fenofibrate. From these analytical data, it became clear that there was no large difference in ratio of acyl-CoA oxidase 1 (Acox1) mRNA level to fibric acid content in the liver among the three fibric acids, suggesting that these three fibric acids have similar potency to increase expression of the Acox1 gene, which is a target of peroxisome proliferator-activated receptor α. Thus, the proposed method is a simple, sensitive and reliable tool for the quantitation of fibric acids working in vivo inside livers.

  15. Highly sensitive voltamperometric determination of pyritinol using carbon nanofiber/gold nanoparticle composite screen-printed carbon electrode

    Directory of Open Access Journals (Sweden)

    Apetrei IM

    2017-07-01

    Full Text Available Irina Mirela Apetrei,1 Constantin Apetrei2 1Department of Pharmaceutical Sciences, Medical and Pharmaceutical Research Center, Faculty of Medicine and Pharmacy, 2Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, “Dunarea de Jos” University of Galati, Galati, Romania Abstract: A novel and highly sensitive electrochemical method for the detection of pyritinol in pharmaceutical products and serum samples has been accomplished based on voltamperometric response of pyritinol in carbon nanofiber-gold nanoparticle (CNF-GNP-modified screen-printed carbon electrode (SPCE. The electrochemical response of pyritinol to CNF-GNP-modified SPCE was studied by cyclic voltammetry and square-wave voltammetry (SWV. Under optimized working conditions, the novel sensor shows excellent voltamperometric response toward pyritinol. The SWV study shows significantly enhanced electrochemical response for pyritinol in CNF-GNP-modified SPCE providing high sensitivity to the novel sensor for pyritinol detection. The peak current for pyritinol is found to be linear with the concentration in the range 1.0×10-8–5.0×10-5 M with a detection limit of 6.23×10-9 M using SWV as the detection method. The viability of the new developed sensor for the analytical purposes was studied by performing experiments on various commercial pharmaceutical products and blood serum samples, which yielded adequate recoveries of pyritinol. The novel electrochemical sensor provides high sensitivity, enhanced selectivity, good reproducibility and practical applicability. Keywords: pyritinol, carbon nanofiber, gold nanoparticle, sensor, square-wave voltammetry

  16. Development of a rapid, simple and sensitive HPLC-FLD method for determination of rhodamine B in chili-containing products.

    Science.gov (United States)

    Qi, Ping; Lin, Zhihao; Li, Jiaxu; Wang, ChengLong; Meng, WeiWei; Hong, Hong; Zhang, Xuewu

    2014-12-01

    In this work, a simple, rapid and sensitive analytical method for the determination of rhodamine B in chili-containing foodstuffs is described. The dye is extracted from samples with methanol and analysed without further cleanup procedure by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescent compounds (capsaicin and dihydrocapsaicin) on the analysis was overcome by the optimisation of mobile-phase composition. The limit of determination (LOD) and limit of quantification (LOQ) were 3.7 and 10 μg/kg, respectively. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations rhodamine B in foodstuffs. This method is suitable for the routine analysis of rhodamine B due to its sensitivity, simplicity, reasonable time and cost. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Construction of an alternative system for the determination of sensitiveness of neutron radioisotopic primary source standardization system

    International Nuclear Information System (INIS)

    Leite, Sandro Passos; Silva, Ademir Xavier da; Castro, Leonardo Curvello de; Bittencourt, Guilherme Rodrigues

    2009-01-01

    This work studied, through the Monte Carlo modelling, a irradiation system for the aqueous solution MnSO 4 to be used in the proceeding of determination of counting efficiency of the manganese sulfate bath

  18. Sensitization of uranium fluorescence using 2,6-pyridinedicarboxylic acid: Application for the determination of uranium in the presence of lanthanides

    Energy Technology Data Exchange (ETDEWEB)

    Maji, S. [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Viswanathan, K.S., E-mail: vish@igcar.gov.i [Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2009-11-15

    The 2,6-pyridinedicarboxylic acid (PDA) has been shown to efficiently sensitize and enhance the fluorescence of uranium in aqueous medium. Interestingly, this ligand stabilizes the UO{sub 2}{sup 2+} species, which without the ligand is known to be in a negligible concentration, in aqueous medium at pH 6. The ligand sensitized enhancement of UO{sub 2}{sup 2+} fluorescence by PDA, provides an analytical tool for the determination of uranium at trace levels, in aqueous medium. Furthermore, PDA is also known to enhance the fluorescence of lanthanides; consequently, the simultaneous determination of uranium and lanthanides, using PDA as a fluorescence sensitizing agent, becomes a possibility, which has been demonstrated in this work. We have shown that the use of PDA yields detection limits of 2.2x10{sup -7} M for UO{sub 2}{sup 2+}, 1x10{sup -8} M for Tb{sup 3+} and 5x10{sup -9} M for Eu{sup 3+} in the simultaneous determination of these analytes.

  19. Sensitivities of a Standard Test Method for the Determination of the pHe of Bioethanol and Suggestions for Improvement

    Directory of Open Access Journals (Sweden)

    Paul J. Brewer

    2010-11-01

    Full Text Available An assessment of the sensitivities of the critical parameters in the ASTM D6423 documentary standard method for the measurement of pHe in (bioethanol has been undertaken. Repeatability of measurements made using the same glass electrode and reproducibility between different glass electrodes have been identified as the main contributors to the uncertainty of the values produced. Strategies to reduce the uncertainty of the measurement have been identified and tested. Both increasing the time after which the pHe measurement is made following immersion in the sample, and rinsing the glass electrode with ethanol prior to immersion in the sample, have been shown to be effective in reducing the uncertainty of the numerical value produced. However, it is acknowledged that the values produced using these modified approaches may not be directly compared with those obtained using the documentary ASTM method since pHe is defined operationally by the process used to measure it.

  20. The PSA of safety-critical digital I and C system: the determination of important factors and sensitivity analysis

    International Nuclear Information System (INIS)

    Kang, H. G.; Sung, T. Y.; Eom, H. S.; Jeong, H. S.; Park, J. K.; Lee, K. Y.; Park, J. K.

    2002-01-01

    This report is prepared to suggest a practical Probabilistic Safety Assessment (PSA) methodology of safety-critical digital instrumentation and control (I and C) systems. Even though conventional probabilistic safety assessment methods are immature for applying to microprocessor-based digital systems, practical needs force to apply it because the result of probabilistic safety assessment plays very important role in proving the safety of a designed system. Microprocessors and software technologies make the digital system very complex and hard to analyze the safety of their applications. The aim of this is: (1) To summarize the factors which should be represented by the model for probabilistic safety assessment and to propose a standpoint of evaluation for digital systems. (2) To quantitatively presents the results of a mathematical case study which examines the analysis framework of the safety of digital systems in the context of the PSA. (3) To show the results of a sensitivity study for some critical factors

  1. Fabrication of gallium hexacyanoferrate modified carbon ionic liquid paste electrode for sensitive determination of hydrogen peroxide and glucose

    International Nuclear Information System (INIS)

    Haghighi, Behzad; Khosravi, Mehdi; Barati, Ali

    2014-01-01

    Gallium hexacyanoferrate (GaHCFe) and graphite powder were homogeneously dispersed into n-dodecylpyridinium hexafluorophosphate and paraffin to fabricate GaHCFe modified carbon ionic liquid paste electrode (CILPE). Mixture experimental design was employed to optimize the fabrication of GaHCFe modified CILPE (GaHCFe-CILPE). A pair of well-defined redox peaks due to the redox reaction of GaHCFe through one-electron process was observed for the fabricated electrode. The fabricated GaHCFe-CILPE exhibited good electrocatalytic activity towards reduction and oxidation of H 2 O 2 . The observed sensitivities for the electrocatalytic oxidation and reduction of H 2 O 2 at the operating potentials of + 0.8 and − 0.2 V were about 13.8 and 18.3 mA M −1 , respectively. The detection limit (S/N = 3) for H 2 O 2 was about 1 μM. Additionally, glucose oxidase (GOx) was immobilized on GaHCFe-CILPE using two methodology, entrapment into Nafion matrix and cross-linking with glutaraldehyde and bovine serum albumin, in order to fabricate glucose biosensor. Linear dynamic rage, sensitivity and detection limit for glucose obtained by the biosensor fabricated using cross-linking methodology were 0.1–6 mM, 0.87 mA M −1 and 30 μM, respectively and better than those obtained (0.2–6 mM, 0.12 mA M −1 and 50 μM) for the biosensor fabricated using entrapment methodology. - Highlights: • Gallium hexacyanoferrate modified carbon ionic liquid paste electrode was fabricated. • Mixture experimental design was used to optimize electrode fabrication. • Response trace plot was used to show the effect of electrode materials on response. • The sensor exhibited electrocatalytic activity towards H 2 O 2 reduction and oxidation. • Glucose biosensor was fabricated by immobilization of glucose oxidase on sensor

  2. Determination of the metal distribution in tooth fillings in real teeth based on element sensitive X-ray tomography

    International Nuclear Information System (INIS)

    Masschaele, B.; Mondelaers, W.; Cauwels, P.; Jolie, J.; Baechler, S.; Materna, T.

    2000-01-01

    Since a couple of centuries people are using metal tooth-fillings in order to protect their teeth. In the beginning of the 19th century the amalgam or silver fillings were introduced for to first time. Nowadays, dentists mostly use amalgam. These fillings are a mixture of silver, tin and mercury. The mercury which is abundant, about 50%, is dangerous for any living organism. Mercury has a particular affinity for the brain tissue but is also accumulated in the liver, kidneys, lungs, gastrointestinal track and jawbone. Mercury Basely crosses the placenta and is gathered in the heart, pituitary gland and liver of the fetus. It is been proven that the mercury vaporises and enter enters the body via the lungs. Since a couple of years we apply the element sensitive X-ray tomography technique on heavy elements like uranium or lead. By scanning teeth using photons having two different energies, one just below and one just above the K-edge of the element under investigation, the tomography becomes element sensitive. The experiment has been done at the ESRF, beam line ID15A, with a very intense tunable monochromatic high energy X-ray beam. We made tomographies of different teeth with 20 μm image resolution. The slices were 20 μm apart. The results after reconstruction are three dimensional mercury maps which can tell us something about the possibility of mercury diffusion into the roots of the tooth. From there the mercury could enter the blood stream and end up in the organs. (author)

  3. Enantiomeric determination of amino compounds with high sensitivity using the chiral reagents (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate.

    Science.gov (United States)

    Thorsén, G; Engström, A; Josefsson, B

    1997-10-31

    New chiral precolumn reagents, (+)- and (-)-1-(9-anthryl)-2-propyl chloroformate (APOC), are introduced for the chiral separation of amino acids and small peptides in capillary electrophoresis. Chiral separation of 17 amino acids and four small peptides as their diastereomeric 1-(9-anthryl)-2-propyl carbamate derivatives have been achieved by micellar electrokinetic chromatography. The detection limit for the derivatives is in the femtomole range with UV detection and in the attomole range with laser-induced fluorescence (LIF) detection. LIF detection was used to determine the enantiomeric excess of four APOC-derivatised peptides. The use of the new, anthracene-based reagents in conjunction with argon ion LIF makes enantiomeric determinations at ppm levels feasible. In this paper determinations below promille levels are performed without overloading the separation system.

  4. Facile and Sensitive Spectrophotometric Technique for the Determination of Carbofuran in its Formulations, Water and Grain Samples with Substituted Anilines

    Directory of Open Access Journals (Sweden)

    V. Harikishna

    2005-01-01

    Full Text Available Methods are described for the determination of carbofuran in its formulations, in water and grain samples by the diazotization coupling spectrophotometric technique, using substituted anilines such as 4-bromoaniline, 4-methylaniline and 4-aminobenzaldehyde as the coupling agents. The orange red colour formed with 4-bromoaniline shows maximum absorption at 478 nm, yellow colour obtained with 4-methylaniline have maximum absorption at 465 nm whereas a red colour derivative formed with 4-aminobenzaldehyde shows λmax at 472 nm. The methods could be successfully applied for the determination of carbofuran in its formulations, water and grain samples.

  5. Mono(pyridine-N-oxide) analog of DOTA as a suitable organic reagent for a sensitive and selective fluorimetric determination of Ln(III) ions

    Energy Technology Data Exchange (ETDEWEB)

    Vanek, Jakub [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lubal, Premysl, E-mail: lubal@chemi.muni.cz [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Sevcikova, Romana [Department of Chemistry, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno (Czech Republic); Polasek, Miloslav; Hermann, Petr [Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40, Prague (Czech Republic)

    2012-08-15

    The mono(pyridine-N-oxide) analog of the H{sub 4}dota macrocylic ligand, H{sub 3}do3a-py{sup NO}, is capable of forming thermodynamically stable and kinetically inert Ln(III) complexes. Its Eu(III) and Tb(III) complexes display a strong long-lived fluorescence as a result of the antenna effect of the pyridine-N-oxide fluorophore in the reagent. It is shown that H{sub 3}do3a-py{sup NO} can be used as a fluorogenic reagent for the determination of Eu(III) and Tb(III) at pH 6.5 and c{sub L}=1 mM. At an excitation wavelength of 286 nm, the emission maxima are 615 nm (Eu(III)-complex), and 547 nm (Tb(III)complex). Detection limits are at concentrations around 1.0 {mu}M and linearity of the method spans over 2 orders of magnitude. The method was applied to artificial and real samples (spiked mineral waters, extracts from cathode ray tube luminophore dust) and gave satisfactory results. The method is simple, rapid, and hardly interfered by other metal ions. - Graphical Abstract: A DOTA-like ligand with pyridine-N-oxide pendant arm is used for a quick, selective and sensitive determination of Eu{sup 3+} and Tb{sup 3+} ions through sensitized emission with excitation at 286 nm. The presented fluorimetric method is not interfered by transition metal or other lanthanide(III) ions and has a high dynamic range. Highlights: Black-Right-Pointing-Pointer Quick, selective and sensitive determination of Eu{sup 3+}/Tb{sup 3+} ions was developed. Black-Right-Pointing-Pointer Sensitized emission with excitation at 286 nm through pyridine-N-oxide pendant arm. Black-Right-Pointing-Pointer No interference of transition metal or other Ln(III) ions within high dynamic range.

  6. Selective and sensitive fluorimetric determination of carbendazim in apple and orange after preconcentration with magnetite-molecularly imprinted polymer

    Science.gov (United States)

    İlktaç, Raif; Aksuner, Nur; Henden, Emur

    2017-03-01

    In this study, magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent before the fluorimetric determination of carbendazim. Adsorption capacity of the magnetite-molecularly imprinted polymer was found to be 2.31 ± 0.63 mg g- 1 (n = 3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 2.3 and 7.8 μg L- 1, respectively. Calibration graph was linear in the range of 10-1000 μg L- 1. Rapidity is an important advantage of the method where re-binding and recovery processes of carbendazim can be completed within an hour. The same imprinted polymer can be used for the determination of carbendazim without any capacity loss repeatedly for at least ten times. Proposed method has been successfully applied to determine carbendazim residues in apple and orange, where the recoveries of the spiked samples were found to be in the range of 95.7-103%. Characterization of the adsorbent and the effects of some potential interferences were also evaluated. With the reasonably high capacity and reusability of the adsorbent, dynamic calibration range, rapidity, simplicity, cost-effectiveness and with suitable LOD and LOQ, the proposed method is an ideal method for the determination of carbendazim.

  7. A sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for chlorpyrifos residue determination in Chinese agricultural smaples

    Science.gov (United States)

    A monoclonal antibody-based competitive antibody-coated enzyme-linked immunosorbent assay (ELISA) was developed and optimized for determining chlorpyrifos residue in agricultural products. The IC50 and IC10 of this ELISA were 3.3 ng/mL and 0.1 ng/mL respectively. The average recoveries recovery rate...

  8. A sensitive and reproducible method for the determination of subnanogram quantities of immunoglobulin E (IgE)

    DEFF Research Database (Denmark)

    Poulsen, L K; Malling, H J; Søndergaard, I

    1986-01-01

    of a comparison between the Maxisorp assay and paper radioimmunosorbent test (PRIST) and a correlation coefficient of 0.98 (P less than 0.001) was obtained. We conclude that the Maxisorp assay is a fast and reliable assay for IgE determination in cord blood, cell culture supernatants and other highly diluted Ig...

  9. Determination of hexamethylmelamine and metabolites in plasma or serum by gas—liquid chromatography with a nitrogen-sensitive detector

    NARCIS (Netherlands)

    Hulshoff, A.; Neijt, J.P.; Smulders, C.F.A.; Loenen, A.C. van; Pinedo, H.M.

    1980-01-01

    A gas chromatographic method for the quantitative determination of hexamethylmelamine (HMM) and five of its metabolites in plasma (or serum) is described. After adjustment of the pH of the plasma sample to about 9.5, the compounds are extracted with chloroform containing 5% of isopropanol. Amyl

  10. Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices.

    Science.gov (United States)

    Mana Kialengila, Didi; Wolfs, Kris; Bugalama, John; Van Schepdael, Ann; Adams, Erwin

    2013-11-08

    Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1 μg/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample). Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Trace element determination using static high-sensitivity inductively coupled plasma optical emission spectrometry (SHIP-OES).

    Science.gov (United States)

    Engelhard, Carsten; Scheffer, Andy; Nowak, Sascha; Vielhaber, Torsten; Buscher, Wolfgang

    2007-02-05

    A low-flow air-cooled inductively coupled plasma (ICP) design for optical emission spectrometry (OES) with axial plasma viewing is described and an evaluation of its analytical capabilities in trace element determinations is presented. Main advantage is a total argon consumption of 0.6 L min(-1) in contrast to 15 L min(-1) using conventional ICP sources. The torch was evaluated in trace element determinations and studied in direct comparison with a conventional torch under the same conditions with the same OES system, ultrasonic nebulization (USN) and single-element optimization. A variety of parameters (x-y-position of the torch, rf power, external air cooling, gas flow rates and USN operation parameters) was optimized to achieve limits of detection (LOD) which are competitive to those of a conventional plasma source. Ionic to atomic line intensity ratios for magnesium were studied at different radio frequency (rf) power conditions and different sample carrier gas flows to characterize the robustness of the excitation source. A linear dynamic range of three to five orders of magnitude was determined under compromise conditions in multi-element mode. The accuracy of the system was investigated by the determination of Co, Cr, Mn, Zn in two certified reference materials (CRM): CRM 075c (Copper with added impurities), and CRM 281 (Trace elements in rye grass). With standard addition values of 2.44+/-0.04 and 3.19+/-0.21 microg g(-1) for Co and Mn in the CRM 075c and 2.32+/-0.09, 81.8+/-0.4, 32.2+/-3.9 for Cr, Mn and Zn, respectively, were determined in the samples and found to be in good agreement with the reported values; recovery rates in the 98-108% range were obtained. No influence on the analysis by the matrix load in the sample was observed.

  12. Combined determination of highly sensitive troponin T and copeptin for early exclusion of acute myocardial infarction: first experience in an emergency department of a general hospital

    Directory of Open Access Journals (Sweden)

    Lotze U

    2011-08-01

    Full Text Available Ulrich Lotze1, Holger Lemm2, Anke Heyer2, Karin Müller31Department of Internal Medicine, German Red Cross Hospital Sondershausen, Sondershausen, 2Department of Internal Medicine, 3Department of Laboratory Medicine, Saale-Unstrut Hospital Naumburg, Naumburg, GermanyBackground: The purpose of this observational study was to test the diagnostic performance of the Elecsys® troponin T high-sensitive system combined with copeptin measurement for early exclusion of acute myocardial infarction (MI in clinical practice.Methods: Troponin T high-sensitive (diagnostic cutoff: <14 pg/mL and copeptin (diagnostic cutoff: <14 pmol/L levels were determined at admission in addition to other routine laboratory parameters in patients with suspected acute MI presenting to the emergency department of a general hospital over a period of five months.Results: Data from 142 consecutive patients (mean age 71.2 ± 13.5 years, 76 men were analyzed. Final diagnoses were acute MI in 13 patients (nine ST elevation MI, four non-ST elevation MI, 9.2% unstable angina pectoris in three (2.1%, cardiac symptoms not primarily associated with myocardial ischemia in 79 (55.6%, and noncardiac disease in 47 patients (33.1%. The patients with acute MI were younger and had higher troponin T high-sensitive and copeptin values than patients without acute MI. Seventeen patients had very high copeptin values (>150 pmol/L, one of whom had a level of >700 pmol/L and died of pulmonary embolism. A troponin T high-sensitive level of <14 pg/mL in combination with copeptin <14 pmol/L at initial presentation ruled out acute MI in 45 of the 142 patients (31.7%, each with a sensitivity and negative predictive value of 100%.Conclusion: According to this early experience, a single determination of troponin T high-sensitive and copeptin may enable early and accurate exclusion of acute MI in one third of patients, even in an emergency department of a general hospital.Keywords: highly sensitive troponin T

  13. Fabrication of gallium hexacyanoferrate modified carbon ionic liquid paste electrode for sensitive determination of hydrogen peroxide and glucose

    Energy Technology Data Exchange (ETDEWEB)

    Haghighi, Behzad, E-mail: haghighi@iasbs.ac.ir; Khosravi, Mehdi; Barati, Ali

    2014-07-01

    Gallium hexacyanoferrate (GaHCFe) and graphite powder were homogeneously dispersed into n-dodecylpyridinium hexafluorophosphate and paraffin to fabricate GaHCFe modified carbon ionic liquid paste electrode (CILPE). Mixture experimental design was employed to optimize the fabrication of GaHCFe modified CILPE (GaHCFe-CILPE). A pair of well-defined redox peaks due to the redox reaction of GaHCFe through one-electron process was observed for the fabricated electrode. The fabricated GaHCFe-CILPE exhibited good electrocatalytic activity towards reduction and oxidation of H{sub 2}O{sub 2}. The observed sensitivities for the electrocatalytic oxidation and reduction of H{sub 2}O{sub 2} at the operating potentials of + 0.8 and − 0.2 V were about 13.8 and 18.3 mA M{sup −1}, respectively. The detection limit (S/N = 3) for H{sub 2}O{sub 2} was about 1 μM. Additionally, glucose oxidase (GOx) was immobilized on GaHCFe-CILPE using two methodology, entrapment into Nafion matrix and cross-linking with glutaraldehyde and bovine serum albumin, in order to fabricate glucose biosensor. Linear dynamic rage, sensitivity and detection limit for glucose obtained by the biosensor fabricated using cross-linking methodology were 0.1–6 mM, 0.87 mA M{sup −1} and 30 μM, respectively and better than those obtained (0.2–6 mM, 0.12 mA M{sup −1} and 50 μM) for the biosensor fabricated using entrapment methodology. - Highlights: • Gallium hexacyanoferrate modified carbon ionic liquid paste electrode was fabricated. • Mixture experimental design was used to optimize electrode fabrication. • Response trace plot was used to show the effect of electrode materials on response. • The sensor exhibited electrocatalytic activity towards H{sub 2}O{sub 2} reduction and oxidation. • Glucose biosensor was fabricated by immobilization of glucose oxidase on sensor.

  14. A specific and sensitive HPLC-MS/MS micromethod for milrinone plasma levels determination after inhalation in cardiac patients.

    Science.gov (United States)

    Gavra, Paul; Nguyen, Anne Q-N; Theoret, Yves; Litalien, Catherine; Denault, André Y; Varin, France

    2014-10-01

    Milrinone administered through inhalation is an emerging method aimed at specifically reducing pulmonary hypertension without affecting systemic pressures. Its administration has been shown to be useful both in patients undergoing cardiac surgery and for persistent pulmonary hypertension of the newborn. These populations are prone to receive many concomitant medications and/or blood sampling may require a low volume quantification method. To address these issues in view of pharmacokinetic studies, this article aims to develop and validate a specific and sensitive analytical assay using high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) detection for the quantification of milrinone plasma concentrations after inhalation in patients undergoing cardiac surgery. Plasma samples (50 μL) were extracted using ethyl acetate. Milrinone was separated on a C18 analytical column at 50°C. The mobile phase consisted of methanol and 10 mM ammonium acetate (45:55 vol/vol). The electrospray was operated in the negative ionization mode and monitored the following mass transitions: m/z 212.1 → 140.0 at 36 eV for milrinone and m/z 252.1 → 156.1 at 32 eV for olprinone. Calibration curves followed a quadratic regression in the concentration range of 0.3125-640 ng/mL. The lower limit of quantification is 0.3125 ng/mL and is based on a low plasma volume of 50 μL. Mean drug recovery and accuracy were ≥72.3% and 96.0%, respectively. Intraday and interday precision coefficient of variation (%) was ≤7.4% and ≤11.5%, respectively. The specificity allowed milrinone quantification in the multidrug administration conditions of cardiopulmonary bypass. This validated micromethod proved to be highly sensitive and specific while using a low volume of plasma. Its low volume and its lower limit of quantification indicate that this approach is suitable for further characterization of milrinone pharmacokinetics in both adults (inhalation) and neonates.

  15. Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa.

    Science.gov (United States)

    Liu, Xiaofei; Ying, Guangyao; Sun, Chaonan; Yang, Meihua; Zhang, Lei; Zhang, Shanshan; Xing, Xiaoyan; Li, Qian; Kong, Weijun

    2018-01-01

    The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B 1 , B 2 , G 1 , G 2 were extracted from samples by using methanol/water (70:30, v/v ) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity ( R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 μg/kg, respectively), precision (RSD sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B 1 (AFB 1 ) at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

  16. A multi-pumping flow-based procedure with improved sensitivity for the spectrophotometric determination of acid-dissociable cyanide in natural waters.

    Science.gov (United States)

    Frizzarin, Rejane M; Rocha, Fábio R P

    2013-01-03

    An analytical procedure with improved sensitivity was developed for cyanide determination in natural waters, exploiting the reaction with the complex of Cu(I) with 2,2'-biquinoline 4,4'-dicarboxylic acid (BCA). The flow system was based on the multi-pumping approach and long pathlength spectrophotometry with a flow cell based on a Teflon AF 2400(®) liquid core waveguide was exploited to increase sensitivity. A linear response was achieved from 5 to 200μg L(-1), with coefficient of variation of 1.5% (n=10). The detection limit and the sampling rate were 2μg L(-1) (99.7% confidence level), and 22h(-1), respectively. Per determination, 48ng of Cu(II), 5μg of ascorbic acid and 0.9μg of BCA were consumed. As high as 100mg L(-1) thiocyanate, nitrite or sulfite did not affect cyanide determination. Sulfide did not interfere at concentrations lower than 40 and 200μg L(-1) before or after sample pretreatment with hydrogen peroxide. The results for natural waters samples agreed with those obtained by a fluorimetric flow-based procedure at the 95% confidence level. The proposed procedure is then a reliable, fast and environmentally friendly alternative for cyanide determination in natural waters. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. The Validation of an Analytical Method for Sulfentrazone Residue Determination in Soil Using Liquid Chromatography and a Comparison of Chromatographic Sensitivity to Millet as a Bioindicator Species

    Directory of Open Access Journals (Sweden)

    Marcelo Antonio de Oliveira

    2014-07-01

    Full Text Available Commonly used herbicides, such as sulfentrazone, pose the risk of soil contamination due to their persistence, bioaccumulation and toxicity. Phytoremediation by green manure species has been tested using biomarkers, but analytical data are now required to confirm the extraction of sulfentrazone from soil. Thus, the present work was carried out to analyze sulfentrazone residues in soil based on liquid chromatography with a comparison of these values to the sensitivity of the bioindicator Pennisetum glaucum. The soil samples were obtained after cultivation of Crotalaria juncea and Canavalia ensiformis at four seeding densities and with three doses of sulfentrazone. The seedlings were collected into pots, at two different depths, after 75 days of phytoremediator sowing and then were used to determine the herbicide persistence in the soil. A bioassay with P. glaucum was carried out in the same pot. High-performance liquid chromatography (HPLC, using UV-diode array detection (HPLC/UV-DAD, was used to determine the herbicide residues. The HPLC determination was optimized and validated according to the parameters of precision, accuracy, linearity, limit of detection and quantification, robustness and specificity. The bioindicator P. glaucum was more sensitive to sulfentrazone than residue determination by HPLC. Changes in sulfentrazone concentration caused by green manure phytoremediation were accurately identified by the bioindicator. However, a true correlation between the size of the species and the analyte content was not identified.

  18. Liquid Chromatography with Tandem Mass Spectrometry: A Sensitive Method for the Determination of Dehydrodiisoeugenol in Rat Cerebral Nuclei

    Directory of Open Access Journals (Sweden)

    You-Bo Zhang

    2016-03-01

    Full Text Available A new liquid chromatography–tandem mass spectrometry (LC-MS/MS method is developed for the quantification of dehydrodiisoeugenol (DDIE in rat cerebral nuclei after single intravenous administration. DDIE and daidzein (internal standard were separated on a Diamonsil™ ODS C18 column with methanol–water containing 0.1% formic acid (81:19, v/v as a mobile phase. Detection of DDIE was performed on a positive electrospray ionization source using a triple quadrupole mass spectrometer. DDIE and daidzein were monitored at m/z 327.2→188.0 and m/z 255.0→199.2, respectively, in multiple reaction monitoring mode. This method enabled quantification of DDIE in various brain areas, including, cortex, hippocampus, striatum, hypothalamus, cerebellum and brainstem, with high specificity, precision, accuracy, and recovery. The data herein demonstrate that our new LC-MS/MS method is highly sensitive and suitable for monitoring cerebral nuclei distribution of DDIE.

  19. Rapid and sensitive spectrofluorimetric determination of enrofloxacin, levofloxacin and ofloxacin with 2,3,5,6-tetrachloro- p-benzoquinone

    Science.gov (United States)

    Ulu, Sevgi Tatar

    2009-06-01

    A highly sensitive spectrofluorimetric method was developed for the first time, for the analysis of three fluoroquinolones (FQ) antibacterials, namely enrofloxacin (ENR), levofloxacin (LEV) and ofloxacin (OFL) in pharmaceutical preparations through charge transfer (CT) complex formation with 2,3,5,6-tetrachloro- p-benzoquinone (chloranil,CLA). At the optimum reaction conditions, the FQ-CLA complexes showed excitation maxima ranging from 359 to 363 nm and emission maxima ranging from 442 to 488 nm. Rectilinear calibration graphs were obtained in the concentration range of 50-1000, 50-1000 and 25-500 ng mL -1 for ENR, LEV and OFL, respectively. The detection limit was found to be 17 ng mL -1 for ENR, 17 ng mL -1 for LEV, 8 ng mL -1 for OFL, respectively. Excipients used as additive in commercial formulations did not interfere in the analysis. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness. The proposed method was successfully applied to the analysis of pharmaceutical preparations. The results obtained were in good agreement with those obtained using the official method; no significant difference in the accuracy and precision as revealed by the accepted values of t- and F-tests, respectively.

  20. A sensitive electrochemical aptasensor based on water soluble CdSe quantum dots (QDs) for thrombin determination

    Energy Technology Data Exchange (ETDEWEB)

    Li Yanfen; Han Min [Jiangsu Laboratory of New Power Batteries, Jiangsu Key Laboratory of Biofuctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Bai Hongyan [Jiangsu Laboratory of New Power Batteries, Jiangsu Key Laboratory of Biofuctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); College of Biological and Chemical Engineering, Jiaxing College, Jiaxing 314001 (China); Wu Yong [Jiangsu Laboratory of New Power Batteries, Jiangsu Key Laboratory of Biofuctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Dai Zhihui, E-mail: daizhihuii@njnu.edu.cn [Jiangsu Laboratory of New Power Batteries, Jiangsu Key Laboratory of Biofuctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Bao Jianchun, E-mail: baojianchun@njnu.edu.cn [Jiangsu Laboratory of New Power Batteries, Jiangsu Key Laboratory of Biofuctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China)

    2011-08-01

    A novel aptamer biosensor with easy operation and good sensitivity, specificity, stability and reproducibility was developed by immobilizing the aptamer on water soluble CdSe quantum dots (QDs) modified on the top of the glassy carbon electrode (GCE). Methylene blue (MB) was intercalated into the aptamer sequence and used as an electrochemical marker. CdSe QDs improved the electrochemical signal because of their larger surface area and ion centers of CdSe QDs may also had a major role on amplifying the signal. The higher ion concentration caused more combination of aptamer which caused larger signal. The thrombin was detected by differential pulse voltammetry (DPV) quantitatively. Under optimal conditions, the two linear ranges were obtained from 3 to 13 {mu}g mL{sup -1} and from 14 to 31 {mu}g mL{sup -1}, respectively. The detection limit was 0.08 {mu}g mL{sup -1} at 3{sigma}. The constructed biosensor had better responses compared with that in the absence of the CdSe QDs immobilizing. The control experiment was also carried out by using BSA, casein and IgG in the absence of thrombin. The results showed that the aptasensor had good specificity, stability and reproducibility to the thrombin. Moreover, the aptasensor could be used for detection of real sample with consistent results in comparison with those obtained by fluorescence method which could provide a promising platform for fabrication of aptamer based biosensors.

  1. Highly sensitive amperometric biosensor based on electrochemically-reduced graphene oxide-chitosan/hemoglobin nanocomposite for nitromethane determination.

    Science.gov (United States)

    Wen, Yunping; Wen, Wei; Zhang, Xiuhua; Wang, Shengfu

    2016-05-15

    Nitromethane (CH3NO2) is an important organic chemical raw material with a wide variety of applications as well as one of the most common pollutants. Therefore it is pretty important to establish a simple and sensitive detection method for CH3NO2. In our study, a novel amperometric biosensor for nitromethane (CH3NO2) based on immobilization of electrochemically-reduced graphene oxide (rGO), chitosan (CS) and hemoglobin (Hb) on a glassy carbon electrode (GCE) was constructed. Scanning electron microscopy, infrared spectroscopy and electrochemical methods were used to characterize the Hb-CS/rGO-CS composite film. The effects of scan rate and pH of phosphate buffer on the biosensor have been studied in detail and optimized. Due to the graphene and chitosan nanocomposite, the developed biosensor demonstrating direct electrochemistry with faster electron-transfer rate (6.48s(-1)) and excellent catalytic activity towards CH3NO2. Under optimal conditions, the proposed biosensor exhibited fast amperometric response (<5s) to CH3NO2 with a wide linear range of 5 μM~1.46 mM (R=0.999) and a low detection limit of 1.5 μM (S/N=3). In addition, the biosensor had high selectivity, reproducibility and stability, providing the possibility for monitoring CH3NO2 in complex real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Sensitive determination of polycyclic aromatic hydrocarbons in water samples by HPLC coupled with SPE based on graphene functionalized with triethoxysilane.

    Science.gov (United States)

    Huang, Ke-Jing; Li, Jing; Liu, Yan-Ming; Wang, Lan

    2013-02-01

    The graphene functionalized with (3-aminopropyl) triethoxysilane was synthesized by a simple hydrothermal reaction and applied as SPE sorbents to extract trace polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. These sorbents possess high adsorption capacity and extraction efficiency due to strong adsorption ability of carbon materials and large specific surface area of nanoparticles, and only 10 mg of sorbents are required to extract PAHs from 100 mL water samples. Several condition parameters, such as eluent and its volume, adsorbent amount, sample volume, sample pH, and sample flow rate, were optimized to achieve good sensitivity and precision. Under the optimized extraction conditions, the method showed good linearity in the range of 1-100 μg/L, repeatability of the extraction (the RSDs were between 1.8 and 2.9%, n = 6), and satisfactory detection limits of 0.029-0.1 μg/L. The recoveries of PAHs spiked in environmental water samples ranged from 84.6 to 109.5%. All these results demonstrated that this new SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Diffusivities of Redox-Sensitive Elements in Basalt vs. Oxygen Fugacity Determined by LA-ICP-MS

    Science.gov (United States)

    Szumila, Ian; Danielson, Lisa; Trail, Dustin

    2017-01-01

    Several diffusion experiments were conducted in a piston cylinder device across a range of oxygen fugacities (FMQ-3 FMQ-1.2, FMQ+6) at 1 GPa and 1300 C. This was done to explore the effects of oxygen fugacity (fO2) on diffusivity of redox sensitive trace elements. This allows investigation of how these elements diffuse across the fO2 range encountered in different reservoirs on planets and moons in our solar system. The University of Rochester LA-ICP-MS system was used for analysis of samples. Analyses were conducted using an Agilent 7900 quadrupole mass spectrometer connected to a Photon Machines 193 nm G2 laser ablation (LA) system equipped with a HelEx 2-volume sample chamber. Spots used were 35 micrometers circles spaced at 65 micrometers intervals. Laser fluence was 7.81 J/cm^2 with a rep rate of 10 Hz. The iolite software package was used to reduce data collected from laser ablation analysis of experiments with Si-29 used as the internal standard isotope. Iolite's global fit module was used to simultaneously fit elements' diffusivities in each experiment while keeping the Matano interface constant. Elements analysed include V, Nb, W, Mo, La, Ce, Pr, Sm, Eu, Gd, Ta, and W. Figures

  4. Prevalence of bacterial agents isolated from clinical cases of bovine mastitis in the dry period and the determination of their antibiotic sensitivity in Tabriz, Iran

    Directory of Open Access Journals (Sweden)

    Samad Mosaferi

    2015-09-01

    Full Text Available Objective: To determine the prevalence of mastitis-causing bacteria in the dry period and its antibiotic sensitivity. Methods: In this study, 852 dry cows were examined. A total of 30 cows with clinical mastitis symptoms were detected and their milk samples were collected. In order to purify the bacteria, brain heart infusion and blood agar media were applied and single colonies were used for Gram staining, oxidase and catalase testing, cultivating in O-F medium to determine the genus and species of bacteria. Then, antimicrobial susceptibility was tested by the agar disk diffusion method. Results: The prevalence of isolated bacteria was 2.46%, in which coagulase positive Staphylococcus, coagulase negative Staphylococcus, Streptococcus dysgalactiae, Streptococcus faecalis, Escherichia coli, Pseudomonas, Bacillus and yeast were (9/99%, (6/66%, (13/32%, (3/33%, (6/66%, (13/32%, (9/99% and (6/66%, respectively. After tests of antibiotic susceptibility, the most and the least sensitivity were reported to enrofloxacin and ampicillin respectively. Conclusions: This study indicated that Streptococcus dysgalactiae is the most commonly isolated bacteria with the greatest sensitivity to enrofloxacin and tetracycline which can be used to treat mastitis in the dry period in Tabriz.

  5. Tantalum electrodes modified with well-aligned carbon nanotube-Au nanoparticles: application to the highly sensitive electrochemical determination of cefazolin.

    Science.gov (United States)

    Fayazfar, Haniyeh; Afshar, Abdollah; Dolati, Abolghasem

    2014-07-01

    Carbon nanotube/nanoparticle hybrid materials have been proven to exhibit high electrocatalytic activity suggesting broad potential applications in the field of electroanalysis. For the first time, modification of Ta electrode with aligned multi-walled carbon nanotubes/Au nanoparticles introduced for the sensitive determination of the antibiotic drug, cefazolin (CFZ). The electrochemical response characteristics of the modified electrode toward CFZ were investigated by means of cyclic and linear sweep voltammetry. The modified electrode showed an efficient catalytic activity for the reduction of CFZ, leading to a remarkable decrease in reduction overpotential and a significant increase of peak current. Under optimum conditions, the highly sensitive modified electrode showed a wide linear range from 50 pM to 50 μM with a sufficiently low detection limit of 1 ± 0.01 pM (S/N = 3). The results indicated that the prepared electrode presents suitable characteristics in terms of sensitivity (458.2 ± 2.6 μAcm(-2)/μM), accuracy, repeatability (RSD of 1.8 %), reproducibility (RSD of 2.9 %), stability (14 days), and good catalytic activity in physiological conditions. The method was successfully applied for accurate determination of trace amounts of CFZ in pharmaceutical and clinical preparations without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis.

  6. Flow injection determination of diclofenac sodium based on its sensitizing effect on the chemiluminescent reaction of acidic potassium permanganate-formaldehyde.

    Science.gov (United States)

    Song, Jingjing; Sun, Pulv; Ji, Zhongling; Li, Jianguo

    2015-02-01

    A sensitive and simple chemiluminescent (CL) method for the determination of diclofenac sodium has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between formaldehyde and acidic potassium permanganate. A calibration curve is constructed for diclofenac sodium under optimized experimental parameters over the range 0.040-5.0 µg/mL and the limit of detection is 0.020 µg/mL (3σ). The inter-assay relative standard deviation for 0.040 µg/mL diclofenac sodium (n = 11) is 2.0%. This method is rapid, sensitive, simple, and shows good selectivity and reproducibility. The proposed method has been successfully applied to the determination of the studied diclofenac sodium in pharmaceutical preparations with satisfactory results. Furthermore, the possible mechanism for the CL reaction has been discussed in detail on the basis of UV and CL spectra. Copyright © 2014 John Wiley & Sons, Ltd.

  7. Fast and sensitive determination of Sr-90 and SR-89 activity in milk by ion-chromatography and liquid scintillation

    International Nuclear Information System (INIS)

    Figueiredo, V.; Herrmann, A.

    1992-01-01

    A method for fast and exact determination of both strontium isotopes in milk and other foodstuffs, combination high performance ion chromatographic separation with by liquid scintillation counting, which enables the desired results to be obtained with very satisfactory precision and reproducibility within 24 hours, has been developed. The lowest detectable activity lies by 3 Bq/liter for Sr-90 and 1 Bq/liter for Sr-89 which is satisfactory for assessing a situation in a time crisis. (author)

  8. Graphene oxide sheets immobilized polystyrene for column preconcentration and sensitive determination of lead by flame atomic absorption spectrometry.

    Science.gov (United States)

    Islam, Aminul; Ahmad, Hilal; Zaidi, Noushi; Kumar, Suneel

    2014-08-13

    A novel solid-phase extractant was synthesized by coupling graphene oxide (GO) on chloromethylated polystyrene through an ethylenediamine spacer unit to develop a column method for the preconcentration/separation of lead prior to its determination by flame atomic absorption spectrometry. It was characterized by Fourier transform infrared spectroscopy, far-infrared spectroscopy, thermogravimetric analysis/differential thermal analysis, scanning electron microscopy, energy-dispersive spectrometry, and transmission electron microscopy. The abundant oxygen-containing surface functional groups form a strong complex with lead, resulting in higher sorption capacity (227.92 mg g(-1)) than other nanosorbents used for sorption studies of the column method. Using the column procedure here is an alternative to the direct use of GO, which restricts irreversible aggregation of GO and its escape into the ecosystem, making it an environmentally sustainable method. The column method was optimized by varying experimental variables such as pH, flow rate for sorption/desorption, and elution condition and was observed to exhibit a high preconcentration factor (400) with a low preconcentration limit (2.5 ppb) and a high degree of tolerance for matrix ions. The accuracy of the proposed method was verified by determining the Pb content in the standard reference materials and by recovery experiments. The method showed good precision with a relative standard deviation <5%. The proposed method was successfully applied for the determination of lead in tap water, electroplating wastewater, river water, and food samples after preconcentration.

  9. Development of a highly sensitive MIP based-QCM nanosensor for selective determination of cholic acid level in body fluids

    International Nuclear Information System (INIS)

    Gültekin, Aytaç; Karanfil, Gamze; Sönmezoğlu, Savaş; Say, Rıdvan

    2014-01-01

    Determination of cholic acid is very important and necessary in body fluids due to its both pharmaceutical and clinical significance. In this study, a quartz crystal microbalance (QCM) nanosensor, which is imprinted cholic acid, has been developed for the assignation of cholic acid. The cholic acid selective memories have been generated on QCM electrode surface by using molecularly imprinted polymer (MIP) based on methacryloylamidohistidine-copper (II) (MAH-Cu(II)) pre-organized monomer. The cholic acid imprinted nanosensor was characterized by atomic force microscopy (AFM) and then analytical performance of the cholic acid imprinted QCM nanosensor was studied. The detection limit was found to be 0.0065 μM with linear range of 0.01–1000 μM. Moreover, the high value of Langmuir constant (b) (7.3 * 10 5 ) obtained by Langmuir graph showed that the cholic acid imprinted nanosensor had quite strong binding sites affinity. At the last step of this procedure, cholic acid levels in body fluids were determined by the prepared imprinted QCM nanosensor. - Graphical abstract: QCM responses of the cholic acid imprinted and non-imprinted nanosensors (C CA = 0.1 μM). - Highlights: • The purpose is to synthesize a new cholic acid imprinted QCM nanosensor by MIP. • Analytical applications of QCM nanosensor were investigated. • The cholic acid levels in body fluids were determined by prepared QCM nanosensor

  10. Rapid and sensitive determination of carbohydrates in foods using high temperature liquid chromatography with evaporative light scattering detection.

    Science.gov (United States)

    Terol, Amanda; Paredes, Eduardo; Maestre, Salvador E; Prats, Soledad; Todolí, José L

    2012-04-01

    In the present work, an evaporative light scattering detector was used as a high-temperature liquid chromatography detector for the determination of carbohydrates. The compounds studied were glucose, fructose, galactose, sucrose, maltose, and lactose. The effect of column temperature on the retention times and detectability of these compounds was investigated. Column heating temperatures ranged from 25 to 175°C. The optimum temperature in terms of peak resolution and detectability with pure water as mobile phase and a liquid flow rate of 1 mL/min was 150°C as it allowed the separation of glucose and the three disaccharides here considered in less than 3 min. These conditions were employed for lactose determination in milk samples. Limits of quantification were between 2 and 4.7 mg/L. On the other hand, a temperature gradient was developed for the simultaneous determination of glucose, fructose, and sucrose in orange juices, due to coelution of monosaccharides at temperatures higher than 70°C, being limits of quantifications between 8.5 and 12 mg/L. The proposed hyphenation was successfully applied to different types of milk and different varieties of oranges and mandarins. Recoveries for spiked samples were close to 100% for all the studied analytes. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A Sensitive Determination of Carbofuran by Spectrophotometer using 4, 4-azo-bis-3, 3′5, 5′-tetra bromoaniline in various Environmental Samples

    Directory of Open Access Journals (Sweden)

    O. Bhargavi

    2006-01-01

    Full Text Available A simple and sensitive spectrophotometric technique was developed for the determination of carbofuran in its formulations, water and grain samples. The method was based on the alkaline hydrolyzed product of carbofuran phenol interacted with diazonium salt of 4,4-azo-bis-3,3′5,5′-tetra bromo aniline. The maximum absorbance of the red coloured derivative was measured at 470 nm. The beer’s law was obeyed in the concentration range of 0.1-16.0 µg/mL. The interference of the non target species were studied on the determination of carbofuran which increases the selectivity of the method. The present method was successfully applied for the determination of carbofuran in its formulations, water and grain samples.

  12. Response to vicriviroc in treatment-experienced subjects, as determined by an enhanced-sensitivity coreceptor tropism assay: reanalysis of AIDS clinical trials group A5211.

    Science.gov (United States)

    Su, Zhaohui; Gulick, Roy M; Krambrink, Amy; Coakley, Eoin; Hughes, Michael D; Han, Dong; Flexner, Charles; Wilkin, Timothy J; Skolnik, Paul R; Greaves, Wayne L; Kuritzkes, Daniel R; Reeves, Jacqueline D

    2009-12-01

    The enhanced-sensitivity Trofile assay (Monogram Biosciences) was used to retest coreceptor use at both study screening and study entry for 118 treatment-experienced subjects in AIDS Clinical Trials Group A5211 who had CCR5-tropic (R5) virus detected by the original Trofile assay at study screening. Among 90 recipients of vicriviroc, a significantly (P< .001) greater mean reduction in HIV-1 RNA was observed in 72 subjects with R5 virus versus 15 subjects reclassified as having dual/mixed-tropic viruses at screening: -1.11 versus -0.09 log(10) copies/mL at day 14 and -1.91 versus -0.57 log(10) copies/mL at week 24, respectively. Results suggest that the enhanced-sensitivity assay is a better screening tool for determining patient eligibility for CCR5 antagonist therapy.

  13. Evaluation of spatial sensitivity of a prompt gamma neutron activation analysis facility for the in vivo determination of nitrogen in small animals

    International Nuclear Information System (INIS)

    Kasviki, K.; Ioannina University; Stamatelatos, I.E.; Kalef-Ezra, J.

    2007-01-01

    We investigated the spatial dependence of the sensitivity of nitrogen measurement with a prompt gamma neutron activation analysis (PGNAA) system for small animals and developed an analysis procedure that permits the reduction of systematic errors due to that dependence. The analysis procedure is based on neutron and photon transport calculations performed using the MCNP code in order to evaluate the sensitivity of the PGNAA facility. The system can be calibrated experimentally using a small number of phantoms of known size and composition. The calculation approach can then be used to predict responses for animal body sizes and shapes relatively to those experimentally determined and to include the effect of tissue inhomogeneities. Our calculations were verified by experimental measurements performed for a set of cylindrical inhomogeneous phantoms. The calculated to experimental ratios observed were within 6%. (author)

  14. High sensitive C-reactive protein-Effective tool in determining postoperative recovery in lumbar disc disease

    Directory of Open Access Journals (Sweden)

    Tushar Narayan Rathod

    2014-01-01

    Full Text Available Background: It is common in medical practice to see patients having persistent pain and radiculopathy even after undergoing discectomy surgery. Inflammatory cytokines, such as interleukins are produced at the site of disc herniation and are now considered responsible for the pain perceived by the patient. This study has used high sensitive C-reactive protein (HSCRP assay for predicting inflammation around the nerve roots on very same principle, which has used HSCRP for predicting coronary artery diseases in current clinical practice. Thus, purpose of this study is to test whether HSCRP can stand as an objective tool to predict postoperative recovery in patients undergoing lumbar discectomy. That is, to study association between preoperative HSCRP blood level and postoperative recovery with the help of modified Oswestry Back Disability Score. Materials and Methods: A study group consisting of 50 cases of established lumbar disc disease and control group of 50 normal subjects, matched with the study group. Both the study and control groups were subjected to detailed evaluation with the help of modified Oswestry Low Back Pain Scale both pre and postoperatively at 3 months, 6 months and 1-year. The preoperative blood samples were analyzed to assess the HSCRP concentration. All the cases underwent surgery over a period of 1-year by the same surgeon. Results: The level of HSCRP in the study group was between 0.050- and 0.710 mg/dL and in the control group, 0.005-0.020 mg/dL. There was highly significant positive correlation between preoperative HSCRP level and postoperative score at P 10 points, while those with HSCRP level in the range of 0.470 ± 0.163 mg/dL, showed poor recovery (score improved < 10 points. Conclusion: HSCRP will serve as a good supplementary prognostic marker for operative decision making in borderline and troublesome cases of lumbar disc disease.

  15. Technetium-99 and strontium-90: Abundance determination at ultratrace sensitivity by AMS as signatures of undeclared nuclear reprocessing activity

    International Nuclear Information System (INIS)

    McAninch, J.E.; Proctor, I.D.

    1995-03-01

    The purpose of this White Paper is to examine the use of the ultratrace technique Accelerator Mass Spectrometry (AMS) to lower detection limits for 99 Tc and 90 Sr, and to examine the utility of these isotopes as signatures of a convert reprocessing facility. The International Atomic Energy Agency (IAEA) has committed to improving the effectiveness of the IAEA Safeguards System. This is in some degree a result of the discovery in 1991 of an undeclared Iraqi EMIS program. Recommendations from the March 1993 Consultants Group Meeting have resulted in several studies and follow on field trials to identify environmental signatures from covert nuclear fuel reprocessing activity. In particular, the April, 1993 reports of the Standing Advisory Group on Safeguards Implementation (SAGSI) identified the long-lived radioisotopes Technetium-99 and strontium-90 as two reliable signatures of fuel reprocessing activity. This report also suggested pathways in the chemical processing of irradiated fuel where these elements would be volatilized and potentially released in amounts detectable with ultratrace sensitivity techniques. Based on measured 99 Tc background levels compiled from a variety of sources, it is estimated that AMS can provide 10% measurements of environmental levels of 99 Tc in a few minutes using modestly sized samples: a few grams for soils, plants, or animal tissues; one to several liters for rain or seawater samples; and tens to hundreds of cubic meters for air sampling. Small sample sizes and high sample throughput result in significant increases in feasibility, cost effectiveness, and quality of data for a regional monitoring program. Similar results are expected for 90 Sr

  16. An accelerated stress testing program for determining the reliability sensitivity of silicon solar cells to encapsulation and metallization systems

    Science.gov (United States)

    Lathrop, J. W.; Davis, C. W.; Royal, E.

    1982-01-01

    The use of accelerated testing methods in a program to determine the reliability attributes of terrestrial silicon solar cells is discussed. Different failure modes are to be expected when cells with and without encapsulation are subjected to accelerated testing and separate test schedules for each are described. Unencapsulated test cells having slight variations in metallization are used to illustrate how accelerated testing can highlight different diffusion related failure mechanisms. The usefulness of accelerated testing when applied to encapsulated cells is illustrated by results showing that moisture related degradation may be many times worse with some forms of encapsulation than with no encapsulation at all.

  17. Highly fluorescent carbon dots as nanoprobes for sensitive and selective determination of 4-nitrophenol in surface waters

    International Nuclear Information System (INIS)

    Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García; García, Marta Elena Díaz

    2015-01-01

    We report on the synthesis of carbon dots (C-dots) by thermal carbonization of a mixture of ethyleneglycol bis-(2-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA) and tris(hydroxymethyl)aminomethane (Tris). The resulting C-dots were characterized by X-ray diffraction, proton and carbon nuclear magnetic resonance, FTIR and fluorescence spectroscopy, and high-resolution TEM. The data reveal that the C-dots are mainly capped with hydroxy and carbonyl groups and are highly fluorescent with an emission peak that shifts from 427 to 438 nm if the excitation wavelength is increased from 310 to 360–370 nm. Fluorescence is quenched by 4-nitrophenol (4-NP), and this effect was exploited to design a simple and rapid protocol for the determination of 4-NP. The detection limit is 28 nM and the linear range extends from 0.1 to 50 μM. The method was successfully applied to the determination of 4-NP in spiked river and sea waters. (author)

  18. Highly sensitive sorption-luminescence determination of trace europium with preconcentration on silica chemically modified with iminodiacetic acid

    International Nuclear Information System (INIS)

    Voronina, R.D.; Zorov, N.B.

    2007-01-01

    Features of a sorption-luminescence method for the determination of trace europium were studied. The method includes the preliminary sorption of europium at pH 7.1 from solutions with silica chemically modified with iminodiacetic acid, the subsequent treatment of the sorbent with 2-thenoyltrifluoroacetone at pH 8.0, and the measurement of the intensity of luminescence of the surface three-component europium complex at 613 nm. The effect of moisture as the quencher of luminescence of the surface europium complex was studied, and techniques for its removal were proposed. Sorption in the static mode provides the detection limit of europium of 7 x 10 -5 g/ml. The calibration plot is linear in the range of two orders of magnitude of europium concentration in solutions. The relative standard deviation in the determination of 1.5 x 10 -2 μg/ml europium is 5%. In the dynamic mode of sorption from 1000 ml of an analyzed solution with the use of sorption-desorption, the detection limit of europium of 8 x 10 -7 μg/ml was attained [ru

  19. Highly selective ionic liquid-based microextraction method for sensitive trace cobalt determination in environmental and biological samples

    International Nuclear Information System (INIS)

    Berton, Paula; Wuilloud, Rodolfo G.

    2010-01-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on an ionic liquid (IL-DLLME) was developed for selective determination of cobalt (Co) with electrothermal atomic absorption spectrometry (ETAAS) detection. Cobalt was initially complexed with 1-nitroso-2-naphtol (1N2N) reagent at pH 4.0. The IL-DLLME procedure was then performed by using a few microliters of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium hexafluorophosphate [C 6 mim][PF 6 ] as extractant while methanol was the dispersant solvent. After microextraction procedure, the Co-enriched RTIL phase was solubilized in methanol and directly injected into the graphite furnace. The effect of several variables on Co-1N2N complex formation, extraction with the dispersed RTIL phase, and analyte detection with ETAAS, was carefully studied in this work. An enrichment factor of 120 was obtained with only 6 mL of sample solution and under optimal experimental conditions. The resultant limit of detection (LOD) was 3.8 ng L -1 , while the relative standard deviation (RSD) was 3.4% (at 1 μg L -1 Co level and n = 10), calculated from the peak height of absorbance signals. The accuracy of the proposed methodology was tested by analysis of a certified reference material. The method was successfully applied for the determination of Co in environmental and biological samples.

  20. Highly sensitive and simultaneous electrochemical determination of 2-aminophenol and 4-aminophenol based on poly(l-arginine)-β-cyclodextrin/carbon nanotubes@graphene nanoribbons modified electrode.

    Science.gov (United States)

    Yi, Yinhui; Zhu, Gangbing; Wu, Xiangyang; Wang, Kun

    2016-03-15

    Owing to the similar characteristics and physiochemical property of 2-aminophenol (2-AP) and 4-aminophenol (4-AP), the highly sensitive simultaneous electrochemical determination of 2- and 4-AP is a great challenge. In this paper, by electropolymerizing β-cyclodextrin (β-CD) and l-arginine (l-Arg) on the surface of carbon nanotubes@graphene nanoribbons (CNTs@GNRs) core-shell heterostructure, a P-β-CD-l-Arg/CNTs@GNRs nanohybrid modified electrode was prepared successfully, and it could exhibit the synergetic effects of β-CD (high host-guest recognition and enrichment ability), l-Arg (excellent electrocatalytic activity) and CNTs@GNRs (prominent electrochemical properties and large surface area), the P-β-CD-l-Arg/CNTs@GNRs modified electrode was used in the electrochemical determination of 2- and 4-AP, the results demonstrated that the highly sensitive and simultaneous determination of 2- and 4-AP is successfully achieved and the modified electrode has a linear response range of 25.0-1300.0 nM for both 2- and 4-AP, and the detection limits of 2- and 4-AP obtained in this work are 6.2 and 3.5 nM, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Rapid and sensitive determination of beta-phenylethylamine in animal brains by high performance liquid chromatography with fluorometric detection.

    Science.gov (United States)

    Taga, C; Tsuji, M; Nakajima, T

    1989-05-01

    A reversed phase HPLC method with fluorometric detection for the analysis of beta-phenylethylamine has been developed using p-methoxyphenylethylamine as an internal standard. Two columns, containing 200 microL of Dowex 50-X8 and Amberlite CG-50 respectively, were used to prepare a fraction containing beta-phenylethylamine. The recoveries of beta-phenylethylamine and p-methoxyphenylethylamine were 53.9 +/- 9.4% and 68.1 +/- 12.4%, respectively, and elution profile of p-methoxyphenylethylamine was sufficiently well correlated with that of beta-phenylethylamine. Regional distributions of beta-phenylethylamine in rat and mouse brains were determined. The highest concentrations were found in hypothalamus and hippocampus in both animals.

  2. Sensitive method for the determination of sup 1 sup 8 F attached to aerosol particles in a PET centre

    CERN Document Server

    Papp, Z

    2002-01-01

    A new grab sampling method has been developed for the measurement of sup 1 sup 8 F attached to aerosol particles. It is based on direct beta-counting of filtered aerosol sample over successive time intervals by an end-window Geiger-Mueller counter. The effect of the progeny of radon and thoron on the beta-counting rate is separated by analysing the decay curve. The defined solid angle absolute counting was used to evaluate the efficiencies for sup 1 sup 8 F and for the progeny of radon and thoron one by one. Absolute activity concentration of sup 1 sup 8 F can be determined with less than 10% systematic error. Glass-fibre filter and high sampling flow rate are applied, leading to a detection limit for sup 1 sup 8 F of less than 1 Bq m sup - sup 3. The method was tested under different circumstances in the PET centre of University of Debrecen, Hungary.

  3. A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles.

    Science.gov (United States)

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-10-01

    An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO2. The ZrO2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10-160nM yielding a detection limit of 2.25nM (based on 3Sb/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Electrocatalytical oxidation and sensitive determination of acetaminophen on glassy carbon electrode modified with graphene–chitosan composite

    International Nuclear Information System (INIS)

    Zheng, Meixia; Gao, Feng; Wang, Qingxiang; Cai, Xili; Jiang, Shulian; Huang, Lizhang; Gao, Fei

    2013-01-01

    The electrochemical behaviors of acetaminophen (ACOP) on a graphene–chitosan (GR–CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR–CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR–CS/GCE was greatly enhanced. The values of electron transfer rate constant (k s ), diffusion coefficient (D) and the surface adsorption amount (Γ ⁎ ) of ACOP on GR–CS/GCE were determined to be 0.25 s −1 , 3.61 × 10 −5 cm 2 s −1 and 1.09 × 10 −9 mol cm −2 , respectively. Additionally, a 2e − /2H + electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0 × 10 −6 to 1.0 × 10 −4 M with a low detection limit of 3.0 × 10 −7 M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations. Highlights: ► A chitosan–graphene nanocomposite modified glassy carbon electrode was prepared. ► The modified electrode was electrochemically characterized by CV and EIS. ► Electro-oxidation of acetaminophen was examined on the modified electrode. ► Sensing analysis of the modified electrode toward acetaminophen was studied

  5. Combined determination of circulating miR-196a and miR-196b levels produces high sensitivity and specificity for early detection of oral cancer.

    Science.gov (United States)

    Lu, Ya-Ching; Chang, Joseph Tung-Chieh; Huang, Yu-Chen; Huang, Chi-Che; Chen, Wen-Ho; Lee, Li-Yu; Huang, Bing-Shen; Chen, Yin-Ju; Li, Hsiao-Fang; Cheng, Ann-Joy

    2015-02-01

    The aim of this study was to determine whether the oncogenic microRNA family members miR-196a and miR-196b can be circulating biomarkers for the early detection of oral cancer. To determine the stability of circulating miRNA, the blood sample was aliquot and stored at different temperature conditions for analysis. To assess the diagnostic efficacy, we determined the levels of miR-196s in plasma samples, including 53 from healthy individuals, 16 from pre-cancer patients, and 90 from oral cancer patients. In general, circulating miRNA was very stable when storing plasma samples at -20°C or below. In clinical study, both circulating miR-196a and miR-196b were substantially up-regulated in patients with oral pre-cancer lesions (5.9- and 14.8-fold, respectively; P oral cancer patients (9.3- and 17.0-fold, respectively; P cancer patients (AUC = 0.764 or 0.840, miR-196a or miR-196b, respectively), and between normal and cancer patients (AUC = 0.864 or 0.960, miR-196a or miR-196b, respectively). The combined determination of miR-196a and miR-196b levels produces excellent sensitivity and specificity in the diagnosis of patients with oral pre-cancer (AUC = 0.845) or oral cancer (AUC = 0.963), as well as in the prediction of potential malignancy (AUC = 0.950, sensitivity = 91%, specificity = 85%). Combined determination of circulating miR-196a and miR-196b levels may serve as panel plasma biomarkers for the early detection of oral cancer. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  6. A Sensitive and Rapid Method to Determine the Adhesion Capacity of Probiotics and Pathogenic Microorganisms to Human Gastrointestinal Mucins

    Directory of Open Access Journals (Sweden)

    Bélinda Ringot-Destrez

    2018-05-01

    Full Text Available Mucus is the habitat for the microorganisms, bacteria and yeast that form the commensal flora. Mucins, the main macromolecules of mucus, and more specifically, the glycans that cover them, play essential roles in microbial gastrointestinal colonization. Probiotics and pathogens must also colonize mucus to have lasting positive or deleterious effects. The question of which mucin-harboured glycan motifs favour the adhesion of specific microorganisms remains very poorly studied. In the current study, a simple test based on the detection of fluorescent-labeled microorganisms raised against microgram amounts of mucins spotted on nitrocellulose was developed. The adhesion of various probiotic, commensal and pathogenic microorganisms was evaluated on a panel of human purified gastrointestinal mucins and compared with that of commercially available pig gastric mucins (PGM and of mucins secreted by the colonic cancer cell line HT29-MTX. The latter two proved to be very poor indicators of adhesion capacity on intestinal mucins. Our results show that the nature of the sialylated cores of O-glycans, determined by MALDI MS-MS analysis, potentially enables sialic acid residues to modulate the adhesion of microorganisms either positively or negatively. Other identified factors affecting the adhesion propensity were O-glycan core types and the presence of blood group motifs. This test should help to select probiotics with enhanced adhesion capabilities as well as deciphering the role of specific mucin glycotopes on microbial adhesion.

  7. A Highly Sensitive Electrochemical DNA Biosensor from Acrylic-Gold Nano-composite for the Determination of Arowana Fish Gender

    Science.gov (United States)

    Rahman, Mahbubur; Heng, Lee Yook; Futra, Dedi; Chiang, Chew Poh; Rashid, Zulkafli A.; Ling, Tan Ling

    2017-08-01

    The present research describes a simple method for the identification of the gender of arowana fish ( Scleropages formosus). The DNA biosensor was able to detect specific DNA sequence at extremely low level down to atto M regimes. An electrochemical DNA biosensor based on acrylic microsphere-gold nanoparticle (AcMP-AuNP) hybrid composite was fabricated. Hydrophobic poly(n-butylacrylate-N-acryloxysuccinimide) microspheres were synthesised with a facile and well-established one-step photopolymerization procedure and physically adsorbed on the AuNPs at the surface of a carbon screen printed electrode (SPE). The DNA biosensor was constructed simply by grafting an aminated DNA probe on the succinimide functionalised AcMPs via a strong covalent attachment. DNA hybridisation response was determined by differential pulse voltammetry (DPV) technique using anthraquinone monosulphonic acid redox probe as an electroactive oligonucleotide label (Table 1). A low detection limit at 1.0 × 10-18 M with a wide linear calibration range of 1.0 × 10-18 to 1.0 × 10-8 M ( R 2 = 0.99) can be achieved by the proposed DNA biosensor under optimal conditions. Electrochemical detection of arowana DNA can be completed within 1 hour. Due to its small size and light weight, the developed DNA biosensor holds high promise for the development of functional kit for fish culture usage.

  8. A simple and sensitive vortex-assisted ionic liquid-dispersive microextraction and spectrophotometric determination of selenium in food samples.

    Science.gov (United States)

    Bağda, Esra; Tüzen, Mustafa

    2017-10-01

    In the present study, a novel and eco-friendly vortex-assisted ionic liquid-based microextraction method was developed for the determination of selenium in food. The microextraction method is based on the liberation of iodine in the presence of selenium; the liberated iodine reacts with I - to form I 3 - . Anionic I 3 - reacts with cationic crystal violet dye, and the product is extracted into 1-hexyl-3-methylimidazolium hexafluorophosphate phase in the presence of Triton X-114. The proposed method is linear in the range of 2.0-70µgL -1 and has a detection limit of 9.8×10 -2 µgL -1 . Relative standard deviations were 3.67% and 2.89% for the five replicate measurements of 14 and 35µgL -1 Se(IV), respectively. The proposed method was successfully applied to different food samples (NIST SRM 2976 mussel tissue, pepper, ginger, wheat flour, red lentil, traditional soup, cornflour, cornstarch, and garlic) after microwave digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A simple and sensitive immunoassay for the determination of human chorionic gonadotropin by graphene-based chemiluminescence resonance energy transfer.

    Science.gov (United States)

    Lei, Jiuqian; Jing, Tao; Zhou, Tingting; Zhou, Yusun; Wu, Wei; Mei, Surong; Zhou, Yikai

    2014-04-15

    In this study, we report a strategy of chemiluminescence resonance energy transfer (CRET) using graphene as an efficient long-range energy acceptor. Magnetic nanoparticles were also used in CRET for simple magnetic separation and immobilization of horseradish peroxidase (HRP)-labeled anti-HCG antibody. In the design of CRET system, the sandwich-type immunocomplex was formed between human chorionic gonadotropin (HCG, antigen) and two different antibodies bridged the magnetic nanoparticles and graphene (acceptors), which led to the occurrence of CRET from chemiluminescence light source to graphene. After optimizing the experimental conditions, the quenching of chemiluminescence signal depended linearly on the concentration of HCG in the range of 0.1 mIU mL(-1)-10 mIU mL(-1) and the detection limit was 0.06 mIU mL(-1). The proposed method was successfully applied for the determination of HCG levels in saliva and serum samples, and the results were in good agreement with the plate ELISA with colorimetric detection. It could also be developed for detection of other antigen-antibody immune complexes by using the corresponding antigens and respective antibodies. © 2013 Published by Elsevier B.V.

  10. Facile and sensitive determination of N-nitrosamines in food samples by high-performance liquid chromatography via combining fluorescent labeling with dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Lu, Shuaimin; Wu, Di; Li, Guoliang; Lv, Zhengxian; Gong, Peiwei; Xia, Lian; Sun, Zhiwei; Chen, Guang; Chen, Xuefeng; You, Jinmao; Wu, Yongning

    2017-11-01

    The intake of N-nitrosamines (NAs) from foodstuffs is considered to be an important influence factor for several cancers. But the rapid and sensitive screening of NAs remains a challenge in the field of food safety. Inspired by that, a sensitive and rapid method was demonstrated for determination of five NAs (Nitrosopyrrolidine, Nitrosodimethylamine, Nitrosodiethylamine, Nitrosodipropylamine and Nitrosodibutylamine) using dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The NAs were firstly denitrosated and labeled by 2-(11H-benzo[a]carbazol-11-yl) ethyl carbonochloridate (BCEC-Cl) and finally enriched by DLLME. Furthermore, the main DLLME conditions were optimized systematically. Under the optimal conditions, satisfactory limits of detection (LODs) were obtained with a range of 0.01-0.07ngg -1 , which were significantly lower than the reported methods. The developed method showed many merits including rapidity, simplicity, high sensitivity and excellent selectivity, which shows a broad prospect in food safety analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. A novel FbFP-based biosensor toolbox for sensitive in vivo determination of intracellular pH.

    Science.gov (United States)

    Rupprecht, Christian; Wingen, Marcus; Potzkei, Janko; Gensch, Thomas; Jaeger, Karl-Erich; Drepper, Thomas

    2017-09-20

    The intracellular pH is an important modulator of various bio(techno)logical processes such as enzymatic conversion of metabolites or transport across the cell membrane. Changes of intracellular pH due to altered proton distribution can thus cause dysfunction of cellular processes. Consequently, accurate monitoring of intracellular pH allows elucidating the pH-dependency of (patho)physiological and biotechnological processes. In this context, genetically encoded biosensors represent a powerful tool to determine intracellular pH values non-invasively and with high spatiotemporal resolution. We have constructed a toolbox of novel genetically encoded FRET-based pH biosensors (named Fluorescence Biosensors for pH or FluBpH) that utilizes the FMN-binding fluorescent protein EcFbFP as donor domain. In contrast to many fluorescent proteins of the GFP family, EcFbFP exhibits a remarkable tolerance towards acidic pH (pK a ∼3.2). To cover the broad range of physiologically relevant pH values, three EYFP variants exhibiting pK a values of 5.7, 6.1 and 7.5 were used as pH-sensing FRET acceptor domains. The resulting biosensors FluBpH 5.7, FluBpH 6.1 and FluBpH 7.5 were calibrated in vitro and in vivo to accurately evaluate their pH indicator properties. To demonstrate the in vivo applicability of FluBpH, changes of intracellular pH were ratiometrically measured in E. coli cells during acid stress. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Determination of Baylisascaris schroederi infection in wild giant pandas by an accurate and sensitive PCR/CE-SSCP method.

    Directory of Open Access Journals (Sweden)

    Wenping Zhang

    Full Text Available It has been recognized that other than habitat loss, degradation and fragmentation, the infection of the roundworm Baylisascaris schroederi (B. schroederi is one of the major causes of death in wild giant pandas. However, the prevalence and intensity of the parasite infection has been inconsistently reported through a method that uses sedimentation-floatation followed by a microscope examination. This method fails to accurately determine infection because there are many bamboo residues and/or few B. schroederi eggs in the examined fecal samples. In the present study, we adopted a method that uses PCR and capillary electrophoresis combined with a single-strand conformation polymorphism analysis (PCR/CE-SSCP to detect B. schroederi infection in wild giant pandas at a nature reserve, and compared it to the traditional microscope approach. The PCR specifically amplified a single band of 279-bp from both fecal samples and positive controls, which was confirmed by sequence analysis to correspond to the mitochondrial COII gene of B. schroederi. Moreover, it was demonstrated that the amount of genomic DNA was linearly correlated with the peak area of the CE-SSCP analysis. Thus, our adopted method can reliably detect the infectious prevalence and intensity of B. schroederi in wild giant pandas. The prevalence of B. schroederi was found to be 54% in the 91 fecal samples examined, and 48% in the fecal samples of 31 identified individual giant pandas. Infectious intensities of the 91 fecal samples were detected to range from 2.8 to 959.2 units/gram, and from 4.8 to 959.2 units/gram in the fecal samples of the 31 identified giant pandas. For comparison, by using the traditional microscope method, the prevalence of B. schroederi was found to be only 33% in the 91 fecal samples, 32% in the fecal samples of the 31 identified giant pandas, and no reliable infectious intensity was observed.

  13. Cloud point extraction-fluorimetric combined methodology for the determination of trace warfarin based on the sensitization effect of supramolecule

    Energy Technology Data Exchange (ETDEWEB)

    Chang Zheng [Department of Applied Chemistry of College of Science, Xi' an University of Technology, Xi' an 710048 (China); College of Chemistry and Materials Science, Northwest University, 229 North Taibai Road, Xi' an 710069 (China); Yan Hongtao, E-mail: cz610@163.com [College of Chemistry and Materials Science, Northwest University, 229 North Taibai Road, Xi' an 710069 (China)

    2012-03-15

    Compared to the fluorescence spectra of warfarin in pure ethanol and in the presence of the nonionic surfactant Tergitol 15-S-7 after cloud point extraction (CPE), it can be seen that the fluorescence emission peak underwent an obvious red shift and the fluorescence intensity of warfarin was significantly increased in the presence of Tergitol 15-S-7. In order to confirm Tergitol 15-S-7-induced supramolecular effects, the investigations on the fluorescence quantum yields of warfarin in the micellar medium and pure ethanol were performed. The experimental results showed that the supramolecular interactions between Tergitol 15-S-7 and the warfarin excimers played a key role for improving the warfarin fluorescence properties. Based on these facts, a simple fluorometric method combined with CPE for the determination of trace warfarin was developed for the first time. Under optimized experimental conditions, the linear concentration range for warfarin was 3.0 Multiplication-Sign 1.0{sup -9}-1.0 Multiplication-Sign 10{sup -6} mol L{sup -1} and the detection limit was 3.3 Multiplication-Sign 10{sup -10} mol L{sup -1}. And, the proposed method was approved to be appropriate for monitoring warfarin in actual pharmaceutical formulations and biological fluid samples by recovery test, in comparison with other reported methods being satisfactory. - Highlights: Black-Right-Pointing-Pointer A CPE fluorescence method for trace warfarin was developed for the first time. Black-Right-Pointing-Pointer Supramolecule effects play a key role for improving the fluorescence property. Black-Right-Pointing-Pointer Notion presents an opportunity so far neglected area of CPE investigation. Black-Right-Pointing-Pointer Without previous treatment, urine species after CPE had no significant interference.

  14. Cloud point extraction-fluorimetric combined methodology for the determination of trace warfarin based on the sensitization effect of supramolecule

    International Nuclear Information System (INIS)

    Chang Zheng; Yan Hongtao

    2012-01-01

    Compared to the fluorescence spectra of warfarin in pure ethanol and in the presence of the nonionic surfactant Tergitol 15-S-7 after cloud point extraction (CPE), it can be seen that the fluorescence emission peak underwent an obvious red shift and the fluorescence intensity of warfarin was significantly increased in the presence of Tergitol 15-S-7. In order to confirm Tergitol 15-S-7-induced supramolecular effects, the investigations on the fluorescence quantum yields of warfarin in the micellar medium and pure ethanol were performed. The experimental results showed that the supramolecular interactions between Tergitol 15-S-7 and the warfarin excimers played a key role for improving the warfarin fluorescence properties. Based on these facts, a simple fluorometric method combined with CPE for the determination of trace warfarin was developed for the first time. Under optimized experimental conditions, the linear concentration range for warfarin was 3.0×1.0 −9 –1.0×10 −6 mol L −1 and the detection limit was 3.3×10 −10 mol L −1 . And, the proposed method was approved to be appropriate for monitoring warfarin in actual pharmaceutical formulations and biological fluid samples by recovery test, in comparison with other reported methods being satisfactory. - Highlights: ► A CPE fluorescence method for trace warfarin was developed for the first time. ► Supramolecule effects play a key role for improving the fluorescence property. ► Notion presents an opportunity so far neglected area of CPE investigation. ► Without previous treatment, urine species after CPE had no significant interference.

  15. Synthesis of Fe–Cu/TiO{sub 2} nanostructure and its use in construction of a sensitive and selective sensor for metformin determination

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand@yahoo.com; Shamsipur, Mojtaba; Paimard, Giti; Feyzi, Mostafa; Jafari, Fataneh

    2014-09-01

    A carbon paste electrode modified with Fe-Cu/TiO{sub 2} was prepared and used for low level determination of metformin (MET) using square wave adsorptive stripping voltammetry (SWAdSV). The Fe-Cu/TiO{sub 2} nanoparticle was synthesized by a modified sol–gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD) and N{sub 2} physisorption. Also, electrochemical properties of the prepared nanocomposite modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 15 nM to 75 μM MET, with a detection limit of 3 nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for MET determination in real samples such as human urine and pharmaceutical formulations. - Highlights: • A carbon paste modified electrode for determination of MET was developed. • The synthesized Fe-Cu/TiO{sub 2} nanocomposite was used as a modifier. • The sensor was successfully applied for MET determination in real samples. • Square wave adsorptive stripping voltammetric method was used for MET determination.

  16. Synthesis of Fe–Cu/TiO2 nanostructure and its use in construction of a sensitive and selective sensor for metformin determination

    International Nuclear Information System (INIS)

    Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Paimard, Giti; Feyzi, Mostafa; Jafari, Fataneh

    2014-01-01

    A carbon paste electrode modified with Fe-Cu/TiO 2 was prepared and used for low level determination of metformin (MET) using square wave adsorptive stripping voltammetry (SWAdSV). The Fe-Cu/TiO 2 nanoparticle was synthesized by a modified sol–gel method. The surface structure and composition of nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction analysis (XRD) and N 2 physisorption. Also, electrochemical properties of the prepared nanocomposite modified electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range of 15 nM to 75 μM MET, with a detection limit of 3 nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for MET determination in real samples such as human urine and pharmaceutical formulations. - Highlights: • A carbon paste modified electrode for determination of MET was developed. • The synthesized Fe-Cu/TiO 2 nanocomposite was used as a modifier. • The sensor was successfully applied for MET determination in real samples. • Square wave adsorptive stripping voltammetric method was used for MET determination

  17. Radioecological sensitivity

    International Nuclear Information System (INIS)

    Howard, Brenda J.; Strand, Per; Assimakopoulos, Panayotis

    2003-01-01

    After the release of radionuclide into the environment it is important to be able to readily identify major routes of radiation exposure, the most highly exposed individuals or populations and the geographical areas of most concern. Radioecological sensitivity can be broadly defined as the extent to which an ecosystem contributes to an enhanced radiation exposure to Man and biota. Radioecological sensitivity analysis integrates current knowledge on pathways, spatially attributes the underlying processes determining transfer and thereby identifies the most radioecologically sensitive areas leading to high radiation exposure. This identifies where high exposure may occur and why. A framework for the estimation of radioecological sensitivity with respect to humans is proposed and the various indicators by which it can be considered have been identified. These are (1) aggregated transfer coefficients (Tag), (2) action (and critical) loads, (3) fluxes and (4) individual exposure of humans. The importance of spatial and temporal consideration of all these outputs is emphasized. Information on the extent of radionuclide transfer and exposure to humans at different spatial scales is needed to reflect the spatial differences which can occur. Single values for large areas, such as countries, can often mask large variation within the country. Similarly, the relative importance of different pathways can change with time and therefore assessments of radiological sensitivity are needed over different time periods after contamination. Radioecological sensitivity analysis can be used in radiation protection, nuclear safety and emergency preparedness when there is a need to identify areas that have the potential of being of particular concern from a risk perspective. Prior identification of radioecologically sensitive areas and exposed individuals improve the focus of emergency preparedness and planning, and contribute to environmental impact assessment for future facilities. The

  18. Analysis of the sensitivity of the impact resonance frequency test as a tool to determine the elastic properties of bituminous materials

    International Nuclear Information System (INIS)

    Tauste, R.; Moreno-Navarro, F.; Gallego, R.; Rubio-Gámez, M.C.

    2017-01-01

    The modulus value of bituminous materials is a key factor in the design of road pavements and the estimation of their life service. This parameter can be measured in laboratory but, unfortunately, this requires the deterioration of the pavement so as the consumption of time and resources. Therefore, this study analyses the feasibility of using impact resonance frequency tests as an alternative to traditional methods for determining the dynamic modulus of bituminous mixtures. The sensitivity of this technique has been studied by analyzing its repeatability and reproducibility, studying the variations in the values measured by modifying the dimensions of the specimens, test temperatures and types of mixture tested. In addition, this non-destructive technique has been compared with other traditional tests used to determine the elastic properties of bituminous materials. The results show that this test could be an interesting tool to characterize the properties and damage state of asphalt layers. [es

  19. Analysis of the sensitivity of the impact resonance frequency test as a tool to determine the elastic properties of bituminous materials

    Directory of Open Access Journals (Sweden)

    R. Tauste

    2017-07-01

    Full Text Available The modulus value of bituminous materials is a key factor in the design of road pavements and the estimation of their life service. This parameter can be measured in laboratory but, unfortunately, this requires the deterioration of the pavement so as the consumption of time and resources. Therefore, this study analyses the feasibility of using impact resonance frequency tests as an alternative to traditional methods for determining the dynamic modulus of bituminous mixtures. The sensitivity of this technique has been studied by analyzing its repeatability and reproducibility, studying the variations in the values measured by modifying the dimensions of the specimens, test temperatures and types of mixture tested. In addition, this non-destructive technique has been compared with other traditional tests used to determine the elastic properties of bituminous materials. The results show that this test could be an interesting tool to characterize the properties and damage state of asphalt layers.

  20. Pretreatment IgE sensitization patterns determine the molecular profile of the IgG4 response during updosing of subcutaneous immunotherapy with timothy grass pollen extract

    DEFF Research Database (Denmark)

    Schmid, Johannes Martin; Würtzen, Peter Adler; Dahl, Ronald

    2016-01-01

    BACKGROUND: Allergen immunotherapy is an effective treatment of allergic rhinoconjunctivitis. Clinical efficacy is associated with improvement of basophil sensitivity and an increase in allergen-specific immunoglobulin concentration. OBJECTIVE: We sought to determine whether changes in allergen...... component-specific serum IgE and IgG4 levels during the updosing phase of subcutaneous immunotherapy (SCIT) are biomarkers of the immunologic changes that can lead to treatment efficacy. METHODS: Twenty-four subjects with grass pollen-induced allergic rhinoconjunctivitis were randomized 3:1 to receive SCIT...... (Alutard SQ) or to an open control group. IgE and IgG4 concentrations were determined for the major allergens Phl p 1 or Phl p 5 by using ImmunoCAP and for 8 grass pollen molecules by using Immuno Solid-phase Allergy Chip (ISAC) before treatment and after updosing. RESULTS: Levels of specific IgE against...

  1. Determination of the depth-resolved Stokes parameters of light backscattered from turbid media by use of polarization-sensitive optical coherence tomography

    International Nuclear Information System (INIS)

    Boer, J.F. de; Milner, T.E.; Nelson, J.S.

    1999-01-01

    Polarization-sensitive optical coherence tomography (PS-OCT) was used to characterize completely the polarization state of light backscattered from turbid media. Using a low-coherence light source, one can determine the Stokes parameters of backscattered light as a function of optical path in turbid media. To demonstrate the application of this technique we determined the birefringence and the optical axis in fibrous tissue (rodent muscle) and in vivo rodent skin. PS-OCT has potentially useful applications in biomedical optics by imaging simultaneously the structural properties of turbid biological materials and their effects on the polarization state of backscattered light. This method may also find applications in material science for investigation of polarization properties (e.g., birefringence) in opaque media such as ceramics and crystals. copyright 1999 Optical Society of America

  2. Development of an Ultrasonication-Assisted Extraction Based HPLC With a Fluorescence Method for Sensitive Determination of Aflatoxins in Highly Acidic Hibiscus sabdariffa

    Directory of Open Access Journals (Sweden)

    Xiaofei Liu

    2018-04-01

    Full Text Available The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD after ultrasonication-assisted extraction, immunoaffinity column (IAC clean-up and on-line post-column photochemical derivatization (PCD. Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0 to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999, sensitivity (limits of detection (LODs and limits of quantitation (LOQs of 0.15–0.65 and 0.53–2.18 μg/kg, respectively, precision (RSD <11%, stability (RSD of 0.2–3.6%, and accuracy (recovery rates of 86.0–102.3%, which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1 at 3.11 μg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

  3. Determining

    Directory of Open Access Journals (Sweden)

    Bahram Andarzian

    2015-06-01

    Full Text Available Wheat production in the south of Khuzestan, Iran is constrained by heat stress for late sowing dates. For optimization of yield, sowing at the appropriate time to fit the cultivar maturity length and growing season is critical. Crop models could be used to determine optimum sowing window for a locality. The objectives of this study were to evaluate the Cropping System Model (CSM-CERES-Wheat for its ability to simulate growth, development, grain yield of wheat in the tropical regions of Iran, and to study the impact of different sowing dates on wheat performance. The genetic coefficients of cultivar Chamran were calibrated for the CSM-CERES-Wheat model and crop model performance was evaluated with experimental data. Wheat cultivar Chamran was sown on different dates, ranging from 5 November to 9 January during 5 years of field experiments that were conducted in the Khuzestan province, Iran, under full and deficit irrigation conditions. The model was run for 8 sowing dates starting on 25 October and repeated every 10 days until 5 January using long-term historical weather data from the Ahvaz, Behbehan, Dezful and Izeh locations. The seasonal analysis program of DSSAT was used to determine the optimum sowing window for different locations as well. Evaluation with the experimental data showed that performance of the model was reasonable as indicated by fairly accurate simulation of crop phenology, biomass accumulation and grain yield against measured data. The normalized RMSE were 3%, 2%, 11.8%, and 3.4% for anthesis date, maturity date, grain yield and biomass, respectively. Optimum sowing window was different among locations. It was opened and closed on 5 November and 5 December for Ahvaz; 5 November and 15 December for Behbehan and Dezful;and 1 November and 15 December for Izeh, respectively. CERES-Wheat model could be used as a tool to evaluate the effect of sowing date on wheat performance in Khuzestan conditions. Further model evaluations

  4. A role for protein kinase C in the regulation of membrane fluidity and Ca²(+) flux at the endoplasmic reticulum and plasma membranes of HEK293 and Jurkat cells.

    Science.gov (United States)

    Chen, Lihong; Meng, Qingli; Jing, Xian; Xu, Pingxiang; Luo, Dali

    2011-02-01

    Protein kinase C (PKC) plays a prominent role in the regulation of a variety of cellular functions, including Ca²(+) signalling. In HEK293 and Jurkat cells, the Ca²(+) release and Ca²(+) uptake stimulated by several different activators were attenuated by activation of PKC with phorbol myristate acetate (PMA) or 1-oleoyl-2-acetyl-sn-glycerol (OAG) and potentiated by PKC inhibition with Gö6983 or knockdown of PKCα or PKCβ using shRNA. Immunostaining and Western blotting analyses revealed that PKCα and PKCβII accumulated at the plasma membrane (PM) and that these isoforms, along with PKCβI, also translocated to the endoplasmic reticulum (ER) upon activation with PMA. Measurements of membrane fluidity showed that, like the cell membrane stabilizers bovine serum albumin (BSA) and ursodeoxycholate (UDCA), PMA and OAG significantly reduced the fluidity of both the PM and ER membranes; these effects were blocked in PKC-knockdown cells. Interestingly, both BSA and UDCA inhibited the Ca²(+) responses to agonists to the same extent as PMA, whereas Tween 20, which increases membrane fluidity, raised the internal Ca²(+) concentration. Thus, activation of PKC induces both translocation of PKC to the PM and ER membranes and downregulation of membrane fluidity, thereby negatively modulating Ca²(+) flux. Copyright © 2010 Elsevier Inc. All rights reserved.

  5. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium

    International Nuclear Information System (INIS)

    Afkhami, Abbas; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-01-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03–200 μmol L −1 . The lower detection limits were found to be 0.02 μmol L −1 . The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility. - Highlights: • GCE was modified with multiwalled carbon nanotube and gold nanoparticles. • AuNP/MWCNT/GCE was used for the determination of diclofenac sodium. • Modified electrode was characterized by SEM, EDS and EIS. • The proposed method showed excellent analytical figures of merit. • This sensor was used for the determination of diclofenac sodium in real samples.

  6. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium

    Energy Technology Data Exchange (ETDEWEB)

    Afkhami, Abbas, E-mail: afkhami@basu.ac.ir; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-02-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03–200 μmol L{sup −1}. The lower detection limits were found to be 0.02 μmol L{sup −1}. The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility. - Highlights: • GCE was modified with multiwalled carbon nanotube and gold nanoparticles. • AuNP/MWCNT/GCE was used for the determination of diclofenac sodium. • Modified electrode was characterized by SEM, EDS and EIS. • The proposed method showed excellent analytical figures of merit. • This sensor was used for the determination of diclofenac sodium in real samples.

  7. Influence of gating design on microstructure and fluidity of thin sections AA320.0 cast hypo-eutectic Al-Si alloy

    Science.gov (United States)

    Ramadan, Mohamed

    2018-05-01

    Influence of gating design especially number of ingrates on microstructure and fluidity of thin sections of 2, 4, 6 mm AA320.0 cast hypo-eutectic Al-Si alloy was evaluated for sand casting molding technique. Increasing the number of ingates improves the microstructe to be fine and more globular. About 87 μm of α-Al grain size, 0.6 α-Al grain sphericity and 37 μm dendrite arm spacing DAS are achieved by using 4 ingates in gating system. Increasing the number of ingates up to 3 increases hardness, filling area and related fluditiy of all cast samples. The minimum thickness of 2.5 mm for each ingate should be considered in order to successfully production of high quality light weight thin sections castings in sand mold.

  8. Sensitive Determination of Onco-metabolites of D- and L-2-hydroxyglutarate Enantiomers by Chiral Derivatization Combined with Liquid Chromatography/Mass Spectrometry Analysis

    Science.gov (United States)

    Cheng, Qing-Yun; Xiong, Jun; Huang, Wei; Ma, Qin; Ci, Weimin; Feng, Yu-Qi; Yuan, Bi-Feng

    2015-01-01

    2-hydroxyglutarate (2HG) is a potent competitor of α-ketoglutarate (α-KG) and can inhibit multiple α-KG dependent dioxygenases that function on the epigenetic modifications. The accumulation of 2HG contributes to elevated risk of malignant tumors. 2HG carries an asymmetric carbon atom in its carbon backbone and differentiation between D-2-hydroxyglutarate (D-2HG) and L-2-hydroxyglutarate (L-2HG) is crucially important for accurate diagnosis of 2HG related diseases. Here we developed a strategy by chiral derivatization combined with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis for highly sensitive determination of D-2HG and L-2HG enantiomers. N-(p-toluenesulfonyl)-L-phenylalanyl chloride (TSPC) was used to derivatize 2HG. The formed diastereomers by TSPC labeling can efficiently improve the chromatographic separation of D-2HG and L-2HG. And derivatization by TSPC could also markedly increase the detection sensitivities by 291 and 346 folds for D-2HG and L-2HG, respectively. Using the developed method, we measured the contents of D-2HG and L-2HG in clear cell renal cell carcinoma (ccRCC) tissues. We observed 12.9 and 29.8 folds increase of D-2HG and L-2HG, respectively, in human ccRCC tissues compared to adjacent normal tissues. The developed chiral derivatization combined with LC-ESI-MS/MS analysis offers sensitive determination of D-2HG and L-2HG enantiomers, which benefits the precise diagnosis of 2HG related metabolic diseases. PMID:26458332

  9. A hybrid molecularly imprinted polymer coated quantum dot nanocomposite optosensor for highly sensitive and selective determination of salbutamol in animal feeds and meat samples.

    Science.gov (United States)

    Raksawong, Phannika; Chullasat, Kochaporn; Nurerk, Piyaluk; Kanatharana, Proespichaya; Davis, Frank; Bunkoed, Opas

    2017-08-01

    A hybrid molecularly imprinted polymer (MIP)-coated quantum dot (QD) nanocomposite was synthesized and applied as a fluorescence probe for the highly sensitive and selective determination of salbutamol. The hybrid MIP-coated QD nanocomposite was synthesized via a copolymerization process in the presence of thioglycolic acid capped CdTe QDs with salbutamol as a template, 3-aminopropyltriethoxysilane as the functional monomer, and tetraethyl orthosilicate as a cross-linker. The optimum molar ratio of template, monomer, and cross-linker was 1:6:20. The fluorescence intensity of the hybrid MIP-coated QDs was efficiently quenched after salbutamol rebound to the recognition sites, as a result of charge transfer from QDs to salbutamol. The synthesized hybrid MIP-coated QD nanocomposite showed high sensitivity and good selectivity toward salbutamol. Under the optimal recognition conditions, the fluorescence intensity was quenched linearly with increasing concentration of salbutamol in the range from 0.10 to 25.0 μg L -1 , with a detection limit of 0.034 μg L -1 . The hybrid optosensor developed was successfully applied in the determination of salbutamol in animal feeds and meat samples. Satisfactory recoveries were obtained in the range from 85% to 98%, with a standard deviation of less than 8%. Furthermore, the accuracy of the hybrid MIP-coated QD nanocomposite was investigated by comparison with a conventional high-performance liquid chromatography method, with the results obtained with two methods agreeing well with each other. The advantages of this sensing method are simplicity, rapidity, cost-effectiveness, high sensitivity, and good selectivity. Graphical Abstract The synthesis of hybrid MIP-coated QDs nanocomposite.

  10. Sensitive determination of enoxacin in pharmaceutical formulations by its quench effect on the fluorescence of glutathione-capped CdTe quantum dots.

    Science.gov (United States)

    Yang, Qiong; Tan, Xuanping; Yang, Jidong

    2016-02-01

    A sensitive and simple method for the determination of enoxacin (ENX) was developed based on the fluorescence quenching effect of ENX for glutathione (GSH)-capped CdTe quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 4.333 × 10(-9)  mol⋅L(-1) to 1.4 × 10(-5)  mol⋅L(-1) with a correlation coefficient (R) of 0.9987, and the detection limit (3σ/K) was 1.313 × 10(-9)  mol⋅L(-1). The corresponding mechanism has been proposed on the basis of electron transfer supported by ultraviolet-visible (UV) light absorption, fluorescence spectroscopy, and the measurement of fluorescence lifetime. The method has been applied to the determination of ENX in pharmaceutical formulations (enoxacin gluconate injections and commercial tablets) with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation. Copyright © 2015 John Wiley & Sons, Ltd.

  11. A simple and sensitive methodology for voltammetric determination of valproic acid in human blood plasma samples using 3-aminopropyletriethoxy silane coated magnetic nanoparticles modified pencil graphite electrode.

    Science.gov (United States)

    Zabardasti, Abedin; Afrouzi, Hossein; Talemi, Rasoul Pourtaghavi

    2017-07-01

    In this work, we have prepared a nano-material modified pencil graphite electrode for the sensing of valproic acid (VA) by immobilization 3-aminopropyletriethoxy silane coated magnetic nanoparticles (APTES-MNPs) on the pencil graphite surface (PGE). Electrochemical studies indicated that the APTES-MNPs efficiently increased the electron transfer kinetics between VA and the electrode and the free NH 2 groups of the APTES on the outer surface of magnetic nanoparticles can interact with carboxyl groups of VA. Based on this, we have proposed a sensitive, rapid and convenient electrochemical method for VA determination. Under the optimized conditions, the reduction peak current of VA is found to be proportional to its concentration in the range of 1.0 (±0.2) to 100.0 (±0.3) ppm with a detection limit of 0.4 (±0.1) ppm. The whole sensor fabrication process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods with using [Fe(CN) 6 ] 3-/4- as an electrochemical redox indicator. The prepared modified electrode showed several advantages such as high sensitivity, selectivity, ease of preparation and good repeatability, reproducibility and stability. The proposed method was applied to determination of valproic acid in blood plasma samples and the obtained results were satisfactory accurate. Copyright © 2017. Published by Elsevier B.V.

  12. A Study on the Frequency of Fungal Rhinosinusitis and to Determine the Sensitivity of the Isolates to Antifungal Drugs in Shiraz, Iran 2012-2013

    Directory of Open Access Journals (Sweden)

    Parisa Badiei

    2015-06-01

    Full Text Available Abstract Background: Fungal spores are present in large amounts in the nature which may cause diseases in the susceptible individuals. Fungal rhinosinusitis has been increased during recent decades. This study aims to investigate fungal rhinosinusitis in the patients with chronic needing endoscopic sinus surgery aims and to determine the sensitivity of the isolates to rhin sinusitis antifungal agents. Materials and Methods: In cross sectional study, specimens were obtained in sterile plates containing normal saline. from the suspected cases of chronic rhinosinusitis who had undergone endoscopic sinus surgery. Microscopic experiments and Cultures were done in Sabouraud Dextrose Agar medium. Minimum inhibitory concentration (MIC of the growth of fungi for seven antifungal agents against the isolates was determined using E-Test. Results: In total, specimens from 102 immunocompetent patients were examined. Nine positive specimens were presented, consisting of 3 for Aspergillus fumigatus, 3 for Penicillium, 2 for Aspergillus flavus and 1 for Alternaria. The mean age of the patients was 38 years, with 59 males and 43 females. The isolates were most sensitive to the voriconazole and amphotericin B. Conclusion: Since the prevalence of fungal rhinosinusitis is low, unfortunately, the clinicians are not attentive enough to the condition, and they initiate antifungal therapy if the patients are not responsive to antibiotics. Early diagnosis and suitable treatment can help more efficient management of patients.

  13. Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine

    International Nuclear Information System (INIS)

    Shahrokhian, Saeed; Ghalkhani, Masoumeh

    2010-01-01

    A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental variables, such as the deposited amount of modifier suspension, the pH of the supporting electrolyte, the accumulation potential and time were investigated. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2-100 μM with a detection limit of 65 nM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode can be successfully applied to the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations.

  14. Sensitive determination of melamine in milk and powdered infant formula samples by high-performance liquid chromatography using dabsyl chloride derivatization followed by dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Faraji, M; Adeli, M

    2017-04-15

    A new and sensitive pre-column derivatization with dabsyl chloride followed by dispersive liquid-liquid microextraction was developed for the analysis of melamine (MEL) in raw milk and powdered infant formula samples by high performance liquid chromatography (HPLC) with visible detection. Derivatization with dabsyl chloride leads to improving sensitivity and hydrophobicity of MEL. Under optimum conditions of derivatization and microextraction steps, the method yielded a linear calibration curve ranging from 1.0 to 500μgL -1 with a determination coefficient (R 2 ) of 0.9995. Limit of detection and limit of quantification were 0.1 and 0.3μgL -1 , respectively. The relative standard deviation (RSD%) for intra-day (repeatability) and inter-day (reproducibility) at 25 and 100μgL -1 levels of MEL was less than 7.0% (n=6). Finally, the proposed method was successfully applied for the preconcentration and determination of MEL in different raw milk and powdered infant formula, and satisfactory results were obtained (relative recovery ⩾94%). Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode as a sensitive voltammetric sensor for the determination of diclofenac sodium.

    Science.gov (United States)

    Afkhami, Abbas; Bahiraei, Atousa; Madrakian, Tayyebeh

    2016-02-01

    A simple and highly sensitive sensor for the determination of diclofenac sodium based on gold nanoparticle/multi-walled carbon nanotube modified glassy carbon electrode is reported. Scanning electron microscopy along with energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry was used to characterize the nanostructure and performance of the sensor and the results were compared with those obtained at the multi-walled carbon nanotube modified glassy carbon electrode and bare glassy carbon electrode. Under the optimized experimental conditions diclofenac sodium gave linear response over the range of 0.03-200μmolL(-1). The lower detection limits were found to be 0.02μmolL(-1). The effect of common interferences on the current response of DS was investigated. The practical application of the modified electrode was demonstrated by measuring the concentration of diclofenac sodium in urine and pharmaceutical samples. This revealed that the gold nanoparticle/multiwalled carbon nanotube modified glassy carbon electrode shows excellent analytical performance for the determination of diclofenac sodium in terms of a very low detection limit, high sensitivity, very good accuracy, repeatability and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Selective and sensitized spectrophotometric determination of trace amounts of Ni(II) ion using α-benzyl dioxime in surfactant media

    Science.gov (United States)

    Ghaedi, Mehrorang

    2007-02-01

    Highly sensitive and interference-free sensitized spectrophotometric method for the determination of Ni(II) ions is described. The method is based on the reaction between Ni(II) ion and benzyl dioxime in micellar media in the presence of sodium dodecyl sulfate (SDS). The absorbance is linear from 0.1 up to 25.0 μg mL -1 in aqueous solution with repeatability (RSD) of 1.0% at a concentration of 1 μg mL -1 and a detection limit of 0.12 ng mL -1 and molar absorption coefficient of 68,600 L mol -1 cm -1. The influence of reaction variables including type and amount of surfactant, pH, and amount of ligand and complexation time and the effect of interfering ions are investigated. The proposed procedure was applied to the determination of trace amounts of Ni(II) ion in tap water, river water, chocolate and vegetable without separation or organic solvent extraction.

  17. A simple, sensitive and rapid isocratic reversed-phase high-performance liquid chromatography method for determination and stability study of curcumin in pharmaceutical samples

    Science.gov (United States)

    Amanolahi, Farjad; Mohammadi, Ali; Kazemi Oskuee, Reza; Nassirli, Hooriyeh; Malaekeh-Nikouei, Bizhan

    2017-01-01

    Objective: This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples. Materials and Methods: The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate. Results: The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) < 0.638%. Conclusion: The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition. PMID:29062806

  18. Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokhian, Saeed, E-mail: shahrokhian@sharif.ed [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Ghalkhani, Masoumeh [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of)

    2010-04-15

    A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental variables, such as the deposited amount of modifier suspension, the pH of the supporting electrolyte, the accumulation potential and time were investigated. Under optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2-100 muM with a detection limit of 65 nM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode can be successfully applied to the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations.

  19. pH Optimum of Hemagglutinin-Mediated Membrane Fusion Determines Sensitivity of Influenza A Viruses to the Interferon-Induced Antiviral State and IFITMs.

    Science.gov (United States)

    Gerlach, Thomas; Hensen, Luca; Matrosovich, Tatyana; Bergmann, Janina; Winkler, Michael; Peteranderl, Christin; Klenk, Hans-Dieter; Weber, Friedemann; Herold, Susanne; Pöhlmann, Stefan; Matrosovich, Mikhail

    2017-06-01

    The replication and pathogenicity of influenza A viruses (IAVs) critically depend on their ability to tolerate the antiviral interferon (IFN) response. To determine a potential role for the IAV hemagglutinin (HA) in viral sensitivity to IFN, we studied the restriction of IAV infection in IFN-β-treated human epithelial cells by using 2:6 recombinant IAVs that shared six gene segments of A/Puerto Rico/8/1934 virus (PR8) and contained HAs and neuraminidases of representative avian, human, and zoonotic H5N1 and H7N9 viruses. In A549 and Calu-3 cells, viruses displaying a higher pH optimum of HA-mediated membrane fusion, H5N1-PR8 and H7N9-PR8, were less sensitive to the IFN-induced antiviral state than their counterparts with HAs from duck and human viruses, which fused at a lower pH. The association between a high pH optimum of fusion and reduced IFN sensitivity was confirmed by using HA point mutants of A/Hong Kong/1/1968-PR8 that differed solely by their fusion properties. Furthermore, similar effects of the viral fusion pH on IFN sensitivity were observed in experiments with (i) primary human type II alveolar epithelial cells and differentiated cultures of human airway epithelial cells, (ii) nonrecombinant zoonotic and pandemic IAVs, and (iii) preparations of IFN-α and IFN-λ1. A higher pH of membrane fusion and reduced sensitivity to IFN correlated with lower restriction of the viruses in MDCK cells stably expressing the IFN-inducible transmembrane proteins IFITM2 and IFITM3, which are known to inhibit viral fusion. Our results reveal that the pH optimum of HA-driven membrane fusion of IAVs is a determinant of their sensitivity to IFN and IFITM proteins. IMPORTANCE The IFN system constitutes an important innate defense against viral infection. Substantial information is available on how IAVs avoid detection by sensors of the IFN system and disable IFN signaling pathways. Much less is known about the ability of IAVs to tolerate the antiviral activity of IFN

  20. Very sensitive electrochemical determination of diuron on glassy carbon electrode modified with reduced graphene oxide-gold nanoparticle-Nafion composite film.

    Science.gov (United States)

    Zarei, K; Khodadadi, A

    2017-10-01

    In this work, a very sensitive electrochemical sensor based on glassy carbon electrode (GCE) modified with reduced graphene oxide-gold nanoparticles/Nafion (rGO-AuNPs/Nafion) composite film was applied to determine diuron. Synthesized GO was characterized using X-ray diffraction (XRD) and UV-visible spectroscopy. The surface morphology of the rGO-AuNPs/Nafion film was also characterized using scanning electron microscopy and electrochemical impedance spectroscopy. Cyclic voltammetry (CV) and adsorptive differential pulse voltammetry (AdDPV) were applied to investigate the electrochemical response of the diuron on the modified electrode. The electrode showed a linear response at 1.0×10 -9 -1.0×10 -7 M and a detection limit of 0.3nM under the optimized conditions. The effect of some other species on the determination of diuron was investigated and the sensor showed good selectivity for determination of diuron. The constructed sensor was applied to determine diuron in enriched samples of orange juice, mineral and tap water which statistical t-test showed accuracy of method. Also the sensor was applied to obtain diuron content in the tea sample. The reliability of the proposed sensor was confirmed after comparing the results with those obtained using high performance liquid chromatography (HPLC) as a comparative method. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. A sensitive inhibition chemiluminescence method for the determination of 6-mercaptopurine in tablet and biological fluid using the reaction of luminol-Ag(III) complex in alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hanwen, E-mail: hanwen@hbu.edu.cn [College of Chemistry and Environmental Science, Hebei University, Key Laboratory of Analytical Science and Technology of Hebei Province, Baoding 071002 (China); Wang, Ting; Liu, Xuyang; Chen, Peiyun [College of Chemistry and Environmental Science, Hebei University, Key Laboratory of Analytical Science and Technology of Hebei Province, Baoding 071002 (China)

    2013-02-15

    A sensitive inhibition chemiluminescence (CL) method for the determination of 6-mercaptopurine (6-MP) is developed. The mechanism of the CL reaction between Ag(III) complex {l_brace}[Ag(HIO{sub 6}){sub 2}]{sup 5-}{r_brace} and luminol in alkaline solution was proposed, along with the inhibition mechanism of 6-MP on the CL emission. The inhibition degree of CL emission was proportional to the logarithm of 6-MP concentration. The effects of the reaction conditions on CL emission and inhibition were examined. Under the optimized conditions, the detection limit (s/n=3) was 3.7 Multiplication-Sign 10{sup -10} g ml{sup -1}. The recoveries of 6-MP were in the range of 97.7-105% with the RSD of 2.1-3.4% (n=5) for tablet samples, 103-106% with the RSDs of 1.1-2.1% for spiked serum sample, and 97.2-101% with the RSD of 2.0-4.5% for spiked urine sample. The accuracy of this method for the tablet analysis was examined by comparing with the pharmacopoeia method. The proposed method was used for the determination of 6-MP at clinically relevant concentrations in real urine and serum samples with satisfactory results. - Highlights: Black-Right-Pointing-Pointer A sensitive inhibition chemiluminescence (CL) method for the determination of 6-MP is developed. Black-Right-Pointing-Pointer The inhibition mechanism of 6-MP on the CL emission was proposed. Black-Right-Pointing-Pointer The detection limit was 3.7 Multiplication-Sign 10{sup -10} g ml{sup -1}. Black-Right-Pointing-Pointer The accuracy was examined by comparing with the pharmacopoeia method.

  2. A sensitive, rapid, and simple DR-EcoScreen bioassay for the determination of PCDD/Fs and dioxin-like PCBs in environmental and food samples.

    Science.gov (United States)

    Kojima, Hiroyuki; Takeuchi, Shinji; Iida, Mitsuru; Nakayama, Shoji F; Shiozaki, Takuya

    2018-03-01

    In developing countries in Asia, such as China, Vietnam, and Thailand, there is a strong need for the development of relatively rapid and low-cost bioassays for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in environmental and food samples. These compounds are known to induce a variety of toxic and biological effects through their ligand-specific binding of the aryl hydrocarbon receptor (AhR). Indeed, several AhR-mediated reporter gene assays are widely used as prescreening tools for high-resolution gas chromatography/high-resolution mass spectrometry (HRGC-HRMS) analysis, which individually measures 17 PCDD/Fs and 12 DL-PCBs. In 2008, we have developed a new sensitive and rapid reporter gene assay using a genetically engineered stable cell line, designated DR-EcoScreen cells. The DR-EcoScreen assay using these cells has a number of great advantages of its sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin and its simple procedure, which shows little variance in the data (within CV 10 %) compared to other reporter gene assays. In this review, we summarize the application of the DR-EcoScreen assay to the determination of PCDD/Fs and DL-PCBs in ambient air samples, in fish and shellfish samples, and in flue gas samples from incinerators and provide potential usefulness of this bioassay for the determination of PCDD/Fs and DL-PCBs in various matrices.

  3. A sensitive multi-residue method for the determination of 35 micropollutants including pharmaceuticals, iodinated contrast media and pesticides in water.

    Science.gov (United States)

    Valls-Cantenys, Carme; Scheurer, Marco; Iglesias, Mònica; Sacher, Frank; Brauch, Heinz-Jürgen; Salvadó, Victoria

    2016-09-01

    A sensitive, multi-residue method using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to determine a representative group of 35 analytes, including corrosion inhibitors, pesticides and pharmaceuticals such as analgesic and anti-inflammatory drugs, five iodinated contrast media, β-blockers and some of their metabolites and transformation products in water samples. Few other methods are capable of determining such a broad range of contrast media together with other analytes. We studied the parameters affecting the extraction of the target analytes, including sorbent selection and extraction conditions, their chromatographic separation (mobile phase composition and column) and detection conditions using two ionisation sources: electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI). In ord